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Mar 25, 2021, 08:12 PM
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Discussion

Lucky lucky lucky !


UMX TT Lucky lucky lucky (4 min 42 sec)


So lucky to bring the UMX TT home in one piece .
Had wind N rain for a week , nothing like NSW , but put a crimp on RC .

This morning was the first decent morning in a week .
Those inverted skills were sorely lacking , showcased by the slight breeze that got stronger higher up .
There be downsides to light floaty planes .

Anyways , I made the mistake of trying to correct rather than just pull the plug when inverted and as a result Came very close to terrible firmness !
One meter or possibly less to kitting the TT .

30mm EDF Tales

Printed out a Test Stand mount for the EDF unit . And then thrust tested most of my fans .
The best = 2 4 blade fans .. Each averaging around twenty five grams of thrust at around three point two amps .
That's really bad ! ( Thrust )
And they are reaching peak RPM and then some on the test stand as I am using mains power ( less voltage sag under load )

Looks like the fans need far more design work ( to work ) ...
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Mar 26, 2021, 01:55 AM
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For the fan problem I believe that you face cavitation (tipical simptoms are lot of rpms and no thrust). Fans are supposed to work in flow. So my suggestion is to check thrust at different rpms and if you see that thrust is at first increasing and then decreasing back I suggest to try placeing a hairdryer in front of it to see if thrust improves.
Mar 26, 2021, 04:55 PM
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Not seeing that ,
I think efficiency is the problem .. I am hitting 25,000 RPM really quickly and then it takes more effort to get to 31,000 RPM where the thrust peaks at around 25 grams ..
@ 25,000 RPM thrust is around 17 or so grams . To get the thrust I want , the motor would probably need to spin to 40,000 RPM or more . ( I wont see that )

I suppose a brushed motor thats designed to spin to 50,000 RPM might be the go ?
I will have to test that hair dryer idea , sounds interesting ..
Problem is , the motor is already @ peak RPM . ( 31,000 + )


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