ASW20:
The A model and F model are essentially identical. The F was built
in France under licence.
Gross weight 454Kg.
Wortmann FX62 131 at root (actually the 15.3 % version tapering to
14.4% at end of taper break), becoming FX60-126 at tip.
Some late A models got a gross weight increase if the fuselage was
light enough. As high as 508 Kg I think.
The B model has a gross weight of 525Kg and the lower wing surface
was changed to be thicker aft to encourage more laminar flow. To
prevent laminar bubbles blow hole turbulators were installed.
Stainless steel or mylar foils were used also to seal the control
surface gap on the bottom. Significantly higher empty weight due to
extra structure and less bendy wings as a consequence.
The C is the same but with the extra structure to cope with the
higher weight removed so the empty weight is lighter and weight was
the same as the A model. I don't know if any C models ever got
approval for a higher than 454Kg gross.
I'm not sure the wing lower surface mods did anything for
performance. That wing as built was a fair way from what Schleicher
intended. Ron Sanders got the drawings and fixed up his 20B and did
the correct leading edge. Seemed to be a little better.
On the 20B I flew in Texas in 1986 Rick Wagner had fitted a tail
tank. I was sceptical until I flew it half full one day and filled it
up thereafter. Also putting mylar seals on the top of the control
surfaces helped. Felt much more solid in thermals.
I talked with Rick a couple of times about his ASW20 mods. He used to
have a photo of tuft comparisons on his workshop wall.
The standard downturned tips are terrible. I don't think any current
designs have them. I removed them from my Mini Nimbus and substituted
ones more like the LS4 and what Rick did but before I learned about his.
Better wing root fairings are a good idea, particularly extending the
fairing forward at the leading edge. Look at the nacelle/leading edge
fairings on a P-38. Or a Salto.
As ever, the biggest problem is finding out whether the mods really
make much difference.
Mike
At 08:58 AM 7/05/2013, you wrote:
Since all the ASW20BHs have passed their time as an H, isn't the
biggest performance difference between stock ASW20s the MGW of the
20B? Doesn't mean much at reference weight.
Heard of people who have removed the pitots, put the turbulator tape
over the blow holes of the C.
There's a "Frankenglider" or two with the great combination C
fuselage and A wings.
For those unfamiliar, the ASW20BH was the limited time at a
higher red line "Hobbs Special", all low serial number B models
raced in the '83 Worlds.
Of course, the best 20s are not as they came from the factory,
but ones modified by Rick Wagner. All the ASW20s he saw were EXP.
Rick's recipe:
Cut off inner end of flaps, bond to the wings.
Build better wing root fairings. Think ASW27 with the fairing
extending forward of the leading edge to the canopy rail.
Cut off outer end of ailerons.
Cut off wing tips. Discard.
Build new wing tips. (looked between the LS-4 and original ASH26E curved tip)
If it doesn't have a tail tank, add one.
Modify the trailer so the wing root fairing fits in the roof and
clears the floor, and adjust tip hold downs.
Wil Scheuemann's recipe was more like:
Remove skin of outer trapezoid.
Replace with same airfoil as inner panel.
That would probably spin like a top if you didn't behave, but go
like a bat out of hell.
But unlike H301 Libelles, there are no Scheuemannised ASW20s, with
or without Sebastian Kawa.
All those ideas were pre- wingletty things.
Unfortunately the best example of Rick Wagner modified ASW20s was
destroyed a while ago. Believe Rick's wingtip moulds have been
lost, and none of the other modified 20s have all the mods. One has
the aileron, flap and tip mod but not the last version of the fairing.
Jim
From: Adam Woolley <[email protected]>
To: Discussion of issues relating to Soaring in Australia.
<[email protected]>
Sent: Monday, May 6, 2013 2:52 PM
Subject: [Aus-soaring] ASW20's
If four ASW20's, one of each variant (a, b, c, f) were put in
perfect in flight test flying factory conditions - all with the same
reference weight of 400kg.
Which one would out perform the other? Or, would they all perform identically?
Keen to hear reasoning if one knows the answer (I don't, hence the Q).
Cheers,
WPP
_______________________________________________
Aus-soaring mailing list
<mailto:[email protected]>[email protected]
To check or change subscription details, visit:
<http://lists.internode.on.net/mailman/listinfo/aus-soaring>http://lists.internode.on.net/mailman/listinfo/aus-soaring
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
