Odd Airfoil

[Ken Culbertson]

I found this airfoil on a three view of one of the European F2B planes but I cannot remember where I saw it.  I built a stab using it for Endgame IV but it is not too late since I have not mounted it yet. I used something similar on Endgame III with a much thicker elevator LE and it flies great.  It appears to be designed for corners with a significant dead zone around neutral.  I do not grasp the significance of the rounded stab TE leading into the flap recess.  The one I built is flatter at that point.  Has anybody seen this before?  I am very open to suggestions.

Ken

[Air Ministry .]

Think its pretty much the same theory as ' taped hinges ' . A ten foot gap ( as it were ) and the air bleeds through . PRESSURE .

wereas ' sealed ' it acts ' of a piece ' , rather than two joined /
Think it was a Dutch bloke , picture of ' hinge ' in Aeromodeler Mag. with paper or cloth in the gap , to illustrate the closeness off fit .
So , seeing the picture , every man & his dog tried it . a few Germans & Italians anyway .

Other Thing is the surface continuity , when the elevators deflected . The hope is that the air stays glued on .
Traditional ' sewn ' hinges , with radius , the elevator ' rolls ' on the stab. Similar effect . But impossable to calculate true center of deflection, perhaps .

[Ken Culbertson]

A little more investigating and I remember where I saw it.  It is a imbedded version of Igor's MaxBee.  Still want to know something about it.

Ken

[Brett Buck]

A little more investigating and I remember where I saw it.  It is a imbedded version of Igor's MaxBee.  Still want to know something about it.

Ken

  I am not sure what the question about it might be. If you took a solid airfoil, and decided to hinge it at the 40% mark, that's about what you would wind up with. It's a common full-scale practice, and most of the similar attempts at model implementations look about the same. If you later decide to make the elevator smaller than the stab, you have what you show.

    It doesn't prevent air flow through the gap like a seal. But it does greatly reduce the discontinuity you would otherwise have with a right-angle trailing edge and a wedge on the LE, which is a huge divot even when not deflected and a massive divot when it is deflected.

    Brett

[Ken Culbertson]

  I am not sure what the question about it might be. If you took a solid airfoil, and decided to hinge it at the 40% mark, that's about what you would wind up with. It's a common full-scale practice, and most of the similar attempts at model implementations look about the same. If you later decide to make the elevator smaller than the stab, you have what you show.

    It doesn't prevent air flow through the gap like a seal. But it does greatly reduce the discontinuity you would otherwise have with a right-angle trailing edge and a wedge on the LE, which is a huge divot even when not deflected and a massive divot when it is deflected.

    Brett

Thank you.  The only difference would be imbedding the elevator 1/8" into the stab.  I have been doing that for years on my stabs without sealing them.  When I watch Matt's WC plane corner effortlessly, I wonder if it is worth the effort when you can achieve nearly the same results with conventional construction.  Probably not but it is a hobby after all.

ken

[Air Ministry .]

Wotcher wanna DO , is make it PRECISION . either rout a half circle groove in a board & glue in oor holden sandpaper . For the L E , and
use a TUBE with ditto , or a dowel , not a cheap one . So as theyre ' enginered ' for a precise gap .

Cunning Swine use pre chamfered / wedged edge PLY along the stab. T E , top'n'bottom  . as its stiff . or alloy . or carbon , being in the 22nd century ? .
Got to see That dosnt dig into the surfaces of the elevator , etc .This assumes you throw the hinge wire in  af ter everything else etc .

YOU can see , deflected - theres not a bump or a gap . Hopefully . Which seems to be the main point of it all . I cant see much ' bleed through ' of pressure ,
as if it were ' FLOW ' it'd be going aft , up'n' fwd. - around - and sucked out where iot'be blown in . or if its up & topside , it'd be near sealed at full deflection .

So it might get you tighter cleaner more controlled coners . and hopefully stop BOUNCE / Bobble on exits ? ? . being more efficent .less variable pressure fluctuation  , and so forth .

[Air Ministry .]

It'd give you a advantage of the built up leading edge as a stiffer structural member too . If you rolled / moulded say a 1/16 sheet front . Bit like this . You can see aft its rather lightweight .


Wether some turkey had walked on the tailplane , top aft . One was a pig , with uncontrolability occuring nose down full wellie way before achiveing the potential speed  .
Eventually they found the rear of the stab skin was depressed / concave spanwise , with the rear area / edge incliened .outward. divergent . Whacking it back flat cured it .

The Moral being ya want accurate airfoil , not wobbly or irregular at the transition Stab to Elevator . Or anywhere else for that matter . The differance being top line to also ran .

They dont seem to worried about air feeding through here , maybe someones got some figures / data , on it . Though SEALING is considered de rigueur on top line F2B



As the STAB. rear is just box & edge ,

The interface or THAT EDGE & the Elevator L E may be the more crucial consideration ? .

Itresting its no flat at all . asin ALL tapered X - section .

[fred cesquim]

have used on several scale models and the Nemesis F2B. extra worth and no noticieable gain over traditional method. if properly done no need to seal inexistent gap.
looks absolutely good anyway