?? Lift Reserve Indicator ??

[Montblack]

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

[.Blueskies.]

"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.......

[Dan, U.S. Air Force, retired]

..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

[Bill Daniels]

"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

[.Blueskies.]

"Bill Daniels" <bildan@comcast-dot-net> wrote in message ...
>
> "Dan, U.S. Air Force, retired" > wrote in message ...

>>
>> 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
>

Here is an electronic version: http://advanced-control-systems.com/AOA/aoa.htm

Two pickups; one on the top of the wing and one on the bottom...

[Smitty Two]

In article >,
"Montblack" > wrote:

> 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

Hey, most of you old guys are even older than I am. Didn't they used to
hang AOA indicators on the wing struts of biplanes? A little flat plate
that moved a big needle around a graduated arc as it was pushed by the
relative wind? Sort of like a weathervane. Or was that just an airspeed
indicator I'm thinking of?

[Richard Lamb]

Icebound wrote:
> ".Blueskies." > wrote in message
> t...
>
>>
>>Interesting, delta P between two sources, one more or less pointing
>>forward and one more or less pointing downward.
>
>
>
> Basically a stall horn, with the lowered pressure activating a meter instead
> of a sound-producing reed. As the pressure falls at the horn, the needle
> swings deeper toward the red.
>

Are we sure that the sensor is a pressure type sensor?

The A-4 Skyhawk uses a paddle type vane on the side of the aircraft's nose.
I'm assuming a simple potentiometer is attached to the vane to read position.
Very straight forward mechanical approach.

Another approach would be to use a pair of thremosistors carefully positioned
inside the slots of the external sensor.

Differences in the air flow inside the two slots (as mentioned previously)
would cause temperature variations of the thremosistors according to AoA.

The electrical difference between the two thremosistors is properly scaled and
can be used to monitor AoA.

I don't have my "library" handy. All that is still packed up in storage.
So I can't pull the relevant details up this morning.
But the Sport Aviation index came up with the references listed below.

Food for thought....

Richard


References:

May '78
Preliminary Report-Development of a Poor Man's VFR Autopilot/Don Hewes

March '79
Update On The Poorman's Autopilot... by Donald E. Hewes

February '80
Autopilot System For Homebuilt Airplanes... by Don Hewes

August '80
Fine Tuning The Electro-Fluidic Autopilot.. . by Doug Garner

April '81
Muscle For Your Homebuilt Autopilot... by Don Hewes

November '81
A Magnetic Heading Reference For The Electro Fluidic Autopilot,Part I
by Doug Garner

December '81
Magnetic Heading Performance For The Electro Fluidic Autopilot
Part 11 . . , by Doug Garner

[Stew Hicks]

I downloaded a homebuilt version of a AOA some time ago. If you want it
contact me and I will I will attach a copy and send it to you.





"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

[wright1902glider]

The last vane-type indicator I witnessed was hanging on the strut of a
New Standard DB-25 (circa 1926). It was an airspeed indicator and
appeared to function quite well from my perspective in the forward-left
front seat.

Orville Wright used a vane-type device in the autopilot system he
invented. While this was the world's first functional autopilot, it
never became popular. Sperry's gyroscopic autopilot system hit the
market shortly after, and was superior.

I'm not familiar with any vane-type AOA indicators that could be
mounted on a strut, but that doesn't mean that they didn't exist. If
anyone knows of one, I'd like to see it.

Harry

[[email protected]]

On 14 Feb 2006 08:29:37 -0800, "wright1902glider"
> wrote:

>I'm not familiar with any vane-type AOA indicators that could be
>mounted on a strut, but that doesn't mean that they didn't exist. If
>anyone knows of one, I'd like to see it.

I saw a very simple one in Kitplanes years ago. It was a vane
attached to a backing plate that was painted white, and had degrees on
it, and a big red area that represented the critical angle of attack,
beyond which the airplane stalled.

It was mounted to the wing strut in a vertical position so that you
could see it by turning your head left. Or right, it doesn't matter
on which side you mount it.

There were other versions of this that connected the vane to a
transducer which then transmitted the angle of the vane to a display
on the instrument panel.

I've always thought this (AOA indicator) was a good idea.

Corky Scott

[Peter Dohm]

"Bill Daniels" <bildan@comcast-dot-net> wrote in message
...
>
> "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
>
>

Light :-)
Simple :-)
Reliable :-)
But, won't work for single engine tractor airplanes :-(

[Peter Dohm]

"wright1902glider" > wrote in message
oups.com...
> The last vane-type indicator I witnessed was hanging on the strut of a
> New Standard DB-25 (circa 1926). It was an airspeed indicator and
> appeared to function quite well from my perspective in the forward-left
> front seat.
>
> Orville Wright used a vane-type device in the autopilot system he
> invented. While this was the world's first functional autopilot, it
> never became popular. Sperry's gyroscopic autopilot system hit the
> market shortly after, and was superior.
>
> I'm not familiar with any vane-type AOA indicators that could be
> mounted on a strut, but that doesn't mean that they didn't exist. If
> anyone knows of one, I'd like to see it.
>
> Harry
>
I don't recall whether I saw the one on the New Standard personally, or in a
picture, as it was still flying at Sun-n-Fun a couple of years ago. It may
well have been a picture as I didn't go up. IIRC, it looked, more than
anything else, an AoA calibrated as airspeed at some typical
loading--probably gross.

[Dan, U.S. Air Force, retired]

..Blueskies. wrote:
> "Bill Daniels" <bildan@comcast-dot-net> wrote in message ...
>
>>"Dan, U.S. Air Force, retired" > wrote in message ...
>
>
>>> 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
>>
>
>
> Here is an electronic version: http://advanced-control-systems.com/AOA/aoa.htm
>
> Two pickups; one on the top of the wing and one on the bottom...
>
>
That's the system I waas thinking of.


Dan, U.S. Air Force, retired

[Dan, U.S. Air Force, retired]

Richard Lamb wrote:
> Icebound wrote:
>
>> ".Blueskies." > wrote in message
>> t...
>>
>>>
>>> Interesting, delta P between two sources, one more or less pointing
>>> forward and one more or less pointing downward.
>>
>>
>>
>>
>> Basically a stall horn, with the lowered pressure activating a meter
>> instead of a sound-producing reed. As the pressure falls at the horn,
>> the needle swings deeper toward the red.
>>
>
> Are we sure that the sensor is a pressure type sensor?
>
> The A-4 Skyhawk uses a paddle type vane on the side of the aircraft's nose.
> I'm assuming a simple potentiometer is attached to the vane to read
> position.
> Very straight forward mechanical approach.

There were/are 2 variations of the system you describe. The one on the
A-4, T-39 etc do have resistance strips and switches inside the can on
the otherside of the skin from the vane. The one I have only has
switches. I don't know what it came off of. I am going to modify it to
synchro or resistance depending on how energetic I feel.

Dan, U.S. Air Force, retired

[ET]

"Dan, U.S. Air Force, retired" > wrote in
news:w3xIf.1376$et.1235@dukeread12:

> .Blueskies. wrote:
>> "Bill Daniels" <bildan@comcast-dot-net> wrote in message
>> ...
>>
>>>"Dan, U.S. Air Force, retired" > wrote in message
...
>>
>>
>>>> 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
>>>
>>
>>
>> Here is an electronic version:
>> http://advanced-control-systems.com/AOA/aoa.htm
>>
>> Two pickups; one on the top of the wing and one on the bottom...
>>
>>
> That's the system I waas thinking of.
>
>
> Dan, U.S. Air Force, retired

I plan on putting this one in my Sonex:

http://www.ch601.org/resources/aoa/aoa.htm

--
-- ET >:-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

[wright1902glider]

Hmmm....

http://www.waldowrights.com/pictures.asp

Check out the 8th photo down, left hand column. Watever that thingy
is... I remember it being an airspeed indicator, but I could be wrong.
Its been a while.

I shared a hangar with these guys at Celebrate Freedon 2004 in Camden,
SC. Rob is a really nice guy and is only about 6'7". Dunno how he fits
in that plane. His tent was off to the left of Kermett Weeks' P51-C. I
was to the right and behind. The Berlin airlift Museum's C-54 was just
to the right of me. I went up with him and 3 other fellows at dusk on
Sunday night after the show. Extremely cool.

Any guesses on who invented the vane-type AOA? I'm gonna have to look
that one up. I know that Orville was working with similar devices from
about 1909 through the 1920's. Early Wright machines were extremely
pitch sensitive. Most had an AOA window of -2 to +10 degrees. Any more
or less could, and frequently did, mean death.

Harry

[Peter Dohm]

"wright1902glider" > wrote in message
oups.com...
> Hmmm....
>
> http://www.waldowrights.com/pictures.asp
>
> Check out the 8th photo down, left hand column. Watever that thingy
> is... I remember it being an airspeed indicator, but I could be wrong.
> Its been a while.
>
> I shared a hangar with these guys at Celebrate Freedon 2004 in Camden,
> SC. Rob is a really nice guy and is only about 6'7". Dunno how he fits
> in that plane. His tent was off to the left of Kermett Weeks' P51-C. I
> was to the right and behind. The Berlin airlift Museum's C-54 was just
> to the right of me. I went up with him and 3 other fellows at dusk on
> Sunday night after the show. Extremely cool.
>
> Any guesses on who invented the vane-type AOA? I'm gonna have to look
> that one up. I know that Orville was working with similar devices from
> about 1909 through the 1920's. Early Wright machines were extremely
> pitch sensitive. Most had an AOA window of -2 to +10 degrees. Any more
> or less could, and frequently did, mean death.
>
> Harry
>

I'm pretty sure that the thingy in the photo is the airspeed indicator of
the New Standard, and is the one that looks to me like an AoA indicator
marked as airspeed. IMHO, it would have worked quite well for the purpose
intended in those days (when no controller ever requested you to "say
airspeed"); but would not have been an especially accurate measure of AoA
due to the interference of the wings. In short, lousy for verifying
engineering specs, and better than a more accurate instrument for just
keeping pilots and passengers healthy and airplanes intact.

Peter