CG location question
 

This is my third ARF. First was a Nexstar and then H-9 Pulse. I now have a VQ Warbirds P-51D. The "instructions" (use this term very loosely) say to put the CG at 132mm from the LE. I presume that I am to use the LE were it intersects the fuselage, and to check the CG with the plane inverted and the wheels in the upright (not down) position. I have used a Great Planes CG Machine (seems to work good) and have it dead level at 132mm. I have learned from reading other threads that it is better to be a little nose heavy than tail heavy. So, can you guys tell me how the plane will fly if the CG is off? I mean, if the instructions are off or wrong, or I have made a mistake, what are the tendacies (what will the plane do, if I can keep it in the air) if the plane is a little tail heavy or a little nose heavy? Thanks in advance for your help.
Pete

In case anybody wonders, I named the plane Lil' Squirt after my daughter's nick name. The numbers on the tail are her birth date. She got a big kick out of it. I painted the nose yellow and got the graphics from Bill Fulmer at www.customcutgrafix.com . He seems like a real nice guy.

RE: CG location question
 

Every plan I have built, the "suggested" CG already gave a slightly-to-very nose-heavy condition. Even full-sized craft have a "range" within which the CG must fall. Otherwise, they could never allow for the fat guy to sit in the back seat, or the skinny guy to sit up front.
Setting it there should be fine, but you should probably expect to need to move it aft slightly (as your skills and experience with that model progress), by removing weight from the nose or positioning the battery farther aft.

RE: CG location question
 

How it feels is really a result of where the CG is AND how much elevator movement winds up in your particular model. That is, if the CG is in the safe range and the elevator throws are not more than what's suggested in the instructions.

If the CG is toward the rear and the elevator throws happened to wind up less than suggested that model will often feel just like one that had the CG at the front of the range and the throws greater than needed. Give you an idea of how they work? The two go together.

Now, everyone is going to start yelling about noseheavy flies lousy but tailheavy flies only once etc etc etc. And they're right.

But experienced mfg's know their buyers. And they suggest a very tight CG range (like ONE place, so much for range) and very safe throws.

If this thread stays on the front page long enough, you should get the most valuable advice possible. Someone who has flown that sucker will wade in and tell you what his did. And that will beat all the theory you get into a puddle.

RE: CG location question
 

BTW, that was a neat thing you did with the s/n and the airplane's name.

Allow me to spin off with some off topic advice. Take your model airplane pictures with your kids holding the airplane. Some of my nicest pictures have my girls holding daddy's latest stunter. My little girl once told me she couldn't wait to be big enough to hold my airplane so I could get a good picture of it. Little did she know the airplane wasn't half the picture.

And that gave me an excellent reason to always have TWO airplanes that needed to be in the picture. See...... always have a good reason for the next airplane.

RE: CG location question
 

da Rock,
Thanks for the CG advice. Good idea with the two planes and kids. Sounds a little sneaky.;) I will take that picture over again with my daughter in it. My son who soloed last week was a little bent when he saw the name on the P-51! Little does he know that next year I am planning on getting the Top Flight P-47 60 and putting his nick name on it.
I put a Saito 82 on this plane and it was WAY nose heavy. So instead of alot of tail weights, I added an additional battery for the retracts, built a battery box and hatch half way back in the fuselage for both batteries, and added 1 1/2 oz of weight to the tail. I am planning on maidening it this weekend.
Thanks again.

RE: CG location question
 

:eek: maybe ok maybe not . CG locations have been known to be off sometimes by quite a bit due to designer error -it happens . slightly nose heavy will not hurt anything -just less responsive at first. better safe than sorry . full size planes do have CG ranges one for take off & another for landing-- fuel burn.