SEN 925 - 12 Jan 2005

SCAT Electronic News 12 January 2005 issue 925


Table of Contnets
SCAT Annual
2006 Jr Team Selection Information Bulletin Number 1 Jan 2005
FAI Stamp - Schroedter
announcing issue #14 of Free Flight Quarterly - Montes
Fw: Eloy field condition
News from Eloy
SWR notice - Nelson
One-shot bagging for wing panels - SkyKieng
56th Annual Inter-City Meet - Shailor
F1C Best Climb Angle of Attack - Bogie
zero lift - Brokenspar
Model change - Segrave


DATE: Feb. 18-21, 2005
PLACE: Bissonette Mirage Field, Lost Hills, Ca.
SCHEDULE: F1G, H & JP - Friday, Feb 18th
5 rds., 45 mins. each, starting at 12:00pm
F1A, B & C - Feb. 19th & 20th
7 rds each day, starting at 8:00 am
Reserve day - Feb. 21st.
It has been determined that foward folding props in F1C
are a violation of Rules B.17.4.b, and will not be allowed

- U. S. competitors can copy entry form and mail in with fees (e-mail
entries from U.S. fliers will not be excepted)

- Non-U.S. competitors may e-mail entry form and pay upon arrival

- All non-AMA fliers must pay a $28.00 AMA affliation fee

- Entries will be considered late if not received by Feb. 13th

- Current Sporting Code will apply

COST: F1G ,H & JP $10.00 / event
F1A, B & C $25.00 / event
CONTACT: George Batiuk
1759 Southwood Dr., San Luis Obispo, Ca. 93401 U S A
Ph. 805-546-8231 FAX 805-546-0700
E-mail - This email address is being protected from spambots. You need JavaScript enabled to view it.
LOCAL MOTELS: Lost Hills Motel 6 - ph 661-797-2346
Lost Hills Days Inn - ph 661-797-2371

DATE: Feb. 19th
PLACE: Wasco Valley Rose Country Club
PROGRAM: Dinner & Americas Cup award presentation
COST: $20.00 / person $10.00 / person under 17


NAME: ______________________________
ADDRESS: ______________________________
CITY, ST. & ZIP: __________________________
COUNTRY: ______________________________
FAI LICENSE NO. _______________________

F1G ($10.00) _____________

FIH ($10.00) _____________

FIJP ($10.00) _____________

F1A ($25.00) _____________

F1B ($25.00) _____________

F1C ($25.00) _____________

BANQUET ($20.00) _____________

BANQUET < 17 ($10.00) _____________

TOTAL ENCLOSED _____________




Southern California Aero Team
SCAT Annual
Bissonette-Mirage Field Lost Hills, CA March 5 & 6, 2005
An Americas Cup & National Cup Contest

Saturday, March 5 Sunday, March 6
Main Events: 8:00 AM Start Mini Events: 8:00 AM Start
Seven 1 Hour rounds, 3 min. Max Five 1 Hour rounds, 2 min. Max
F1A: rd 1, 240sec max F1H: rd 1, 180sec max
F1B, F1C & F1P: rd 1, 300sec max F1G & F1J: rd 1, 240sec

FAI Events Flyoff schedules TBA
1st round times count

National Cup Events
Saturday, 8:00 AM - 3:00 PM: H.L.Glider & Nostalgia Wakefield
Sunday, 8:00 AM - 2:00 PM: CAT Glider & Classic Towline Glider

Entry Fees: $20 for 1st FAI event
$5 for each added event & all Nat Cup events
Juniors Welcome! Only pay $2/event! Award for Junior High Time!
[Juniors are 18 years max in 2005 to qualify]
Awards in all events! Bob White will run Nos Wake event

Contest Directors:
Roger Coleman Lee Hines
4737 Boyar Ave 376 Magnolia St
Long Beach, CA 90807-1238 Costa Mesa, CA 92627
[562] 428-8542 [949] 645-4850
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AMA & Lost Hills memberships are required. Sign-up at the field!
Many FAI & AMA records have been set in past SCAT Annual!
AMA Sanction #05-0078

2006 Jr Team Selection Information Bulletin Number 1 Jan 2005

The Jr Team Selection Committee has submitted the 2006 Jr Team Selection Program
to AMA and anticipates quick approval. The 2006 program is largely the same as
the previous program. The age requirement is the junior must be under the age of 19
throughout the entire calendar year of 2006.

The program primary construct is based on the contestantƒds performance in his
or her two best 2005 Americaƒds Cup Plus (AmCup+) contests and his or her
performance at the 2005 Nats. The first AmCup contest is almost here, January 15-16,
2005 at Eloy Arizona and it will count in the 2006 Jr Team Selection Program. Like
the last program, there will be a Pre-Nats (July 31) contest combined with the
regularly scheduled NATs events (Aug 1-5, actual event dates tbd).

The AmCup+ contest will be the thirty 2005 AmCup contests plus up to 6
additional designated contest that will be announced via Jr Team Bulletins. Clubs and CD
that have quality FAI contests that are not an America Cup contest and are willing
to support the Jr Team selection program are requested to send an offer to host
F1A,B,P events to Jim Parker . The Jr TSC will select the contests
that will provide the best opportunities for all juniors across the country to
participate. These contests will be announced in future Jr Bulletins.

The FAI has declared F1P as the 2006 Jr World Championship event. The Fresno FF
club, MaxMen and the Southern California Aero Team (SCAT) have committed to
providing up to six 1cc Cyclone engines to Jr program participants. Walt Ghio will be
coordinating this project. More details to follow.

Weƒdll close this bulletin with the Jr Program Mission Statement.

The junior team selection program exists to provide a substantial opportunity to
young Free Flight modelers who have demonstrated a high degree of interest in the
sport and the willingness to continually improve their flying skills and the
performance of their models. They must demonstrate a degree of proficiency of
competing with their models without direct adult involvement. The purpose of this
program is to provide a fair process of selecting the Junior Free Flight flyers to
compete in the Junior FAI Free Flight World Championship currently scheduled for
the summer of 2006 in Germany.

George Batiuk
Jim Bradley
Art Ellis
Jim Parker

2006 Jr Team Selection Committee

FAI Stamp
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Along with many others, I am very disturbed over the fact that FAI is
now insisting that we pay $50 for an FAI stamp in order to compete in
the two World Cup contests here. It is not so much that we can not
afford the $50; rather this cost really amounts to the straw that broke
the camel's back. Free flight is no longer an inexpensive hobby. The Max
Men and the Sierra Cup are the most costly contests.

As I see it, we are now required to pay to compete in the World Cup
competition whether or not we intend to compete. The vast majority of us
here have neither the money nor the time to seriously compete for the
World Cup. But for Europeans, it is a different matter. They can reach
most of the WC venues in a day's travel.

Last year I had the option of paying $80 to AMA to qualify for the Team
Finals. If I had chosen not to, I still could have entered any of the
competitions. This year I am interested in entering the America's Cup
contests, but I have no desire to compete for the World Cup. (Yes, Walia
and I go the Germany every year, but our apartment there is so small,
there is no place I can even store my models much less work on them.)

I strongly believe that FAI should not require those who will not be
competing for the World Cup to buy their $50 stamp.

George Schroedter

announcing issue #14 of Free Flight Quarterly
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As many listers of SCAT subscribe to FFQ, it may be of interest to
announce the new issue. As usual, there is a wide variety of articles to
cater for the different preferences of the readers. Vintage enthusiasts
have the Senator plan with two articles about the Senator, one by Jim
Moseley and another by one of the best Senator flyers in the UK, Chris
Chapman. Chris also presents his high performance
traditional-construction F1B. Christian Gugger describes the
construction of a mould for CF D-Boxes as used in F1B and F1A models.
Tetsuo Itoh describes his "Monster" 900 mm wingspan UHLG, the article
includes a photo sequence of the discus launching procedure, as well as
a link to a video of the actual launching by the author. Bill Henn
writes about his latest and probably best flying rubber scale model,
the Giant Scale 42" Ta 152H. Model aerodynamics are catered by
articles from Jean Wantzenriether (effect of stab profile on stability),
Chris Stoddart ( first part of a survey on Dynamic Stability of the
model), Sergio Montes ( on the drag of free-wheeling propellers).
Articles on modelling history come from Devon Sutcliffe in NZ and
Malcolm Abzug in USA, with Chapter 1 of the autobiography of this noted
aerodynamicist, reminiscing about the late 1930's model publishing scene
in NY. There are construction techniques from Thayer Syme and Scott
Dobberfuhl, and more, including Gil Morris' discussion of "the wall",
the dreaded resonance phenomenon in F1C geared models.

The cover of this issue, with table of contents, can be viewed in our
website: , where you can download as
well the video with the discus launch by Mr Itoh.

Hope you will enjoy it

Sergio Montes

Fw: Eloy field condition
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More from Eloy!

Hi Everyone: I have a few reports on the field at Eloy, and at this
point, all is great. The current storm track has not reached as far as
Eloy, and the field is dry. Walt Huhn talked with George Talent and
George reports that they have had no rain. Others have reported the
same. If this current storm here in So Cal misses again, the field
should be great.

Eloy locals also report that the field will dry out in a day if it does
get rained on.

Later, Kevin Sherman

SWR notice
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Hi Roger,

Southwest Regional: The weather forecast for Eloy has improved rapidly
over the past few days. ACCU Weather now forecasts lots of sun and
reasonable temperatures for the contest period. Field conditions should
be optimum with little or no dust. I will be on the field this Thursday
to welcome early arrivals.

See you at Eloy,

Elmer Nelson

One-shot bagging for wing panels
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Roger, I put this account together for Martin Gregorie, but it might be
of interest to some SCAT readers who still think about building their
own aircraft. It is a shock to realize that a large wing can be put
together within the space of a few hours measured on a clock face rather
than my usual time frame of flipping over months on a calendar!

Hi, Martin.

At first I could not see how I could make a wing panel in a one step
bagging process. But I ended up being dragged kicking and screaming into
the 21st century of wing construction.

Let me see if I can explain the Phil Barnes' one-step bagging process --
as I will use it.

First, of course, you have the foam core ( I opted to have the foam
cores cut by a professional) along with its attendant "beds" (the
outside parts - top and bottom that are like female molds.)

Patterns for the carbon cloth are cut from 12 mil Mylar sheet. They are
waxed using a paste car polish

If one wants to include a top coat of paint then the top Mylar is spray
painted with epoxy (that is, if fuel proofing is needed, otherwise,

The cloth is sprayed with 3-M 77 to hold the fibers in place. The 3.5-Oz
carbon cloth is cut to approximate size and placed on the Mylar
patterns. (The R.C. wings use a veil of 1 Oz glass, which I eliminate
because of weight considerations)

The pre-warmed epoxy is applied to the cloth which is then rolled out
and de-bulked using rollers .like a carpet seamer. (This must be done
with care as the roller can pick up a strand of carbon and strip it out
of the cloth) From Phil's video one can see the reflective appearance of
the cloth changed as it is compressed with the yarn strands pressed down
to fill up the normal voids between the weave. Of course excess epoxy is
sopped up.

The cloth is then trimmed around the edges to fit the Mylar outline.

After contact-cementing the ply ribs to the ends of the foam core I then
add a strip (3/4") of uni-web carbon material sprayed with contact
cement then fitted to the nose. This will underlay any gaps left by the
main cloth material not quite conforming to the nose.

The foam core is placed between the Mylar sheet like ham in a sandwich.
The leading and trailing edges are taped together.

Phil uses a two-bag system. The inner "bag" is made from 4 mil plastic
drop cloth material having the bleeder cloth on its is merely
folded around the Mylar sandwich. The whole works is then placed inside
the usual Nylon bag for decompression using a vacuum pump ( I have a
really great one I got from Bob Mattes)

The two beds are placed on the OUTSIDE of the package to conform the
sandwich in matching the external shape of the airfoil. Weights are used
to hold the top down tightly.

I use an electric blanket for the cure . set for about 90 degrees.too
much heat during the early part of the cure is to be avoided.

(I'm using the low viscosity Pro-Set Epoxy with the middle cure hardener
.that provides the lowest viscosity of the three choices.)

When de-bagged, after curing, the trailing edge and leading edge are
then smoothed out.
Of course the leading edge is the tricky part and must be handled with
care. Because of the bulk of the cloth I'm not sure how accurate the
nose will turn out on my very thin section. This is the reason for
adding the strip of uni-web carbon and what makes this technique
possible. (Out-of -date systems don't attempt to form the nose in the
molding operation so the leading edge must be shaped out of wood then
added after the fact.)

Putting in spars and such is a different matter. In my case, since my
tubular spar is full depth, I'm opting to cut/melt the tunnel for it
after the panels are formed. It was suggested that I use urethane glue
rather than epoxy as it will expand to fill any voids. The expansion
does worry me in that it might lever the carbon off the foam core; so
perhaps it should be cured with the panel under compression.

One aspect I really like in my case is that I don't have to worry about
what I'm going to cover it with! If I use the Mylar spray technique I
don't have to worry about a paint job either!

Now please understand that this is a very clipped version as the
borrowed two CD video I watched ran well over an hour or so!

Hope to hell I can remember everything

best, bill g

56th Annual Inter-City Meet
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The Detroit Balsa Bugs are pleased to host the 56th Annual Inter-City Meet
scheduled for June 18-19, 2005.
It will be held at the AMA field in Muncie, Indiana.
We will also have FAI qualifications on both Thursday and Friday, the 16th
and 17th.
So, for a long weekend, you will be able to get three days of qualification
time towards the program.
Large FAI events will be held on the 18th, small FAI events the 19th.
We will also hold AMA and NOS events for National Cup points
This is an America's Cup contest.
No Super Max.
Flyers are being put together. Email me if you'd like to get one.
Hope to see you there!
Bill Shailor

F1C Best Climb Angle of Attack
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In SCAT News 923, John Barker queried, "Does less lift equal less drag."
Basically that is true.
For wing sections there is one angle of attack where the lift is zero. At
zero lift of the wing, there is no drag due to lift. That angle of attack
goes negative as the camber of the wing section increases. Thus, in the climb

mode, it is best to climb the model at its zero lift. To do this is not easy.

It takes a number of flights to determine the tail setting for climb. One
way would be to DT at engine cutoff and time the descent.

Hank Cole had a method for determining the angle of attack for zero lift.
Something about drawing a line between the trailing edge of the section to a
point on the camber line at perhaps the 50 percent chord. Of this percent I
am not sure.

The angle between this line and the horizontal line for the wing section is
the angle of zero lift. In any event, nothing beats flight testing.

Bill Bogart

zero lift
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( Gil Morris has given me this lesson, more than once
....with illustrations )

For a section such as present day F1C models use,
zero lift is obtained with the byproduct
of a large negative pitching moment.

( from memory......)

An illustration of the forces at work at zero lift,
shows negative pressure on the upper surface to the rear,
and negative pressure on the under surface forward.
These forces cancel each other, thus zero lift, -
howeever, with the byproduct of a negative pitching moment.
At velocity, this force can be quite large.

This was illustrated dramatically at a team finals at Lost Hills
some years ago. Somebody had climbed out...and the engine
didn't quit. So all eyes were on the model.
It soon went over the top and came screaming straight down,

We had a perfect view of the model coming down, power on.
It finally hit between two pole positions. People all around.

We could see the wing twist. ( not fluttering ! )
Apparently symetrical, each side, with considerable deflection.
Unbelievable, actually, for one of those Ukranian wings,
that seem very stiff, trying to twist them, while you're considering
droping another 400 USD.

Then it hit. In the Lost Hills sand. *

Galbreath came over to look at it.
I think he was the CD -
In that trumpeting voice that we all have heard
many times over the years, he told us to come over
and look at the imprint the wing had made in the sand.
There was a curved groove, to either side of a pit
in the middle: the center wing panels showing a bow
of about an inch on each side.

Galbreath had obviously seem this act before...

The guy came to pick up his model. Not much comment.
I seem to remember....Menanno ?..

*...someday it's not going to miss

Model change
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If you had a rubber model with a freewheeling prop, and then wanted to
change to a folding one, what trim changes would you have to make?
Less decalage?
More rearward CG?
Or what?

And would it then be more efficient i.e., fly longer times?

On another tack, has anyone investigated some of the old pre weight limit
wakes and also the 4 oz type to see why they seem to fly well with very low
dihedral and HUGE fins? On the face of it, they should wind into the ground
and if not, the glide would be poor for it has been shown that large fins
cause the ship to try to spiral dive(that not the best description).
Investigation such as installing polyhedral, and/or lowering the fin size?

Any offers?

Mike S

Roger Morrell