Air Pressure Switch for Hour Meter

Hello all, can somebody suggest a good place to get an air pressure
switch to hook into the Pieto line of an aircraft which will then in
turn operate the hourmeter when the aircraft is flying.

I have a friend who has a really long taxi and warmup time and he tells
me he is putting too many hours on these aircraft which are not from
actually flying. He wants to install a switch which will give him more
accurate times.

I have had a quick search of the Internet but unfortunately cannot find
exactly what we need (i think). Any help appreciated, regards Michael

See if you can figure out a placement on the landing gear for a simple
microswitch with a spring leaf for overtravel.---Hatz??

or make your own pressure switch , a diaphragm of thin glove leather , a
thin alum plate glued on one side to actuate a small
microswitch--microswitch will probably supply enough spring pressure to
return the diaphragm. They haven't found anything any better for wind
organ actuating mechanisms in a thousand years or so.--- WW-II airspeed
instruments used leather diaphragms in their airspeed indicators.You
should have a water trap in the pitot line anyhow.--wassbiplane


NEW-USER wrote:
Hello all, can somebody suggest a good place to get an air pressure
switch to hook into the Pieto line of an aircraft which will then in
turn operate the hourmeter when the aircraft is flying.

I have a friend who has a really long taxi and warmup time and he tells
me he is putting too many hours on these aircraft which are not from
actually flying. He wants to install a switch which will give him more
accurate times.

I have had a quick search of the Internet but unfortunately cannot find
exactly what we need (i think). Any help appreciated, regards Michael

NEW-USER wrote:

Hello all, can somebody suggest a good place to get an air pressure
switch to hook into the Pieto line of an aircraft which will then in
turn operate the hourmeter when the aircraft is flying.

I used a switch in the pitot line for exactly this purpose. Go to
"www.digikey.com" and search for "pressure switch". Determine what
speed you want the switch to come on at (I chose 40 mph) and then
determine what pressure will be created at that speed and choose the
appropriate switch. I don't remember which one I used.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2007

Good idea! As I don't know how to calculated this, to get me in the
ballpark do you know/remember the pressure at 40 mph?

Ron



"Marc J. Zeitlin" wrote in message
...
NEW-USER wrote:

Hello all, can somebody suggest a good place to get an air pressure
switch to hook into the Pieto line of an aircraft which will then in turn
operate the hourmeter when the aircraft is flying.

I used a switch in the pitot line for exactly this purpose. Go to
"www.digikey.com" and search for "pressure switch". Determine what speed
you want the switch to come on at (I chose 40 mph) and then determine what
pressure will be created at that speed and choose the appropriate switch.
I don't remember which one I used.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2007


--
Posted via a free Usenet account from http://www.teranews.com

I saved this from a post here some years ago:

begin save

Document AN 05-10-24 specifies the airspeed that should be indicated
by a given water column. There is an approximation formula that says that

Airspeed (Statute MPH) = sqrt (Water Pressure In Inches * 1980.0)

If you do the formula right, 100 MPH should come out about 5 inches of
water column.

end save

I use 30 feet of water for one atmosphere (approximately 15 psi). None of this
is exact but then again nothing is.

CW

"Ron" wrote:

Good idea! As I don't know how to calculated this, to get me in the
ballpark do you know/remember the pressure at 40 mph?

Ron



"Marc J. Zeitlin" wrote in message
...
NEW-USER wrote:

Hello all, can somebody suggest a good place to get an air pressure
switch to hook into the Pieto line of an aircraft which will then in turn
operate the hourmeter when the aircraft is flying.

I used a switch in the pitot line for exactly this purpose. Go to
"www.digikey.com" and search for "pressure switch". Determine what speed
you want the switch to come on at (I chose 40 mph) and then determine what
pressure will be created at that speed and choose the appropriate switch.
I don't remember which one I used.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2007