50+:1 15m sailplanes

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?

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?

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
........

--
Ian Strachan
Lasham Gliding Centre
UK South

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, 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

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.

In article , Eric Greenwell
writes
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.

Even better, a motor AND good L/D. Gap-crossing can be needed any time,
not necessarily after 6 PM !

--
Ian Strachan
Gap Crossing Country (UK)

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


Now, Now, Eric we don't want to start that *motor* argument again, do we?
JJ Sinclair