RE: [DOG mailing list] Spins

[Ian Williams]

Hi All,

 It is interesting following the threads.  

I guess I am a little biased but after around 46 years of being involved with 
small aircraft and around 45 years of towing gliders in all types of 
interesting aeroplanes plus a lot of GA aircraft, I recon the little Dimona has 
them all beaten.  It has a few downsides but it has to be one of the most 
enjoyable aircraft I have owned and operated.  

There is some resentment from the purists within the NZ gliding movement who 
consider that anything with less performance than a duo discus is not really a 
glider and anything with an engine even worse. However I guess that is a common 
perception.  A bit like a yachtie with an engine.

However the ability to carry out long cross countries, able to soar in strong 
conditions … able to get there in the first place, operate with no drama 
regarding tow planes, winches etc … all just great.

However while it may not be a big issue, I did have a small issue the other day 
which I think is worth passing on.   I was demonstrating the Dimona to a 
gliding group north of Auckland and was operating off a sealed strip. There was 
a crosswind of about 8 kts. 

With the main wheels significantly forward of the C of G, the steering response 
from the tailwheel  on take off is excellent.  However once the tailwheel  
lifts, the sudden increase in rudder input to keep straight can catch you 
unawares. That combined with the sudden increase in elevator effect at around 
the same time (being a T tail) does mean a significant change in the control 
effect which pilots need to be aware of..  Probably not a big issue but as 
we normally operate from a grass strip where any issues such as that are not so 
apparent.

 

Best regards

 

Ian Williams

New Zealand

 

From: dog@lists.riverland.net.au [mailto:dog@lists.riverland.net.au] 
Sent: Tuesday, 28 June 2016 12:18 p.m.
To: dog@lists.riverland.net.au
Subject: Re: [DOG mailing list] Spins

 

Hi All,

I've been reading this thread with interest.

In Oz we are required to undergo annual spin checks as part of the Annual 
Flight Review.

For a club like ours only operating the Dimona its inconvenient to have to 
arrange for access to a conventional glider approved for spinning for our 
members through another club.

 

The upside is that we get to fly aerotow again and remain reasonably current 
when we probably wouldn't bother otherwise and also we get reminded of what 
gliding is all about. Not that gliding engine off isn't the major component of 
nearly all of our flights including landings, but a reminder of what modern 
gliders are actually capable of.

Over the last couple of years our AFRs have been in a beautiful example of an 
IS28 just a couple of days before its 30 year retirement (yes not modern but 
still a better glider than the H36) and in a DG1000.

 

I have to say though that other than the pilot being checked demonstrating 
their recognition of fairly generic spin onset symptoms and then the standard 
recovery technique, I'm not so sure about how much value there is for us in 
spinning a DG1000.

It would be far better to be assessed in spin entry and recovery in our Dimona.

I assume that this would be the case for almost all Dimona operators in this 
country at least.

 

Spin checking here involves the three stages of spin prevention, incipient spin 
recovery and full spin recovery. I regularly investigate incipient spin 
recovery in GYT and as Nigel says the aircraft's behavior is quite benign, 
however this has been mainly engine off.

 

I have attached a link to GFA (Gliding Federation of Australia) Operations 
Advice Notice 02/2012 Annual Flight Reviews.

Here is an extract from the section on spinning...

 

For private owners, it is entirely appropriate to take a look at their glider's 
Flight Manual and discuss the stall / spin characteristics of their machine. 
Many high performance gliders are not certified for intentional spinning but 
this does not mean they won't spin! The limitation is usually a consequence of 
the likelihood of exceeding the glider's VNE in the spin recovery should you 
get in one. This just wouldn't apply to the H36.

 

Can the engineers advise of whether there is any value in exploring the 
background for the limitation being imposed and investigating the possibility 
of the restriction being lifted? I guess this is what Kristin would have in 
mind.

 

As an aside Kristin, and with no disrespect intended for the skills of your 
aerobatic friend whatsover, there have been many instances of experienced power 
aerobatic pilots getting into major strife trying our their aerobatic skills in 
gliders. Not so long ago here a highly experienced military fighter pilot 
attempted a rolling maneuver with near catastrophic consequences. As with the 
prowess of highly experienced power pilots (especial CPLs) often not readily 
transferring to gliding without considerable conversion training, aerobatics 
can be the same

Re: [DOG mailing list] Spins

[kristinnowell]

Thanks very much for your help, guys.  Nige, the aero restrictions on SB 12 
came in earlier (Jan 1985).  The wing failure from a July 1986 accident in 
Germany indeed was the result of acc to the investigation  high g loading - at 
high angles of attack.  Wolf Hoffmann further said to Tom awhile back 
commenting on this that the LBA wanted them to “do something” even if no 
structural imperfection was found, thus the SB 19 winglatch kit.  We got the 
original accident summary from the BFU database, it doesn't say much, but it 
does say this:


Accident in Walchensee on 29.07.1986

Aircraft wing related event (ATA Code:5700) , during Cruise. {Occurrence}
Fuselage main bulkheads (ATA Code:5312)
Wing attachment fitting (ATA Code:5740)


Weather conditions VMC

Aircraft SN 36115  D-KESL

Aircraft total time 820 Hours *flying club

crew experience This Aircraft type 17 Hour(s)
All types 1198 Hour(s)


Events: primary break of the right wing in the flight (SE) - cruising (D1) |_ 
FUSELAGE/BULKHEADS (70BA) |_ Not
sufficiently firm/solid (88H4) |_ WINGS/WING ATTACHMENT FITTINGS, BOLTS (70AC) 
|_ Not sufficiently firm/solid
(88H4)







Sent from Windows Mail





From: ni...@limbachaustralia.com
Sent: ‎Saturday‎, ‎June‎ ‎25‎, ‎2016 ‎10‎:‎41‎ ‎AM
To: dog@lists.riverland.net.au







Yep. I have had it go in unintentionally a couple of times while soaring in 
thermal conditions. A good gust brought it on both times. It is quite benign 
and relaxing back stick is enough to get a quick recovery from the start of an 
incipient. I have deliberately done it once to see what it is like although 
didn’t let it fully develop. Again I would describe it as a bit benign. Easy 
recovery and no noticeable hesitation. I did it intentionally with 1 up but the 
other 2 times were 2 up. All 3 times were at about half fuel load. It isn’t 
what I would say as prone to spinning IE doesn’t drop in at the drop of a hat.

Hope that is of help.

I thought the Aero  restrictions came in after the catastrophic wing failure 
from Gross Overload during Aero’s and thus SB19.

Cheers.

Nige.

 



 


From: Kristin Nowell 

Sent: Saturday, June 25, 2016 10:30 AM

To: dog@lists.riverland.net.au 

Subject: [DOG mailing list] Spins

 
 


Hi all,

Our glider aerobat friend (Unlimited!) is coming to Maine for vacation, and is 
keen to fly in Tom's Dimona. Has anyone ever (unintentionally) spun it? 
Originally it was certified for aerobatics but then came 1985 SB 12 ( "Due to 
irregularities observed at spinning, further tests will be performed and until 
then the placard must be installed), like what kind of irregularities? And 
either the tests were not done or not satisfactory as this operating 
restriction was never lifted, unlike those of service bulletin 18 ("glider 
flying prohibited!" "dual controlled instruction flights only"!), which were 
removed upon install of the wing latch kit (SB 19).

Thanks Kristin

Re: [DOG mailing list] Spins

[Nigel Baker]

Yep. I have had it go in unintentionally a couple of times while soaring in 
thermal conditions. A good gust brought it on both times. It is quite benign 
and relaxing back stick is enough to get a quick recovery from the start of an 
incipient. I have deliberately done it once to see what it is like although 
didn’t let it fully develop. Again I would describe it as a bit benign. Easy 
recovery and no noticeable hesitation. I did it intentionally with 1 up but the 
other 2 times were 2 up. All 3 times were at about half fuel load. It isn’t 
what I would say as prone to spinning IE doesn’t drop in at the drop of a hat.
Hope that is of help.
I thought the Aero  restrictions came in after the catastrophic wing failure 
from Gross Overload during Aero’s and thus SB19.
Cheers.
Nige.


From: Kristin Nowell 
Sent: Saturday, June 25, 2016 10:30 AM
To: dog@lists.riverland.net.au 
Subject: [DOG mailing list] Spins

Hi all,

Our glider aerobat friend (Unlimited!) is coming to Maine for vacation, and is 
keen to fly in Tom's Dimona. Has anyone ever (unintentionally) spun it? 
Originally it was certified for aerobatics but then came 1985 SB 12 ( "Due to 
irregularities observed at spinning, further tests will be performed and until 
then the placard must be installed), like what kind of irregularities? And 
either the tests were not done or not satisfactory as this operating 
restriction was never lifted, unlike those of service bulletin 18 ("glider 
flying prohibited!" "dual controlled instruction flights only"!), which were 
removed upon install of the wing latch kit (SB 19).

Thanks Kristin 

Re: [DOG mailing list] Spins

[Ian Williams]

I think the Wing profile is the same as used on the old Cirrus gliders.  ..  
Not high speed but very stable at the slow speed end. (Which probably explains 
why most of the ex Thai Dimona's still exist).  If yours has the older aileron 
control don't panic if you see the ailerons lift   An inch or so above 100kts. 

Sent from my iPhone

> On 25/06/2016, at 13:00, Kristin Nowell  wrote:
> 
> Hi all,
> 
> Our glider aerobat friend (Unlimited!) is coming to Maine for vacation, and 
> is keen to fly in Tom's Dimona. Has anyone ever (unintentionally) spun it? 
> Originally it was certified for aerobatics but then came 1985 SB 12 ( "Due to 
> irregularities observed at spinning, further tests will be performed and 
> until then the placard must be installed), like what kind of 
> irregularities? And either the tests were not done or not satisfactory as 
> this operating restriction was never lifted, unlike those of service bulletin 
> 18 ("glider flying prohibited!" "dual controlled instruction flights only"!), 
> which were removed upon install of the wing latch kit (SB 19).
> 
> Thanks Kristin

Re: [DOG mailing list] Spins

[Ian Williams]

Shouldn't mention it but ours spins well and comes out within half a turn.
Has to be really aggravated power off but full
Power fine pitch it drops into a spin much easier 
In New Zealand it is mandatory to spin at every 2 yearly flight review.   But 
is usually done in a club 2 seater not a Dimona of course.  

Sent from my iPhone

> On 25/06/2016, at 13:00, Kristin Nowell  wrote:
> 
> Hi all,
> 
> Our glider aerobat friend (Unlimited!) is coming to Maine for vacation, and 
> is keen to fly in Tom's Dimona. Has anyone ever (unintentionally) spun it? 
> Originally it was certified for aerobatics but then came 1985 SB 12 ( "Due to 
> irregularities observed at spinning, further tests will be performed and 
> until then the placard must be installed), like what kind of 
> irregularities? And either the tests were not done or not satisfactory as 
> this operating restriction was never lifted, unlike those of service bulletin 
> 18 ("glider flying prohibited!" "dual controlled instruction flights only"!), 
> which were removed upon install of the wing latch kit (SB 19).
> 
> Thanks Kristin