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Old Aug 01, 2012, 07:40 AM
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Australia, VIC, Melbourne
Joined Nov 2006
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I have 99% finished it off. I have to take/add the pics of the final bits done.
The battery area and wiring paths, and the canopy 'antenna'/finger grab doovey to make it simple to get it off.

I did a thrust test..... by hand. It ALMOST holds itself in the air vertically.
AUW with the main, for now, 5S 3000mAH 30C battery I will use is 1180g
Thrust is 1030g
42A and 764Watts. I guess I was happy with that lowish Amp draw!
This is static and with no change to the cheaters (not cutting some of the 'bridges' out).

That is quite a way down from the bench 1.4Kg and 50Amp/840W it can do. So I would think if it can get a bit more inlet flow it should gain 0.1Kg to 0.2Kg
Then I had the brainwave (a simple one!) to test it with the hatch off !
Thrust rose to 1120g and input power increased to 43A/800W

Getting close to 1:1 and it shows that if it can get a bit more inlet flow it will gain from that - which people (and myself) really already knew anyway. But I guess it shows that even the best inlet airflow increase possible - which won't match an open hatch size - won't be helping any more than that 0.1Kg thrust gain approx.
In flight at speed it might do a bit better than these numbers above anyway.....

I am tossing up on opening up those top-side 'panel covers', to make the sprung cheater doors idea, but I don't have the bits to complete the spring hinging for now. I would have to leave them fully open all the time, which who knows if that would be good or bad..... I would actually guess it would be closer to unimportant, than to mattering. So I will toss up on that.
I am thinking to just fly it as it is, seeing it is 'flight ready' now, and then see how it flies and thus how important any more thrust really is. And seeing that all it will gain is a maximum of 0.1Kg approx, for a cost of 1A area, it might just be too much effort to bother.

There is also a chance that the ducting will be quite optimal for flight speed just as it is. So if you cut out the lower cheater holes, to get a gain from better static thrust, it could actually lose out in top speed in flight. So you gain just in the take-off/very low speed flight region, and lose at higher speeds to top speeds.
This is why a 'doors' system is better.... it works across the whole flight range. So I won't be cutting out the lower cheaters because that is a permanent non-linear curve of gain/loss across the flight speeds range.
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Last edited by PeterVRC; Aug 02, 2012 at 12:24 AM.
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