Performance World Class design proposal

Bruce Hoult wrote:
In article ,
"Pete Reinhart" wrote:

Mark,
A most thoughtful metric.
It might lead to a very interesting way of valueing the gider market as
opposed to $perL/D.

Of course this is just L/D at 80 knots, with his 300 fpm cutoff being
an L/D of about 26.6:1 and an LS4 being 25:1.

It appears that you need (-ve) flaps to get as low as 300 fpm, but then
there are lots of missing interesting gliders. The Discus and ASW28 may
prove me wrong, for example.

Getting lower fpms seems to also have at least one downside
too: higher stall speed. I personally would like something
like a Russia AC-4c, with a fairly low stall speed, but
with ballast too. Short wings and slow stall speed when I want it
are good. I wonder about getting one with a motor and
then just putting a big water bag in the hatch instead

30 knot stall vs. 40 knot stall is
900 vs. 1600 energy units at landing.
Almost twice as much energy to dissapate at touchdown.

Once the unballasted stall speed of a glider gets past
40 knots, I'd be a little hesitant to be "happy'
about the great penetration...
--

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Mark J. Boyd

Mark James Boyd wrote:

Getting lower fpms seems to also have at least one downside
too: higher stall speed. I personally would like something
like a Russia AC-4c, with a fairly low stall speed, but
with ballast too. Short wings and slow stall speed when I want it
are good. I wonder about getting one with a motor and
then just putting a big water bag in the hatch instead

30 knot stall vs. 40 knot stall is
900 vs. 1600 energy units at landing.
Almost twice as much energy to dissapate at touchdown.

Your arithmetic is right, but the Russia stalls closer to 40 knots than
30 knots at the weight I flew one several years ago (180 pounds with
parachute). It landed noticeably faster than a Blanik or PW5.

Once the unballasted stall speed of a glider gets past
40 knots, I'd be a little hesitant to be "happy'
about the great penetration...

There is a world of difference landing off field with a glider that
touches down at 30 knots vs 40. I've known pilots that got spooked by
the faster landings when they moved from slower speed gliders to a "high
performance" one. Landing in a field just didn't seem like a such a good
idea anymore. Training can overcome this, but some just quietly slipped
away from the sport.


--
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Eric Greenwell
Washington State
USA

Bruce Greeff wrote:



I fully plan to trade my 1971 Std Cirrus in the moment I am a better
pilot than it is a glider...

May take a looong time.

I know you are talking about performance, but let me suggest you are
wrong anyway. If you are a decent pilot, you are already better overall
than a 35 year old design; if you AREN'T a decent pilot, you really
would benefit from a better glider! The newer gliders, as John Cochrane
pointed out in a recent post, handle better (more pleasant and safer to
fly), usually have automatic hookups, and offer much more pilot
protection if the first two aren't sufficient.

Speaking as a former owner of Std Cirrus ... unless you don't have much
money, the twitchiness over 70 knots, poor stall and spin
characteristics, the poor airbrakes, and the poor wheel brake, don't add
up to a glider you should have any loyalty to when there are so many
better choices nowadays. Try a better glider - "better" isn't just about
L/D - even a 20 year old design like an LS4 is a distinct improvement.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

Eric Greenwell wrote:
Bruce Greeff wrote:



I fully plan to trade my 1971 Std Cirrus in the moment I am a better
pilot than it is a glider...

May take a looong time.


I know you are talking about performance, but let me suggest you are
wrong anyway. If you are a decent pilot, you are already better overall
than a 35 year old design; if you AREN'T a decent pilot, you really
would benefit from a better glider! The newer gliders, as John Cochrane
pointed out in a recent post, handle better (more pleasant and safer to
fly), usually have automatic hookups, and offer much more pilot
protection if the first two aren't sufficient.

Speaking as a former owner of Std Cirrus ... unless you don't have much
money, the twitchiness over 70 knots, poor stall and spin
characteristics, the poor airbrakes, and the poor wheel brake, don't add
up to a glider you should have any loyalty to when there are so many
better choices nowadays. Try a better glider - "better" isn't just about
L/D - even a 20 year old design like an LS4 is a distinct improvement.


Hi Eric

I tend to agree that one can always benefit from better equipment, irrespective
of capability. As long as the skill demands of the new equipment remains within
your capabilities. Failing which, it is worse, for you. My point is that the
primary limitation in most cockpits is the capability of the nut on the stick,
rather than the structure the stick is part of.

So - I am a reasonable pilot I guess, and able to push the Cirrus sometimes. My
point was that for the money, and considering the available fleet in my part of
the world, I have a pretty satisfactory toy for my relatively undeveloped
capabilities. I would love to buy a higher performance/more forgiving etc./newer
airplane, but I am not forgetting to enjoy and USE what I have. Consider, the
Cirrus has generally sweet handling, works well in our generally strong
conditions and is teaching me a lot about XC with very low financial risk. Sure
I have to accomodate the characteristics of the aircraft - the wheel brake is
worse than the airbrake, which is not the most powerful ever met. (so I learn to
plan carefully for outlandings) The controls are very sensitive in pitch ,
especially at high speed (so I learn precision - this is good) She is not
particularly fast, so I learn to make the most of the soaring time available.

Given that I do not have unlimited funds available, I think it is better for me
to spend as much time flying my cheap to own, and quite capable 1970s design. My
evaluation is that the quantum of experience/time/launches will benefit me far
more than being able to just afford to fly, once a month in a one generation
newer plane, or not at all in a brand new supership... If funds were no limit I
would be flying more, and working less ;-) irrespective of the mount. I would
also benefit from a better glider, all other things being equal, and I suspect
this applies to most.

Eric Greenwell wrote:
Mark James Boyd wrote:

30 knot stall vs. 40 knot stall is
900 vs. 1600 energy units at landing.
Almost twice as much energy to dissapate at touchdown.

Your arithmetic is right, but the Russia stalls closer to 40 knots than
30 knots at the weight I flew one several years ago (180 pounds with
parachute). It landed noticeably faster than a Blanik or PW5.

Not fair! The Blanik has (fowler?) flaps! :P But yes, the PW-5 was
noticably slower on landing. What's really amazing is the Sparrowhawk.
Look at the penetration and then look at the low stall speed. And
fixed gear? Amazing... I haven't flown one yet (and I missed
my chance at the Labor Day weekend at Tehachapi) but I drool...

Once the unballasted stall speed of a glider gets past
40 knots, I'd be a little hesitant to be "happy'
about the great penetration...

There is a world of difference landing off field with a glider that
touches down at 30 knots vs 40. I've known pilots that got spooked by
the faster landings when they moved from slower speed gliders to a "high
performance" one. Landing in a field just didn't seem like a such a good
idea anymore.

Agreed completely. $30k worth of glider with twice as much energy to
dissipate over ruts or rocks or a caught wing is a lot more $$$$$ of
damage. I honestly think with the excellent harnesses and cockpit
energy absorption of modern aircraft (15 years old or less), anything
landing/stalling nearly level below 40 knots will result in minor
injuries, at most. But $$$$$s of damage? That's a different
story...

Carl Herold has words about this. I suspect his conservatism in
outlandings is directly proportional to the $$$$s of glider he's
piloting. Makes the cheapo 1-26 look pretty sweet, eh? :PPPPP
--

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Mark J. Boyd

(Mark James Boyd) wrote in message

Once the unballasted stall speed of a glider gets past
40 knots, I'd be a little hesitant to be "happy'
about the great penetration...

Ahh, but the beauty of great penetration is that you are less likely
to need a slower stall speed to squeeze into a small strip!

Until you have gone XC in a ship with great legs, you cannot
appreciate the value of high performance. I don't worry about the
relatively high stalling speed of my LS6, because I have the
performance (and instruments, and discipline) to always keep a nice
big place to land in reach. Yes, I said always - I treat landing out
off an airstrip like running out of gas in a power plane - extremely
poor airmanship, to say the least! Of course, in Arizona, with a
little homework, it's really not too hard to always have some sort of
airstrip in glide range at all times. Not that I don't land out
occasionally; I average about 2 landouts a year.

One thing to think about - the days of blithely landing out in any old
patch of open land in your 1-26/PW-5/K-8 are probably going to be gone
soon (unless you live in Nebraska). Too many damn lawyers and grumpy
landowners... So you might as well have the performance to make it
comfortably from airport to airport.

Kirk