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Old Dec 27, 2012, 01:59 AM
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Scotland
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[QUOTE=Golikov;23621083For example, some known to me propellers have a maximum efficiency at the blade angle of attack of about 6 degrees. And to increase the angle of attack to 9 degrees, prop does not stall. But does accelerate just less effective. You spend more energy. In order to achieve the same result on the speed and altitude.
[/QUOTE]

how big is the difference, say from 6 degrees optimum to 4 degrees on one side and 9 degrees on the other?
A long time ago I ran the RFM 15x16 through Martin Hepperle's program and indeed the efficiency curve was very peaked, falling of rapidly from a maximum of 80%.
This was a Hannes Delago design I believe, may be wrong. It was extended by Rudi to the RFM 16x17 slim which can be very effective, but only in certain conditions. But I forget the exact efficiency curve.

Both you and Joe are right, it is the rpm v. forward speed that matters, but the thing we can change is the controller PWM ratio, hence the power, hence the rpm. The rpm could be controlled, like in helicopter governor mode, but this is probably beyond the processing power capability of the ATMega and 8051F processors used in today's controllers at F5B rpms.
Now if Steve's new controller above uses an ARM Cortex controller then we are talking business!
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Old Dec 27, 2012, 11:38 AM
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United States, CA, San Diego
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Quote:
Originally Posted by George Shering View Post
Now if Steve's new controller above uses an ARM Cortex controller then we are talking business!
While it has some interesting features ---- a ARM controller is not one of them

It does have a dedicated line which can be used as a gain control for a RPM governor or that line can provide realtime RPM information. Other features will be added as interest requires.

One nice improvement to the new controller is the option to over write the data log when it fills up--now you can always have the last flight recorded.


Steve Neu
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Old Jan 06, 2013, 08:30 PM
Battery Puffer
Orange, California, United States
Joined Nov 2001
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I flew the enigma again with a lot better flight this time. I changed the throttle response from 10 to 5 and it made a big difference. I was able to do 10 climbs and get everything working and setup right. I may move up a little on the response to maybe 6 or 7 to see how I like it untill I get a proper radio to do ramps. I have a quetion for Steve or Georgi. Can I replace my 18 x 21 blades with the new 18 x 23 blades with out buying a new spinner?

Mark
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Old Jan 06, 2013, 10:30 PM
2012 NZ Speedcup - 231 MPH
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New Zealand, Tasman, Richmond
Joined Mar 2006
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Anyone care to tell me how I can achieve a ramp with my Futaba 9C and 160 HV2? Not for F5B, but speedcup style flying where some kind of ramp is necessary to prevent my setup melting in the first 1-2 seconds...
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Old Jan 07, 2013, 03:08 AM
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MarkF: no, you need to buy a complete prop.
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Old Jan 07, 2013, 07:34 AM
Battery Puffer
Orange, California, United States
Joined Nov 2001
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Thanks Gerben, I only ask because I havn't seen it available in 38mm and because I'm only pulling 159 amps. Aern't you guys pulling closer to 200 amps? My battery and motor were only warm after my flight and all though the speed looked good it didn't look as good as you guys are doing.

Mark
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Old Jan 07, 2013, 01:52 PM
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Hi Mark,

On my WC setup I was at about 5.3kw's, that's pretty close to what you're seeing.
You get used to the speed very quickly

IGerben
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Old Jan 07, 2013, 08:30 PM
Battery Puffer
Orange, California, United States
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The bystanders thought my plane was crazy fast and I thought yea not bad.

Mark
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Old Jan 07, 2013, 08:32 PM
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United States, CA, San Diego
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The bystanders thought my plane was crazy fast and I thought yea not bad.

Mark
You could come down and fly with us sometime and get a first hand idea of the setups that are in use. We are usually out on Sunday afternoons at the SEFSD field.


Steve
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Old Jan 07, 2013, 08:36 PM
Battery Puffer
Orange, California, United States
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Well I guess not this Sunday since the AMA show is this weekend but I might be able to the following weekend. I will double check with you guys when the time comes to make sure your going to be there.

Mark
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Old Jan 29, 2013, 05:00 PM
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Winterthur, Switzerland
Joined Aug 2003
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Limiters?

Hello all,


as a side question related to 10s powertrains, what limiters are used or available? Is a SM Unilog setup required or are Neu or eflight or any other manufacturer coming out with their custom-made limiters? I see currently available limiters are good up to 6s only.


Looking forward to getting into F5B,
Cheers, Andy
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