Dseielized Cox question

Thanks Ian,

I am hoping that the air flow from flying will keep them cool enough. But, since it is nearly summer and our temps are usually in the mid to upper 90's I will definitely keep the modified fuel blend in mind. I am surprised at how many little differences there are between glow and diesel.

Thanks,

Bob

I've never had any heating problems with the PeeWee or the Queen Bee on Diesel. You do need to stay on the safe low compression side though. If the heat does start to build up the compression will be even more too high, and so on, in an escalating fashion (or unstable run-away, not sure what the proper wording would be here).

This is general general thing though, any diesel engine will behave like that. If you have throttled engine you need to be extra careful as at reduced throttle the engines tend to like a little higher compression setting and it is easy to get fooled into a too high setting, that will then over-heat at full throttle in the air. So during flying the engines should always hit and miss at reduce throttle settings, otherwise the compression ratio is too high for full throttle.

Bernie's "Throttle" is merely a cold start choke, so all the settings needs to be done att wide open throttle, and then you will just have to live with what ever throttling it can produce for that setting. Don't try to tune it at reduced settings, that will only trick you into something that doesn't work at full throttle...

Well, I guess 70-80F is usual here too on a good day in the summer. I didn't run any engines in australia when I was there two years ago, but their winter felt like a pretty good summer to me.

To me it has less to do with ambient temperature, and more about the actual settings. You do need to avoid the escalating run-away situation. The fake throttle just adds to the problem, when trying to get a good idle you will tune away from the proper settings for full throttle, that is the real danger.

A diesel engine has something that one could call "positive feedback" of the temperature, i.e. when the temperature goes up, then the effective compression setting goes up to, thus producing more heat and so on. This will not stop until something breaks in the worst case. You can get this with any diesel engine in any ambient condition, e.g. if you tune a cold engine and take off flying straight away, in winter or summer.