50+:1 15m sailplanes

Never mind

It is till a good quote

(I still think it was Moffat back in the 70s)

Robert

Bob Johnson wrote:
Just to keep stuff straight, while Mr. Moffat has certainly expessed
from time to time his fondness for span, I believe "there is no
substitute for span" quote comes from Michael Bird ("Platypus") who used
to "tinsfos" us quite regularly in S & G (Brit mag) from across the pond
...

Of course I could be wrong ..

BJ


Robert Danewid wrote:

There were 2 SZD56 flying in the worlds in Sweden in 1993. They
performed nice but not astonishing. One of them even had a minor midair.

A year later or so we had one (modified) exhibited at the Annual Swedish
Cliding Conference, and as Chris writes, the cockpit were not built for
nice looking guys from the West, but supposedly for thin, starving
pilots from the eastblock...... (now that has thank God changed!)

Moffat once wrote: there is no substitute for span! If you want 50+ go
for an 18m or larger ship, if you want nice handling, easy rigging etc,
it is easy to trade in som finesse-point to achieve that in a 15m glider!

Robert
H304

Chris OCallaghan wrote:

It's been a few years, but if memory serves Gerhard said that the 27
wing could manage a Finesse (best L/D) of 100, that is, if he didn't
have to hang a fuselage off of it. However, most glider pilots like to
fly their aircraft in the first person, so he compromised and got a
Finesse around 46. The Diana, on the other hand, took the road less
travelled by and decided that pilot comfort (or in my case, presence)
were not critical marketing factors. Based on that philosophy, I
wouldn't doubt that a determined engineer could achieve a Finesse of
50+ for a 15 meter glider. However, we've learned that best L/D is a
poor means of judging sailplane performance. It is the flatness of the
drag curves on both sides of the intersection that really determine
the worth of your glider. A polar free of a low speed bucket and
relatively flat increase of sink with speed make a great glider. Might
the poles have found a new trick? A more stable high aspect ratio
airfoil that needs less tail? A better fuselage/wing transition?
Improved laminar control? Perhaps.





Paul T wrote in message ...


'DuckHawk 15m racer announced at 2003 SHA Western Workshop.
53:1glide ratio VNE 200 kts' -from Winward Performance
- anyone got anymore details?

'SZD-56-2, Diana 2: Newest 15-meter Sailplane.The technologically
advanced SZD-56-2 Diana 2 will soar on new wings next
summer. Bogumil Beres, chief design engineer of the
Diana and owner of Biuro Projektowe 'B' Bogumil Beres,
recently announced the design project of a breakthrough
Diana 2, featuring a curved wing platform with a continuously
varying airfoil and high-performance winglets. The
original Diana fuselage will be retained, but with
a lower drag fuselage-wing junction. The wing loading
range will be 6.08 - 11.7 psf. Most remarkably, the
Diana 2 will break the long-standing 15-meter glide
ratio barrier of 50/1 with room to spa forecast
performance includes a max L/D of 52/1. The prototype
Diana 2 wings will fly next August. Diana 2's will
be delivered in the Spring of 2005.'

Have the Germans got something to worry about?

Ian, I thought your "aux vaches" was the M in Nimbus4DM......

Robert

Ian Strachan wrote:

In article , Bob Johnson
writes

Just to keep stuff straight, while Mr. Moffat has certainly expessed
from time to time his fondness for span, I believe "there is no
substitute for span" quote comes from Michael Bird ("Platypus")


I do not think that Plat would claim credit for this saying which,
regarding straight performance, has been extant in gliding since I
started in the 1950s.

It refers to the "easiest way to increase performance" (max L/D I
suppose), contrasting the relative simplicity of adding span compared to
the complexities of adding flaps, new airfoil sections, new
configurations, etc.

In my own case I remember the Grunau (about 13m I think), good in a
thermal but not in a glide, a sort of ancient PW-5. After the Grunau, I
progressed through the 15m Meise (well the UK Olympia version anyway) to
the Skylark 2 (laminar 15m) to the Skylark 3 & 4 (18m) and finally
through various syndicates from 15 to 18m to the Nimbus series, starting
at 22m and now 26 in the Nimbus 4DM, twice the span of the dear old Grunau.

As far as I am concerned, "there is no substitute for span". In UK
soaring conditions, anyway, if you wish to avoid landing "aux vaches".
Our vaches may not be very vicious but our roads (for retrieving) are
.......

The quote that I've seen attributed to Plat concerning tinsfos is
something to the effect of:
"There is a substitute for span, it's called skill, but you can buy
span"

"There is a substitute for span, it's called skill, but you can buy
span"

OK, it's 7:00 PM, the sky has been completely overcast for hours, you have
5000 feet and your looking at a 50 mile final glide. Now SKILL your way home.

A very mery Christmas to all my RAS buddies.
JJ Sinclair

JJ Sinclair wrote:

I own an honest to god, 53:1, 15 meter ship. I'm not kidding, on several
occasions the GPS trace shows I am making 100 foot per statute mile. The only
problem is, when I measure the wings, the tape reads 86 feet (ASH-25)
JJ Sinclair

With a back wind of 75 km/h this is no problem for a 15m ship.

Noël

JJ,
It is clear that, in spite of your vast knowledge of all things connected
with sailplane repair, you are using the wrong tool for the job.
When I was in the sailmaking business we had a specialized tool which we
shop fabricated for just this type of critical work. It's called a jib snap
spacing tape and you make it from half inch or inch wide batten pocket
elastic marked with indelible markers in suitable increments. In your case
I would advise 1 meter marks to make it easy.
I bet if you would use the proper tool, as suggested here, and correctly
apply it, you'll find your 53:1 glider is pretty close to the desired 15
meter span.
Here's wishing you and all of the R.A.S. community health , happiness, and
prosperity for the holiday season and the coming year.
Cheers!, Pete


JJ Sinclair wrote in article
...
I own an honest to god, 53:1, 15 meter ship. I'm not kidding, on several
occasions the GPS trace shows I am making 100 foot per statute mile. The
only
problem is, when I measure the wings, the tape reads 86 feet (ASH-25)
JJ Sinclair

JJ, negative thinking - use the force!

Robert

JJ Sinclair wrote:
"There is a substitute for span, it's called skill, but you can buy
span"


OK, it's 7:00 PM, the sky has been completely overcast for hours, you have
5000 feet and your looking at a 50 mile final glide. Now SKILL your way home.

A very mery Christmas to all my RAS buddies.
JJ Sinclair

Here's the figures on the American DuckHawk (got to
be one of the most awful names for a sailplane) from
the promo sheet.

Windward Performance LLC takes its advanced technology
to the racing class.


Specifications
Empty Weight 300 LBS
Gross Weight 900 LBS
Wing Span 49.17 FT
Wing Area 74.93 FT^2
Aspect Ratio 32.2:1
Length 20.6 FT
Horizontal Span 6.8 FT
Vertical Height 4.5 FT

Structural Limits
+11.0 / -9.0 g’s
Va, Vb = 165 KTS
Vne = 200 KTS

Performance
At 500 LBS, 6.7 Lbs/FT^2
Best Glide 50:1 at 50 KTS
Min Sink 94 FPM at 40 KTS
Stall Speed 35 KTS

At 900 LBS, 12.0 Lbs/FT^2
Best Glide 52:1 at 67 KTS
Min Sink 122 FPM at 57 KTS
Stall Speed 47 KTS
(data for 900 LBS, 12 PSF)

Airfoils
Inboard 12.7 % t/c
Outboard 10.2 % t/c


The DuckHawk has the broadest wing loading range available,
the highest maneuvering and redline speeds, and the
lowest inertias for snappy handling. The lower flying
mass within the 15m span constraint gives an induced
drag advantage of 49% at 500 LBS and 33% at 900 LBS
(span loading squared) compared to the competition


Time will tell - my money is on the Diana 2 which is
a development of the SZD-56-1 Diana. (Whose cockpit
is bigger than a Ventus a!). Incedently at Leszno they
were also talking about an 18m version and 22m Open
class version.

JJ Sinclair wrote:
"There is a substitute for span, it's called skill, but you can buy
span"


OK, it's 7:00 PM, the sky has been completely overcast for hours, you have
5000 feet and your looking at a 50 mile final glide. Now SKILL your way home.

You don't grasp the concept, JJ: with skill, the pilot is 50 miles out
at 6 pm, not 7 pm, and gets home just before all the lift dies.

Since I can't buy skill either, I bought a motor.

I seem to remember a wonderful letter in Sailplane and Gliding in which
the writer noted that, when he first started gliding in his twenties,
average glider LD ratios were around 1:20's. In his thirties, this rose
to 1;30's and, at the time of writing, in his forties, 1:40's. He was
looking forward to his 100th birthday! May be new materials, better
design will prove a substitute for span. The one thing that there will
never be a substitute for is Money. Anyone who disagrees may care to
explain the absence of K8's from the various handicapped comps.

-----Original Message-----
From: Glider Pilot Network ]
Sent: Wednesday, December 24, 2003 10:10 PM
To: Steve Hopkins
Subject: [r.a.s] 50+:1 15m sailplanes


------------------------------------------------------------
Newsgroup: rec.aviation.soaring
Subject: 50+:1 15m sailplanes
Author: Robert Danewid
Date/Time: 22:00 24 December 2003
------------------------------------------------------------
JJ, negative thinking - use the force!

Robert

JJ Sinclair wrote:
"There is a substitute for span, it's called skill, but you can buy
span"


OK, it's 7:00 PM, the sky has been completely overcast for hours, you
have
5000 feet and your looking at a 50 mile final glide. Now SKILL your
way
home.

A very mery Christmas to all my RAS buddies.
JJ Sinclair


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