The last one you listed is the sensible choice both in performance and suitability for the airplane. It is the 46AX series 11 that I first recommended in Post 20, it should be at the top of the list. The saito 40 would also work ok. Both of those gas engines will incur considerably more weight since you must remember you will be adding an ignition system to be mounted somewhere and will have to carry a second battery pack to be charged separately each time.

The LT-40 is not practical for a gas engine. You are going to engineer yourself into an impractical ship and likely be very disappointed. There are a lot of those out there mostly they never make the trip to the flying sites since the are so unpleasant to fly and become hanger queens.

The Senior Kadet has a 78 inch wing in kit form and the LT-40 is 70. It is not the same structure and built much lighter its my opinion that even it is far better off with glow engines. Here is a case in point, Last year when I ran my first Kadet Senior pylon races races one the fellows insisted on using some gas engine that is 15cc I cannot even remember the engine. At any rate it was a three round event and he could only keep it running just one round and the performance was pathetic. Even one of the Kadets using a 35AX was far better.

John