> Klaus wrote:
>
> >During those test flights I have found out that my RPM indicator reads 300
> >rpm too low!
> >Any ideas how I could calibrate it?
I have just downloaded a weeks worth of emails today and noticed this
one.
Cyclone Hovercraft Ltd, the UK distributor of Rotax engines do a very
nice handheld prop speed meter. This is an optical device so no hard
wiring or connections are required. Cost is about 50 (I think).
I purchased one about 8 years ago to callibrate the Rotax rev counter on
my Shadow microlight and it is very easy to use. Note that you need to
calculate the engine speed taking into account the gearbox drive ratio
reduction since you are only measuring the prop shaft speed. Also, most
rev counters that I have callibrated in the past were not linear so if
you get the readings correct at say 5000 RPM they are likely to be out
at 2000 RPM. The meter itself can be ajusted and callibrated using the
"standard" 50hz flicker of a mains light bulb (assuming the electricity
company generators run at this speed).
I would consider loaning my meter if anyone has a need to callibrate.
Carl Pattinson.
|