SEN 903 - 14 Sep 2004
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SCAT Electronic news 14 September 2004 issue 903
Table of Contents
==================
FAI European Aeromodelling Championship F1E - Chaussebourg
Crossflow - Bogie
For builders - Ackery
magic palm question
planform..and multi dihedral - Skykieng
Wing planform - Salzer
Classic Towline glider rules - Kruse
Classic Towline - Edmonson
Classic glider in the National Cup - Campbell
Stuck for Stickers
Classic Glider - Andresen
Contest Invitations & results - Augustus
Fw: [ciam-info-l] Winners - FAI European Aeromodelling Championship F1E
=========================================================================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Dear Roger,
Here is the message from FAI concerning F1E European Champs results.
You can find complete results on FAI web site mentioned in the results.
Best regards,
Pierre
----- Original Message -----
From: "FAI - Christine Rousson"
To: ; "CIAM, Information"
Sent: Wednesday, September 15, 2004 8:24 AM
Subject: [ciam-info-l] Winners - FAI European Aeromodelling Championship F1E
>
> Sport: Aeromodelling
> Title: FAI European Aeromodelling Championship F1E
> Type : Continental
> Date: 08.09 - 13.09.2004
> Location: Rana near Louny (Czech Republic)
>
>
> Final Results
>
> F1E Senior - Overall
> 1st: Daniel PETCU ROM
> 2nd: Kurt BLEUER SUI
> 3rd: Pierre CHAUSSEBOURG FRA
>
> F1E Senior - Team
> 1st: Czech Republic
> 2nd: France
> 3rd: Italy
>
> F1E Junior - Overall
> 1st: Martin HORN CZE
> 2nd: Daniel BILDEA ROM
> 3rd: Cristian FAUR ROM
>
> F1E Junior - Team
> 1st: Poland
> 2nd: Romania
> 3rd: Germany
>
> The full results can be found at the following address :
>
http://www.fai.org:81/aeromodelling/competitions/free_flight/ch04/EC04E.HTM
> and
>
http://www.fai.org:81/aeromodelling/competitions/free_flight/ch04/JEC04E.HTM
>
> FAI congratulates the Winners and thanks the Organisers of the
> Championship.
>
> ____________________________________________________________
>
Crossflow
=========
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This is something to avoid because it tends to increase the drag on the
model. In the glide mode crossflow occurs when the fuselage is at an
angle of attack to the direction of the surrounding airflow. Visualize it
as a particle of air starting at the bottom centerline of the fuselage at
the nose and the fuselage is angled perhaps 6 degrees to the local airflow.
The particle has to go around the fuselage whether its cross section is round
or square. Since a fuselage at angle of attack produces very little lift,
the drag is increased not a little. On square or rectangular fuselages there
is a little lift but the air going around the two corners tends to
separate from the body causing larger drag.
Wind Tunnels have been used from the days of the Wright brothers. In every
case of testing to this day, the drag from wind tunnel tests turns out to
be less than that found in full scale flight testing. The reason is that the
wind tunnels operate at great noise vibrating the air which tends to reduce
the drag of the models being tested. I have often thought that perhaps I
could reduce the drag on models by producing a vibration. It would be legal
as long as the source of the vibration generator were produced by airflow
turning an unbalanced "water wheel" mounted on top of the wing outer panel.
That idea came from vibration testing of the Lockheed C-5A in flight. The
purpose of the flight was to generate a desired range of vibration to test
the structural strength of the ship. The Lockheed S-3A used a vibrating
wing of small size sticking out of the side of the fuselage behind the wing.
Here it could be run at various vibrations to simulate a range of frequency.
Nice for our models but not legal.
I think the best we can do for cross flow is to attach a streamer to the
side of the fuselage near the wing mount and watch how the streamer lines
up with the fuselage centerline. Then we can get an idea for setting the
wing mount to minimize the crossflow.
On many plans we see varying angles between the wing and the fuselage. Frank
Zaic has told us that the glide angle is around 6 degrees for optimizing the
glide. That could be a starting setting. Glide testing with the
streamer could fine tune it.
For builders
=============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
For those who prefer to build, rather than buy,
this is worth a look.
www.emachineshop.com
cheers
David Ackery
[ but Dave if one was a TRUE builder
one would do one's own machining.
and I guess the true Luddition would not use a machine
at all .. not even a Fat Cat ?
]
magic palm question
===================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Roger:
I will be getting a new Palm Pilot as a back up.
I've quickly seen some new models I think some have the capabilit of loading
and replaying mp3 files and showing
jpg's. Tungsten ??
Anyhow. Is there something I should know or be careful with regarding
compatibility ?
Thank you
Ernesto
[Ernesto
The PP must support the "universal connector" i.e.
a serial port.
and you must user either the super magic PP program or
version 3.16 or later of my software
roger]
planform..and multi dihedral
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Jean makes some interesting observations below.
Some thoughts.
A crossways airflow path across a dihedral joint during a sideslip
outlines a very strange airfoil...one with a very pronounced reflexed
trailing edge.
Dear Hardy Brodersen brought this to my attention years ago as
justification for his using elliptical dihedral.
Whatever, I would like to bring attention to a normally overlooked
advantage in using multi-dihedral breaks.
Let us look for a moment at a geometric phenomena applying to the outer
tips in a six dihedral break power wing.
Assuming no washout or washin along the span, the angle of attack on the
airfoil at the zero lift angle (as found in vertical climb) is
identical. However, in the glide ...say at 6 degrees alpha, the outer
tips --because of the dihedral angulation -- will be at a lesser angle
of attack than in the inner panels. ( If this is hard to grasp, think of
the tip raised to a 90 degree "winglet". At 90 degrees dihedral there
is no apparent change in the winglets angle of attack no matter what
changes occur in the center panel.)
What the above discussion discloses is that the higher angled tips act
in the glide as though they have washout....which is good! This is a
very desirable feature for a power ship because it eliminates the need
for generating washout through twisting the wing. It is very good for
speed in the climb because when washout is put into a wing it increases
the drag in the climb (since that washout needs to be accommodated
across the whole wing in the trim)
Perhaps reader's may recall in the past --with more flexible wings --
seeing a power ship flatten out its dihedral during the climb...evidence
that all is not aligned rightly across the span. To produce negative
lift with a cambered airfoil means flying it at a very high-drag
producing angle of attack.
Hmm. It suddenly occurs to me that virtually no competitive F1C flyers
design the airplanes they fly anymore. Oh, well....
billious g
Re: planform
============
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> Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
> To clarify Manuel's comments below, I had mentioned in SCAT that there
was evidence that for low Re a rectangular planform with tips tapered
for
the final 20% had some advantages. Somewhat the same observation is to
found
in Martin Simon's book on Model Aerodynamics. <<
What when the wing is no longer straight to the incoming air...? I don't
imagine a wing is working as in the books, as soon there isn't a dead
calm
morning. And certainly not in a circle-climbing motor ship. Then what
becomes the "elliptical" loading ? And the dihedralled tip airflow when
the
model is facing a quarter-roll in a gust ? Lou Young started a study
about
that in the Sympo 1975, Wing shaping for improved efficiency. As a
rubber
flyer I love to have a tip leading edge which allows as high lift as
possible in strong sideslip situations, that is a rounded edge with
positive
swept. Never a sharp corner... I would like to read some opinions about
this
item... Amiti=E9s. JW
Wing planform
==============
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I think I do fly a maybe "test case" to the planform discussion: my F1B
"WELLES" has always had a simple rectangular wing, not even the 20% tapered
tips mentioned. Just 1.5m of 110mm wing. Reason mainly that it was supposed
to be a beginners plane.
Two special properties however:
a) tips are not cut square, but LE shorter than TE by about 30mm (straight
cut) referring to WW1 Fokker ideas (I believe) that the front of the tip
does not generate much lift
b) the tip is turned up (mostly my own idea) - next to last bay normal
airfoil, tip rib straight underside tangential to the front part of the
airfoil, TE a sharp break straight to this end (about 10mm high from
building board).
As flown very often together with other planes in competitions it shows
nearly the same glide performance as most others, in the same air my times
are very similar to the rest, even if I do not get quite as high. This may
show that for the higher speed in the climb the advantage lies with the
tapered wings, while in the slower glide other factors prevail.
It would be interesting to do a real comparative test with planes having
only this difference in wing design, but otherwise identical fuselages,
props, etc. (I fly balsa box fuselages, and home made simple prop units)
Who has enough time for this project?
Klaus W. Salzer
Classic Towline glider rules
==============================
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In regard to Mr. Mattes' request for feedback about the classic towline
glider event: I agree with the comments that were published by Mr.
Buddenbohm, and Mr. Hines on the subject in the September 12, 2004 issue
of the SCAT Electronic News.
Thank you,
Matthew R. Kruse
AMA 39126
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Classic Towline
================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Hi Bob Mattes
A few notes on Classic Towline:
1. A combined classic towline event (A/1 and A/2, and anything else that
meets AMA overall size limitations)
2. No weight restrictions
3. Combine with HLG and CLG for National Cup Points.
4. No circle tow or bunt mechanisms or any other mechanisms with the
exception of a 2 position auto rudder. Moveable tow hooks must be locked
down, fixed hooks encouraged. (This and line length are the only
processing requirements)
5. One minute maximum time on tow. Note: This is supposed to be a
simple event for timer and flyers.
6. No builder of the model rule. Old models built by anybody encouraged,
along with new models with any degree of modification to meet rules.
7. Standard 50 meter line length to FAI rules concerning pull and flag.
8. 3 flights of 3 minute max unless conditions do not warrant it. No
rounds.
9. Flyoffs for perfect scores: to be coordinated by contest director at
specified time window. Contest director may opt for unlimited flight time
or provide each contestant with a reduced length tow line ( 25 meters).
Are you coming up to the MMAC September 25-26 NFFS exempt meet in North
Branch? We could use some competition up here.
Best regards
Dave Edmonson
Secretary MMAC
Classic glider in the National Cup
==================================
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Hello Bob: I am in favor of adding both the glider events to the National cup.
these events will round out the catagory and will choose a real glider
champion.
Now: About the rules.
1.) The large glider catagory has a three minute max. this should be two minute
s at catagory three contests. The NOFFA club has had an open towline event for
years. In the last five years, most with good weather, only two maxouts have
recorded. The National cup will bring more activity, with a posibility of
more maxouts. it will not be a big problem.
2.) About that 15 second tow maximum: It was my impression that this rediculous
rule was established to hinder the possible track stars out there. The only
time you need to be a track star is when you tow into a downer on a relativly
decent day. The trouble with this rule is that on many of the sites in this
country, if one is a relativly fast runner, he is going to run out of real
estate in a hurry. That being said, if a day is somewhat breezy and one tows
up into poor air, the skill in keeping the model on the line should be
rewarded. After all,
the event is called TOWLINE glider. My understanding is that the idea behind
these events is to go back in time and fly like we used to.
3.) The builder of the model rule; The builder of the model rule should be kept
, in order to keep these events in line with all of the other national cup
events. the other events reward building skill. If the BOM is done away with,
then all of the other events will be in line. Even as a kit manufacturer, I
feel that the builder of the model rule should go away.
4.) I fly these events on a regular basis. I would hope that anybody else makin
g comments about these matters would identify their activity level. I personaly
do not care to have rules decided by people whom I would call "outsiders"
Thank you
Lee Campbell
P.O. Box 3104
Muncie, IN 47307
1-765-289-7753
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Stuck for Stickers
===================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Hello,
Where can i find the fai stickers??
Yours Bram
http://www.aeromodel.com/TM/E34766T330
Classic Glider
==============
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Bob,
Classic Glider is an interesting concept and could be popular if done right.
To me, nothing says classic towline like a Jasco Floater. I agree with
Stan/Lee that 1 event, minimum restrictions is likely to provide more
interest by including models like the Floater for the "balsa flies better"
crowd who endorse the BOM rule. Lack of weight restrictions also reduces
athletic requirements.
Don't recall any Classic Gliders in Zaic's "Model Glider Design" even having
AutoRudder much less circle tow. With a fixed, open (no latch) hook there
is little concern that someone would circle tow. See no need to outlaw AR
either.
Unless it is very windy when it would be necessary to throw line to save
plane (a CD call) it seems like the tow restrictions could be:
Keep posession of line=official
Throw line=attempt
Throw reel=zero
Like the 3X3 format w/40sec attempt.
Thems my opinions.
Good luck on a good event,
H
Contest Invitations & results
=============================
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Roger,
Your work on SEN is groundbreaking, unique, splendid and vastly appreciated.
Please do not construe the following remarks as a reflection on your
selflessness , skill or dedication to free flight.
If I may offer a suggestion - printing complete contest announcements, replete
with events, directions to site, and hotels is unnecessary and tiresome. A mere
reference to a web site would suffice for the handful of us who actually
intend to attend an event on the other side of the continent, or ocean.
In the same vein, reporting of contest results to the 87th place, I believe, is
equally uninteresting to the majority of us. I await a flood of remonstrations
to my opinion, and lacking that, my request is that you delete or edit said
contributions.
BA
................................
Roger Morrell
