SEN 754 - 10 Nov 2002

SCAT Electronic News 10 November 2002 issue 754

Table of Contents

Fly Powered Planes - Lipori
Rubber Apocalypse - Booth
Mike Segrave's Taper Wing Neutral Point - Barker
F1B/TAN II, a newcomers view - Bradley
Tan II and Sports Tan - Wiley
The solution to the rubber problem! - MAC the Bigot
Plans - Smiley
How much rubber - Stanbridge
Re: Fly Planes - Gregorie
FF joke - Meyer
F1C & J vs United Airlines - Nyhegn

Fly Powered Planes
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.


We all sniff too much glue and dope but it hasn't affected your memory yet.
We are however, giving away our age by remembering.
The article was I think in Model Airplane News sometime in the fifties.
Anyway this web-site has some information the care and feeding on fly
engines. They even have fly power kits for sale.

Bob lipori
Have fun:

Rubber Apocalypse
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.


In the last week or so I have read of the great apocalypse
in the world of F1B and other rubber powered free flight
events. The demise of Tan II has sent many sportsmen into
a chicken-little, end-of-the-world frenzy that seems to
have reached near panic proportions. I am not sure which
is more astonishing, the depth of the despair or how
quickly some of us jumped off the deep end. We have
already proposed rule changes to correct the inequities,
suggested possible handicapping for the ”have-nots” and
discussed the logistics that CD’s will need to follow to
manage a set of dual rules needed to bring fairness back to
the contest field. We have decided to dye this inferior
rubber so it can easily be identified. We have
contemplated the potential energy in bicycle tubes, bungee
cords, fuel tubing, underwear elastic, newspaper bands and
the relative value of lubed vs. unlubed condoms. Few
materials even remotely rubber or better yet latex have
escaped our curiosity. We have established the near
impossible task a beginner would face becoming competitive
and finally, have forecast the ultimate demise of our
events! E-Bay suddenly has pounds of Tan II on the block.
My head has been spinning with visions of models slowly
cruising to the ground with the prop still turning or
Montreal pins deploying ten seconds after launch. For all
of the wisdom our small fraternity of sportsmen possess,
and I believe we are generally a pretty smart group, I am
more than a little surprised that we worked ourselves into
a state of hysteria without some very basic information.
That information would be actual flight tests.

John Clapp was kind enough to send Bob Piserchio and myself
a box of the current Sport Rubber for just that purpose.
We tied up a handful of motors, passed them out amongst our
Saturday morning group and yesterday (Saturday 11/2/02) we
actually flew with Sport Rubber. The participants were Bob
Piserchio, Roger Morrell, Mike Mulligan, George Schroedter
and myself. All motors were 30 grams, lubed. Bob’s motors
were tied at 28 strands (unknown length); mine were tied at
26 strands and were approximately 14.25 inches long.

We can all take a deep breath and stop looking for tall
places from which to jump. Sport Rubber isn’t THAT bad. I
flew two motors and was able to get about 480-490 turns in
each motor, which is just slightly below what I am getting
on an equivalent 14.25” July 02 motor. I also got 90-92%
of the full-wind torque I am getting on the equivalent
motor. I did not hear from George, but the rest of us saw
only a very slight drop in the initial burst and no
immediate change in model behavior. We each experienced
some hesitation in the mid range cruise, even falling off
to the left a little, except Roger who made a slight rudder
adjustment in anticipation of the lower power. Bob offered
that this rubber seemed to fly better than it tested. We
all agreed, we could pretty easily trim around the problem.

This was not intended to be a carefully monitored
scientific analysis. We simply tied a few motors and flew
them. Our statistical sample was a few motors from one
batch and the flight tests were conducted mainly to try to
collect some basic practical data, a “feel” if you will,
that will give us a base-line from which to initiate future
discussions and the next evolution of rubber strand. July
02 Sport Rubber is definitely not May 99 or August 01 Tan
II, but the consensus of the group was, if not great, that
Sport Rubber was at least adequate. I have some sections
from some vintages of Tan II that are not this good! The
sky is not falling and speculation regarding our demise is

I spoke to John Clapp Saturday evening and with his
permission have the following to pass along. The factory
does have a very clear understanding of what is important
to us. They have set a goal for themselves to improve the
performance of the next batch of rubber a minimum of 5%.
That rubber, to be named “Super Sport” is targeted for
delivery to John in about 60 days. 5% now and a few more
5% improvements in the future and maybe we will all forget
Tan II.

I do not however, think our limited testing should signal
the end of our concern, but I hope it slows the panic.
Again, this is not superior rubber, it does need some
improvement, but it is not so bad that we cannot manage to
get through the next few months without rearranging our
rules and the structure of our competitions. There have
always been “have” and “have-nots” when it comes to rubber
quality and availability. Let us also not forget that
rubber is only one component in a successful contest
program. This IS important, but it is just a dust devil
bouncing across our world, not a class 5 tornado.

Bill Booth

Mike Segrave's Taper Wing Neutral Point
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

In issue 753 Mike asked about a 'moving' Neutral Point. In this context =
I think that Aerodynamic Centre would be more appropriate than NP but =
that is not really important because what is causing the problem here is =
the method of finding the centroid of the wing.

Mike starts off using the standard method as mentioned in many, many =
books, ie. he extends the root and tip chords by the tip and root chords =
respectively and then from the ends of these extension he draws a =
diagonal line. At this point Mike deviates from the usual construction =
and takes a point midway between the intersections of the diagonal line =
with the leading and trailing edges of the wing and uses that as the =
centroid; that is not correct for a tapered wing. What is needed is a =
further line joining the mid points of the root and tip chords. It is =
the intersection of this new line with the diagonal line that gives the =
centroid. Working in this way the figures change as expected when the =
extra wing area is added. If the leading edge of the root chord is =
taken as the origin then the centroid of Mike's basic wing is at 2.695 =
chordwise and 2.682 spanwise from the origin. With the piece added to =
the trailing edge the centroid moves back by 0.028 and inboard by 0.068.

There is another error which is commonly seen when using this =
construction. It is assumed that the chord at the centroid is the mean =
chord but this is not the case and so taking a point midway between the =
leading edge and the center at the centroid does not give 25% of Mean =
Chord. It is necessary to mark the length of the mean chord centrally =
over the centroid chord and then mark the 25% distance on that. The =
amount of this error depends on the amount of taper. To give an idea, =
on Mike's wing the chord at the centroid is 2.292 and the mean chord is =

A further point of interest is that it is often stated that this =
construction gives the center of area of the wing, that is not so, it is =
the centroid.

If you do not want to bother with geometry to obtain the centroid then =
the following equations will do the job:

Let Ct =3D tip chord, Cr =3D root chord, LS =3D leading edge =
sweep(distance of tip LE behind root LE) and SS =3D semi span. Then:

R =3D Ct/Cr
A =3D (1+2R)/(2+R)
B =3D A/(1+A)
X =3D B(2Ct+Cr+LS)-Ct - distance of centroid behind root LE
Y =3D B(SS) - distance of centroid outboard of root LE

I hope that helps. It is difficult to be clear without using sketches.
John Barker - England

F1B/TAN II, a newcomers view
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

As a newcomer to F1B I thought I would share my views and perspective of the
TAN II issue and what my thoughts and plans are.

I have been following all of the recent news on TAN II and find some of the
comments rather amusing. Where is written that F1B must have rubber that
will allow the models to fly over 6 minutes in neutral air? So what if the
models will only do 4 1/2 or 5 minutes with the new rubbers. Within couple
of years most all of the excellent TAN II will have been used up anyhow and
the rest will be rotting in peoples workshop because they are "saving the
good stuff".

The idea of color coding rubber is especially absurd. How do you know what
color the make it in the first place? Rubber, as we all know, varies
greatly. I can see the protest now, "No this is light red rubber, not red
rubber, so I can have an extra 2 grams".

We all should be very grateful to John Clapp for what he is trying to do.
John easily could have said this is what you get, buy it or go someplace else
and not even gone through all of the grief he is going through trying to
develop the TAN Super Sport.

For some reason a few people think we need to handicap rubber. If we need to
handicap rubber why not F1A and F1C also. How about we giving those 50 to 59
years old and extra 5 meters of line and if you are 60 or older you get 10
meters extra. Maybe in F1C we could give the people who want to use G15
Super Tigers, Rossi MK 1's, Cox 15's a 10 second motor run and those using
early Nelsons and later Rossi's a 7 second motor run. These ideas are just
as absurd as trying to come up with a handicap rule for rubber.

Come on guys, let it be. Learn how to be a better air picker and fly better
trimmed models instead of whining "I don't have any good rubber". As for me,
I plan to have a long and, hopefully, successful career in F1B flying with
whatever rubber is available.

Jim Bradley

Tan II and Sports Tan
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

First, to John Clapp: Thanks, man! You have really been working for our
community. I have no doubt you will be working harder in the future to find
the best rubber possible.

Second, Sports Tan. I switched over to this product for Mulvihill and large
rubber stick last summer. It seems a cross between Tan I and Tan II and
works peachy in both classes. I was getting enough turns and torque to fly
well and the rubber was definitely more robust. I have not tried it on F1B,
as the batch I bought from FAI was 3/16". However, based on my experience
(flying not bench testing) it should average about 85-90% of the average
batch of Tan II I am now using (July 02) and it is probably better than some
of the below average batches I have flown with in the past.

Third: As a new guy still trying to struggle into the flyoffs (any flyoffs!)
I am still flying against my own devils, and these usually do not reside in
an extra 10 in oz of torque and 20 more turns. They reside in things like
attention to mechanical systems, thermal picking and launching left one out
of seven times. Thus, I am not concerned that other, more experienced,
fliers have the "better stuff." They paid for it; their willingness to pay
for it shows their commitment to the sport; let them use it. Eventually they
will run out of it. Maybe by that time I will have learned to fly F1B a bit
better than I do now. In the meantime, I think I will save a bit of that Tan
II for the time when my flying skills match the quality of my rubber.

See ya'll at the Autumn Cup in Seguin,

Ed Wiley

The solution to the rubber problem!
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

The demise of rubber as we know it and whining weenies of F1B

As a former F1B flyer who hasn't touched one in 25 years I feel fully
qualified to throw in my two cents worth, now up to five cents with
inflation, and add some fuel and creative solutions to the current
crisis. My first recommendation is that all F1B flyer take a valuim or
strong gin & tonic before they write to SCAT again, it really helps to
sooth the nerves and takes the edge off an already too stretchy
situation. Based on my quick mind and brilliant problem solving I have
come up with a very simple solution to the perceived and over blown
(hah, hah, hah, get the pun, blown, as in blown motor, damn I'm clever)
rubber problem. Remember, we sometimes have to look outside the box for
the really great solutions. Here is a solution that is so creative and
simple that I am awed by my own masterful mind. The answer is hanging
right in front of us at any hardware store. The solution to the problem
is the old tried and true bungy cord. What is really brilliant about
this is that they come in different colors, that takes care of the
color coding issues. You use one of those real long ones for unlimited,
I think they come in red? You use the middle size for F1B, maybe they
are green? and for coupe you use those little teeny tiny bungy cords.
The great thing about them is that they already have hooks on them,
Duuuhhhh, we don't even need to have all those gadgets to hold the
motor in the model, just use the hook on one end of the bungy cord to
hook to your tail boom and use the other hook to wind from. Simplicity
and multiple problem solving all wrapped up in one inexpensive and
readily available product and it covers the gamut of all the rubber
events. In a pinch you can even hook some of them together, no know
tieing! In testing out my idea I have run into a few snags and knots
that need to be worked out. The most pressing one is that the motor
tube has to be a little bigger, I figure a 4" diameter tube should do
the trick and nice thing about it is that you can buy the tubing at any
plumbing store. It's a little on the heavy side but what the heck!
Another issue that came up was the pylon to tube size ratio, it kind of
makes the model look like a pin head! When you break your bungy the
metal hook is a bit of a wild card to you have to be on your toes. I
solved this problem with a clear acrylic prop protector that is six
feet in diameter, no matter what happens the hook will not hit you but
I do have to admit I couldn't fit the winding shield in my model box.
All those problems are course able to be worked around, the one that I
have not been able to solve just yet is how to reconcile the fact that
different bungy cord manufacturers use slightly different size and wire
diameter hooks. My initial solution was to create a chart that the CD
has which shows the variety of possible combinations. For example, in
the early morning round I might use an Ace Hardware brand purple bungy.
For the windy rounds I switch to the Home Depot Keep on Trucking brand
which is really tough and manly. For the fly-offs I have found the
super stretchy girly bungies from the sewing stores to be ideal. They
only come in pink but if you have made the fly-off the color won't
bother you.

There you have it, an all-in-one super simple solution with universal
application and wide availability. Leave it to an F1A flyer to solve
the F1B problems. I like thinking outside the box and in the mean time
I am going to go and crawl back into mine. I'm available for free
problem solving and consulting at any time.

Mac the Bungy Bigot Boy

Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

I run a WW-I plans kit service(actually getting back
into as a guy stole all 700 +-plans)
I enjoy reading scat. SO keep it coming.
I have developed some spoked wheels for the scale FF guys. So far I have a
couple of changes to make,and will have the final stuff maby the end of the
I there is any intrest in LIGHT things, Give me an E-mail,or a
buzz--603-659-3380---Snail mail is
Clarke Smiley
model plans trader
23 Riverbend
Newmarket NH
This email address is being protected from spambots. You need JavaScript enabled to view it.
the "plan man"

How much rubber

Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

Hello people, how are you?
I have a Candy G coupe, a Perky P 30 and a Pygmy 20. These were designed by
Bob White (Perky 30) and Andre Burdov (Candy G and The Pygmy 20).
I'm using 1/8 rubber, How many strands should I use for each of these
I sure would appreciate your response!
Mark Stanbridge
This email address is being protected from spambots. You need JavaScript enabled to view it.

Re: Fly Planes
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

This email address is being protected from spambots. You need JavaScript enabled to view it. wrote:

> Recently I told a few of my neighbors about making fly planes and they
> all told me I sniffed too much glue. We used to glue a tissue
> streamer on a fly for kicks also. I would like some of the "older"
> modelers to think back----where did the article appear, Air Trails or
> Model Airplane News?
I think the article first appeared in Aeromodeller some time in the
mid 1950s. I remember seeing a article in it about fly power being
invented by a bored group of indoor flyers. Apparently they were
stranded in Switzerland due to a missed rail connection while on
their way to a World Champs. They had balsa, glue etc, though no
models and there there were a lot of flies about...

There's a website, , but it doesn't mention the
article I remember seeing.

Martin (another mine of useless information) Gregorie

FF joke
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.

Someone(blame Steve Jensen) suggested I send this here,and it took me a week
to find "here",sorry. Here goes:
A sad-eyed F1b flyer watched his rivals accept their awards,and having
broken or lost all his models by the flyoffs he was very depressed. A tall,
white-haired man with a briefcase walked up to him,smiling. "You could have
used an edge out there today,I suppose. Maybe this would help." Opening the
briefcase, he beckons the FAI guy closer,"In here I have the latest thing in
airfoil templates,good for a 2% reduction in sink rate, at a cost of only 1%
worse climb." "wow!" says the modeler. "And here," the tall man whispers "is
a new material,5% stronger than carbon,and nearly as stiff as boron!" "Gee!"
says the Wakefielder, leaning in close. "And this," the white haired man
holds up a small box-"is Beige III rubber, all that exists in the world, one
pound. It stores 2.4% more energy than the old Pirelli,and is just as
consistent." "Oh my," the flyer says, "I'd love it but it all must be very
expensive!" The tall man's eyes begin to glow,and his voice deepens,"I can
make you this offer because I am The Devil,and the price... is your soul!"
The flyer edges away,crossing his arms, and asks suspiciously,"What's the

I hope this amuses somebody, and I love this site- will explore it more
thoroughly tomorrow. Sad that in three mos. on the net I just run on it now!
Thanks and good flying,
Rich Meyer

F1C & J vs United Airlines
From: "Henning Nyhegn"

Hi Roger.

Subj: No models engines on commercial airplanes in USA:

I want to tell you very shortly about my experience checking in to a
domestic flight with United Airlines from San Francisco to Chicago.
It took one and half hours to check my modelbox because there was my FJ
model with a 1cc motor in it.
After some discussion, two extra security people were called to assist from
UA. They told me that I was not allowed to take a used model engine onboard
( even not in my luggage! ) and not even a new engine on board.
This was the new rule now in USA after 11 sept.
So I have to dismount my motor and throw it in the trash container, together
with my emty fuel can.
But I brought my motor with me back to Denmark by using a dirty trick, ( I
will not tell about this here ), and only because the motor was so small.
This would not be possible with more - or bigger engines.
So be sure to check with your airlines before departure if you want to take
model engines with you on a domestic flight within the USA.
Just to end my story, it took only three minutes to check in with British
Airways in Chicago on the way back to Denmark.


Roger Morrell