SEN 734 - 2 Sep 2002
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SCAT Electronic News 2 September 2002 issue 734
Table of Contents
=================
SEN
Poitou 2 minutes - Chaussebourg et al
As Dukie figures it - Dukie
Extended Max - Boutillier
CIAM Nullification - Editor
Curved wingtips - Segrave
Re: broken H.L.G wings - Magill
.7854 - Brokenspar
Model Aviation Free flight Column - Joyner
AREA OF A CURVED SURFICE. - Wilkinson
SEN
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As Dukie figures it
===================
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OK
This should help the mathematicians figure out the area of an elipse. L x W x
.7854 = area. Example: a 6 in. chord by 24 in. span stab. 6 x 24 =144 X .7854
= 113.0976 sq. in.
There are more complicated formulae out there, but they still all come up
with the same answer as this one.
While we're at it you can get displacement by: boreXboreX.7854x strokeXno. of
cylinders=disp. It is so fast you won't believe it.
Dukie
Poitou 2 minutes
================
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F1G
42 have flown
1- ZERI NED 750
2- CHAPMAN GBR 676
3- CHALLIS GBR 669
4- MILLET FRA 632
5- BOUCHET FRA 627
F1H
20 have flown
1- WILLIAMS GBR 656
2- DUJARDIN FRA 596
3- CHAUSSEBOURG FRA 587
4- ECHIVARD FRA 579
5- CHABOT D. FRA 571
6- COOPER GBR 557
F1J
6 have flown
1- HARRIS GBR 769
2- BAYLEY J. GBR 718
3- WATSON GBR 686
The "supermax" was used in the early first round in order to avoid long
Fly-Off in the afternoon in windy weather with strong thermals.
A "fair play award" should have been awarded to John COOPER GBR who
complained, after the end of the contest when looking at the score
board, because he had been given a "max" at the third round, and he had
flown only 77 seconds. John insisted for the score board to be rectified
and obtained the 6th place instead of the 2d one. John, you are a
Gentleman.
Many Thanks to Louis DUPUIS and the "Vol Libre Moncontourois" for
organizing this very good contest.
Extended Max
============
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In th last issue of SEN appeared the results of 2002 Poitou and French
Nats. The extended max was flown on the seventh round after a rather
late start in the morning (9 A.M.) in order to have less thermal
conditions in the last and decisive flight. I believe that this system was
already used in at least one of the World Cup events in Hungary
or Slovakia.
We found many advantages in this way of doing:
- Not necessary to hurry in the morning.
- The contest organiser is relieved from the burden of a big Fly-Off,
as in the current rule.
- For the contestant the interest is maintened from the first to the last
flight, i.e the contest is not finished after the first flight.
-One has already seen contestants having slightly dropped the first
extended flight, then lacking motivation and giving up before the end
of the contest.
We should avoid this which could lead in long term to a decreasing
number of flyers.
-It is more logical to have the flight duration increasing during the day.
Any comments?
Bernard Boutillier
CIAM Nullification
==================
At the recent Poitou event and I undestand on of the Hungarian events , the
super max was pushed to the last round. At Poitou the reason was 'to make the
contest more interesting' , i.e. as the result would not be determined on the
first round. Of course the result is not determined just by the first round,
thinking that is the best way not to be in the flyoff. The problem [other than
it is not in the spirit of letter of the rules] that I see is that it changes
the long round from a performance round to a thermal round. At the Poitou
contest the last round was flown in breezy condition and there was a long
retrival. I helped one other visiting sportsman who would not
have made it back for the flyoff if I had not gone
to fetch him in my car. I was also suprised that this person flew last on
his pole inspite of being clean, the other sportsmen insisted on
maintaining the flying
order eventhough they had no chance of making the flyoff. At this contest
it was perfect conditions at the 'normal' start time of 7:30 and even at the
more leisurely actual start time of 9 am a 5 minute flight would
have an equally leisurely retrival. In F1B everyone that was clean at the
end of round 6 made the 5 minutes so it did not change
the number of people in the flyoff [what did was the dead calm,
dead air in the 3 rd and 4th rounds].
I noted that the next morning when they flew the F1B flyoff, neither
made 5 minutes. In talking with Anselmo he flew a back up model
as his #1 was damaged the previous night .. and he tweeked
the rudder under power cause the model to fall off to the left not getting
his true climb.
I noted that many people on the last flight set their d/t to 3 minutes
and my time keeper asked me if I wanted 3 minutes or 5. While
retriving my model I realized that I had made a mistake in saying
3 minutes. This is because that time would be used as a tie breaker.
I did not have a desire to do a long chase and was well out
of the money but I should have told my time keeper 5 minutes eventhough
my d/t was set to 3.
The advantage of flying to the FAI rules is that they are clear and
any local exception has to be clearly called out. This way of
interpreting the rules is clearly not in the spirit of the intent.
Local interpretations always lead to confusion, in particular
with visiting sportsman who may have difficulties communicating
with the organizer. If people think the rules is bad, go
back to the CIAM, ... and tell your delegate to think next time
before they make a change.
The joke going around part of the flying field was that the
reason the super max was sent to the last round was because certain
F1C flyers of the hosting nation [Bernard's name was not mentioned]
did not think they could make 5 minutes in the morning.
Curved wingtips
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After working out the area horizontally annd span wise of the curved tip.
block it up at the dihedral angle and measure the hoorizontal span of the
projected tip. For the projected area, simply multiply the area by the
relation: projected span/flat span. Only one measurement is required thus
eliminating errors due to multiple tries.
Mike S
Re: broken H.L.G wings
======================
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I had the same problem with breaking H.L.G wings, however I used to fly
quite a small glider, a contest proven New Zealand design with wings made
from 3/16 balsa, and they flew great up to about 3/4 power, but when I threw
them hard they did all sorts of strange things like barrel rolls, and never
went the same way twice on the way up. I figured the solution was to build
larger models, and built a number of Lee Hines's Sweepette 20 design, and
these flew much more consistantly and I could throw them as hard as I liked.
To stop the wings from folding, I started using around 7lb straight
grained wood about 1 1\2 inches wide on the leading edge of the wing, and 5
lb or lighter quater grain for the rest, that seemed to work, and with care,
the models still ended up weighing around 38 grams including timer. I think
sometimes there is a tendancy for very light quarter grain wood to be
extremely short in the grain, and ends up very brittle and can snap like a
carrot.
Well, thats my two cents!
thermals to all,
Jason Magill
New Zealand
.7854
======
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The area of an elipse, or a paraobla,
is easly computed.
Lenght by width by...for an elipse: .7854
( I remember that one. )...
for a parabola, it's .84.. something.
Look it up in your Marks.
The parabola is kind of fat.
When you start curving the wing tips,
you need a bath tub !
( I'm thinking of a Greek of old, who got in the tub,
and somehow solved a long standing riddle of science.
I always admired the method...)
Can't you see Charlie Sotich*, filling a tub,
climbing in, catching the overflow in a little cup,
looking at his notes, bending over his gram scale.....
Now, who in hell is building eliptical plan form
wings with curved dihedral ?
Brokenspar
* or Dave Linstrum
Model Aviation Free flight Column
=================================
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Roger:
Just got a letter from Bob Hunt, Aeromodeling Editor at Model Aviation
stating that:
"After some rather extinsive study, it has been decided to reapportion the
amount of column space given to each modeling subject in relation to the
number of AMA participants involved or interested in that particular
discipline. This has been determined by a study of membership subscription
records where interst area is indicated."
Beginning with the January 2003 issue, the Duration column will be limited
to two pages and will appear four times a year (January, March, June, and
September).
Louis Joyner
AREA OF A CURVED SURFICE.
=========================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
RODGER.
WHAT EVER HAPPEND TO THE OLD ATTAGE OF MULTYPLYING THE
CORD BY THE SPAN THAN MULTYPLYING THAT BY .7854?
THX DON.
[Don - and others
Please type your submissions in mixed case - in Internet etiquette
all UPPER CASE is considered shouting - something only done
while your Nelson is running.]
..................
Roger Morrell
