X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 18 Jan 2010 08:43:13 -0500 Message-ID: X-Original-Return-Path: Received: from imr-db03.mx.aol.com ([205.188.91.97] verified) by logan.com (CommuniGate Pro SMTP 5.3.1) with ESMTP id 4084872 for lml@lancaironline.net; Sat, 16 Jan 2010 08:59:52 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.91.97; envelope-from=Sky2high@aol.com Received: from imo-ma04.mx.aol.com (imo-ma04.mx.aol.com [64.12.78.139]) by imr-db03.mx.aol.com (8.14.1/8.14.1) with ESMTP id o0GDx5wJ017522 for ; Sat, 16 Jan 2010 08:59:05 -0500 Received: from Sky2high@aol.com by imo-ma04.mx.aol.com (mail_out_v42.5.) id q.c7a.6be000b8 (37067) for ; Sat, 16 Jan 2010 08:59:00 -0500 (EST) Received: from smtprly-de01.mx.aol.com (smtprly-de01.mx.aol.com [205.188.249.168]) by cia-db05.mx.aol.com (v127.7) with ESMTP id MAILCIADB051-b22d4b51c61e1e8; Sat, 16 Jan 2010 08:59:00 -0500 Received: from magic-d01.mail.aol.com (magic-d01.mail.aol.com [172.19.161.129]) by smtprly-de01.mx.aol.com (v127.7) with ESMTP id MAILSMTPRLYDE012-b22d4b51c61e1e8; Sat, 16 Jan 2010 08:58:54 -0500 From: sky2high@aol.com X-Original-Message-ID: <2c27.1236d10f.3883201e@aol.com> X-Original-Date: Sat, 16 Jan 2010 08:58:54 EST Subject: Re: [LML] Airspeed sensing switch needed X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_2c27.1236d10f.3883201e_boundary" X-Mailer: AOL 9.5 sub 155 X-AOL-ORIG-IP: 67.175.242.202 X-AOL-IP: 172.19.161.129 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_2c27.1236d10f.3883201e_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Bill, Here is one: _http://www.aerocraftparts.com/ItemForm.aspx?item=710_ (http://www.aerocraftparts.com/ItemForm.aspx?item=710) I believe it has NC and NO contacts so it could be used as both an air driven squat switch and as a gear warning device at certain fixed speeds. Others have used an adjustable washing machine water level switch although I'm not sure how it would be plumbed. Mcmaster-Carr also has some inexpensive pressure differential switches (pitot/static): _http://www.mcmaster.com/#differential-pressure-switches/=5edv31_ (http://www.mcmaster.com/#differential-pressure-switches/=5edv31) Remember that low airspeed = low pressure differential. Pressure in Units IAS mph Knots "H2O "Hg PSI 40 34.8 0.79 0.06 0.028 50 43.4 1.23 0.09 0.044 60 52.1 1.77 0.13 0.064 70 60.8 2.41 0.18 0.087 80 69.5 3.15 0.23 0.114 90 78.2 4.00 0.29 0.144 100 86.9 4.94 0.36 0.178 I am sure there are circuit board suitable differential pressure sensors used in AOA systems and in certain air/data computers. Here is one: _http://www.mouser.com/ProductDetail/Honeywell/ASDX001D44R-DO/?qs=pLJKYPamQJ y1Yap2j%2fDUNQ%3d%3d_ (http://www.mouser.com/ProductDetail/Honeywell/ASDX001D44R-DO/?qs=pLJKYPamQJy1Yap2j/DUNQ==) The now discontinued Rocky Mountain Instrument's micro-encoder has a speed that could be set for annunciating a gear warning. Advanced Systems AOA also has a gear warning mode. Good Luck Scott Krueger In a message dated 1/16/2010 7:29:17 A.M. Central Standard Time, bill_kennedy_3@hotmail.com writes: I'm going to build the gear not down warning system suggested by Randy Stuart in an earlier email. I thought Aircraft Spruce had a airspeed sensing switch, but I couldn't find it in their catalog. Can any of you help me find a source for the pressure switch? I've never had a close call with the gear in three plus thousand hours of retractable time, but I've always been a little uneasy with no warning system in my LNC2. I had hoped that I could talk Blue Mountain Avionics into building a warning system into their EFIS, but that didn't work out. Randy's system looks great to me and I'm eager to try it. I've attached Randy's drawing just in case others might want to revisit the idea. Thanks -- Bill Kennedy = -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html --part1_2c27.1236d10f.3883201e_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Bill,
 
Here is one:
 
 
I believe it has NC and NO contacts so it could be used as both an ai= r=20 driven squat switch and as a gear warning device at certain  fixed=20 speeds. 
 
Others have used an adjustable washing machine water level switch alt= hough=20 I'm not sure how it would be plumbed.
 
Mcmaster-Carr also has some inexpensive pressure differential sw= itches=20 (pitot/static):
 
 
Remember that low airspeed =3D low pressure differential.
 
=
Pressure in Units
IAS mph= Knots =  "H2O "Hg PSI
40 34.8 0.79 0.06 0.028
50 43.4 1.23 0.09 0.044
60 52.1 1.77 0.13 0.064
70 60.8 2.41 0.18 0.087
80 69.5 3.15 0.23 0.114
90 78.2 4.00 0.29 0.144
100 86.9 4.94 0.36 0.178
 
I am sure there are circuit board suitable differential pressure sens= ors=20 used in AOA systems and in certain air/data computers.
 
Here is one:
 
http://www.mouser.com/ProductDet= ail/Honeywell/ASDX001D44R-DO/?qs=3DpLJKYPamQJy1Yap2j%2fDUNQ%3d%3d
 
 
The now discontinued Rocky Mountain Instrument's micro-encoder has a= =20 speed that could be set for annunciating a gear warning. = =20 Advanced Systems AOA also has a gear warning mode. 
 
Good Luck
 
Scott Krueger 
 
In a message dated 1/16/2010 7:29:17 A.M. Central Standard Time,=20 bill_kennedy_3@hotmail.com writes:
I'm=20 going to build the gear not down warning system suggested by Randy Stuar= t in=20 an earlier email. I thought Aircraft Spruce had a airspeed sensing switc= h, but=20 I couldn't find it in their catalog. Can any of you help me find a sourc= e for=20 the pressure switch?

I've never had a close call with the gear in= three=20 plus thousand hours of retractable time, but I've always been a little= uneasy=20 with no warning system in my LNC2. I had hoped that I could talk Blue Mo= untain=20 Avionics into building a warning system into their EFIS, but that didn't= work=20 out. Randy's system looks great to me and I'm eager to try it. I've atta= ched=20 Randy's drawing just in case others might want to revisit the=20 idea.

Thanks -- Bill Kennedy
=3D

--
For archives and= unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html
--part1_2c27.1236d10f.3883201e_boundary--