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Old Oct 30, 2012, 09:02 PM
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Build Log
larger scale F-22 (thunderbird)

I know there are no actual F-22 thunderbirds out there but the paint job was just irresistible. Well this is my first attempt at a build log and this is my F-22 flown of tailerons only.

My goals for this build were very high i had an engine that was for a front prop plane and i wanted to put it on a pusher. Due to my lack of flying experience of only (4 months) i chose to go with a tried and true design the F-22.
I wanted this plane to:

-take off on its belly
-attempt knife edge (with a hidden rudder)
-have good vertical climb
-and the ability to perform roles, loops and inverted flight

Well what i got was a very heavy but capable plane, the rudder had to be abandoned due to its obstruction of air flow and it causing the plane to be very tail heavy. In addition i have yet to get the plane to belly take off as well the nose just digs into the ground.

but as for everything els it went very very well.

My big question now pertains to thrust angle, I have an elevated mounting arrangement to help with prop clearance and currently the prop is pointing horizontally in line with the wing, my question is should i give the prop some down thrust and how much???
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Old Oct 31, 2012, 12:21 AM
Fremont, CA
United States, CA, Fremont
Joined Jan 2009
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Very nice build!
I think that if you put some smooth tape on the belly and curled up the bottom of the intakes it might do better off the ground. A slight downthrust might help the takeoff too, but I don't know how much.
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Old Nov 01, 2012, 10:14 PM
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Thanks, i planed on tapping up the bottom to help with the retention of the paint job but that might definitely help the take of as well i also will be bringing some washers out to the field so i can play with the thrust angle, i will post some video shortly.
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Old Nov 02, 2012, 09:01 AM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
3,161 Posts
I wouldn't put any angle on the motor. It is close enough to the centerline that I don't think it will matter much, but it could change your performance power on and power off if you have angles on it.

Just try it straight first but put the motor so the screw holes are straight up and down. That way if you have to add any thrust angle, you can just slide a spacer behind the motor base.
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Old Nov 02, 2012, 09:21 AM
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United States, CO, Colorado Springs
Joined Aug 2003
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If thrust line is much above the CG and CP, power on vs power off is going to change the performance either way.

Agree that angles are unlikely to help, though. The TV paddles are going to try to push the aft end downward, so if the airplane can rock back on its heels you'll get some lift and some sliding action. You might try shaving more off the bottom of the nacelles at and slightly ahead of the prop so it can tip more there.
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Old Nov 02, 2012, 10:34 AM
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United Kingdom, England, Bristol
Joined Aug 2009
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Trial & retrial One of my similar pusher style models has thrust angle such that the motor-shaft alignment projected is through the nose of model (about 4 degrees). If glide is level, when you power-on where does it go ? Ideally it carries on but faster, then change nothing
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Old Nov 05, 2012, 04:40 PM
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F 22 thunderbird scratch build RC plane (2 min 55 sec)


Here is some video it was windy today so i did't go crazy, at the end you will see me attempt the belly take off unsuccessfully
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Old Dec 05, 2012, 06:54 PM
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ok well i was happy with how this build came out but i was left not accomplishing some of my goals.

So this time i am going to try something different...
For this model i will be using the F16 tentative size is a 39'' wing span and a 57'' length. this will be a full profile plane with a 11x8 prop Below are some concept drawings that i will be using to develop the plane.

design improvements on this will be a larger prop slot to accommodate the 11'' prop and i will glue in support rales where the fuselage ends to increase strength these will be shaped like bombs.

also as recommended from the build forum i will use the exhaust piece as a rudder so i can get that knife edge!

as recommended above i will be running a elevator only and separate ailerons due to the size of the model


QUESTIONS?
to blow these plans up can i do that on a home computer or am i stuck going to staples?
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Old Dec 05, 2012, 08:22 PM
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look for

Do a search for home depot foamy f-15 or f-22 thread . it shows how they shaped the belly to takeoff. you need the wings at a positive angle of attack. Dave
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Old Dec 05, 2012, 08:48 PM
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when you say a positive angle of attack you mean that the wings resting will be pointing up? right, this would make sense mine has the nose pointing at the ground... maybe a front wheel only could prop it up and give it the lift it needs without too much weight
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Old Dec 05, 2012, 11:24 PM
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Yes, the wings need to be angled up a bit and not level. If they are angled down it wont matter how fast your going, the air over top of the wing will keep pushing it to the ground. Acts like a spoiler on a sports car. Or next time your driving down road, stick your hand out window. If your hand is angled down just a tad, the wind will push your hand down. Have to get it above level for your hand to lift up
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Old Feb 02, 2013, 06:52 PM
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Just an update for everyone who helped me on this build, I was finally able to get it to perform take offs from the belly... all it took was some snow.
I took video but there was a smudge on the lens so it wasn't the best but you get the idea
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Old Feb 02, 2013, 06:53 PM
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F 22 belly take off (1 min 53 sec)
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