WAAS GPS vario?

On Jan 14, 3:01*pm, "kirk.stant" wrote:
Embedded GPS INS (using RLG) are now standard in almost all military
aircraft - often two are used. *Neat devices; just turn it on, and in
4 minutes at most you have attitude, velocities, and position.

And GPS chips are showing up everywhere.

And MEMS gyros and accelerometers are ubiquitous in modern cars.

Could be that the hardware to make our theoretical GPS vario will soon
be less expensive than classical pneumatic varios - whether mechanical
or electronic - if the complete installation cost is compared. *What
does a really good TE system cost these days? *Probe, tubing,
installation, etc.

So my glider cockpit of the future has an AOA system, a sunlight
visible moving map/glide computer with real time weather (disabled for
contests, of course), GPS Vario, *instant-on attitude info for when
you get sucked into a cloud or trapped above a deck in a wave, ADS-B
in/out to show traffic around me, SPOT to let the family know where I
am.

And I want to be able to use voice commands to change a task inflight!

66

On Jan 14, 3:01 pm, "kirk.stant" wrote:
Embedded GPS INS (using RLG) are now standard in almost all military
aircraft - often two are used. Neat devices; just turn it on, and in
4 minutes at most you have attitude, velocities, and position.

And GPS chips are showing up everywhere.

And MEMS gyros and accelerometers are ubiquitous in modern cars.

Could be that the hardware to make our theoretical GPS vario will soon
be less expensive than classical pneumatic varios - whether mechanical
or electronic - if the complete installation cost is compared. What
does a really good TE system cost these days? Probe, tubing,
installation, etc.

So my glider cockpit of the future has an AOA system, a sunlight
visible moving map/glide computer with real time weather (disabled for
contests, of course), GPS Vario, instant-on attitude info for when
you get sucked into a cloud or trapped above a deck in a wave, ADS-B
in/out to show traffic around me, SPOT to let the family know where I
am.

And I want to be able to use voice commands to change a task inflight!

66


I've broken my triple probe once and cursed at (and fixed) O-ring
leaks in other ships, etc. but I'm still not sure I agree this is the
worst problem we need to solve. But maybe we could be moving to
simpler TE probe installations than many gliders come with. BTW a
shootout of TE probes and mounting options would be interesting.

So following Doug's points it seems that GPS doppler vertical velocity
would give very impressive resolution (ugh I should have know this -
embarrassingly I've worked on stuff related to high stability/ultra
low phase noise microwave oscillators). But I still think worrying
about doing away with the TE probe is not the right thing. Especially
since for wind purposes you still need a static + pitot so already
need (low cost) sensors for those in the unit and many pilots probably
would not want to give up a pure mechanical vario backup (or would
they?). I also suspect most people ordering new (expensive) gliders
are not going to worry about saving a little by ordering it without a
TE probe fitting and plumbing and would want the flexibility of having
that installed. If you have the air data (and can get a digital TE if
needed) then I'd hope that simple accelerometers could significantly
improve TE compensation. If GPS can also improve that then great, but
it's a complex high-end type of thing, not something that is going to
target saving costs of TE systems.

On the "less expensive" theme... you run into an common dilemma with
claiming simplicity/cost savings with new technology. To realize that
savings they have to take risks and suffer incompatibility with how
things work now (e.g. not install a TE probe system in a new glider?
Not have a TE probe etc. to also feed to a mechanical vario...). And
the cost of developing a new advanced system is likely to be
significant, so it is likely going to be something you need to target
at the higher end/performance market, with really visceral benefits
like providing for radically better wind calculations, much better
gust isolation, etc..

So while we are dreaming about possible varios/flight computers here
is my blue-sky feature wish list for a vario/flight computer/logger
-- an evolved, up to date technology version of something like the
Cambridge 302... and I'm completely biased and just want a vario/
logger/basic computer to interface to an external PDA, PNA or ClearNav
etc. not a device to navigate etc. on.

- Direct reading/pressure based (i.e. not flow rate based, no capacity
flask, etc. needed,as done in some several current designs)

- Digital TE compensation to remove the need for a TE probe, or to
tune the TE probe response as done in some current systems)

- Low power consumption.

- Good reliability (we have lots of glider instruments with sloppy
electric or mechanical design that directly affects reliability.
Starting with the corrosion/handling damage prone daughter card/rear
panel connector mess that some vendors use.).

- ICG approved logger, for everything, built-in ENL support for
motorgliders.

- A development team who can actually provide support and enhancements
for the product.

- Selection of audio tones/styles (including simulate some popular
audio vario tones. Anybody like the Rico?).

- The supplied external speaker if one is needed is not a piece of
crap (just about all of them seem to be).

- Support better wind calculation than typical today: Including 3D
Fluxgate magnetometer enhanced wind calculations. Remote mount (e.g.
down the back of the fueslage?) the fluxgate if needed. The main
intent is to hand all this stuff off to a PDA but on board
calculations of wind as a backup is nice. This may add significant
cost.

- Decreased horizontal gust sensitivity with accelerometer based
filtering/enhancement. I'd hope fairly simple MEMS accelerometers
should be enough for this with no need for anything more complex. If
GPS can enhance this significantly and be affordable and work reliably
(steep banks, next to stepp terrain) etc. then great.

- Make sure the advanced stuff does not get in the way, the thing is
stupid easy to use and just works, push complex things off to PDA
software or other devices. Logging just starts and stops
automatically, with absolutely no effort/problems.

- Enhanced IGC file logging, allow things like TAS data, fluxgste
data, (and many more) to be recorded to the IGC log file (like
apparently LX does).

- Support dual log files with different parameters, sample rates etc..
Massive IGC log files that can contain extra stuff and a smaller also
valid IGC file for uploading to OLC etc.

- Use latest generation GPS+WAAS receiver technology for improved
signal quality/fix times etc.

- Support gobs of flash memory for flight traces. Even club ships
should never need to overwrite a flight trace during a season, etc. at
reasonable log rates.

- Allow very high rate logging rate for beautifully smooth flight
traces for pretty post-flight analysis.

- Voice announce (needs to be multilingual) for warnings such as gear
up, slow speed/stall etc. Too many stupid beeps in the cockpit
already. Female voice would be great, just don't make her sound like
my ex :-)

- Have a variant of the device intended in headless operation (remote
mounted with no dial/etc on panel for use where a PDA or other
display will show a representation of the vario needle and averager
etc.

- Try to make the log data survive a crash. We've had a few
unexplained fatal accidents where the logger does not survive and I
wonder if something simple could be done in an attempt to make the
data more likely to survive. e/g. Consider dual logging to onboard
memory and a backup SD card plugged into the vario in a protected
slot.

I'd especially like to see lots of connectivity, e.g. possibly
consider things like the following...

- Utilize standard IGC RJ-45 connector wiring (All connector choices
have issues, but there *is* supposed to be a standard).

- Built in Bluetooth serial port profile support, in addition to
legacy RS-232 serial ports, to drive external PDA and PNA devices.
Could support dual Bluetooth connections for two-seat gliders.

- USB Host support for file transfer, make the logger look like a disk
drive and downloading IGC files just drag and drop from a laptop. Real
USB support not a built-in USB to serial adapter pretend stuff some
vendors ship today.

- Could also consider USB OTG support - i.e. support USB client for
connecting a Laptop or USB host for connecting to a PDA for high-
speed file/waypoint/firmware updates etc.

- Support for Bluetooth file exchange (flight traces and waypoints
etc.). This works with many laptops and PDAs and is likely a very easy
for people to use if they have a Bluetooth capable Laptop or PDA and
speeds are probably OK until you get to huge log files.


Thing's I'm not sure would work ...

- More advanced AHRS/INS technology. Why do we need this? If you want
a T&B or attitude indicator I think these are different devices and we
are better off leveraging the larger market for experimental and light
sports instrumentation.

- A built in AOA meter? But maybe I'd consider a warning/alarm? Has
anybody shown AOA displays to be useful in gliders? For stall warning?
For thermalling/flight optimization? It might be useful with voice
annunciations/warnings? (too many things beep already) - A vario/
computer could integrate an AOA sensor into slow speed/stall warning
and that could be great. The safeflight AOA instument is just a meter
right?, with no audible alarm? - they seriously want to add another
thing the pilot has to look inside the cockpit?

- Some people are playing with enhanced TE probes that try to align
with the airflow, the mechanical complexity worries me. Not sure how
significant the problem they are trying to solve is. That would be
something interesting to see more info on.

---

It hurts to think about the development effort/cost of something like
this but I'll be dissapointed if we don't see some of these more
advanced features in devices in the next few years.


Darryl