Re: [Aus-soaring] slip in thermals?

[glenn_mc]

Strawberry fields forever  .


Sent from my SAMSUNG Galaxy Note5 on the Telstra Mobile Network
 Original message From: Richard Frawley  
Date: 17/1/19  5:24 pm  (GMT+10:00) To: "Discussion of issues relating to 
Soaring in Australia."  Subject: Re: 
[Aus-soaring] slip in thermals? 
Nothing to get strung out about then
On 17 Jan 2019, at 5:10 pm, Ben Coleman  wrote:

I fly with the string out a little.  The glider seems to feel more 
balanced/coordinated with less aileron input rewuired to maintain a constant 
circle. 
I have flaperons though so maybe drag from aileron deflection doesn't apply to 
me, must admit to not analysing it much.
Cheers Ben 
On Thu, 17 Jan. 2019, 7:16 am Mike Borgelt http://lists.base64.com.au/listinfo/aus-soaring


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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

Nothing to get strung out about then

> On 17 Jan 2019, at 5:10 pm, Ben Coleman  wrote:
> 
> I fly with the string out a little.  The glider seems to feel more 
> balanced/coordinated with less aileron input rewuired to maintain a constant 
> circle. 
> 
> I have flaperons though so maybe drag from aileron deflection doesn't apply 
> to me, must admit to not analysing it much.
> 
> Cheers Ben 
> 
>> On Thu, 17 Jan. 2019, 7:16 am Mike Borgelt > wrote:
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Your technique may not be doing what you think it is.
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> 
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Re: [Aus-soaring] slip in thermals?

[Ben Coleman]

I fly with the string out a little.  The glider seems to feel more
balanced/coordinated with less aileron input rewuired to maintain a
constant circle.

I have flaperons though so maybe drag from aileron deflection doesn't apply
to me, must admit to not analysing it much.

Cheers Ben

On Thu, 17 Jan. 2019, 7:16 am Mike Borgelt  When circling in a thermal, do you
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
>
>
> Your technique may not be doing what you think it is.
>
> Mike
>
>
>
>
>
>
> *Borgelt Instruments* -
> *design & manufacture of quality soaring instrumentation since 1978 *
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Thanks, Glenn.



Mike

At 02:06 PM 1/17/2019, you wrote:

Hi Mike
I  usually fly with a bit of top rudder in 
thetmals i.e. string pointing towards uppermost 
wing. It prevents being blown out of the lift in 
gusty thermals and is useful when down low scratching away.

Cheers
Glenn



Sent from my SAMSUNG Galaxy Note5 on the Telstra Mobile Network

 Original message 
From: Mike Borgelt 
Date: 17/1/19 10:42 am (GMT+10:00)
To: "Discussion of issues relating to Soaring in 
Australia." 

Subject: Re: [Aus-soaring] slip in thermals?

5 replies and nobody wants to say what they personally try to do or why.

Never mind.


Mike






At 09:39 AM 1/17/2019, you wrote:

Good morning all
You might want to refer to "Advanced Soaring Made Easy" pages 194 and 195.
Cheers
Bernard



Sent from my Samsung Galaxy smartphone.

 Original message 
From: Bob Dircks 
Date: 17/01/2019 10:03 (GMT+09:30)
To: "Discussion of issues relating to Soaring 
in Australia." 

Subject: Re: [Aus-soaring] slip in thermals?

Good points Richard,

However I still find the use of the word "pointing" very ambiguous.

I suggest that "pointing" indicates a direction 
radiating from the viewpoint.
This would have us discussing the forward 
direction of the string,  while it is more 
common to consider the rearward direction of 
the string. ie it's trailing direction.




On Thu, 17 Jan. 2019, 10:18 am Richard Frawley 
<<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com wrote:
the string can be either pointing in to the 
thermal centre or pointing out away from the core
there is some conjecture that with some 
aircraft (I read that it was mainly older 
pre-1980 craft) that with the string pointing 
to the outside, they may be more efficient in the climb.
There are also some views that say that 
polyhedral vs straight wings tend to set up a 
balance that has the string pointing out.
I have not yet seen any empiric data or 
detailed theory that speaks to these 
suppositions, I expect it exists somewhere tho.

More questions and less answers still…..
<






Richard Frawley
<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com
We do not inherit the earth from our ancestors, 
we borrow it from our children








On 17 Jan 2019, at 10:12 am, Bob Dircks 
<<mailto:dircks@gmail.com>dircks@gmail.com> wrote:

Mike,
In your original question,
Part b,
By "pointing" I presume you mean "trailing" ?
To me, in this case "pointing" could be the 
direction of the forward end of the string.


On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com> 
mborg...@borgeltinstruments.com wrote:

So how about answering the questions?

Mike
At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.
This might b able to be worked out 
mathematically given the airflows angle on 
the wing and fuselage drags differences
I suspect that are several aerodynamic 
factors would have to be considered, 
especially given the the thermal core is dynamic.


A question for modern designers perhaps, 
especially when all aviation design is a trade off










Richard Frawley
<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com
We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com> 
mborg...@borgeltinstruments.com> wrote:

At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how 
to you tell if one technique is better than another. What is a useful baseline?




Climbing better than the other gliders is 
the test but what if everybody is using the same less than optimum technique?

Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com> 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?

Your technique may not be doing what you think it is.
Mike






Borgelt Instruments - design & manufacture 
of quality soaring instrumentation since 1978

<http://www.borgeltinstruments.com/>www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 :  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[glenn_mc]

Hi MikeI  usually fly with a bit of top rudder in thetmals i.e. string pointing 
towards uppermost wing. It prevents being blown out of the lift in gusty 
thermals and is useful when down low scratching away.CheersGlenn


Sent from my SAMSUNG Galaxy Note5 on the Telstra Mobile Network
 Original message From: Mike Borgelt 
 Date: 17/1/19  10:42 am  (GMT+10:00) To: 
"Discussion of issues relating to Soaring in Australia." 
 Subject: Re: [Aus-soaring] slip in thermals? 

5 replies and nobody wants to say what they personally try to do or
why.


Never mind.




Mike










At 09:39 AM 1/17/2019, you wrote:

Good morning all

You might want to refer to "Advanced Soaring Made Easy" pages
194 and 195.

Cheers

Bernard





Sent from my Samsung Galaxy smartphone.


 Original message 

From: Bob Dircks  

Date: 17/01/2019 10:03 (GMT+09:30) 

To: "Discussion of issues relating to Soaring in Australia."
 

Subject: Re: [Aus-soaring] slip in thermals? 


Good points Richard,


However I still find the use of the word "pointing" very
ambiguous. 


I suggest that "pointing" indicates a direction radiating from
the viewpoint. 

This would have us discussing the forward direction of the string, 
while it is more common to consider the rearward direction of the
string. ie it's trailing direction. 





On Thu, 17 Jan. 2019, 10:18 am Richard Frawley

wrote:



Mike,


In your original question,



Part b,



By "pointing" I presume you mean "trailing"
?



To me, in this case "pointing" could be the direction of
the forward end of the string. 





On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt
<
mborg...@borgeltinstruments.com wrote:



So how about answering the questions?





Mike



At 08:51 AM 1/17/2019, you wrote:


and what is the expected differential (gain/loss) with say a 10degree
slip indication variation, given all the other factors that determine
climb rate.



This might b able to be worked out mathematically given the airflows
angle on the wing and fuselage drags differences



I suspect that are several aerodynamic factors would have to be
considered, especially given the the thermal core is dynamic.



A question for modern designers perhaps, especially when all aviation
design is a trade off

















Richard Frawley


rjfraw...@gmail.com



We do not inherit the earth from our ancestors, we borrow it from our
children












On 17 Jan 2019, at 9:43 am, Mike Borgelt
<
mborg...@borgeltinstruments.com> wrote:



At 07:36 AM 1/17/2019, you wrote:


Perhaps the more important question is how to you tell if one
technique is better than another. What is a useful
baseline?






Climbing better than the other gliders is the test but what if
everybody is using the same less than optimum technique?



Mike











On 17 Jan 2019, at 7:16 am, Mike Borgelt
<
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you 


a) keep the string centered


b) fly with it pointing to the outside of the turn


c) why?





Your technique may not be doing what you think it is.



Mike











Borgelt
Instruments - design
& manufacture of quality soaring instrumentation since 1978




www.borgeltinstruments.com


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int+61-7-4635 5784


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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

See my post at 11:13 Harry.

Mike

At 12:26 PM 1/17/2019, you wrote:

Hi All,

The answer as to why we thermal with the yaw 
string slightly outwards might have something to 
with the fact we are flying a straight glider in 
a curved pattern. If the glider had the same 
curved shape as the thermals diameter the yaw 
string would be central in a  balanced turn. As 
the string is well to the front of the central 
part of the glider it will be slightly outwards 
when a yaw string centrally located 
longitudinally would be straight at the same 
time. Haven't worked out just how many degrees 
and am sure Mike will shoot this explanation 
down in flames but maybe worth a thought,


Harry




On 17/01/2019 7:16 AM, Mike Borgelt wrote:


When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of 
quality soaring instrumentation since 1978

www.borgeltinstruments.com
tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[harry medlicott]

Hi All,

The answer as to why we thermal with the yaw string slightly outwards 
might have something to with the fact we are flying a straight glider in 
a curved pattern. If the glider had the same curved shape as the 
thermals diameter the yaw string would be central in a  balanced turn. 
As the string is well to the front of the central part of the glider it 
will be slightly outwards when a yaw string centrally located 
longitudinally would be straight at the same time. Haven't worked out 
just how many degrees and am sure Mike will shoot this explanation down 
in flames but maybe worth a thought,


Harry




On 17/01/2019 7:16 AM, Mike Borgelt wrote:


When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






*Borgelt Instruments***- /design & manufacture of quality soaring 
instrumentation since 1978

/ www.borgeltinstruments.com
tel:   07 4635 5784 overseas: 
int+61-7-4635 5784

mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia



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Re: [Aus-soaring] slip in thermals?

[Erich Wittstock]

Hello Mike,
*When circling in a thermal, do you *
*a) keep the string centered*
*b) fly with it pointing to the outside of the turn*
*c) why?*

OK, the image of the string off centre is exaggerated in Dick Johnson's
picture and drawing.
The marks on the canopy might suit the *e*ta.
As Reg stated: *"I have the free end of the string pointing a few degrees
to the outside of the turn."*
That's what I do as well.
In a two-seater, the front string, being approximately 100mm long is
pointing approximately 3mm to the outside of the turn when established in a
thermal.
The rear seat string points less to the outside in that situation.
Similar for a single seater.
The slip indicator is also perfectly located in the centre during these
turns - when the string is a few degrees to the outside.
Another cue for flying clean is that the noise is the lowest and even from
both sides of the wing root where the tape dislodged evenly.
(Although that's not a clean wing root and not "clean flying" as a result -
but it happens in club trainers.)

Hope this explains better my theory and experience on that matter.
thank you
Erich

Here is another point for discussion: passengers are more likely to
experience air sickness when the string is in the centre during turns.
I usually add a few extra mm of "string out" during passenger flights with
excellent results so far.






On Thu, 17 Jan 2019 at 12:30, Reg Moore  wrote:

> I have the free end of the string pointing a few degrees to the outside of
> the turn.
>
> On 17 Jan 2019, at 9:42 am, Bob Dircks  wrote:
>
> Mike,
> In your original question,
>
> Part b,
>
> By "pointing" I presume you mean "trailing" ?
>
> To me, in this case "pointing" could be the direction of the forward end
> of the string.
>
>
> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt <
> mborg...@borgeltinstruments.com wrote:
>
>> So how about answering the questions?
>>
>>
>> Mike
>>
>> At 08:51 AM 1/17/2019, you wrote:
>>
>> and what is the expected differential (gain/loss) with say a 10degree
>> slip indication variation, given all the other factors that determine climb
>> rate.
>>
>> This might b able to be worked out mathematically given the airflows
>> angle on the wing and fuselage drags differences
>>
>> I suspect that are several aerodynamic factors would have to be
>> considered, especially given the the thermal core is dynamic.
>>
>> A question for modern designers perhaps, especially when all aviation
>> design is a trade off
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Richard Frawley
>> rjfraw...@gmail.com
>>
>> We do not inherit the earth from our ancestors, we borrow it from our
>> children
>>
>>
>>
>>
>>
>>
>>
>> On 17 Jan 2019, at 9:43 am, Mike Borgelt <
>> mborg...@borgeltinstruments.com> wrote:
>>
>> At 07:36 AM 1/17/2019, you wrote:
>>
>> Perhaps the more important question is how to you tell if one technique
>> is better than another. What is a useful baseline?
>>
>>
>>
>>
>>
>> Climbing better than the other gliders is the test but what if everybody
>> is using the same less than optimum technique?
>>
>> Mike
>>
>>
>>
>>
>>
>>
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt <
>> mborg...@borgeltinstruments.com> wrote:
>>
>> When circling in a thermal, do you
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>>
>>
>> Your technique may not be doing what you think it is.
>>
>> Mike
>>
>>
>>
>>
>>
>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> ___
>> Aus-soaring mailing list
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>> http://lists.base64.com.au/listinfo/aus-soaring
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>> http://lists.base64.com.au/listinfo/aus-soaring
>>
>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
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>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> _

Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Thanks, Reg.


Mike


At 11:30 AM 1/17/2019, you wrote:
I have the free end of the string pointing a few degrees to the 
outside of the turn.


On 17 Jan 2019, at 9:42 am, Bob Dircks 
<dircks@gmail.com> wrote:



Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the direction of the 
forward end of the string.



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
<mborg...@borgeltinstruments.com wrote:

So how about answering the questions?


Mike

At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential (gain/loss) with say a 
10degree slip indication variation, given all the other factors 
that determine climb rate.


This might b able to be worked out mathematically given the 
airflows angle on the wing and fuselage drags differences


I suspect that are several aerodynamic factors would have to be 
considered, especially given the the thermal core is dynamic.


A question for modern designers perhaps, especially when all 
aviation design is a trade off











Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from 
our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:


At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how to you tell if one 
technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the test but what if 
everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of quality soaring 
instrumentation since 1978

www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 :  int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

At 11:14 AM 1/17/2019, you wrote:



This results in them feeling like "the tail is 
being pushed up" as they pull back. If you are 
turning  and the thermal is strong and you are 
too keen to maintain the attitude you can stall 
the wing(s), spin and try to kill yourself.


Really, and how often does that happen….must be trained otherwise then...




Try the accident with the ASG29 at Waikerie a 
couple of years ago as a candidate. Nobody I've 
talked to has seen an investigation report. 
Doesn't mean there isn't one. Also doesn't 
necessarily mean they came to valid conclusions.



The dynamically and statically lighter the 
tail is, the faster it will rise (it rises in 
response to the change of angle of attack 
caused by the rising air). The faster is rises the easier it is to feel.


A nose heavy CG slows the ‘rise’ 
response making it harder to feel the lift, 
this is most prominent when seeking bubbles and lines than big thermals.



Wrong way around. Forward C of G makes the glider more statically stable.


exactly what I said, a fwd CG means more 
positive force being applied on the tailplane 
(creating strong stability and resistance to 
external forces) and making the stick force 
required to change the A0A greater (giving the glider that heavy feel)


A rearward CG makes the controls lighter (which 
you can easily feel if the CG is back with the 
controls being lighter and more sensitive) and 
as such the dynamic forces in place are less, so 
when the plane goes into rising air the 
stabilising setup will renormalise the AoA by 
raising the tail more quickly than if it has a 
forward CG…ie less signalling to the pilot



You actually said (and quoted yourself) "A nose 
heavy CG slows the ‘rise’ response 
making it harder to feel the lift, this is most 
prominent when seeking bubbles and lines than big thermals."

The opposite of what you now claim. You are confused.
Run the C of G far enough back and the static 
stability will be zero. The glider will then not 
try to change attitude when encountering rising or sinking air.



A good question to ask is why have tailplanes 
got smaller and booms lighter and smaller. 
Easily seen by anything new from the factory of recent design



When there is less of it there is less wetted 
area and less drag. Horizontal tails  can be 
small on properly designed flapped gliders 
as  there may not be much lift force being 
generated unless changing attitude, if optimum flap settings are used.
The last competitive Standard Class glider to be 
designed was the Discus 2. We won't count the ASW 
28. Will anyone try to design, test and market another?


Mike






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Re: [Aus-soaring] slip in thermals?

[Reg Moore]

I have the free end of the string pointing a few degrees to the outside of the 
turn. 

> On 17 Jan 2019, at 9:42 am, Bob Dircks  wrote:
> 
> Mike,
> In your original question,
> 
> Part b,
> 
> By "pointing" I presume you mean "trailing" ?
> 
> To me, in this case "pointing" could be the direction of the forward end of 
> the string. 
> 
> 
>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt > wrote:
>> So how about answering the questions?
>> 
>> 
>> Mike
>> 
>> At 08:51 AM 1/17/2019, you wrote:
>>> and what is the expected differential (gain/loss) with say a 10degree slip 
>>> indication variation, given all the other factors that determine climb rate.
>>> 
>>> This might b able to be worked out mathematically given the airflows angle 
>>> on the wing and fuselage drags differences
>>> 
>>> I suspect that are several aerodynamic factors would have to be considered, 
>>> especially given the the thermal core is dynamic.
>>> 
>>> A question for modern designers perhaps, especially when all aviation 
>>> design is a trade off
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Richard Frawley
>>> rjfraw...@gmail.com
>>> 
>>> We do not inherit the earth from our ancestors, we borrow it from our 
>>> children
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
 On 17 Jan 2019, at 9:43 am, Mike Borgelt < 
 mborg...@borgeltinstruments.com> wrote:
 
 At 07:36 AM 1/17/2019, you wrote:
> Perhaps the more important question is how to you tell if one technique 
> is better than another. What is a useful baseline?
 
 
 
 
 Climbing better than the other gliders is the test but what if everybody 
 is using the same less than optimum technique?
 
 Mike
 
 
 
 
 
 
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < 
>> mborg...@borgeltinstruments.com> wrote:
>> 
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Your technique may not be doing what you think it is.
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
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 instrumentation since 1978
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Re: [Aus-soaring] slip in thermals?

[Anthony Smith]

The magnification of the sideslip angle effect is to do with the shape of
the fuselage / canopy and the airflow around it. It has nothing to do with
the boundary layer.  The effect will taper off as you get further from the
fuselage but will still be noticeable out to a fuselage diameter or so away
from the fuselage surface.

 

The same effect applies to the angle of attack probes on larger aircraft.
These are all calibrated for their position on the fuselage and the
calibration factor typically ranges from 1.6 up to 2.

 

Regards

 

Anthony

 

From: Mike Borgelt [mailto:mborg...@borgeltinstruments.com] 
Sent: Thursday, 17 January 2019 10:26 AM
To: Discussion of issues relating to Soaring in Australia.

Subject: Re: [Aus-soaring] slip in thermals?

 

Yes, I've seen that article, Erich.

A couple of months ago we ran a flight test of the theory that the string in
the boundary layer amplified the actual sideslip. Taped a bent paperclip
with a second string 25mm above the normal one.
The boundary layer a couple of feet from the nose is quite thin so this
should have got it outside the layer. 
Nope. Strings seemed to move together.

Need to do this again with several strings at different heights. The flow
disturbance may extend much further from the surface of the nose.

Mike


At 09:36 AM 1/17/2019, you wrote:



Hello Mike,
is this article useful?
http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf

ta
Erich


On Thu, 17 Jan 2019 at 07:16, Mike Borgelt < mborg...@borgeltinstruments.com
<mailto:mborg...@borgeltinstruments.com> > wrote:

When circling in a thermal, do you 

a) keep the string centered

b) fly with it pointing to the outside of the turn

c) why?



Your technique may not be doing what you think it is.

Mike







Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978

www.borgeltinstruments.com <http://www.borgeltinstruments.com/> 


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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

> That is because the glider actually accelerates momentarily on entering lift. 
> Draw the diagram and remember that the lift vector is at right angles to the 
> relative airflow. The time constant for this is around 0.5 seconds for a 
> modern ballasted glider so after a bit over a second most of the effect has 
> gone away.

Interesting that with model gliders, you can see the tail rise quite clearly. 
Same mechanics, just more amplified as the tails on HLG in particular, are very 
light.

If you watch a full size glider low and close to the field, when it meets 
rising air you can see the tail rise. Conversely you can also see when a glider 
is in sink…dragging its sorry arse all over the place,

Once this effect is bought to a pilots attention they can learn to recognise 
and respond appropriately . The vario however needs to be at very low volume so 
that the pilot is not swamped its distraction and preventing useful physical 
signals being recognised while waiting for the vario to bleep well after the 
aircraft has departed the rising air.

> Most people are flying attitude and will automatically pull the stick back to 
> maintain the attitude.

Unless they are attune themselves to the feeling they will miss it. Its a 
subtle signal that can be made more obvious by design and CoG placement


> This results in them feeling like "the tail is being pushed up" as they pull 
> back. If you are turning  and the thermal is strong and you are too keen to 
> maintain the attitude you can stall the wing(s), spin and try to kill 
> yourself.

Really, and how often does that happen….must be trained otherwise then...
> 
>> The dynamically and statically lighter the tail is, the faster it will rise 
>> (it rises in response to the change of angle of attack caused by the rising 
>> air). The faster is rises the easier it is to feel.
>> 
>> A nose heavy CG slows the ‘rise’ response making it harder to feel the 
>> lift, this is most prominent when seeking bubbles and lines than big 
>> thermals.
> 
> 
> Wrong way around. Forward C of G makes the glider more statically stable.

exactly what I said, a fwd CG means more positive force being applied on the 
tailplane (creating strong stability and resistance to external forces) and 
making the stick force required to change the A0A greater (giving the glider 
that heavy feel)

A rearward CG makes the controls lighter (which you can easily feel if the CG 
is back with the controls being lighter and more sensitive) and as such the 
dynamic forces in place are less, so when the plane goes into rising air the 
stabilising setup will renormalise the AoA by raising the tail more quickly 
than if it has a forward CG…ie less signalling to the pilot


> I was in Germany in 1988 when the SB13 flying wing glider flew. They were 
> pretty cautious and had a forward C of G and being a wing it had a low moment 
> of inertia around the C of G in the pitching direction. It proved unpleasant 
> to fly like that as it reacted too quickly to up and down gusts so they ran 
> the C of G aft to make the static stability more neutral.

Flying wings are like that. A short moment has its downsides. Building 
stability into single wing seems to have tradeoffs greater than employing a 
tailplane (which there days are tiny)

A good question to ask is why have tailplanes got smaller and booms lighter and 
smaller. Easily seen by anything new from the factory of recent design



> 
> Mike
> 
> 
> 
> 
> 
>> The diana 2 is know to be able to signal lift very well, this is likely why. 
>> (it has very low tail and boom mass, and less inertial and therefore faster 
>> to respond)
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> Richard Frawley
>> rjfraw...@gmail.com 
>> 
>> We do not inherit the earth from our ancestors, we borrow it from our 
>> children
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>>> On 17 Jan 2019, at 10:43 am, Nick Gilbert >>  > wrote:
>>> 
>>> Mike,
>>> 
>>> I’m sure this is the wrong answer, but to me it feels more comfortable 
>>> slightly nose high - so yawstring indicating right rudder required if 
>>> turning right. I fly with forward c of g which may be a factor. 
>>> 
>>> I have no idea if this is more or less efficient, and I’m under no 
>>> impression that it’s the optimal method. Just that it feels more 
>>> comfortable. 
>>> 
>>> Nick. 
>>> 
>>> On 17 Jan 2019, at 10:09 am, Mike Borgelt < mborg...@borgeltinstruments.com 
>>> > wrote:
>>> 
 Yes, to be pedantic it is trailing but common vernacular is to call the 
 back end of the yaw string  the direction it is pointing.
 
 Now can someone answer the questions please?
 
 When circling in a thermal, do you 
 a) keep the string centered
 b) fly with it pointing to the outside of the turn
 c) why?
 
 
 Mike
 
 At 09:12 AM 1/17/2019, you wrote:
> Mike,
> In your original question,
>

Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Hi Erich,

It is a pity Dick Johnson didn't do some numbers 
on the theory of the curved airflow.


A typical radius of a thermal turn at 60 KTAS is 
near as dammit 100 meters. With the yaw string 
location 2 meters (actually 1.5 on an A 
model  Ventus) this gives the angle offset at 
57.3 2/100  or about 1.15 degrees BUT the glider 
is banked at 45 degrees so what you see is this 
number multiplied by the cosine of the bank angle 
or 0.707. This gives a yaw string slip indication 
of  0.8 degrees. On a 60mm yaw string this is 
less than 1mm. Think you can see it? To get the 
angles of yaw string displacement Dick was 
talking about  (5 to 20 degrees) you need the 
business end of the string displaced from the 
center by 5 to 20 mm. This is a definite slip.


Now flying your beautifully streamlined fuselage 
optimised for minimum drag at zero yaw angle, 
somewhat sideways through the air WILL increase 
the  profile drag. Also it will generate induced 
drag (where do you think the side force comes 
from?) from a very low aspect ratio inefficient 
wing (the fuselage and vertical stabiliser).


Now draw the vector diagram of the forces in a 45 
degree banked turn. The side force generated by 
the slip points UP and to the OUTSIDE of the 
circle. This means that there is effectively less 
bank angle than you think and part of the lift 
generated is from the very inefficient 
fuselage/tail instead of that lovely efficient wing.


Sure you want to do that?

I understand the business of wanting to minimise 
the amount of aileron acting to hold off bank and 
on a Standard class glider the aileron deflection 
slightly upsets the lift distribution of the wing 
but on anything where the trailing edge or most 
of it moves, well that's why we have flaps - to 
maximise lift and minimise profile drag at the different lift coefficients.


Mike

At 09:36 AM 1/17/2019, you wrote:

Hello Mike,
is this article useful?
http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf
ta
Erich


On Thu, 17 Jan 2019 at 07:16, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of 
quality soaring instrumentation since 1978

www.borgeltinstruments.com
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

At 10:04 AM 1/17/2019, you wrote:

why not fly with a fwd CoG

I have read somewhere that the CG range offered 
in the manual still has a safety factor built 
in, so its pretty safe anywhere forward of 2/3rds back.


Here is an interesting point about CG.

There are two primary ways that the pilot senses lift

1) increasing pressure in the buttocks, lower 
spine and inner ear by vertical acceleration
2) by a change of the location of the horizon 
(the tail raises) and the eyes sense the change


The latter is interesting, as the mix of these 
two will result for some people in a sense lift 
as push forward or push in the back feeling.


That is because the glider actually accelerates 
momentarily on entering lift. Draw the diagram 
and remember that the lift vector is at right 
angles to the relative airflow. The time constant 
for this is around 0.5 seconds for a modern 
ballasted glider so after a bit over a second most of the effect has gone away.
Most people are flying attitude and will 
automatically pull the stick back to maintain the 
attitude. This results in them feeling like "the 
tail is being pushed up" as they pull back. If 
you are turning  and the thermal is strong and 
you are too keen to maintain the attitude you can 
stall the wing(s), spin and try to kill yourself.





The dynamically and statically lighter the tail 
is, the faster it will rise (it rises in 
response to the change of angle of attack caused 
by the rising air). The faster is rises the easier it is to feel.


A nose heavy CG slows the ‘rise’ response 
making it harder to feel the lift, this is most 
prominent when seeking bubbles and lines than big thermals.



Wrong way around. Forward C of G makes the glider 
more statically stable. I was in Germany in 1988 
when the SB13 flying wing glider flew. They were 
pretty cautious and had a forward C of G and 
being a wing it had a low moment of inertia 
around the C of G in the pitching direction. It 
proved unpleasant to fly like that as it reacted 
too quickly to up and down gusts so they ran the 
C of G aft to make the static stability more neutral.


Mike





The diana 2 is know to be able to signal lift 
very well, this is likely why. (it has very low 
tail and boom mass, and less inertial and therefore faster to respond)









Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







On 17 Jan 2019, at 10:43 am, Nick Gilbert 
<golfsierrag...@gmail.com> wrote:


Mike,

I’m sure this is the wrong answer, but to me 
it feels more comfortable slightly nose high - 
so yawstring indicating right rudder required 
if turning right. I fly with forward c of g which may be a factor.


I have no idea if this is more or less 
efficient, and I’m under no impression that 
it’s the optimal method. Just that it feels more comfortable.


Nick.

On 17 Jan 2019, at 10:09 am, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:


Yes, to be pedantic it is trailing but common 
vernacular is to call the back end of the yaw 
string  the direction it is pointing.


Now can someone answer the questions please?

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Mike

At 09:12 AM 1/17/2019, you wrote:

Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the 
direction of the forward end of the string.Â



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
< 
mborg...@borgeltinstruments.com wrote:

So how about answering the questions?

Mike
At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.
This might b able to be worked out 
mathematically given the airflows angle on 
the wing and fuselage drags differences
I suspect that are several aerodynamic 
factors would have to be considered, 
especially given the the thermal core is dynamic.
A question for modern designers perhaps, 
especially when all aviation design is a trade off










Richard Frawley
rjfraw...@gmail.com
We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:

At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how 
to you tell if one technique is better than another. What is a useful baseline?




Climbing better than the other gliders is 
the test but what if everybody is using the same less than optimum technique?

Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstr

Re: [Aus-soaring] slip in thermals?

[Bob Dircks]

Mike,

The string is not many degrees off horizontal. so I don't quite follow
a comparison with a vertical object.

Surely the term "trailing" is most appropriate,  as it not only describes
the physical situation, including its movement as a result of air flow
direction,  but also provides the left and right sense we refer to in
discussion.

Bob

On Thu, 17 Jan. 2019, 10:49 am Mike Borgelt  Bob,
>
> The thing is in front of you pivoted at the front which is at the bottom
> from your point of view.
> Stand a  pencil on your desk in front of you. Pivot it clockwise some
> degrees less than 90 about the point where it rests on the desk. Which
> direction is it pointing?
>
>
> I used to fly with a little slip in thermals as a result of some advice by
> George Moffat/ Klaus Holighaus/Dick Johnson.
>
> Some flight tests have made me realise what you are really doing here. I
> don't think it is good.
>
> Mike
>
>
>
>
>
>
>
>
>  At 09:33 AM 1/17/2019, you wrote:
>
> Good points Richard,
>
> However I still find the use of the word "pointing" very ambiguous.Â
>
> I suggest that "pointing" indicates a direction radiating from the
> viewpoint.Â
> This would have us discussing the forward direction of the string,  while
> it is more common to consider the rearward direction of the string. ie
> it's trailing direction.Â
>
>
>
> On Thu, 17 Jan. 2019, 10:18 am Richard Frawley  the string can be either pointing in to the thermal centre or pointing out
> away from the core
>
> there is some conjecture that with some aircraft (I read that it was
> mainly older pre-1980 craft) that with the string pointing to the outside,
> they may be more efficient in the climb.
>
> There are also some views that say that polyhedral vs straight wings tend
> to set up a balance that has the string pointing out.
>
> I have not yet seen any empiric data or detailed theory that speaks to
> these suppositions, I expect it exists somewhere tho.
>
> More questions and less answers still…..
>
>
>
>
>
>
>
>
> Richard Frawley
> rjfraw...@gmail.com
>
> We do not inherit the earth from our ancestors, we borrow it from
> our children
>
>
>
>
>
>
>
> On 17 Jan 2019, at 10:12 am, Bob Dircks  wrote:
>
> Mike,
> In your original question,
>
> Part b,
>
> By "pointing" I presume you mean "trailing" ?
>
> To me, in this case "pointing" could be the direction of the forward end
> of the string.Â
>
>
> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt <
> mborg...@borgeltinstruments.com wrote:
> So how about answering the questions?
>
>
> Mike
>
> At 08:51 AM 1/17/2019, you wrote:
>
> and what is the expected differential (gain/loss) with say a 10degree slip
> indication variation, given all the other factors that determine climb rate.
>
> This might b able to be worked out mathematically given the airflows angle
> on the wing and fuselage drags differences
>
> I suspect that are several aerodynamic factors would have to be
> considered, especially given the the thermal core is dynamic.
>
> A question for modern designers perhaps, especially when all aviation
> design is a trade off
>
>
>
>
>
>
>
>
>
>
> Richard Frawley
> rjfraw...@gmail.com
>
> We do not inherit the earth from our ancestors, we borrow it from our
> children
>
>
>
>
>
>
>
> On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com>
> wrote:
>
> At 07:36 AM 1/17/2019, you wrote:
>
> Perhaps the more important question is how to you tell if one technique is
> better than another. What is a useful baseline?
>
>
>
>
>
> Climbing better than the other gliders is the test but what if everybody
> is using the same less than optimum technique?
>
> Mike
>
>
>
>
>
>
> On 17 Jan 2019, at 7:16 am, Mike Borgelt < mborg...@borgeltinstruments.com>
> wrote:
>
> When circling in a thermal, do you
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
>
>
> Your technique may not be doing what you think it is.
>
> Mike
>
>
>
>
>
>
> Borgelt Instruments - design & manufacture of quality soaring
> instrumentation since 1978
> www.borgeltinstruments.com
> tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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>
> Borgelt Instruments - design & manufacture of quality soaring
> instrumentation since 1978
> www.borgeltinstruments.com
> tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Thanks, Nick.



Mike


At 09:43 AM 1/17/2019, you wrote:

Mike,

I’m sure this is the wrong answer, but to me 
it feels more comfortable slightly nose high - 
so yawstring indicating right rudder required if 
turning right. I fly with forward c of g which may be a factor.


I have no idea if this is more or less 
efficient, and I’m under no impression that 
it’s the optimal method. Just that it feels more comfortable.


Nick.

On 17 Jan 2019, at 10:09 am, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:


Yes, to be pedantic it is trailing but common 
vernacular is to call the back end of the yaw 
string  the direction it is pointing.


Now can someone answer the questions please?

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Mike

At 09:12 AM 1/17/2019, you wrote:

Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the 
direction of the forward end of the string.Â



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
< 
mborg...@borgeltinstruments.com wrote:

So how about answering the questions?

Mike
At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.
This might b able to be worked out 
mathematically given the airflows angle on 
the wing and fuselage drags differences
I suspect that are several aerodynamic 
factors would have to be considered, 
especially given the the thermal core is dynamic.
A question for modern designers perhaps, 
especially when all aviation design is a trade off










Richard Frawley
rjfraw...@gmail.com
We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:

At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how 
to you tell if one technique is better than another. What is a useful baseline?




Climbing better than the other gliders is 
the test but what if everybody is using the same less than optimum technique?

Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?

Your technique may not be doing what you think it is.
Mike






Borgelt Instruments - design & manufacture 
of quality soaring instrumentation since 1978

www.borgeltinstruments.com
tel:Â Â  07 4635 5784Â Â Â Â 
 overseas: int+61-7-4635 5784
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

these days the computer simulation models could give a descent indication.

as the difference could be small, we might all be wasting time chasing a bit of 
fluff




Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







> On 17 Jan 2019, at 10:55 am, Mike Borgelt  
> wrote:
> 
> Yes, I've seen that article, Erich.
> 
> A couple of months ago we ran a flight test of the theory that the string in 
> the boundary layer amplified the actual sideslip. Taped a bent paperclip with 
> a second string 25mm above the normal one.
> The boundary layer a couple of feet from the nose is quite thin so this 
> should have got it outside the layer. 
> Nope. Strings seemed to move together.
> 
> Need to do this again with several strings at different heights. The flow 
> disturbance may extend much further from the surface of the nose.
> 
> Mike
> 
> 
> At 09:36 AM 1/17/2019, you wrote:
>> Hello Mike,
>> is this article useful?
>> http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf 
>> 
>>  
>> ta
>> Erich
>> 
>> 
>> On Thu, 17 Jan 2019 at 07:16, Mike Borgelt < mborg...@borgeltinstruments.com 
>> > wrote:
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Your technique may not be doing what you think it is.
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com
>>  
>> tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
>> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>> ___
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>> http://lists.base64.com.au/listinfo/aus-soaring 
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>> 
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>> design & manufacture of quality soaring instrumentation since 1978
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> int+61-7-4635 5784
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

why not fly with a fwd CoG

I have read somewhere that the CG range offered in the manual still has a 
safety factor built in, so its pretty safe anywhere forward of 2/3rds back.

Here is an interesting point about CG.

There are two primary ways that the pilot senses lift

1) increasing pressure in the buttocks, lower spine and inner ear by vertical 
acceleration
2) by a change of the location of the horizon (the tail raises) and the eyes 
sense the change

The latter is interesting, as the mix of these two will result for some people 
in a sense lift as push forward or push in the back feeling.

The dynamically and statically lighter the tail is, the faster it will rise (it 
rises in response to the change of angle of attack caused by the rising air). 
The faster is rises the easier it is to feel.

A nose heavy CG slows the ‘rise’ response making it harder to feel the lift, 
this is most prominent when seeking bubbles and lines than big thermals.

The diana 2 is know to be able to signal lift very well, this is likely why. 
(it has very low tail and boom mass, and less inertial and therefore faster to 
respond)








Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







> On 17 Jan 2019, at 10:43 am, Nick Gilbert  wrote:
> 
> Mike,
> 
> I’m sure this is the wrong answer, but to me it feels more comfortable 
> slightly nose high - so yawstring indicating right rudder required if turning 
> right. I fly with forward c of g which may be a factor. 
> 
> I have no idea if this is more or less efficient, and I’m under no impression 
> that it’s the optimal method. Just that it feels more comfortable. 
> 
> Nick. 
> 
> On 17 Jan 2019, at 10:09 am, Mike Borgelt  > wrote:
> 
>> Yes, to be pedantic it is trailing but common vernacular is to call the back 
>> end of the yaw string  the direction it is pointing.
>> 
>> Now can someone answer the questions please?
>> 
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Mike
>> 
>> At 09:12 AM 1/17/2019, you wrote:
>>> Mike,
>>> In your original question,
>>> 
>>> Part b,
>>> 
>>> By "pointing" I presume you mean "trailing" ?
>>> 
>>> To me, in this case "pointing" could be the direction of the forward end of 
>>> the string. 
>>> 
>>> 
>>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt < 
>>> mborg...@borgeltinstruments.com  
>>> wrote:
>>> So how about answering the questions?
>>> 
>>> 
>>> Mike
>>> 
>>> At 08:51 AM 1/17/2019, you wrote:
 and what is the expected differential (gain/loss) with say a 10degree slip 
 indication variation, given all the other factors that determine climb 
 rate.
 
 This might b able to be worked out mathematically given the airflows angle 
 on the wing and fuselage drags differences
 
 I suspect that are several aerodynamic factors would have to be 
 considered, especially given the the thermal core is dynamic.
 
 A question for modern designers perhaps, especially when all aviation 
 design is a trade off
 
 
 
 
 
 
 
 
 
 
 Richard Frawley
 rjfraw...@gmail.com 
 
 We do not inherit the earth from our ancestors, we borrow it from our 
 children
 
 
 
 
 
 
 
> On 17 Jan 2019, at 9:43 am, Mike Borgelt < 
> mborg...@borgeltinstruments.com > 
> wrote:
> 
> At 07:36 AM 1/17/2019, you wrote:
>> Perhaps the more important question is how to you tell if one technique 
>> is better than another. What is a useful baseline?
> 
> 
> 
> 
> Climbing better than the other gliders is the test but what if everybody 
> is using the same less than optimum technique?
> 
> Mike
> 
> 
> 
> 
> 
> 
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < 
>> mborg...@borgeltinstruments.com 
>> > wrote:
>> 
>>> When circling in a thermal, do you 
>>> a) keep the string centered
>>> b) fly with it pointing to the outside of the turn
>>> c) why?
>>> 
>>> 
>>> Your technique may not be doing what you think it is.
>>> 
>>> Mike
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Borgelt Instruments - design & manufacture of quality soaring 
>>> instrumentation since 1978
>>> www.borgeltinstruments.com 
>>> tel:Â  Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
>>> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
>>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>>> ___
>>> Aus-soaring mailing list
>>> Aus-soari

Re: [Aus-soaring] slip in thermals?

[DMcD]

>>5 replies and nobody wants to say what they personally try to do or why.

I fly with the string pointing slightly out of the turn. I do this
because the glider seems to balance nicely that way and require less
control input. I don't think the glider climbs any more slowly because
of this.

SFAIK, the original theory and article was written by Holighaus K.

www.wisoar.org/Documents/Holighaus - Thermalling Efficiency.pdf

However, I only would use that as a justification for thermalling with
the yaw string not centred :-)

In any published photographs, where the yaw string is not central, I'd
normally correct so people don't moan.

D
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Yes, I've seen that article, Erich.

A couple of months ago we ran a flight test of 
the theory that the string in the boundary layer 
amplified the actual sideslip. Taped a bent 
paperclip with a second string 25mm above the normal one.
The boundary layer a couple of feet from the nose 
is quite thin so this should have got it outside the layer.

Nope. Strings seemed to move together.

Need to do this again with several strings at 
different heights. The flow disturbance may 
extend much further from the surface of the nose.


Mike


At 09:36 AM 1/17/2019, you wrote:

Hello Mike,
is this article useful?
http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf
ta
Erich


On Thu, 17 Jan 2019 at 07:16, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of 
quality soaring instrumentation since 1978

www.borgeltinstruments.com
tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

is the theory that supports that scientifically tested and to my earlier point 
it is worth the focus tax?


> On 17 Jan 2019, at 10:39 am, eckey  wrote:
> 
> Good morning all
> You might want to refer to "Advanced Soaring Made Easy" pages 194 and 195.
> Cheers
> Bernard
> 
> 
> 
> Sent from my Samsung Galaxy smartphone.
> 
>  Original message 
> From: Bob Dircks 
> Date: 17/01/2019 10:03 (GMT+09:30)
> To: "Discussion of issues relating to Soaring in Australia." 
> 
> Subject: Re: [Aus-soaring] slip in thermals?
> 
> Good points Richard,
> 
> However I still find the use of the word "pointing" very ambiguous. 
> 
> I suggest that "pointing" indicates a direction radiating from the viewpoint. 
> This would have us discussing the forward direction of the string,  while it 
> is more common to consider the rearward direction of the string. ie it's 
> trailing direction. 
> 
> 
> 
> On Thu, 17 Jan. 2019, 10:18 am Richard Frawley  <mailto:rjfraw...@gmail.com> wrote:
> the string can be either pointing in to the thermal centre or pointing out 
> away from the core
> 
> there is some conjecture that with some aircraft (I read that it was mainly 
> older pre-1980 craft) that with the string pointing to the outside, they may 
> be more efficient in the climb.
> 
> There are also some views that say that polyhedral vs straight wings tend to 
> set up a balance that has the string pointing out.
> 
> I have not yet seen any empiric data or detailed theory that speaks to these 
> suppositions, I expect it exists somewhere tho.
> 
> More questions and less answers still…..
> 
> 
> 
> 
> 
> 
> 
> 
> Richard Frawley
> rjfraw...@gmail.com <mailto:rjfraw...@gmail.com>
> 
> We do not inherit the earth from our ancestors, we borrow it from our children
> 
> 
> 
> 
> 
> 
> 
>> On 17 Jan 2019, at 10:12 am, Bob Dircks > <mailto:dircks@gmail.com>> wrote:
>> 
>> Mike,
>> In your original question,
>> 
>> Part b,
>> 
>> By "pointing" I presume you mean "trailing" ?
>> 
>> To me, in this case "pointing" could be the direction of the forward end of 
>> the string. 
>> 
>> 
>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt > <mailto:mborg...@borgeltinstruments.com> wrote:
>> So how about answering the questions?
>> 
>> 
>> Mike
>> 
>> At 08:51 AM 1/17/2019, you wrote:
>>> and what is the expected differential (gain/loss) with say a 10degree slip 
>>> indication variation, given all the other factors that determine climb rate.
>>> 
>>> This might b able to be worked out mathematically given the airflows angle 
>>> on the wing and fuselage drags differences
>>> 
>>> I suspect that are several aerodynamic factors would have to be considered, 
>>> especially given the the thermal core is dynamic.
>>> 
>>> A question for modern designers perhaps, especially when all aviation 
>>> design is a trade off
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Richard Frawley
>>> rjfraw...@gmail.com <mailto:rjfraw...@gmail.com>
>>> 
>>> We do not inherit the earth from our ancestors, we borrow it from our 
>>> children
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com 
>>>> <mailto:mborg...@borgeltinstruments.com>> wrote:
>>>> 
>>>> At 07:36 AM 1/17/2019, you wrote:
>>>>> Perhaps the more important question is how to you tell if one technique 
>>>>> is better than another. What is a useful baseline?
>>>> 
>>>> 
>>>> 
>>>> 
>>>> Climbing better than the other gliders is the test but what if everybody 
>>>> is using the same less than optimum technique?
>>>> 
>>>> Mike
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < 
>>>>> mborg...@borgeltinstruments.com <mailto:mborg...@borgeltinstruments.com>> 
>>>>> wrote:
>>>>> 
>>>>>> When circling in a thermal, do you 
>>>>>> a) keep the string centered
>>>>>> b) fly with it pointing to the outside o

Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

To earlier point, this is an old article and we have seen massive improvements 
in aircraft design and resulting performance. What is no longer relevant?

I had the experience recently of flying three different Duo Discus.

Each one required very different control input to keep a so called balanced 
turn (string appox centered)

In one of them, a noticeable amount of aileron and rudder (crossed and 
constant) input was required, the other two less so but some.

Given that control input = drag, is it better to have that drag and keen the 
string in the center or reduce the input and let the string swing out?

Why was it so different between the same design of plane?







> On 17 Jan 2019, at 10:36 am, Erich Wittstock  wrote:
> 
> Hello Mike,
> is this article useful?
> http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf 
> 
> ta
> Erich
> 
> 
> On Thu, 17 Jan 2019 at 07:16, Mike Borgelt  > wrote:
> When circling in a thermal, do you 
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
> 
> 
> Your technique may not be doing what you think it is.
> 
> Mike
> 
> 
> 
> 
> 
> 
> Borgelt Instruments - design & manufacture of quality soaring instrumentation 
> since 1978
> www.borgeltinstruments.com
>  tel:   07 4635 5784 overseas: 
> int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> 
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Bob,

The thing is in front of you pivoted at the front 
which is at the bottom from your point of view.
Stand a  pencil on your desk in front of you. 
Pivot it clockwise some degrees less than 90 
about the point where it rests on the desk. Which direction is it pointing?



I used to fly with a little slip in thermals as a 
result of some advice by George Moffat/ Klaus Holighaus/Dick Johnson.


Some flight tests have made me realise what you 
are really doing here. I don't think it is good.


Mike








 At 09:33 AM 1/17/2019, you wrote:

Good points Richard,

However I still find the use of the word "pointing" very ambiguous.Â

I suggest that "pointing" indicates a direction 
radiating from the viewpoint.Â
This would have us discussing the forward 
direction of the string,  while it is more 
common to consider the rearward direction of the 
string. ie it's trailing direction.Â




On Thu, 17 Jan. 2019, 10:18 am Richard Frawley 
<rjfraw...@gmail.com wrote:
the string can be either pointing in to the 
thermal centre or pointing out away from the core


there is some conjecture that with some aircraft 
(I read that it was mainly older pre-1980 craft) 
that with the string pointing to the outside, 
they may be more efficient in the climb.


There are also some views that say that 
polyhedral vs straight wings tend to set up a 
balance that has the string pointing out.


I have not yet seen any empiric data or detailed 
theory that speaks to these suppositions, I expect it exists somewhere tho.


More questions and less answers still…..








Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 10:12 am, Bob Dircks 
<dircks@gmail.com> wrote:


Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the 
direction of the forward end of the string.Â



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
<mborg...@borgeltinstruments.com wrote:

So how about answering the questions?


Mike

At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.


This might b able to be worked out 
mathematically given the airflows angle on the 
wing and fuselage drags differences


I suspect that are several aerodynamic factors 
would have to be considered, especially given the the thermal core is dynamic.


A question for modern designers perhaps, 
especially when all aviation design is a trade off











Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:


At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how 
to you tell if one technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the 
test but what if everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture 
of quality soaring instrumentation since 1978

www.borgeltinstruments.com
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Re: [Aus-soaring] slip in thermals?

[Nick Gilbert]

Mike,

I’m sure this is the wrong answer, but to me it feels more comfortable slightly 
nose high - so yawstring indicating right rudder required if turning right. I 
fly with forward c of g which may be a factor. 

I have no idea if this is more or less efficient, and I’m under no impression 
that it’s the optimal method. Just that it feels more comfortable. 

Nick. 

> On 17 Jan 2019, at 10:09 am, Mike Borgelt  
> wrote:
> 
> Yes, to be pedantic it is trailing but common vernacular is to call the back 
> end of the yaw string  the direction it is pointing.
> 
> Now can someone answer the questions please?
> 
> When circling in a thermal, do you 
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
> 
> 
> Mike
> 
> At 09:12 AM 1/17/2019, you wrote:
>> Mike,
>> In your original question,
>> 
>> Part b,
>> 
>> By "pointing" I presume you mean "trailing" ?
>> 
>> To me, in this case "pointing" could be the direction of the forward end of 
>> the string. 
>> 
>> 
>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt < mborg...@borgeltinstruments.com 
>> wrote:
>> So how about answering the questions?
>> 
>> 
>> Mike
>> 
>> At 08:51 AM 1/17/2019, you wrote:
>>> and what is the expected differential (gain/loss) with say a 10degree slip 
>>> indication variation, given all the other factors that determine climb rate.
>>> 
>>> This might b able to be worked out mathematically given the airflows angle 
>>> on the wing and fuselage drags differences
>>> 
>>> I suspect that are several aerodynamic factors would have to be considered, 
>>> especially given the the thermal core is dynamic.
>>> 
>>> A question for modern designers perhaps, especially when all aviation 
>>> design is a trade off
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Richard Frawley
>>> rjfraw...@gmail.com
>>> 
>>> We do not inherit the earth from our ancestors, we borrow it from our 
>>> children
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
 On 17 Jan 2019, at 9:43 am, Mike Borgelt < 
 mborg...@borgeltinstruments.com> wrote:
 
 At 07:36 AM 1/17/2019, you wrote:
> Perhaps the more important question is how to you tell if one technique 
> is better than another. What is a useful baseline?
 
 
 
 
 Climbing better than the other gliders is the test but what if everybody 
 is using the same less than optimum technique?
 
 Mike
 
 
 
 
 
 
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < 
>> mborg...@borgeltinstruments.com> wrote:
>> 
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Your technique may not be doing what you think it is.
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com
>> tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
>> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
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> ___ Aus-soaring mailing list 
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> http://lists.base64.com.au/listinfo/aus-soaring
 
 Borgelt Instruments - design & manufacture of quality soaring 
 instrumentation since 1978
 www.borgeltinstruments.com
 tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
 mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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 Aus-soaring@lists.base64.com.au
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>>> 
>>> ___ Aus-soaring mailing list 
>>> Aus-soaring@lists.base64.com.au 
>>> http://lists.base64.com.au/listinfo/aus-soaring
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com
>> tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
>> mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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> Borgelt Instruments - design & manufacture of quality soaring instrumentation 
> since 1978
> www.borgeltinstr

Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

5 replies and nobody wants to say what they personally try to do or why.

Never mind.


Mike






At 09:39 AM 1/17/2019, you wrote:

Good morning all
You might want to refer to "Advanced Soaring Made Easy" pages 194 and 195.
Cheers
Bernard



Sent from my Samsung Galaxy smartphone.

 Original message 
From: Bob Dircks 
Date: 17/01/2019 10:03 (GMT+09:30)
To: "Discussion of issues relating to Soaring in 
Australia." 

Subject: Re: [Aus-soaring] slip in thermals?

Good points Richard,

However I still find the use of the word "pointing" very ambiguous.

I suggest that "pointing" indicates a direction radiating from the viewpoint.
This would have us discussing the forward 
direction of the string,  while it is more 
common to consider the rearward direction of the 
string. ie it's trailing direction.




On Thu, 17 Jan. 2019, 10:18 am Richard Frawley 
<<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com wrote:
the string can be either pointing in to the 
thermal centre or pointing out away from the core


there is some conjecture that with some aircraft 
(I read that it was mainly older pre-1980 craft) 
that with the string pointing to the outside, 
they may be more efficient in the climb.


There are also some views that say that 
polyhedral vs straight wings tend to set up a 
balance that has the string pointing out.


I have not yet seen any empiric data or detailed 
theory that speaks to these suppositions, I expect it exists somewhere tho.


More questions and less answers still…..
<







Richard Frawley
<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







On 17 Jan 2019, at 10:12 am, Bob Dircks 
<<mailto:dircks@gmail.com>dircks@gmail.com> wrote:


Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the 
direction of the forward end of the string.



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com>mborg...@borgeltinstruments.com wrote:

So how about answering the questions?


Mike

At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.


This might b able to be worked out 
mathematically given the airflows angle on the 
wing and fuselage drags differences


I suspect that are several aerodynamic factors 
would have to be considered, especially given the the thermal core is dynamic.


A question for modern designers perhaps, 
especially when all aviation design is a trade off











Richard Frawley
<mailto:rjfraw...@gmail.com>rjfraw...@gmail.com

We do not inherit the earth from our 
ancestors, we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com> 
mborg...@borgeltinstruments.com> wrote:


At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how 
to you tell if one technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the 
test but what if everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
<<mailto:mborg...@borgeltinstruments.com> 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture 
of quality soaring instrumentation since 1978

<http://www.borgeltinstruments.com/>www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 :  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[eckey]

Good morning allYou might want to refer to "Advanced Soaring Made Easy" pages 
194 and 195.CheersBernard


Sent from my Samsung Galaxy smartphone.
 Original message From: Bob Dircks  Date: 
17/01/2019  10:03  (GMT+09:30) To: "Discussion of issues relating to Soaring in 
Australia."  Subject: Re: [Aus-soaring] slip 
in thermals? 
Good points Richard,
However I still find the use of the word "pointing" very ambiguous. 
I suggest that "pointing" indicates a direction radiating from the viewpoint. 
This would have us discussing the forward direction of the string,  while it is 
more common to consider the rearward direction of the string. ie it's 
trailing direction. 


On Thu, 17 Jan. 2019, 10:18 am Richard Frawley  wrote:
Mike,In your original question,
Part b,
By "pointing" I presume you mean "trailing" ?
To me, in this case "pointing" could be the direction of the forward end of the 
string. 

On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt  wrote:


At 07:36 AM 1/17/2019, you wrote:

Perhaps the more important
question is how to you tell if one technique is better than another. What
is a useful baseline?





Climbing better than the other gliders is the test but what if everybody
is using the same less than optimum technique?


Mike










On 17 Jan 2019, at 7:16 am, Mike
Borgelt <
mborg...@borgeltinstruments.com> wrote:


When circling in a thermal, do
you 

a) keep the string centered

b) fly with it pointing to the outside of the turn

c) why?




Your technique may not be doing what you think it is.


Mike










Borgelt Instruments
- design & manufacture of quality soaring
instrumentation since 1978



www.borgeltinstruments.com

tel:   07 4635
5784 overseas: int+61-7-4635
5784

mob: 042835
5784
: 
int+61-42835 5784

P O Box 4607, Toowoomba East, QLD 4350, Australia 

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5784 overseas: int+61-7-4635
5784

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5784
: 
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5784 overseas: int+61-7-4635
5784

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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

Yes, to be pedantic it is trailing but common 
vernacular is to call the back end of the yaw 
string  the direction it is pointing.


Now can someone answer the questions please?

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Mike

At 09:12 AM 1/17/2019, you wrote:

Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the 
direction of the forward end of the string.Â



On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt 
<mborg...@borgeltinstruments.com wrote:

So how about answering the questions?


Mike

At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential 
(gain/loss) with say a 10degree slip indication 
variation, given all the other factors that determine climb rate.


This might b able to be worked out 
mathematically given the airflows angle on the 
wing and fuselage drags differences


I suspect that are several aerodynamic factors 
would have to be considered, especially given the the thermal core is dynamic.


A question for modern designers perhaps, 
especially when all aviation design is a trade off











Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, 
we borrow it from our children








On 17 Jan 2019, at 9:43 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:


At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how to 
you tell if one technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the 
test but what if everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture 
of quality soaring instrumentation since 1978

www.borgeltinstruments.com
tel:Â Â  07 4635 5784Â Â Â Â Â overseas: int+61-7-4635 5784
mob: 042835 5784Â Â Â Â Â Â Â Â  Â Â Â Â Â Â Â Â :Â  int+61-42835 5784
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

Swing in
Swing out

less ambiguous?

Swing infers a pivot point does it not?

> On 17 Jan 2019, at 10:33 am, Bob Dircks  wrote:
> 
> Good points Richard,
> 
> However I still find the use of the word "pointing" very ambiguous. 
> 
> I suggest that "pointing" indicates a direction radiating from the viewpoint. 
> This would have us discussing the forward direction of the string,  while it 
> is more common to consider the rearward direction of the string. ie it's 
> trailing direction. 
> 
> 
> 
> On Thu, 17 Jan. 2019, 10:18 am Richard Frawley   wrote:
> the string can be either pointing in to the thermal centre or pointing out 
> away from the core
> 
> there is some conjecture that with some aircraft (I read that it was mainly 
> older pre-1980 craft) that with the string pointing to the outside, they may 
> be more efficient in the climb.
> 
> There are also some views that say that polyhedral vs straight wings tend to 
> set up a balance that has the string pointing out.
> 
> I have not yet seen any empiric data or detailed theory that speaks to these 
> suppositions, I expect it exists somewhere tho.
> 
> More questions and less answers still…..
> 
> 
> 
> 
> 
> 
> 
> 
> Richard Frawley
> rjfraw...@gmail.com 
> 
> We do not inherit the earth from our ancestors, we borrow it from our children
> 
> 
> 
> 
> 
> 
> 
>> On 17 Jan 2019, at 10:12 am, Bob Dircks > > wrote:
>> 
>> Mike,
>> In your original question,
>> 
>> Part b,
>> 
>> By "pointing" I presume you mean "trailing" ?
>> 
>> To me, in this case "pointing" could be the direction of the forward end of 
>> the string. 
>> 
>> 
>> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt >  wrote:
>> So how about answering the questions?
>> 
>> 
>> Mike
>> 
>> At 08:51 AM 1/17/2019, you wrote:
>>> and what is the expected differential (gain/loss) with say a 10degree slip 
>>> indication variation, given all the other factors that determine climb rate.
>>> 
>>> This might b able to be worked out mathematically given the airflows angle 
>>> on the wing and fuselage drags differences
>>> 
>>> I suspect that are several aerodynamic factors would have to be considered, 
>>> especially given the the thermal core is dynamic.
>>> 
>>> A question for modern designers perhaps, especially when all aviation 
>>> design is a trade off
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Richard Frawley
>>> rjfraw...@gmail.com 
>>> 
>>> We do not inherit the earth from our ancestors, we borrow it from our 
>>> children
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
 On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com 
 > wrote:
 
 At 07:36 AM 1/17/2019, you wrote:
> Perhaps the more important question is how to you tell if one technique 
> is better than another. What is a useful baseline?
 
 
 
 
 Climbing better than the other gliders is the test but what if everybody 
 is using the same less than optimum technique?
 
 Mike
 
 
 
 
 
 
> On 17 Jan 2019, at 7:16 am, Mike Borgelt < 
> mborg...@borgeltinstruments.com > 
> wrote:
> 
>> When circling in a thermal, do you 
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>> 
>> 
>> Your technique may not be doing what you think it is.
>> 
>> Mike
>> 
>> 
>> 
>> 
>> 
>> 
>> Borgelt Instruments - design & manufacture of quality soaring 
>> instrumentation since 1978
>> www.borgeltinstruments.com 
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>> ___
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>> http://lists.base64.com.au/listinfo/aus-soaring 
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>>  
>> http://lists.base64.com.au/listinfo/aus-soaring 
>> 
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 instrumentation since 1978
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Re: [Aus-soaring] slip in thermals?

[Erich Wittstock]

Hello Mike,
is this article useful?
http://www.wisoar.org/Documents/Holighaus%20-%20Thermalling%20Efficiency.pdf
ta
Erich


On Thu, 17 Jan 2019 at 07:16, Mike Borgelt 
wrote:

> When circling in a thermal, do you
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
>
>
> Your technique may not be doing what you think it is.
>
> Mike
>
>
>
>
>
>
> *Borgelt Instruments* -
> *design & manufacture of quality soaring instrumentation since 1978 *
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
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Re: [Aus-soaring] slip in thermals?

[Bob Dircks]

Good points Richard,

However I still find the use of the word "pointing" very ambiguous.

I suggest that "pointing" indicates a direction radiating from the
viewpoint.
This would have us discussing the forward direction of the string,  while
it is more common to consider the rearward direction of the string. ie
it's trailing direction.



On Thu, 17 Jan. 2019, 10:18 am Richard Frawley  the string can be either pointing in to the thermal centre or pointing out
> away from the core
>
> there is some conjecture that with some aircraft (I read that it was
> mainly older pre-1980 craft) that with the string pointing to the outside,
> they may be more efficient in the climb.
>
> There are also some views that say that polyhedral vs straight wings tend
> to set up a balance that has the string pointing out.
>
> I have not yet seen any empiric data or detailed theory that speaks to
> these suppositions, I expect it exists somewhere tho.
>
> More questions and less answers still…..
>
>
>
>
>
>
>
>
> Richard Frawley
> rjfraw...@gmail.com
>
> We do not inherit the earth from our ancestors, we borrow it from our
> children
>
>
>
>
>
>
>
> On 17 Jan 2019, at 10:12 am, Bob Dircks  wrote:
>
> Mike,
> In your original question,
>
> Part b,
>
> By "pointing" I presume you mean "trailing" ?
>
> To me, in this case "pointing" could be the direction of the forward end
> of the string.
>
>
> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt <
> mborg...@borgeltinstruments.com wrote:
>
>> So how about answering the questions?
>>
>>
>> Mike
>>
>> At 08:51 AM 1/17/2019, you wrote:
>>
>> and what is the expected differential (gain/loss) with say a 10degree
>> slip indication variation, given all the other factors that determine climb
>> rate.
>>
>> This might b able to be worked out mathematically given the airflows
>> angle on the wing and fuselage drags differences
>>
>> I suspect that are several aerodynamic factors would have to be
>> considered, especially given the the thermal core is dynamic.
>>
>> A question for modern designers perhaps, especially when all aviation
>> design is a trade off
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Richard Frawley
>> rjfraw...@gmail.com
>>
>> We do not inherit the earth from our ancestors, we borrow it from our
>> children
>>
>>
>>
>>
>>
>>
>>
>> On 17 Jan 2019, at 9:43 am, Mike Borgelt <
>> mborg...@borgeltinstruments.com> wrote:
>>
>> At 07:36 AM 1/17/2019, you wrote:
>>
>> Perhaps the more important question is how to you tell if one technique
>> is better than another. What is a useful baseline?
>>
>>
>>
>>
>>
>> Climbing better than the other gliders is the test but what if everybody
>> is using the same less than optimum technique?
>>
>> Mike
>>
>>
>>
>>
>>
>>
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt <
>> mborg...@borgeltinstruments.com> wrote:
>>
>> When circling in a thermal, do you
>> a) keep the string centered
>> b) fly with it pointing to the outside of the turn
>> c) why?
>>
>>
>> Your technique may not be doing what you think it is.
>>
>> Mike
>>
>>
>>
>>
>>
>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> ___
>> Aus-soaring mailing list
>> Aus-soaring@lists.base64.com.au
>> http://lists.base64.com.au/listinfo/aus-soaring
>>
>> ___ Aus-soaring mailing list
>> Aus-soaring@lists.base64.com.au
>> http://lists.base64.com.au/listinfo/aus-soaring
>>
>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> ___
>> Aus-soaring mailing list
>> Aus-soaring@lists.base64.com.au
>> http://lists.base64.com.au/listinfo/aus-soaring
>>
>>
>> ___ Aus-soaring mailing list
>> Aus-soaring@lists.base64.com.au
>> http://lists.base64.com.au/listinfo/aus-soaring
>>
>> *Borgelt Instruments* -
>> *design & manufacture of quality soaring instrumentation since 1978 *
>> www.borgeltinstruments.com
>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>> mob: 042835 5784 :  int+61-42835 5784
>> P O Box 4607, Toowoomba East, QLD 4350, Australia
>> ___
>> Aus-soaring mailing list
>> Aus-soaring@lists.base64.com.au
>> http://lists.base64.com.au/listinfo/aus-soaring
>>
> ___
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> http://lists.base64.com.au/listinfo/aus-soaring
>
>
> ___
> Aus-soaring mai

Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

the string can be either pointing in to the thermal centre or pointing out away 
from the core

there is some conjecture that with some aircraft (I read that it was mainly 
older pre-1980 craft) that with the string pointing to the outside, they may be 
more efficient in the climb.

There are also some views that say that polyhedral vs straight wings tend to 
set up a balance that has the string pointing out.

I have not yet seen any empiric data or detailed theory that speaks to these 
suppositions, I expect it exists somewhere tho.

More questions and less answers still…..








Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







> On 17 Jan 2019, at 10:12 am, Bob Dircks  wrote:
> 
> Mike,
> In your original question,
> 
> Part b,
> 
> By "pointing" I presume you mean "trailing" ?
> 
> To me, in this case "pointing" could be the direction of the forward end of 
> the string. 
> 
> 
> On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt   wrote:
> So how about answering the questions?
> 
> 
> Mike
> 
> At 08:51 AM 1/17/2019, you wrote:
>> and what is the expected differential (gain/loss) with say a 10degree slip 
>> indication variation, given all the other factors that determine climb rate.
>> 
>> This might b able to be worked out mathematically given the airflows angle 
>> on the wing and fuselage drags differences
>> 
>> I suspect that are several aerodynamic factors would have to be considered, 
>> especially given the the thermal core is dynamic.
>> 
>> A question for modern designers perhaps, especially when all aviation design 
>> is a trade off
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> Richard Frawley
>> rjfraw...@gmail.com 
>> 
>> We do not inherit the earth from our ancestors, we borrow it from our 
>> children
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>>> On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com 
>>> > wrote:
>>> 
>>> At 07:36 AM 1/17/2019, you wrote:
 Perhaps the more important question is how to you tell if one technique is 
 better than another. What is a useful baseline?
>>> 
>>> 
>>> 
>>> 
>>> Climbing better than the other gliders is the test but what if everybody is 
>>> using the same less than optimum technique?
>>> 
>>> Mike
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
 On 17 Jan 2019, at 7:16 am, Mike Borgelt < mborg...@borgeltinstruments.com 
 > wrote:
 
> When circling in a thermal, do you 
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
> 
> 
> Your technique may not be doing what you think it is.
> 
> Mike
> 
> 
> 
> 
> 
> 
> Borgelt Instruments - design & manufacture of quality soaring 
> instrumentation since 1978
> www.borgeltinstruments.com 
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia 
> ___
> Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au 
> http://lists.base64.com.au/listinfo/aus-soaring 
> ___
>  Aus-soaring mailing list Aus-soaring@lists.base64.com.au 
>  
> http://lists.base64.com.au/listinfo/aus-soaring 
> 
>>> Borgelt Instruments - design & manufacture of quality soaring 
>>> instrumentation since 1978
>>> www.borgeltinstruments.com 
>>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>>> mob: 042835 5784 :  int+61-42835 5784
>>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>>> ___
>>> Aus-soaring mailing list
>>> Aus-soaring@lists.base64.com.au 
>>> http://lists.base64.com.au/listinfo/aus-soaring 
>>> 
>> ___ Aus-soaring mailing list 
>> Aus-soaring@lists.base64.com.au  
>> http://lists.base64.com.au/listinfo/aus-soaring 
>> Borgelt Instruments - 
>> design & manufacture of quality soaring instrumentation since 1978
> www.borgeltinstruments.com
>  tel:   07 4635 5784 overseas: 
> int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> 
> ___
> Aus-soaring mailing list
> A

Re: [Aus-soaring] slip in thermals?

[Bob Dircks]

Mike,
In your original question,

Part b,

By "pointing" I presume you mean "trailing" ?

To me, in this case "pointing" could be the direction of the forward end of
the string.


On Thu, 17 Jan. 2019, 9:54 am Mike Borgelt  So how about answering the questions?
>
>
> Mike
>
> At 08:51 AM 1/17/2019, you wrote:
>
> and what is the expected differential (gain/loss) with say a 10degree slip
> indication variation, given all the other factors that determine climb rate.
>
> This might b able to be worked out mathematically given the airflows angle
> on the wing and fuselage drags differences
>
> I suspect that are several aerodynamic factors would have to be
> considered, especially given the the thermal core is dynamic.
>
> A question for modern designers perhaps, especially when all aviation
> design is a trade off
>
>
>
>
>
>
>
>
>
>
> Richard Frawley
> rjfraw...@gmail.com
>
> We do not inherit the earth from our ancestors, we borrow it from our
> children
>
>
>
>
>
>
>
> On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com>
> wrote:
>
> At 07:36 AM 1/17/2019, you wrote:
>
> Perhaps the more important question is how to you tell if one technique is
> better than another. What is a useful baseline?
>
>
>
>
>
> Climbing better than the other gliders is the test but what if everybody
> is using the same less than optimum technique?
>
> Mike
>
>
>
>
>
>
> On 17 Jan 2019, at 7:16 am, Mike Borgelt < mborg...@borgeltinstruments.com>
> wrote:
>
> When circling in a thermal, do you
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
>
>
> Your technique may not be doing what you think it is.
>
> Mike
>
>
>
>
>
>
> *Borgelt Instruments* -
> *design & manufacture of quality soaring instrumentation since 1978 *
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> ___
> Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au
> http://lists.base64.com.au/listinfo/aus-soaring
>
> ___ Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au
> http://lists.base64.com.au/listinfo/aus-soaring
>
>
> *Borgelt Instruments* -
> *design & manufacture of quality soaring instrumentation since 1978 *
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> ___
> Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au
> http://lists.base64.com.au/listinfo/aus-soaring
>
>
> ___ Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au
> http://lists.base64.com.au/listinfo/aus-soaring
>
> *Borgelt Instruments* -
> *design & manufacture of quality soaring instrumentation since 1978 *
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> ___
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> http://lists.base64.com.au/listinfo/aus-soaring
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

damed if I know, but what I do know its good to ask a of of questions

It common for the layman to want simple answers for complex issues which can 
lead to doing an ineffective thing,

In this case having the string in the centre or a few degrees to the outside, 
it may in the overall scheme of things make not discernible difference

For example if the glider settles and it easier to maintain a steady climb with 
a few degrees of offset yaw, it might be less drag than futzing with the 
controls (creating more drag) to keep in the centre. Additionally putting focus 
on the string means that the pilots mental focus is not on something else (like 
staying in the core or not adjusting to being blown out by horizontal gusts), 
hence there is always tradeoff. If there is gain, it might be so small as to 
not warrant the attention tax.





Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







> On 17 Jan 2019, at 9:54 am, Mike Borgelt  
> wrote:
> 
> So how about answering the questions?
> 
> 
> Mike
> 
> At 08:51 AM 1/17/2019, you wrote:
>> and what is the expected differential (gain/loss) with say a 10degree slip 
>> indication variation, given all the other factors that determine climb rate.
>> 
>> This might b able to be worked out mathematically given the airflows angle 
>> on the wing and fuselage drags differences
>> 
>> I suspect that are several aerodynamic factors would have to be considered, 
>> especially given the the thermal core is dynamic.
>> 
>> A question for modern designers perhaps, especially when all aviation design 
>> is a trade off
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> Richard Frawley
>> rjfraw...@gmail.com 
>> 
>> We do not inherit the earth from our ancestors, we borrow it from our 
>> children
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>>> On 17 Jan 2019, at 9:43 am, Mike Borgelt < mborg...@borgeltinstruments.com 
>>> > wrote:
>>> 
>>> At 07:36 AM 1/17/2019, you wrote:
 Perhaps the more important question is how to you tell if one technique is 
 better than another. What is a useful baseline?
>>> 
>>> 
>>> 
>>> 
>>> Climbing better than the other gliders is the test but what if everybody is 
>>> using the same less than optimum technique?
>>> 
>>> Mike
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
 On 17 Jan 2019, at 7:16 am, Mike Borgelt < mborg...@borgeltinstruments.com 
 > wrote:
 
> When circling in a thermal, do you 
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
> 
> 
> Your technique may not be doing what you think it is.
> 
> Mike
> 
> 
> 
> 
> 
> 
> Borgelt Instruments - design & manufacture of quality soaring 
> instrumentation since 1978
> www.borgeltinstruments.com 
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia 
> ___
> Aus-soaring mailing list
> Aus-soaring@lists.base64.com.au 
> http://lists.base64.com.au/listinfo/aus-soaring 
> ___
>  Aus-soaring mailing list Aus-soaring@lists.base64.com.au 
>  
> http://lists.base64.com.au/listinfo/aus-soaring 
> 
>>> Borgelt Instruments - design & manufacture of quality soaring 
>>> instrumentation since 1978
>>> www.borgeltinstruments.com 
>>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>>> mob: 042835 5784 :  int+61-42835 5784
>>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>>> ___
>>> Aus-soaring mailing list
>>> Aus-soaring@lists.base64.com.au 
>>> http://lists.base64.com.au/listinfo/aus-soaring 
>>> 
>> ___ Aus-soaring mailing list 
>> Aus-soaring@lists.base64.com.au 
>> http://lists.base64.com.au/listinfo/aus-soaring 
>> Borgelt Instruments - 
>> design & manufacture of quality soaring instrumentation since 1978
> www.borgeltinstruments.com
>  tel:   07 4635 5784 overseas: 
> int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> 
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

So how about answering the questions?


Mike

At 08:51 AM 1/17/2019, you wrote:
and what is the expected differential (gain/loss) with say a 
10degree slip indication variation, given all the other factors that 
determine climb rate.


This might b able to be worked out mathematically given the airflows 
angle on the wing and fuselage drags differences


I suspect that are several aerodynamic factors would have to be 
considered, especially given the the thermal core is dynamic.


A question for modern designers perhaps, especially when all 
aviation design is a trade off











Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







On 17 Jan 2019, at 9:43 am, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:


At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how to you tell if one 
technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the test but what if 
everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
< 
mborg...@borgeltinstruments.com> wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of quality soaring 
instrumentation since 1978

www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784:  int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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instrumentation since 1978

www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

and what is the expected differential (gain/loss) with say a 10degree slip 
indication variation, given all the other factors that determine climb rate.

This might b able to be worked out mathematically given the airflows angle on 
the wing and fuselage drags differences

I suspect that are several aerodynamic factors would have to be considered, 
especially given the the thermal core is dynamic.

A question for modern designers perhaps, especially when all aviation design is 
a trade off










Richard Frawley
rjfraw...@gmail.com

We do not inherit the earth from our ancestors, we borrow it from our children







> On 17 Jan 2019, at 9:43 am, Mike Borgelt  
> wrote:
> 
> At 07:36 AM 1/17/2019, you wrote:
>> Perhaps the more important question is how to you tell if one technique is 
>> better than another. What is a useful baseline?
> 
> 
> 
> 
> Climbing better than the other gliders is the test but what if everybody is 
> using the same less than optimum technique?
> 
> Mike
> 
> 
> 
> 
> 
> 
>> On 17 Jan 2019, at 7:16 am, Mike Borgelt < mborg...@borgeltinstruments.com 
>> > wrote:
>> 
>>> When circling in a thermal, do you 
>>> a) keep the string centered
>>> b) fly with it pointing to the outside of the turn
>>> c) why?
>>> 
>>> 
>>> Your technique may not be doing what you think it is.
>>> 
>>> Mike
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Borgelt Instruments - design & manufacture of quality soaring 
>>> instrumentation since 1978
>>> www.borgeltinstruments.com 
>>> tel:   07 4635 5784 overseas: int+61-7-4635 5784
>>> mob: 042835 5784 :  int+61-42835 5784
>>> P O Box 4607, Toowoomba East, QLD 4350, Australia 
>>> ___
>>> Aus-soaring mailing list
>>> Aus-soaring@lists.base64.com.au 
>>> http://lists.base64.com.au/listinfo/aus-soaring 
>>> ___
>>>  Aus-soaring mailing list Aus-soaring@lists.base64.com.au 
>>> http://lists.base64.com.au/listinfo/aus-soaring 
>>> Borgelt Instruments - 
>>> design & manufacture of quality soaring instrumentation since 1978
> www.borgeltinstruments.com
>  tel:   07 4635 5784 overseas: 
> int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia
> 
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

At 07:36 AM 1/17/2019, you wrote:
Perhaps the more important question is how to you tell if one 
technique is better than another. What is a useful baseline?





Climbing better than the other gliders is the test but what if 
everybody is using the same less than optimum technique?


Mike






On 17 Jan 2019, at 7:16 am, Mike Borgelt 
<mborg...@borgeltinstruments.com> 
wrote:



When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike






Borgelt Instruments - design & manufacture of quality soaring 
instrumentation since 1978

www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784:  int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
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Re: [Aus-soaring] slip in thermals?

[Richard Frawley]

Perhaps the more important question is how to you tell if one technique is 
better than another. What is a useful baseline?



> On 17 Jan 2019, at 7:16 am, Mike Borgelt  
> wrote:
> 
> When circling in a thermal, do you 
> a) keep the string centered
> b) fly with it pointing to the outside of the turn
> c) why?
> 
> 
> Your technique may not be doing what you think it is.
> 
> Mike
> 
> 
> 
> 
> 
> 
> Borgelt Instruments - design & manufacture of quality soaring instrumentation 
> since 1978
> www.borgeltinstruments.com
> tel:   07 4635 5784 overseas: int+61-7-4635 5784
> mob: 042835 5784 :  int+61-42835 5784
> P O Box 4607, Toowoomba East, QLD 4350, Australia   
> 
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Re: [Aus-soaring] slip in thermals?

[Mike Borgelt]

When circling in a thermal, do you
a) keep the string centered
b) fly with it pointing to the outside of the turn
c) why?


Your technique may not be doing what you think it is.

Mike







Borgelt Instruments - design & manufacture of quality soaring 
instrumentation since 1978

www.borgeltinstruments.com
tel:   07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784:  int+61-42835 5784
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