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My RMI encoder has the ability to display speed in Mach number as well.
However, I believe that when top speed is a function of Mach number it is
not a flutter issue, but an issue of localized trans-sonic airflow on the
airframe - usually around the engine intake. I doubt that the Lancairs are
experiencing issues with near sonic air flow except possibly at the
propeller tips.
That being said, mach number is going to more accurately represent a given
TAS than would the IAS (mach number would be even more conservative as it
will increase slightly as you go higher while IAS decreases significantly -
given you are flying at a fixed TAS). I am sure the Chelton has the ability
to display TAS as well, so I wonder why they use mach number instead of TAS.
It could be for the propeller tips but more likely just to sound cool.
Maybe I will start flying around with mach number on display and see how it
goes. ;-)
Dave Leonard
"Ed Anderson" <eanderson@carolina.rr.com> wrote:
"""
The bottom line is that at the higher altitudes your indicated airspeed
gauge
can be showing you safely below the Red Vne mark but, your True
Airspeed may
be exceeding Vne by a considerably margin putting your airframe in a
potentially danger zone of flutter.
"""
The Lancair IVPs, being designed for turbocharged flight, spend
most of their
cruise time in the flight levels. Vne for that aircraft is mach
.52... the
Cheltons (and other glass cockpits, I imagine) have the ability
to monitor
that speed directly, and Vne is adjusted and displayed based on
altitude, OAT,
etc (ie, TAS). The Vne parameter is entered as a mach number in
the Chelton's
setup mode. Pretty amazing stuff.
<Marv>
>> Homepage: http://www.flyrotary.com/
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
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