> Heli people
> Here's the scenario:
> Shuttle Z-TS
> Irvine 36 F1 engine (a few weeks old - had about a gallon through it).
> Hatori 333 pipe
> Main needle 1.5 to 1.75 turns open
> Model Technics Contest 10 (10% nitro) (and also Contest 10 with 15% nitro)
> Enya No. 3 plug
> Runs fine in all circumstances (fff, power ascents, hover), BUT...
> rapid descents with -5 to -7 degrees pitch and idle up ON (about 40-50%
> throttle) the engine misfires (sound "crackly")
> Seens to be cured by running very rich, but fuel consumption is unacceptably
> high (also too much smoke!).
> (my guess - should I have more throttle??)
> I want to do loops but not if its going to misfire at the top!!!
> Any ideas anyone?
> Simon D.
> Colchester UK.
I have tried 10% Nitro in an Irvine F1 (but with a fully tuned
pipe) and i could not tune it properly so that it wouldn't tend to
overheat ,whilst also maintaining an even balanced clean running mixture
across the whole throttle range ,from a full to 1/4 full tank.At first i
thought it might be the Enya no.3 (which i also was using first) that
was too hot a plug ,but i tried colder plugs too but it didn't cure the
problem completely either.You will find it is fine when flying around
using 3/4 to full throttle with a rich main needle setting but tends to
overheat in the mid range after prolonged hovering and will "buzz" or
misfire when making descents or buzz high idle when hitting the throttle
hold unless both the top end (main needle) and the idle
(transition/tickover) needles are set quite rich.
Try a different heat rating of plug or drop the nitro content by using
Sport5 instead of Contest10.During the colder months you may be able to
move back to the Contest10 but during the last couple of weeks
you'll probably find it runs like shit on 10% unless setup very rich.The
F1 is a high compression engine and runs really too hot on nitro levels
above 5%.You could increase your throttle % 'tage to get more fuel
through at the troublesome throttle range but it will just increase your
overall fuel consumption.