TD to TRI

8 posts in this topic

Posted

Question for discussion? I was ask the other day, and I couldn't answer it, about the CG on changing from a tri-gear to TD or reverse. I don't think the CG would change any if one made the switch. The CG range is mainly for in flight and not sitting on the ground. Only important thing is to have the gear placement correct so the fuselage either sits on its tail or sits on the nosegear when parked. Rotation speed or angle might change a bit but once in the air everything should be as originally designed (CG range). Is this reasonable or is there something I am not considering.

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Posted

The main gear itself comes aft, so it will shift the empty CG aft a bit (but not very much since the arm is so short).

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Posted

This is true. But it should not affect it in flight which is where the GC range is critical. There lies the problem, the CG range is determined from weighing it at the wheels and doing the math to arrive at the empty CG point. So there would be a difference in arm moments in figuring the CG. I told the person who ask me that its a snowball effect. I wonder how Avid does it in their convertible fuselage? In the air it doesn't know its a trigear or tail dragger. Except for a few added pounds for a nose gear and maybe some drag. Some aero-nut-ical engineer could figure it out pretty quick, but I ain't one of those. Probably simple math to figure it out. Airframe modifications, aside of course. That's a different ball game. Either way, back to the old saying, buy what type you want to start with.

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Posted

It should be pretty easy to figure out mathmaticly if you know the weight of the main gear and wheels, the nose wheel and gear and tailwheel and spring and the distances involved in each.  I would guess that moving the mains back to the tri gear configureation and adding the nose gear would end up being a wash CG wise.  The thing that may end up shifting your CG forward is removing the tail wheel and tail spring.  But it is just a guess, the right thing to do is the calculations.   JImChuk

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Posted

It’s negligible. Mine went tri to td. I still moved the battery and elt to the tail for cg AND added weight to make it fly better. Cg at 15-16 “ is sweet!

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Posted (edited)

I know it can be done and has been done but a friend of mine really doesn't want a tail wheel airplane. I suggested a C-150 might be a better choice for him. I personally don't think its worth the trouble unless it was designed to be both. Seems there aren't that many nose gear Avids or Foxes. So that should say something.

Edited by Allen Sutphin

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Posted

it says that the airplane market runs on such low margins that they cant afford to put nosewheel weldments in. I think the most valuable Avids and KF's are the ones that can be converted. It's a very nice feature to have and makes the planes much more marketable.

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Posted

I'd say they are more valuable, not that many of them. Supply and demand.

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