SEN 878 - 13 Jun 2004
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- Category: Archive 2004
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SCAT Electronic News 13 June 2004 issue 878
Table of Contents
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Moscow Wings for sale - Parker
lightning - OssiK
AM Cup So Far - Parker
F1B Propellors - Blackam
Re: Propellors - Wantzenriether
Thanks
Moscow Wings for sale
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Please post on SEN;
For Sale, New Moscow built F1A wings. I damaged these new wings while they
were in route to some Israeli modelers. I bought them and repaired them. No
visible or structural damage. Two ship sets available, one ready to cover (light
white primer coat on C.F. and one set covered with Coverite CoverLite
(symmetrical color pattern, from center: yellow, blue and red tips).
Airfoil very
similar to M&K long, uses 4th generation spar construction, ribs are multi-
laminate, use standard 2 x 5.5 mm dia wing wires. Center Cord 6.1 in, dihedral
cord 5.1 in and tip cord 3.6 in. Mid span 55.9 in, average span 89.8 in.
: 460.5 sq in. Dihedral: center flat, tips 4.7 inch. Warps, center flat,
Tips .15 washout (both). Weight: covered set 214 grs, uncovered 186 gr total.
Price: 150$ for the uncovered set, 175$ for the covered set. Wing wires
available but extra at 10$ set. I do have one set of bent wires that would
increase the tip dihedral to 6.3 inches-15$. Shipping cost not included. Can be
pick up at a Lost Hill contest or NATs with prior arrangement.
Email for any other info, I can send EXCEL spread sheet showing MAC,
recommended stab area, tail moment arm etc.
Jim Parker
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lightning
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Dear Friends
I was very sorry when I heard the tragedy at the British Nationals to Peter
Harris. We miss him.
And I was quite shocked when remembering what happened at Maniaco ECh's -96.
It was a practice day. A big thunderstorm came over the field. I collected
my models and went to my camping car at the edge of the field, close to the
trees along the road, but not too close.
When the heavy rain started my team fellows were still on the field. I drove
there to pick up some of them.
I stopped the car 20 meters from the fellows. Opened the door. I was just
sliding down from the seat, right hand was on the door handle, left one on
the car body, right foot still on the floor, left one middle way down to the
ground. And then lightning hit the car aerial! Broke it. Continued down to
the ground along the floating wet car side about one meter behind me.
It make two tracks (like ski tracks) some 5 cm wide, 1 - 2 cm deep and 10 -
20 meters long towards Jari Valo who was on the field putting his models to
the box. We were cowered by a big dust cloud from the field; it was not
smoke, luckily.
Jari had heavy feelings on his feet. He looked his shoes, if they got fire
or something? But he was OK.
So were I and the other fellows around. No human injuries.
But the car had some defects: The aerial was hanging along the side of the
car, most of the copper sock over the class fibre rod had evaporated of,
some brass parts of the connector to the car body had exploded. Paint had
burned of from many places of the top. There were three openings in the
self-made extension roof, which I had to tape or seal to make it waterproof
again.
The over voltage protector box in the voltage cable to the radio had
exploded in pieces. The radio did not work. But no other electrical
problems, I wondered very much!
I reconnected the voltage cable without any electronics. And I was very
surprised, when the tape recorder run and I could hear some voice from the
other speaker. Not normal loud but some 1/10 of normal volume!
At home I opened the radio. There were some connecting plates exploded in
pieces.
Inside the car, close to the aerial connector I had a model box made of
aramid honeycomb. The plastic covering on the nearest corner was melt and
got black. Inside the box, at the opposite corner, where the lightning went
off or tried out, there was burned paint. But the models were almost OK.
Only one rudder had come off.
And now I wonder: If I did not drive the car to the field, did lightning hit
some of my fellows like it hit Peter now???
Or what, if the lightning had hit less than one second later, when my hands
were still on the car body and foot/feet on the ground?
Ossi Kilpelainen
AM Cup So Far
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Subject : SEN
Text Missing ffrom the last issue.
Here's the latest results. It's hard to believe we're one-third though the
season! I may have missed the Eastern USFF Champs results. I'll get them in
on the next installment.
This is the time of the year were we look at the scores and determine if we
should "make a run" for the first place trophies. Tom Coussens started off
strong in F1A with 2, 30 points=A0 wins but will have to leave Lost Hills. F1B
is still anyone's ball game. Gil Morris has 2, 25 point contest wins at lower
attendance contests -- perhaps he is planning on larger attendance at the NATs
and maybe an endless October on the West Coast. Jack Emery is looking very good
with 3 high bonus point wins-- as I know from last year, getting that fourth
win can be tough! Brian Van Nest is looking hard to beat with a total score of
107. That was enough for the 2003 winner Mike McKeever but Martyn Cowely won
with 108 points in 2002-- you never know. Dave Shirely is on top in F1J with 2
wins.=A0 I'm putting my money on Cody Secor-, 2 F1P wins with no other
competitors in sight! We will be giving a provisional trophy and certificate(s)
for F1P this year.
Reminder of the 2004 rule change for official entry: 4 flights in F1ABC and 3
Flights F1GHJP must be flown to be an official entry. This impacts the bonus
points. Of the 60 events flown to date, there has been 7 situations were a
single sportsman had started but did not fly the minimum rounds needed and so
the winners received one less bonus point. Please be aware of this rule and
remind others of this during the America's Cup contest. SCAT will re-look at
this rule before the start of the 2005 season. Also, CDs please use DNF for
rounds
that a flyer "did not fly" and a 0 (zero) for when a flyer flew but received no
flight time, i.e., double engine overrun, two tow-in's with line attached etc.
The NFFS web site will be updated in the next few days for those who prefer
to review the results in the native Excel format. While at the NFFs web site,
check out the new FAI forum-- I posted some information on towlines.
As usual, send any corrections to my email.
Thermals,
Jim Parker
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F1B Propellors
===============
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Re: Propellors
Larrabee's propeller design works poorly on typical F1B's for 2 reasons:
1. it's optimised for low loading (as he stated) and an F1B prop is
often highly loaded. This is the primary problem.
2. the typical high A/R blade results in low chord widths which create
two problems of their own:
2a. the local Reynold's number is very low with the usual problems
2b. the long narrow chords make it very difficult to accurately control
the blade angles during manufacture.
How do I know? Come and have a look at the reams of calculations and
dozens of test-flown designs!! I feel guilty for all the decimated pine
forests for which I am responsible!
Propeller design is a very esoteric thing. Good results are often
attained by the 'wrong' methods. Alex used blade element theory to
design the world's current best propeller at a time when blade element
analysis was pooh-poohed as 'passee' and 'wrong'!
regards
Richard Blackam
Re: Propellors
===============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
----- Original Message -----
> Propellors --- Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
> Just to get a feel for the subject has anybody done any in depth studies
on the best blade shape for either 26 or 24 strands. <<
Please take a look at :
http://perso.wanadoo.fr/ff.specials/page5.html
Is this what you have in your mind, John ? Larrabee's program concerns props
without variable pitch, but perhaps it would be possible to simulate the
variation by taking some points, each of them defined by model velocity and
torque. I'm not equipped for that... My Gfa-BASIC prog needs for each R/10
station : chord (mm), f/c (relative mean camber), t/c (relative max
thickness), pitch (in mm or degree) and of course diameter.
As you write... we will see.
Jean Wantzenriether from VL and FFQ.
Thanks
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To Jack Emery for his donation is support of SEN
.....
Roger Morrell
