Swing wing CG probs! Help!
 

Hi all,
I've always wanted to play around with building a swing wing.
(Like the F-16 or 14)
When building, are there any major points you have to take into account about C of G position?

How DO you work out the C.G of a swing wing anyway?

Help!

Swing wing CG probs! Help!
 

I'd really like to see a picture of that swing wing F-16!!! :D

Although I have never built a swing wing model I have discussed the F-14 with Mark Hambleton of DCU models. He said that they originally weighted the wingtips of thier F-14 in order to maintain the CG in relation to the center of lift as the wing sweeps. He also told me that one of his customers' models had recieved some wingtip damage on landing and had been repaired at the field (minus the wingtip weights) and had still flown just fine at all sweep angles, and after doing some tests of his own Mark decided to leave the weights out of future kits.
Mark designed that model, so I would guess that he knows what he is talking about. :)
As far as working out the CG, I would suggest that you first find the CG for the foward sweep position and the rear sweep position, then for several other postions in between those in 10-15 degree incriments.
I think The USJRC site has a pretty good article for how to figure CG on a highly swept wing planform.
One other interesting thing that Mark told me about swept wings is that it actually is more difficult to move the wings rearward than it is to swing them forward :spinnyeye , if the sweeping mechanism were to break somehow the wing(s) would actually move forward while in flight not backwards as you would expect.

Kevin Whitlow

Swing wing CG probs! Help!
 

Right! So by measuring the C of G in the forward swept position and then at points as it sweeps back I can work out whether I need to add weight at any points.
Would it be worth making some kind of moveable weight so as the wings were moved the weight would auto balance it?
It's a good idea but if I have to do anything complicated I know it'll never get done!
I'll check out that site and see what I can find!
Cheers.

Swing wing CG probs! Help!
 

Check out this thread. http://www.rcuniverse.com/showthread...185&forumid=26

You can probably get answers to your questions from Adil Nasim.
As you can see from this thread, he has a beautiful F-14.
JAA

Swing wing CG probs! Help!
 

Cheers!
I'll check it out!

Tornado Project
 

I am working on a swing wing 98" Tornado. I will let you know how it goes StickZ.

Swing wing CG probs! Help!
 

Like Kevin, I also had the experience of working with Marks F-14s. Mark had a smaller version that I flew here on the slopes as a glider. Weighting the tips, was the easiest way to go. Having flown with and without weights as well, I can tell you from my own personal experience that if you dont, then the pitch response gets really slow if you dont shift some weight aft. On a third model, we used some heavy paint application on the wings and that did the trick as well.

Best of luck,

Ray