I just had a crazy idea to make the cg adjustable in flight to see what would happen for certain stunt manuevers.

How about putting a screw jack running from the normal cg location to the back end of the plane, Then attach a weight to the track (maybe 4 to 8 0z) and use a three position switch to activate the motor to move the weight forward or aft. Can use limit switches to stop the travel at each end.

What kind of new manuevers would be possible?

How about tail slides so long that it'll look like the plane is flying backwards?

Ah, It must be getting late.

Just an idea.

The idea is not bad...



HOWEVER...........



The added weight would probably destroy the aerobatic potential of the airplane....


Soooo.....


I gues we are better with a static CG... one which will be a good compromise for aerobatics and stability.



My 2 cents....

Airbike,
I had the same idea a while back but like most things I'm always too busy to do anything about it! The first thing I thought of was putting a weight on a pushrod attached to a servo but as Maxime
quite rightly says its dead weight so will affect how the model fly's. So really you've got to use weight already there like the battery. I think it could be done but you'd need some very long battery leads, and alot space for it to move backwards and forwards. And you'd still need an extra servo to do it with. If that could be overcome you could have it coupled to your rate switch so when select 3d rates the servo drags the weight back and hey presto rearward cg all at the same time!

Andy

how about a wing on rails that slides forward/backward and a good servo to move it, no dead weight ( its safe to say the wing is working for its living!) just a servo, and a bit of extra mechanics.

servo moves wing forward with 3d rates 'on' thus moving the c/g back, it wouldnt need to move much at all....................


food for thought

great idea how about a varable moment arm mecanical system where by you can extend fuselarge length or shorten it by ascrew jack system or sliding wing or tailplain system the mind boggles

A sliding weight in a plane is not a new idea. It has been used many times in the past. Although I have never seen it made adjustable in flight, it wouldn't be all that hard.

Possibly, like you mentioned, a screw jack and a sail winch servo.

You don't need a lot of weight,.


Now get to work on it...............

How about pumping some water between a forward and rear bladder tank with a fuel pump?

Mark