SCAT Electronic News 6 February 2001 issue 540
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SCAT Electronic News 6 February 2001 issue 540
Table Of Contents
=================
FAI Tan II rubber status - Clapp
More on extended first round for Mini's - Tribe
Maxmen Entries - Slobat
F1A Paper - Fantham
Change of company name - Ginder
Lost Hills Grass - Ulm
Closed Loop verse Open Loop Functions - Bradley
Extended minis - O'Dwyer
AN EXPERIENCE ABOUT F1B TRIM - Masaru Koike
Controlling F1A line tension and speed -- Barron
San Valeers Annual
Bob Wiehle - Brun
FAI Tan II rubber status
========================
Feb. 4, 2001
At mid year (2000) the factory tried to formulate around an ingredient
that was less that optimum for Tan II. This resulted in two very bad
small batches that we had to buy, but which were not resold by FAI,
as these batches were totally unsatisfactory for modeling.
Upper management got involved at this point and started checking
out production costs for Tan II and soon announced a price increase.
August/September batches were satisfactory for f1b testing, but not
satisfactory for f1b contests. These batches were sold to AMA/USA
modelers and have yielded reasonable performance.
The November batch had high hysteresis losses and thus was sold
as "kit" rubber.
Due to e-mails and test data sent by many of you to FAI, several of
which were forwarded to the factory, upper management became
upset by the lack of good contest product and decreed that a
solution had to be found.
After much laboratory research and testing, factory personnel feel
that good product can once again be produced.
The next step is for a medium size batch of 1/8" Tan II to be run to
the improved specifications. We expect to have test data of this new
material by the 2nd week in March. If this batch is of good quality
then a full size run will be manufactured.
Please keep in mind that all Tan II batches that are fabricated must
be purchased by FAI. We pledge to not knowingly ship/sell Tan II to
our worldwide customers that is not suited to their needs.
We also would like you to know that we have a modeler who is a
retired polymer chemist as well as a major world chemical
corporation looking into the Tan II quality problems that have
occurred during the last half of 2000. The results of this study have
yet to be finalized.
Please be assured that we have been working diligently to once
again have quality rubber for our customers.
Thank you for your support, patience and understanding.
Sincerely,
John Clapp
FAI model supply
More on extended first round for Mini's
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
At Poitou in France, they now have a 7 minute first round Max in the =
Mini events; what a miserable contest it has now become.
I used to look forward to it, but I am in two minds whether to bother =
this year.
Peter tribe
Maxmen Entries
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Roger, with less than 2 weeks left, I have received 100 entries for the =
Maxmen. Many from outside US, but several from US, especially =
California, have not entered yet. Deadline is 2/12. gb
[If you look at the ntry form you will that there is a
high late entry fee - so take heed and get your entry in]
F1A Paper
=========
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Roger,
I remembered that a paper I did on F1A in 1993 is viewable on the web at: -
http://www.vengi.demon.co.uk/forum_f1a.htm
This gives more detail on the Engergy considerations. F1A fans might like
to take a look.
Mike Fantham
BBC
(British Bunters Club)
Change of company name
========================
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Custom carbon props is now called Freds Prop Shop. I sill build All size
props out of the finest carbon/epoxy. Call for prices at 559-229-4189.
Lost Hills Grass
================
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Roger....In regard to grass seed for Lost Hills, I think that we have
serious problem. Because or the area's aridness and extreme alkalinity, I
think that it may be very difficult to find a grass that would survive
and propagate. Our best shot would be to ask the advice of the local
county ag. department. Allen
Closed Loop verse Open Loop Functions
=====================================
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Roger,
I am glad to see the issue I opened about early DT using altitude and time
being discussed. We need to work out, with the FAI governing body, what is
really legal and what is not. I agree with Martin Gregorie and think it is
legal. An open loop system has no feedback path that allows and infinite
amount of adjustments, a close loop system does.
Since using two input, altitude and time, results in a non-reversal action,
DT'ing the model, this is an open loop system. You cannot "go back" to
gliding. There has been some comparison to mechanical function on models,
(variable pitch, torque sensor), as being illegal under this rule. They are
not illegal as they are not a closed loop system. You simply do something
because something else happened. A mechanical timer releasing levers is an
example of an open loop system. Under some peoples reasoning a fuse burning
through a rubber band causing the model to DT could be illegal!
>From the electronics point of view, I am an electrical engineer, a close loop
system has feedback. In other words, it is constantly providing control to
some function. Automatic speed control on automobiles is a good example.
The amount a throttle applied to the engine is varied according to the load,
like when you are going up hill or down hill.
An example of what could be done with models using a closed loop system would
be using a 3 axis sensor, (pitch, roll, and yaw), on an F1C model. The
sensor, which by the way is available and used by the RC helicopter flyers,
would send signals to a microprocessor, technically a microcontroller, as to
the position of the model in its 3 axis's. These signals would be compared
to a preprogrammed flight path and the corresponding correction signals would
be sent to servos controlling the rudder, stab and ailerons. The results of
this is the model is trimmed out by changing the programmed flight path.
Since once the ideal flight path is establish there would be very little need
do worry about trimming or test flying. Literally the first flight on a new
model could also an official flight.
This, closed loop verse open loop, could change the whole aspects of flying
FAI Free Flight models, as did the builder of the model rule did. Where do
we want to go with this is a personnel decision we all have to make?
Comments are encouraged.
Jim Bradley
Extended minis
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Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Retraction!
After deep thought(?) I retract my approval of longer than 2 minute
max's in the mini events. It would eliminate flyoffs that are like the
desert after a hearty meal.
John O'Dwyer
AN EXPERIENCE ABOUT F1B TRIM
============================
Author; This email address is being protected from spambots. You need JavaScript enabled to view it.
AN EXPERIENCE ABOUT F1B TRIM (Masaru Koike)
Mr. Roger Morrel
I'm F1B flyer of Japan. Concerning Peter King's article : A
QUESTION ABOUT F1B TRIM (2 February 2001), I have similar
experience. I made propeller blades that have large diameter 640mm
for trial. Motor was 26-28 strands of 1/8 FAI TAN2. The model has
VIT, rudder and wing wiggler controlled by timer. The model starts
with vertical burst clime, but immediately it transient to cruise
with slow rate of climb, after that straighten and turn left after
about 20 seconds from start. Motor run was 40-45 seconds. Total
climb height was not so bad. It glides with right turn.
This phenomenon was not cured by any trim of rudder or wing
wiggler etc. The only solution was to reduce the diameter of the
propeller.
While I don't know exact reason of this phenomenon, I suppose
that Peter King's comment is going into the most important part.
Sincerely,
Masaru Koike
Controlling F1A line tension and speed
======================================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Ken Bauer raises the question whether it is better to raise or lower
the back of the stab in the moment before launch to get the best height
gain. My limited experience with this leads to the opinion that whether
to raise or lower the stab depends on how much tension is being achieved.
In the dead calm, it is hard to reach the high levels of tension (much
more than 25 pounds) needed for a good launch, unless one jacks the back
of the stab up, and it may be important to do that early in the
acceleration to encourage tension build up, and also it may be
important to do that just before launch, because, as the model is being
brought overhead there is the potential for a drop in tension.
On the other hand, I, and perhaps other, experience (especially in windy
conditions) that when the angle of the line is in the 45 to 70 degree
range, a lot of tension does not translate as much into speed as one would
like (it is like the model runs into a wall, wanting to rotate but not
race forward as much as one would like). In that situation my experience
is it is nice to bring the stab down some.
Between ten and five years ago, I implemented that stab control as
follows. The back of the stab was set fairly high for straight tow (to
accomplish the first aims mentioned above) and then when the hook was
nearly bottomed out, in the 20 to 25 pound range (after unlatch at about
15 pounds), an arm from the hook would mechanically pull down on the line
to the stab (I modified the hook a little to get more downward movement
and to register higher tensions). When set properly, if the tension were
to start to drop, the stab begins to come to lock in at least a certain
amount of tension.
This works when one has a direct single line from servo to the stab.
[Back then I was controlling the servo using Ken Bauer's vintage controller,
programmed in analog.] My more recent models do not have this function,
because I have switched to using the Stamov pulleys at servo and tail for
better precision in setting the glide and better bunt actuation force.
In principle one could provide force input from the hook to the current
computer-based controllers to command the servo accordingly. I don't
know yet, among achievable tension & speed profiles, which produces the
best height gain, but I suspect one want to keep the tension in the 30 to
35 pound range through most of the acceleration and launch phase. The key
is ending up with both high speed and rapid rotation at the launch.
Andrew Barron
San Valeers Annual
==================
SAN VALEERS 51st New Millennium ANNUAL
& 18th ANNUAL 7 ROUNDER
APRIL 8 & 9, 2000 TAFT, CA.
A NATIONAL CUP & AA SANCTIONED CONTEST
3 MILES EAST OF TAFT ON GARDNER FIELD ROAD
CANNON BALL RUN
SATURDAY 6:30 TO 8:00 AM
RULES:ANY GAS MODEL 7 SEC ENGINE RUN. TIME TO THE GROUND.
TOTAL OF BEST TWO FLIGHTS WINS!!!!! $3.00 ENTRY FOR UNLIMITED
NUMBER OF FLIGHTS.
AMA CAT II & NOSTALGIA CAT II(ALT*) (WEATHER PERMITTING)
SATURDAY 8 TO 5 SUNDAY 8 TO 3 BOTH DAYS
1/2A GAS A GAS P-30
B GAS D GAS
CATAPULT GLIDER
C GAS MULVIHILL (ALL FLIGHTS SAME DAY
A-1 STRAIGHT TOW H. L. GLIDER FOR EACH ENTRY)
1/4A GAS(15SEC VTO,12SEC HL) A/B/C NOSTALGIA
1/2A NOSTALGIA INTERN'L POSTAL COUPE
SLOW GAS* (9 Sec) 1/4A Flyoff 7:30 to 7:45 AM (Slow gas
flyoff @ 5:30 PM)
F1A NORDIC - FIB WAKEFIELD - F1J SMALL POWER
SATURDAY 9 AM TO 3 PM
7 ROUNDER RULES: 1ST ROUND 9 TO 10 AM WITH 3.5,4,& 3 MIN.MAX FOR F1A,F1B,& F1J
RESPECTIVELY, AT CD DISCRETION(WEATHER PERMITTING) THEREAFTER, EACH ROUND WILL
BE ONE HOUR.(3 MIN MAX) (2 MIN MAX F1J) FLYOFFS WILL BEGIN AT 4 PM
BOB HUNTER MEMORIAL
RULES:ANY GAS FREE FLIGHT AIRPLANE. 15 SEC. VTO, 12 SEC. H.L.
HIGHEST SINGLE FLIGHT TIME (NO MAX) SUNDAY MORNING 6:17
TO 7:17 AM
ENTRY FEE ($1.00 PER FLIGHT) SPONSORED BY MIKE THOMPSON
PERPETUAL TROPHY : A PERPETUAL TROPHY FOR THE HIGHEST TIME IN
ANY AMA GAS EVENT WITH AN ORIGINAL DESIGN FLOWN BY THE
DESIGNER OF THE MODEL
(PREVIOUS WINNING DESIGN NOT ELIGIBLE) SPONSORED BY RALPH PREY
*SLOW GAS RULES: No builder of the model rule, no auto
surfaces, single bypass stock engines only(except TD's.049-
.051),15% nitro max, three maxes and one flyoff to the ground.
BOM RULE enforced on AMA and Nostalgia events except as noted
above.
*Nostalgia per rulebook no. 7 except motor runs which shall
be:10sec HL,13secVTO 1st 3 flights,8 & 11 on 4th flight, 6 & 9 on 5th and all
other flights
*****Free Raffle for K & B 3.5 for all gas power flyers*****
MERCHANDISE AWARDS (engines, kits, fuel, rubber, wood, etc) TROPHIES FOR JRS
CD: TERRY THORKILDSEN (805)495-6135
ASST. CD: RALPH PREY (310)671-8695
REGISTRATION $4.00 ENTRY $4.00 JRS FREE
JUNIOR EVENTS: CATAPULT GLIDER, H.L. GLIDER, 1/2A GAS, P-30
********JAY SLOAN ON THE FIELD DINING HALL ALL WEEKEND********
"JUST BRING YOUR MODELS AND SLEEPING BAG AND HAVE FUN"
Bob Wiehle
=========
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Bob Wiehle memorial service will at the 1 st Presbyterian church of Encino.
4963 Balboa blvd
Encino CA 91316
Saturday
2.24.01
10.AAM
Pierre
...................................................................
Roger Morrell
