Nigel Charles wrote:
> ...
> An rpm gauge is the only engine gauge which I feel needs analogue display.
> Ironically these are often the ones which need the most setting up. Mine
> overeads by 200rpm at 5800rpm.
RPM should be the most suspect of all. Convenient to think digital is
more accurate, but you can't just count pulses - accurate to within
parts per million, but at even 50RPM resolution, the display update
rate is unacceptable. Other approaches then become dependent on
mechanical and other issues in the stator ass'y from whence come the
pulses, with accuracy attainable with $$, unless the higher price is
just more profit. Same for analog gauges. Digital RPM checkers which
read optically are very accurate and affordable. Borrowing or buying
one of these is arguably a must! Or a freq counter from Radio Shack
and do the math.
My 2-1/4" UMA backup airspeed read shockingly high at stall speeds;
the exchange is only tolerable. I bought a $28 digital bath scale
---From Wal-Mart for W&B. An FAA-certificated shop which calibrates
aircraft mechanics' instruments found it with .5# all up/down. Like
their digital meat thermometer. When you can go to Wal-Mart and get
better quality than what's passed off as aircraft components (for
experimentals), it's all very sad.
Best,
Fred F.
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