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View Full Version : CEM..fuel mixture and supercharger advice needed



salthill
03-29-2005, 03:18 AM
hi,
can someone give give me the lowdown on using these features. i've noticed that on the yak9 above 3100m it smokes unless you reduce? mixture.
what planes need intesive use of these features and are rewarded by better faster acceleration and speed
also whats the best way to reduce speed on planes like the p51 where reducing the trottle? has no immediate effect

thanks in advance

salthill
03-29-2005, 03:18 AM
hi,
can someone give give me the lowdown on using these features. i've noticed that on the yak9 above 3100m it smokes unless you reduce? mixture.
what planes need intesive use of these features and are rewarded by better faster acceleration and speed
also whats the best way to reduce speed on planes like the p51 where reducing the trottle? has no immediate effect

thanks in advance

salthill
03-30-2005, 03:21 AM
bump
-come on you GURU's
cheers

jurinko
03-30-2005, 03:36 AM
supercharger: depends on plane. P-39 has one-speed one so no need to switch, Yak has two stages (switch in 2500m) and US Navy birds have even three stages (switch to 2500 and 6500m). It is needed to keep the engine power in thinner air up high by forcing more air into the engine. 109/190 has auto switch (you may see the MP rise around 3200m in 190 easily) and P-47 has a turbo which runs depending on the need and altitude.
The altitudes for switching the blowers for each plane are in the pdf manual.

Mix - for planes with manual mix adjustment you have to lean the mixture as you get up high, as with the thinner air, the air:fuel ratio coming to the combustion chambers changes and must be set to optimal value again. 190/109 and many others have no manual but auto mix control. US Navy birds have just 100%/auto - 120%, when 120% can be used only down low for take-off or escape. If your mix is too rich, the fuel does not burn completely and you may see the smoke and power loss. To save fuel on longer flights, you may go down with the mix but also the power generated by the engine is lower.