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Author Topic: prop brake?  (Read 606 times)

Offline andreas johansson

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prop brake?
« on: July 30, 2009, 12:04:28 PM »
Hi all!

Hmmm, I´m start to feel that I might start new topics a bit too often. Maybe I should start a thread called "Andreas Questions" instead?  ;D
This time I have a question regarding the prop brake, how is it supposed to work? My brake setting is setup on full (100%) brake, but the prop are freewheeling at very slow speed during the landing lap and I suppose that it must be still?

Andreas

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Offline Mark Scarborough

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Re: prop brake?
« Reply #1 on: July 30, 2009, 04:06:45 PM »
what esc are you using? and what version of software is loaded in it. the newer version of the CC software enabled this with govenor , prior to that you could not have both.
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Offline andreas johansson

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Re: prop brake?
« Reply #2 on: July 30, 2009, 04:25:17 PM »
Hi Mark

I'm using a CC Phoenix 35 with firmware 3.130 (latest). I did some bench testing and the motor brakes but it seems like the braking power isn't enough to keep the prop stationary during the landing. The prop is turning very slowly so its definitely not under power, you can clearly see the two blades.

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Kim Doherty

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Re: prop brake?
« Reply #3 on: July 30, 2009, 05:12:08 PM »
Andreas,

The rule requires that the prop come close enough to a full stop that it is easily determined that the motor is no longer supplying power to the model.

The energy to stop the prop comes from the running motor. Once the motor has stopped there is no more energy to be used to keep the prop stationery. Thus the slowly windmilling prop.

Higher cogging motors may bring the prop to a complete stop. I would not base a motor choice decision on this factor alone.

This is how it should be.

Kim.

Offline andreas johansson

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Re: prop brake?
« Reply #4 on: July 31, 2009, 12:46:36 AM »
Hi Kim

Ok, then I will not put more effort into trying to get the prop completely stationary.  :)

Andreas
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Online Peter Germann

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Re: prop brake?
« Reply #5 on: July 31, 2009, 04:38:30 AM »
Hi Andreas

As I see it, you are safe as is, because on pages 31/32 the 2009 FAI Sporting Code describes the landing manoeuvre as fiollows:

4.2.15.17. Landing manoeuvre
Recommended entry procedure: from normal upright level flight at a height of 1.5 metres.

a) Start of manoeuvre: as the model aircraft leaves the height of 1.5 metres, plus/minus 30 cm, and with the motor/s and propeller/s stopped.

b) The descent segment: the model aircraft should fly for 1 full gliding lap with the motor/s and propeller/s stopped, measured from the start of the descent at the 1.5 metres plus/minus 30 cm height, until the point of touchdown. The rate of descent should remain constant throughout this whole gliding lap, from the moment that it leaves the 1.5 metres height until the moment that it touches down. The touch down itself should be smooth and either a "2 point" or a "3 point" touch down shall be judged as being equally correct.

Note: For the purpose of this rule, the word “stopped” describes a situation where the blades of the propeller(s) are actually at a standstill or are rotating so slowly that the individual blades can clearly be seen by an observer.

c) End of manoeuvre: when the model aircraft comes to a complete stop after touching down at the
end of the ground roll which is clearly in a forwards direction and in line with its normal flight
motion. The length of the ground roll shall not exceed one lap.

----------

Best regards
Peter Germann

Offline andreas johansson

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Re: prop brake?
« Reply #6 on: July 31, 2009, 05:55:48 AM »
Hi Peter

Thanks for clearing that up.  :)

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Offline Dean Pappas

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Re: prop brake?
« Reply #7 on: July 31, 2009, 06:18:51 PM »
Hi All,
More importantly ... Thanks Peter for helping to define the rule sensibly!

Regards,
Dean P.
Dean Pappas


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