Debacle: Flight test of Diana-2

"Don Johnstone" wrote in
message ...
At 20:06 17 October 2005, Ian Johnston wrote:
On Mon, 17 Oct 2005 10:09:02 UTC, Stefan
wrote:

Hmmm... Now, you must decide: Is that glider (15m!)
'easy and safe to
fly' or do you need more than 200 hours to be able
to handle it?

200 hours in 1250 flights is quite suggestive, don't
you think?

Ian

Sorry, I don't get it. Suggestive of what?



An Air Cadet ?

It seems to me that this subject has been sufficiently beaten to death...and
beyond. Any chance we can drop it and move on to something more interesting?

SW

Glider Factfinder wrote:

How about a crap soaring pilot..9.6 mins per launch,
sums things up somewhat

Or an instructor who does primarily winch launched circuit training. (A
winch launched circuit lasting about 3 to 4 minutes on average,
depending on the place.) Of course, I haven't found more facts than you.

Stefan

At 21:36 17 October 2005, Ian Johnston wrote:
On Mon, 17 Oct 2005 21:15:29 UTC, Don Johnstone
wrote:

At 20:06 17 October 2005, Ian Johnston wrote:

200 hours in 1250 flights is quite suggestive, don't
you think?

Sorry, I don't get it. Suggestive of what?

Quite a lot, really. 9 minutes 36 seconds per flight,
on average.

Ian

Interesting, I have roughly the same average with 1540
hours and 8500 launches. I must be in-experienced as
well then.
A lot of instructors get stuck with that sort of average,
goes with the territory they don't have the opportunities
others do.
To my mind the launches (and landings) are an indication
of being able to get it right more than pure hours.

Scott Westfall wrote:
It seems to me that this subject has been sufficiently beaten to death...and
beyond. Any chance we can drop it and move on to something more interesting?

Aw Scott, I was just getting out my *big* dead-horse-beatin' stick.
;-)

Shawn

Andreas Maurer wrote:

Unless you are an engineer competent in composite design for crash
protection, I don't think you will learn anything about the design by
asking "where the Kevlar is".


Well... extremely light weight of a fuselage definitely makes me
wonder about crash protection - something Germany glider manufacturers
have a lot of experience with. I think there's a good cause why their
gliders are so heavy compared to the Diana 2.

Questions about the crash protection are very sensible, but they should
be good questions. I think "how can your glider be so much lighter than
the German gliders?" would be a much better question than "where is the
Kevlar?". Or maybe: "Is the Diana 2 crash protection as good as the ASW
27 (for example)?"

snip

The design maximum speed is Vne + 15 percent - this is what the glider
is designed for (and being flight-tested). Obviously this is the
proven speed where no flutter occurs... at least in a perfectly
maintained (prototype) glider.
I certainly wouldn't risk to fly that fast... do you think that
someone is so stupid to exceed Vne?

I can easily imagine a pilot thinking "This wave has such strong winds,
I must fly very fast to get to the upwind lenticular. The air is quite
smooth, and the actual flutter speed was determined by testing at 40
knots over Vne, so I can fly at 30 knots over Vne quite safely; of
course, I will be very gentle on the stick!"

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Eric Greenwell
Washington State
USA

On Mon, 17 Oct 2005 16:02:16 -0700, Eric Greenwell
wrote:

Questions about the crash protection are very sensible, but they should
be good questions. I think "how can your glider be so much lighter than
the German gliders?" would be a much better question than "where is the
Kevlar?". Or maybe: "Is the Diana 2 crash protection as good as the ASW
27 (for example)?"

Indeed.
The 27 is a good example because its dimensions are very similar to
the Diana 2.

I know how long it took for Schleicher to squeeze only 20 lbs out of
the forward fuselage from the ASW-27 (which then became the 27 SL with
an empty wight of 230 kg). Hard to see for me how someone is able to
save another 48 kg on a glider of similar dimensions without
sacrifying anything (the empty weight of the Diana 2 is 182 kg).

I heard that the wings of the Diana 2 are only slightly lighter than
the ones of the ASW-27, but unfortunately I didn't find more
ionformation yet.


I can easily imagine a pilot thinking "This wave has such strong winds,
I must fly very fast to get to the upwind lenticular. The air is quite
smooth, and the actual flutter speed was determined by testing at 40
knots over Vne, so I can fly at 30 knots over Vne quite safely; of
course, I will be very gentle on the stick!"

Well... definitely a proof of the existence of natural selection
then...
I could think about a different scenario with the same result:
Since the indicated Vne goes down with altitude (but the red line
doesn't move), it's easily possible to fly faster than Vne
unintentionally if one forgets to study the Vne over height (no idea
of the correct technical term in English... sorry...) limitation
table and flies at high altitude.





Bye
Andreas

On 17 Oct 2005 21:16:49 GMT, Nick Olson
wrote:

Nothing special about that except the performance so
what is so difficult. I don't hear people saying that
a Discus (1 or 2) LS8 or any of the Scheilcher gliders
are anything but straightforward providing the pilot
has received the proper training.

Don get your basic facts right matey - Diana is a FLAPPED
15m glider!!

.... and?
In my club the required total time to fly our ASW-20 was 100 hours.
Noone ever had a problem (and for all of them it was the first flapped
glider).
In my opinion the 20 is a lot harder to fly than the current 15m class
gliders (DG-800, ASW-27 and Ventus 2).

200 hours including experience on flapped gliders should be plenty to
fly any flapped glider.





Bye
Andreas

Andreas Maurer wrote:
Or maybe: "Is the Diana 2 crash protection as good as the ASW
27 (for example)?"


Indeed.
The 27 is a good example because its dimensions are very similar to
the Diana 2.

I know how long it took for Schleicher to squeeze only 20 lbs out of
the forward fuselage from the ASW-27 (which then became the 27 SL with
an empty wight of 230 kg). Hard to see for me how someone is able to
save another 48 kg on a glider of similar dimensions without
sacrifying anything (the empty weight of the Diana 2 is 182 kg).

I can only speculate, because I am not familiar with the Diana 2. I know
from speaking to Gerhard Waibel that some structure on the Schleicher
gliders is much stronger than required by the flight loads. I learned
about that when I had a problem with an aileron push rod at the root of
my ASW 20. Gerhard told me I didn't have a problem, because those rods
were three times stronger than the flight loads required, due to ground
handling issues (pilots would grab the rods to keep the wing from
tipping in a wind). Similarly, the wings are much stronger in the
horizontal direction than needed in flight, because pilots and crew put
a lot of force on the wing tips when pushing the glider around on the
ground.

If a designer believed the owners of his glider would be very careful
when moving the glider on the ground, he could save weight in these
areas (and others). Of course, there are other ways to save weight: the
SparrowHawk is an extreme example of this, and one factor is the use of
pre-preg carbon fiber instead of wet lay-up. Or, perhaps, pultruded
carbon rods instead of a roving spar cap, as some gliders use.

I don't know how the Diana does it, but if I wanted a Diana 2, I would
ask questions like "How did you achieve this weight reduction without
sacrificing strength needed for ground handling or crashworthiness?".

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Eric Greenwell
Washington State
USA

In article ,
brtlmj wrote:

On 17 Oct 2005 20:02:50 GMT, Ian Johnston wrote:
fly" or do you need more than 200 hours to be able to handle it?
200 hours in 1250 flights is quite suggestive, don't you think?

This _might_ mean that he is instructing a lot.

And on a winch, to boot.

It seems inconceivable that any pilot could have such a low average time
otherwise. I just looked at mine out of curiosity (gotta log electronic
logbooks...):

Crew Flights Time Avg
==== ======= ====== ===
P 88 115:21 79
P1 141 96:11 41
P2 102 36:28 21

I'm not an instructor. So what you can see is that my average flight
while under instruction (including subsequent two seater ratings, site
checks, and BFRs) is 21 minutes. Average flight time when taking
friends for rides is nearly double that, and average single-seater
flight times are nearly double again (I'm a bit embarassed by how low
that 79 minute number is, actually).

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