Red Bull Main Drive Mechanics
For this build I am using SAB Goblin 500 mechanics. I selected them because they are beautifully designed, small and compact. I would have bought these from Peter Wales of Florida, but he was not going to do this small size. So I decided to do my own design. Of course it will look allot like Peter's, but then again there is not much I would do differently.
I have gone through a couple different mounting ideas though. I was going to use two vertical mounts that would connect to the side and then bolt down from the bottom. Then I decided to just use a simple L-bracket. Very easy to make and plenty strong enough for the task at hand. I may end up redoing the L-bracket design once also. My initial idea was to use a Trex600 torque tube drive transmission, but then, just like Peter's design, I decided to make some bearing blocks and use a belt drive to torque tube transmission setup. Certainly not a new idea, but it should work very well. You will see this below.
So this was my first idea to use the Trex600 torque tube drive setup. You can also see the
the front vertical mount along with Y-bracket.
Then I went with a simpler L-bracket design. Partly because I needed a
way to mount the torque tube drive system, and because I thinks it's better.
Test fit with some weight reduction on the rear section also.
New longer secondary shaft to accommodate the small pulley
which will be used for the tail drive input.
New secondary shaft installed. I actually made the shaft from a Trex500 main shaft.
One way bearing/pulley installed and ready for the tail drive pulley to be installed.
This is the bearing block I made for the tail drive transmissions vertical shaft.
Tail drive pulley, tail transmission pulley, and belt all in place. You can see I have just
clamped the lower bearing block in place for now. Will drill mounting holes next.
Now I am machining a slot to allow for belt tension adjusting. I am doing this so
that I can use different pulley ratios if needed. Won't know this until some testing is done.
Lower bearing block secured in place. You can see I need to work on my machining skills as
the block is a bit smaller than the slot in goes into. Not how I wanted it to look, but it will work.
I also had to drill out the metal gear to fit a 6mm shaft. The kit came with metal gears for driving the tail rotor.
Here I am drilling out the (+) drive on the gear to accept a 5mm or 6mm shaft. Once I am able to
use the shaft I have many more options available for connecting one end to the other.
Next I made a bearing block to hold the umbrella gear that will drive the
tail rotor drive shaft.
Here you can see both umbrella gears installed in place. I designed this transmission so
that the gear on the vertical shaft can be mounted with teeth on the top or bottom. This allows
me to select CW or CCW tail rotor rotation. The driven gear height is also adjustable to allow for
some alignment with the tail boom and tail rotor drive shaft. I think this system will work very good.
And here you can see the shaft that will connect to what ever couple I choose.
I plan to use dog bone couplers on this end. They will allow for some amount of
angle from this shaft to the tail rotor drive shaft, just like a car or truck do.