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I recently finished the FT Duster, I’ll not go into the build since the video on Flite Test goes through the build so much better.

http://flitetest.com/articles/ft-duster-build

The maiden flight could have gone much better:

I reduced the throws slightly and increased the expo a little more, reduced the size of the battery I used from a 2200mah to a 1400mah 3 cell. At Mels suggestion I also removed the cab. All this moved the COG slightly back so it is on the back side of the spar in the wing.

I don’t have a video of this, but this made it a much easier plane to fly, still a little twitchy and under powered but much better.

So I then decided to pick a better prop I had a few to choose from:

20140101_120047r

from left to right an 8×4.5 triple blade, a 6×4, and 8×4 which was on duster for its maiden, an 8×6 orange, and 8×6 black and a 9×5 orange prop. I then setup Duster with an amp meter and anchored it through a set of scales to give some idea of the thrust generated:

20140101_114247r

Although the measurement of the trust is by no means perfect it should give some idea of how good each prop is. The motor that is in duster is a 1580kv motor with a 20amp 14.8volt maximum power rating, so I have installed a 30amp hobbyking speed controller. I will be running it on a 3 cell (11.1 volt). The results of the current draw and trust measured is shown in the table below:

Prop Max Current (amps) Max Thrust (grams)
6×4 10 Did not register
8×4 16.5 220
8x6Orange 23 250
8x6Black 25 320
8×4.5 Triple 27 520
9×5 27 320

Apparently a plane flying through the air will take approximately 10% less current than the same plane static on the ground (due to the air movement over the prop, so I have found on the internet). Based on these numbers, although I think that the 8×6 black and orange trust figures are skewed by the setup, but I would say that the best prop would either be an 8×5 of the black type or the 8×6 orange prop, giving the maximum thrust with closest to the maximum power of the motor, and running it on a 3 cell should give the extra allowance to mean that it will take the current tested without burning out. The triple or the 9×5 prop would give more trust, but are both too far above the motors maximum working load current.

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