I talked to Mr. Hostetler, and he said there was about 3.5lbs - 4lbs worth of gear for the electric motor (switch, motor itself, ESC, batteries etc.). He couldn't be sure. His electric plane uses a Hacker C50. He also said that 50cc is the max for this plane, and earlier did say the DA50 or equivalent would be a good choice.

I also talked to Scott over at Brillelli and he said the 46cc swinging a Xoar 22x8 pulls 22lbs. The all up weight of the 46 is 3lbs 14oz with a rear dump muffler, and a side dump with be about 3-4oz. less. In fact, let me just quote his e-mail real quick. I hope he won't mind.

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The 46 is about 3lbs 14oz with a rear dump muffler. A side dump would be about 3-4oz less. Power is the same with either muffler. For a plane that light, 3D would be no trouble at all. I mean no trouble.It will hover a 15lb plane, so at 12-13 lbs it will be a rocket. Bisson makes a muffler for the engine as well, but they get $75 for it and it is not that much lighter. Just a little quieter.

Thank You,
Scott

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So that means it is possible for the Brillelli 46cc to come in at a AUW of around 3lbs 10oz, maybe a tad lighter. That's actually not bad, just over 3.5lbs. I am just wondering if it wouldn't be an easier and simpler decision to use a 50cc engine. The plane sits 13" from ground to prop hub, which translates into enough prop clearance for a 23" - 24" prop.

My most significant concern is weight and balance. I want to keep the plane light, and I don't want to have to add dead weight to balance it. What I may do is build the airframe first, without the engine box/mount etc., then weigh and balance it. This would tell me the weight I need, as well as the power. With 1100+ sq. in. of wing area I think going up to 14lbs would still make it an excellent IMAC and 3d plane, but I could of course be wrong, given my lack of experience in this area. See my post above for the wingloading at 13lbs. It's just a tad under 25oz/in.

What has me most confused now is that I have some people saying a 40cc (ZDZ40, Brillelli 46cc, Taurus 42cc [which isn't even in production anymore]) class engine with the plane at around 13lbs will be more than enough for any maneuver, 3d or otherwise. On the flipside, I'm seeing where others are saying that a 13lbs plane with a 40cc engine will be simply adequate. Of course, each person's definition of what is "adequate" and what is "more than enough" is probably different. Unfortunately, there is no standardized method for calculating what is "enough" or "not enough" power for each plane. There could be, because mathematics is universal and all this could be easily and almost perfectly calculated, but, alas, manufacturers and hobbyists don't seem as interested as they should be in such things.

Anyway, yes, I think I'm getting much closer to making a decision. At this point I've narrowed it down to a few manufacturers (ZDZ, Taurus, DA, Brillelli) and two engine classes (4xcc or 5xcc). This may change, especially since I'm very likely going to forego purchasing the engine until after the airframe is complete and most of the radio equipment is installed. This may make the general construction and engine installation more difficult, but it could possibly save me a lot of money and time in the end.

At least, this seems like the wise decision.

I may go have another look at the electric option.