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Old Feb 21, 2010, 06:20 AM
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The_Mongrel's Avatar
Australia, NSW, Yass
Joined Dec 2007
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Originally Posted by Trnquill View Post
Did my tricopter maiden today. It has HK401 gyros and 750 motors. Managed to do two batteries in lovely -17 °C & 10m/s winter weather.

I could not get it to fly correctly. The motors were pulsating all the time. First I had the gyro delays at max, but after first battery I pulled them back to 50% (potentiometer at half way). This helped a little. The gyros were in digital mode.

It was far from stable. I would say way more unstable than a 450 heli! I did play with gyro gains and ended up somewhere around 20% on the radio (that's 60% gain in rate mode). I bumped up expo all the time and went as high as 50%. This was a bit too much so I'll try around 40% next time. I also have to move the battery somewhere else. The tri is very nose heavy if I mount the battery inside my frame like it is now, as far back it goes before hitting wires & ESCs & what not inside the frame. I think I'll just hang it under the frame so I can adjust the position more easily.

I had to stop when one of the motors froze up. We have thick (15-30cm) coat of light snow here at Finland and the tri spent quite long periods of time flying inside a cloud of snow. Too bad I don't have a video... My camcorder decided to forget how to make a proper exposure showing just plain white screen...

Any ideas on why the motors were pulsating, though?
Dont run the Gyros in Digital mode. There is no need. I have mine in standard and my Tri is VERY stable. A lot of others don't run Digital mode either.

With the Gain on the Gyro - I don't use the pot on the gyro itself. If you are using gain on the radio, the pot will do nothing anyway.
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Old Feb 21, 2010, 08:07 AM
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Joined Jun 2009
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Originally Posted by The_Mongrel View Post
Dont run the Gyros in Digital mode. There is no need. I have mine in standard and my Tri is VERY stable. A lot of others don't run Digital mode either.

With the Gain on the Gyro - I don't use the pot on the gyro itself. If you are using gain on the radio, the pot will do nothing anyway.
Someone in this thread said HK401's do better in digital mode. But I'll try in analog!

The HK401's do not have a gain pot on them. They have delay and limit. I had the delay all the way up at first, then I dropped it to 50%. I'll try 0% in a minute and see what that does. The limit is at 100% and I guess that's the way it should be.
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Old Feb 21, 2010, 08:35 AM
A man with too many toys
United States
Joined Feb 2001
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Quote:
Originally Posted by The_Mongrel View Post
Dont run the Gyros in Digital mode. There is no need. I have mine in standard and my Tri is VERY stable. A lot of others don't run Digital mode either.

With the Gain on the Gyro - I don't use the pot on the gyro itself. If you are using gain on the radio, the pot will do nothing anyway.
I can run quite a bit more gain if I use the digital mode (about 5%). That will depend on the ESC motor and prop. The only problems I have heard about is using the digital mode with some HK brand ESC’s. I use Turnigy ESC’s and they have always worked perfectly in the digital mode.

I always run the delay at 0. I tried other settings but did not see any difference.


I have also found that frame stiffness makes a difference in the max gain you can run. Stiffer booms and a more rigid frame allow more gain and better stability.

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Old Feb 21, 2010, 10:21 AM
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United States, CA, Los Angeles
Joined Aug 2009
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Originally Posted by Trnquill View Post

I could not get it to fly correctly. The motors were pulsating all the time. First I had the gyro delays at max, but after first battery I pulled them back to 50% (potentiometer at half way). This helped a little. The gyros were in digital mode.

Any ideas on why the motors were pulsating, though?
My present understanding is, when the Gyro is in Digital Mode, you need to set the Delay to zero.
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Old Feb 21, 2010, 11:06 AM
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Kungshatt
Joined Mar 2008
200 Posts
Quote:
Originally Posted by Trnquill View Post
Did my tricopter maiden today. It has HK401 gyros and 750 motors. Managed to do two batteries in lovely -17 °C & 10m/s winter weather.

I could not get it to fly correctly. The motors were pulsating all the time. First I had the gyro delays at max, but after first battery I pulled them back to 50% (potentiometer at half way). This helped a little. The gyros were in digital mode.

It was far from stable. I would say way more unstable than a 450 heli! I did play with gyro gains and ended up somewhere around 20% on the radio (that's 60% gain in rate mode). I bumped up expo all the time and went as high as 50%. This was a bit too much so I'll try around 40% next time. I also have to move the battery somewhere else. The tri is very nose heavy if I mount the battery inside my frame like it is now, as far back it goes before hitting wires & ESCs & what not inside the frame. I think I'll just hang it under the frame so I can adjust the position more easily.

I had to stop when one of the motors froze up. We have thick (15-30cm) coat of light snow here at Finland and the tri spent quite long periods of time flying inside a cloud of snow. Too bad I don't have a video... My camcorder decided to forget how to make a proper exposure showing just plain white screen...

Any ideas on why the motors were pulsating, though?
Moi, I too have tried to fly in the cold. Today it was -12C but I decided not to fly because I cant trust the gyro beneath -5C (according to the spec.). But over -5C it flies great. Maybe the gyro can make that stange motor behaviour??
I also isolated the battery pack to gain more power. Without the isolation the flight time vere about 4min...
I long for the summer!!!
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Old Feb 21, 2010, 11:45 AM
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Edmonton, Alberta, Canada
Joined Jun 2004
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I flew in temperatures lower than -5C and the Gyros worked OK. I would not worry about flying in lower temperatures as long as you let the Tri sit outside for a few minutes before the flight so that the gyros can adjust to the flight temperature.
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Old Feb 21, 2010, 01:12 PM
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Originally Posted by bofred View Post
Moi, I too have tried to fly in the cold. Today it was -12C but I decided not to fly because I cant trust the gyro beneath -5C (according to the spec.). But over -5C it flies great. Maybe the gyro can make that stange motor behaviour??
I also isolated the battery pack to gain more power. Without the isolation the flight time vere about 4min...
I long for the summer!!!
Hej, I adjusted my CoG (which was way off), reduced the gyro delay and switched them to analog. And lo and behold, it flew just great! Not much pulsing anymore and very controllable flight. Instead of uncontrollable 10 second hops I was able to fly circles and eights five minutes (full battery) without a slightest problem.

Five minute flight in -16C equals 1500mAh of juice drawn from the batteries. This is 50% of my 3000mAh Turnigy pack so I can push two more minutes of flying fun! I walked to my flying spot (about 5 minute walk) and had no problems with the HK401 gyros.

I still need to adjust tail gain & delay to make it behave more accurately. It's OK at the moment but could be way more solid.

I added a few pics of the completed system at the end of the series: http://fotoni.org/ilmasta/tricopter/

reverendrichie: I'm not sure if gyro mode (digital or analog) has anything to do with delay. After all, delay is there to compensate response time of the tail driving system (servo, linkages, etc.). When using digital servos the delay needs to be turned all the way down, that's for sure!
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Old Feb 21, 2010, 01:13 PM
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Kungshatt
Joined Mar 2008
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Originally Posted by Talontsi96 View Post
I flew in temperatures lower than -5C and the Gyros worked OK. I would not worry about flying in lower temperatures as long as you let the Tri sit outside for a few minutes before the flight so that the gyros can adjust to the flight temperature.
That is good news!! Often when the sun is shining the temperature drops down under -10C and it would be great to have some shiny snow photos from the air :-)
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Old Feb 21, 2010, 01:29 PM
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Kungshatt
Joined Mar 2008
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Quote:
Originally Posted by Trnquill View Post
Hej, I adjusted my CoG (which was way off), reduced the gyro delay and switched them to analog. And lo and behold, it flew just great! Not much pulsing anymore and very controllable flight. Instead of uncontrollable 10 second hops I was able to fly circles and eights five minutes (full battery) without a slightest problem.

Five minute flight in -16C equals 1500mAh of juice drawn from the batteries. This is 50% of my 3000mAh Turnigy pack so I can push two more minutes of flying fun! I walked to my flying spot (about 5 minute walk) and had no problems with the HK401 gyros.

I still need to adjust tail gain & delay to make it behave more accurately. It's OK at the moment but could be way more solid.

I added a few pics of the completed system at the end of the series: http://fotoni.org/ilmasta/tricopter/

reverendrichie: I'm not sure if gyro mode (digital or analog) has anything to do with delay. After all, delay is there to compensate response time of the tail driving system (servo, linkages, etc.). When using digital servos the delay needs to be turned all the way down, that's for sure!
Terve, That is a really nice build!!
Maybe I was too afraid to fly in cold weather. Next sunny day I will make a test. I dont want to drop it because we have so much snow so it would be hard to find it ;-)

Soon hobbycity will ship me a 4Ah battery and then I can fly until my hands fall of...
I have a build log of my build here: http://www.rcgroups.com/forums/member.php?u=200107
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Old Feb 21, 2010, 02:44 PM
making big holes in the sky..
Scandinavia
Joined Aug 2009
314 Posts
Quote:
Originally Posted by Trnquill View Post
Hej, I adjusted my CoG (which was way off), reduced the gyro delay and switched them to analog. And lo and behold, it flew just great! Not much pulsing anymore and very controllable flight. Instead of uncontrollable 10 second hops I was able to fly circles and eights five minutes (full battery) without a slightest problem.

Five minute flight in -16C equals 1500mAh of juice drawn from the batteries. This is 50% of my 3000mAh Turnigy pack so I can push two more minutes of flying fun! I walked to my flying spot (about 5 minute walk) and had no problems with the HK401 gyros.

I still need to adjust tail gain & delay to make it behave more accurately. It's OK at the moment but could be way more solid.

I added a few pics of the completed system at the end of the series: http://fotoni.org/ilmasta/tricopter/

reverendrichie: I'm not sure if gyro mode (digital or analog) has anything to do with delay. After all, delay is there to compensate response time of the tail driving system (servo, linkages, etc.). When using digital servos the delay needs to be turned all the way down, that's for sure!
Glad to hear good news from the land of the thousand lakes....
And I must say that you bulind looks nice...almost sexy

I run my gyros for the ESCs on digital with 0 delay and in analog for the rudder-servo with 50% delay and about 60% gain in both rated and HH mode.
I have it an channel 8 on the RX so i can switch from rated to HH..
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Old Feb 21, 2010, 03:25 PM
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quailbird's Avatar
Rich Hill Missouri 64779
Joined Nov 2003
8,381 Posts
I have a question. What size is the shaft of the 750 motors! On the Hobby King page it says 4M. What does that mean? It doesn't say 4mm, it says 4M. I cannot believe the shafts on those little motors are 4mm. Could someone let me know. I would like to buy some prop savers. Thanks guys!
Carl
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Old Feb 21, 2010, 03:34 PM
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San Jose CA.
Joined Jun 2006
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Hi Carl,
The shaft of the 750 is indeed 4mm.

Tbee
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Old Feb 21, 2010, 03:49 PM
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Rich Hill Missouri 64779
Joined Nov 2003
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Wow! Thanks! I would not have guessed that in a million years! The pictures makes it look like shafts on a BP21. I do appreciate the comeback.
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Old Feb 21, 2010, 04:08 PM
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signguy's Avatar
Swansea, Massachusetts
Joined Dec 2004
2,088 Posts
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Originally Posted by quailbird View Post
Wow! Thanks! I would not have guessed that in a million years! The pictures makes it look like shafts on a BP21. I do appreciate the comeback.
Wait till you get those DT750's Quail. They are much larger than you think! The 4mm nuts for the shaft ( there are none in the dt750 boxes) are available at lowes and home depot. I just use std nuts, but you could use nylock nuts too. You will have to drill out the props a bit.

See Ya
Bob D
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Old Feb 21, 2010, 04:24 PM
Have a nice day! Kristjan
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Slovenia, Novo mesto, Šentjernej
Joined Jan 2006
808 Posts
Today I had first crash.

tricopter 3rd flight (4 min 8 sec)
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