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Thanks Ed,
I'm just trying to use something I have already rather than buying new stuff.
I understand IC cubic inches but the array of stuff to learn in the electric business is giving me head aches.

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I understand wanting to use what you have. If the A40 on 5S is flying what you have now well ..... just stay with a similar size and weight plane .... and you should be fine.
Something like and Inspire 60, or similar size and weight "pattern" plane would fly well on the A40 and 5S.
A 90-110 size plane (like the Focus II) is going to need quite a bit more power to fly well. I've been flying this size "pattern type" bird (Venus II, Showtime 90, Inspire 90) for 3-4 years now. I'll be glad to help you any way I can. The learning curve is not that steep, once you get over the first few hurdles .
Ed