I want to make a remote controlled b 29 super fortress out of balsa wood. The estimate weight of the aircraft is about 10 pounds. What are the best propellers to use since I would like to fly at at least at 5 mph ?
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1$\begingroup$ Welcome to drones SE and thanks for asking! However, when asking what the best of anything is, answers will be highly opinionated. Could you add some more details specific to what you want to build? (weight, motor size, desired speed, etc.) $\endgroup$– Jacob B ♦Commented Nov 17, 2021 at 15:56
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$\begingroup$ Do you know what motor you will be using? The propellers for a combustion engine plane could be significantly different from propellers used with BLDC motors. $\endgroup$– Jacob B ♦Commented Nov 18, 2021 at 0:00
1 Answer
Work out what scale you're building, and look up the size of the real propellers. Then you can calculate the scale size propeller. You'll need to round it to the nearest inch.
A model like that will probably use propellers with a pitch that is 50-70% of the diameter, so if you find that 10" props are scale size, you'll want 10x5, 10x6 or 10x7 props. They'll probably all work, but more pitch will give you more speed at the cost of shorter flight times, so you might need to try them to decide which you prefer.
A 10pound model will need about 1000W of power in total, which is 250W per motor. If you look for motors of that sort of power, many will tell you the size of prop they require.
APC's "thin-electric" range is appropriate for that sort of power, and probably the most popular. They're not 'scale looking' but you should find the ideal size before investing in expensive scale props.
Finally, you can get reverse rotation props in some sizes. It's nice to run multi-engine planes with some clockwise and some counter-clockwise props, so it pulls in a straight line during take-off. Don't worry too much if you can't though, it's not essential.