RunRyder - Gasser waggin' like a dog.

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Gasser Model RC Helicopters > Gasser waggin' like a dog.

daggit
Elite Veteran
Location: Waseca MN

I was out today with my newly installed GY401/ digital servo combo. I still have a wag.

At first I thought it was a tuning issue, but I tried every needle position and gyro gain setting under the sun with the same wag. I finally just put it to where it seemed to be running the best. On spool-up just before lift off the motor doesn't stay at a constant speed (at any needle setting) Once airborne I don't notice any engine speed change but the wag is bad with a little drift too boot except for when descending then it's sweet!! .

I have a couple theories... hopefully someone can steer me right...

Could my headspeed be too high and causing this?

Could a bad coil cause inconsistent engine speed (starts great)?

I don't run a governor and I don't have anything to check headspeed, but it seems pretty fast. Next time out I figured I'd mess with the throttle/pitch curve to get my headspeed down.
buy the way... I'm running an Xcell graphite gasser with g23 PUH motor, 710 symetrical blades, 8103 radio, Gy401/9253 digital servo, 603t carb

04-03-2003 Over year old.

HOMEPAGE

Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Dag, you're gonna need to get that motor running first, or nothing you do will work. The wt603 appreciates less oil. What did you settle on for a mix?

04-03-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

64:1

04-03-2003 Over year old.

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bmfrd
Heliman
Location: Maryland

Tail Wag

In my experience, with both Vario and Min Air, an appreciable tail wag is related to the head speed. My Vario Benzine(720 main blades) likes a head speed about 13-1400. Much above 1500 the tail wags significantly. The Min Air(700 main blades) will run heads speeds in the 1500 w/out wag but it becomes noticeable above that. I'd check the head speed first and slow it down.
The g23 runs better at slower speeds as well. What grade gas are you running? I've had less trouble tuning the motor running regular(87 octane) and 100:1 AMS oil. Both the Vario and the Min Air seem to run well with this.

04-04-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

thanks for reply...

yes 87 octane Amaco gas w/Amsoil 100:1 mixed at 64:1.

What's confusing to me is I was running it 3 weeks ago and everything was fine. Same can of gas, same everything. I think it's just gonna take some fiddling.

how does one determine if a coil is bad. I don't think mine is y et, but I was wondering what the signs are.

.

04-04-2003 Over year old.

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Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Dag, when a coil is bad, it won't start. Coils are usually open (not good) or not (good). A gasser needs a strong gyro. The GY401/9253 is on the minimum side of acceptable. If your tuning is off, it will drive the gyro nuts. We run head speeds much higher than 13-1500 for sporty type flying.

04-04-2003 Over year old.

Malorie
Elite Veteran
Location: Paw squared, MI

I agree with rchelial, look at things like gyro mounting, motor tuning, etc. I rgularly run 1750-1800 on my gasser with no tail wagging.

Life's a journey, NOT a destination.

04-04-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

thanks for input...

it's cold, windy, and snowing right now. I have ants in my pants to get out and work on that heli!!

04-04-2003 Over year old.

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daggit
Elite Veteran
Location: Waseca MN

by the way, what do you mean by " strong gyro"?

I had some tail drift (minor)I couldn't get rid of with my JR 550, that's why I switched to the GY401. I have used this on other helis with excellent results (so have others I know). Thought it would work better.

04-04-2003 Over year old.

HOMEPAGE

Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Well, you need a gyro that is mounted well first off. I use only the CSM mounting foam tape. I don't care for the Futaba stuff supplied with the gyros. If you are not into the crazy backwards stuff, use a servo arm dimension of 16-17mm. What tailblades are you using? Next, get that motor to behave. The spot ,you speak of, just before it lifts off is where the carb hovers. You are not changing the carb opening much from just before liftoff to hover, so if it is unhappy there, it's unhappy hovering. You say that it is decent coming down. This is an unloaded state basically, so I would guess your midrange is lean, once loaded back up with pitch. I would have to see it fly to be sure, but i would work on the needles more. Gassers like to grunt, not freewheel, so the right fuel curve is important.

04-04-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

Thanks, I have lots of options to improve my situation. Gyro mounting is one thing I hadn't considered yet.

This issue WILL be resolved when the weather clears

04-04-2003 Over year old.

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Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Your taking some nice pics there, by the way!

04-04-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

In regards to gyro mounting...

I had to relocate it from the manufacturers recomended location which is on the back of the frame behind the motor because of the muffler upgrade. I used the Futaba supplied sticky tape. The picture is rather large so you can see it up close. What you can't see is that under the gyro the metal parts it is attached to are NOT connected, They are 2 separate pieces mounted in apposing level positions very securely. Maybe I should rethink this? I didn't expect any problems from this setup but now I'm re-thinking

04-05-2003 Over year old.

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Cassini
Senior Heliman
Location: Enterprise, AL

I have a X-Cell Gasser and I upgradded to the rear muffler many years ago. I moved my gyro to the forward radio tray area using the same clips you used which were from the rear.

My brackets are mounted right above the two screws that bolt the metal dogleg support arms to the plastic tray. I don't remember if I had to drill the holes or not but they are space the same distance as the two screws for the metal dogleg are. Once I had the brackets repositioned here from the rear I Goop'd on the carbon fiber gyro plate to the now repositioned supports. Man I wished I had a camera as a picture would be alot easier. I don't remember if I bought a new CF plate or not but it perfectly fits now with a little cutout that fits the plastic tray.

04-05-2003 Over year old.

Safe_Cracker
Key Veteran
Location: Chicago, IL

daggit..

In that pic isn't that swash on wrong?I always thought the two openings on the swash point to the front and not to the side like that?I could be wrong(just curious).

04-05-2003 Over year old.

Billme
Key Veteran
Location: MS

Thats where I mounted mine Daggit...It should work good there...
BTW, I had the 9253 go out, only lasted 2 months after the warrenty..
I'm currently running a 94757 airtronics right now...So far, so good...
Good luck,
Bill

04-05-2003 Over year old.

daggit
Elite Veteran
Location: Waseca MN

Safe_Cracker

I don't remember how I wound up with the notches on the side but the holes are all 90 degrees from one another so I suspect it makes no difference.

Only reason I can see that there are only 2 notches instead of 4 is cause there are a couple mounting holes where the other 2 notches would be... maybe for CCPM applications? I don't know anything about CCPM.

Thanks for the reassurance Billme , I'm questionaing everything right now and the snowfall is delaying my progress!!

I had a 9253 go out too on my Raptor... but i suspect my 40mph collision with the ground may have had something to do with that

(refer to post: digging for worms with Raptor )

.

04-05-2003 Over year old.

HOMEPAGE

daggit
Elite Veteran
Location: Waseca MN

Ok, I'm stumped...

The wag is DEFINATELY due to inconsistent engine speed

At first I thought it was the gyro, but the engine is obvioulsy causing it now (condition worsened) ..

My motor will NOT maintain a constant speed. 4 weeks ago I test flew this heli after installing the new 603 carb and it ran great.

I have tried every needle setting... no settings improved it, though I could make it worse when the needle was way off.

Then I re-checked to be sure the carb hadn't worked loose, went through the fuel system, tubes, tank, filters, tried new spark plug. Checked head bolts and muffler bolts. Nothing changes the missing.

What am I missing?

04-12-2003 Over year old.

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Billme
Key Veteran
Location: MS

ok, What are your atv's on pitch, and throttle, high, and low on both?

What is your pitch range, and how much pitch at hover, with what blades?

What radio do you use, and what does your throttle curve look like?

Whats the lenght of your servo arm compared to the carb arm....

Usually, to much throttle movement during hover can cause this...

One important note is that if you have been running the engine with the lowend lean for a long time before trying this setup, the rings can not seat properly...Some take a little longer, some don't seat at all..
It may take a couple of gallons for the engine to settle out..
How much fuel have you burned since doing this setup?

Second note is, you might not be running enough load on the engine assuming all else is ok....

Regards,
Bill

04-12-2003 Over year old.

Lee Conner
Heliman
Location: Sinking Spring PA

Daggit, I know you mentioned air filter, but I once had an engine that while at idle would go high then low never staying at a constant RPM.
Rather then going into all the boring details, after replacing the air filter all was good.

04-12-2003 Over year old.

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