RE: Balsa USA Bristol M1 conversion to electric - how to?
On a plane such as this, even having modest power (say about 400 watts) will work well provided that it goes into a large enough propellor. Having said that, this plane would probably be happier with 400 watts going into a 14x10 prop than a 13x8. I am just using these props for example purposes. I think that the AXI 2826/12 will work, but I think that you will be limited to a 13x8 prop or so if running it on 4S. You can always run a motor at a lower voltage than recommended, so a 4120/14 would probably work on 3S or a 4120/18 on 4S. Either way, you would be able to spin a 14 or 15 inch prop at 400 watts or more. These WWI planes have short noses, so having a heavy motor may not be much of a hinderance. Either way, even the larger motors are a little lighter than the .46 they replace.
I am currently building a BUSA Eindecker just for the fun of it. The power will be a BRUSHED Astro 15 cobalt running through a 4.69:1 gearbox. I will probably run it on either 4 or 5S and try to spin a 14" prop. This plane is known to be lighter than the Bristol, so I am not too worried about having enough power, even if it is in the 400 watt range.
Good luck,
Teo