11 x 3.8 APC SF vs. 11 x 4.7 SF APC? - RC Groups
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Jan 31, 2004, 11:10 PM
Shortman's Avatar

11 x 3.8 APC SF vs. 11 x 4.7 SF APC?

Alright, seeing the newer 11 x 3.8SF, would you say the 11 x 3.8 or 11 x 4.7 be better for 3d. What prop is more efficient at a lower throttle setting, say 1/3-1/2 throttle. What produced more thrust.

I need the best prop for the Attitude with a Hacker B20 15L 4:1 with 7C Thunderpower 3S 2100mah battery pack.

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Jan 31, 2004, 11:16 PM
Nimble with Gimbals
Power Systems maybe?
Jan 31, 2004, 11:26 PM
Mom says I'm special...
beafraid8's Avatar
Typically by increasing pitch you'll increase the thrust less than you'll increase the current. Can the battery handle it? It's a $2.50 investment, your time asking is probably worth more than the prop. Just watch your battery temp carefully.
Feb 01, 2004, 02:35 AM
Shortman's Avatar
Yeah, sorry about it being posted in the battery/charger forum, thought I was in the power systems for a minute. Could a moderator please move this thread to power systems.

I know by going from a 10 x 4.7 SF APC to the 11 x 4.7 SF APC I increase thrust tremendously and it becomes a more efficient running motor for 3D while pulling a few more amps at WOT, which, with the extra thrust, you dont need.

I am really just wondering if someone already has tried the two props and compared the results. The battery will have no problem handling these props or the amps they demand as long as I keep the throttle reasonable, which like I said before, will 90% of the time be under 1/3 throttle which is enough if not more power to hover.

Feb 01, 2004, 07:37 AM
Registered User
On a 11x4.7 you would have 32oz of thrust at 16amps. This should be fine if you manage the throttle and don't stay at full throttle for too long. On a 10x4.7 you would get 27oz of thrust at 12.4amps. You could stay at full throttle all day long, but your verticle would suffer. If it were my plane, i would use the 11x4.7 and just watch how long i'm at full throttle.
Feb 01, 2004, 01:12 PM
Shortman's Avatar
Anyone try them side to side comparison? I know the 10 x 4.7 is the outdated prop and the 11" dia would give best power.