biggerswede

Hi!
I just got my hands on a GWS Dragonfly. The mysterious thing is what seems like temperature drift in the tail control. At initial turn-on it acts normal for a minute or two then the tail rotor starts spinning at gradually increasing rpm, still with no throttle and no head rotation. The heli will stand parked on the floor rotating slowly to the right with the rotor standing still. Giving left rudder doesn´t stop it. Rotating the whole heli right stops it. The strangest thing is that in flight it still behaves OK. I know that piezo gyros are temperature dependent but wouldn´t that also affect the rudder trim in flight?
What worries me except for the battery drain is the risk that that with the tail rotor blocked after a crash (about every third of my landings) the tail motor might fry.
To isolate the problem to the heli or the xmitter I just gave the xmitter a warm-up time before I connected the heli battery. Same thing happened. Seems to be in the heli...
Any ideas anyone?

harty

i have just purchased the same item and i am getting the same problem what mixer gyro are you using
mine is this one GWS PHA-01 3 in 1 Gyro, Mixer and Electronic Speed Controller. As found in the 2004 GWS Dragonfly.
i find if i reset the power to the unit it will fix it

regards
peter

justin_92_92

My Feedback: (2)

your gyro is on rite? Thats my guess so far. I will think about it more.

biggerswede

Sure my gyro is on. I turn on the xmtr with rudder trim approx centered throtthle down, then I plug in the heli flight battery. Waiting while not moving the heli until I get a green light on the mixer board. Then In just need to wait one or two minutes for Hell to break loose. Resetting, i e unplugging and replugging battery helps.
This is a gyro drift problem. Is it a general Dragonfly problem?

drgoran

I've the exact same problem. After a while i get the same behaviour as my fellow swede. I'm gonna call my model shop tomorow and ask them for advice. Will post their answer here!

waimate

I get this exact same thing as well. From doing some research on the net, I found GWS recommending a bit of a hack job, which I tried. I relocated the PHA-01 gryo from inside the casing to outside, where the receiver used to be ( I relocated the receiver aft). I also removed the PHA-01 casing to try to increase airflow to the MOS-FET. This helped "a bit", but did not fix the problem completely.

My impression is that it's a design flaw in the PHA-01. It simply cannot handle any sort of heat build-up, and takes quite some time to settle down afterwards. It's winter here in the southern hemisphere (18 degrees C daytime in Sydney), and I wonder if the problem will be even worse in summer.

biggerswede

Drgoran, probably no point in asking Wentzels or any of the Stockholm shops. I tried and no one had anything else to say than "call Minicars in Uppsala, they should know"
The "expert" at Minicars denied that he had ever heard of that problem before but offered me a new circuit board for something like SEK 690 (about $90)
Also noticed that outdoors in the evening (at best no wind and temp maybe 10 C) It doesn´t drift the way it does indoors at maybe 22C. Definitely a temp problem.

drgoran

I was at Wentzels yesterday and asked them about the gyro problem and the guy I talked to had heard of a couple of others with the same problem. He promised to contact minicars himself. We'll just have to wait and see what it leads to...

harty

there is a problem with the gyros they suffer from thermal drift as they heatup if you monut them outside the case it helps a bit

drgoran

I actually tried to mount it on the outside last night. It got better, but it's not good yet. Extra fan? Heatsink?

No "official" reply from Wentzels either...

tartao

Hallo all,

I can confirm the same problem but I maybe have another one with the tail:

giving more throttle than needed for hovering I can't keep the tail straight
even with full rudder right...

It climb but turning on the rotor axe till I give less throttle.

It seem that the gyro dosn't provide enough power to the tail motor...

Someone has the same problem? Is it maybe needed to trim the gyro itself?... How??

Best regards, Andrea

kagreen2k

I had the exact same problem with my Hummingbird. I ended up sending the board back and getting a replacement.

kagreen2k

I forgot to ask if you tried adjusting the mix. In my case, I had the same behavior that you described with the mix turned all the way up.

flacken

I know nothing about this but remember i read something about a tail problem on this page, hope it helps

http://www.gws.com.tw/english/produc...ly/026-300.htm

tartao

No, I didn't... after playing with it things went better but now... I ran out of tail rotor blades!

I'll have to wait for the replacement to arrive...

I'll keep you informed!

Ciao, Andrea