SEN 856 - 25 Feb 2004
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SCAT Electronic news 25 February 2004 issue 856
Table of Contents
=================
Low Tech Trimming - Barker
F1E ? - Brokenspar
Dhlg - Murphy
F1A Stuff
FFDLG - Rivers
The King Lurks encore
Banned or Spammed - was - : Did you receive this ? - Zeri
Dwindling contribution to technical development
Fin position - Salzer
plastic hooks live - Robbins
SEN and SPAM
Low Tech Trimming
=================
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A belated reply to John White in SEN853
John I do not think that you have gone wrong. It is always good to try
things. I think we all grew up finding out, probably unconsciously, that
balancing one thing against another made for safer flying. We probably
first learnt right rudder balanced against wash in on the starboard wing to
give the usual right/right pattern. Then there was left rudder balanced
against right sidethrust to give a safe right/left pattern. The discussion
of these matters has been legitimised since Peter King talked to Alex
Andriukov . Alex pointed out that he had several 'cross' trims and
that the important thing was that, if the airplane went off pattern, that
there should be a tendency to return to the pattern. Leaving aside any
theory, John, what matters is, does your right rudder/left sidethrust do
that?
Something somewhat related to this might amuse you. A few years ago I was
persuaded to build one of those atrocious things called a Keil Kraft
'Achilles' which has a freewheeling prop. All freewheeling props tend to
turn the aeroplane to the right on the glide. On the 'Achilles' the effect
is so bad that left rudder is needed to stop a right spiral. Under power
the left rudder causes the thing to cavort all over the sky. This can be
cured by adding right sidethrust. The trouble is that the sidethrust
increases the right turn on the glide - back where I started. After wasting
a lot of time trying to balance side thrust and rudder I tried the
unthinkable - I trimmed the beast to go left on the climb. Result, a
smooth, fast climb. Then I gave the aeroplane away.
What does this tell us? Well, two things I think. First, unusual trims will
suit some aeroplanes. Second, if an aeroplane is difficult to trim there is
usually something wrong with it so why waste your time - build something
else. Some people can walk on tightropes; it is clever and amusing but not
a very practical way of getting about.
Regards
John Barker - England
F1E ?
===
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We didn't hear much about F1E, apparently held the week before
the Maxmen at Lost Hills.
Are those man made hills high enough to make it interesting ?
Brokenspar
[There was a report a few issues back and the answer to the last question
is yes.............]
Dhlg
====
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Hi Lee,
First let me say I hope your knee repair goes well and you will be back
to full speed soon.
Last year I was in Japan on a business trip and I attended a YSF contest
with my friend Yasuo Yoshioka.
At this meet I saw people flying very traditional looking HLGs with a
discus launch technique.
One flyer was a small man in his 70's and he was able to obtain launch
altitudes with this launch that was on a par with the best of the
traditional flyers back home. I looked at his model and there were no
moving parts, no peg on the LH wing tip, nothing out of the ordinary.
The only thing slightly different was the larger than normal sub rudder.
I wish I could have taken a video of his launch, but that wasn't
available to me.
The model was launched from the LH wing tip in a slight ( < 20degrees)
nose up attitude. It climbed in a LH spiral which opened up to a RH
glide.
Murph
F1A Stuff
=========
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
I have a lot of useless (for me) F1-A related items: Tow-Reels; Timers, etc
etc. Anyone interested? Please specify your needs.
Santiago Rodriguez. This email address is being protected from spambots. You need JavaScript enabled to view it.
FFDLG
=====
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Hi,
I'd like to jump into the mix with my own report about plans for a DLG.
My son and I are working on one right now, so please keep your reports
coming, i.e., those who are building and flying your own. We hope to fly
this model in AMA HLG contests starting in May.
Our model will be about 60" span and is for discus launch. We often see
Mark Drela flying here at the local R/C site so we hope to get some tips
from him about the discus technique. The model will have 2 servos (stab
and rudder) and an electronic timer. That part is already done and is
functionally proven. The rest is airframe build. We are using some
fuselage parts from a Vasi F1H glider, but adding built-up wing and stab
with thin flat bottom airfoils.
Hopefully, all this ice and snow will leave soon and flying can start.
Dick
The King Lurks encore
=====================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Peter King
pj2king This email address is being protected from spambots. You need JavaScript enabled to view it.
I forget now who started all this, but he sure has stirred things up re the
Lurkers !!
Great to suddenly see so much fascinating stuff and so much more real
technical debate. I must admit there have been times when I have found very l
ittle
in SEN to grab my attention, but a lot of this is, unfortunately, because I
am unable to get over to the US to fly in any of the constantly advertised
competitions and get very depressed, reading about the lates comp dates. I do
however always enjoy checking the fly off times in the results as it helps me in
trying to pin down base line performance when working on simulations. ;-))
What ever happens, please don't talk any more about stopping SEN !! The
latest issues prove how many interesting lurkers there are out there and how much
SEN is needed !!
Great stuff, Keep it up guys !! Can't wait for the next one !!!
Ardent regular lurker and occasional contributor.
Peter King
Banned or Spammed - was - : Did you receive this ?
===================================================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Dear Mr Scat,
on February 17th I sent you the comment here under.
I noticed that it was not published, and I didn't care.
In the last scat-news I read that only in exceptional cases articles were
not published, so I started wandering why I could have such an honor.
I send it again, not because I insist it should be published, but just in
case it went lost for whatever reason.
I appreciate a lot your good work.
No more trips to Holland ?
Best regards,
Anselmo
[Anselmo
You are not in the same category as the infamous Brokenspar or even
Skykieng ... or whoever it was that I really did not publish on purpose.
I get a lot junk mail as you can imagine and can only assume that your
previous e-mail got thrown out with the trash, in error !!
I think you cover a very interesting subject, that you and Allard
are uniquely qualified to talk about - that of interlectual property..
No I have not managed a business trip to Holland for a while - after
all it is winter !! and my trips have to coincide with a
World Cup contest !!
By the way if anyone thinks that their item was over looked please
don't hesitate to send it again and even mention for SEN
in the subject line ... ]
Dwindling contribution to technical development
===============================================
Anselmo
Hello everybody,
the analysis of Allard about what's going on in our little world gives me
the occasion to add a grain of personal view.
In the past (this past runs well before SCAT news) I was very active in
publishing articles and drawings of my models on magazines in different
parts of the then civilized world.
At a certain moment the revolution of the change of the BOM rule arrived.
The virus spread itself on the whole community, reaching also the low
lands where I live.
It was quickly clear that one could buy perfect "standard" models or have
models built according to given specifications.
At that moment I decided that nobody would ever be able to have a model
built by somebody else including whatever part, design or detail
developped by me (this in the improbable case that one could even desire
to have a model incorporating some of the above mentioned items).
This did automatically exclude any publication of whatever drawing or
development I was busy with.
Attention: this didn't prevent me from giving my airfoils or complete
drawings to some modellers of the "old" type, who did privately ask me.
Copies of my model or some of my airfoils were used by modellers, even to
be national champions or to win prestigious world cup contests, the only
thing I asked to them has been: don't publish it, and don't tell anybody
that this is my stuff, if you are asked, it's your stuff.
Now I think I'm slowly coming to an ideal situation: the number of people
interested in what I do is probably close to zero, so I can slowly come
back to the open world, when time allows it.
Our friend Andre Schandel (Vol Libre) was so kind to appoint me as "King
of Poitou" in 2002, after my 8th victory of the free flight days there,
and then again "Emperor" in 2003, after the 9th victory, so he deserves
the drawings he asked me many times.
Given my slow pace building new models (the newest is the model I used to
get third in Israel, built in the winter 1998/1999) and the reticence I
can have in giving away things I didn't have the time to try in advance, I
think that all the work in airfoil development and other areas will have
to wait some time before it will be published.
If I can't wish to many of the readers: happy building, let me at least
say: happy flying !!!
Kind regards,
Anselmo Zeri
Director 1257
European Patent Office
Joint Cluster Human Necessities
DG1-TH-R 09-11 MB
Tel. : (+31)-70-3403147
Fax: (+31)-70-3403980
e-mail : This email address is being protected from spambots. You need JavaScript enabled to view it.
[ While the availability of commerical models has made it possible for
many more people to continue to particpate and to achieve excellent
performances I still believe that the good flyer who builds his own modlels
has that chance to do just that little bit better - Anselmo, is a good
example of that.
I'm sympathic to his position because of my involvement
with electronic timers. While I'm prerpared to talk about them and
share ideas and thoughts I'm not
will to share the actual source code of the software. This has taken many more
hours to develope than I can ever re-coupe and I would not be happy
about someone selling something that incorparated my code with out appropriate
acknowledgement and compensation. ]
Fin position
============
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Top fin - bottom fin - front fin - rear fin - T-tail all have aerodynamic
and mechanical properties, and probably are more often selected for
mechanical than aerodynamic reasons!
My personal experience & solutions:
Top fin in front of the stab is prone to get nicked by the stab in a crash
(classic mount allowing the stab to pop off). So put it far away ... only
possible on long fuselages as in F1B's. No good for towline.
Rear fin avoids nicking, gives a clean rear end, but long fuselage for a
given moment arm. Good towing. I used them for F1A.
Low fin must have LE sloping at least 45°, otherwise will hang up too often
and break fuselage. Will also bear high stress on circling landings (even
DT?). Aerodynamically clean, good towing, good place to put & protect bunt
or VIT mechanics. Used it on F1E, because they do not circle (mostly), and
land occasionally in trees on wooden slopes (Hans Gremmer called this shape
"D-treeing") where the sloped LE will lead to less hang-ups.
T-tail not "in" any more. Aerodynamically clean and good place for
mechanics, but in a crash the stab exerts a strong bending moment which
often breaks off the boom right in front of the tail - reenforcements weigh
much. Used in old F1A's, but not any more.
You miss any mention of size? And shape?
I would love to have good calcs for all of them. Mostly I use the "looks
good - will fly good" rule, start a bit too large and cut back if it seems
preferable. Furthermore my fin sizes may fit my box fuselages, but may be
wrong for thin tubes ...
A further fin puzzle: I had a glider with a Jedelsky type wing (external
ribs, you know). The same glider with normal built-up wing would not fly
worth a damn until I added lots of _frontal_ area.
There remains a lot to be studied ... and tried ...
Klaus W. Salzer
plastic hooks live
==================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Herb Robbins does have a dozen or so of the Czech plastic
tow hooks
that Jim bradley referred to in issue 855/ @$15 ea.
This email address is being protected from spambots. You need JavaScript enabled to view it. 408 356 8659
SEN and SPAM
============
All of us are getting more SPAM, unsolicited e-mail and to counteract this
people are putting place measure to automatically detect this kind of e-mail.
For those of you who get SEN e-mailed to you, sometimes it will get stopped by
this process. The example below is because a particular organization had put
the word scat on their list of forbidden words.
Another example is a SEN edition that was rejected by a readers mail police
because I had put Halloween edition on the subject line The word Halloween was a
forbidden word at the French aerospace company.
In addition we use some old software in the preparation of SEN, not all
components conform to the latest most rigorous e-mail standards. We are looking
at upgrading part but for the time being some more reader's mail providers may
not accept SEN. For this reason we always have it on the web site so you can go
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Subject : This is an alert from eSafe
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.......................
Roger Morrell
