50+:1 15m sailplanes

(Mark James Boyd) wrote in message news:3ffef018$1@darkstar...

Hmmm...it also strikes me that weight is very important to this discussion.
A 100# solo pilot is probably not getting the best performance for the
dollar from a DG-1000.

It's not the weight of the pilot, it's the weight of the plane that
counts. That's what ballast is for. Sure, you could build a 99/100th
scale DG-1000 just for the 100 lb pilot - but why? And it wouldn't be
cheap!

What I'd want is a minimum wing loading that, with me as the pilot,
supported a polar I like. What polar I like depends on the
conditions I fly in (floater or penetrator). I wouldn't want
to have to add ballast for every flight to get the polar I normally
like, since this would mean I paid for too much wing.

The problem with this approach is that you are tailoring your glider
to one specific condition - and give away the wonderful game of
tailoring a glider's wingloading to the actual condition you are
flying in. A floater in the spring is nice, but is no fun in the
middle of summer when 10 knotters roam the desert and you need an IFR
clearance to climb to cloudbase! BTW, that is probably a big part of
the PW-5 problem - too much of a one-trick pony...IMHO.


Having picked the wing loading, I'd now buy the highest aspect ratio
I could afford. As technology advances, this means I get more
and more span.

But technology for reducing weight seems to have outpaced
technology for increasing aspect ratio. So at the end of this
discussion, I'd like a Sparrowhawk for the dollar, instead of
something else. I'd prefer a much lighter glider with a
shorter wingspan and no ballast to a heavier one with more
span and the same aspect ratio.

I actually like LESS wing area with the same loading as my ideal
polar. Because the min sink part of the polar is 20 to 100 ft/min
less, the high speed part also gains this advantage. At the
super light weight, we can use a MUCH slicker airfoil and get the
same stall speed as a glider twice the weight. And we don't have
to beef up the fuse for heavy wings, then make the
wings larger for the weight, etc... (diminishing returns).

The tough decisions a is retract worth the extra weight? And is
the glider sturdy enough to be flown in/out of typical strips
at my skill level (bumps and ruts included)? The Sparrowhawk
is an excellent concept theoretically, but is it sturdy?
As a very lightweight pilot, I'd be very interested in a
similarly light glider, but I sure wouldn't want to BREAK it.
Tiny main and tailwheels, and a fragile tailboom, can be a
real practical drawback...

The whole Sparrowhawk thing scares me to death! When I'm bashing
around at 130 knots, I want my glider to have a certain structural
authority! Same thing when landing on some strange desert airstrip
for the first time. And don't get me started on the whole unregulated
ultralight glider thing!!! IMPORTANT SAFETY TIP FOR ANY NON-LICENCED
"PILOT" DROOLING OVER A SPARROWHAWK BROCHU Get the training, take
the damn test, get a licence, and fly a real glider, for goodness
sake! Or at least make me the beneficiary on you life insurance
policy...

As a very lightweight pilot, you have the advantage of an even greater
wingloading spread available to use, which can be a nice advantage
early in the season or late in the day - why give it away?

It sure is fun to browse all the exciting equipment at each extreme...

You're damn right about that! And congratulations on your CFIG, BTW!

Kirk
A not very lightweight pilot

Kirk Stant wrote:

The whole Sparrowhawk thing scares me to death! When I'm bashing
around at 130 knots, I want my glider to have a certain structural
authority!

Why do you think the SparrowHawk doesn't have "structural authority"?

Same thing when landing on some strange desert airstrip
for the first time.

Are you suggesting that the 15 meter LS-6 you fly would be easier to
land safely than the 11 meter SparrowHawk? Why would that be? Besides
being a lot smaller span (an asset when landing out, I think), the
SparrowHawk I flew landed slower than the 15 meter gliders I've flown.

And don't get me started on the whole unregulated
ultralight glider thing!!!
IMPORTANT SAFETY TIP FOR ANY NON-LICENCED
"PILOT" DROOLING OVER A SPARROWHAWK BROCHU Get the training, take
the damn test, get a licence,

Excellent advice, and echos what SparrowHawk people recommend.

and fly a real glider

I beg your pardon, but what isn't "real" about the SparrowHawk? From the
FAA registration database:

N-number : N40437
Aircraft Serial Number : 004
Aircraft Manufacturer : COLE GREGORY M
Model : SPARROW HAWK
Aircraft Year :
Owner Name : COLE GREGORY M
Owner Address : 2988 NE ROCKCHUCK DR
BEND, OR, 97701-6515
Type of Owner : Individual
Registration Date : 12-Jun-2003
Airworthiness Certificate Type : Not Specified


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Eric Greenwell
Washington State
USA

Eric Greenwell wrote in message ...

I beg your pardon, but what isn't "real" about the SparrowHawk? From the
FAA registration database:

N-number : N40437
Aircraft Serial Number : 004
Aircraft Manufacturer : COLE GREGORY M
Model : SPARROW HAWK
Aircraft Year :
Owner Name : COLE GREGORY M
Owner Address : 2988 NE ROCKCHUCK DR
BEND, OR, 97701-6515
Type of Owner : Individual
Registration Date : 12-Jun-2003
Airworthiness Certificate Type : Not Specified

Eric,

Sorry, no disrespect intended, in your case the N number absolutely
makes it real. I have no problem with a registered glider flown by a
licenced pilot, which is obviously what you are - and from what I've
read it sounds like you are having a lot of fun. My fear if for the
unlicenced pilot flying an unregistered (or deregistered?)
Sparrowhawk. That is a dangerous situation, in my opinion. Push the
Sparrowhawk as a 1-26 replacement - or the saviour of fun soaring in
the US, fine, go for it!; sell it as an ultralight that "anybody" can
fly is scary! And sure, the manufacturer can insist on training, but
what happens when that Sparrowhawk is resold? Off comes the
N-number...

I guess I should shut up until I've been able to put my grubby little
paws on a real live Sparrowhawk. Or better yet a Duckhawk - can't
wait to fly against one of those and see if it is really a
breakthrough concept! Time - and a few competitions - will tell!

Kirk

Kirk Stant wrote:

Eric,

Sorry, no disrespect intended, in your case the N number absolutely
makes it real. I have no problem with a registered glider flown by a
licenced pilot, which is obviously what you are - and from what I've
read it sounds like you are having a lot of fun.

I don't own one, but I have flown one a couple of times, and have talked
with a couple of the owners quite bit.

My fear if for the
unlicenced pilot flying an unregistered (or deregistered?)
Sparrowhawk. That is a dangerous situation, in my opinion.

Not if the pilot is competent, of course, but I think I know what you
mean: potentially, the pilot might be untrained and outside the usual
network of oversight, such as biennials. Windward Performance knows
this, and if you look at their website, you will see that they don't
push this aspect of the glider. Windward Performance wants this to be a
successful glider, and crashes are bad news.

Push the
Sparrowhawk as a 1-26 replacement - or the saviour of fun soaring in
the US, fine, go for it!; sell it as an ultralight that "anybody" can
fly is scary!

As I said, they don't do this. Remember that Greg Cole, the designer,
makes his living designing real aircraft (e.g., he was the principal
engineer on Lancair's certified Columbia 300 and currently consults for
Adam Aircraft). It's my understanding every current customer will be a
licensed glider pilot by the time they take delivery (most of them were
before they ordered one, anyway).

Practically speaking, it's expensive enough that it's very unlikely that
an inexperienced person is going to by one, anyway.

And sure, the manufacturer can insist on training, but
what happens when that Sparrowhawk is resold? Off comes the
N-number...

If someone wants to fly, say, a 1-26 without a license or training,
there is little to stop them. Buy one, take it to dry lake, and car tow
it. Determined ignorance, stupidity, or arrogance can easily work
outside the system.

I guess I should shut up until I've been able to put my grubby little
paws on a real live Sparrowhawk. Or better yet a Duckhawk - can't
wait to fly against one of those and see if it is really a
breakthrough concept! Time - and a few competitions - will tell!

I'm waiting until they have a chance to put that motor in the SparrowHawk...

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Eric Greenwell
Washington State
USA

On Sun, 11 Jan 2004 09:40:25 -0800, Eric Greenwell
wrote:



I'm waiting until they have a chance to put that motor in the SparrowHawk...

Take a look at the movie clip of the Silent IN with the Jet engines. I
ran some numbers on the engines over the weekend and I'm convinced
I've seen the future of soaring.

Mike Borgelt

In article ,
Mike Borgelt wrote:
On Sun, 11 Jan 2004 09:40:25 -0800, Eric Greenwell
wrote:



I'm waiting until they have a chance to put that motor in the SparrowHawk...

Take a look at the movie clip of the Silent IN with the Jet engines. I
ran some numbers on the engines over the weekend and I'm convinced
I've seen the future of soaring.

Mike Borgelt

I've come to much the same conclusion as Mike. I'd use a single
more powerful turbine (maybe the 1500) instead of 2, but
the numbers seem to work for even fairly short fields.

The heat on the tail scares me though. Hmmm...how do we
get rid of the glider tail?

On 11 Jan 2004 14:39:20 -0700, (Mark James Boyd)
wrote:

The heat on the tail scares me though. Hmmm...how do we
get rid of the glider tail?

Why would you want that?
Many have tried it, an noone came even close to a conventional layout
(the compromise design Genesis was the only one that offered similar
handling wualities and performances as a conventional glider).

Having no tail is less of an advantage if your wing has twice the
drag...
Bye
Andreas

On 11 Jan 2004 14:39:20 -0700, (Mark James Boyd)
wrote:

In article ,
Mike Borgelt wrote:
On Sun, 11 Jan 2004 09:40:25 -0800, Eric Greenwell
wrote:



I'm waiting until they have a chance to put that motor in the SparrowHawk...

Take a look at the movie clip of the Silent IN with the Jet engines. I
ran some numbers on the engines over the weekend and I'm convinced
I've seen the future of soaring.

Mike Borgelt

I've come to much the same conclusion as Mike. I'd use a single
more powerful turbine (maybe the 1500) instead of 2, but
the numbers seem to work for even fairly short fields.

The heat on the tail scares me though. Hmmm...how do we
get rid of the glider tail?


The guys with the Silent don't seem to have a problem with the heat on
the tail - the two AMT 450 turbines seem to be mounted parallel to the
centerline. If this still worries you a V tail as on HP gliders or the
Salto is the easy answer.

I first thought of using the AMT1500 but when you do the numbers two
AMT450s (and soon the XP versions with about 10% more thrust) are
quite adequate for a 400kg glider. 50 feet at 500m takeoff run under
standard day sea level conditions seems doable, over 500 fpm rate of
climb at about 90 knots, single engine out climb of close to 200fpm at
70 knots. It makes a pretty good sustainer. (A real "turbo"!) Fuel
consumption on one engine is about 0.5kg/min , two is 1kg/min. Given
that a 2000 foot launch will only take about 4 minutes it is about as
fuel efficient as a launch behind a Pawnee.

Imagine self launcher with engine out capability and a decent climb
speed where you have significant energy for manouever even if both
engines fail!

Don't worry about ducting - extend the engine(s) on a short pylon.
They weigh so little and don't vibrate that this will be a very
lightweight structure, easy to extend and retract, solves any local
structural heat problems and the hole in the glider is so small, that
there will be minimal structural reinforcement required. The AMT 450
is 5.1" diameter and 10.7" long and weighs about 2.4kg (5 pounds or
so).

Great for motorising motorless gliders as the weight in the fuselage
is minimal. Convert part of the water tanks/bags for jet
fuel.60Kg(75liters) will give you one hour.

Now look at a Sparrowhawk

70kg empty

add say 10 kg for 1 x AMT450XP pylon and structural reinforcing

30 kg for 1 hours fuel.

add typical say 100 kg for pilot and chute etc

Only 210Kg!

One AMT 450 will self launch this adequately.
Two smaller engines may still be optimum for slightly increased thrust
and engine out capability.

Hope the Windward Performance guys have a plan to increase production
because if this works they might be swamped by customers.


These small turbines are still being developed - they will get better.
Engine pressure ratios are still only 4:1 or so, fuel consumption can
be improved.

Mike Borgelt

Mark James Boyd wrote:

snip
The heat on the tail scares me though. Hmmm...how do we
get rid of the glider tail?

Duhhhhh... run the jet engine a little too long!? :-)

On Mon, 12 Jan 2004 07:46:52 +1000, Mike Borgelt
wrote:


Take a look at the movie clip of the Silent IN with the Jet engines. I
ran some numbers on the engines over the weekend and I'm convinced
I've seen the future of soaring.


Search for a glider called "Huetter 30 TS"... (look here, for example:
http://vintagesailplanes.de/Huetter30TS.htm). First flight was in
1960.

It later became the Libelle and Salto... but it failed miserably with
the turbine engine although it was a very good glider. Noise, fuel
consumption and bad climb rates were the killer factors.


Bye
Andreas