Oh yes inddeedy, they have a very interesting way of communicating. Fast?
I'm not too sure of that.
Ian P
----- Original Message -----
From: "JR" <[EMAIL PROTECTED]>
To: "Discussion of issues relating to Soaring in Australia."
<[email protected]>
Sent: Tuesday, June 20, 2006 6:15 PM
Subject: Re: [Aus-soaring] Bent up wing outer panels
Ian,
I spoke to the worlds fastest Indian on the phone last night, he was
trying
to convert me to another phone company
regards JR
----- Original Message -----
From: "Patching" <[EMAIL PROTECTED]>
To: "Discussion of issues relating to Soaring in Australia."
<[email protected]>
Sent: Tuesday, June 20, 2006 1:10 PM
Subject: Re: [Aus-soaring] Bent up wing outer panels
Hey caleb,
the kookas' all have a decided wing kink as well. Just goes to proove
the
everything stays the same, it just gets refined a little.
See ya, I'm off to see the Worlds Fastest Indian.
IP
KPST
----- Original Message -----
From: "Caleb White" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, June 20, 2006 1:01 PM
Subject: Re: [Aus-soaring] Bent up wing outer panels
> Hi Folks,
>
> I think this discussion needs some clarification as to what is referred
to
> as a ‘kink’. Are we referring the stepped taper (when viewed in plan
form
> from above) as the ‘kinks’? In which case we are discussing the desire
to
> achieve an elliptical plan form (with the intent of achieving an
> elliptical lift distribution) OR Are we discussing the stepped changes
in
> dihedral in which case we are talking about achieving elliptical
dihedral?
>
> As with all aircraft design the design of sailplane wings is a
compromise.
> What is desirable is balanced with what is affordable to manufacture. A
> stepped planform and dihedral is an excellent example of ‘optimised
> compromise’.
>
> Cheers,
>
> Caleb
>
> Kookaburra Precision Soaring Team
>
>
> -----Original Message-----
> From: Mike Borgelt <[EMAIL PROTECTED]>
> To: "Discussion of issues relating to Soaring in Australia."
> <[email protected]>
> Date: Tue, 20 Jun 2006 12:46:06 +1000
> Subject: Re: [Aus-soaring] Bent up wing outer panels
>
> At 11:57 AM 20/06/2006, you wrote:
>>Dear All (Bernard E would read this as 'space' but I'll stay with the
>>English)
>>
>>There is the limitation in two dimensional aerodynamics of a minimum
>>in the induced drag coefficient of:
>>
>> Cd (induced) = Cl squared divided by (Pi X Aspect
>> ratio). (Apologies, I haven't the time to write it out clearer.)
>>
>>So with an ideal lift distribution along the two dimensional wing
>>planform, that is the lowest you can get the induced drag
>>coefficient down to. Induced drag relates to drag due to wing tip
>>vortices (actually more complicated than just tip vortices but let
>>us leave that for now).
>>
>>I think somewhere I have in my overloaded filing cabinets an article
>>from a learned aerospace journal which deals with induced drag for
>>wings operating in three dimensions. My recollection (unchecked
>>because the article is somewhere misplaced) was that when the wing
>>was considered to operate in three dimensions, and computing power
>>was brought to bear on the calculations, a slender wing with the
>>outer sections bending upwards and backwards could achieve an
>>induced drag coefficient BELOW the minimum as determined from two
>>dimensional aerodynamics.
>>
>>I remember when the Nimbus 4 first came out and there was a photo of
>>the 25 m wings bending significantly upwards during steep
>>thermalling turning. So we have with our sailplanes with higher
>>aspect ratios and more slender spars wings which are operating in
>>three dimensions.
>>
>>So I do not think that wing kinks in the outer wing panels are a
>>fashion statement or a marketing ploy, but rather founded on serious
>>efforts to reduce drag.
>>
>>Beyond that I leave it to some far more knowledgeable person on wing
>>aerodynamics to provide futher illumination on the matter.
>>
>>Cheers
>>
>>Roger Druce
>>
>><mailto:[EMAIL PROTECTED]>[EMAIL PROTECTED]
>>
>>
>
> Roger,
>
> I think I have the same article by the late R.T.Jones of NACA and
> later NASA reknown. I guess the issue is - does the discontinuity at
> the kink increase the profile drag more than the 3D nature of the
> bent wing decreases it.
>
> The tendency at a kink is for the leading edge discontinuity to trip
> flow to turbulent and for the airfoil to stall earlier although it
> would seem you would need a fairly marked kink for this to occur.
> Allegedly this is what happened on the F4U Corsair(the earlier stall
> in the kink.
>
> Mike
> Borgelt Instruments - manufacturers of quality soaring instruments
> phone Int'l + 61 746 355784
> fax Int'l + 61 746 358796
> cellphone Int'l + 61 428 355784
> Int'l + 61 429 355784
> email: [EMAIL PROTECTED]
> website: www.borgeltinstruments.com
>
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