SEN Feb. 8 2000

News and Reports 2000 - First half
SCAT Electronic News 8 Feb 2000

      "SCAT - 40 Years of FAI Free Flight Competition"

Table of Contents
Wet Wings ? - King
Silver Brazing - Andresen
Silver Solder - Kowal
King re-Kalacuated - King
Wire for F1A - Ackery
Re: the other Americas Cup - Ackery
Ike [and Max] Hype

Wet Wings ?
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Dear Roger,

I observed a really strange phenomena, flying to Tel Aviv last week. I was
on a Boeing 777 and this is what happened. We took off from Heathrow in
dry sunny conditions (Temp. ca 40/45 F). For the 1st 15 or so minutes
after take off, the port wing, (only, as far as I could see), became soaked
with what looked like
water !!! Not the usual vortices from tips and flaps that you get in some
damp conditions, but a continual torrent of the stuff over the whole wing.
It looked as if we were flying through torrential rain but it was dry and
sunny ???? It was as if the pilot had activated some kind of spray device
from the LE of the wing. The 'water' formed a thin layer which showed up, to
perfection, all the boundary layer effects, such as the vortex generators
etc. and poured off the TE in a wake about 1 to 2 ft thick There must have
been 100's of gallons of the stuff. You could even see how the layers, very
close to the surface, were traveling very slowly compared to the outer layers
of the boundary layer. Of course I was fascinated with the free show and
watched every effect with interest, but the big question was: What the hell
was happening?? I thought, maybe it was something related to the de icing
system, although it had not been cold enough at ground level, to freeze.
At one stage I even wondered whether, as it is quite a new design, they were
actually running some kind of flow visualization test and were photographing
the results.

The Jewish Rabbi, in the next seat noticed it also. After 1/4 hr or so,
it all stopped but when we made our approach into Tel Aviv, the Rabbi, who
could see better than me out of the starboard side, said. "Hey! you won't
believe this but it has started again" !!! but this time on the other wing

I am totally mystified, as I have never seen anything like this before
over 1000's of hours in the air. Can anyone out there, from Boeings maybe,
shed any light on this weird event?

Talking of weird events, did anyone see this one in a million chance
photo of a fighter at the moment of reaching Mach One. I enclose the photo,
which is truly extraordinary, as an attachment. Enjoy !!!!!!

Peter King

[Peter's attachment will be sent under separate cover]

Silver Brazing
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Hope this is in the right format so you don't have to redo.

One step beyond Ken's fine silver solder comment for stainless is what we
called silver solder in the aerospace instrumentation game. Guess it's
technically silver braze. It was 45% silver (10 to 20 times that of 440 deg
F stuff) and melted @ 1150F with remelt a bit higher due to disolving some
of the parent material. This is plenty doable in small sizes with Prepo & a
breeze with MAPP. Stuff was EZ FLO 45 tho others are available @ welding
supply places. Incidently, the dull red temp doesn't degrade stainless

The trick with either is to degrease, clean surface oxide with fiberglas
erasure or... then use a suitable (strong) flux. Heat joint to above solder
melt point, touch with solder, watch it wick in, making a professional
looking joint. So foolproof even an Inguneer could do it.

Others crimp soft tubing for the joint, or use Spectra inside Teflon or
stainless tube. Spectra in stainless is really slick.

Except for razor blades, stainless is really great stuff.


Silver Solder
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As I mentioned in my previous note I use a low temperature silver
solder to fabricate rubber front ends. It is far stronger than standard
low temperature solders and after testing this weekend I can attest
that it will solder stainless steel. I stripped the nylon off the stainless
fishing line I use and soldered it to a stainless bicycle spoke without
any problem. The material comes in a tube with its' own flux and I
believe the cost was around $10 for 1 oz. package. It Is:
DYNA-GRIP Solder kit no 430 Mfg. by All-State welding products.
(Purchased at a local welding supply house) ---Ken---

King re-Kalculated
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Dear Roger,

Following my last email, I have done some more work on the effects of
Aspect Ratio on both F1G and F1B. I have revised the detrimental effect
of lower Re Nos, in particular between Re = 20,000 and Re = 25,000.
Running the new program for Opt AR has shown a rather steep decline of
performance with AR for both F1G and F1B and in the light of recent info, I
have altered the equations for airfoil efficiency vs Re No. To bring the
results more in line with the latest thinking from practical experience.

Note that the general trend is still very similar regarding the highest
'sensible' AR, but it does take account of the fact that AR's as high as
14/1 for F1G and 24/1 for F1B are still very efficient. However, It still
shows that there is very little gain in performance above 10/1 for Coupe
and 18/1 for Wake. Notice also that the results for Coupe do not take
account of any likely increase in model weight with the higher AR's. I
ran the calcs through the glide sim only and, as the graph showed a slight
degree of scatter, I smoothed out the curve and got the results listed
below, which I believe are now very close to reality.

The other really useful result of all this is that I now have far more
confidence in the data I use for the effects of Re No on the airfoil
parameters. It just shows how much progress can be made in improving the
computer modeling, with only a small amount of good feed back from others !!!

I was going to send this info to Dick Wood but thought it might be of
more general interest so I have, again burdened SCAT readers with yet more
ramblings ;-))



AR 6/1 8/1 10/1 12/1 14/1 16/1
Dur (sec.) 152 167 174 175 172 162


AR 10/1 12/1 14/1 16/1 18/1 20/1 22/1 24/1 26/1
Dur (sec) 306 325 338 347 353 356 356 352 340

Peter King

Re: Wire for F1A
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I have been following the thread about the search for wire for F1A, but now
I am getting confused.
I think the initial enquiry was for a bunt line,,,

But the discussion seems to be developing along the line of using the stuff
to tow / launch the gliders with,
Is this correct ??
Is this the way to get a good bunt ??.

David Ackery
New Zealand

Re: the other Americas Cup
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OK, Lee started this so just for the record, the Americas Cup (the oldest
international sporting trophy in the world) is currently held by New
Zealand, so NZ is the defender not the challenger.
It is an international yatching trophy for match racing

For the right to challenge NZ for this trophy 11 syndicates from Spain,
France, Switzerland, Australia, Italy and five syndicates from the USA have
been slugging it out over two months on the Hauraki gulf through more than
200 races. The winner of the challenger series was the $100M Italian Prada
syndicate that won the best of 9 race final beating out the last American
team, America One.
Now they have gained the privilege of being allowed to race the best, Team
New Zealand, and perhaps win the trophy, (no way Jose !).
Racing starts in about 10 days, stay tuned.

David Ackery
New Zealand

Ike [and Max] Hype

Seen at a local collecto yesterday, Saturday was Henning Nuygen,
who had already arrived for the Iscaason Winter Classic and
the Maxmen. Also seen takeing the last chance to relax was Randy Weiler.
Randy will host his friend Victor Stamov and that is hard work. Those
professional sportsmen work hard and its hard to keep up with them, even
off the field. Also see at said collecto was SCAT scribe and collecto
champion Tom Laird. Tom was giving the new SCAT 40th T-shirt
it's first outing.... nothing personal but couldn't we have
found a more shapely model.

I was trimming out at Taft on Sunday, saw a few other locals getting
in some last minute trimming. It was 70 degress F [that's about 21 in FAI
speak] under a sky with only a few white clouds. Main problem as I see
we have not had quite enough rain to make all the new grass grow.

Roger Morrell