To make a really long story short, I now have a 46 size VQ warbirds P-51 with a OS 46AX that weighs 7 lbs. The box says flying weight to be 5.1 tp 6.0 lbs. Will this even get off the ground, and if so, will it stay in the air for long?
Thanks

I think it should be okay. Just keep the speed up. Worst comes to worse, you have to take-off with 15* of flaps and land with full flaps and a lot of speed. That plane won't have ballistic vertical out of a hover, but no mustang should .

There's only one way to find out.

Based on no aerodynamic equations (I wouldn't know one if it hit me in the face) it should fly. It'll take a lot of runway to get airborne and land hot. No guarantees on how well it will fly.

Now if you said 10 lbs...

all you can do is test and try, if the power isn,t there go up to a 55 ax. or better still with any war bird use a 4 stroke such as the 70.

Yes, it will fly fine. I own and have flown scale aircraft that are very heavy, much more so than the specs. I have also flown stuff with a wingloading that most people here would consider extreme. I have never had a problem flying any of them. Especially with scale models, weight isn't the only measure of flight performance. I actually prefer a little extra weight with my scale models. I find it makes them dampen slower and makes the aircraft more smooth in maneuvers (more scale flying). Make sure everything is set up perfectly and don't set the CG too far forward. Many people are afraid to move the CG toward the back of the given range, but I always find the models fly much better that way. The range the manufacturer or builder gives usually errs on the forward side anyway.

Well it flew, pretty good actually. The plane was repair project. I will try to post a little story in the "crash and rebuild" forum when I get a chance.
Thanks for the advice.