Dusters maiden and Prop Selection

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.


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:


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:


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.