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?