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Model Forum / Radio Controlled / Helicopters / November 2003Smokey heli engines
Hi Is it just me or do you heli guys run your engines extra rich? or add extra oil? They seem to smoke a lot more than any fixed wing plane ive ever seen, im just curious and know nothing (at the moment) about helicopters. BoB > Hi > Is it just me or do you heli guys [quoted text clipped - 4 lines] > > BoB Hi Bob, Needs to be done because our engines don't get as much airflow as a plank engine does, so instead of air, we use the oil in the fuel to take the heat away. HTH Andy >Hi >Is it just me or do you heli guys [quoted text clipped - 4 lines] > >BoB Hi BoB, Nope, it's not just you. You'll find that different brands of fuels run different kinds of oil in the premix and they also run different percentages of oil in the premix so there can be a fairly wide difference in how much smoke is produced. Having said that, we do tend to run our model helicopter engines richer on the fuel mixture than our fixed wing brothers do. One reason for that is, as good as our cooling systems are, they're not as good as having the cylinder sitting out in the prop blast while flying around at 70 to 100 mph. The added fuel running through the engine helps to cool things down. FWIW, Fly Safe, Steve R. "Rhodesst" <rhodesst@aol.com> wrote BoB wrote: > >Is it just me or do you heli guys > >run your engines extra rich? or add extra oil? [quoted text clipped - 12 lines] > out in the prop blast while flying around at 70 to 100 mph. The added fuel > running through the engine helps to cool things down. Heli's tend to be running at fairly high throttle whilst only in the hover too, so there's more smoke whilst the model is stationary than with fixed wing models. That prop' blast Steve R. mentioned above does a pretty good job of dispersing the condensed oil vapour 'smoke' too - if you look at a heli in fast forward flight then the smoke trail isn't anymuch more evident than with a fixed wind model at similar throttle settings. Ciao... [UK]_Nick...  SignatureNick M V Salmon Master Mariner MN(Retd.) Mailto: My four initials@btinternet.com http://www.nmvs.btinternet.co.uk/index.htm Very good question... one I've wondered about for some time. I run my engines pretty close to full lean and I only mix 14% oil and they smoke a ton. I've decided that there are a few things that contribute. We run really big mufflers and that helps to cool the exhaust some and maybe the oil condenses out more than in an airplane. The other is (and someone else already mentioned) a .90 with no airflow to disperse the smoke is going to look smokier. It's my contention that if you took an "airplane" engine, put it on a test stand, ran it with a load but no air flow to move the exhaust around... it smoke just as much. So... no I don't run my engine extra rich, and no I don't add extra oil, and yes mine smoke a ton. It's gota be the muffler/airflow. I think :-) Bill Vail > Hi > Is it just me or do you heli guys [quoted text clipped - 4 lines] > > BoB > Very good question... one I've wondered about for some time. I run my > engines pretty close to full lean and I only mix 14% oil and they smoke a [quoted text clipped - 8 lines] > So... no I don't run my engine extra rich, and no I don't add extra oil, and > yes mine smoke a ton. It's gota be the muffler/airflow. I think :-) OK, thanks for all the replies, it seems that they smoke more due to lack of air flow over the engine and exhaust, what about nitro cars? ive owned a few in my time and none have smoked that bad. The down draught of a helis rotors must be greater than head wind of a car? The only fuel I have ever used for cars and planes has been Dyno glo 5, I take it the 5 is the nitro content? as you can tell I know very little about these engines. But I do know how a 2 stroke engine works. BoB try wildcat fule it smokes a hel of a more than coolpower or pro-synth > > Very good question... one I've wondered about for some time. I run my > > engines pretty close to full lean and I only mix 14% oil and they smoke a [quoted text clipped - 23 lines] > > BoB so we can write 3d things in the air. > Hi > Is it just me or do you heli guys [quoted text clipped - 4 lines] > > BoB lol > so we can write 3d things in the air. > [quoted text clipped - 6 lines] >> >>BoB |
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