clutch/liner gap from the factory

[jmdanna]

I just finished building my N5c yesterday and everything looked fine while putting it together but I am having problems spooling up with the Brain governor. The engine starts to rev up but the blades don't start spinning until the governor is about to engage, and since the rpm is too low, the governor does not engage.

I am wondering if the gap between the clutch and the liner was set incorrectly at the factory? Has this ever happened before in a new kit?

If this sounds like a defective clutch, would Synergy send me a new clutch assembly under warranty?

[cml001]

When I was using ikon.. I had forgot to uncheck the box for electric models... Double check that.

[LWilliams1214]

I have a stupid question and I'm sure you checked for this but. Is it possible that your engine started in reverse? I've had this happen to me a few times and has always made me think something was wrong.

[jmdanna]

The electric box was left unchecked.
The engine did not start in reverse. I have had that happen with my Fury 55 but this was different. The blades would start spinning but not nearly fast enough.

I will switch the governor off and use a throttle curve and see if the blades spool up like normal or if the clutch looks bad. I will take a video so you all can see.

[jmdanna]

So I went out to test it without governor enabled. These were the throttle curves I found online. Fairly low headspeed but enough to prove the point.
Normal: 11-28-45-60-75
Idle 1: 80-65-55-65-80
Idle 2: 85-70-55-70-80

Here is the video of the test. A very mild flight as I am not comfortable with the clutch or these throttle curves.

For reference I have made a table of contents of what I remember from the flight after replaying it.
0:00 - I start feathering the throttle.
0:29 - Clutch finally grabs, at about 50% throttle.
1:00 - I switch into Idle 1.
1:42 - I switch into Idle 2.
1:53 - Seemed to start overspeeding a little bit.
2:06 - Not comfortable with the increase in headspeed I switch back to Idle 1, and it goes back down.
2:45 - Huge increase in headspeed with no change in throttle input, so I give it ten seconds to come back down and it does not, so I auto down.

! No longer available

Not only am I fairly certain the clutch or liner is bad, but I am a little worried about the jump in headspeed at 2:45. Is that what happens when an engine goes lean? My high needle is at 1 3/4 plus 2 clicks, and mid needle at 1 7/8. I am running rich to start with, but that does not sound good to me.

[Chris Sexton]

The rpm change at 2:45 could just be the engine is loading up from being rich and struggling to get to rpm.

It does seem like it's taking too long for the clutch to engage. I would take the stack off and inspect the parts.


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[jmdanna]

So would that mean the engine was running at a slower headspeed than normal (like drowning in fuel)  until 2:45 where it finally caught back up? I am not particularly experienced with nitro engines and still learning as I go so I really appreciate the advice and feedback.

[jmdanna]

Well, they look okay to me. I even used my calipers and measured inner and outer diameter. It's pretty close, i don't understand why the engine is behaving this way?



Bell ID - 41.87mm
Clutch OD at the base of the shoe - 41.26mm
Clutch OD at the middle of the shoe - 41.16mm

So it seems like each shoe only has to expand about 0.3 - 0.35mm in order to contact the liner. Does that sound right?

[LWilliams1214]

If possible can you check your clutch hub to make sure it's completely seated and tightened on the end of the crankshaft? The clutch h and clutch bell look fine to me from what I can tell in the pictures.

[jmdanna]

When the engine was out of the heli I tried inserting the crank lock tool and rotating the fan hub. I didn't want to try to break it so I didn't wrench on it, but it did not rotate with a decent amount of force.

[jmdanna]

Well from what I have read online, it seems this gap is too large. On to order another liner...

Which one should I get? I am hesitant to order another stock liner because it will probably be too thin again. Is the N7 liner thicker or should I go with a 700N liner or something else?

[Rodney Kirstine]

I am wondering if the gap between the clutch and the liner was set incorrectly at the factory? Has this ever happened before in a new kit?

I can't recall anyone ever posting about having an issue with the stock liner in a brand new Synergy clutch bell.  Of course, that doesn't mean there can't be a first time. 

If this sounds like a defective clutch, would Synergy send me a new clutch assembly under warranty?

Matt always takes care of problems, for sure, on defective parts.

Which one should I get? I am hesitant to order another stock liner because it will probably be too thin again. Is the N7 liner thicker or should I go with a 700N liner or something else?

I've got over 1,000 flights between my N5C and N7, all on Synergy clutch liners and my flight count is quite a bit lower than a lot of the team guys. The N7 liner is the same material, BTW. 

Are you sure there's not something else going on, like the one-way bearing slipping?

[jmdanna]

The N7 liner is the same material, BTW. 

Are you sure there's not something else going on, like the one-way bearing slipping?

So the N7 liner is no thicker than the N5c liner?

I just checked the OWB and cannot get it to slip by hand. I don't think it's that. I don't know what else it could be besides the clutch?

[LWilliams1214]

The one way bearing hub can go on the main gear in any direction. Maybe the hub is upside down? If you hold the auto gear and try to rotate the main gear clockwise it should lock up. If you hold the auto gear and rotate the main gear counter clockwise the main gear should free wheel. If that's the case you'll just need to flip the main gear and hub upside down. Not questioning your building skill just trying help get this bird in the air .

[jmdanna]

No worries, but yeah the OWB is in right. Using throttle curves I am able to get the bird in the air, but it takes an unusually long time for the blades to start spinning. The blades don't start spinning until mid stick, which is set at 50% throttle.

This makes my Brain governor have trouble spooling up, and it usually fails to do so.

I just tried wrapping my clutch in electrical tape. 1 layer was loose when putting the bell over it. 2 layers made it a snug fit, but I am still able to move/rotate the bell (so not crazy tight).

I also tried slightly leaner tune, and new fuel, to no avail.