Raptor 50v2 Strange Problem

[johnnyc]

Hello,

I have been flying a Raptor 50v2 this season. I got the bird used so really don't know the history.

Just recently I have been having problems in normal mode at about 50-55% throttle. It seems that there are instantaneous losses of power and it happens every couple of seconds. The engine is fine and never loses its note. The pulsations cause the tail to quickly kick out but it comes back. The problem can be seen and heard.

There is no problem at idle-up mode with 65% power. It only happens in normal mode.

I took out the clutch and it looked fine, but I am a newbie and don't really know what to look for. I cleaned it and reinstalled. The heli was fine on take off and then back to the jitters.

Should I put in a new clutch, or is something else, like a bearing, to blame? All belts and gears look fine. Tail spins freely.

Thanks for your help! :D

JC

[raptor_4_me]

The engine is fine and never loses its note

then you said
The problem can be seen and heard

hmm can you hear the engine come down off rpm's? what is it that you hear?

[Rodan]

Is it going in and out of failsafe?

[johnnyc]

The engine is fine and never loses its note

then you said
The problem can be seen and heard

hmm can you hear the engine come down off rpm's? what is it that you hear?

Engine seems to be fine. It is tough to describe, but it is like someone is slapping the tail sideways 2-4 inches. This is not an oscilation like too high gain on gyro. Just a slap in the tail every couple of seconds. Not there in idle-up, only normal mode at lower rpm.

Does this sound like a clutch slipping and losing rpm? Or a bearing "catching" and slowing the tail down instantaneously?

Thanks,

JC

[johnnyc]

Is it going in and out of failsafe?

I don't think so. If I go to idle-up mode, problem is gone. Only apparent at lower rpm flight in normal mode. So I don't think that it is a radio or gyro/electronics problem. Sounds mechanical.

The tail jerking happens every couple of seconds. It is like someone is slapping tail sideways a few inches and then tail/gyro fights it back. Not an oscillation.

Could it be a tail rotor bearing "catching" and instantaneously slowing the tail rotor? or is this a symtom of a clutch catching and releasing?

JC

[Motions]

Sounds very much like engine tuning. Are you sure the engine perfectly tuned?

Also, what pipe are you using? If your using a MP that will cause this scenario at low speeds too.

[Bayou Talker]

Also what is your head speed in normal? 50-55% seems low.

[Maxx26]

I have a cy pipe on a 50 hyper and when it is too lean on the high speed it dose that.

[johnnyc]

Sounds very much like engine tuning. Are you sure the engine perfectly tuned?

Also, what pipe are you using? If your using a MP that will cause this scenario at low speeds too.

I am using the stock pipe and the TT 50 motor that comes with the kit. I did change fuel/plug recently. I had been using 15% and switched to 30%. I also just put in an OS #A3 glow plug.

I know that my top end mixture is good and rich - I played with that. Maybe my low-end is too lean and I have a lean mid-range? Are you thinking that this is pre-detonation? Is 30% too much for the TT engine? Is the plug too hot?

Thanks,

JC

[johnnyc]

Also what is your head speed in normal? 50-55% seems low.

Hello,

I don't know what the head speed is. I set up throttle/pitch by the manual. Don't know how to measure head speed?

Problem only appears when at the reduced throttle setting in normal mode.

JC

[johnnyc]

I have a cy pipe on a 50 hyper and when it is too lean on the high speed it dose that.

I set up the high-end and it is definately rich on purpose. Maybe I have a lean mid-range and should back out low end needle?

JC

[Motions]

First and most importantly, you need to tach the head speed before you do anything else. If your new to helis, there's no way your going to be able to guess what the head speed is. There's really no need to troubleshoot an engine problem if your nowhere near the proper head speed.

Next, the low end needle on the TT engine controls the low end and most of the midrange tuning. If your hovering, with proper head speed, then the low end needle should be fine tuned.

Personally, I wouldn't put it back in the air until you tach your head speed.

[johnnyc]

First and most importantly, you need to tach the head speed before you do anything else. If your new to helis, there's no way your going to be able to guess what the head speed is. There's really no need to troubleshoot an engine problem if your nowhere near the proper head speed.

Next, the low end needle on the TT engine controls the low end and most of the midrange tuning. If your hovering, with proper head speed, then the low end needle should be fine tuned.

Personally, I wouldn't put it back in the air until you tach your head speed.

I have an airplane tach. Can I use that for checking headspeed? How do you do it?

JC

[shall36]

[/quote]

I have an airplane tach. Can I use that for checking headspeed? How do you do it?

JC[/quote]

Very carefully...
What I've done is get things spooled up and set the collective stick to about where there bird wants to lift off. Using the pitch control trim knob, I dial out some pitch (move the collective trim slightly negative relative to collective stick position). This keeps the bird from lifting (I wouldn't do this on a windy day!).

Then, I move in only as close as needed to get the tach pointed from the top down at the edge of the blade.

Obviously, this can be very dangerous. A sudden gust of wind could cause the bird to lift...an accidental bump of the collective or cyclic could cause the bird to fly into you. Be careful. But once you know what XXXX RPM sounds like, you can guess the rest from there.

[Rodan]

Find someone with a heli tach or buy one. It's really a necessary tool to have anyway, and trying to use an airplane tach is just going to be dangerous. You really need to check your HS in hover, anyway...

[Bayou Talker]

While the airplane tach might seem to work, the angle and proximity to the blades can give false results. It is definitely better and safer to purchase a good heli tach. It is something that you will have a need for as long as you are in the hobby.

http://www.deeteeenterprises.com/NS.Tool.Sky.Tach.php

This is the one that I use and it does fine for me.

[johnnyc]

First and most importantly, you need to tach the head speed before you do anything else. If your new to helis, there's no way your going to be able to guess what the head speed is. There's really no need to troubleshoot an engine problem if your nowhere near the proper head speed.

Next, the low end needle on the TT engine controls the low end and most of the midrange tuning. If your hovering, with proper head speed, then the low end needle should be fine tuned.

Personally, I wouldn't put it back in the air until you tach your head speed.

You were right. It was an engine tuning problem. Seems low end was really lean and was affecting mid-range mixture and causing pinging. I richened low end needle and problem went away. I am still lost on the tuning, though. The main needle is 3.25 out, haven't checked postion of low end. Seems high-end should be near 2.5 out.

JC