"Dan, U.S. Air Force, retired" wrote in message
...
.Blueskies. wrote:
"Montblack" wrote in message
...

First time I've stumbled across one of these:

Lift Reserve Indicator

http://home.hiwaay.net/~sbuc/journal/liftreserve.htm
"One of the AOA systems that has been around the longest is the Lift
Reserve Indicator. This unit was developed in the 1970's and has been
offered in a couple of different variations since then. There is
considerable controversy over just what the LRI actually measures and how
it operates, but when the price of the analog unit was recently reduced
substantially, it got my attention. Since the panel of 399SB is rather
unconventional, I had included a small backup airspeed indicator.
However, the AI was never used since I rely on the RMI uEncoder for pitot
info, so I decided to replace the AI with the LRI since it could also
serve as a backup airspeed indicator. The decision was easier since the
LRI would fit in the same space as the little AI and was in the pilot's
angle of vision."

http://www.liftreserve.com/
Company website - InAir Instruments


Montblack


Interesting, delta P between two sources, one more or less pointing
forward and one more or less pointing downward. I suppose the indicator
has a pressure diaphragm inside it linked to the needle...

I want an AOA indicator for the BD4 someday...

Hmmmmmm.......



A couple of years ago Kitplanes had an article about and AOA sytem that
used 2 ports flush with the wing surface near the wing tips. It's a
simplified version of a system the military has been using for decades.
The military version uses a conical probe sticking out of the side of the
fuselage. There are two sets of slots a few degrees part facing towards
the front of the airplane. These slots are ports that send air pressure to
two sensing chambers. Here's where they decided to get complicated: the
cone is then driven until the chamber measure equal pressure. The cone's
position is then transmitted to an indicator. Obviously the system isn't
for single engine tractor airplane. The 3.125" indicator is a tad big for
most homebuilts, but does contain switches for stall warning and AOA
indexer lights. It seems to me some enterprising electronics genius should
be able to design a simple system that does all this in solid state.

Dan, U.S. Air Force, retired

I'd also like an electronic AOA indicator. There are several probes that
work on three pressure pickups like
(http://www.cgmasi.com/aviation/index.html). In sailplanes we can just
tape a couple of yarns of the side of the canopy and mark the inside with
grease pencil.

bildan