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Old Aug 06, 2011, 03:03 AM
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Originally Posted by Melnic View Post
remko, I did that back in June
In the case of the doghouse, it was not to deal so much with the wind but the bad tendancies of well, a flying doghouse. It was MUCH better with the gyros.
I also dissagree with his formula. I mounted mine angled at more of an angle since the pitch is less sensitive than roll
http://www.rcgroups.com/forums/showp...postcount=1107
Hi Melnic,

I really like the "doghouse", looks pretty fun in the sky..

But i dont think that his formula was based on a flying doghouse at that moment.
pursenally i'l would try to go around 110/120 deg angle with Snoopy's house.

(In your video you say that the angle of the gyro's is set to "60 deg", that looks to me like it's set for more pitch control then roll controll.)
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Old Aug 06, 2011, 08:08 PM
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Scott, that was a superb report on the GA-250. Thank you for all your testing and analysis.

Assan should be sending you free gyros and servos just for your real-world feedback. As a matter of fact, I think they should be PAYING you for what you are doing. And in the end, perhaps you could write a user manual for the 250 and they could buy it from you. But knowing the Chinese penchant for using intellectual property, it probably won't happen.

Dick
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Old Aug 06, 2011, 09:43 PM
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yes, it was angled more towards elevator. Pitch axis typically can withstand a higher gain than roll. Hence I put it at about 60. 45degrees from front would be half way. 0 is all aileron and 90 is all elevator. That's how I'm describing it.

Since every plane I've flown so far can have a higher roll rate than loop rate, that's what i'm going by
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Old Aug 07, 2011, 03:33 AM
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United States, WA, Richland
Joined May 2009
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GA-250 .. mixed results

As it turns out I only had opportunity for one flight with the gyros today. We have several new members and there were only two of us to buddy box them today ==

So for this one flight I had mixed results. Unfortunately there was very little wind. (never thought I'd say that about flying). There were no negative issues on rate mode. In fact the rate mode flying seemed incredibly crisp and precise -- but -- it's hard to tell without adverse conditions. I cranked the gain way up on rate -- but this is a slowish foamy powered glider. I'm not ready to put them on a faster powered ship yet.

Something went amiss on AVCS (HH) mode. I've not had time to check into this yet, but twice when flying level I turned the knob to AVCS and the flipping plane took a detour to the earth. Straight down. The second time I tried to turn the knob back so quickly I pulled the knob off of the TX. and then nearly wet myself. Similar phenomena with the roll gyro. At that point I didn't know what to do with the knob in my hand and couldnt' easily get it in a pocket (because I fly sitting due to recent foot surgery) -- so I put the knob in my mouth and landed.

The good was the rate mode. Really really sweet --- but not an adequate test -- only about 10 minutes of flight time on rate. I'm not giving these gyros a break either. I hot melt glued them into place. (I'm waiting for Melnic to say "you mounted them with WHAT!!) I really really doubt that the mounting is related to the crazy behavior in AVCS mode -- but .. .maybe tomorrow I'll get lucky and we'll have a 20mph wind. I'd like to sort out if I did something wrong or what. I've always avoided AVCS in the past -- and maybe now I know why

If Assan paid me I couldn't be honest ... I have however reported a problem to them before anybody else so they had time to fix it before people went nuts.. I'm really only interested in their product because the mems technology intrigues me and mems at this price is in the "too good to be true" category. O ya, also because gyros this small could have interesting applications for winter indoor flying. I'm interested in the GA-410 too for the same reason (mems), but I've got more than enough on my plate to keep me busy now, and the tracking on the GA-250 I ordered from HK shows they will be here on Monday ..so more playing to do. The 410 and 510 appear to be easier to set up -- but if I try them it will be only one.
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Old Aug 07, 2011, 09:24 AM
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you have the gyro gain on a knob?
Which axis?
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Old Aug 07, 2011, 10:43 AM
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Quote:
Originally Posted by scott page View Post
Something went amiss on AVCS (HH) mode. I've not had time to check into this yet, but twice when flying level I turned the knob to AVCS and the flipping plane took a detour to the earth. Straight down. The second time I tried to turn the knob back so quickly I pulled the knob off of the TX. and then nearly wet myself. Similar phenomena with the roll gyro. At that point I didn't know what to do with the knob in my hand and couldnt' easily get it in a pocket (because I fly sitting due to recent foot surgery) -- so I put the knob in my mouth and landed.
You're lucky that's all that went wrong. One more thrill during your flight and you might have swallowed the knob.

Sounds like good news as far as Rate goes. Rate is all I ever use, so my only other concerns would be ease of setup, whether you must initialize in AVCS (prefer not to), and what settings are required to stay out of AVCS while flying.

In a prior life I worked as a research flight test engineer. I've worked around and flown a goodly number of control schemes in full scale airplanes, including Rate Command (not the same as rate damping), Attitude Command, Heading Hold, etc. From what I've seen, each of the more advanced control schemes has it's advantages, but also come with big disadvantages. For overall simplicity and ease of flying, it's hard to beat direct surface control (what R/C'ers do now) with a bit of rate damping.

One idea that hasn't been explored much yet is tailoring the Rate gain to the flight condition. Right now it's common to have a switch to raise or lower gains in flight, but what I'm suggesting is that the gain be mixed with some other command. For instance, on a jet it might be good to have higher gains with the landing gear down and then reduced gains with gear up.

Dick
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Old Aug 07, 2011, 12:32 PM
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Originally Posted by otrcman View Post
One idea that hasn't been explored much yet is tailoring the Rate gain to the flight condition. Right now it's common to have a switch to raise or lower gains in flight, but what I'm suggesting is that the gain be mixed with some other command. For instance, on a jet it might be good to have higher gains with the landing gear down and then reduced gains with gear up.
This is easy to mix.

I have 3 gain settings on my gyro's, 25% for fast flight, 45% for slow flight (high alpha) and 0% to turn the gyro's off.
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Old Aug 07, 2011, 01:44 PM
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This fellow seems to have found an even better way, but Ill tell you his customer service sucks as I can't get a hold of him.
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Old Aug 07, 2011, 02:38 PM
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Originally Posted by TheNiceGuy View Post
Good to know, thanks.
I posted this elsewhere, and realized this thread may be more appropriate. I have kind of a weird application for gyros. I'm looking to make a replica of this ball VTOL:
http://www.rcgroups.com/forums/showthread.php?t=1454102
If I have it figured correctly, I'll use 8 servos: 2 elevator; 2 rudder; 4 elevons. These will feed into 4 seperate RX channels. So I will need 4 gyros to stabilize the aircraft: 1 rudder; 1 elevator; 2 elevons. Correct?
Will there be any conflict running 2 gyros on the same axis?
I'm thinking these GA-250s because they are light and cheap.
What do you think?
Thanks for any help.
kk flight controller is the next step forward for you bruv just incase it hasnt been mentioned
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Old Aug 07, 2011, 07:46 PM
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Originally Posted by TheNiceGuy View Post
This fellow seems to have found an even better way, but Ill tell you his customer service sucks as I can't get a hold of him.
That is pretty intriguing! Mixing with the gyro is something I'm planning to play with .... About 3rd on my list. I suppose I could use eepe to simulate this now and get to trying it out in the future.
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Old Aug 08, 2011, 11:07 PM
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Can someone help me in setting these GY48V up?
I plugged them into teh aileron channel, and the adjustment wire into channel 7. Channel 7 is adjusted by a knob on the face of my TX. If I crank the knob left, it turns into HH mode (LED on). If I crank right, its RATE mode. There seems to be sensitivity in each by how far I move from "0" on the knob. However, it doesn't really matter how I set them, as they are constantlyt chattering and freeking out - non-stop. They just do more so the farther I move from "0". It doesn't matter where I dial in delay or limit on the physical gyro. HH or RATE. Or gyro position or non-movement. All don't matter, they are freeking out all the time.
I have them set to DS - OFF, and have tried normal/reverse.
Used 2 differnt analog servos. Am using a PCM 1024 Futaba FF8 radio and PCM 1024 RX.
Any ideas?

I'm starting to get fed up with this fiddling and getting a stiff neck. I have enough irritation in my real life. Bah!
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Old Aug 09, 2011, 07:24 AM
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Have you tried Googling GY48V? This gyro has been out since 2009, and there seems to be a lot of info on it out there, but most will pertain to setting it up as a heli tail gyro. Nevertheless, you'll find real good solutions that will pertain to what your experiencing.

Anyhow, check the ball link distances with respect to their axis of rotations. There are minimum distances needed for these things to work properly. For example, you may have the ball link too far out on the servo arm....this will cause too high a mechanical gain which may result in what your experiencing....twitchy servos. Or...you could have a bum gyro.
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Old Aug 09, 2011, 08:37 AM
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Assuming you're talking about chatter while not flying, I disagree that it's anything to do with the ball links.

Have you mounted the gyro yet? If the gyro is being held in the hand or not properly stuck to the airframe, the tiny vibrations that the gyro will pick up cause constant chattering to correspond with the constant motion. It's actually performing as intended.

If the gyro is placed on a solid surface (or mounted in the plane), in such a way that it can't be moved by vibrations in the wires from fingers etc, do the servos settle down?
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Old Aug 09, 2011, 08:41 AM
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Also, depending on the servos, some digital servos have very little deadband and you will get the chatter. My EXI D227F servos may chatter while some of my other cheaper analog ones do not. For rudder, I typically use an analog servo with the gyro. For ailerons, I often use a digital if I want more precise control.
As Davee1 points out, it will chatter even more if not mounted. Hence I stick the gyro to a hockey puck in my videos for demonstration.
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Old Aug 09, 2011, 09:59 AM
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I am testing with a couple of new servos not mounted in the plane, to make sure it works and save a lot of grief if something frys as my aileron servos are hard to replace. I have tried several startups, including not touching a thing and connecting battery. Gyro is on the table untouched and servo it constantly moveing.
Is there some setting in the radio I need to change? I just left it as it was and adjusted using the face knob.
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