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......................

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 |

When dealing with AoA sensors it is very important to consider how it
is to be used. If it is intended to be a Go - NoGo stall warning
device, that is one thing. If it is intended to be used to measure
and be proportional to a range of AoA that is quite another. The
mounting becomes quite critical because the airflow may be such that 1
degree of AoA change does not translate into 1 degree of sensor
movement (in the case of a vane for example) . As a young flight
control engineer I learned this the hard way when an AoA vane mounted
near the nose of a test vehicle actually changed 5 degrees for every
degree of AoA change of the aircraft.

Greg

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.

Hi Bill,

It is a very interesting device. I looked at it very closely at the SSA
Convention in the past. I was impressed with the high quality of the
system. If I remember correctly it includes a low friction rotating vane
that is mounted to the side of the fuselage and a variometer like meter that
is mounted in the instrument panel. I don't recall whether or not it had an
audio output. It looked very cool. I don't remember the price, but I do
remember thinking that very few glider pilots would pay the somewhat high
price. Also, it required a hole in the side of the fuselage.

Paul Remde


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