Scratch built 66” Alula using HD Thermocol, my entry for Sweepstakes

Started by ashJR7202, March 17, 2014, 06:53:55 PM

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K K Iyer

"No one would want to use a semi symmetrical airfoli as a vertical stab."

I'm using one!

SunLikeStar

A little more detail please. Can you please explain why are you using a semi symmetrical airfoli on a vertical stabilizer? We are talking about a performance glider here. Which kind of model are you using this on?  I hope you are not talking about a control line model. A picture would be really helpful. Can you help me with the other questions in my earlier post.

K K Iyer

@sunlikestar
Posted in a lighter vein, as i saw your post just when i was sanding asymmetry into a fin. (FF HLG)
But you are right. Doubt if any aircraft had asymmetrical aerofoil fin. Not even BV 141B.
On models i doubt if there is any gain over a flat plate fin. After all we are flying flat plate wings...

Edit: apologies for diverting a lovely thread.

rcpilotacro

(a) Asymmetrical vertical fins are used to counter torque and propwash in larger Prop & TurboProp aeroplanes (Apart from the fact that these fins are cantered too). Changing the thrust line caters to one one set of power and configuration, outside this changes thrust line aeroplane will behave differently, in model aeroplane it is fine, however in real life aeroplane, asymmetrical & a cantered fin is preferred as it adjusts to the propwash and forward speed (Not to say that it doesn't have a skewed thrust line, it does)

(b) About Flatplate aerodynamics, read my earlier posts on the subject, suffice to say

  (1) Unlike cambered aerofoil where the centre of pressure moves with the angle of attack, in flatplate the centre of pressure does not move,

  (2) Flatplate has much more predictable rise of lift, and the lift rise is linear until stall

  (3) Stall is abrubt though, which means at high angles of slip (Like in a low speed Knife Edge), if the fin stalls, she will imdtly spiral into ground

 (4) there is a factor called MCdr or critical drag rise mach number, for flatplate it is high however super sonic drag is lowest of them all. for which reason it is used in most missiles


so much for assymetrical fin and flatplate aerodynamics
Gusty's Hangar and Introduction.

A Good pilot will practice until he gets it right,
A Great pilot will practice until he can't get it wrong.

SunLikeStar

Very interesting! Now I know why my coro mig was not able to do knife edge properly.

@K K Iyer All the best for the glider. I'm also planning to build a 1 meter HLG :thumbsup:

@Ash, for starter I think just go with a flat fin with rounded edges. Do bring the wing core with you if you are coming to the field tomorrow.

rcrcnitesh

Awesome wing seeing others builds I can't stop the keeda inside me for building so after my exams which are ending at 26 of this month are over some thing is coming out for sure.
What software are you using for creating the airfoil templates. Can I use gimp for this purpose.
Maker | Aeromodeller | Teenager

ashJR7202

Wing tips, to give wing proper shape
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
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JR XP7202| DX7

ashJR7202

with wings
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
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ashJR7202

servo slots, and Aluminum 10mm U channel as spar
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

Cut out control surface so that later on can put it using hinges.

being 66" WS, wanted to make it 2 pieces wing for ease carrying it. but at the same time wanted dehydral of around 4-5 dgr. so there was challenge and making detachable as well as dehydral.....
Since had 8mm solid CF rod as joiner, was searching for 8 mm inner dia, CF tube so that can make proper arrangement. but could not find. so decided to make 8 mm ID tube out of newspaper.
Mixed 2 portion water and one portion fevicol and rolled newspaper over CF rod while applying fevicol water using brush. before doing this i applied few drops of oil over CF rod so that paper should not stick to rod. after rolling paper on rod, i let it dry for few hrs and slip out rood from news paper, as u can see u get perfect tube hard enough.
then stick this new paper tube to Aluminum U channel while giving slight angle, used little balsa for support.
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

spar and tube
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

cut slot in the wing to push complete assembly inside and stick it
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

buzz_rc


K K Iyer


arun.sreelakam

Turnigy i10|Flysky 9xb|Hoverfly quadcopter|Arduflyer apm 2.5 with gps|Pixhawk|Homemade micro night vapour|Homemade ornithopter(in progress)| Reptile Quad with Gopro Brushless gimbal | Naza v2| APM 2.6 with GPS | Micro quad self made | FrSky| v911 Helis | 1200mm Hexacopter with 5d gimbal | 1300mm x8 With Red Gimbal | 1000mm Octo|

manojswizera

Russ-40 Trainer, Mr.moss, Pushler, Skysurfer, Mugi , F-22, Red swan, Xtra-300, redfury, flying mantaray.

ashJR7202

Thanks guys!!! finally put spar and same arrangement to other wing as well, now both wings are ready, hav dehydral and detachable.
also fixed servos...now preparing to cover these wings with newspaper and fevicol!!!
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

Spar installed...
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

Paper Wrapping....
Last yr i built Plank wing, CHINOOK-2, you can see its fuse in these pictures, it is made up of core...for test flight i am planning to use that fuse...
and after successful maiden will make new fuse for this bird...control surface are yet to be attached
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

ashJR7202

few more..with dehydral.....
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

K K Iyer

@ashjr7202
Looking very nice.
Why do the wings look droopy (anhedral) in some of the pics?

sundaram


ashJR7202

@KK, that might be bcoz underneath, I stick Nargis Fakiri!!!!!!! just kidding..... after applying paper, i checked wing regularly till it is dry....it is straight, and have around 5-7 dgr of dehydral at center/joint.... may be bcoz of weight it must be dropping at tips....will check it!!!

@Sundaram: thanks for suggestion!!! i have few acrylic spray cans will try it!!!!!
Hanger: Mini Yak-54| 210 Phantom | SU-47| F-15| EuroFighter|Scrappy|SU 27|Eurofighter|Sukhoi PAK FA
Blade MCX| Blade CP PRO
JR XP7202| DX7

shobhit17

swept farward wings do look "droopy"... do not worry Ash.... keep going full steem ahead.....
Happy and safe flying
Shobhit
Well I been into aeromodelling since I was in School....  and then been in the air for over 30 years.  Now looking to be back into aeromodelling full time...

K K Iyer