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Old February 5th 09, 05:04 AM posted to rec.aviation.soaring
Bruce Hoult
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Posts: 961
Default T Tailed Libelle?

On Feb 5, 1:26*pm, Martin Gregorie
wrote:
According to Simons the H.205's only vice was a sudden loss of height if
you closed the TE flaps since they added lift and lowered the stalling
speed: not a good thing to do toward the end of finals. I've seen a lot
of Std.Libelles (there are three on our field including my all-balsa
example, S/N 82) but I've never seen an H.205 in the flesh.


We had one at Wellington club from I don't know when until 1996 or
so. At the time I started to learn to fly you went from a Blanik to
the Club Libelle as your first single-seater. It was a big jump!! By
the time I got to that point the club had acquired a K6, which was an
excellent in-between step. I did about 60 or 70 hours in the Club
Libelle, including taking it to Omarama for recreational flying on my
off days when I was helping with the scoring at the 1995 Worlds.

The airbrakes did have a significant flap effect and lowered the stall
speed by about 5 knots. I don't know how anyone could have a problem
because of that though -- you're not going to get into trouble unless
you're flying at under the clean stall speed, which would be
insanity. Just fly your approach at clean stall speed plus 10 (plus
half the wind) and the variation of stall speed with brakes never
becomes an issue. Then go to full brakes as you come over the fence
or in the flare (if you weren't already) and you get excellent
deceleration in the air, an impressively low touchdown speed and short
rollout. It was just fantastic for doing approaches over trees, and I
found that a vertical dive with brakes open gave about 85 knots, which
was below the rough air speed.

By far the bigger problem at our field was people landing with partial
brake and getting flap effect but not much brake and floating all the
way down the runway.

Someone said it had Hornet wings. I don't believe so. The plan and
profile were as far as I could tell the same as the Std Libelle, with
only the airbrakes (and mounting position) different.

In theory the performance was less than a Std Libelle. I believe the
Club Libelle was deliberately dumbed down to get the best L/D down to
35 for the then Club Class rules (see Club Astir also). It had a much
roomier cockpit and fixed undercarriage. However it was pretty hard
to tell the difference. We had a Std Libelle as well and I flew one
or the other many times in company with the other and any difference
was tiny. I remember doing a final glide of about 30 km in the Club
Libelle, side by side with the Std Libelle, and we were maybe 50 ft
apart in height at the end.