Today's Message Index:
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1. 12:50 AM - DIY manometer to check your ASI (Aero Siam)
2. 01:18 AM - Stall warning system question (Aero Siam)
Message 1
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| Subject: | DIY manometer to check your ASI |
The link below gives instruction to build a manometer. This article appeared in
EAA Sport Aviation in August 2006.
http://www.iflyez.com/manometer.shtml
The manometer allows you to check your CAS and correct the IAS readings. That only
leaves position error.
The author suggests blowing into the inlet tube. I suggest a 20cc syringe which
is much more controllable. You can use 2 hands (butting against each other) to
ensure the plunger can not slip and over-pressure the system.
The factory-installed ASI was quite inaccurate - underreading at low and overreading
at high speeds. I recalibrated it to make it both read accurately and to
read in knots instead of mph.
>From memory, there are 3 plates with screws inside the ASI. The high speed plate
is easy to set but any alteration to the low speed plate affects the speeds
up the scale as the plates impinge on each other.
I bought a second ASI for redundancy. It overread at approach speeds by 5 knots
which was unsafe and needed to be recalibrated. I later added a Dynon. To minimise
position error, I set the Dynon pitot at minus 5 degrees to give accurate
readings at high angles of attack. This is helped by the conical design of the
pitot tube.
At half flap with the stall warning on and level flight, the Dynon reads 38 kts
and the ASI 30.
At full flap, Dynon is 32 and ASI 20. At speeds above 45, all 3 read accurately.
This plane is fitted with vortex generators which lowered the stall speed and
also improved the slow speed handling.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499947#499947
Attachments:
http://forums.matronics.com//files/dynon_and_asi_2_751.png
Message 2
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| Subject: | Stall warning system question |
My plane was laid up for a while and the hoses to the stall warning pressure switch
disintegrated in the high humidity. Does the hole in the leading edge connected
to the pressure switch operate on suction or pressure?
The pressure switch is permanently live, presumably to allow testing on the pre-flight.
If so, are owners sucking or blowing to test it?
Regards
Paul
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499948#499948
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