I've flown your Piper Cub with 3 servos (separate ailerons) and have mastered flying it. I used your mps-2a motor rather than the mps-1a motor.

Do you think that after mastering a rk Cub I'd be ready to try the rk B-17? I was wondedring how fast the B-17 flies with four motors.

From : Don Stackhouse

The B-17 flies about the same speed as the Cub. Handling is also very similar to the Cub (in fact when I designed the B-17, I borrowed some of its aerodynamic features from the Cub), other than the roll rate. The B-17 has a turning radius similar to the Cub's, but the roll rate (i.e.: how fast it can roll into or out of a turn) is "scale-like", in other words, similar to that of a real B-17. For that reason you have to plan ahead on your flight path so you can allow room to get in or out of a turn in the space available. We've flown it in a basketball court, but it's really tight; it's much more comfortable in something like a golf dome, or outdoors. Reserve power is quite a bit more than a Cub with the single motor MPS-1A, but not as much as a Cub with the twin motor MPS-2A.

The B-17 is also designed with separate rudder and ailerons as the standard setup, and it does need coordinated use of rudder and ailerons to get the best response to roll commands. However, that's how you've been flying your Cub already, so you should not have a problem. Of course the other option is to mix rudder with ailerons in your transmitter. That works OK, but learning to use both sticks is better. In that regard the B-17 is an excellent aileron trainer, big, slow, very stable, gives you time to think, but requires use of both control sticks to get the most from it. Although not generally considered a "scale maneuver", it does thermal quite well. Ten foot diameter turns are not a problem once you get it rolled into a bank.

However, top speed, despite the four engines, is fairly slow, so it's not the best airplane in a lot of wind. Covering the underside of the wing to make the airfoil flat-bottomed instead of highly undercambered will help the penetration into the wind considerably, although it will also make it faster indoors (not a good thing for indoor flying in small rooms). Just frame around the ailerons with some balsa strip to give you something to attach the covering to ahead of and behind the hinge line, and cover the bottom with lightweight covering such as "Litespan" or "Micafilm" from the inboard engine nacelles to the tips. Don't bother with the portion of the wings between the inboard engines and the fuselage, there's too much trouble working around all the radio gear there, and it won't make enough difference in the total drag to be worth the trouble.

The B-17 is really a tame airplane both on the ground and in flight, big, majestic and very smooth. It's a lot more to build than the Cub, with four engines and their wiring (although a Pixie 7-P speed controller is fine for it, the four motors pull a total of about four amps), and all the extra scale details (as well as the mechanisms for the droppable bombs), and of course large airplanes are not as strong in a crash as smaller airplanes, so we don't recommend it as a primary trainer. However, as long as your flying area isn't too constricted (a little-league ball diamond is more than enough room), if you can handle the Cub, you shouldn't have any problems flying the B-17.

Don Stackhouse
DJ Aerotech