On Dec 16, 9:00 am, Andre Kubasik
wrote:
I don't think a permanent display
is neccessary any more. I'd think training is better that any display can be
and being in severe and urgent trouble, a display,
be it visual or audible, might not get through to your
overloaded mind, where thorough trained and understood
things can still be present and available. regardsAndre

Andre, the nice thing about an AOA gauge is that it takes away the
need to think about weight or bank angle when maneuvering near the
stall. In a trainer, there usually isn't a lot of difference in weight
(no ballast) and with a low wingloading, it's often easier to feel the
stall coming, so low speed can be flown more by reference to feel than
actually crosschecking the airspeed indicator - which often is
misreading anyway at those low speeds. Now, move up to high
performance glass (maybe with no stall warning), add ballast, and move
to a crowded, low, narrow thermal - now there can be a significant
difference between stalling airspeed (compared to no ballast, shallow
bank, etc.) and if the pilot does not understand that the airspeed he
is using has to be adjusted for the specific (and varying conditions -
as bank angle changes) situation, it's easy to stall. Thats where the
mind gets overloaded.

OTOH, with a properly designed AOA system, you just slow down (puill)
until you are at the AOA you want, and keep it there. Easier than
airspeed, it's just attitude flying, as the AOA responds as fast as
you move the stick. Sweet, as the kids say...

The problem is simple - up to now, useful AOA systems tend to be
complicated, fragile, and powered - unlike airspeed indicators. So
they have not been developed for gliders. But you can say the same
about variometers - look at what we are now using! Nobody want to go
back to pellet varios, and most appreciate the safety factor of TE and
audio - but it took demand from the user (and contest wins) to push
their development.

Somewhat similar change is going to happen eventually with altitude
measurement and use - we still use the altimeter, when we really
should be using
GPS elevation for glides. Altimeter is great for talking to ATC and
other gliders (assuming you have a current altimeter setting) but
really doesn't show you how high you are above your destination. GPS
does. Of course, it's complicated and requires power.

Typically, a trainer (at least in the US) provides the student with
airspeed (when it should also show him AOA - what the wing is really
doing), altitude (when it should also show him elevation, so he
understands the difference), and often only rate of climb (when he
also needs to see rate of energy gain/loss, i.e. TE).

So, we train with inexpensive, pneumatic, simple instruments that
provide crude approximations of the information we really want, then
hopefully move up to complicated, accurate instruments that provide
the direct data we want (at least for vario and elevation). That's
OK, as long as the student is made aware of the difference - or he may
find out at his own peril!

Cheers,

KIrk