A long time modeler, I am new to diesels. I have a PAW 19 that I currently fly and I am forming some opinions based on first hand experiences. I mounted the PAW on a bench mount and spent a good bit of time getting familiar with the differences in diesel operation and breaking in the engine. I then mounted it in an airplane and have flown it a good bit. Here are some of my observations.

After a lot of frustration. I finally got the starting procedures down to where I can start it easily most of the time. The engine likes to start pretty "wet" compared to most glow engines and priming is more difficult since there is no pressure connection to the muffler yet since there is a muffler installed, you can't squirt fuel directly into the cylinder. This requires priming through the intake which creates the possibility if a hydraulic lock if over done. Always turn the prop through by hand several times after priming before attempting to start.

There are two running adjustments that must be made (needle valve and compression) rather than one (needle valve) on a glow engine. The two interact. For instance a leaner mixture requires less compression, and visa-versa. I end up usually setting the mixture, then compression. Usually the compression has to be increased slightly to start a cold engine, and as it warms up the compression is backed off and the needle valve adjusted, then the compression adjusted again slightly. Idle then must be checked. As the engine cools down during idling, and the throttle is again opened, it may be under compressed momentarily causing a little burp. As it warms up again it smooths out. It is possible to find settings that results in a smooth idle, good transitioning, and good high speed performance, but it takes a little fiddling.

Diesels stink. I don't mean the fuel. I rather like the smell of kerosene and ether. However the exhaust residue is dark brown/black and smells like an 18 wheeler thats wet stacking. It is also messy. After installing the PAW in my nice new orange airplane and watching the black oil completely cover the right wing I was ready to give up. Instead I fabricated an exhaust tail pipe that directs most of the mess overboard. Fortunately diesels are pretty tolerant of back pressure and I can't tell any difference in operation or power.

As far as performance in flight I am quite pleased. Running is consistant, I have had no dead sticks, throttle response is prompt, the noise level is low compared to a similar size glow engine. It will turn a little larger propeller, and the fuel consumption is less.

Will I buy another diesel? Probably not. I will continue to fly the PAW and continue to learn, but there is no doubt that the advantages of the diesel come at the cost of increased complexity in operation. If you love to play around with machinery by all means give diesels a try, but If you just want to just crank up and fly, the glow engine is hard to beat.