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Update on Minden tradegy



 
 
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  #41  
Old November 5th 04, 11:16 PM
Stefan
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Todd Pattist wrote:

For high performance gliders I'm surprised no one has
mentioned that the installation of gyro instruments is
prohibited in competitions.


That's why our gyros are installed with nuts with a small hole in them,
so you can cover the iinstrument with a piece of cardboard and seal it.

Stefan

  #42  
Old November 6th 04, 03:32 PM
Mark James Boyd
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Todd Pattist wrote:

Training gliders are for training, and no one gives
instrument training in gliders that I'm aware of.


Well, we've got a T&B in our Blanik, and if I can get the
thing on power, I plan to do at least the lifesaving IMC
training in it...

At least a few glider pilots have told me they've landed after dark too,
in the horizonless desert. I myself have been in horizonless smoke
(thankfully in a glider with a T&B). I've been in that same glider
(briefly) disoriented in craggy mountains, solved by a glance at the T&B.

I suspect
there's a bit of "too expensive" and "if it's installed
they'll be tempted to use it" in there too. That said, I've
seen them in rental 2-32's and a club Blanik, but they don't
seem to be common.


The "tempted to use it" comment is apt. Despite warnings not to
practice emergency procedures solo, and signing a form to that effect,
I've had pre-license (power) students fly solo IMC and do spins
on their own. There's no substitute for (bad) judgement...

For high performance gliders I'm surprised no one has
mentioned that the installation of gyro instruments is
prohibited in competitions. Last I looked, you couldn't
even install a Cook or Bohli compass.


That these gliders then regularly don't have this equipment is
unfortunate. Is the rule really "can't be in the aircraft" or is it
"can't be operational?" One would hope the latter is sufficient.

Panel space was an issue, and I suppose there is some current draw.
And I'd expect it might be hard to find an A&P (mechamic) to install
one on a switch


More good points. If I flew at all regularly in wave, I'd
seriously consider installing a T&B, but my glider is
experimental, so I can do what I like..


From a private e-mail, one sender mentioned neither the rental 103
nor Discus he flew in Minden had T&Bs...

I want to point out to those who perhaps are considering installing
a gyro in their glider, that a Turn and Bank and a Turn Co-ordinator
are two (slightly) different things. A T&B has a gyro on a plane so it
only gives rate of turn information AND IS MUCH LESS SUSCEPTIBLE TO
TURBULENCE. The TC has the gyro slightly canted so it gets a tiny
bit of roll information displayed too. Although the TC is easier to
use for inexperienced IMC pilots (because it acts a tiny bit like a
AI), it is much less useful in tubulence, which is often when it is
most critically needed. I'm not at all a fan of a TC. Be careful
when buying something too, because modern instrument makers put
mixed displays on the gyros. If it looks like a TC (little airplane wings)
it might not be, and if it has a little needle and doghouses, it might not
be a T&B. I'd be careful at initial purchase to make sure what I got,
and then get an old hand to test fly it for you and make sure it doesn't
move on the initial roll-in or during dutch rolls...

As far as current draw, that's another thing I can't speak to.
Ultimately I suppose whether one installs a T&B is an individual decision...


Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)



--

------------+
Mark J. Boyd
  #43  
Old November 6th 04, 03:34 PM
Mark James Boyd
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Ian Strachan wrote:

This sort of training is less sophisticated than that conducted in
professional aviation, but is effective in a sport aviation environment.
IMHO.

Others have made the point that above 8/8 there is no substitute to
having at least one gyro instrument. Even the humble turn and slip
instrument will do! It's cheap, cheerful and works safely with little
battery power.


I'm glad to hear you folks over there do this. And I bet
you have few IMC related accidents, eh?
--

------------+
Mark J. Boyd
  #44  
Old November 7th 04, 12:18 AM
Ian Strachan
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In article 418cee9a$1@darkstar, Mark James Boyd
writes

snip

I want to point out to those who perhaps are considering installing
a gyro in their glider, that a Turn and Bank and a Turn Co-ordinator
are two (slightly) different things.


A T&B has a gyro on a plane so it
only gives rate of turn information


As I understand it, some of your US turn-gyro instruments have a panel
presentation from the turn-gyro not with a needle but with an aircraft.
I have seen these and think that they are seriously misleading,
particularly for the inexperienced instrument pilot.

What I mean is that they can mislead the pilot into thinking that he is
getting angle-of-bank information from the instrument when he is in fact
getting rate-of-turn from the standard Sperry 1920s design of
spring-constrained rate-gyro system. As I said in an earlier posting,
this was a simple and breakthrough system for retaining control in
cloud, but the rate gyro is just that, a measure of rate of change of
direction. More precisely, direction in the plane at right angles to
the basic spin direction of the gyro.

In my recollection, turn gyro instruments are set up in the lab so that
a rate 1 turn takes 2 minutes to go through 360 degrees. If my
recollection is right, a rate 1 turn gives a 180 heading reversal in one
minute. On "limited panel" we used to practice these as so-called
"pattern turns".

AND IS MUCH LESS SUSCEPTIBLE TO
TURBULENCE.


Compared to what, and why??

The TC has the gyro slightly canted so it gets a tiny
bit of roll information displayed too.


You will have to explain this, I do not understand.

Rate-of-Turn is related to steady bank angle, of course, but these are
not quite the same, particularly in turbulence or when recovering from
"unusual positions".

A simple Sperry-type rate-gyro instrument gives an output in
rate-of-turn whether it is by a needle (rate 1, 2, 3 etc) or a
(misleading) aircraft silhouette. The gyro spin is in the direction of
the longitudinal axis of the aircraft. Also the gyro could be made to
spin in either one way or the other (clockwise or anti-clock, of you
like). In an aircraft turn instrument, the gyro is designed to spin in
the direction so that application of "G" increases the needle indication
rather than decreases it (the so-called G-error for turn indicators).

The consequence is that if you wire up the DC to your turn indicator the
wrong way, the gyro also rotates in the wrong way and you lose its
sensitivity under G.

Such as in a spiral dive when you could pull the wings off because as
you pull the needle moves to the middle and you think that the wings are
nearly level, and so pull harder. But they ain't anywhere near level,
just think about it ......

So, fit a turn gyro instrument and make double-sure that the DC is wired
the way it was intended.

Test it by flying in VMC with the gyro on, make a steady rate 1 turn and
then pull a little G. Make sure that the needle deflects further, not
goes towards the middle. This could save your life if you ever get in
an inadvertent spiral in cloud.

--
Ian Strachan
Ex military Instrument Rating Examiner
Lasham Gliding Centre, UK


  #45  
Old November 7th 04, 11:44 PM
John Firth
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Erik mann ) writes:
(John Firth) wrote in message ...
I too learned to fly clouds, in the UK on Turn and Ball; those old gliders did
at least have speed limiting dve brakes which I never had to use.
When I graduated to the Oly with a German WWII artificail horizon
cloud flying was the proverbial piece of cake. When my AH failed
(low battery) about 12000 ft in Yugo '72, I was glad that I had those hours
Of time using T and B.
I was told that a skilled pilot with a Bohli freely gimballed compass
could adequately cloud fly and Bohlis were banned from World comps.
I did prove to my limited satisfaction that with great care and circumspection
one could maintain a controlled trun using the COOK vertcal bearing compass
but I do not think I would try it now.
In closing, always have a backup, if you go IFR; the offical report of a
sad accident to a single engine transatlantic delivery happened on final
IFR approach to Reyavik , when the pilot reported AH failure! (no T and B)
That is pegging your life to one unkown instrument.
Don't do it.
John Firth
Old, no longer bold pilot.

... which brings us back to the question of whether or not modern GPS
displays of the sort that Glide Navigator provides would be adequate
on an EMERGENCY basis to provide roll reference. Just to clarify, I
fully agree with all of the posts that intentional flight in IMC
without proper instruments is nuts. I have over the last 20 years
only a few hours of needle/ball/airspeed training and practice, and I
would never rely on it today given how rusty I am. However, it's
basically a moot point in the US, as almost no gliders are equipped
with an AH or even an electric T&B. So, in a pinch, the question on
the table is: Benign Spiral or maintain level flight (if possible)
using available instruments? My guess is that the GPS output is
probably too coarse to provide rapid enough roll information,
especially in turbulence. I think I'll go up with someone in a
two-place and give it a shot. Report to follow...

P3



The track screen on my basic Garmin GPS provides a heading arrow and speed.
The heading certainly gets up dated fast enough to control a striaght heading
and probaly a skilled pilot could use it as a turn indicator, just like like
a gyro compass; might be worth checking out for emergencies.

John Firth Old and maybe more prudent.

 




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