SEN-500 November 13 2000
- Category: Archive 2000
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News and Reports 2000 - second half
SCAT Electronic News 13 November 2000 issue 500
Table of Contents
US FF Champs
free flight modelers in Montana - Gies
OZ Easter 2001 - Smith
SW FAI Challenge -info needed - Zeisloft
Sky Scraper Contest - Barron, Ellis and SCAT
Extended Max - Amen - Wagner
Temperature/Humidity Effects on Model Engines - Mattes
More on Antenna - Katyba
Strands vs Props - King
Prop simulations - King
As with the Las vegas meet the week before is is somewhat pleasing
to further confirm that meteorology is not an exact science.
The weather was great and Sunday in particular was what can be called
a BlueBird day. Unfortunately I was so focused on my flying that
I neglected to collect the FAI placinasg. But I will note that AA did
demonstrate convincingly that he has not lost it by making the
7 minute flyoff round to winf F1B. He beat John Malkin, Mike Mulligan and
Larry Norvall in that order. Second place man Malkin [again !] getting
308 seconds with the others close behind.
FAI events CD, Lee Hines will get us the results.
free flight modelers in Montana
My name is Karl Gies and I live in Lewistown, Motana. I don't of many free
flighters living in Montana, actually just four. I would like to contact
other free flighters in this area. My interests are primarily rubber powered
models, mostly old timer.
OZ Easter 2001
Just wondering how many of you out there promised your loved ones a
holiday in Australia to co-inside with the OZ W/C's and can't back out
Will there be a a few extra international competitors attending the
Easter world cup event in Narranda to make extending the mortgage (yet
Please post your reply either here or to me....
[Phil , ... the question is not who wants to go to OZ but rather
what you are doing in NZ to organize a World Cup meet that is
'close' to the OZ meet so people can take in both !]
SW FAI Challenge -info needed
Please post for me on the SEN that I need information for placing the
order for "personalized" trophy plaques from my contest. The following
who placed at the contest did not indicate on their registration form if
they want a trophy or want the $15 to go to the Junior FAI Team Fund. I
need a decision from: Bob Critchlow, Doug Joyce, Vasily Beschasny, and
It is nice to see my report in print. Thanks. I plan to send also it
to Chris Weinrich (NFFS) along with some photos.
[To Jon and others , the sucess of the SEN is made by you readers
being writers too. So thank you for your contribution]
Sky Scraper Contest
Fellow Free Flighters,
Andrew Barron in a 11/10/00 email message stated,
"A disappointment for some is
that SCAT (Southern California Aero Team) has stated that despite earlier
positive encouragement from them, they are removing America's Cup Status
from our FAI events, both what was flown on Oct 29 and what we will hold
on Nov 18-19, citing their desire that there be 30 days notice (not sensible
in this case as a December date would likely encounter winter weather).
On behalf of our participants, I have made an empassioned plea for our
friends in SCAT to reconsider. Nonetheless, even if they hold fast in
their decision, we organizers commit ourselves, and we encourage Northeast
FAI fliers and all other participants, to not allow our contest effort
and enjoyment to be held captive by the Southern Californians!:)"
For your information is the email I sent to Andrew prior to the above
Andrew and Art,
Tom Coussens, Pierre Brun, Roger Morrell and myself (the SCAT officers and
AmCup administers) have discussed the recent events regarding the Skyscraper
contest. We have unanimously made the following decisions:
1. The initial contest results will not be counted for AmCup. The Saturday 2
rounds did not meet the AmCup 5 round minimum. The flyers that completed
5 rounds on Sunday will not be counted because it was after the announced
2. The rescheduled Sky Scraper annual will not be counted for AmCup results.
There have been very few rescheduled contests in the ten years of the
AmCup.Most of been due to loss of flying field. Because of the numerous
weather canceled contests this year, we wrote specific guidelines into the
2001 AmCup Rules. This states a recommended 30 days notice. The rescheduled
Skyscraper is only 3 weeks notice. This is insufficient notice for those who
previously traveled to the initial contest.
We realize that the local flyers will most likely be disappointed but we
believe this is the most fair decision that can be made in this difficult
This incident as caused us to reconcider the 2001 Rules. We are looking at
specifying the difference between a rescheduled contest and a canceled
contest. Other mitigating factors are:
a) Several AmCup contests within weeks of the reschduled contest.
b) If the Skyscraper rescheduled contest is granted
AmCup status, other weather-canceled contests this year would ask for the
same treatment before the end of the year.
We request that you send out a correcting message that the rescheduled
Skyscraper contest will not be an AmCup contest. Roger Morrell will
facilitate the use of SEN to help communicate this message.
Even though I was clear it was unofficial, I apologize that my initial
comments to Art that the AmCup points would be likely.
Sincerely, Jim Parker"
This was a very difficult decision, we strove to make the decision which
would be most fair for all involved.
We have worked to maintain East, Mid and West parity. We were pleased with
the advent of the new Wawayanda field and look forward to many new flying
Sincerely, Jim Parker
Extended Max - Amen
Roger, Amen to Doug's comments about changing the max. As a CD that would
be a night mare if you are running 36 events over a two day period with the
FAI events mixed in with all the rest. I would be probably lynched by the
contestants. Joe Wagner
Temperature/Humidity Effects on Model Engines
The other day, ambient temperature about 45 degrees F, I was trying to
get a Cyclon 15 to run on 80/20 fuel and was unsuccessful. It would run
for less than a second and quit no mater what the needle setting. A few
days prior it ran fine, albeit not too fast, when the temperature was
over 60. I played a bit with head clearance to no avail.
I would like to see some discussion on the effects of ambient
temperature and humidity on engine performance and optimum compression
ratio for both FAI fuel and high nitro content fuels. That is should
one add or remove head shims as the temperature goes down. Back in the
Rossi 15 days I believe we used to go to lower number plugs, 2s and 3s
which were hotter/higher compression, for cool weather. This would
indicate the need to remove shims for the same plug as temperature
More on Antenna
MR Roger Morell
I want to inform the information concerning the message of the
Antenn as dippol (two beams on 51 sm long) in max the size, that
corresponds(meets) approximately to range 144-156 MHz,
I use for search of aeromodels in field conditions two years. Also I can
confidently confirm its(her) advantage before usual antenna. The maximal
signal transmitter decreases up to a corner in 30 degrees, that allows
effectively to find model. Accordingly, the reduction of length of beams
antenna, results in reduction of its(her) sensitivity, and consequently
also possible(probable) application antenna on the crossed district and
by search of model in crops (corn, wheat etc.).Antenn-dipole as directed
antenna has advantage and in the sizes, in comparison with others
directed antenna. Anyway, during seasons 98-2000 years I had no problems
with search of the models, and as helped the comrades. I think, my words
will be confirmed by(with) many Ukrainian sportsmen in categories F-1-A;
B; C, and as other sportsmen, with whom I had pleasure to communicate at
stages Word Cup.
P.s. I am sorry for "machine" translation with Russian on the English
language. If someone will interest details of a design
antenna-, she(it) is present at any help
literature. This elementary radio engineering device.
Yours faithfully, Sergey Katyba.
Strands vs Props
I ran some simulations for a variety of F1B props with a variety of motor
runs (No of Strands). The motor runs vary from about 50 secs for 26
strands to ca 28 sec for 34 stds. I have not included the runs or the
Height attained as the duration is what we are after. In general all the
props work better with less strands but not to the same degree. A careful
study of the data will show that the AA prop really works well with a long
run (26 Stds) whereas the Sebenman, Doring and the Hepperle props tend to be
a little more efficient with shorter motor runs. The differences are small
and subtle and the best way seems to be to use a longer run for all. The
case for 28 strands is strange and maybe an anomaly in the program, though I
don't know why this should be so as the rest of the cases are vary consistant
in trend?? It seems to be oddly inefficient for all the props and is a bit
of a mystery.
DURATION (Props Compared)
(This just compares Duration directly between props)
Seibenman Doring Ruyter A.A . Stephanchuk Schwartzbach Hepperle
26 Stds 376 375 370 377 369 366 378
28 Stds 354 354 348 351 347 344 358
30 Stds 362 362 357 359 356 353 367
34 stds 339 345 339 342 338 337 349
DURATION (Compared in % to the AA Prop
(This compares duration in percentage terms)
Seibenman Doring Ruyter A.A. Stephanchuk
26 Stds 99.73% 99.47% 98.14% 100% 97.88% 97.08% 100.27%
28 Stds 100.85% 100.85% 99.15% 100% 98.86% 98.01% 101.99%
30 Stds 100.84% 100.84% 99.44% 100% 99.16% 98.33% 102.23%
34 stds 99.12% 100.88% 99.12% 100% 98.83% 98.54% 102.05%
(This shows the percentage gain or loss compared to the AA prop for the
different motor lengths)
Seibenman Doring Ruyter A.A. Stephanchuk Schwartzbach
26 Stds -0.27% -0.53% -1.86% 0.00% -2.12% -2.92% 0.27%
28 Stds 0.85% 0.85% -0.85% 0.00% -1.14% -1.99% 1.99%
30 Stds 0.84% 0.84% -0.56% 0.00% -0.84% -1.67% 2.23%
34 stds -0.88% 0.88% -0.88% 0.00% -1.17% -1.46% 2.05%
Note: This shows more clearly the differences in the way the various props
respond to different motor runs.
I hope this may be of interest. I have attached graphs in Exel which make
every thing a little clearer. Also I include an Exel sheet for the strange
but seemingly very efficient, Hepperl Prop. It is a raelly odd shape and who
knows if it would work as well as it appears from the simulation. It appears
to work well with shorter motors.
PS the problem I metioned about bugs in the macros to our simulation is
apparently something to do with my own Exel software. Ian Kaynes has not had
the same trouble, so you can run all the macros without fear, I hope !!!
A sumary of the results on prop simulations.
To show more clearly the results of the prop sims. here is a short summary.
For the long run 26 strand case, the best props are the AA and the Hepperle.
(a rather unknown quantity). with the Hepperle just 0.27% better.
The worst prop by far, (over all the tests), is the Schwartzbach, (nearly
3.0% down) and the Stephanchuck (just over 1.0% down but much better with
more strands). With 26 strands the Ruyter prop is not so good either, (1.86%
down), but is also much better with more strands, which is how Pym uses it to
For 28 and 30 strands the situation changes.
As the strandage gets higher the Schwartzbach gets progressively better and
with 34 strands the 3.0% disadvantage drops to ca 1.5%.
Note however that over all the highest duration comes from a long run using
the AA prop (26 strands), with the Hepperle showing a slight, (0.27%)
The Seibenman and the Doring come into their own at ca 1.0% better than the
AA. The Hepperle is an extraordinary ca 3.0% better!
For 34 strands, the situation is similar to 28 and 30, except that the
Seibenman drops to ca 1.0% worse than the AA.
In general the the AA prop is still the best except for the 'unknown'
Hepperle prop and the Seibenman and the Doring props may warant more looking
at, for motors of more than 26 strands. Of course, this is purely a
simulation and these results are wide open to errors of many kinds. What it
does show, I thionk, is that the differences between props are very small and
the real gains come from getting the most out of longer motor runs. The
Hepperle prop is unusual in that, although like Alex's, the pitch increases
towards the tip, Hepperle's increases even more at the very tip whereas
Alex's and others wash out their tips. This may present problems with the
Hepperle. The angles may be too high at the tips causing tip, stalling and a
much lower performance than predicted.
Thanks to William Gannon for his domation to support SEN.