Ron,
The speed change is only a couple knots from 1300-1450 pounds. Stall speed is
49 KIAS at 1370. Once you calibrate your airspeed system simply set the
horn/light
during in flight testing. See your POH.
Vstall is square root of Weight / (1/2 x rho x Cl x S) rho or density is
.00238,
Cl is about 1.6-1.7 and S is 100-110 square feet. Answer is in feet per second
so do the conversion.
5 knots is the accepted lead airspeed for the various warning systems in the
FARs
unless the plane is a computer driven squirrel that needs stick shakers and
trend indicators so they get exceptions.
I do the stall speed horn tests with flaps up and down to get the ideal speed
for
my client. Some builders insist on pitot tubes that are not installed to be
most accurate IAW manufacturers guidelines so calibration is necessary.
The Europa Pitot/static of course is placed properly and very accurate.
Instruments
and pitot/static connections must be checked always prior to first flight
in my opinion. What is on the gauge on the initial flight is a trend instrument
without testing and verification.
Stall strips reduce lift at the stall and the indicated airspeed of the stall
stripped
wing will be higher. The actual stall should be only a couple knots above
an unstripped wing and the buffet typically 5 knots higher than that. I
set the stall warning horn at the beginning of the burble if it is about 5 knots
above stall. Close enough. Fine tune to desired.
A super bright LED will not be welcome at night. A normal LED (1.5 to 2 volts)
and horn has worked well for years, especially a flashing light.
Don't over think it. I do not set the stall warning on my initial test flight.
I fly my airspeed because my instrument guy checked my indicator and
pitot/static
system. GPS ground speed is my backup initially.
If unable, put a suction on your altimeter to increase the altitude 1000 feet,
A/S should read 135 Knots and both should be steady for 30 seconds. VSIs are
designed to leak then should stabilize out so disconnect the VSI during this
ground test. If it fails this initial test, something is wrong, go fix it.
I've written before on this in more detail..
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of rparigoris
Sent: Tuesday, March 02, 2021 6:30 PM
Subject: Europa-List: Re: Stall warning airspeed for XS Mono
Thanks for replies. What is approx. indicated airspeed when flying light weight
and also near gross? I understand all aircraft will be a little different. I'm
in the middle of wiring and want to add a 2mm super bright red LED on our Winter
airspeed gauge close to where the needle would be about 5 knots above stall.
Thx. Ron P.
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