My high HP starter motor pre rotator

Aussie_Paul · 09-06-2007, 09:29 PM

You may recall a couple of years ago I tried a specialist starter from the custom hot rod capital of Oz, Castlemaine, just up the road from me at. I used it once back then to spin 30' RAF blades up to 170 rrpm BUT nearly shore the ring gear rivets off.

Meanwhile I have been waiting for a number of people to come up with a suitable soft start.

Yesterday I did 3 pre rotations and flights with this 50% more powerful, 20% heavier starter, and my prototype soft start. The first time I had the engine idling and put the soft start in for the same time as I do for the Rosco starter. When I hit the full voltage the engine stalled due to either the alternator working extra hard or the voltage dropping below what the ecu will handle. At this time I believe it was the alternator.

Next time I had the engine at 2000 rpm and left the soft start in the same time. This was almost ok but the full voltage did produce a fair amount of torque on the mast. The 3rd time I had the engine at 2000 rpm but left the soft start in 50% longer and the transition was quite smooth. I am not sure how hot the wire resister became as I can not see it from the cockpit. I could not smell anything!!

I did not have a rotor tach fitted but the blades were almost a blur. I started the take off run and as the nose wheel lifted I switched the pre rotator back on and it wanted to keep driving.

I will try shortening the stainless welding rod resister a couple of inches and see if that fine tunes it enough. The soft start is actually too soft with the amount of stainless welding rod I have as the resister.

Worst case scenario would be a 3 stage with another solenoid. The soft start could have the longest wire resister, the second half that length and then full voltage. I do believe that the 2 stage will be able to be fine tuned but time will have to tell.

Anyway I was extremely happy with the results.

I can't wait until a calm day for further tests.

Aussie Paul.

niquenaque · 09-06-2007, 10:05 PM

Hmmm,

How are you doing these stages Paul??

No doubt you would be and I hope in parallel, because if you switch them on individually you might well end up with a welding rod doing just that, complete with sparks and molten metal.

I hope you have attempted to find out at what point the wire will melt with a 12v power supply..

Cheers,

Nick.