Glider angle of attack indicator by SafeFlight

I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels

On Thu, 6 Dec 2007 15:28:23 -0700, "Bill Daniels"
bildan@comcast-dot-net wrote:

I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Hope it works out. A design for an AoA indicator appeared in _Soaring_
twenty or thirty years ago, but it was really crude. IIRC, it had its
own separate pitot and static sources, and connected them across a
vertical, tapered tube similar to one side of a pellet vario. A solid
metal ball rode in the tube, its mass serving to sense acceleration,
and its vertical position gave a measure of AoA.

The vane types found on jets work splendidly, but they're mounted high
up on the airplane where people and vehicles don't bump into
them...the equivalent on a glider wouldn't last long!

I presume the Safeflight device uses the pitot/static/acceleration
principle...that should be relatively easy with contemporary sensor
technology and chips.

rj

On Thu, 06 Dec 2007 16:25:30 -0700, Ralph Jones
wrote:

On Thu, 6 Dec 2007 15:28:23 -0700, "Bill Daniels"
bildan@comcast-dot-net wrote:

I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Hope it works out. A design for an AoA indicator appeared in _Soaring_
twenty or thirty years ago, but it was really crude. IIRC, it had its
own separate pitot and static sources, and connected them across a
vertical, tapered tube similar to one side of a pellet vario. A solid
metal ball rode in the tube, its mass serving to sense acceleration,
and its vertical position gave a measure of AoA.

The vane types found on jets work splendidly, but they're mounted high
up on the airplane where people and vehicles don't bump into
them...the equivalent on a glider wouldn't last long!

I presume the Safeflight device uses the pitot/static/acceleration
principle...that should be relatively easy with contemporary sensor
technology and chips.

Oops, no, I see on the website that it uses a vane. That's likely to
be a problem...

rj

"Ralph Jones" wrote in message
...
On Thu, 06 Dec 2007 16:25:30 -0700, Ralph Jones
wrote:

On Thu, 6 Dec 2007 15:28:23 -0700, "Bill Daniels"
bildan@comcast-dot-net wrote:

I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Hope it works out. A design for an AoA indicator appeared in _Soaring_
twenty or thirty years ago, but it was really crude. IIRC, it had its
own separate pitot and static sources, and connected them across a
vertical, tapered tube similar to one side of a pellet vario. A solid
metal ball rode in the tube, its mass serving to sense acceleration,
and its vertical position gave a measure of AoA.

The vane types found on jets work splendidly, but they're mounted high
up on the airplane where people and vehicles don't bump into
them...the equivalent on a glider wouldn't last long!

I presume the Safeflight device uses the pitot/static/acceleration
principle...that should be relatively easy with contemporary sensor
technology and chips.

Oops, no, I see on the website that it uses a vane. That's likely to
be a problem...

rj

Note that they say the vane is removable. You would probably install it as
you would a TE probe just before flight and remove it just after landing.

Bill Daniels

If this works as advertised, it could be very useful, IMHO. Though I
don't see that they included and audio warning, something I think
would be essential to be useful in stressful situations.

I doubt any pilots deliberately get into stalls and spins by
deliberately flying bellow the required airspeed. Rather, if they had
known or been warned without having to look at the panel, they
probably would have sped up and remained out of the stall range.

So if they didn't notice the airspeed indicator display on the panel,
they probably won't notice an AoA indicator warning them either,
unless there is heads up an audio warning.

Come to think of it, another solution to stall spins could be
installing an audio warning on the airspeed indicator, when the speed
falls bellow a target speed, that could be adjusted based on wing
loading........

These could be simple effective pilot aids......................

Actually, I think SafeFlight's brochure says it has an audio stall warning.

Bill Daniels


"tommytoyz" wrote in message
...
If this works as advertised, it could be very useful, IMHO. Though I
don't see that they included and audio warning, something I think
would be essential to be useful in stressful situations.

I doubt any pilots deliberately get into stalls and spins by
deliberately flying bellow the required airspeed. Rather, if they had
known or been warned without having to look at the panel, they
probably would have sped up and remained out of the stall range.

So if they didn't notice the airspeed indicator display on the panel,
they probably won't notice an AoA indicator warning them either,
unless there is heads up an audio warning.

Come to think of it, another solution to stall spins could be
installing an audio warning on the airspeed indicator, when the speed
falls bellow a target speed, that could be adjusted based on wing
loading........

These could be simple effective pilot aids......................

Stall warnings in gliders have always been a problem because we tend
to fly very close to stall a large percentage of the time, i.e.
Thermalling. We don't want the stall warning going off all the way
through the climb.

I agree that most stall spin accidents are cause by inadvertantly
flying to slow and the pilot not realizing they are doing it. I also
agree that an AoA indicator won't help unless it has method to get the
pilots attention.

Perhaps disabling the warning when the gear is retracted would have
some value. Anyone know how many stall spin accidents occur with the
gear extended vs retracted?

The other issue with an AoA indicator is How does it compensate for
Flaps. The Stalling AoA will change radically as flaps are applied. I
am sure this can be done but are any of the AoA indicators available
doing it?

Brian CFIIG

Bill Daniels wrote:
I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Bill Daniels


I don't know if there was a Soaring article ever written on it, but I
know Dick Johnson had a stall indicator mounted over the wing root on
his Ventus. It was a small flat pivoting plate that "flew" in the
airstream and would stall itself close to the wing stall angle. Maybe
Dick can give some more info, maybe a picture, maybe there was an
article someplace.

Bill Daniels wrote:
"Ralph Jones" wrote in message
...
On Thu, 06 Dec 2007 16:25:30 -0700, Ralph Jones
wrote:

On Thu, 6 Dec 2007 15:28:23 -0700, "Bill Daniels"
bildan@comcast-dot-net wrote:

I was very pleased to see the advert in the December issue of "Soaring
Magazine".
See: www.safeflight.com

Does anybody know more about this device - especially the price?

Hope it works out. A design for an AoA indicator appeared in _Soaring_
twenty or thirty years ago, but it was really crude. IIRC, it had its
own separate pitot and static sources, and connected them across a
vertical, tapered tube similar to one side of a pellet vario. A solid
metal ball rode in the tube, its mass serving to sense acceleration,
and its vertical position gave a measure of AoA.

The vane types found on jets work splendidly, but they're mounted high
up on the airplane where people and vehicles don't bump into
them...the equivalent on a glider wouldn't last long!

I presume the Safeflight device uses the pitot/static/acceleration
principle...that should be relatively easy with contemporary sensor
technology and chips.

Oops, no, I see on the website that it uses a vane. That's likely to
be a problem...

rj

Note that they say the vane is removable. You would probably install it as
you would a TE probe just before flight and remove it just after landing.

Pity they don't say which sensor they use on the glider AOA instrument.
If its the type with 360 degree rotation, it could easily be using an
optical sensor (Grey encoded rotary position sensor or similar), in
which case the system could be quite robust and friction-free,
especially with a removable vane.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

DG has a stall warning incorporated in the DEI-NT with a stick shaker
option. I don't know how well it works yet. It is adjustable--(calibrated)
in flight by the pilot.
Cambridge 302 has a "too slow" aural warning, adjusted for mass and g-load
by the internal microprocessor. It does work pretty well.

--
Hartley Falbaum


"Brian" wrote in message
...
Stall warnings in gliders have always been a problem because we tend
to fly very close to stall a large percentage of the time, i.e.
Thermalling. We don't want the stall warning going off all the way
through the climb.

I agree that most stall spin accidents are cause by inadvertantly
flying to slow and the pilot not realizing they are doing it. I also
agree that an AoA indicator won't help unless it has method to get the
pilots attention.

Perhaps disabling the warning when the gear is retracted would have
some value. Anyone know how many stall spin accidents occur with the
gear extended vs retracted?

The other issue with an AoA indicator is How does it compensate for
Flaps. The Stalling AoA will change radically as flaps are applied. I
am sure this can be done but are any of the AoA indicators available
doing it?

Brian CFIIG