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Old Jul 02, 2010, 07:36 AM
Watts Up?
jet-ster's Avatar
USA, TX, Arlington
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Very good stuff! I can't wait to see how it works on this jet. Thanks for explaining it for me.

Danny
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Old Jul 02, 2010, 09:03 AM
Flying Hazard
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Spain
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So, let's do it more graphically:

If the slats are dropped the air keeps following the wing curve increasing the lift. When the air detaches from the wing surface it stops lifting.

And, If you drop flaps and slats, the curvature of the wing is greater, making the air flow quicker over the the wing (because it has to travel longer distance in the same time) making the air molecules to be further one from another creatintg a void, a lack of pressure. Then the air under the wing presses it up to compress the air above it (Lift).

Even though, you could be right (We should test it ) that when you raise flaps, you are able to do HIGHER SPEED alpha flights by reducing drag, but never lowering the slats.

Cheers, Jandro.

PS: Hope you LOL the pictures.
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Old Jul 02, 2010, 09:20 AM
Flies to poles
Far far North +2 zulu
Joined Jun 2008
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Fullscale planes need loads of lift thats why they do it differently, because they weight so much. We in other hand a lot lighter planes, where we can fly more angle alpha. Thats where spoilerons come in play, to get more angle on the wing and still remain in control. If youd try to fly high alpha with flaps (huge airbrake in high alpha), you would stall out because you cause too much drag, and lose aileron effectiveness or youd have to settle for less angle. Spoilerons reduce the drag in high alpha, and you have control over ailerons in high angle cases.
The slats are just making the airflow stick on the wing, and not turbulance over the wing.

Your a smart guy, i know, but you speak more of landing and takeoff phases in full scale, where im talking high alpha stuff in styro planes.
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Old Jul 02, 2010, 09:42 AM
Fly, Crash, Burn,
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man, in this debate, i am getting so much info i was missing before.
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Old Jul 02, 2010, 10:28 AM
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SU-4ever:
You have the right idea however the drawing is wrong. The area of low pressure is generated on top of the wing, not on the bottom. Low pressure is suction...ie lift. Higher velocity equals lower pressure. Lower velocity= higher pressure. The air on top of the wing has to travel at a faster speed thus creating an area of lower pressure. Bernoulli's Principle...
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Old Jul 02, 2010, 11:07 AM
Flying Hazard
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Spain
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You're right , I mean, I know the lower pressure is over the wing where the air flows at higher speeds, the drawing is a BIG lapsus, I'm sorry!

Thanks for noticing!

PS: I've already corrected the picture.
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Old Jul 02, 2010, 01:25 PM
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Real aircraft and RC aircraft are no different. In fact, they are the same because they are all AIRCRAFT. Just one has a pilot and is scaled larger and one is flown remotely and scaled smaller. It is all relative and scaled. The aerodynamics operate the same. The only difference is that RC planes are typically overpowered thus allowing model pilots to do aerobatics and maneuvers that real airplanes cannot do as well (they can still do them).

If the flaps were to be raised both raised upwards equally on either side you would create spoilers. By definition spoilers kill lift and increase drag. This either allows an aircraft to descend or slow down or a combination of both. It does not create lift in regards to the four forces of flight.



It would however create negative lift (but that is detrimental to what we would want). Here is a handy link that demonstrates that: http://www.grc.nasa.gov/WWW/k-12/Vir...ane/shape.html

I think I understand what Kreot is getting at, using spoilers to slow the aircraft down and "deep stall" it while using power to balance what little bit of lift left. All the while trying to pick up a wing using tailerons, ailerons, or spoilerons. I get it, but it is not very conventional nor very efficient. Plus the stalling characteristics are typically unfavorable due to vortices coming off of the nose and the lack of wash out constructed into the wings on the Chinese foamies. It would be very tricky and in my opinion not worth risking on a beautiful and expensive model such as this.

Personally, having slats, flaps, and flaperons coupled with vectored thrust would be your best bet in achieving quality high alpha. Just look at the NASA HARV program to find out more. Also look at pictures of military aircraft doing high alpha passes at airshows. They have slats, flaps, and possibly flaperons deployed. There are no spoilers at all deployed.

Here is a pic of what the aircraft is doing aerodynamically. Notice flaps slightly deployed and full slats deployed. Also note the turbulent air coming off of the nose and a large section of lack of lift/laminar flow on the inboard section of the wings near the root.


This is all part of the fun though of RC's, being a test pilot and pushing your planes limits.

Now sorry for the thread hijack, back to this sweet Mig!
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Old Jul 02, 2010, 01:59 PM
Flying Hazard
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This kind of posts are always welcome!

Cheers, Jandro.
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Old Jul 02, 2010, 02:46 PM
Flies to poles
Far far North +2 zulu
Joined Jun 2008
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Your one right track, sort of loosing the lift on the wing, and holding it on the motors, but the trick is to keep aileron authority there. The difference is the weight of the full size craft, if they would be lighter, or if they had more power they probably would use spoilers in airshow stuff like slow high angle passes, but they choose to kill stuff, not do circus for us. Using spoilerons would not do anything else than be cool trick in airshows, thats why they dont need it.

Check this goofballs video:
RC F-18 High Alpha Flight Training! (see sidebar) (6 min 39 sec)
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Old Jul 02, 2010, 03:03 PM
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Quote:
Originally Posted by kreot View Post
Check this goofballs video:
I wouldn't call Dave Powers a goofball, he is certainly not one.

Cheers,
Henrik
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Old Jul 02, 2010, 03:07 PM
skunkworks
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Quote:
Originally Posted by hklagges View Post
I wouldn't call Dave Powers a goofball, he is certainly not one.

Cheers,
Henrik
Pioneer is more like it!
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Old Jul 02, 2010, 03:10 PM
Flies to poles
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I like Dave and hes goofyness, fronteron talk and stuff, not looking down Dave at all
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Old Jul 02, 2010, 03:12 PM
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Quote:
Originally Posted by hklagges View Post
I wouldn't call Dave Powers a goofball, he is certainly not one.

Cheers,
Henrik
He is ok...but this or his Girl is really annoying...from her voice, she must be blonde.


LOL.
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Old Jul 02, 2010, 05:03 PM
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Quote:
Originally Posted by neversommer View Post
He is ok...but this or his Girl is really annoying...from her voice, she must be blonde.


LOL.
Nope, she's not blonde
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Old Jul 02, 2010, 05:49 PM
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London
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I originally commented about spoilers aiding high alpha moves because I saw it used in Dave from RCpowers video (posted above). Enough talking and diagrams, the proof is there in the video, it works.


Quote:
He is ok...but this or his Girl is really annoying...from her voice, she must be blonde.
Oh and Dave is no goofball he is a genius and his girlfriend is brunette not blond, her voice may be annoying but I know many men would be greatful to have a wife that is into RC aircraft like she is.

PS. Sorry if this post sounds aggressive, I'm not intending to be so.
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