Blades not spinning...

[Cralis]

AHA!

Right, check this!

I noticed the last thing the guy did that helped me change the main shaft, was he seemed to say that the pinion (right name for the gear on the engine?) was too far from the main gear. It seemed right to me, as I watched the finless stuff.

But he's been flying for 2 years, so I thought he must be right.

Anyway, he worked on it while I was packing away my tools.

I now notice that when I spin the blades, it loosens at a certain point, the tightens. But now that I have typed this, the cogs seem to spin freely again! What the hell!?

OK, my thought is that either the engine pinion is too close to the main gear.. OR... the engine is loose and moving back and forth?

[jimbob]

re-set the motor position to set the pinion to main gear mesh.

Theres plenty of methods and discussions about how to do it, so i wont write it all again - search for pinion mesh and you should find it ok.

Also check that the tail drive belt isnt twisted 360' - I run mine a lot looser than you might think was wise, as too tight a belt will sap motor power considerably.

Check out TRex Tuning for lots of other good advice.

[Cralis]

Damn this. The wheels were spinning well. So went for another hover. 45 seconds, and stable! But then it seemed I need to put more throttle to maintain the hover. Then it seemed to be glitching, but it was more the tail seemed to twitch. So I sat down and once again, blades seem to not spin freely again!

[Philimon]

Perhaps I'm stabbing in the dark, but it sounds like something is getting warm and then siezing up. Perhaps the motor or a bearing?

I'm new to this too, so maybe I'm talking through my nose.

[Nutz]

When it gets stiff, pop the belt off and see if the tail is stiff or the main gears.

You need to find what is causing the stiffness by process of logic. The main blue gears are not the roundest so when meshing do it at the tightest spot.

Things that could cause the stiffness on the head/motor/maingear are bearings, motor mesh, swash problems binding or swash bearing. The oneway bearings in the maingear will cause stiffness from the motor as the motor will induce drag when there is no power is going to it.

The main gear should only turn freely in a clockwise direction by it self, it may feel notchy depending on what motor is connected to it.

Things that could cause the stiffness on the tail section are reducer gear bearings (that tail belt attach's to), belt being over tightened, tail bearings or tail slider problems (if the tail slider is out to far or in too near by the gearbox it may bind.

Expect to see less free wheeling of the main blades the tighter you have the tail belt as this will take a little energy away form the drive system.

Hope this info helps you mate.

[ChrisB]

Agree with all that,if you cannot find a cause i would suggest you check the motor pinion is secure to the motor,re mesh the motor pinion to the main gear,check all the teeth,remove the boom and ensure the belt is not twisted etc

There is something going on here and it may need some dis assembly to find the cause

keep us posted

[Cralis]

OK, I have got the belt off the little gear that it goes around at the base of the fuselage. The tail rotor now spins freely. I spin it, and it continues for a long time.

If I spin the main rotors, they spin freely too, clockwise. Anti clockwise, they stick a bit, but that's the engine, I think.

I then reattach the belt.

When I spin it, it's not spinning freely again. I notice that the tighter I pull the tail boom, making the belt tighter, the harder it is to spin. Not much, but it is changing.

If I leave it so that the I can squeeze the belts together, it's easier to turn. But I think the belt is supposed to be so tight that you can get them to touch?

So far, it looks like the tail isspinning freely, as is the main rotors, until I attach the belt. Then it gets a bit tougher.

[ChrisB]

Is the belt twisted incorrectly,this would add a lot of drag

[Cralis]

I wanted to check that, but not sure how to do it.
I have now replaced the belt, and I think it slighly less tight than it should be, as I can wiggle them a bit, but it seems the tail and rotos are now spinning freely.

[Nutz]

The belt should twists 90° in the boom, it is quite easy to put 270° twist to it which would make it rub in the boom. If you look down the tail and shine a light through the other end you may be able to see it (it is quite hard to visually see).
Or you will have to remove the boom with belt and check.

[Cralis]

Thing is, it's spinning well now. I'd have thought if the belt was twisted, it would be causing the problem all the time. I have the blades back on now, and it seems like new. I think the belt was too tight. There's a heli guy nearby that is going to get me some fuel. I'll take the Trex and ask him to see if it's too tight. It's hard to explain tightness on the forums, I guess.

It's pouring with rain up here, so can't test it. The grass was wet yesterday when I was trying to fly. Could that be a factor? Something getting wet?

[Leebert]

Try using a small screwdriver.
Hold the end of the handle with your fingertips (so you can't grip it really tightly but you can hold it ok) and push on the side of the belt between the boom and the drive pinion. You should be able to push it just over half way across to the other side.

You only want to measure the belt using "moderate" pressure and holding the screwdriver by the end means you can't put much pressure on it if you see what I mean.

Try looking at Finless Bob videos on the net: http://www.helifreak.com/viewforum.php?f=95
There may be a video there that answers your questions.

Best of luck and I hope the weather cheers up so you can test it

[Cralis]

Did that, and yes, it goes half way-ish. Using my fingers, I can push it all the way across. So it looks like the tension might be right now.

Light drizzle now, and brighter sky, but VERY wet garden... I'll get the hair dryer and an extention out.

Which reminds me, at cricket matches in South Africa that I used to go watch, (internationals) if it rained, you'd have to abandon play, but if it was a light rain, and the pitch got a bit wet, and the rain cleared, you'd have a wet pitch, which you can't really play cricket on.

So they would call in the helicopter which would hover over the pitch and assist the drying process.

Used to be good fun watching it hover and dry the ground in front of us. Pilot had pressure... Only 25,000 people watching him. Cheering...