SCAT Electronic News 23 April 2001 issue 572
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SCAT Electronic News 23 April 2001 issue 572
Table of Contents
=================
More timer news - Van Wallene
Roller paper tapered forms - Brokenspar
Science Olympiad - Brokenspar
2001 San Valeers Annual - Thorklidsen
Making tailbooms - Augustus
Re: Rolled Tail Boom- Issue # 571 - Lipori
Rolled tail booms. - Kowal
More timer news
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Hi,
Two subjects:
- results on servo tests
-more on ABAS (articulated bunt animation system)
-After a discussion with Rudi Holzleitner who experienced some strange
servo behaviour flying in early morning cold and afternoon 'heat', I did
a test on temperature stability of analog servos. The results are:
For a 10 degreed (C) temperature change, the servo position drifts about
1.4 degrees. I tested 'cheap' Taiwan made servos as well as high quality
(Graupner) servos. The results are the same. After discussing the matter
with Francois Moreau, he tested this on his model. He reported that a
temperature change of 20 degrees made the trailing edge of his
stabilizer drop by 0.4 mm. Taking into account that a fuselage might
warm up in the sun, flying in early morning Lost Hills and afternoon
heat, 20 degrees is a rather conservative figure.
It gets even worse. Analog servos also suffer from a so called 'dead
angle' This means when trying to steer the servo disc about 1.5 degrees
it will not move. So for small changes (i.e. VIT to glide or similar)
the servo control is very inaccurate. Adding temperature drift, keeping
model trim becomes a real challenge.
So what's the cure for all this?
Torleif (Danish timer) already implemented a digital control for the
servo by bypassing the servo's analog electronics.
For those who use a standard servo, Graupner will release this month a
small digital servo. It is temperature independent, and due to improved
regulating characteristics, the dead angle is reduced to about 0.4
degrees. Test results will follow shortly.
-Recently Makarov reported only a very slight (negligable) gain in
performance when steering the stab during on line acceleration (OLA).
But this under the assumption that a wing is infinitly stiff. A fellow
dutch F1A flyer / aerodynamic engineer (Ben Videc) redid this
calculation / computer simulation, but this time taking the deformation
of the wing into account as well. Results showed that (in particular
D-boxed) wings deform during OLA dependent on line tension. In fact,
the higher the line tension the more the wings twist inducing a negative
'warp'. Due to this warp the optimum tailplane angle must be reduced
(more up elevator). This up elevator creates more line tension which in
its turn will cause even more wing twist etc. until a balanced situation
is obtained.
In conclusion, when line tension increases during OLA, the tailplane has
to be steered progressively 'up'. Rene Limberger flew an 'old style'
Russian type model. He found out an optimum VIT setting of as much as 10
mm at the trailing edge of the stab. This sound a lot, but taking a 2 mm
up elevator (VIT during OLA) as an optimum value for an infinitly stiff
wing, this translates to about 5 degrees average negative wing twist at
high line tension. For an 'old style' carbon D-boxed wing this could
well be the case.
Regards, Allard
Roller paper tapered forms
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Gents: This is a case of another invention of the Detroit Balsa Bugs,
along with down thrust, stab tilt, the Penny Plane ( Rodemsky ),
the S hook, many others...
Crowley told me about this method one friday nite, probably in the early =
'70's,
at the New Casino Bar. ( That's where we all met every friday nite,
until Shailor got his Corvette stolen. Then we moved out near the
GM Tech Center in a sports bar with darts and jukebox. No pool table )
The selection of glue or adhesive is central to the task.
A 'glue' that is wet, and must cure by evaporation, is..all wet.
At the big end it would take forever to cure, and would probably shrink
with time.
We used Hobby Poxy ( Crowley ) or probably Sig 2 hour Epoxy at the
time,
then readely avaiable.
More sophisticated epoxys are now easy to obtain ( viz, CST )
I made one for F1C booms in the early '70s. Brown paper, 5/8 dia core
steel rod.
The working diameters are 1.5 tapering to .625, 48 inches long.
The core rod extended beyond, each end.
I think we drew the long taper by snapping a line ( blue chalk )
We layed out the paper on a long wall in our new shop
in Madison Heights ( this set the date ).
Russ Hansen helped.
We rolled it up on the rod on a bench with a good surface, all wet with
epoxy.
( Crowley says he put epoxy just along the edges, 2 inches wide,
with a dab here and there to hold it together )
After it cured, it was sanded smooth, one end in a block,
the other in a big drill motor.
Booms with Kevrar/ 1/16th balsa /Kevlar were made, many times.
The balsa was pre formed, with joints fitted, on the same form.
The Kevlar/balsa/Kevlar was laid up, wet with epoxy ( probably Sig, 2
hour ), then
spiral wrapped with plastic tape ( Mylar,for parting, ),
with pressure supplied with Ace bandages.
After the cure, it was fun getting the part off the form.
The work was clamped to a bench, the other end out on a horse.
Five guys were recruited ( during lunch break )
to grasp the thing togerher along it's length. Everybody take off your rings.
On singal we applied twist in unison. " Don't squeez it ! Clockwise,
Charlie ! "
It popped off nicely if the epoxy was given enough time to cure and harden.
These days, we use a company that can turn any taper might invent.
I think Ken Oliver found and trained these people. Lynco Grinding.
Bell Gardens, CA. Usually aluminum. With a black coating. ( They won't tell
me what it is ). These forms take the heat for curing
aluminum/carbon (Kevlar )/ aluminum booms.
Not that the paper forms would'nt take the heat.
So, that's what I know...
Science Olympiad
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My email address for John Clapp must be out of date. May I use this
wonderful medium to communicate ( and perhaps elicit other
reccomendadtions )...
My grandson, Kai, age 12, is flying at state level Saturday, 4/28.
We have the following rubber to work with.
Which has the most horsepower, and otherwise has no bad features,
( explosive, as Bob White once characterized some rubber he sent me for =
indoor use ) ?
10/97
2/98
2/00
( yes we will make some tests, plot some curves, to fly under the
ceiling with
this beastly airplane, ( 5 minutes ? ). Any help will give use a head
start )
Brokenspar
( Grandad )
2001 San Valeers Annual
=======================
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2001 San Valeers Annual
by T. Thorkildsen
This year had been strange weather wise and although we
had had nice clear weather for about 3 weeks before the
contest, a couple of storms were approaching around the
contest weekend so we were rolling the dice and hoping for
the best as the weekend approached. I arrived around 11:00
P.M. at Lost hills and drove through rain driving over the
grapevine so I was keeping my fingers crossed. We woke up
Saturday to a cold and windy morning so decided that we would
make it a Cat 3 contest. Norm Peterson and Lynn Pulley flew
cannon ball in the wind which is for the best two flights and
the chases were pretty tough but Lynn hung in there to
collect the win for $25.
Even with the 2 minute max the chases were hard enough
that a lot of flyers just waited to see if conditions would
improve with the wind. You could see by the clouds and black
sky in different sections that there were some major storms
around us and I understand that Taft got caught in one of
them but all we got was a little drizzle. Only two events
were flown Saturday other then Cannonball and that was C Gas
and B gas. Lynn Pulley and John Keller flew in the hard wind
earlier in the day but the weather calmed down for the last
hour of Saturday, which allowed some of us to fly B gas in
some pretty decent weather.
Sunday we awoke to a cold (35?F) but classic beautiful
day with hardly any breeze and it stayed that way with little
wind for the whole day for absolutely perfect conditions. We
decided to stay with cat 3 since we didn't want to take any
chances and flew all the events that we didn't fly the day
before. First up was the Bob Hunter Memorial for the highest
single unlimited flight on a 15 sec motor. Everyone got
their cold motors started okay and we had fairly tight
competition in this with Guy Menanno taking the win with 8:44
on a motor run that was about =BD of what the rest of us were
using on a giant F1C type looking model.
1/2A Gas had some decent competition with 3 flyers
making the 5th max and only 6 seconds separating 1st and 2nd
with Mike Thompson and Terry Kerger doing the honors and
Kerger was using a Spacerod that he just competed and it goes
really well. Matt Kruse had an overrun on his 6th but did
really well to get that far flying a Kiwi no less.
Out of all the FAI events F1J had the most competition
with Fred Ginder, Dave Rounsaville and Guy Menanno all maxing
out. They were all flying originals except for Ginder who
was using a faithful Maverick powered by a CS .049. Guy
scored the win with Cyclone power and Dave settled for 2nd
dropping his 7th flight. Dave hails from New Jersey and used
a trusty TD for his effort. Guy Menanno won a beautiful 1/2A
boom donated by Ken Oliver for his first place. Some of the
other FAI events didn't get a lot of flyers since a lot of
them had already left Saturday but both John Sessums and
Brian Van Nest were clean in F1B and F1A respectively with
Bill Booth only dropping 2 seconds in F1B also.
Martyn Cowley and the boys were having fun flying the
mini events and Martyn and Lee Hines were both clean in F1H
followed by Lee Hunt with a mini master and Bob Norton with
an original.
Catapult glider was won by Norm Smith. He had 3 maxes
besting the rest of the 6 flyers. Johnathan Keller was our
lone Junior catapulter and he flew on Saturday and was having
a lot of fun.
In 1/2A Nostalgia Larry Bain was the upset flyer with 7+
maxes to score the win for $50 which Norm Peterson had
graciously donated. We were flying Cat 3 Alternate rules
which the San Valeers have used for a number of years and
even then a lot of flyers had strings in spite of the recent
flack over engine runs. Larry flew a T bird powered by a
Killer Bee. Great flying Larry you beat out some great
flyers like Secor and DeShields! If you look over the
results you will see that we had a full assortment of 1/2A
motors in this with Hornets, Foxes and Medallions also. In
ABC Nostalgia, Bob Beecroft scored the win with 8 maxes with
a Veco .19 powered Lucky Lindy beating out DeShields with his
Frisco Kid and Steve Bruno with a HH.051 powered T Bird.
Steve Bruno seem to be flying T Birds or Stardusters in
a whole bunch of events with his lovely wife Kim doing the
timing honors. Steve came all the way from Oklahoma City and
sure didn't go home empty handed since he won slow gas flying
a Super tiger powered Duster and also won the Raffle for a
brand new K & B 6.5. He was a happy camper about that and we
were happy that he could make our contest and that he had a
good time, since both him and his wife are really nice people
and a pleasure to be around.
In D Gas Daryl Perkins and Lynn Pulley both had good
strings but Lynn dropped with an O/R on his 7th and Daryl on
his 12th both using Nelson .41 motors and Miller B's and
Miller Light models respectively.
A Gas had the most competitors with 10 contestants
battling it out. I dropped my 14th max with my Astrostar 600
for 2nd and Dave Anderson scored the win with 15 + maxes with
an original. This also gave him the high time for a model
flown by the designer, which Ralph Prey sponsors. Good
flying Dave!
After a perfect day of flying we finished up by handing
out some great prizes including contest wood, kits, engines
etc. What makes a contest more enjoyable for the CD is the
people that helped and I want to thank Guy Menanno my co-CD
and his wife Sheri for helping run the table, along with Fred
Ginder, Al Mennano, Lee and Lois Hunt and everyone else that
helped that I may have forgot. Also thanks go to Allen Brush
of Starlink, CST (Matt and Quinn), MRL, Rick Keller, Tom
Laird, Bob DeShields, Dick Zackman, Ralph Prey, Mike
Thompson, Al Menanno, Lynn Pulley, Lee Hunt, David Brix ,
Norm Peterson, and Fred Ginder who all donated great stuff
along with all our other club members that helped pay for the
expenses.
I want to thank everyone that came and those that stayed
through to Sunday to enjoy a perfect day of flying. I hope
everyone comes next year for a great weekend of flying with
some good competition and you can bet on some great prizes.
1/2A Gas 2001 SAN VALEERS ANNUAL 1/4A Gas
1 M. Thompson AME.049 Satellite3750 1 Bob DeShieldsTD.020 FriscoKidd518
2 T. Kerger TD.049 Spacerod 744 2 Del Adam TD.020 Zeek 469
3 Matt Kruse TD.049 Kiwi 600 3 M. Thompson TD.020 Hot Head 411
4 D. Anderson CS.049 Original 455
5 D.RounsavillTD.049 Original 323 A-1 Straight Tow
1/2A Gas Jr. 1 Lee Hunt Mini Maxer 574
1 Cody Secor(JTD.049 Orbiteer300326
B Gas Cannon Ball Run
1 M. Thompson KB 3.5 Satellite 4697 1 Lynn Pulley Original 153
2 T. ThorkildsKB3.5 Astrostar 60476 2 N. Peterson 134
3 John Keller KB 3.5 Satellite 4360
4 Lynn Pulley S.T. 21 Slopy 245 C Gas
1 Lynn Pulley Nelson.36 Killer 360
Slow Gas
1 Steve Bruno ST .19 Starduster 360 P-30
2 Lynn Pulley ST .23 Slopy 250 1 Bob Van Nest 311
3 N. Peterson Torp .40 Satellite216
D Gas
A Gas 1 Daryl PerkinsNel .41Miller Lit1500
1 D. Anderson KB 3.25 Original 2075 2 Lynn Pulley Nel .41Miller B 750
2 T. ThorkildsKB3.25 Astrostar 61874
3 M. Thompson KB3.25 Satellite 4458 HLG
4 Lynn Pulley Aero15 Y2KKB 450 1 M. Cowley Gold rush 315
5 Steve Bruno ST.19 Starduster60415 2 Lee Hines Sweepette 257
6 D. Wagner Satellite KB RR.1327 3 Norm Smith 206
7thD. Rounsaville 276
8thCody Secor(Jr) 201 Jr. Catapult
9thBill Alnes Cyclone .061Orig 118 1 Johnathan Keller 48
10tGuy Mennano 109
ABC Nostalgia
1/2A Nostalgia 1 Bob Beecroft Veco19 Lucky Lind960
1 Larry Bain Killer Bee T Bird 886 2 Bob DeShieldsHH.051 Frisco Kid438
2 Bob DeShieldHH.049 Frisco Kidd710 3 Steve Bruno HH.051 T Bird 415
3 Randy Secor Fox049HoosierHotsh589
4 Steve Bruno HH.049 T Bird 310 Catapult Glider
5 Norm PetersoMedallion Geef 250306 1 Norm Smith 360
2 Lee Hines Swepeete Cat 330
F1H 3 Brian Van NesCopper Cat 306
1 Martyn CowleStamov Bunter 600 4 M. Cowley Gold Rush? 298
2 Lee Hines Master Twanger 600 5 Lee Hunt 280
3 Lee Hunt Mini Master 408 6 John Sessums 212
4 Bob Norton # 71 346
F1B F1A
1 John Sessums 1110 1 Brian Van Nest 900
2 Bill Booth Burdovichar 928 2 Hector Diez 650
Coupe Bob Hunter Memorial
1 Bob Van Nest 583 1 Guy Menanno No. 7 8:44
2 T. ThorkildseKB3.25 Astrostar68:37
High Time AMA gas flown by Designer 3 M. Thompson KB3.25 Satellite 6:59
Dave AndersoKB3.25 Original 4 Lynn Pulley Original 6:46
F1J
1 Guy Mennano Cyclone061heavense1224
2 D. RounsavilTD.049 Original 1049
3 Fred Ginder CS.049 Maverick 812
4 Del Adam MPJet.40 Ellipsy 564
5 M. Thompson AME.049 Satellite 549
6 Bill Alnes Cyclone .061Genie 520
Making tailbooms
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Roger,
I have read with interest all the discussion about build small,
straight tailbooms. I used to make F1J booms and even entire
fuselages by wrapping balsa around a pool cue and then reinforcing it
with full-length 1/8 strips of 003 CF. I quickly discovered that a
dead-straight boom was almost impossible to make, and equally
unnecessary. It doesn't matter if it is straight, as long as it holds
its shape. Once the incidence and rudder position is set up, the
crate will fly the same with a slightly crooked boom as with one
which is optically straight. I always set them up so the curve is up
or down, rather than off to one side.
BA
Re: Rolled Tail Boom- Issue # 571
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> Re: rolled tail boom mould.
> ===========================
> Author : This email address is being protected from spambots. You need JavaScript enabled to view it.
. Other SEN readers may have found the same
> problem with the finished booms: the thin balsa (1/32" for Coupes, 1/16"
for
> Wakes) can warp easily in the drying
> process after moulding it to shape. In some
> cases several tries are needed to get a perfect boom. Any ideas to prevent
this
>
> happening?
> Sergio Montes
Bonding silk or porous tissue to the thin balsa with several coats of dope,
prior to rolling the tube seems to help with warping as well as increasing
the tubes strength. After rolling and gluing the seam, check for warps. If
there is a bow in the tube, wet the convex side only and place back on the
mandrel to dry. Repeat until satisfied with the straightness, then sand and
again apply silk or tissue and dope to the outside of the finished tube. The
next and most important step is to allow the finished boom to cure out
without removing it from the mold for several days. Leaving it outside on a
sunny day will accelerate the process. Works for me!
Bob Lipori
Rolled tail booms.
=================
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Something I picked up off a plan somewhere was to cut the boom material
out of two pieces instead of one. Align the grain with the centerline of each
of the individual panels and the boom is much more stable. As I stated in an
earlier note I double spiral wrap the outside of my booms with very fine Kevlar
thread. This stabilizes the booms even more. If you are going to wrap the outside
of the boom with Kevlar you can also form the boom using "C" grain wood which
makes the boom absolutely stable. It is however extremenly fragile without the
Kevlar holding it together.
Ken
..............................
Roger Morrell
