Kit modifications
 

I have decided to build a Bud Nosen Citabria and I've found that in itself is enough to start a very opinionated discussion. I have two questions,

First, the plans call for no right thrust or down thrust but that is also for a .60 size plant. I would like to put in a G-26. Is this way nuts? Since this engine would have much more power than the orginal plans called for do I now need to adjust my mounting angles to allow for more torque and power. I realize there is some beefing up needed to accommodate the added power and weight.

Second, which probably effects the first question, Im considering using a naca 1412 airfoil like the decathlon uses instead of the flat one used on citabrias or should I just build the thing and enjoy it as is.

SuperHoggie

RE: Kit modifications
 

To answer your question it would help to know what you expect to gain by the modifications. About the only thing the change to a NACA 1412 airfoil will do is allow the airplane to fly inverted with a little less nose up attitude than with the flat bottom one. It won’t have much effect on other flight characteristics. If flying upside down is of great importance to you, by all means make the change. Otherwise just go with the wing as designed.

Over powering by installing a G-26 is a little more involved. If you just want to have unlimited vertical climb the G-26 is probably overkill. If you are looking for good 3D performance, the Citabria is not a particularly good choice. The scale tail surfaces are too small and the wing loading will be too high, especially with the increased weight of the big engine. On the other hand if you want pattern (or more scale) type aerobatics It would likely be better to stick with the .60 (or maybe a .78) size glow engine and keep the weight down as much as possible. For aerobatic performance, beyond a certain point, keeping the wing loading down is more effective than adding power.

If you do go with the larger engine, I would start out with the same thrust setup as called for in the kit. If the cg is in the same location, downthrust isn’t likely to be required. A larger prop may require a little right thrust but only flight test will tell for sure. I would build the firewall straight and provide some adjustment that can be made during test flights. (Washers behind the engine mount are effective.)

RE: Kit modifications
 

Thanks LouW for the insight. Unlimited verticle is not a concern nor is 3D but the albiltiy for unlimited inverted flight would be quite a presence for this airplane. The specs on the plans say the plane should weigh 10 1/2lbs with a .60. This just seems weak for a aircraft of this size for anything but scale flying. A can very much appreciate the wing loading concerns. Even though the plane has a 109" wingspan, the overall area is only 1550 sq". I just showed a flying buddy of mine the plans today and he said pretty much the exact same thing about the engine mount setup. Any futher thoughts are welcomed.
SuperHoggie