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Old Jul 05, 2010, 08:49 AM
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HeliEye's Avatar
Stevenage, Hertfordshire
Joined Dec 2007
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Good information on your design & plans ;-)
Just one question... do the arms 'need' to be 20 inches long?
Quads always seem to be much shorter. I understand long arms are likely to be more stable, but was trying to workout if 12" arms was feasible, possibly with improved electronics/gyro's or inertia sensors? for my particular application the overall footprint needs to be smaller (similar to quads).

Any thoughts guy's?

Steve
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Old Jul 05, 2010, 09:15 AM
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Australia, NSW, Yass
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You can make the arms as long or as short as you want, but it comes with a trade off.

A long armed copter will be more stable, but will be less nimble. ( Good for aerial photography or FPV)

A smaller armed copter will be less stable and more nimble. (Good for zipping around)

Mine are 410mm arms (16 inches) and is fine.
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Old Jul 05, 2010, 09:24 AM
Flying on Flux Capacitors
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Edmonton, AB
Joined Apr 2005
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Quote:
Originally Posted by MarcAntonio View Post
Here's my 2 cents:

The throttle should have ample margin for the gyros to have any effect.
If you need too much throttle to carry the cam, then there isn't any left over for the gyros to compensate.

Say for example that you are at 90% throttle and one arm dips and at that point it needs 20% more power to quickly compensate, where is it gonna get it from?
What props are you using?

The other possibility is that with the added weight you are pulling way more AMPS that the battery is capable of giving without voltage sagging.

Do you have a battery monitor that beeps?

Does it beep when this is happening?

If that's the case, a bigger , higher C battery could do the trick.

Thanks Everyone!

I am using 10x4.7SF props which are 1 size under the recommended size for this motor. The batteries are 25C hyperions which have no troubles pumping out much higher currents for my other planes and helis. The lipo monitor stays lit as a solid blue when this happens...double checked with a multimeter and the batteries are defiantly not sagging.



Quote:
Originally Posted by The_Mongrel View Post
This sounds to me like your battery is sagging and your ESCs are cutting out.

Have you reprogrammed your ESCs to LOW cut-off and NiMH setting?
ESC's have been programmed quite a few times to the correct settings. I have even tried advancing and lowering the timing to see if I was loosing sync with the motor. No avail.

Quote:
Originally Posted by micarus View Post
Hi Flipper,
Sounds similare to my problem, mine do that only they go full stop sometimes two at once and drop the tri ' like a stone. I have decided to get some simple esc,s and see if that cures it, the esc,s I am using are Hobby-wing Guard series, don't know if the "guard" bit is the prob' or not , hope you get it sorted , I,v programed my esc,s till i'm blue in the face ,individualy and all together but no luck yet , havn't got a votage monitor on board yet ,! I must get one.
Keep at it Cheers MIKE.
Ahh! I'm glad I'm not dealing with a full throttle problem! I think I've narrowed mine down to something before the ESC's as swapping motors and ESC's makes no difference.


Quote:
Originally Posted by GALENM View Post
I had the same problem , the motors would run fine for a while then one would drop out. Usually with a light click or squawk.

I think the bearings were seizing. So I rigged a 3 in one oil can with a 1.5" hypodermic needle allowing me to reach into the bearings and apply a small drop of oil. That seems to have solved the problem. I may have to repeat this periodically
I double checked the bearings and individual current draw of all motors. They all pull the exact same amperage and run smooth as silk.

The funny bit is the tri has gobs of power! I can comfortable hover right around 1/2 stick and it climbs ballistically near full throttle! I will tri a cameraless flight tonight and see if the weight change makes any difference. The next step after that will be a gyro swap to see if I can recreate the problem on a different motor.

Curt
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Old Jul 05, 2010, 09:37 AM
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Quote:
Originally Posted by Flipper_118 View Post
Thanks Everyone!


ESC's have been programmed quite a few times to the correct settings. I have even tried advancing and lowering the timing to see if I was loosing sync with the motor. No avail.


Curt
Curt,

How have you got the ESCs programmed. Please quote all the programming.

Cheers
-J
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Old Jul 05, 2010, 12:50 PM
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Stevenage, Hertfordshire
Joined Dec 2007
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Quote:
Originally Posted by The_Mongrel View Post
You can make the arms as long or as short as you want, but it comes with a trade off.

A long armed copter will be more stable, but will be less nimble. ( Good for aerial photography or FPV)

A smaller armed copter will be less stable and more nimble. (Good for zipping around)

Mine are 410mm arms (16 inches) and is fine.
Cheers for the reply and insight. 16" is a bit better.

I had a thought, I wonder if mounting the gyro's nearer to props would make it more sensitive and, hopefully more stable with the reduced arm lengths?

I have a GAUI quad here (yet to be assembled) which is the 'ideal' size. It's a pity that diy quads are a lot more tricky, compared to tricopters.

All we need now is someone to design a sneaky quad that 'doesn't' need all the special (read expensive) electronics ;-)

Cheers.... Steve
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Old Jul 05, 2010, 01:19 PM
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Romania, Dolj, Craiova
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Quote:
Originally Posted by HeliEye View Post
Cheers for the reply and insight. 16" is a bit better.

I had a thought, I wonder if mounting the gyro's nearer to props would make it more sensitive and, hopefully more stable with the reduced arm lengths?

I have a GAUI quad here (yet to be assembled) which is the 'ideal' size. It's a pity that diy quads are a lot more tricky, compared to tricopters.

All we need now is someone to design a sneaky quad that 'doesn't' need all the special (read expensive) electronics ;-)

Cheers.... Steve
Placing the gyros farther from center doesn't make them more sensitive, actually will decrease sensitivity, because they are sensible to angular movements more than linear.

What about this low cost 40cm 90 grams quad?
http://mmuennich.de/Deutschland/Mode...Low%20Cost.htm
Isn't it cute? Pair it with the $60 kaptainkuk controller, and you are done.
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Old Jul 05, 2010, 02:08 PM
Flying on Flux Capacitors
Flipper_118's Avatar
Edmonton, AB
Joined Apr 2005
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Quote:
Originally Posted by The_Mongrel View Post
Curt,

How have you got the ESCs programmed. Please quote all the programming.

Cheers
-J
Sure thing...going from memory here,

Brake - Off
Batt Type - Nixx
Cut Off - Soft (either Cutoff or Soft as choices)
Cut Off Voltage - Low
Start Mode - Normal
Timing - Middle
Music/Li-po Cells - N/A
Governor - Off

I believe these are the correct and recommended settings people are using with the SS series ESC's.

Curt
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Old Jul 05, 2010, 03:46 PM
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United States, NV, Silver Springs
Joined Mar 2007
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Prop Failure

The bad: GWS prop had a known stress line at the root of one of the blades, but flew it anyway (I won't be that stupid again). The prop broke at the stress crack at around 150 feet. I was flying my Sony Webbie with video TX for AP.

The good: The onboard Flymentor was able to keep the Tricopter upright all the way to the ground. Landed in a brush pile and received zero damage beyond the original broken prop.

Another good reason to have the flymentor. I now call the Flymentor configured Tricopter the Trimentor.
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Old Jul 05, 2010, 07:26 PM
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Australia, NSW, Yass
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Quote:
Originally Posted by Flipper_118 View Post
Sure thing...going from memory here,

Brake - Off
Batt Type - Nixx
Cut Off - Soft (either Cutoff or Soft as choices)
Cut Off Voltage - Low
Start Mode - Normal
Timing - Middle
Music/Li-po Cells - N/A
Governor - Off

I believe these are the correct and recommended settings people are using with the SS series ESC's.

Curt

Yep - that is good.

Have you opened the Gyros and filled them with foam?
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Old Jul 05, 2010, 10:44 PM
Flying on Flux Capacitors
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Edmonton, AB
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Quote:
Originally Posted by The_Mongrel View Post
Yep - that is good.

Have you opened the Gyros and filled them with foam?
I have not yet done that mod.

Update Report:

I flew the tri again tonight in the exact same configuration as last night. I took off and noticed the usual motor cutout (only the opposite side this time). Seeing that my tail motor was waggin all over the place I reduced the gain on the yaw gyro and flew the rest of the pack without any dropouts. Loaded another fresh pack in and 1-2min into the flight I had the same motor slowing issue leading to a crash (once again on the opposite side as last).
Made the last flight of the day on another fresh pack and had the motor slowing issue again this time on the tail motor!

I've tested my packs tonight and under load they hold there voltages. They also take a full 2100mah to charge when I cycle them on my charger. One thing I did notice was the rock pinging sound the motors make when they fall out of sync. During one power blip I noticed I could hear the motor sound change before I felt the loss of control. I wonder if its possible that my issue is simply the ESC's loosing sync with the motors? I know this is fact at very low throttle settings (I can hear the pings and clicks).

I would love to test this theory but that involves me buying 3 brand names ESC's...

Curt
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Old Jul 05, 2010, 10:49 PM
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The pinging sounds like bad esc to motor connection.
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Old Jul 05, 2010, 11:03 PM
Flying on Flux Capacitors
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Edmonton, AB
Joined Apr 2005
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Quote:
Originally Posted by rcboosted View Post
The pinging sounds like bad esc to motor connection.
That is also a possible cause...but that fact that none of my other ESC's do this has me questioning the integrity of my cheap ESC's. Grrr, my thought process has always been buy cheap buy twice but the success others are having with these units baited me in!

Curt
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Old Jul 06, 2010, 01:34 AM
SSM
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Quote:
Originally Posted by HeliEye View Post
It's a pity that diy quads are a lot more tricky, compared to tricopters.

All we need now is someone to design a sneaky quad that 'doesn't' need all the special (read expensive) electronics ;-)
Steve,

If you have 90 degree mixing on your TX, you can make a Quad simply by making a "tricopter" with 4 arms - see Simple Quad.

They really fly beautifully.

Simon
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Old Jul 06, 2010, 11:34 AM
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Texas
Joined Nov 2006
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I had the same thing going on with mine. I changed out from 72 mhz radio to a 2.4 ghz. Ended the problems completely. 72 just gets interferance and its very predictable. I could hover and know pretty close when it would happen. It would happen on random motors also. Been flying for several months now and haven't had it happen again. Several others have fixed the problem this way also.


Quote:
Originally Posted by Flipper_118 View Post
I am stumped,

I am still having motors give out on me! I relocated my ESC's in order to keep the battery leads the stock length and increased the motor leads. I've current clamped my whole setup and everything is well overrated power system wise. I went out this evening for a test flight and 30secs into a brand new pack the right front motor kicks out...slowly...so I skid in for a landing and before the motors even came to a stop I lift off again. Repeat.

Finally I decided to see if its possible to correct with massive left stick. I climbed up about 10feet and waited in a hover for the drop out. As soon as I started listing right I nailed in full left stick but down she still came.

I am totally stumped now. I still maintain control so I know its not receiver related. ESC programming is correct. ESC's are cool, motors are cool...the only thing I can possibly think of is my gyro for the front right is wigging out on me.

Any ideas?

Curt
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Old Jul 06, 2010, 12:10 PM
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Bullhead, AZ.
Joined Oct 2009
35 Posts
Man! this thread gets longer and longer

My new Tricopter frame just showed up a 1/2 hour ago. I only had to put on the landing gear and straighten the booms out to their positions. This thing is nice looking and I can't wait to get my parts on it. Nice yaw mount also. My frame with skids weighs only 294 grams.

Now I need to go back and start reading where I left off a couple of weeks ago.
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