Crown and Bevel Gear

[Romeo RL67]

Originally Posted by Romeo RL67

I machined a new component and cut/modified the crown gear to fit.
Attachment 494465

Attachment 494466

Reverse the pinion block and the front tail holder. I have to cut the tail and the torque tube to retain the original length.

[BenScoobert]

Originally Posted by Romeo RL67

I machined a new component and cut/modified the crown gear to fit.
Attachment 494465

Attachment 494466

After all that effort I hope it works for you!!

[Romeo RL67]

Originally Posted by BenScoobert

After all that effort I hope it works for you!!

I flew it twice now, Ben. But havent pushed it hard.

[Romeo RL67]

I just loved this heli so much but I do not have the peace of mind flying it with the original crown gear. Too bad I can only do this on the Faifa because the main gear is wide enough. I can release the CAD drawing so that other srimokers can get this made by their local machine shop.

[Varelco]

Yes please Romeo If you could send over those CAD drawings that would be great

[Joe Bailey]

Originally Posted by Romeo RL67

I just loved this heli so much but I do not have the peace of mind flying it with the original crown gear. Too bad I can only do this on the Faifa because the main gear is wide enough. I can release the CAD drawing so that other srimokers can get this made by their local machine shop.

I'm building mine at the moment and I don't think all the blame lies on the crown gear. Just looking and setting up the tail take off mesh shows some flaws in the bevel gear support block design. There's only two bolts supporting it and the holes they go into are huge producing a very sloppy fit. The only thing stopping the block from twisting and rotating in flight is the friction produced by those two bolts. A third support bolt position further forward would help a lot in reducing the twist on this block. A third support bearing in the lower bearing block would be even better.

I haven't flown it yet but I've used a lot of MA helis with crown gears and there design is pretty bullet proof but its very differant to Kasamas design.

[Romeo RL67]

Originally Posted by Varelco

Yes please Romeo If you could send over those CAD drawings that would be great

Crown gear adpter.pdf

[BenScoobert]

Originally Posted by Joe Bailey

I'm building mine at the moment and I don't think all the blame lies on the crown gear. Just looking and setting up the tail take off mesh shows some flaws in the bevel gear support block design. There's only two bolts supporting it and the holes they go into are huge producing a very sloppy fit. The only thing stopping the block from twisting and rotating in flight is the friction produced by those two bolts. A third support bolt position further forward would help a lot in reducing the twist on this block. A third support bearing in the lower bearing block would be even better.

I haven't flown it yet but I've used a lot of MA helis with crown gears and there design is pretty bullet proof but its very differant to Kasamas design.

I've never had any show signs of movement post flight.

[Romeo RL67]

Originally Posted by BenScoobert

I've never had any show signs of movement post flight.

Me either.
I believe all helis have their own limitation and I have reached the tail limit on this heli.
Just like the TDR, they have reached the RPM limit so they are building a bigger drivetrain TDR/TDS.

[wadders248]

Originally Posted by Romeo RL67

I'm afraid will get a tail blow out. I guess we need to do an inverted hurricane with that set up and see if the tail blows out.

Backwards full pitch circuits, speed run to sideways loops and very hard-stop tail down were all fine with the reduced tail pitch. Not even a hint of tail blowout.

I flew the same manoeuvres two days before, without reducing the tail pitch and stripped the teeth in three different spots on the crown. I'm also only running 95mm tails, though the head speed is 2200rpm.

With the amount of tail pitch at full travel, the tail blades are stalling the drive train.

[Varelco]

So exactly how much is the travel being reduced by? I plan to run to a headspeed of 1900 and lower on 105 tails.

[BenScoobert]

Originally Posted by Varelco

So exactly how much is the travel being reduced by? I plan to run to a headspeed of 1900 and lower on 105 tails.

Wadders did approximately half, about 20° each way.

[Romeo RL67]

Originally Posted by wadders248

Backwards full pitch circuits, speed run to sideways loops and very hard-stop tail down were all fine with the reduced tail pitch. Not even a hint of tail blowout.

I flew the same manoeuvres two days before, without reducing the tail pitch and stripped the teeth in three different spots on the crown. I'm also only running 95mm tails, though the head speed is 2200rpm.

With the amount of tail pitch at full travel, the tail blades are stalling the drive train.

Well this is a good news then, cause I have the classic Srimok and Dune that I cant apply this mod.

[BenScoobert]

Originally Posted by Romeo RL67

Well this is a good news then, cause I have the classic Srimok and Dune that I cant apply this mod.

It's not a mod, it is a setting in your FBL unit or gyro, just reduce tail throw limits

[Romeo RL67]

Originally Posted by BenScoobert

It's not a mod, it is a setting in your FBL unit or gyro, just reduce tail throw limits

I meant, my KDS mod.

[wadders248]

Originally Posted by Romeo RL67

Well this is a good news then, cause I have the classic Srimok and Dune that I cant apply this mod.

Fantastic mod by the way... it would still be good to have the option from Kasama to have helical tail crown and gear, but at least reducing the tail pitch gives a solution for people who want to use stock parts.

[Y@nkee]

I would like to get the helical stuff on mine to, but atm i not having problems with the stock parts, mine used to eat the bevelgears in 5-6 flights , even if i had the mesh tight or loose, my pinion had pretty sharp edges.
So, i pulled it out and went over each tooth with a small file to dull the edges some, put it back in with a new bevelgear and set the mesh pretty tight. Havent seen a speck of white dust from the bevelgear after that.

[Romeo RL67]

This heli is worry free now to my skill level. Had more than 30 flight on it now without any lubricat on the bevel gears.

I have 1 extra of this mod. PM me if you need it. This will include the modded gear and the machined adapter, no screws included. You will have to buy the other matching bevel gear.

[George J]

Originally Posted by BenScoobert

It's not a mod, it is a setting in your FBL unit or gyro, just reduce tail throw limits

I've just reduced my throw mechanically by moving the servo ball in a hole after stripping a second crown gear in as many days!! Yesterday was with 105's on and full throw and today was with 95's but was doing a vbar optimization so full rudder and hard stop etc etc. Have to say its going to take a few flights to get confident with it again although I've had a Faifa before and had zero issues with the crown.

Is there any chance one of you fine people could measure the distance you're getting between the tail gearbox now you've reduced the throw/pitch? I think I've reduced the throw by around 4/5mm, that sound about right?

I'd certainly buy any upgrade that became available.

[BenScoobert]

I've reduced mine to 20 and 25 degrees. I say there smacking the tail left and right for a whole flight to test it. I find it hard to believe anyone could strip a crown at these amounts. Tail held perfect too.

Originally Posted by jonesheli

I've just reduced my throw mechanically by moving the servo ball in a hole after stripping a second crown gear in as many days!! Yesterday was with 105's on and full throw and today was with 95's but was doing a vbar optimization so full rudder and hard stop etc etc. Have to say its going to take a few flights to get confident with it again although I've had a Faifa before and had zero issues with the crown.

Is there any chance one of you fine people could measure the distance you're getting between the tail gearbox now you've reduced the throw/pitch? I think I've reduced the throw by around 4/5mm, that sound about right?

I'd certainly buy any upgrade that became available.