Picked up a used Gaui 200

[9sec240]

Full left piro (rudder left) would be rotating opposite main rotor which means the tail blades do not have to work hard (or at all for that matter). Full right piro (right rudder) would put the biggest load on the tail blades as they have to work against the torque of the body created by spinning the main blades. To me this would indicate the tail is not working well. What happens when you hold the tail rotor still and try to spin the main blades? Is anything slipping? Belt jumping teeth?

[Jerrymac]

Scott, the tail don't hold in rate mode or HH mode. There is as much pitch in the blades as possible with the tail design. Can't get any more pitch.

Ivan, the belt is a little loose right now. I can hold the tail and if I turn the main shaft hard enough it will jump a tooth. I tried to tighten it up a little and the belt broke on spool up. I replaced the belt and made it tight enough so it would not jump a tooth, but then it broke again on the first spool up. The belts are not very strong at all. The only way I can keep from breaking them is to leave them a little loose.

The last time I had tail troubles like this was on my cheapo King2's, but I put the 43 tooth tail drive upgrade gear on them and it helped. Not sure what to do with the Gaui 200 to get more tail authority.

[dunkonu23]

I should have been more clear... I meant tail moving to the right... like if you have correction direction wrong on the gyro, it will spin nose left, tail right.

Scott

[9sec240]

I actually have been slowing down the tail on my 200s because they are too sensitive. I have the 17 and 18T tail shafts for that.

The belt tension is pretty tough to get right. Most people set it up loose enough where it will just barely skip teeth of you use medium pressure on the head / tail. Too tight and you can stretch the belt. I had a couple belts that got stretched in one spot and then they would get "curly" in that spot. This allowed the belt to flip over tooth side out and slip a bit. The tail would not hold well at all then.

If you feel that mechanically the tail is correct, maybe it is time to change out the gyro / tail servo. There is the possibility that the gyro is not working correctly or the tail servo just does not have the torque to make the pitch changes during flight.

[Jerrymac]

As far as I can tell, I am pretty sure that everything is set up right mechanically, but, I must be missing something here. Ivan has to slow his tail down with a larger tail gear, and I can't seem to get mine fast enough to hold.

I think I will take some more time and go back through the whole tail and see if I got something wrong. I am certainly no heli expert, but I have put together several others before this and never had this much tail trouble before. Could just be something simple that I missed, like the tail bounce on my 425 when I first built it. I fooled with it for quite a while before realizing that I had the servo setting on the gyro wrong.

Also, since I bought this heli used, I am not sure if there were problems with it that might have been caused by it's previous owner, and he sold it out of frustration, lol.

[Jerrymac]

Hmmm, what a difference 1.5mm makes. Saturday night I tinkered with the 200 a little more. I removed the 'jam' nut from the tail output shaft, then unscrewed the tail hub about 1.5m. Put some 'wicking type' loctite on it, then put the jam nut back on with a drop of loctite. Re-adjusted the servo travel limits and tightened the tail belt just a little. This gives the tail blades a lot more pitch, even though it is not assembled "by the book".

Took it out to the field Sunday evening and it flew great. The tail would swing out about 10 degrees on a full collective punch-out, but came right back again. Slow servo is my guess. Just need to set the rudder travel limits now to get even piro rates for both left and right. A faster tail servo should stop the minor turning during a hard punch-out, but, for now I am pretty happy with the way it flys.

[dunkonu23]

Sounds good, Jerry! Modding like that shouldn't really be necessary, but it sounds like you pulled it off!

Scott

[9sec240]

Interesting Jerry. Really glad it is flying OK for you now. I just ignore the small tail issues. If you could see how bad the tail moves around on my Trex 250 when I bang it around you would probably laugh. Overall it stays in about the correct spot so I just ignore it.

[Jerrymac]

Scott, if you saw the tail design, you would see that the blades just didn't seem to get enough pitch when giving right rudder. Wasn't really much of a mod, it just moved the blade hub closer to the end of the tail shaft so the pitch slider has a little more travel.

Ivan, I didn't really expect the tail to hold as well as it does on my bigger birds, but it was real bad so I needed to try something. I am not that good of a pilot yet, so a poor tail makes it much harder for me to fly this tiny heli. It is not perfect, but holds well enough for me to feel more comfortable flying it around more.

BTW, I like those Hyperion 900mah 45c batteries. I had my timer set on 4:00 while breaking them in and trying to get the heli sorted. After 5 flights on them @ 4 minutes I am only putting back 350mah. I could probably easily get 6 minutes flights with them.

[9sec240]

They are 2S right? I really need to get my Gaui 200 flying again. I have a second one too that is brand new and not even built yet. Batteries are part of the issue for me. I have 6 or 8 Turnigy 800mAh 2S but the Gaui just eats them up. 4 min flights just suck.

[Jerrymac]

Yeah Ivan, they are the Hyperion G3 EX 900mah 2s 7.4v 45c/90c . They are $17.95 at AlleRC.

www.allerc.com/product_info.php?cPath=3_4_93_157&products_id=5443

[9sec240]

It is coming up on "dome season" and I have to get my ducks (helicopters) in a row for it. As much as I enjoy flying outside, I am really itching to get cracking on inverted orientation training.

[Jerrymac]

Yeah, I remember seeing some of your 'dome' vids over on RCU last winter. Wish I had someplace like that to fly in during the winter. I just go outside and freeze if I want to fly in the winter.

[Jerrymac]

Well, I seem to still be having a small problem with the 200. I took it out today and it flew great for about 2 min then the tail started acting up. I landed and looked it over and found that the belt flipped over on the drive gear.

I took it apart at the field and re-aligned the belt, then tightened it up pretty tight. On the second flight, the same thing happened. Not sure why the belt keeps flipping over as I had it pretty tight, and it is a fairly new belt with less than a dozen flights on it.

[dunkonu23]

That is odd. I've heard of it before on the Black Hawk helicopters, though. I don't remember what the fix was, though. Seems to me that it's a torque issue. That the belt doesn't have enough bite on the drive and output gears so it just eventually gives way to the 90 degree twist.

Scott

[9sec240]

Jerry, on mine, this would happen if I tried to tighten the belt too tight. What was happening was one small section of the belt would stretch and then get a funky twist to it. This small section would cause it to flip. Pulling the belt off made it easy to see the twist. No matter how I tensioned the belt after that, it would not stop flipping. The only fix I found was belt replacement.

Be super careful when installing a belt. There is a "just right" tension. It should just skip teeth with medium pressure on the head and tail.

[Jerrymac]

Hmmm, I never had that problem with my Blackhawk Scott. The only problem I had was the belt wanting to ride off of the tail pulley. Removing the guide wheel solved that problem.
I will have to order a couple spare belts for the 200 since I don't have any more. Getting the tension right must be pretty critical on this bird, huh Ivan? When I had it a little too loose the tail would not hold at all. When I tightened it up, the tail held pretty good for a couple of flights, then the belt starting flipping over. Grrrrr

[Jerrymac]

Well, I ordered 3 tail belts tonight so I have some spares. So far I am really having a lot of fun flying this lil heli, except for the tail issues. Hopefully I can get the belt issue resolved as it seems the belt is kinda finicky when it comes to proper tension.

[dunkonu23]

Cool. I hope the belt sorts out the problem, Jerry!

Scott

[9sec240]

Just slowly work tension up till the tail holds correctly. It is a PITA but once they fly well, it is worth it.