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RE: REFLECTOR: airspeed indicator markings
We at the factory have established the following airspeed limits on all our
airplanes. White arc (actually speed brake speed) of 65 to 110 knots.
Green arc of from 65 to 170 knots. ( the 170 knots would be the maximum
structural cruise speed) and the yellow arc from 170 knots to 200 knots.(
200 knots being the Vmc) All speeds are indicated assuming proper
calibration has been done. Although no markings are normally used for
maneuvering speed, this is 140 knots. (this is the speed where instant and
full deflection of the controls can be made safely) Many of our airspeed
indicators have the green arc stopping at 140 knots, however, this should
actually be 170) It is important in an experimental airplane that the Vmc
and all flutter testing be done by the builder. Many kit manufacturers
refuse to publish any airspeed limitations due to liability. We, as kit
manufacturers, can never be sure YOUR airplane was built properly. We
generally test our airplanes up to about 220 knots indicated as a 10%
Sincerely, Duane Swing
From: Bob Ginsberg [SMTP:email@example.com]
Sent: Sunday, July 11, 1999 6:49 PM
To: Velocity Reflector
Subject: REFLECTOR: airspeed indicator markings
The question of the markings on the airspeed indicator is a good one.
Other than the speed brake limit of 110 knots on my fixed gear 173, I
know of no factory designated maximum speed, normal operating speed,
minimum speed, or maneuvering speed. Now, some of these should probably
be determined by the builder during flight trials. But as far as I
know, maneuvering speed (which isn't typically marked, and varies with
weight anyway), can only be calculated.
I put the white arc at 60 to 110 knots, representing the minimum speed
at which I ever stalled the canard, to the speed brake limit. I put the
green arc up to 163 knots, simply because that was what Dan Maher said
was his best speed on the 173 fixed, I put red at 200 knots because,
... I don't really know because. I figured the FAA would want some type
of markings on the plane's airspeed indicator.
I would love to hear what other people have done here.
Bob Ginsberg, M.A., CSCS, CPT
Big Ape Gyms - Velocity 173