I crashed my Sig SE this past weekend while 3Ding a little too low and broke the fuse in half. So to get back flying quickly I ordered the Tower Fun 51. I will be putting the Magnum 52 from my SE in it. I will be modifying the rudder and elevator to make them larger and include counterbalances. What I'm wondering though, should I modify the fuselage to mount the rudder and elevator servos at the rear of the fuselage to help balance with the Magnum, or just leave them in the wing.

Hmm.... where to start.... The counter balances on the control surfaces are a good start, also possilbly incerasing the aileron area as well. I have a tower "extra Special" profile kit at home. If the P-51 is anything like that kit, it will be heavy. Reduce the lite ply in the kit as much as possible, use the lightest components possible and the aircraft may have a fighting chance. I am not really qualified to say if the servos should go in the tail or not, but my guess would be to leave them where they are, remember a little weight change in the tail leads to a big weight change up front to compensate

Leave the servos up front, it has a really short nose. If you can built the tail lite, add 2 inch's to it. But anyway you go it isn't a good 3d plane at all. A Burrito can be built and covered in the time it takes to frame up a fun 51, is a lot stronger in a crash, 3d's 300% better.

Add two inches to the length of the fuselage or the rudder? It's going to have a Magnum 52 on it so there will be a little more weight up front to counter the additional weight in the rear.

Both would be good. 1 inch to the elevators, 1/2 inch on the ailerons.

I'd say the ailerons and elevator are OK without modification. I'd add some area to the rudder instead. You'll need it if you want to hover. If nothing else, definitely strengthen the area where the landing gear mounts by replacing the balsa outer skin with light ply. That area is notoriously weak on the Fun 51 / Extra Special.

It's not the hovering machine that the Burrito is, but it's still a blast to fly. You wil love it. The Magnum 51 is a lot of engine for the Fun 51. Mine weighed just under 4 lbs with an Enya 45SS. You will go vertical like a rocket.

I have been flying the extra special, basically the same plane just a different profile, for the last 4 years. I never thought the plane would last this long, but I now consider the plane the most reliable and relaxing plane to fly that I own. If I were to build another I would recommend all of the above modifications, plus a couple of additional reinforcements. The plans call for you to trim away the outer balsa sheeting so that the gear sits somewhat flush with the fuselage. I built it as instructed and this makes this area of the plane to become very weak and makes it prone to breaking. I would recommend just bolting the gear to the balsa itself or if you are hard on your planes also using some 1/8 ply on either side of the gear mount to make this problem area "rock solid" Also the landing gear that came with the plane was very soft and was very prone to flattening out, I have replaced with the dubro gear and absolutely love them. I orignally built this plane to be as light as I could by replacing some of the very hard balsa that came in the kit with some lighter stuff I had sitting around. I also tried using some lighter components like a ThunderTiger 42 and hitec225 servos and without much trying I was able to get the plane light enough to hover with the TT42 and a 10x4 prop. 1 month ago I doinked her in and ripped the nose off (From all of the landing gear repairs) I have just about got her all fixed up and ready to fly again. I just need a quick trip to Home depot to get some longer bolts for attaching the landing gear over the new reinforcing plates I needed to apply. I also upgraded the engine to 46fx and this should make this plane a rocket. Good luck with yours!

- JK

I forgot to attach a picture of her in her most recent state, please forgive the orange & white flames as I just used whatever I had lying around.

Well, the only other engines I have are a OS 40FP, 40LA, 46LA and a Saito 1.00FS. I doubt if the 46LA is enough engine to hover, so the Magnum 52 is pretty much my only choice. I'm still thinking I should build in rear servo locations just incase I need the weight in the tail to balance with the Magnum. Have you noticed if the control rods running all the way back from the wing area induce any slop in the control response?

My Fun 51 had a Enya 45ss...which weighs about 15 ounces, probably several ounces lighter than your Magnum. It balanced about perfectly with the Enya. At one time I added an ounce or two in the tail to try to improve hovering, but that made it almost too unstable to land. So yes, you might benefit from moving at least one servo toward the tail to make up for the heavier engine.

Your 46LA would certainly fly the plane and would probably balance nicely with the wing mounted servos. I expect it would hover but I doubt it would pull out with much authority.

I did not notice any problem with slop in the control surfaces using the stock push rod setup.

Thanks for the info JPMacG