Roban AH-1W Cobra 700 Size Scale Helicopter

[sfcfury]

Yea I was thinking of finding a way to push it center (foam etc), in fact I was thinking about putting some extra foam/dampening material before the elbow as well. The tube caught the notch/nipple that's in the elbow/gearbox. Perhaps i can try to push the mechanics in front to the right lol... not that there's any wiggle room.

[DCORSAIR]

So your whole tail rotor is not off then? In your pic is doesn't look square with the fuselage?

[sfcfury]

I see it; I just don't know where that tilt would come from. You have the nipples that are inside the elbow... on each end. For the long tube side and short tube, and those are aligned. The tail assembly itself is aligned in the pre drilled hole as well.... I'm going to take it apart and double check everything.... *shrug. Clearly it needs some duct tape...

[DCORSAIR]

Okay, didn't know if you seen that is was off, my big 800 has the predrilled hole in the boom as well but its not perfect either, I have to be able to move mine a little to get the vertical T tail straight then tighten the two clamp screws, that screw is on there to hold the tail unit from coming off is all, so on mine, the hole is a little bigger than what it comes from the factory, you might have to do the same to be able to get everything straight and then you will be able to move the tail pitch arm over so the rod doesn't hit the fuselage? I'm sure I will have to do the same on my Magnum Pi version as I did on my AH-6.

[PawPaw]

HELP, y’all! I’m still trying to rationalize this sketchy manual with such a precision machine. Hopefully I’ll get a thumbs up on my guesswork so far:

1. The

[PawPaw]

Oops....hit the wrong button:

1. The tail rotor torque tube “elbow” has a longer end & a shorter end. The grainy pic seems to show the longer leg on the long tube. Is this correct? I had to reverse the linkage triangle to install it this way.

2. My tail rotor hub has 1/2” play back & forth before the torque shaft bevel gear will rotate the main. Is this normal? I can’t imagine one or both of the tail shafts stripped before my motor even arrives.

3. I have what looks like a different design tail rotor shaft bevel gear bearing block & shims from what was installed at the factory. Was in a separate plastic bag. A separate amendment sheet says nothing about replacing the existing bearing block nor a diagram of this part. Ideas?

Thanks for the help!,

[PawPaw]

[DCORSAIR]

Well, I will give it a try on your questions, yes the long side of the elbow goes on the long boom coming from the mechanics, yes you will have a little play in the gears but go through all the gears and make sure you don't have some that are about to skip teeth, a little backlash on the gears is fine, if too tight then you will get excessive wear, and the T looking part in your picture with the bearing in it and those long standoffs are for your motor, if it has a long shaft sticking out past your motor pulley, you add that part to help support the long shaft, if not enough shaft is sticking out past the pulley then that part won't fit and you just leave it off, those washers you see in the bags are shims for the gears and such if you have to tighten up some of the umbrella gears, hope I am right on some of your questions, if not, I'm sorry.

[PawPaw]

Thanks! Makes sense now that you explained everything. I’ve already learned that just because the factory assembled it one way doesn’t guarantee it’s the correct way. The main unit gears are smooth. The slop at the tail rotor hub must be in the elbow itself unless the shaft spline races are wallowed out some.

[DCORSAIR]

Well, if you have backlash in all the umbrella gears and add all that up by the time it gets to the tail, you will have some play, my Bell 212 was the same way so I added a few shims and it still had a lot of play by the time you got to the tail, I would still check all the gears to make sure you don't have one with excessive backlash.

[sfcfury]

First of all... cool that yours came with that motor mount. Mine didn't... and I bought it after market from scaleflying.de. I also plan on getting their gear upgrades; that replace the top two gears that are above the belt gear and motor pinion. I have a touch of slop in mine as well... but some will be taken out of the drive train when you mount the motor/belt. Just be careful to not over tighten the belt, as too much tension will pull the belt gear down ever so slight and it will rub the top of the vertical drive shaft that goes to the tail boom; the spacing between those two gears is minimal. Here's video I found just about a month ago, that will show how to mount the motor bracket and belt tension. It's in German, but it's easy to tell what he's doing and get the idea.

[DCORSAIR]

Here is a picture of how the motor shaft support bracket mounts to my Hughes 500 and a picture of my instruction manual for the Hughes 500-800 size, hope it helps you guys with yours, there is a top and bottom to the bracket, those standoffs fit into little round holes in the bottom of the bracket.

[DCORSAIR]

First of all... cool that yours came with that motor mount. Mine didn't... and I bought it after market from scaleflying.de. I also plan on getting their gear upgrades; that replace the top two gears that are above the belt gear and motor pinion. I have a touch of slop in mine as well... but some will be taken out of the drive train when you mount the motor/belt. Just be careful to not over tighten the belt, as too much tension will pull the belt gear down ever so slight and it will rub the top of the vertical drive shaft that goes to the tail boom; the spacing between those two gears is minimal. Here's video I found just about a month ago, that will show how to mount the motor bracket and belt tension. It's in German, but it's easy to tell what he's doing and get the idea.

Did you get the pkg of shims?, but no support bracket?

[sfcfury]

I didn't get either; I got my kit almost two years ago, when they were still being sold by rc aerodyne... I think they evolved/improved the kit over time... I think the scaleflying de guys had alot of input on those kits.

[sfcfury]

Oops....hit the wrong button:

1. The tail rotor torque tube “elbow” has a longer end & a shorter end. The grainy pic seems to show the longer leg on the long tube. Is this correct? I had to reverse the linkage triangle to install it this way.

2. My tail rotor hub has 1/2” play back & forth before the torque shaft bevel gear will rotate the main. Is this normal? I can’t imagine one or both of the tail shafts stripped before my motor even arrives.

3. I have what looks like a different design tail rotor shaft bevel gear bearing block & shims from what was installed at the factory. Was in a separate plastic bag. A separate amendment sheet says nothing about replacing the existing bearing block nor a diagram of this part. Ideas?

Thanks for the help!,

#3.. You don't have to replace the bearing block; just add one or two of the washer shims to help get the gear mesh as best you can.

[DCORSAIR]

I didn't get either; I got my kit almost two years ago, when they were still being sold by rc aerodyne... I think they evolved/improved the kit over time... I think the scaleflying de guys had alot of input on those kits.

Oh okay, that explains it, yes these newer kits have the helical cut gears already installed, better main shafts, the motor support bearing optional but included, for some reason though my AH-6 has the regular gears but is very quiet, can't wait to see your Cobra flying, it's looking nice.

[F106DeltaDart]

Just got the rotary cannon functional for my Cobra. Ended up building it out of spare parts. The cannon assembly is mounted on 2 Trex 450 bearing blocks and a piece of the main shaft. It is run by a retract motor out an old HobbyKing gear. Works like a charm so far! Next will be adding the pan/tilt system for the turret.

[sfcfury]

Just got the rotary cannon functional for my Cobra. Ended up building it out of spare parts. The cannon assembly is mounted on 2 Trex 450 bearing blocks and a piece of the main shaft. It is run by a retract motor out an old HobbyKing gear. Works like a charm so far! Next will be adding the pan/tilt system for the turret.

Wow looks good.... I would like to see what your going to use to rotate the turret...

[PawPaw]

That cannon looks awesome, F106.
Thanks, sfcfury...it was confusing because the shims were in the same bag as the motor mount. I did notice from pics you posted your frame is different than mine. I was trying to see which holes you used for the tail tube support arms (copycat again) and the hole orientations are different. Not a big deal...
Thanks, DCCORSAIR....my motor arrives today & I think it’s a short shaft. We’ll see.

[sfcfury]

Did you kit come with the helical gears and pinion on top as well? If so, thats awesome! Interesting that your frame is different too... I used the the hole with the metal cross-support tube... and it had a larger and longer bolts in it... so i just figured that had to be where they wanted it to go lol.