SCAT Electronic News 28 February 2001 Issue 550
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SCAT Electronic News 28 February 2001 Issue 550
Table of contests
=================
Another [in]famous SEN FAI rules reader survey
Thermistors - Crowley
Center of drag - 007
New CIAM Rep - Crowley
Do Magnets Suck? - Johannes
Timer brownout. - Kowal
Tailbooms - M&K via Parker
Another [in]famous SEN FAI rules reader survey
================================================
The CIAM bureau meeting will happen at the end of March. We would
like to conduct a reader survey on rules proposals.
Please send your reply to This email address is being protected from spambots. You need JavaScript enabled to view it. by March 15.
Question 0.
I am from XXXXXX = where XXX is the country you live in. [not
necessarily your citizenship]
Proposals ..
- All three F1 events, A,B,and C have a German proposal to disallow DT as an
excuse for an attempt. This is to limit the advantage the unscrupulous
might have with RC DT systems.
1. FOR or AGAINST proposal to count a flight less than 20 seconds
as am attempt - if the model D/Ts [Note that this does not
specify why the model D/T's - as that cannot really
be determined by the timer keeper]
.......
- F1J (1/2 A)
o 5 second motor run
o 7 flights
o 180 second max
o score = total of 7 flights
2A. I do NOT fly F1J and I am FOR or AGAINST the proposal to change
the F1J rules as above.
2B. I fly F1J and I am FOR or AGAINST the proposal to change the
F1J rules as above.
.......
- F1K (CO two)
o 1 cc tank
o certain flight limitations set to limit flyoff participation
3A. I do NOT fly F1K and I am FORor AGAINST the above rules changes.
3B. I do fly F1K and I am FORor AGAINST the above rules changes.
........
- It is anticipated there will be some discussion although not on the agenda
about the use of geared propellers on F1C models.
A) As seen in the propellor article by Jack Norris in the NFFS '98
Symposium (page 19) use of a gearbox for F1C is a scientific
inevitability.
B) There will be at least two sources of engine/gearbox combinations
available soon. (Nelson is considering offering one under $500)
C) F1A and F1B have endured dramatic technical device adaptations in the
lsat several years without deliterious effects to
participation.(electronic timing/actuation on F1A and Variable
pitch/delayed propellor action on F1B front ends)
4a. I do NOT fly F1C and I and FOR or AGAINST forbidding geared motors.
4b. I do fly F1C and I and FOR or AGAINST forbidding geared motors.
5. I have or intend to have a F1C model with a geared motor during this
year.
There is a Uranian proposal to Require teams in the World Championsships.
If they do not have sufficent people a flyer from
another event may time. The object is to increase the quality of
timekeepers.
6. I and FOR or AGAINST the proposal to require teams participating in
a World Chamsp to supply a time keeper.
There is a Ukrainian proposal to have an 'all star' [offically
known as FAI team] team in the FF World
Champs. This would be made up from the highest placing people in the
World Cup, who are not a defending champion or in a National team.
The World Cup administrator would be the 'Team Manager'.
7. I am FOR or AGAINST the propsal to have an all star team in the
World Championships.
8. List the FAI FF events that you fly e,g, F1A, F1B, .. ets
The CIAM meets in Lauzanne, Switzerland on 22 and 23 March, 2001.
Long time participant Geo. Xenakis is being substituted by Bill Bogart.
Dan Tracy is still an observer for the Team Selection Committee.
Send your reply to This email address is being protected from spambots. You need JavaScript enabled to view it.
Thermistors
==========
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Can anyone help me find a couple of Fenwal thermistors new part
no.112-202EAJ-B01, old part no. GB32J2.These are the ones that were used in
George Xenakis' thermal sniffer. Fenwal has a $1000 min. order and $100 min
from their distributors. It's 2000 ohms,ratio 7.04, time constant 4 sec. I
guess an equivalent would be OK. Anyone know what Turner was using in the
ones he was making?
Paul Crowley
Center of drag
==============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Roger,
Jean Wantzenriether has asked me to relay this question for discussion
in SEN.
Could you please publish it?
regards
Sergio Montes
----------------------------------------
Help is needed in settling this question:
Consider a wing with a large dihedral. At what height above the wing
root lies the drag center of the wing?
In a computer modelling of the glide or powered climb, the wing drag
produces a pitching-up moment. The Drag Force is relatively easy to
calculate, it is the Profile Drag, increased by the Induced Drag. But in
the case of the moment due to this force, which is the moment arm? In
full size aviation, the dihedral is always small, so the usual reference
books do not deal with this question.
One may locate the center of drag of the profile drag, by integrating
the drag force along the profile of the wing, according to the spanwise
lift distribution of the wing.
But for the induced drag? We know that tip vortices are important. How
important?
And if one wants to work with a center of drag, in a statistical sense?
Many thanks for any help of a scientific nature. Until now one has just
groped in the dark and assumed, not a very happy or productive
situation.
Jean Wantzenriether
This email address is being protected from spambots. You need JavaScript enabled to view it.
New CIAM Rep
=============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
This is an open letter to all Dist. 7 FAI program participants to inform
you that we have a new CIAM Rep.,Bill Bogart, recommended by George Xenakis,
the previous Rep., and approved by AMA pres. Dave Brown. No input was sought
by Brown or Xenakis in regards to this action despite Brown's knowledge of
the FAI community's feeling that it must be included in the process.
Due to the short time before the next CIAM meeting , March 21, we
will try conducting an online poll via SEN regarding the CIAM agenda in
order that Bill better understands the United States FAI flyers position on
the various items.
I personally want to thank George for all the work he has done on our
behalf for many many years. Good luck and thanks.
Paul Crowley
Dist. 7 FFTSC
Do Magnets Suck?
================
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Hi Roger,
Recently, in a discussion with my friend Bob Mattes, I was describing my =
efforts to determine the material from which a plug in an aluminum =
engine mount was made. I commented that I had touched the plug with a =
magnet and felt no" suction". Bob thought that was pretty funny. He had =
never heard of magnet action referred to as suction. He quickly pointed =
out that if magnets really do suck it could have very serious =
ramifications. Such as, if you said someone had a " magnetic =
personality", you were really saying that their personality sucks.
I await enlightenment from the SCATEN readers.
Bob
Timer brownout.
==============
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
On my Stamp based timers I immediately jump to DT if the
timer is reset and the towhook is in the released and back position.
I did this because once on a cold day, when my battery was low, my
timer reset on low voltage when the plane started to bunt. It performed
about two or three bunts on the way to contact with the cold cruel earth.
This was in a model with two servos that were both trying to
move at the same time. after I delayed the second servo for 100 miliseconds
or so the problem went away entirely. I have left the software unchanged
just in case.
On my PIC based timers I do not use such a curcuit since they do not brown
out till around 3 volts or so. Your servo will move so slowly by then it
should be noticable when you hook it up.
Also I use a Battery tester for RC (sorry for the mention) on board battery
packs. It tests the battery under load and gives a very good indication of
the remaining life in a battery. They are available in the states for under
$15.00 U.S.
Hope this helps.
Ken
Tailbooms
=========
Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
Roger,
Below is a short piece from Segey Makarov regarding the latest batch of tail
booms
Thermals, JIM
About the gold tail booms. The difference not only the color (and size a
little bit). It is another technology and the other person do it. After
Alexandr Muhin dead, we noted, that the quality of the tail booms became
worse. Last spring we broken several booms after usual DT. At the same
time we founded some guys in S.Petersburg, who produce the booms with
good technology and use very similar cone, like M&K. We tested it and
now we get and use for our self only this tail booms. They are lighter
and stronger, the aluminium seam is better. I try to explain you the
difference:
Old technology (from Muhin), several steps of gluing:
Step 1. Wrap the aluminium around the cone, glue carbon, harden.
Step 2. Sand-paper the carbon. This is informal phase, depend from the
qualification of worker. It is very easy to make too thinly some places.
Step 3. Glue the external aluminium.
New technology (from S.Petersburg), one time gluing. This technology use
the cone of opposed surface (conical tube). The pie with Al-C-Al,
prepared with epoxy, place inside the conical tube. Then the rubber tube
place inside the pie and with air pressure into the tube harden epoxy.
As a result you get the tail boom with better characteristics.
Now I 'll explain you how to adapt the new tail booms (a little bit
smaller) to MK nose.
- If the parts of nose (left and right) not glue together yet. Just
sand-paper the end of the 2 half about 80 mm in order place it inside
the tail boom, then glue the 2 half with some effort at the end.
- If you have ready nose part of the fuselage. Cut the end of the nose
(step part) in vertical and horizontal plane, sand-paper the end. It
works, we tested.
Sergei.
...............
Roger Morrell
