---------------------------------------------------------- Allegro-List Digest Archive --- Total Messages Posted Sun 01/03/21: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:50 AM - DIY manometer to check your ASI (Aero Siam) 2. 01:18 AM - Stall warning system question (Aero Siam) ________________________________ Message 1 _____________________________________ Time: 12:50:28 AM PST US Subject: Allegro-List: DIY manometer to check your ASI From: "Aero Siam" 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 _____________________________________ Time: 01:18:24 AM PST US Subject: Allegro-List: Stall warning system question From: "Aero Siam" 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 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message allegro-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Allegro-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/allegro-list Browse Digests http://www.matronics.com/digest/allegro-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.