Depron Ziroli Viggen - Page 3 - RC Groups
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Feb 02, 2012, 07:42 PM
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Are there any small diameter 3 or 4 blade props that will hold up at 38000 rpm?
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Feb 03, 2012, 12:23 AM
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LuvEvolution7's Avatar
highly unlikely. after saying that, larger, cut down props will likely survive at these RPM's because there will be more meat at the root to handle the load. expect bigger loads on the motor though because of larger angle of attack of the blades.
Feb 03, 2012, 07:51 AM
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let's say you got 3500kv motor ods of it ever reaching 3800rpm is un likely under load. use amp meter to ck. only way to ck rpm is with rpm gage not motor spec.
Feb 03, 2012, 08:36 AM
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PS battery C rating also
Feb 03, 2012, 10:11 AM
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I know from flying the stinger and rifle speed 400 planes the 2 blade apc will hold up no problem. These props will also load the motor, speed control and battery in a predictable way. As long as these are producing suitable thrust, I think I will focus my attention here. Will report on results. Thank you all for the input!
Feb 07, 2012, 05:31 PM
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Motor is wired. All I lack is one pushrod. I will try and fly tomorrow if the weather is ok. Final stats for the maiden:

All up Weight with 2200 mah pack is 1lb 9oz.
Wing loading is 9.4 oz/sq ft.
The motor is pulling 29-30 amps and 300 watts with the APC 4.1 prop.
Approx 200 watts/lb
The canard is fixed for the maiden

Potential problems I see:

It pulls with authority, but the thrust is nowhere near 1:1. Thrust was measued at 1 pound for a .67 thrust to weight ratio.
I am using the cg off of the original Zirolli plans. Who knows if this is optimal?
Control throw is off the original Zirolli plans. He used separate surfaces for elevator and aileron. I am using elevons with 40% differential and 30% expo dual rated to 80%. Will it work?
The thrust line is high. There is a significant tendency to pitch down with the power on. I feel a prog mix coming on! I think this will be the biggest challenge to overcome.

Wish me luck. I will try and get someone to video for me.
Last edited by flyingfitz737; Feb 08, 2012 at 01:45 AM. Reason: Measured Thrust Added
Feb 08, 2012, 07:01 AM
EDF rules... :)
AirX's Avatar
Good luck.

Eric B.
Feb 08, 2012, 04:35 PM
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Success! Stay tuned for video.
Feb 08, 2012, 05:38 PM
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Janusz Jawien's Avatar
Congrads! Tell us more!
Feb 08, 2012, 05:49 PM
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Feb 08, 2012, 06:17 PM
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Depron Ziroli Viggen (3 min 51 sec)
Feb 08, 2012, 06:27 PM
Need 4 Speed!
pdawg's Avatar
Well done! You guys took a very nice methodical approach! Definitely flew better with each flight! Are you planning to boost the performance?
Latest blog entry: original Y/A F-18 Kit
Feb 08, 2012, 06:47 PM
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Thanks. The biggest performance killer is the pitching moment from the thrust line being above the vertical cg. It takes a ton of lift to overcome the pitching moment. When the power is pulled it floats like a feather. I plan on moving the battery up as high as possible to help control this unwanted moment. We tested it statically (sp?) and it does make a difference. Once that is optimized as much as it can be, I plan on making the canard functional for pitch. A little prog mix to cancel the remaining moment and it should be reliable throughout the flight regime. I have decided not to make the rudder functional or include the retracts. This will be a hand launch, outdoor-only airplane.
Feb 08, 2012, 07:42 PM
ooooh yeah
Frenche's Avatar
Congrats! It looked great in the air. I swear I have those plans laying around here somewhere....
Feb 08, 2012, 09:55 PM
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Janusz Jawien's Avatar
Now you have "deliciuos" looking well flying airframe to play with adding the flying canards etc. Really nice low key project!

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