Rotax Gearbox

[fun-flyer]

Hey does anyone know where to get a Rotax 2.58 or 2.62 to 1 C style gearbox.

I curretnly have the 3.0:1 but since I have a space problem and can only swing a 64" prop I need the lower ratio. My engine is the Rotax 618 at 75 h.p. Talking with Warp Dive they say the lower ratio would be better for this diameter prop.

Okay all take care and stay safe.

Grego

[Chuck Irby]

Grego, what machine do you have the 618 on?

[quadrirotor]

you can change the gears:
http://www.leadingedge-airfoils.com/RTXPARTS.HTM

[fun-flyer]

Good morning Chuck,
I am building a drop keel CLT machine with a little of many designs and some of my own. Dominator, Air Command, Mad Max etc. I'll try and get some updated photos on my web site. Now back to the garage and working on the engine installation.
Grego

[Chuck Irby]

I asked because I have a 618 Dominator with a 60" 3 blade Warp Drive and a 3 to 1 gearbox. My opinion, is that you will be well pleased with the 3 to 1, especially with the 64" prop.

You should be able to run as fast as you want to with a 3 blade Warp. My machine will do 100 mph and cruise at 70 to 80 with no problem. Let me know what you decide to do and if I can be of any help, just let me know.

[fun-flyer]

Chuck,
I think that is the same prop Scott is flying on his Dominator and his performance is also very good. He too has a 618 with the 3:1 ratio.

I watched him do a short field takeoff into a pretty good head wind one day and it was very impressive. He setup as far back on our taxi as he could because the wind was a direct cross to the runway, ran the blades up and when the nose came up he poured on the coal. He was off the ground in about 80 feet and by the time he reached the other side of the run (about another 200') he was easily at 200' agl +. The wind was probably blowing at 20 mph gusting to 25. Talk about pump you up to get busy building that will do it.

I'm going by what the guys at Warp Drive told me. They suggested a four blade prop, or lower the reduction to get the full power the engine will produce to the prop. I somewhat agree because if you look at the prop RPM with the engine at full power (7200) with a 3:1 ratio the prop will be turning 2400 RPM's. A 64" prop can turn somewhere in the nieghborhood of 2800-3200 rpm. With a 2.62 ratio and 7200 RPM full power the prop RPM is about 2748. Close enough for me.

I could get the gears changed and it would probably be cheaper. I haven't completely made up my mind to make the switch. So I'll continue getting the feedback from you guys and then make a decision.

Thanks for the input, NOW back to work
Grego