I want to mount a gopro on the bottom of a GP J3 Cub 40. I'm planning to fabricate a panel controlled by a servo that would let me control the pitch. So I can film straight ahead, straight down, or anything in between.

I'm sure that such a panel constitutes a huge control surface, and potentially as an air brake.

so I'm wondering if anybody has done something similar, and if so; how did it affect the handling characteristics of the plane?<br type="_moz" />

Cubs already have landing gear down there. It already creates a bunch of turbulence and drag. If you've ever messed with a Cub with scale shock absorbers down there, you probably didn't notice a major difference from a Cub without. There is a difference, but nothing to worry about.



Put the units CG straight under the a/c CG and you won't have that to worry about.

I've done some filming from above and never had much use for straight down. Sideways is way more useful.

Welcome to the site, skibby !!!

If you refer to the changes of angle of the camera during flight acting as a control surface, I believe that the worst case is the view straight ahead due to maximum drag.

However, for the low speed of cubs, it should be not too important as to disturb flight much.

Yes, it will be drag inducing some nose down pitch at high speeds, but that could be easily cancelled with elevator input or trim, IMHO.

I personaly think that what you want to do is not posible.The control of a Heli depends alot on weight and balence from the fuselage hanging below the Rotarywing.Putting the Rotarywing under the Fuselage would take away any control at all? I think Heli's are dislecsic anyway! The self rotating wing is the way to go. Check out my prototype.It's a much more efficiante way to get airborn!

Sorry I did'nt read all the replies you got.It wont make much differance if you put your wing under or over on an Airplane! As long as your c.g. stays where it is supposed to be.As for control you'll have to see? It may be better depending on what type of Flying you do.I have flown both types and with real planes High wings tend to float just above the runway when landing do to ground affect I think.Good luck It should stay pretty much the same as far as right rudder on takeoff.I can't think of abything it would affect AS FAR AS CONTROL SURFACES GO?

You need to go to bed, sleep it off, and start again tommorrow Charlie111. The OP is talking about mounting a camera under his J-3 Cub, he is worried about drag of the camera rig causing control problems for the aircraft.

My main concern is that it would cause the nose to pitch down and the elevators wouldn't have the authority to correct it, due to their much smaller size.<div>
</div><div>Secondly; the rig would basically be a large speed brake. This could be overcome with the throttle however.</div><div>
</div><div>What I didn't consider was the CG. If the camera was pivoted from the top then the CG would move forwards as the camera went from horizontal to vertical. (Looking down to looking forwards). This would mean I should pivot the camera from its CG, however this would make the rig require vertical movement and then rotation.  The only way around the CG I can think of would be to put a weight on the servo horn to move a mass backwards inside the fuselage as the camera went forwards.</div>

Skibby, I haven't tried mounting a Go-pro yet, but I have been playing with a Contour and some Key chain cameras and I also made several drop modules for dropping candy on kids at church. My drop module weighs about 6 oz when loaded with tootsie rolls. Make sure your Cg is a little towards nose heavy with the camera installed and shifted aft and you should be fine other than adjusting trim when you move the camera foward. You may have to reposition camera aft before landing if you don't like coming in hot for landings, but otherwise you should be ok as long as your cg is not too tail heavy. Nose heavy is managable, tail heavy on a Cub means it will stall with no warning . I can tell you that my .40 sized Cub is one of the most sensitive planes I have to adding things. If you have an 80 inch or larger Cub, it would probably be a better choice than a 70+-inch .40 sized Cub.<br type="_moz" />

 (Flying it in) helps with control on windy days also.It helps maintain a somewhat steady Airflow on the Plane!

Skibby, the drag from the camera down in that location will be similar enough whether it's pointed down or straight ahead that you won't notice any trim difference from pointed down to pointed straight ahead. I'm assuming here that it'll be proper side up when pointed ahead.

But there likely will be a few clicks worth of trim needed for the camera in place or not. Be ready for that.

Just put the camera near the cg. Then there will be no problems.
And put counter weight on if nessary.

Here on the top of the wing of aFuncup, and on the wing of the glider (with counter weight on the other wing)
<span class="hps alt-edited">Of course I have to trim it when its in the air, but not that much than expected.
</span>
[youtube]http://www.youtube.com/watch?v=gy-At1mX2xk[/youtube]

Funcup again

[youtube]http://www.youtube.com/watch?v=5TYlsgfwul0[/youtube]

Glider
[youtube]http://www.youtube.com/watch?v=HHf9iGqNInA[/youtube]

Here on the back of a90 cm flying wing

[youtube]http://www.youtube.com/watch?v=ux8Gh3xt-Pw[/youtube]

ME 163
[youtube]http://www.youtube.com/watch?v=fr0DguGUixA[/youtube]

Just do it.

S

Hahaha............those vids made me dizzy !!!!

You are a doer, indeed SpeedsterDEN !