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Old Aug 14, 2011, 03:57 PM
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United States, NY, Wolcott
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Originally Posted by Silverexpress View Post
I saw a couple in heli-for sale forums - averaging $55.
Found some on EBay for the same price with free shipping. The way I read it they won't work with JR digital servos? Bummer as that's what I have. Well, Spektrum actually.
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Old Aug 14, 2011, 08:31 PM
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scott page's Avatar
United States, WA, Richland
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Ga-250 question

If you have returned GA-250 to Assan for a firmware update ease PM me. I have a question.
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Old Aug 14, 2011, 08:46 PM
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Originally Posted by jrjr View Post
Found some on EBay for the same price with free shipping. The way I read it they won't work with JR digital servos? Bummer as that's what I have. Well, Spektrum actually.
I think it was only certain ones. But you should be able to run it in analog mode. For an airplane, digital mode is not as important as a heli tail. It does help for ailerons though a bit. But not so critical.[
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Old Aug 15, 2011, 07:35 PM
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Warning for ga-250

I don't want to be melodramatic but this could be a huge issue if you have GA-250s.

First before I say any more you need to know that Meng at Assan has be completely upfront and honest and had done everything in his power to set things right for me -- and others...and if necessary I'm sure he will for you as well.

First Issue I detailed here last month. I can't say which color label this will effect -- and it may affect ALL of the GA-250's purchased to this time.
The effect is that while in operation, the servo will become locked out and you have no control over the servo until power cycling (unplugging and plugging back in). The cause: The signal wire operates in a range from -100 to 100. The highest rate mode is -100, and the highest AVCS is 100 with 0 being essentially no motion and it is at about 0 the gyro switches from rate to heading hold. IF the signal wire -- say channel 5 is right on the cusp of the two rates...say sometime between -10 and 10 then the gyro can switch to servo select mode. The effect of this is the gyro locks out signal to the servo until the power cycle. Where this would bite an airplane guy would be if they set a switch to kill the gyro effect -- and this would essentially be delivering a signal of about 0. If you hook the gyro to a pot you can cause this to happen very reliably. simply start with rate mode and slowly rotate the pot. When the blue light comes on, stop, back up a bit, and find the point where the blue light flickers...then suddenly a red LED starts to flash with a code of between one and five red flashes -- corresponding to the servo that is currently programmed. Here is the second place this bug and strike. You may not know you entered servo select mode and change the servo type you've selected. This will not take effect until the next time the gyro powers up...and if you've got an analog servo you might need a fan to blow the smoke from the room. I know!! Ok, basically you can assume that all of the GA-250's purchase to this point have this problem. There are probably still about 1000 or more in the supply line that have this problem. Until HK sells out and restocks all they have will have this problem.
IF you have a gyro that has this problem, contact Meng at Assan and he will invite you to ship the gyro to him and they will flash new program onto it. I sent 4 back and it was about $4.

This second problem will probably not affect anybody because I think they got a handle on this.
Apparently I received the first gyros with fixed software. -- that is the problem of switching to the servo select mode. Unfortunately the software engineers at Assan did not engage the time tested practice of retrograde testing (checking to see if a patch of fix causes other problems) and these gyros arrived with a devastating flaw.

You may remember about a week or so ago I reported that my tests of the rate move were stellar. They were incredibly awesome. They beat the H out of any piezoelectric gyro available at any price. I ALSO said I had not completed testing AVCS/HH functions. This was because early on something felt wrong and I did not have the time to run it down..so I set the limits on my TX for the signal channels from -100 - 0. This effectively kept me in rate mode and I had alot of fun. Then it came time to try AVCS....Saturday. It was windy as heck and when I launched my sky surfer (test plane) I had about 30% rate mode in the roll axis.... I had just come up to speed...about 30 feet high and thought I'd shut off the gyro until I was ready for the test. Rather than use the switch to flip it to zero I used the pot and entered AVCS... but just barely. Just barely didn't matter however -- the new fly in the ointment was that the gyro REVERSED the throw of the servo once it entered AVCS, I did not have enough time to process the situation and save the plane, although a stick of hot melt glue and it's ready for more testing. AT THAT TIME I DID NOT KNOW FOR SURE WHAT THE PROBLEM WAS. I'm using new Turnigy 9x radios with er9x software. I'm very enthused about these radios because they have been stellar so far. Of course that was my first suspect. The other pilots attributed the crash to the wind. I hit instant replay in my head over and over and realized it was not the radio because the problem was only roll and it seemed to me the left roll was worst as I added right aileron. Yesterday I mocked up the situation on my work bench. It didn't take long before I realized that I had probably been in AVCS inadvertently -- and only a few minutes after that that I understood that the gyro was reversing the servo output when it was in AVCS. The radios were still not off the hook. Out came my Futaba receiver and TX ... same result. Another hour of so of testing and I contacted Meng.

Here is some good stuff. Meng tested the situation and with a couple hours had contacted me twice - first to let me know they were testing my findings -- and secondly to let me know they had confirmed my findings. We exchanged several more notes, and ultimately Assan has notified all users that received this bug when sending gyros back for upgrading. Also they recalled all gyros with this bug that were still in China postal system. So the end result is nobody should see this happen in their GA-250. Just the same I think it's is prudent to be aware of it and test GA-250 for either of these bugs.

Actually if a person only wanted Rate mode or only wanted AVCS it's easy to work around both bugs. Simply use only that feature and set limits so you don't even get too close to the center point.

My final comments. I've never seen a company acknowledge a mistake as readily as Assan did. While somebody dropped a big serious ball in their engineering department -- I'm fairly confident that will be taken care of in house. I'm astounded that they have been so good about offering to flash new software to any gyros returned to them. I won't have the next version of the software until probably early Sept. You can bet I'll give them a thorough testing again and let you know.

When the bugs are stomped on these gyros they are going to rock the gyro world. Like I said earlier -- I've never seen such incredible performance -- but I've also never seen such nasty bugs either -- at least they are easy to recreate and remedy.

My apologies to Meng and Assan if my post causes them any damage. This is not intended in any way. In fact, it should do the opposite -- it should demonstrate that they are an upright company that stands behind their products.
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Old Aug 16, 2011, 03:42 AM
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Japan
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I got the gyros working on a testflight on my elevon firefly.
Need to clarify before flying on my photo plane -
plane can be in any position (upsidedown)during initialization as long as not moved?
on the gyro- delay set to 0, limit at 100?

Regarding photo plane, I have ATV on my ailerons (60%) and elevator (70%). Gyro limit screw at about 100. Ailerons seem to be over extending and binding at full stick. IIUC, I need to set ailerons to 100% ATV in transmitter, and adjust horns, etc. to accommodate?

Also, I have both gyros' gain wires on knob controlled channels (ch6/ch8). They work well, but require dialing near 0 on the 2 knobs to approximate a turn off. I have looked through the TX options and can't find a way to bind these knobs to switches or better yet a single switch that can be hit in flight. I can do that to teh AIL and ELE channel themselves, but not just the gyros.
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Old Aug 16, 2011, 10:51 AM
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Scott,

From you experience so far, can the GA-250 be powered up in either Rate or HH ? Or does it have to be powered up in HH like a Futaba 401 ?

Also, what is it about the 250 that impresses you so favorably ?

Thanks,

Dick
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Old Aug 17, 2011, 01:20 AM
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United States, WA, Richland
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Originally Posted by otrcman View Post
Scott,

From you experience so far, can the GA-250 be powered up in either Rate or HH ? Or does it have to be powered up in HH like a Futaba 401 ?

Also, what is it about the 250 that impresses you so favorably ?

Thanks,

Dick
I power them up in rate when flying planks. I'm impressed with how crisply and precisely they operate and how resistant to vibration artifacts -- (the bugs aside). O -- ya -- and how cheap and small they are. I'm going to put three on a tiny indoor foamy just for fun -- and I'm not (too) worried about the weight. Once the bugs are squashed ..... I can't tell you how much I hope they get it right this time.
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Old Aug 17, 2011, 06:22 AM
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Originally Posted by scott page View Post
I power them up in rate when flying planks. I'm impressed with how crisply and precisely they operate and how resistant to vibration artifacts -- (the bugs aside). O -- ya -- and how cheap and small they are. I'm going to put three on a tiny indoor foamy just for fun -- and I'm not (too) worried about the weight. Once the bugs are squashed ..... I can't tell you how much I hope they get it right this time.
How tiny? I was thinking of putting one in a Parkzone UM P51 or Trojan. I would connect it to the aileron servo without its case.
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Old Aug 17, 2011, 11:27 AM
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scott page's Avatar
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Originally Posted by Silverexpress View Post
How tiny? I was thinking of putting one in a Parkzone UM P51 or Trojan. I would connect it to the aileron servo without its case.
Mount it @ the CG and cut out the extra wire length.

Its <1" x <1" x <.5" or 21mm x 21mm x 10mm and 8 grams including wire loom. You could probably cut the mass to nearly half by case and superfluous wire reduction.

I wonder if my PIA UM Sukhoi would be controllable .... Hmmm.
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Old Aug 17, 2011, 12:25 PM
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I have beenusing gyros on my airlerons on my planes fore ~ 2 years now and love them for flying in high winds. Unfortunately I have lost several planes to sudden and unanticipated wing tip stalls due to the fact that the gyros disguise the approaching stall. Any thoughts on how to avoid this down side to using gyros?
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Old Aug 17, 2011, 02:58 PM
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Old Aug 18, 2011, 02:20 AM
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Originally Posted by swordds View Post
I have beenusing gyros on my airlerons on my planes fore ~ 2 years now and love them for flying in high winds. Unfortunately I have lost several planes to sudden and unanticipated wing tip stalls due to the fact that the gyros disguise the approaching stall. Any thoughts on how to avoid this down side to using gyros?
Not sure how much they really disguise approaching tip stall - the plane that I have that is prone to them does it with no warning without a gyro! What a gyro will do is lock the plane into the spin by applying full aileron, so I'd suggest having a gyro kill switch that you use during spin recovery (if your tip stall doesn't occur at low altitude! )

One way to help avoid tip stalls would be to avoid using outboard flaperons (guess you aren't unless mixing on plane) but to use separate inboard flaps. They will reduce the angle of attack of the wing tip for a given speed.

Also, gyro on rudder could perhaps induce tip stall if a gust over one wing caused yaw, as strong rudder input near stall can cause a spin.

Other possibilities include reducing wing loading, adding wash-out and flying faster and giving less elevator and rudder in slow turns.
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Old Aug 18, 2011, 11:31 PM
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Hello, I'm thinking about installing a gyro on my foamie, but I was hoping to get a recommendation. I know next to nothing about these, so after looking here I started looking at the Detrum GY48V (http://www.xheli.com/60p-dy-1017.html) - do I need two of these? (I assume it connects between the servo and the receiver, but I only see one female connector). I'd rather get just one gyro that will work with both of the servos that control the ailerons (is that possible?). Can someone recommend one that is easy to install/setup (not looking for anything too fancy or expensive just yet)

Thanks!
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Old Aug 18, 2011, 11:38 PM
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United States, WA, Richland
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Originally Posted by vinsonj View Post
Hello, I'm thinking about installing a gyro on my foamie, but I was hoping to get a recommendation. I know next to nothing about these, so after looking here I started looking at the Detrum GY48V (http://www.xheli.com/60p-dy-1017.html) - do I need two of these? (I assume it connects between the servo and the receiver, but I only see one female connector). I'd rather get just one gyro that will work with both of the servos that control the ailerons (is that possible?). Can someone recommend one that is easy to install/setup (not looking for anything too fancy or expensive just yet)

Thanks!
Whatever Melnic says is GOSPEL in my opinion. I believe the GY48V is his weapon of choice. I will recommend you do not use the GA-250 at this time. It's still not gotten a clean bill of health. (new product, still some bugs)
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Old Aug 19, 2011, 09:11 AM
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Originally Posted by scott page View Post
Whatever Melnic says is GOSPEL in my opinion. I believe the GY48V is his weapon of choice. I will recommend you do not use the GA-250 at this time. It's still not gotten a clean bill of health. (new product, still some bugs)
Well, that's good enough for me....just need to figure out how many I need....
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