SCAT Electronic News June 13 1999
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- Category: Archive 1999
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SCAT Electronic News June 13 1999
Table of Contents
==================
Aspect ratios - King
Sad News on Mile Square - Hines
News from FAI Model Supply
Sublime to the Ridiculous - or is it the other way around - Andresen
Hebrew Language Signs for Model Boxes - Dilly and semi-gorilla
Noodles [or Not] in Bishop
Aspect Ratio
============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Dear Roger
I was very interested in the piece about aspect ratio in the last SCAT page.
I have done quite a lot of theoretical work on AR over the years and have
some data that I have quite a lot of confidence in as, what ever method I
use, I get roughly similar results. The thing about it is, even if you
forget the effects of reynolds number, you get a plateau at AR's close to
those in regular use. Even the theoretical benefits of going higher are so
small that I doubt the returns are worth all the problems of stability,
construction, weight etc.
For the record, here is a summary of some of those results.......(with
correction for RE effects).
Note 1. The absolute durations are open to debate but the comparisons are,
I believe, valid.
Note. 2. I have, to some extent, tuned the following results to fit with
what we see on the flying field, but the figures for "sensible" maximum AR
do not change significantly from a completely theoretical analysis, leaving
out the effects of Re No.
F1A
AR 14/1 18/1 24/1 28/1
DUR. (secs) 242 256 263 262
Highest AR worth using, above which gains are minute. ca 20/1
Improvement from lowest to opt AR 8.7% (NB the highest of the classes)
F1B
AR 12/1 16/1 18/1 20/1
DUR. (secs) 346 360 362 361
Highest AR worth using, above which gains are minute. ca 18/1
Improvement from lowest to opt AR 4.6%
F1C
AR 14/1 18/1 22/1 26/1
DUR. (secs) 375 384 387 385
Highest AR worth using, above which gains are minute. ca 20/1
Improvement from lowest to opt AR 3.2%
There are a few notes worth mentioning, as follows;
1. Any use of higher AR's would depend on developing new airfoils that have
much better properties at the lower RE Nos. I think this is going to be very
difficult to achieve without much better and more wide ranging testing
procedures.
2. There could be a use for slightly higher AR in F1C in the area of Flapped
wing sections. This is due to the probable higher glide CL that could be
achieved, producing a higher level of induced drag which would, in turn,
highten the effective advantages of the higher AR.
3. The higher the AR used, the more important is optimising the planform and
span wise camber and thickness distribution.
4. I guess the relevent fact about all this is that limiting the span of
models is not going to make much difference when it comes to reducing
perfformance unless we cut it drastically. eg. AR = ca 10/1 or less.
To me that would simply lead to some very ugly looking models. We might as
well take up Vintage and be done with it !!!
Having said that, it looks like reducing the AR of F1A to say 14/1 might have
an effect but that is not the class that produces the biggest problems of
long fly off flights!!!
I hope this is of value, if only to promote more debate on the subject. I
have, by the way, a large collection of info, graphs etc, on EXEL spread
sheets. If anyone is interested in seeing more about the methods, graphs and
data used, I would be happy to send them over the net.
Peter King
Mile Square
==========
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Good Morning Roger;
In this morning's O.C. Register, Metro section,
page 1, is the notice that
Judge Eileen Moore has ruled that demolition and construction of the
central triangle area may
begin "as soon as demolition permits are issued, possibly by Tuesday".
In other words, regardless of the lawsuit pending, she denied to hold
construction until after the
trial, which seems to me to shut down access to the Mile Square flying
site from this time and probably forever more.
As one who has flown there beginning in 1954, I will miss the
convenience of having a chance to
go fly locally and see buddies, without making an all day trip to do so.
Ah well--- onward to somewhere.
Lee Hines
PS; Guess you can delete Mi SQ from the weather site listings, eh?
News from FAI MODEL SUPPLY:
===========================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Dear Roger
Kindly inform others that FAI MODEL SUPPLY:
A . New area code is 570 i.e. 1-570 882-9873
B. we are in the process of acquiring STARLINE PRODUCTS , SAL will still sell
POLYSPAN.
C. We now have May rubber which many tell us is outstanding( " no noodles " )
Thanks
John
[ see also last article]
Sublime to the Ridiculous - or is it the other way around
F1C and F1D
============
As to the F1C noise situation, it appears to be a non-problem in search of a
CIAM solution. Well hope they do a better job than on
F1D, which is basically PennyPlane with rubber restriction.
Keep up the good work,
This email address is being protected from spambots. You need JavaScript enabled to view it.
Hebrew Language Signs for Model Boxes
=====================================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Roger,
In case any teams going to Israel are interested, Diane Stringer,
the wife of one of our F1B flyers, has arranged translations into Hebrew of
the following signs, which, as UK team manager, I have used on many past
occasions when taking model boxes by air (though not previously in
Hebrew...).
NOT TO BE PLACED ON ANY BAGGAGE CONVEYOR
HAND CARRY ONLY
HIGHLY FRAGILE
DO NOT SHAKE OR JAR
THIS SIDE UP
PLEASE HANDLE CAREFULLY
If anyone is interested in copies, a couple of International reply coupons
to me at: 20, Links Road, West Wickham, Kent BR4 0QW, UK will have them
winging their way to you. I copy them onto bright orange paper and stick
them all over the UK team boxes (along with English versions), and, apart
from a disastrous encounter with the semi-trained gorillas used as baggage
handlers at Heathrow last year, they've usually helped.
Martin
Noodles [or Not] in Bishop
==========================
This weekend we had our SCAT summer part in the Bishop CA area
and in addition the feasting and other social activities did spend
a litle time flying at Brian Van Nest's test site. Of great interest
was the first flights with the May 99 rubber that John Clapp mentions
above.
Before commenting on the outcome of the tests I would like to make
a comment as applies this OR ANY OTHER MATERIAL published here.
None of this is a recommendation or endorsement of the procduct
by the editor or the SCAT Club. The opinions stated are always
the personal opinion of the writer. .. and you need to use
your personal judgement on what you think about that writer.
Given all that I can confirm that what the possibly prejudiced John
Clapp says .. the May 99 rubber is very good. Rumour again has
it as best ever energy test results. As I said once before the
test is how it performs in contest conditions, particularily in Israel.
.........
Roger Morrell
