Old motor to modern equivalent.


Elite member
So, Years ago I started a Great Planes Electric Cub. I stopped before I had started to construct the wings, as I was unsure of my ability to put on MonoKote. Now that I’ve done a whole bunch of crashing…uhm...flying, I think I’ll finish off the Cub and try to fly it. When I grabbed the box the other day I was wondering what size motor to use on the plane. Looking in the box I found this old Great Planes motor. What modern motor would be equivalent to this?


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Legendary member
Hard question to answer with the given information.

I would think the best thing to do would be to get the weight of your model and a good estimate of the wing loading it will have and use that information to decide how many watts or how many grams of thrust you will need to fly comfortably...


Site Moderator
Staff member
I agree with @Hondo76251, watts per pound will get you in the ball park. In addition, I would choose a motor that uses a prop similar to the size used on the original.

Here are some guidelines

50 to 70 watts per pound is the minimum level of power, good for park flyers and lightly loaded slow flyers.
70 to 90 watts per pound is perfect for trainers and slow-flying aircraft.
90 to 110 watts per pound is good for fast-flying scale models and some sport aerobatic aircraft.
110 to 130 watts per pound is what you want for advanced aerobatics and high-speed aircraft.
130 to 150 watts per pound is needed for lightly loaded 3D models and ducted fans.
150 to 210+ watts per pound gives unlimited performance for any 3D model.
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Elite member
Thanks! I still haven’t decided what to do with the balsa Cub. At this point if I want a Cub it seems easier to build it in foam board.