Sep 01, 2010, 02:18 AM
That tree again!!!!
Germantown, MD, US
Joined Sep 2004
6,645 Posts
Quote:
 Originally Posted by SSM There seem to be two different schools of thought on this point: 1. It doesn't matter at all where on the frame the gyros are located. Gyros only detect angular changes and the angular changes are identical everywhere on the frame. See FlipFlop's tri-copter for an example of a tricopter with its gyros placed far off centre but which flies beautifully. 2. As thanhTran says - gyros should be central, so the axis of the gyros are on (or close to) the roll/pitch/yaw axes of the copter. I'm a type 1 kind of person myself. Simon
EDIT: I draw a picture and see that the rotation speed is the same no matter how close or how far it is from the center of the rotation. So gyro should be fine to be put away from center . Great to know this.
Last edited by thanhTran; Sep 01, 2010 at 01:12 PM.
Sep 01, 2010, 02:29 AM
Voluntary Assumption of Risk
Australia, VIC, Canterbury
Joined Nov 2003
1,266 Posts
Quote:
 Originally Posted by thanhTran If we look at a rotating disc and put a nail at the center of the disc. This nail spins. Put a nail further away from the center this nail don't spin any more: it moves.
Maybe you should actually try that. I just have.

You'll find that for each one (1) turn of your rotating disc, the nail in the center makes one (1) turn. And the nail that's away from the center makes .... well, it also makes one (1) turn.

So, both nails (or both gyros, if you like) "feel" the same amount of rotation, whether they're at the center, or out and away from the center.

Simon
 Sep 01, 2010, 02:39 AM Registered User Joined Jul 2009 1,456 Posts In that case, then moving gyros futher away from an axis wouldn't reduce sensitivity or allow for increasing gain, but would likley increase the noise vs signal ratio due to more linear vs angular motion. A few inches one way or another might not make any significant difference though.
Sep 01, 2010, 02:40 AM
Registered User
United Kingdom
Joined Nov 2008
2,035 Posts
Quote:
 Originally Posted by thanhTran Interesting. I think the further away from the rotation axis, the gyro is less effective. If we look at a rotating disc and put a nail at the center of the disc. This nail spins. Put a nail further away from the center this nail don't spin any more: it moves. The further away from the center, the faster it moves, and I believe it spins slower. Gyro works with angular rotation around its axis so it's best to put at the center. I'm interested to know if the rotation of the gyro is still the same when it's far away from the center of the CG of the heli though.
Interesting discussion.

A gyro at CoG experiences only angular motion, whereas if displaced, experiences both angular and a displacement movement (theres probably better words for this).

This ofcourse assumes that the model is in a fixed position, which ofcourse it isn't since it's inevitably moving around in 3 axis.

So I'm tempted to say it probably doesn't matter, but this is just my opinion.
 Sep 01, 2010, 02:44 AM Friend is a 4 letter word... 3rd stone from the sun Joined May 2007 2,679 Posts A gyro measures angular velocity. Angular velocity is the same at the end of the arm as at the center of copter. Bottom line: Gyros can be mounted anywhere you please as long as they are parallel to the axis it controls Latest blog entry: AutoQuad hexacopter with Alexmos...
Sep 01, 2010, 02:56 AM
manuLRK
Belgium
Joined Sep 2004
1,535 Posts
Quote:
 Originally Posted by SSM There seem to be two different schools of thought on this point: 1. It doesn't matter at all where on the frame the gyros are located. Gyros only detect angular changes and the angular changes are identical everywhere on the frame. See FlipFlop's tri-copter for an example of a tricopter with its gyros placed far off centre but which flies beautifully. 2. As thanhTran says - gyros should be central, so the axis of the gyros are on (or close to) the roll/pitch/yaw axes of the copter. I'm a type 1 kind of person myself. Simon
It doesn't matter for angle changes.
Look at the rc-heli gyro's, they are all off center!

manuLRK
Sep 01, 2010, 06:57 AM
Registered User
Joined Aug 2009
1,726 Posts
push it to the limit and through corn

 kk quadrocopter - devil inside (2 min 52 sec)
Sep 01, 2010, 07:24 AM
Germany, NRW, Dusseldorf
Joined Jun 2010
5,722 Posts
Quote:
 Originally Posted by warthox push it to the limit and through corn
LOL! Did you offer the farmers some help for the harvesting?
 Sep 01, 2010, 08:04 AM Registered User Manchester Joined Jul 2008 464 Posts Hi Guys, I had an amazing flight this morning getting some video. I flew at a location where I have always wanted to fly.. it is just such a great setting. I think this location was the final inspiration I need to convince me i needed a multicopter. This is the local parish in the background with a War memorial and gardens in the foreground. How amazing to fly in this location whilst remembering those that gave their lives for their country... just special... Hope you like it... Charl Here is my parts list, KK Controller : http://www.kkmulticopter.com/ Motors : XYH 28-30B 750Kv 10A Brushless Outrunner http://www.giantcod.co.uk/2830b-750k...-p-404451.html Props : EPP1045 / 5mm https://www.mikrocontroller.com/inde...9c02cde3e3873a ESC's : TURNIGY Plush 18amp Speed Controller http://www.hobbycity.com/hobbyking/s...idProduct=4312 Gyro's : Hobby King 401B Gyro http://www.hobbycity.com/hobbyking/s...dProduct=10113 Batt : 2 X 3S1P 2200mAh RX : JR R700 PPM 35Mhz Motor to Motor distance : 80cm My Photo Thread... http://www.axlb16.dsl.pipex.com/My%2...ter/index.html Last edited by cvandenb; Sep 01, 2010 at 08:46 AM.
Sep 01, 2010, 08:23 AM
United States, TX, San Antonio
Joined Feb 2007
15,139 Posts
Marcus,
More absolutely great flying and an excellent and entertaining video!
What version of board were or are you using now?
Thanks and Cheers,
Jim

@Cavdenb
Also nice video!
Cheers,
Jim

Quote:
 Originally Posted by warthox push it to the limit and through corn
Quote:
 Originally Posted by cvandenb Hi Guys, I had an amazing flight this morning getting some video. ...Hope you like it... My Photo Thread... http://www.axlb16.dsl.pipex.com/My%2...ter/index.html
Last edited by jesolins; Sep 01, 2010 at 08:37 AM.
Sep 01, 2010, 08:46 AM
The tattoo guy
USA, MN, St Paul
Joined Jun 2009
653 Posts
Quote:
 Just ordered my board today.

Greg,
What board did you order?
I got mine from the classifieds from the KK site.
Eric sold it to me.
Let me know.
thanks
Grease
Sep 01, 2010, 09:56 AM
"Let's put a camera on that.."
Twin Cities, MN
Joined Feb 2010
1,063 Posts
Most retail gyro instructions ask to have the units placed as close to the axis it's intended to be watching, in my experience. It makes sense to me, but I'm intrigued that they would work just as well elsewhere..

Quote:
 Originally Posted by SSM There seem to be two different schools of thought on this point: 1. It doesn't matter at all where on the frame the gyros are located. Gyros only detect angular changes and the angular changes are identical everywhere on the frame. See FlipFlop's tri-copter for an example of a tricopter with its gyros placed far off centre but which flies beautifully. 2. As thanhTran says - gyros should be central, so the axis of the gyros are on (or close to) the roll/pitch/yaw axes of the copter. I'm a type 1 kind of person myself. Simon
Sep 01, 2010, 10:04 AM
"Let's put a camera on that.."
Twin Cities, MN
Joined Feb 2010
1,063 Posts
Wow right through the cornstalks! You've got incredible flying skill Wart! I wonder how you'd do with a Trex 600... what a sight that'd be to see one of those plow through a stalk lol

Quote:
 Originally Posted by warthox push it to the limit and through corn
Sep 01, 2010, 11:42 AM
That tree again!!!!
Germantown, MD, US
Joined Sep 2004
6,645 Posts
Quote:
 Originally Posted by SSM ... that for each one (1) turn of your rotating disc, the nail in the center makes one (1) turn. And the nail that's away from the center makes .... well, it also makes one (1) turn. ...
You're right. They rotate with the same speed. So the effect of the gyro should be the same.

Quote:
 Originally Posted by Mike Barton ... So I'm tempted to say it probably doesn't matter, but this is just my opinion.
I'm wondering what kind of effect (if any) would the higher displacement speed cause to the gyro?
If i put my heli tail gyro at the end of the tail boom of the heli (almost 1m long, yes too extreme) would that work as well as when i put it in the heli itself?

Ah, I think it doesnt matter as heli or any other high speed plane also moves the gyro quickly and the gyro still works fine

Thanks

thanh
Last edited by thanhTran; Sep 01, 2010 at 12:00 PM.
Sep 01, 2010, 11:53 AM
Registered User
Girona, Spain
Joined Dec 2007
49 Posts
Yesterday I could do a quick test of my tricopter.
The day was very windy and only raised it a few seconds to see if everything worked correctly.
The board works great, now wait for the weather to improve to make adjustments to the gains of the gyros and trim settings.

Thank you very much to Niall, fulg, corbystarlet, spagoziak for helping me put my tricopter in flight.

Here is the video of the short flight; back in the trees can feel the wind.

 1º test tricopter KK controller (1 min 11 sec)