DesignMan

I need to be able to start my diesel without touching the compression or needle setting. The reason for this is that in Control-Line aerobatic competition, you are strictly limited on your run time, and can't use a shutoff timer or servo. You have to achieve really consistent runs with just the load of fuel in your tank.

How do you get the engine started and up to temp. without touching either the compression or needle?

gcb

Larry,

One opinion:

Some have success using a venturi choke (no extra prime) on an inverted engine. Only practice will reveal how much to choke it. You might want to use a glove while you are learning the correct procedure...but you already know this.

It should warm up during take off and level flight.

George

maxtenet

Once mine are set and broken in I don't touch either setting. However, I use an electic starter (don't do this unless you are an experienced diesel user as hydraulic lock will bend the connecting rod if set too rich!, trust me, I know from experience!)and they have to burble and spit for about a minute until warmed up before use. They need higher compression for starting and less once warmed up. If you don't have warmup time you're out of luck. You might want to run it a few minutes before competition to warm it up some. Can you use an electric starter? Hot hand starts can be difficult as well. Experience is the only way to get it right. I have been running the things for 30 years and still have an occasional problem getting things to start quickly.

Max

dennis

My Feedback: (90)

Larry, your an experienced diesel user and I'm sure that you know pretty much what to do. But treat your stunt plane as a team racer and prerun the motor if you can and have it hot when you get to the line. This necessitated that you have the motor ready to go asap so you don't lose the heat.
I always used a starter on mine to get the motor going initially,do not prime more then one turn through of the prop just to lubricate the motor.If it's a 1/2A then a half flip of the prop, Usually they will go off immediately. God how I hate that stunt image of the one flip start like your manhood is tied up in achieving that idiotic ritual, just to impress the judges.
Your biggest problem is how to control the run. To achieve consistancy I use a cooler and a few ice packs to keep the fuel cool. Do not let your fuel get warm your run time will seriously vary from tank to tank if you do. Do not let your fuel sit in your tank and warm up or you could have an overrun.
In R.C. I had it easy controlling my runs and I always ran my tank out and could guess to within 15 seconds on shutoff.
I love diesel motors but I seriously don't think that if I was going to compete P.A that I'd use one, even though I really like the run that a properly set up diesel will deliver. A consistant speed throught the flight with no speed up on the downhill is really something to behold. Of course the way that my glow's have been running recently in the circle I'm really starting to consider it again. Stinking up my new car is the limiting factor. Yea I know about lamp oil .scent too.
Oh and on another note I have my pre revilite Norvel with a texas timer mount instaled in the Hyper Viper #2, with a Davis head and waiting to fly it.
#1 is flying glow with the same set up, gotta tell you it beats the Cox product motor and is a lot less effort then fitting up a custom Cox. Only needed to space the motor to fit. Dennis

Jim Thomerson

I am in agreement with not changing the needle or compression from the running setting. One may not be able to accomplish this with all diesels. I have found that I can do it with ST G20-15's and dieselized Tower 40. It is possible to hand start both but I use an electric starter. Basically running settings are generally lower compression and leaner than what you would set for optimum hand starting. So with care, the possibility of hydraulic lock is remote. I have used the 'finger over the venturi choke' after the engine starts, usually needed for just a couple of seconds. John McCollum suggested using a piece of removable fuel tubing stuck in the venturi. Sounds good, but I have not tried it.

With these engines, I do not do a prewarmup. If the engine immediately starts singing, it is probably overcompressed. I like for the engine to sound undercompressed about until I get ready to release the airplane. If it burps a few times during the initial level laps, no harm is done.

Jim

dennis

My Feedback: (90)

Jim, Your quite correct in your remarks, I should have separated my electric start and hand start remarks. Sorry for the confusion. Dennis

DesignMan

Thanks guys. The TT/DDD engine I am playing with still has its RC carb, so it will be easy to rig a starting and running 2-position linkage. Much safer than sticking your finger near the prop with the engine running.

I suppose it will get more tractable as it runs more. It has less than an hour on it, first as glow, then converted. Also, I have been switching props to get rpm data, and now will settle on what I think will be the best to use ( 8.5 x 6 should do it, I run a Rev-up 7 x 5 on my MP-Jet .061). I want to aim for around 11,500 rpm, flying on 60' lines (.008 solids are legal!).