SEN-448 August 1 2000
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News and Reports 2000 - second half
SCAT Electronic News 1 August 2000 issue 448
Table of Contents
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Questions about Wobbekiong etc. - King
just a few questions. [ from Cuba] - Suen
re Reynolds Number Effects/Aspect Ratio - Andressen
Latest from the Gummi Bears**
FAI WORLD CHAMPS 2001 - MomFox2
Questions about Wobbekiong etc.
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
I have often wondered what exactly is the theory behind the current
generation of 'full size' aerobatic wing airfoils. Can anyone tell me.
>From what I have seen they tend to have very large nose radius and a straight
line shape from a very forward point of Max thickness. to the TE. Similar to
the Woebbeking section but with a completely symmetrical shape, (zero
canber), for obvious reasons, ie inverted flight etc. In the light of H's
(??) remarks about some findings of increased lift slope with round nose and
forward camber, could this be the reason they are used? If so I guess it
would increase the 'responsiveness' of the wing in some way. This brings me
to another question. Is the reason tied in with the use of flaps and
ailerons on an aerobatic plane?
I find the whole area more and more confusing now because I understood the
main effect of the Wobbeking TP section was to reduce the lift slope ???
Peter King
just a few questions.
======================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Hello:
My name is Omitsa Suen, the purpose of my message is because my father
belonged to the national team in our native country, Cuba. He participated
for 15 years in championships all around the world. He feels he was born for
this, but the dreams have been put on a pause since the government decided to
shut it down over there. This happenned a few years ago, after that he became
very sad and all he has done is dream of going back to the competitions. The
problem here is that he feels very dissapointed since we have not been able
to find any associations in our town
(Tampa, FL). I feel that you can help me with these few questions that I
have, and they are:
1.- Where can we find a flight field close to our town?
2.- What hobby shop do you know of that can provide us with the materials
required to build a model, since we have not found a store with all of
the neccesary ones.
3.- What are the now a day rules for the tournaments?, since my father
was told that the first flight's time was going to be changed to a 4
minute duration, Is this official?.
I really hope that you can help me make his dreams come true, because I know
that he deserves this and is really good at it. His name is Eugenio Suen, in
case that you wish to look in the records. Please, contact me as soon as
possible about this.
Sincerely,
Thank you
Omitsa Suen.
[There is a major Freeflight site at Palm Bay in Florida.
Look onthe SCAT Web site www.aeromodel.com/scat for Frree flight suppliers
The rules are on the SCAT site and at the FAI www.fai.org.
In addition hopefully a modeller who is local to you will contavt you.]
re Reynolds Number Effects/Aspect Ratio
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
This was pretty well covered for F1C in SYMPO 96.
Basic conclusions included both RN & AR:
1. Low AR doesn't benefit from high CL (lift coefficient).
2. Low CL takes away advantage of high AR.
3. Max benefit with high AR & CL.
4. Best way to get CL is with single surface ~10% drooped TE.
5. Aerodynamically Jedelsky section almost as good as single surface.
6. Constant chord good aerodynamically, but taper helps structure.
Hoerner shows effect of planform on induced drag.
Microscopic gain from 5deg sweepback.
Major gain from curved tip dihedral.
Closest is Don Thompson's Soarcerer 1n Zaic 1964-65 YB.
Great claims are made for various tip configurations on the www.
Grid-Wing is similar to Gremmer Bird Feather tips in SYMPO 88.
Kroo is C-shaped winglet that points back at fuselage.
Spiroid is more extreme & forms a closed loop.
These may be found with your favorite search engine.
IMO ellipse is not ideal for models. I never had a HLG that didn't
glide better with 1" lopped off of a rounded tip.
IMO major limitation in F1C is structure to get high CL with high AR.
Any dropoff in time with RN is well beyond 10' span IF high CL is used.
These do not apply to unlimited classes like AMA, F1J, F1G etc.
Good luck,
H
Latest from the Gummi Bears**
===========================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Thanks for your e-mail.
John or Sally will respond as soon as the USFF Nationals are over
( 7/29/00 thru 8/4/00 ). Please note that our rubber factory has
informed us that a significant price increase is being
formulated. Next rubber shipment is due in approximately 8/11/00.
Regards
John
** My applogies, John, just could not resist the multi-language
pun.
FAI WORLD CHAMPS 2001
=====================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Hello,
I was wondering if you could help me find out who is in charge of setting up
for the World Cup 2001 in Lost Hills, California? I helped with the one that
was here in 1993 in regard to hotel accommodations, supplies for the field,
etc. I would love to be a part of this upcoming event, but do not know who
to contact. Please let me know ASAP. I would very much appreciate it.
Thank you.
Carolyn Fox (aka: This email address is being protected from spambots. You need JavaScript enabled to view it.)
[ The 2001 World Champs will be held in the fall of 2001 (probably October)
at Lost Hills. The offical organizer is the AMA. Seeing I'm not the AMA
this information is not offical. The person who is the most
likely to the the Contest Director is George Batiuk [This email address is being protected from spambots. You need JavaScript enabled to view it.]. George
is the team manager for the US Junior Team that is about to leave as we speak
for the Junior World Champs in the Czech Republic. George is also the CD
for the US Team Selection Finals to be held at Lost Hills, 10-14 October 2000.
In fact George is also looking for helpers for this this event, in partcular
timekeepers.
I know that George will be looking for helpers for the World Champs. At ]
this time he just wants to collect the names of those who
will be timerkeepers. I expect that
he will soon be looking for people to help out in other roles.]
.....................
Roger Morrell
