SCAT Electronic News December 7 1999
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SCAT Electronic News December 7 1999
"SCAT - 40 Years of FAI Free Flight Competition"
Table of Contents
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Yagi Apologies to all - Kowal
Struckling - Brokenspar
FAI and F1B performance - Linkosalo
FAI records - Kaynes
Yagi Apologies to all
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When I sent my original documents on the Yagi antenna I did not
think about the problem with MS-Word format. The nice thing was it allowed
me to put the text and drawing together in one package. I do this all the
time with engineers I work with and have little problem. In the future I will
put all the text in a text only file and the drawing in BMP format. I converted
the CAD drawing to BMP so "everyone" could read it. These are the only
tools I have to generate documents so hopefully if you need the info and
cannot read it someone can convert it for you. Good Luck ---Ken---
Struckling
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Fellow strucklers -
You may think, at first, that the word is some
quaint example of free-translation
from the Danish. Not so. It comes from that
philosophical curmudgeon, Kierkegaard,
for whom the word speaks of unsuccessful
transactions with the opposite gender.
It is apt as discribing our travail with the
motive power for the F1B class of model.
In the days when the class was called Wakefield,
1954 to 66 for me, my first love was to struckle.
The accelerated entropy of the quality of Pierelli
in those days caused a lot of struckling,
until finally I was struck, totally. Thus the interest
in the FAI power model, where you can
buy RPM's without fear of dissapiontment ( given the
right propeller ), and obtain
the pleasure Korsgaard seeks: "..the thrills are the first few seconds...".
Now, I am struckling all over again,
with the P30 ! ( my grandsons ). ' Designing ' a P30
has difficult constraints, - 30 inches by 30 inches, 40 grams,
and 10 grams of rubber to struckle with......
All for a few seconds of thrills.
Brokenspar
FAI and F1B performance
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Roger,
the discussion on reducing the performance of FAI models seems to have
started again. For this, I have two suggestions, the first of which is for
f1B, the other could be applied to all classes. As basis, I'd like to say
that I do not like the idea of reducing rubber amount to extremeties. I
see that this would make the class harder for beginners, as the difference
between average and experienced rubber handling ability will be more
significant the smaller is the amount of rubber in the model. My first
suggestion is:
1) Ban the variable pitch prop for F1B
It has been claimed that VP will bring additional 10 to 20 meters of climb
height, that will translate into 30 to 60 seconds of additional glide
time. Moreover, the VP hubs are expensive, and there are only a handful of
people in the world the build (and sell) such equipment. Although I'm not
in general in favour of banning gadgets, I take a different opinion in VP.
2) Lifting surfaces must have an airfoil, that is not concave at any
position.
The discussion on F1B performance has mostly concentrated on how much more
energy the new rubber releases. I think most realistic figures come from
indoor community, that claim up to 10% more power compared to Pirelli. Yet
the flight times without lift have increased from 4+ to 7+ minutes. There
must be something else than just the rubber. Also F1A:s fly up to 5
minutes now, when 20 years ago it was a sign of a good model, if it made 3
minutes without assistance. No better rubber there.
So what is the difference then. I claim that a good deal of the better
performance comes from improved aerodynamics. We have now higher aspect
ratios. as well as much thinner profiles than 20 years ago. To really cut
the model performance we need models that do not glide as well as the
current ones do. I do not believe that limits in the wing span, or
materials would work too efficiently here, as well performing models tend
to be rather compact in size. However. moving into flat bottomed airfoils
would mean much thicker and less efficient airfoils, that would cut the
glide time considerably (compare e.g. some P-30's that can be built with
either flat-bottomed or concave airfoil). Sucha rule would require
building new wings, but would enable the use of the same fuselages, thus
the current models could be modified to the new rule. The rule could be
also easily checked, with a simple ruler.
-Tapio-
FAI records
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The current records are confusingly called F1A F1B F1C for models which are
effectively open models. - very loose restrictions.
The records section of the Sporting Code will be updated but only to be
effective from January 2001. As I understand the current status of the
changes which have been passed these will give the following options, most
notably adding records for flying in competitions which should have more
relevance to most FAI flyers:
Current record special models in glider, rubber and power classes:
duration
distance in a straight line
height
speed
F1A, F1B, F1C duration in competition
Indoor the new records will be:
Special record models: duration under ceiling categories I to IV
F1D specification models: duration under ceiling categories I to IV
F1L (FAI EZB) models: duration under ceiling categories I to IV
F1N (indoor HLG) models: duration under ceiling categories I to IV
Duration in competition for F1D and F1L, subdivided into:
best single flight
best 2 flights
best total of 6 flights
Ian
.....................
Roger Morrell
