SEN-484 October 9 2000
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News and Reports 2000 - second half
SCAT Electronic News 9 October 2000 issye 484
Table of Contents
=================
Livotto Flash
F1A Attempts - Bauer
Re: High Winds in Aussi Team Selection? - Blakam
old AMA Rules pertaining to A-1 Glider. - Stalick
Re: F1B duration / P. King - Blackam
F1B Simulation - King
The Bats can't Thrash in October - Kamla
A-1 - Thorklidsen
A-1 Rules - Simpson
WC 2001 - Zulic
Tango 400 -huh ?
Livotto Flash
=============
Contest blown out Saturday. All events flown Sunday in a Bluebird day.
Only first places ..
F1A - Brian van Nest
F1B - John Sessums
F1C - Kenny Happerset
F1H - Ernesto Businelli
F1G - Jack Emery
F1J - Bob Gutai, the Alien
In F1B [what else counts !] John Sessums won the 9 minute flyoff
over Blake Jensen. John's model just hung forever in the red sky as the
sun was setting, a very beautiful sight, it's what all this is about.
F1G winner Jack Emery has been elected to the Luddites by virtue
of his sterling fly off performance.
F1A Attempts
============
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F1A Attempts
I'm sitting here at home on Saturday while lots of my friends are on
the field at Lost Hills at Livoto's…. Oh well, such is the demands of
life sometimes. Hopefully I'll be back soon. For now, I want to
comment on a topic which is hopefully not forbidden.
I spoke with Victor Stamov this week and got some details on his
system straight from the "open model box source". I would like to
explain in plain simple english exactly what happened on his unusual
flight at the European championships so that there will be no more
confusion or speculation. His model was preset to perform a "bunt
bail out" maneuver in the event the model was not launched within 3
seconds of the hook unlatching. During a normal flight the model is
launched about 2 seconds after unlatch, but on this flight Victor
encountered some thermal and wind conditions which caused him to hold
the model on the line an extra second to get it straight before the
launch. He launched the model at high speed intending to make a
flight, but unfortunately the 3 seconds had expired causing the model
to perform the alternate flight pattern of: dive down, pull up, wait
a few seconds for the model to slow down, then DT. Victor would
rather the model have bunted normally and made a good flight, but he
had to take an attempt and wait until later in the round to make a
re-flight. So the "bunt bail out" backfired on Victor and happened
when it was not supposed to.
I think many of the witnesses to the flight were confused because the
model was launched at high speed and then did a bail out maneuver.
Most electronic timers have a 5 to 7 second wait before the bunt is
aborted, in which case the flyer slows down the model before releasing
it. Therefore, many stated that the bail out was "impossible" on
Victor’s flight because it looked like a normal high speed launch,
which indeed it was intended to be. However, everything makes sense
when one stops to understand Victor's timer, and of course there was
no radio involved.
The purpose of the "bail out" function is to allow the model to make a
sub 20 second flight for an attempt in the event something goes wrong
while towing. I'd like to point out that glider flyers have been
using the attempt rule for the last 25 years that I've been around the
sport. The most common problem that happens while towing is for the
hook to become unlatched too early. In this case the tower tries to
keep the glider on the line while getting it as low to the ground as
possible before releasing it. He then tries to catch the model to
terminate the flight before 20 seconds. Other strategies include
towing the model into the ground or running straight ahead and out of
sight of the timekeeper in which case an attempt is declared. Our
good friend Bob Isaacson used to coach flyers in training by purposely
unlatching their towhook before the flight, thus forcing the flyer to
figure out how to get the model on the ground for an attempt. More
recently flyers have programmed electronic timers to quickly DT the
model when the hook unlatched but a normal launch didn’t happen – the
purpose of course to get the model to the ground in less than 20
seconds. Victor recognized that it might take almost 20 seconds for a
model to DT from towline height, so he simple set the timer to cause
the model to dive lower, pullout, then DT.
All of this is entirely within the rules of the sport as long as the
20 second rule is in effect. While an F1A glider is being towed, it
responds to the input of the flier by means of the towline. The
rudder moves, the stab moves, the wing wiggler may move, all according
to how the towhook is pulled around by the flier. The model has a
pilot at this stage - it is not free flight yet. At the moment of
launch the glider takes on a flight course determined by all the
previous input the flyer has given to the model including speed,
angle, timer settings, etc., and from that point on the flight is
entirely on its own with only preset timer changes happening. If the
timer settings happen to change 1 second before the model is released
due to input from the flier, that is fine because the model isn't free
yet.
As Roger indicated, this is not a feedback control system at all. The
model is not smart in any way - it only does what the flyer has told
it to do before the launch just like any other timer operated model.
Of course feedback control systems have been outlawed now, so we don’t
have to worry about this. This is unfortunate however, as in my
opinion it would be a great source of entertainment to watch people
actually try to make them work with all the crazy flights that may
result. It is absolutely as Roger stated - much harder than you
think. Imagine if someone worked real hard to make a sensor that
would make the airplane turn the right direction. In my estimate you
might be able to have it make the right decision 9 times out of 10
with years of development. But what about the one time it makes the
wrong decision? Would you fly that model in a contest? Actually, now
that I think about it, the best way to keep the technical / electronic
people from winning contests might be to encourage more electronic
development. They will spend years working out bugs in contests while
the others win. Does anybody have a Windows computer that has never
crashed? Think about the billions of dollars Bill Gates has spent and
the bug list just get bigger.... Time to fly hand launch glider.
Ken Bauer
[Ken - I decided that I would publish your message inspite of saying
that this matter is closed. I will also comment that as expected
there has been much discussion at club meetings and on the field.
It has lead to a jokes about slapping one's thigh along with some
expletive. From observations at this weekend's Livotto that does not
work!
It is apparant that in issues like this people have already made their
mind up so a long discussion is generally not profitable. However Ken
does bring out an interesting point about when the model is free flight
and when the change top the timer program is made. In addition I was
personally interested to learn that Victor had not intended it happen
that way, so confirms my suspicion that this technique is boderline useful.]
Re: High Winds in Aussi Team Selection?
========================================
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>
>While reformatting the Australian Team Selection scores in SEN 482, I
>noticed that the first six scores in F1A, first four in F1B, and the first
>three in F1C were higher by 200 seconds. Must have been something the wind
>added. Be sure Lindy looks out for this in the US Team Selection next
>week.
>I have corrected the Aussi scores for the Luddite readership.
What are you talking about? The scores add up correctly as far as I can
see.
Richard Blackam
old AMA Rules pertaining to A-1 Glider.
========================================
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I have some old AMA rules books, and looked up the A-1 glider specs in the
1959-1960 AMA rules book. It says:
"9.2 A-1 Specifications.
Maximum surface area (ST): 279 square inches.
Minimum total weight: 5.08 ounces
For general characteristics and flight rules, refer to the World Championship
Nordic A-2 Regulations further on."
I think that provides the answer to the question. If not, let me know.
Bob Stalick, NFFS Prez
Re: F1B duration / P. King
==========================
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>Jean Wantzenreither wrote:
>Let's suppose now that both competitors each have a run optimized for
>their own style of flight. The small one of 14 must climb quickly,
>say in 35 seconds, and it is able to climb higher than the large one
>of 20, say 8 meters higher. Of course, the large one will keep the
>final advantage in pure duration. On the one hand because of its
>longer run. In addition because of its better glide. How to take
>account of these
>characteristics in a simulation?
If the large AR model climbs less (presumably because of higher drag) why
would one assume it glides better (presumably the higher drag is still
applicable).
In my experience of 3 high AR models (ca 20-23) in comparison with
several low AR models (ca 14-16), the low AR models climb better in both
initial burst and in the cruise, AND they glide better. The result was
shown in many early morning tests (2 models launched virtually
simultaneosly) that the low AR models always had significantly higher
climb and better duration...
Perhaps the disparity of my results with the theory has to do with the
ability to trim the models optimally in real air conditions. I often felt
that I could not get the best glide from the high AR models despite
trying many, many different trim configurations and tailplanes (some
according to M. Wantzenreither's own articles).
Or perhaps the losses according to Reynolds number are much higher than
anticipated...
Richard Blackam
F1B Simulation
===============
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DEAR JEAN. (re F1B sims).
Dear Jean,
thanks for your interesting and most valuable comments based on real
flight experiments. This is so vital to any attempt to make a computer
simulation. It is, as you intimate, strange that a high AR model should
climb at a slower speed. This is the opposite of what I would have expected.
However if, as you say, the phenomena was noticeable in tests, we must try
to understand why. I will try to think through the possible reasons for
the slower speed of flight with the higher AR. One would expect that the
most efficient result with a high AR would be to use a slightly less cambered
section, for reasons of lower Re Nos involved. However, this would lead to
flight at a slightly lesser CL but with much less drag. (both Induced and
maybe even profile). Even if the camber is the same, one would expect the
best CL/CD would be at a slightly lower CL. This would theoretically
increase the speed of the model slightly due to the lower CL, as the speed is
related directly to the CL. Do you have any thoughts on what may be
causing the noticed opposite effect in practice? I rather suspect there are
some, hard to model, dynamic effects involved here.
Another thought is this:
If the model is a fast climbing, short run type, the higher general angle of
climb would lead to a lower CL (eg Zero at 90 degs). This may well produce
a lower flying speed because the climb is driven more by the thrust than the
lift. (ie the model is hanging on the prop to a greater extent). The climb
rate may stiil be higher though, of course. However, even this scenario
tends to show the opposite effect to the one you describe. (ie the higher AR
model flew slower than the low AR one) ????
It is quite a mystery !!
Very best wishes to you Jean and thank you for your generous comments.
We all, I am sure, wait expectantly for further thoughts and observations
from you and thank you for all the wonderful work and insight that you have
shared with us over the years.
Yours sincerely
Peter King
The Bats can't Thrash in October
================================
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Dear Roger:
Would you please put this information on SCAT.
The Strat-O-Bats "Autumn Thrash" contest has been cancelled. It will be
rescheduled at an undetermined later date. This contest is listed as NC
contest # 52 at Harts Lake, WA. It was scheduled for Oct. 14th and 15th.
I will e-mail you the rescheduled dates as soon as the Army notifies us
of what alternate dates are available.
John Kamla Contest Director
( 206 ) 325-2721
A-1
===
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Thanks a lot Reid digging up that information for confirmation of the
original rules being total area (wing & stab) of 279 sq in. and the weight
being 5.08 oz. I am glad that my memory is still intact as I am aging.
The top Kick was a great flying model and you did quite well with them as I
recall. It seems like all of the sig contest wood was good back then and I
remember that I had to also add weight to my original A-1 to meet the 5.08
oz rule. A-1 was a great event especially for the kids back then.
Incidently we allow proxy towing at our San Valeer nostalgia contest for the
older members that just can't muster the leg power to do it.
Thermals,
Terry Thorkildsen
A-1 Rules
=========
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Terry, I do have a copy of the rules as they were in 1959 when the TopKick
design originated, and your belief that the allowed area was the total
projected wing and stab areas combined is correct. The rules then as now for
the international events is a combined projected area.
The rule book I am quoting from is a 1962 Official AMA Model Aircraft
Regulations. And no, I am not a pack rat who would have kept something like
that. But a great friend of mine, the late Bob Westall from San Antonio, did
have a copy of the rules and when his wife called me and asked if I would
like his model magazine collection, I gratefully accepted and this book was
on top of the stack that she and his sons collected out of his workshop. Bob
was on the Air Force team with me from 1959 thru 1963.
On page 13 The A-1 specifications were given.
Maximum surface area (ST): 279 square inches
Minimum total weight: 5.08 ounces.
For general characteristics and flight rules, refer to the World
Championship Nordic Regulations further on. (meaning in this book)
Then on page 46:
"TECHNICAL REGULATIONS FOR FAI FREE FLIGHT COMPETITION
3.2 GENERAL CHARACTERISTICS
The dimensions of the models are limited to:
3.2.1 Surface area
The surface area (ST) includes the total surface of the wing or wings and
that of the horizontal or oblique stabilising surface or surfaces.
The surfaces taken for calculation are the orthogonal projections on to a
horizontal plane of the surfaces in question with the model in the
horizontal
flight attitude.
As for the weight being 5.08. Yes that was the old weight requirement and
that weight is forever burned in my mind since the original TopKicks were
designed to be built with good Sig contest balsa and would be built at 3.75
to 4.0 oz. and would require a lead slug to be carried as ballast. Of course
that was prior to DT timers and we all used a fuse. The weights of the
TopKick from the Jetco kits was more in the 6.0 to 6.5 oz area when built
with kit wood. But they still flew very well. I can still remember the late
Mark Valarius winning the 1965 Nats at Philly with one that weighted in at
6.5+.
Of note, I'm glad to see you still fly straight tow A-1 in some of your
southern Cal. contests. And I really get a kick out of seeing a TopKick
placing in the top 3 if not winning. Do I still have TopKicks?, yes and I
flew them at Seguin in the H1 events until 1998 when I had a knee replaced.
And that ended my glider towing days.
Hope this info helps. Reid Simpson
WC 2001
=======
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I am interested for date of World championship in Lost Hills. I need this
date for reason adaptation our date for World cup competition
(Oct 2001)
Best regards, D.Zulic from Slovenia
[ I do not think it has been announced yet. I assume that it will
be early October. I also assume the Sierra Cup will be on
the same weekend as now.]
Tango 400
=========
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Hi, I have the assembly instructions for this Tango 400, Electric assisted
Thermal Glider and is says: "Please refer to the aeromodel.com web site for
detail pictures of the radio gear installation". And I cannot find it on
your web site. Any suggestions.
Thank you, This email address is being protected from spambots. You need JavaScript enabled to view it.
[ I'm sorry I do not know what you are referring to .. I have never
heard of the Tango 400, or seen reference here?]
........................
Roger Morrell
