DesignMan

I fly CL aerobatics mostly. Now in this event you need totally consistent engine runs. There is an 8 minute time limit including starting, and the pattern can take 6 minutes plus.

I gave up on competing with Diesels because I can't start them at the running settings, and then can never get exactly the same setting of compression. The final straw was a contest where I under-ran (didn't finish all the maneuvers) the first flight and over-ran (more than 8 minutes) the 2nd flight....with the same amount of fuel both flights.

I might give it another try if anyone has suggestions on how to start a diesel AT the run settings.

Hobbsy

My Feedback: (102)

Davis conversions are very good about starting at flying settings, PAW's are not, what engine are you using, Thanks

DesignMan

Actually, i was running a Davis converted OS .25 fp. Don't forget that I am not using the throttle, so we are talking about a wide-open control-line venturi. I am aware that a throttled engine can be started at final settings and then opened up after a short warm up (like the run out to take-off is enough).

Jim Thomerson

Once you get a flight that satisfies you, do not change anything. Leave the running compression alone, leave the needle alone. Choke the engine a couple of times, flip it a couple of times just for fun and to see that there is no hydraulic lock. Now hit it with your starter and hold the starter on until it starts. If it is slow to warm up and wants to die put your finger partially over the intake until it sounds more reliable. (John McColum says put a piece of fuel tubing in the venturi to choke it, then pull it out when running well, good idea.) Walk out to the control handle, put the safety thong on, wiggle the controls a couple of times and give the let go signal. By the time you do all that the engine should be warmed up and running pretty good. It may not be quite warm, but it will get warm during the level laps and you are in business. If the engine should die in the hands of your pit person, the pit person should choke it once and flip it. It will start and run better than before it died. A month from now when you go flying again, do the same thing.

I do my best not to change anything once I get what I want in a flight. I have found that I will need to back compression off a hair from time to time; carbon buildup, I think. Running setting should be fast and smooth in level flight and the same in maneuvers. If the engine slows in maneuvers, it is slightly overcompressed. If it misses in maneuvers, it is a hair lean.

Jim

DesignMan

I like the fuel hose idea! I have a brand new Shark .15 that Tim Meek built and gave to me. I have a number of .10 through .15 size diesels I would like to use on it. Tim made universal mounts, so changing the engine should be no big deal.