Mailing List lml@lancaironline.net Message #27714
From: Dan Schaefer <dfs155@adelphia.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: Approach control
Date: Tue, 18 Jan 2005 18:56:19 -0500
To: <lml@lancaironline.net>
Dom Crain wrote:

<<<Given (I assume) all our ASI's are calibrated in KNOTS, why do people
  insist on using MPH when describing anything related to aircraft speed?>>>

Not necessarily true. Back when I bought the ASI for my early 235 (with the
Lancair logo and appropriate color markings) you took what was available -
meaning one that had MPH in the outer scale and Knots on the smaller inner
scale (which has far lower resolution).

However, I fail to see the significance of whether it points out MPH, Kts or
Furlongs per Fortnight - once you've fully characterized your airplane,
these are nothing but reference numbers. If you consistently fly an approach
at 72 Kts, 83 MPH, Warp .000002 or when the big hand is at two o'clock, it's
pretty much all the same. It's just all in what you get used to, I guess.

Since I have a GPS in the panel that gives GS in knots, I use that for
navigation checks but have no problem using my MPH reading ASI for any other
needed reference.

Besides, unless our LNC2's all have the identical instrument and pitot
installation error, and therefore identical CAS vs IAS indications (which I
firmly doubt), passing these numbers around is probably less than
meaningful.

Dan Schaefer
LNC2 #52   N235SP


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