I'v been flying my US 40 with a K&B 65 Sportster. I'm wondering if I should switch it with a lighter 46 BB engine? The K&B gives loads of vertical, but do to the extra weight of the engine and 5oz of lead in the tail I think it is hurting my overall performance. It doesn't seem as nimble as my old GP Big Stick 40 that I had a .46 in. With the K&B I am still a bit nose heavy, so could that also be hurting my performance? Has anyone flown one with a larger engine vs. a smaller engine like a 46FX? Thanks for the input!

If not absolutely necessary, never add lead.
1. Move the rudder and/or elevator servos to the rear.
2. Move the battery to the rear fuselage.

My method is to install the engine and throttle servos, then put the wing on and rubber band the servos and battery in various places until it balances. Usually I put the battery forward and the servos to the rear. This way I can move the battery to further move the CG back.

Mine has a 46FX with APC 12.25-3.75 prop, weighs 5 lbs, and has plenty of thrust. What does yours weigh?

I'm not for sure on the total weight but I am positive its alot more than 5 pounds. Joe, does yours seem to snap and spin quick? Mine seems to do a big corkscrew, and just doesn't want to twist up like my other planes. This is what makes me think it might be to heavy for its own good.

The model builds nose heavy as it is and I would not use the kit engine mount, but toss this out. It has been known to crack in time and several have failed. The kit supplied engine mounts are very heavy and I would recommend that you use a lite Du-Bro or Dave Brown unit. I used the Dave Brown engine mount.

I mounted both my rudder and elevator servo's in the aft fuse, and installed a different tail wheel assy.

I have installed three engines into my model, and it now has a Super Tiger .90 in the nose. I've no lead in the tail, and my first engine was a K&B Twister .61. The K&B Sporster is a very user friendly engine, and very reliable. I've use this engine in several models and it always surprised me with great handling and reliability. It is not a high revving engine, but mine swung a 13 x 4 and will give better vertical too with this model. I only used wood props on my gas models.

Find round brass tubing that will fit snug around your wing hold down dowels, and install the brass tubing. The hold down dowels will wear and change your wing incidence...and your model will fly like !#$%&*...mine wore almost half way through before I caught it and made the fix I've spoken of here. Ask me how I know... I would also suggest that you beef up the bulkhead that the wing hold down dowels penetrate into, with a small piece of hard wood. Place the hard wood on the top so that your brass tubed hold down dowels will rest against the hard wood and not auger out the holes were the hold down dowels enter into. This bulkhead is weak and needs added strength to support the wing. Balance your props...this helps.

Coat everything with in the tank compartment for fuel proofing...it will add longevity to the model...I do it to all models.

Toss out the fuel tank that came with the kit...mine failed. A Du-Bro 12 oz. dropped right in with out any modifications to the forward bulkhead.

Nice set-up, Bob. That's the way to put a big engine in a smaller plane without added weight.

I am also using a Dave-Brown engine mount, Sullivan Fiberglass main gear and tail wheel assemble. I sealed my tank that came with the kit with some silicone and so far I haven't had any problems (knock on wood)! Are you having any chatter or glitches by running long servo leds to the tail? I like your set-up and I might give it a try.
I'm running a 13X6 APC on my sportster and like you said it is very user freindly, I have no complaints in the power department!

Hay Buddy;

I have had no radio problems what so ever with the long leads to my servo's. I'm using Airtronics gear, 94102 standard servo's and an 8 channel Airtronics receiver. I'm using the main gear that came with the kit, and 3" wheels.

I used 1/64th. aircraft ply around the servo's in the aft tail section, and 1/8" lite ply inside the fuse to give the aft servo attachment screws something to secure into. Prior to installing the two servo's in the aft section, and before I attached the tail feathers, I ran thin CA glue all over the aft balsa wood. It's a very light weight way to add strength to this area. I do this to help strengthen the area where I removed the wood to insert in the aft servo's and stiffen it up.

I've run K&B Spotsters for years with great results, and very inexpensive overhaul/crash repair. Though the K&B .65 is not as strong as the .45 for it's size, it very user friendly, light on the gas for it's displacement and if you splurge and install a Perry carb...you can almost count a 13x6 blade rotation at an idle.

My Twister .61 lost it's muffler and I changed to the Super Tiger .90...it took a little work, but my vertical is awesome and indefinite. It goes up at the same speed it goes straight and level, so I must have reached a bit of a drag limit in speed, with this airframe. The airframe so far has handled the additional power quite well and built stock too. If you do not get to crazy with the model, and manage not to stuff it in, it will last a while. I love to fly this model, and it handles wind and rough air with the best of them. Once you master the power a bit, this plane is an absolute joy to play with.

Soft landings always,
Bobby of Maui

Bob,

Regarding the wing dowels...

I thought they were a bit on the soft side. I understand the reasoning and simplicity of the brass tubing trick, but it appears to me that the holes in the former would need to be enlarged to the point that the tube-encased dowels would now be interfered with by the top fuse sheeting- which slopes downward.

I'm wondering if soaking the exposed dowels with thin CA would provide enough surface strength to avoid them wearing down due to flight loads?

Steve;
The brass tube covered dowels worked just fine on my model, and they did not cause any problems with the upper sheeting on the fuel tank compartment.

Bobby of Maui