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Old Oct 21, 2010, 11:52 AM
Looptastic!
sp00fman's Avatar
Enschede, Netherlands
Joined Nov 2009
2,248 Posts
Lol. i diddnt want to restart the discussion about the "fakeness" of the video again. There is a huge topic about that already on helifeak. Conclusion was it isn't fake and people had to take their words back. One thing you can't easily fake is the way the blades look to be bend by the scanline frequency of the camera.....
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Old Oct 21, 2010, 12:26 PM
Things that do fly
Magic k2's Avatar
In my house ;-) The uk
Joined Dec 2008
2,709 Posts
I take it all back ,,he is fkn awsome ,,i was looking at another video of him and at the end he walks forward and he looks like he is moving strange and jerky just like the first video,,,its the junk camera that he has,,it has low frame rate or the upload conversion is lowering the frame rate and making it all jerky and then looks speeded up.
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Old Oct 21, 2010, 12:45 PM
Looptastic!
sp00fman's Avatar
Enschede, Netherlands
Joined Nov 2009
2,248 Posts
Many years ago i found a video on the interwebs from a small ccpm doing 3d. i watched it amazed about 10 times and concluded the heli was computer animated or flown by a computer.
the video was 200dpi or so and full of compression errors. no details to be found on there.
Still almost cant believe I now own a heli that can do all that ...
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Old Oct 21, 2010, 01:51 PM
Fix, Fix, Fly, Fix, Fix, Fly
mountainsax's Avatar
Colorado
Joined Apr 2009
635 Posts
Does a 6 minute flight time, hovering only, make sense for a 4000kv motor, 13t pinion, and 2200/20c lipo?
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Old Oct 21, 2010, 02:03 PM
Resident Skeptican
Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
4,323 Posts
Depends on your throttle curve. According to Dark Horse's advanced head speed calculator you should be able to get 6 minutes of hovering with that combo if your throttle is set at 79% at hover with 1.86* pitch. That would give you about a 3750 rpm real world head speed though?
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Old Oct 21, 2010, 02:13 PM
Fix, Fix, Fly, Fix, Fix, Fly
mountainsax's Avatar
Colorado
Joined Apr 2009
635 Posts
Throttle curve is roughly 80% at hover, don't know the pitch (curve is linear from mid stick to full). I seriously doubt that the head speed is anywhere near 3750rpm!

I was just curious as I got about 6 min (maybe a little less) of hovering, with a couple landings, before the heli powered down again. I was trying to program the ESC but obviously was not doing something right. I was thinking it may just be that the power is getting down to some lower limit and triggering things to shutdown. Just a theory...
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Old Oct 21, 2010, 02:33 PM
master of the universe
captaingeek's Avatar
USA, CA, Novato
Joined Jul 2008
3,077 Posts
6 minutes may be normal. if your pitch is too high it will kill your battery.
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Old Oct 21, 2010, 02:33 PM
Resident Skeptican
Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
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Why would you doubt it's anywhere near 3750 RPM?

12.6v * 4000kv * 85% efficiency = 42840 rpm on the motor. Divided by 11.54 (your gear ratio) gives you 3700 head speed at WOT. Your motor could be more or less efficient. Your head speed would actually be a bit lower since you're not hovering at WOT, but it's going to be pretty high regardless.

Edit:

Also forgot to add that that's assuming they fudged the numbers and decided on the KV rating based on 100% efficiency.

If they didn't fudge their numbers then:

12.6v * 4000kv = 50400rpm. Divided by 11.54 = 4367rpm head speed at WOT!
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Old Oct 21, 2010, 03:38 PM
Fix, Fix, Fly, Fix, Fix, Fly
mountainsax's Avatar
Colorado
Joined Apr 2009
635 Posts
That is higher than I expected! I was getting set to install some wooden blades (replacing the stock plastic), should I be concerned with the head speed? I have an 11t pinion on the way, should I wait for that to install the woodies?

thanks again for the help Barak!!
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Old Oct 21, 2010, 04:33 PM
Resident Skeptican
Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
4,323 Posts
I tried a 4000kv with 11t pinion and found it to have a bit less power at the same throttle than a 3600kv with 12t pinion, but it was acceptable for sport flying around the yard.

If you're running the standard 2200mah 20c/25c batteries the 11t pinions will make your batteries hate you much less.
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Old Oct 21, 2010, 04:35 PM
Resident Skeptican
Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
4,323 Posts
Double post
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Old Oct 21, 2010, 05:48 PM
Things that do fly
Magic k2's Avatar
In my house ;-) The uk
Joined Dec 2008
2,709 Posts
Give him that link to helihead speed thingy for the computer,i tred it out when you posted it and its very cool,,for you guys that havnt seen it ,its a program that listens to the noise from your blades and tells you the head spead of your heli,very cool and handy,,its like free test equipement
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Old Oct 21, 2010, 06:06 PM
Resident Skeptican
Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
4,323 Posts
http://www.digitizeit.de/heli/
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Old Oct 21, 2010, 06:25 PM
Put a bigger motor on it!
gtfreeflyer's Avatar
Costa Mesa, CA
Joined Feb 2007
1,395 Posts
Quote:
Originally Posted by Barak1001 View Post
Why would you doubt it's anywhere near 3750 RPM?

12.6v * 4000kv * 85% efficiency = 42840 rpm on the motor. Divided by 11.54 (your gear ratio) gives you 3700 head speed at WOT. Your motor could be more or less efficient. Your head speed would actually be a bit lower since you're not hovering at WOT, but it's going to be pretty high regardless.

Edit:

Also forgot to add that that's assuming they fudged the numbers and decided on the KV rating based on 100% efficiency.

If they didn't fudge their numbers then:

12.6v * 4000kv = 50400rpm. Divided by 11.54 = 4367rpm head speed at WOT!
Which LiPo are you using that has zero voltage drop under load, and maintains a full charge after spool up and lift off? I want one of those!
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Old Oct 21, 2010, 06:26 PM
Put a bigger motor on it!
gtfreeflyer's Avatar
Costa Mesa, CA
Joined Feb 2007
1,395 Posts
Quote:
Originally Posted by sandos View Post
Users of Spartan Quark, do you use the 3mm foam pad they say you should use? I read that it really likes hard foam pads?
I did it exactly as shown in the manual, with the hard plate sandwiched between the thicker and thinner foam pads, and the gyro sitting on the thinner foam pad. Flies rock solid.
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