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05-07-2005 11:32 PM  12 years agoPost 1
RCfun

rrApprentice

Denmark

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Hello all.


Today I was at the field and made some measurements using an optical tach also from model avionics. I tried different % settings on the TJPro channel and measured the corresponding head speed. The list shows my measurements (gear ratio is 8.7:1).

15% -> 1420 RPM
20% -> 1530 RPM increase 110
25% -> 1590 RPM increase 60
30% -> 1670 RPM increase 80
35% -> 1730 RPM increase 60

The measurements where taken with the heli on the ground. The tach should be accurate to 10 RPM +- 2.5 RPM.

The TJPro should have a linear increase in RPM so why the differrence in the RPM increase for each 5% aux channel increase. Are these differences to be expected (I assume they are)? My real question is how I should proceed in order to construct a fairly accurate function mapping aux output % to RPM so I do not need at tach in the future should I decide to change the RPM.

Thanks for any advice
/RCfun.

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05-08-2005 04:27 AM  12 years agoPost 2
Al Magaloff

rrMaster

12,199 Posts- Enough Time Wasted. See Ya!

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The short answer is, you can't. With the TJs, there is no relationship between the actual ATV number, and the head speed. I found the ATV's to be very different, from model to model. Even models with the same equipment. You need a tach, or you need someone else's governor.

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05-08-2005 11:32 AM  12 years agoPost 3
RCfun

rrApprentice

Denmark

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These measurements where taken from on TJPro installed in one model using one TX (Multiplex Royal Evo 9). Shouldn't it then be possible to generate a graph or table for how the head speed corresponds to different % values in the Tx - just for this model?

/RCfun

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05-08-2005 12:39 PM  12 years agoPost 4
Captain

rrApprentice

New Castle,Indiana

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I have found you really can't check it on the ground. I don't like tieing it down. I agree with Al, I have 2 identical Evo setups and the ATVs are very different. I checked one on the ground just before it would lift off and rpm was 1610. Got it into hover and found it was 1525. Just be sure to have someone help you. Later

Captain

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05-08-2005 02:14 PM  12 years agoPost 5
RCfun

rrApprentice

Denmark

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Ok thanks for both your comments.
I did not tie the heli down. Instead I ran it with a bit of negative pitch and always ready on the controls while someone else did the tach readings.

/RCfun.

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