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:
http://www.youtube.com/watch?v=l4SJHfTz_IA
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.