Centre of gravity question

Hi,

I know that some C of G issues have been discussed before, but I have a question on one of the statements made in the Vans site on the RV-12.

"The RV-12 can be loaded with full fuel, 50 lb baggage, and two 170 lb people and the CG remains forward of the 28% chord aft limit."

Does this mean that single pilot operation with full baggage and full fuel will put the CG behind the aft limit?

Thanks...Keith

Excellent question, but tough answer. It's certainly possible if the pilot is light in weight, especially in the demonsrator, N912VA. Remember though, one of the design changes in the "final version" is moving the engine farther forward to help with the c.g. issue, as well as give pilots a little more leg room. So to answer the question, if the final version of the -12 would be like 2VA, then yes, but hopefully it won't be a problem in the final kit version.

gblwy said:

Hi,

I know that some C of G issues have been discussed before, but I have a question on one of the statements made in the Vans site on the RV-12.

"The RV-12 can be loaded with full fuel, 50 lb baggage, and two 170 lb people and the CG remains forward of the 28% chord aft limit."

Does this mean that single pilot operation with full baggage and full fuel will put the CG behind the aft limit?

Thanks...Keith

Click to expand...

It all depends on where the pilot is relative to the C/G.

CG

Practically speaking, the pilot cannot choose where he/she is relative to the CG. The seat position is fixed. An aft CG problem can only be fixed by reducing fuel or baggage (undesirable - and hence the the intent of my question), or by adding weight*arm at the front. If the engine is moving forward, this will help things a bit, otherwise I'm gonna have to load up the panel with heavy toys to fix the CG problem. It would be unfortunate if baggage had to be installed in the passenger seat for CG reasons, or worse, ballast added in the single occupant case. Here's hoping...

Cheers...Keith

I didn't say he could change it,

gblwy said:

Practically speaking, the pilot cannot choose where he/she is relative to the CG. The seat position is fixed.
Cheers...Keith

Click to expand...

My point is...if the pilot is ahead of the center of gravity, then a lighter pilot will increase aft cg. If the pilot location is at the mid point of cg, then his weight won't matter.

Pilot Location

Agreed. I'm assuming, though, that with the cab forward configuration the pilot/passenger MUST be forward of the CG. The back of the seat is ahead of the wing spar isn't it?

This could be the first plane I'll fly where I need to put on more weight in order to carry baggage

Cheers...Keith

I'm sure Mel could explain much better than me, but from my understanding, most allowable c.g. envelopes normally fall in an area approx. 35% of the chord of the wing (1/3 back from the leading edge). By simply looking at the pictures of the current -12, I would guess that the people in the airplane are fairly close to where the c.g. is. If that's the case, then it wouldn't matter a whole lot as to how much you weigh in terms of c.g. location, just gross weight considerations.

But hopefully you're right Keith...