theampeer.org
February 1997
the
Page 1
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President:
Ken Myers
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phone: (810) 669-8124
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phone: (810) 220-2297
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Howell, MI 4848843
phone: (517) 546-2462
Board of Directors:
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phone: (810) 772-2499
Ampeer Editor:
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Walled Lake, MI 48390
phone: (810) 669-8124
Ampeer subscriptions
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world wide.
The Next Meeting:
Date: Thursday, Feb. 6 1997 Time: 7:30
Dublin Community Center, just N. of the village of Union
Lake on Union Lake Rd. across from St. Patrick’s Church
Just View It!
CHVideo is happy to announce a PostHoliday Sale on all of our Electric Flight
Videos.
Videos available are:
•'94 KRC - 1 hour
47 minutes - VHS
SP
•'95 KRC/Mid
America - 1 hour 50
minutes - VHS SP
•'96 Mid America 1 hour 37 minutes - VHS SP
•'96 AMA/NEAC Electric NATS - 2 hours
25 minutes - VHS SP - T-160
Sale prices are as follows:
•1 video - $18 •2 videos - $32
•3 videos - $42 •All 4 - $50
...the prices above include shipping to
addresses in the US and Canada, including
APO and FPO.
Videos may be ordered by sending a check
or money order to:
What’s
in this
issue?
CHVideo
310 S Jefferson St
Sturgis, MI 49091
NOTE: Make check or money order
payable to: Clay Howe
This Post-Holiday Sale will remain in effect
until at least January 31, 1997. Please
mention in your order where you saw the
sale notice...
For more information, e-mail:
clayhowe@net-link.net
clayhowe@juno.com
KRC Videos
1994 and 1996 KRC videos may be
purchased from: (the 1994 is not the same as
Clay’s)
Real-Tour Productions
Box 466
Perkasie, PA 19944
Tel.: (800) 958-4336
Price is $23US a piece, which includes
shipping for each VHS tape
View It - New Props - Small Stuff - More on SR Techniques - Lazy Bee
Review - Choosing the Right Prop - Some plane ratings - Motor Mount
Source - ModelAir-Tech H-100 Belt Drive
February 1997
The Ampeer
Keep an eye out for SR Batteries to announce tapes of the
‘96 Symposium.
page 2
My strategy is to learn rubber-power skills by flying
models of comparable size and weight starting with sport
models, such as Bostonians, eventually going on to
Prop News
rubber-powered scale, such as peanut and dime. Then, learn
E-power by flying the sport types; that's where I am now, I
Did you ever notice
think. Then, move on to E-power in small scale types.
how easy it is to miss
After that, I'm not sure, but think of the possibilities. I think
product notices that
there's a Grummann Widgeon in-my future. Or, maybe for
might have an affect on
indoors, one of those Curtiss pre-WWI single-place biplane
us. In case you missed
flying boats. Then; eventually, maybe a Blom and Voss
this press release, here
BV-238, which would have to be RC, of course, because it
it is from Model
had six engines. (Yes! You did read that correctly. I am
Aviation confident that my RC flying ability will be up to the job by
Master Airscrew G/F Series Propellers in new sizes from that time.) After that, the sky's the limit!
Windsor Propeller Co., 3219 Monier Cir., Rancho
This is not a completely nutty- idea.- According to
Cordova, CA 95742 - tel. 1-(916) 631-8385 or fax 1-(916) September DEAF Notes, the newsletter of a highly respected
631-8386).
electric RC club in Texas, they have planned their
The four new sizes are 7 x 5, 8 x 5, 9 x 7, and 10 x 5.
second annual indoor fun-fly, so it has some appeal in other
Designed with Windsor's state-of-the-art CNC tooling, these parts of the country, too. Now, just in case you're interested
props have NASA airfoils, true helical pitch, and accurate
and want to know some sources of scale kits, here is a
balance. The new sizes remain true to the original G/F
partial list (these are rubber-powered, of course):
Series design in appearance, but they have improved
performance with more thrust at lower RPM. More sizes
America's Hobby Center
will be coming out in new and replacement pitches and
146 W. 22nd St.
diameters. For a free catalog, send a pre-addressed and
New York NY 10011-2466
stamped envelope to the company.
1 800 989 3989
Aint that interesting?
Model Airplane News had the same press release in its
Dare Hobby Distributors
January issue but stated there are 11 new sizes: 7x5, 8x5,
Tom's Patchogue Hobby Center
8x7, 9x7, 10x4, 10x5, 10x9, 11x4, 11x5, 11x8 and 11x9.
240 Hedford Ave.
516 475 8856
Small Stuff
from the November 1996 issue of:
Diels Engineering, Inc.
Silents Please
P. 0. Box 263
the newsletter of the Silent Electric Flyers of Long Island
Woodville OH 44001
edited by: Fred H. Dippel, 2 David Ct., Glen Cove, NY
11542
Gene Dubois
P. 0. Box 30053
At various times in the past I have given some favorable
Acushnet MA 02743
opinions about small electric free-flight models. It occurred
to me the other day that, whereas, in contrast to rubberEasy Built Models, Ltd.
powered models, they weigh more, so hit harder and break
Box 425
more readily. They are more like full scale aircraft in that
Lockport NY 14095-0425
respect. The ratio of power plant weight to airframe weight
716 438 0545
is more like that of full scale aircraft, also, and the weight
distribution is more similar, thus, so are the trimming
Golden Age Reproductions
requirements and so are the flight characteristics.
P. 0. Box 1685
Therefore, small electric free-flight scale would seem a
Andover MA 01810
natural combination, no? Of course! You should see some
of the great scale models at the FAC events! Remember
Don Brull's Dornier Do X? But it is not a venture to be
(cont. on next page)
rushed into.
February 1997
The Ampeer
Herr Engineering Corp.
1431 Chaffee Dr., Suite 3
Titusville FL 32780
407 264 2488
Hiline
P. 0. Box 11588
Goldsboro NC 27532
Hobby Lobby International, Inc.
5614 Franklin Pike Circle
Brentwood TN 37027
615 373 1444
Peck-Polymers
P. 0. Box 710399-MB
Santee CA 92072-0399
Penn Valley Hobby Center
837 West Main St.
Lansdale PA 19446
215 855 1268
ScienText, Inc.
48 Wnitney St.
Westport CT 06880-3753
203 221 1326
More on SR Techniques
SR BATTERlES, INC., BOX 287 BELLPORT, NEW
YORK 11713 FAX 516-286-0901 PHONE 516-286-0079
(Last month the Ampeer contained a listing of what was
available in past issues of this journal. Here’s more info
about it. You’ve got to check this out. Very helpful. km)
Techniques is a new concept in modeling. It isn't a
magazine, or a book. Instead, Techniques is an archive of
modeling knowledge and expertise. In Techniques you'll find
some of the most respected modelers in the country sharing
their personal modeling tips and techniques.
Each volume of Techniques pinpoints a specific modeling
task or problem and draws on our eight Contributors' 300 +
years of modeling experience for solutions that work. With
Techniques, you can easily build your own personal
modeling library tailored to your personal needs.
Techniques' contributors include Steve Anthony (Electric
Conversions), Larry Davidson (Old Timers), Bob Hunt
(Airframe), Dean Pappas (Flight and Aerobatics), Tim
Renaud (Soaring), Larry Sribnick (Electric Flight), Paul
Tradelius (Helicopters), and Don Typond (Finishing).
The basic idea behind Techniques is that after reading a
page 3
volume, you should be able to do something you weren't able
to do before reading that particular volume. It's that simple.
The writing style used in Techniques will give you the
feeling that you're visiting a Master modeler's shop and
looking over his shoulder while he works. Each volume is so
jam-packed with information that if a paragraph were left
out, you'd be missing something. No fluff, no bull, just pure
"how to" information. If you'd like to be a better builder,
finisher, or flyer, Techniques is for you. And, the best part is
that each volume of Techniques is only $2 plus 50 cents for
First Class mailing to your door.
There are two different editions of Techniques and you
can subscribe to either or both of them. R/C Techniques
covers the entire R/C field including Sport, Trainers,
Pattern, Scale, Giant Scale, and Old Timers. You'll find
information on building, materials, adhesives, proper radio
installation, covering and finishing. In addition, R/C
Techniques covers the trimming and flying of all kinds of
aircraft from Trainers to Pattern ships. ARF's are included,
too.
The second edition of Techniques, Electric Flight
Techniques, gives you everything you've ever wanted to
know about Electric Flight from the spinner to the battery
pack. All of the tips and techniques that usually take years
of trial and error to discover are included. If you'd like to do
it right the first time and get the most out of Electric Flight,
Electric Flight Techniques is for you.
In addition to the bi-monthly R/C Techniques and Electric
Flight Techniques, we also have Heli Techniques and
Souring Techniques. These editions of Techniques aren't
available on a subscription basis yet, but they are growing in
our archive and modelers should check in with us
periodically to catch up on the new additions in these areas.
Eventually, we plan to have each of these editions available
on a bi-monthly basis, too.
Each volume of Techniques is typically four pages in
length and a full 8.5" x 11" in size. We even three hole
punch each volume to make it easier for you to build your
own custom modeling reference library.
What makes Techniques so unique is that once a volume
comes out, it doesn't disappear. Instead, it is simply added to
the list of volumes available. In this way you don't miss a
thing. The list of information just grows and grows. At
anytime you can order the information you want without
paying for the information you don't want. And the best part
is that Techniques is only $2.00 per volume plus 50 cents
First Class postage and handling per order. Order as many
volumes as you'd like for only $2.00 each!
If you'd rather subscribe to Techniques for the year so
that you get each new volume as it comes out rather than
trying to remember to order them periodically, it's no
February 1997
The Ampeer
problem. R/C Techniques is published on the even months
of the year, February, April, June, August, October, and
December. Electric Flight Techniques is published on the
odd months of the year, January, March, May, July,
September, and November. A calendar year's subscription to
six volumes of either R/C Techniques or Electric Flight
Techniques would he $15 including First Class Postage. If
you'd like to subscribe to both editions, a total of all 12
volumes, the cost would be $30 including First Class
Postage for the year. If you subscribe to Techniques at some
mid point in the year, you'll receive all of the volumes which
have already been published for the current calendar year up
to that point.
Here's who's writing for Techniques...
Larry Sribnick, Electric Flight - Larry is the President of
SR Batteries. He has been a modeler tor 45 years and has
been involved in almost every aspect of the Hobby including
Sport, Pattern, Soaring, Slope Soaring, Giant Scale,
Helicopters, Old Timers, and Pylon Racing. He is a full
scale Instrument Rated pilot and he was the CD for the
1995 AMA Electric Nats. Larry is the founder of the
National Electric Aircraft Council and he has been a
member ot both the AMA Electric Contest Board
and the FAI Electric Selection Committee. Larry has written
for R/C Modeler and Flying Models magazines and he has
been the Electric Fight Columnist for Flying Models
magazine. He has also written for Popular Photography,
Camera 35, Photographic, Sail, and Canoe magazines.
Finally, Larry is the creetor of the SR Electric Flight
Symposium, Electric Night Fly, and Electric Indoor Fly held
each year in conjunction with the KRC Electric Fly In.
page 4
new aircraft designs and soaring related accessories and
radio systems. A modeler tor 24 years, Tim was the driving
force behind the Airtronics Vision radio system. Although he
is primarily interested in Thermal Duration soaring, Tim has
been very active in both Scale and Slope soaring as well as
Sport and Old Timer Electrics. Tim is heavily involved with
F3B Soaring Competition and he attended the '91, '93, and
'95 World Soaring Championships as a U.S. Team caller. In
'97 Tim is the Manager ot the U.S. F3B Soaring Team. Tim
collaborated with his dad, Lee Renaud, on the Aquila
Grande, Sagitta 600, 900, and XT, and the Olympic 650
designs as well as his own Cumic, Cumic Plus, Eclipse,
Legend, Legend SC, Whisper, Whisper 95, Peregrine and
Sapphire sailplane designs. Over the years Tim has written
for R/C Modeler, Model Builder, and Model Airplane News
magazines.
Don Typond, Finishing - A modeler for over 50 years, Don
is the former Editor ot Model Airplane News, Air Progress,
and Private Pilot magazines. Over the years he has been
involved in Free Flight, Waketield, Coupe, Towline and HL
Gliders as well as indoor and outdoor Rubber Scale, Control
Line Stunt, Speed, Scale, and R/C Sport and Scale. Don is a
member ot the AMA's Scale Contest Board. He is a full
scale pilot with Landplane, Seaplane, and Glider ratings.
Don has published articles and original designs in Model
Airplane News, Model Builder and Flying Models
magazines as well as having written tor Flying and Sports
Cars Illustrated magazines.
Dean Pappas, Flight and Aerobatics - Dean is an Electrical
Engineer and he has been a modeler tor 32 years. If it has
wings, Dean has tfown it, but he is particularly interested in
Bob Hunt, Airframe - Bob has been a modeler tor 45 years. Pattern and Aerobatics. He was the NSRCA District
Until recently he was the Editor of Flying Models magazine Champion in 1985-1988 and 1995-1996. He has also been a
and although he is an accomplished R/C builder and pilot,
Top Ten Finalist at many AMA Nationals and FAI Team
Control Line Stunt flying is his specialty. In fact, he has
Trials and he has competed at the TOC and Top Gun
won both the US National and World Champion titles in the events. Dean is a member ot the AMA's F3A Team
event. Bob was recently inducted into the Precision
Selection Committee and he judges and conducts
Aerobatics Model Pilots Association Hall ot Fame. Bob is
modeling seminars all around the country. For the last 13
known for his technical achievements in innovative
years he has written a column and many feature articles for
construction techniques including the "Lost Foam" process Flying Models magazine.
and triple internally cored foam wings. He has written many
articles and columns over the years and he has published
Steve Anthony, Electric Conversions - Steve is in charge of
many original designs. Bob is presently President ot Robin's Customer Services at SR Batteries. He has been a modeler
View Productions and we're hoping to have him help with
tor 35 years and is particularly interested in Electric Soaring
the planning and production ot a series ot Techniques
and Sport Scale conversions of wet designs to Electric
videos.
power. Steve was the Asst. CD at the '95 AMA Electric
Nate and he placed 2nd in both Class A and Class B
Tim Renaud, Soaring - Tim is the General Manager at
Sailplane at the '92 AMA Electric Nate. In addition, Steve
Ainronics where he is responsible tor the development of
has designed several very succeasful Electric Saliplanes and
February 1997
The Ampeer
he is a staff member on Compuserve's Flight Simulations
Forum where he specializes in head to head military air
combat. Prior to coming to SR, Steve was a specialist in
composite materials and electronics in the Marine Industry.
Paul Tradelius, Helicopter - Paul is a pilot for USAir and
he has been a modeler tor 45 years. Betore retiring, Paul
was a Lieutenant Colonel in the Air Force where he flew the
F-4 Phantom and was the Chiet Acceptance test Pilot who
flew each new F-16 betore it was accepted by the Air Force.
Although he has flown all kinds of model aircraft,
Helicopters are Paul's specialty. He has written articles and
columns for many of the modeling magazines and he wrote
The Basics ot Radio Control Helicopters which is now in its
second edition.
Larry Davidson, Old Timers - Larry has been a modeler
for over 45 years. Although his current passion is SAM Old
Timer Free Flight, he has been active in R/C, Control Line,
Free Flight Power and Rubber, Soaring, and Helicopters.
Larry was the SAM R/C Assist Grand Champion in
1991,1992, and 1993. No one else has been Grand
Champion three times in a row. In addition, Larry has won
many "Best Finish" and Spirit ot SAM Concourse awards.
Larry is a Private Pilot and he has his Instrument Rating.
Around Long Island, Larry is known for his Hobby Shop
which over the years became the best in the area. In 1986,
Larry sold the shop so that he could devote his lull time to
Old Timer competition.
The Bee Stings
from the September issue of:
DEAF Notes the newsletter of the Dallas Electric Aircraft
Fliers
edited by: Frank Korman, 9354 Forest Hills, Dallas, TX
75218-3633 - phone (214) 327-8411 or e-mail:
FranKorman@dcccd.edu
(Thought you might enjoy this one. These are very
propular planes. It was a real pleasure to get to meet
Frank at the ‘96 E-Nats in Muncie, and read his article
about the Nats in Model Aviation. Great Job Frank! km)
Clancy Aviation's Lazy Bee has become an instant classic
it seems. Swarms of the buzzy beggars seem to be
everywhere in sizes from peanut to giant scale; with
or without floats; highwing or midwing, etc. Safe to say this
plane's pizzazz is of a whimsical narure. So if you're silly
putty in the wings of a cutey read on.
The Bee comes in a box bedizened with a lazy bee
reclining in a hammock while he or she wiggles the sticks on
a transmitter.
page 5
And speaking of sticks that's what there is an abundance of
inside the box along with ribs (only 9 in the 48" version 1
built), a few formers, some 1/16 sheet, and assorted other
pieces. This is old timer constrection in a new form.
The building instructions are nicely done with good
drawings and suggestions placed appropriately. This may
not be a beginner's project, but it is not diflicult to build.
The wing goes together quickly with the rounded (about as
big as a pie plate) 10" tips setting two inches dihedral off the
the flat center section.
The tips are laminated around a form that the modeler
provides using a template in the kit. The 1/16 thick wood for
the tips is about 27" long which gives you an idea of how
wide (about 12" at the root) the tips are. I built the wing to
spec except for adding 1/16 by 1/2 strips top and bottom at
the junctare of the center and tip sections. This was done to
make it easier to adhere the covering to the center and tip
sections. A key and bolt wing hold down is shown as an
option. I used the rubber band approach as it seems
appropriate to this ship.
The fuselage is built up using traditional old time stick
teebiniques. I followed the plans adding a suggested side
access door for the motor battery, and made up a
detachable motor mount/holddown so I could easily try out
different motors. The porthole windows are cut out for
you. Clear mylar is provided for the windows.
The tail feathers are built up with laminated edges for
which template patterns are provided. The rudder is of
the all flying variety (i.e. it is all rudder with no fin). There
is a stab and elevator. A stearable tail wheel is used.
Trexler balloon tires are not mandatory, but they sure
increase the little toot cuteness factor. Using these is a first
for me, and I have found a "pump" in the form of a bulb that
might be used to clean out one's ears. You're advised not
to inflate the tires with your breath as the moisture
eventually rots the tires. (and makes the filler tube stick
together! oops km) Rubber band shock absorbers are used,
but an option using RC car shock absorbers is shown.
I covered my Bee with Airspan a verylight tissue/silk
looking mylar that requires adhesive be brushed to the
plane's surfaces. The stuff goes on fairly easy, although
"doping" the sticks gets old. I like the visibility of the hot
lime and hot red colors. I don't like how it is relatively easy
to puncture. Airspan weighs about 3 grams a square foot
(without the dope). It sure looks good on the Bee.
Templates are provided for wing and fuselage scalloped trim
(which I did not do).
My Lazy Bee weighs about 40 to 43 ounces depending on
the battery, motor, and prop. Wing area is about 630 sqs.
giving a loading of about 10 oz./sq.ft.. I've used a can
motor on a 3:1 box with a Master Air Screw 12x8 folder;
February 1997
The Ampeer
the same prop and gearbox with a Speed 500; a Kyosho
LeMans 360PT with a 2.5 gearbox and a variety of props;
and an Astro 5 turn geared 2.38:1. Six and seven cell packs
have been used. The best combo for endurance and
performance is the can motor (about 125 watts in on 7 cells)
with the MAS 12x8 and 3:1 gear box. Be sure to either keep
the folding prop from folding or use a fixed prop as a
folding folder will hang up on the fuse. I'm using an Astro
211 contrulier and it works fine. The plane is very easy to
fly. I've been handlaunching because of prop drag if ROG'd.
It certainly will ROG. It will thermal. It's is the easiest plane
(with wheels) to land that I've ever flown. Be sure to use low
rates on the elevator and rudder. It takes very little
movement to boot the Bee about.
In sum the Lazy Bee is a good quality kit that returns lots
of sporty airtime and attracts lots of approving attention.
Build yours and join me at the field so we can buzz up a
storm.
Choosing the Right Prop
(The following two letters appeared in the November issue
of Peak Charge, the newsletter of the Silent Electric Flyers
of San Diego, edited by Steve Belknap LetIFly@aol.com
They are presented here for there informational value on
selecting “the right prop”. km)
The "'Tale' of two Models” - grows a little longer
Bob Benjamin responds to Lynn Heffern's article in last
month's issue
The “Tale of Two Models" article in the November "Peak
Charge" caught my attention to the extent that I feel the need
to offer some input. I don't know John or Lynn personally,
and have no idea as to their level of experience, and so have
to hope that they will excuse me if I appear to presume to be
telling them things they already know.
What I am going to say is based on a lot of experience
with the sort of airplanes and power systems under
discussion. My first thought is, "Why did they use the Astro
25; this is much more motor and battery than that little
airplane needs". It becomes clear as I read through the
article that the model under discussion is the Sportster 20,
which has a wing area on the order of 400 sq. in., and for
which a .20- .25 sixe glow engine is called out by the
manufacturer. Perhaps it was assumed that the Astro 25
with an appropriate battery delivers power on the order of
that of those engines. My experience has been that a good
25 installation is more nearly equivalent to a four stroke 45.
That power would be OK, except that, as we know, with
electric power we can't use a “larger motor” without also
using the larger battery that goes with it. The Astro 25,
page 6
whether direct or geared, is far too much for the Sportster
20. The experience that John and Lynn relate appears to
favor the direct drive installation. I would submit that
what they are seeing is in fact the result of that
installation's being lighter; and hence allowing a wing
loading that is less in excess of what it should be than was
the case with the geared motor.
The second factor that appears to me to be "out of
whack” is the propeller selec tion. I don't have much
experience with the Astro 25 in direct drive, but the 11 x 5
mentioned for the geared installation is probably far too little
propeller for anything but a very lightly loaded airplane
intended for duration above all else. My friends and I have
flown geared sport-wind Astro 25s for years in airplanes
ranging from Senioritas to Schneider Sports; the best props
we have used are the Master Airscrew Electric Series 12 x 8
and 13 x 8. These will load the motor to about 28-30 Amps
full throttle static. Empirical data indicates that the degree to
which these undercambered props unload in flight is
proportionally greater that "gas" props, such as Rev-Up and
Zinger designs. If the 11 x 5 propeller didn't load the motor
to at least 25 Amps, which I strongly suspect to have been
the case, then the Sportster was carrying the weight of the
25 system with the benefit of only part of its power!
So, what will work? My baseline for a suggestion in my
Tigerkitten, which at 450 sq. in. area is slightly bigger than
the Sportster 20. I have flown Kittens on a geared Astro 05
and 7 cells at about 54 ox.. With this power the airplane is
docile but underpowered. The power system I will
recommend for the Sportster 20 is the same as what I
suggest for the Kitten. First choice is the Model Electronics
Corp. Turbo 10 Plus with their 6:1 gearbox, 10 1700 mAh
cells, and a Master Airscrew 12 x 10 propeller. My three
Kittens using this system weigh in at between 64 and 70 oz,
these figures yield wing loadings between 20.5 and 22.5 oz.
per sq. ft. and the airplanes are docile at low speed.
Durations are five minutes plus, and power is sufficient for
good vertical performance (like easy square loops from
level, inside loops 100 ft. high, etc.). Level cruise is easy at
well below half power. I'm also flying a Kitten on floats with
this set-up - effortless takeoffs and good aerobatics, etc..
My second choice would be a sport-wind geared Astro
Cobalt 05 on 9 cells (Yes, you can do this without hurting
the motor as long as it gets good air flow and you use full
power only for short bursts; that is, throttle back between
maneuvers). Best propeller here would be the M.A. Electric
11 x 9. Third choice would be the Astro 15 on 12 cells;
again, these are the 1700s and the propeller is the 11 x 9.
I have flown Kittens at up to 4 3/4 lb. with no problem as
long as the balance and trim are correct. This should pretty
well bracket the range a Sportster 20 conversion might fall
February 1997
The Ampeer
into.
I strongly suspect that a Sportster using the Turbo 10/10
cell combination and built carefully, using a light covering
such as silk or one of the flims, would come in at around 3
1/2 pounds and be capable of serious vertical performance.
Our experience at MEC with these motor systems in little
models is that as the area drops toward the 300 - 350 sq. in.
range, as long as the trim and balance are kept under
control, model performance accelerates toward the
unbelievable. We have chased hot 40 glow powered models
out of the sky with 3 1/2 lb. foam fighters at about 325 sq.
in. area with these systems. The temptation will be to use
less propeller Don’t do it, 12 x 8 or 12 x 10 M.A. Electrics
are the way to go!
I would suggest that the power formula that was shared a
few years ago by Keith Shaw is an excellent place to start in
working out a conversion. That is, we use INPUT POWER
as a reference, basing the calculation on the assumption of
1.1 Volt per NiCd cell, and measuring current at full throttle
static with the chosen propeller. Efficiency factors can be
ignored, as all we are doing is generating numbers to place
our project on a scale developed by using siinilar
numbers/data points derived from many other models whose
performance has subsequently become known to us.
Assuming a reasonable wing loading and configuration/trim
status that are appropriate for controlled flight, 50 Watts of
input power per pound of aircraft weight will permit takeoff
and safe flight. 60 Watts will permit basic aerobatics, 70 or
more should permit advanced aerobatics. For instance, if we
use the Astro 05 example: 9 cells (9 x 1.1 = 9.9) x 25 Amps
= 247.5 input Watts. If we put this into a four pound plane,
we get about 62 Watts per pound. In practice, we can easily
get closer to 30 Amps static from this motor and probably
shave a few ounces off the model, thereby hitting about 7075 Watts per pound.
Lest we forget the Astro 25, I will share a few
experiences with that motor. As I mentioned above, nearly
all my experience with this motor has been with the geared
version. 1 have personally flown two different versions of
the Schneider Sport Electric, Dennis Weatherly's Cloud
Dancer 40 conversion, several Senioritas, and a couple of
Goldberg Anniversary Cubs on geared Astro 25s on various
combinations of 14 to 16 cells and the 12 x 8 to 13 x 8
propeller range mentioned before. In all cases the airplanes
were nicely aerobatic, would cruise at half power permitting
5 - 7 minute flights, had docile wing loadings, and in all
cases were flown over long enough periods of time to insure
that no damage was being done to the motors using the
props described. All these airplanes, except the Cloud
Dancer, have been flown very successfully on floats without
changing any aspect of the motor-battery-propeller
page 7
combination. Also of interest is that the 1/6 scale (6-foot
span) Porterfield that I took to the US Scale Masters
Championships in 1990 used a geared Astro 25 on 16
cells. Other competitors who saw it flying while other (glow
powered) models were in the air had no idea that it was
electric.
Steve, I hope that this rambling discourse is of some
interest and that if you choose to use it in the newsletter it
will be received as an attempt to share experience in a
constructive manner. I would be pleased to share further
thoughts, answer questions, or what ever, if the interest is
there.
I really want to thank both Bob Benjamin and Bob
Boucher for their highly qualified and thoughtful
contributions. As editor, this kind of feedback is what I live
for! - Sincerely, Steve Belknap
'PROP'er Set-up is Essential for the Sportster 20
Bob Boucher of Astro recommends the correct choice of
propeller for the Sportster 20
I find that the article on the Great Planes Sportster 20
with the astro 25 is not very useful except to show what not
to do. The major problem with both models was the choice
of propeller. In my book I recommend a Rev Up 9x6 or and
APC 9x6 on 14 cells. These props will draw between 25 and
30 amps static on the bench, the motor will put out 300
watts and the shaft speed should be about 11,500 RPM. The
prop pitch speed will be 11,500 x 0.5 = 5750 feet per
minute or 65 MPH. For aerobatics like loops and rolls one
needs a flight speed of 2.5 to 3 times stall speed. At a flight
speed of two times stall speed one cannot loop. At three
times stall speed the loops are round. For this motor-batteryprop combination stall speed needs to be no higher than 26
mph and should be closer to 21 mph. If the stall speed
is above 33 mph the model will be always on the verge of
stalling and the first mistake will be the last. A wing loading
of 16 ounces per square foot will produce a stall speed of 20
mph with a Clark Y airfoil. A wing loading of 24 ounces per
square foot will produce a stall speed of 25 mph. My guess
is that the Sportster has a wing loading closer to 30 than 24.
By using a 9x4 prop the motor power drops to 190 watts
from 300 watts and the pitch speed drops from 65 MPH to
47mph. If the wing loading was 24 ounces per square foot
or more you are looking at a crash waiting to happen. My
suggestion is to use a 9x6 prop and throttle back if you want
slow flight. This way you have maneuvering power when
you need it.
We recommend a 12x8 or 11x10 on the geared 25. An
11x5 Rev Up will only load the motor to about 15 amps or
about half its potential. To make maters worse the Zinger
February 1997
The Ampeer
brand was chosen. These props are too thick for electric
flight and are not very efficient for our use. At 7000 rpm on
a 12x8 the pitch speed would be 4666 ft per minute or 53
mph. This would be too low for a heavy wing loading
of 24 oz. per sq foot. an 11x10 would give a pitch speed of
5833 ft per minute or 66 mph.
My main conclusion is that the wrong props were the only
thing wrong with either set up. Extending the wing span by
six inches might be a good idea because the wing area is too
small and the wing loading is too high. A trainer or sport
model is much easier to fly at 18 ounces per sqare foot than
at 30 ounces per sq ft.
All my best regards - Bob Boucher
page 8
both Greg and me. Put Greg’s info and this together and
you’ll be a mounting expert. km)
Dear Mr. Gimlick,
Congradulations on your new column for R/C Report.
Your motor mount article was a good start, but in my
opinion you left out one of the best, although least known.
Joe Pasquito of 168 Gainsboro Rd., Lawrenceville , NJ
08648 sells 4 different mounts. The first series looks much
like the Astro radial mount except it is aluminum, and has a
slot cut on two sides so the Astro brush holders can slide in
from the front. It also has a set screw , but they provide a
SS hoseclamp to tighten down on the motor, a much better
system. They have two sizes for the 05-15 and 25-40 . They
More Plane Ratings
stick out about 1 5/8 inches from the firewall.
from: Dave Segal
The second pair are brand new - I haven't seen them
Keystone RC Club
anywhere. They are beam mounts for the same two size
76641.2074@compuserve.com
motors . They are V-shaped between the beams with 4 beam
attach points. Between the attach points is space for the
I would like to add some additional ratings based on my
provided SS hoseclamp. Neat!! The prices on all theese
experience learning to fly with electric power planes.
mounts are a little high , but for low volume, high quality I
guess it is to be expected, and in my opinion, worth it.
1. Nitto Kitty (same as Cox Canario) ** 280 can motor,
Regarding the Stitzler mount, in my opinion, the 25-40
Benson ESC, stock prop, 5x425mah, It did fly, but was
size should be a little heavier guage metal as it doesn't stand
probably the lowest powered plane I ever saw.
much abuse. Despite this I still use it on occasion. However
I modify it some by widening one of his strap holes enough
2. Peck Prairie Bird *** Leisure 05, gear 2.5:1, HiTec ESC,
to take a special "aviation" Stainless Steel hoseclamp. This
7x1000mah, 10x6 prop, A nice easy to fly plane, but
clamp is both narrower and lighter guage stainless than
duration too short for a trainer.
a regular clamp - much superior for our usi. It was
available in three sizes that were perfect diameters for us.
3. Amptique ***** Leisure 05, gear 2.5:1, JETI30 ESC,
This system I feel is far superior to his two suggested attach
7x1000mah, 10x6 prop, 37oz., An absolute dream to fly. It
methods. I formerly bought these clamps at Home Depot
floats on lift like a glider.
here in Sarasota, but they no longer carry them. I sent one of
my last ones to Joe, who was interested. If any one finds a
4. Windstar EP (ARF)** 540 can motor, APT on/off,
source, please let me know.
7x1400mah, stock prop, 54oz. A lead sled. Slow climb and
too fast glide due to excess weight. The covering is a
Rate a Plane
From: John A. Williams
horrible "linoleum" that is unshrinkable. Turned into a great
qyetfli@worldnet.att.net
flyer by converting to .10 glow power and recovering wing
with Monokote.
Ken,
My personal favorite is still my Electrostreak with an
(Thanks Dave. The Amptique is highly recommended by
everyone. You can get one from New Creations R/C. While Astro 15 direct drive with an Aeronaut 8-5 folder as I fly no
wheels and land on grass (polo field :) I use 10 1700SCRs.
it aint pretty, it has a loveliness all its own! km)
Also I added 1/4 inch to width and depth of the fuselage to
More on Motor Mounts
make things less crowded. I have tried 12 1700s and both 10
from John Williams
and 12 1000 mAhs, but the 10 1700s is my choice.This is
qyetfli@worldnet.att.net
my ***** rating. The Electrostreak, after 8 rebuilds weighs
56.5 oz. with 10 1700 SCRs and the Astro 15G. The area is
(In the January 1997 issue of R/C Reports, Greg Gimlick 340 sq. inches, for a wing loading of 23.9 oz. per sq. foot.At
excellently covered motor mounts in his column - super job 3/4 throttle itflies like a well-behaved pattern plane.
- get this one folks. John sent the following information to
I've had a dozen or more run of the mill models, but one
February 1997
The Ampeer
not written up too much is the Modeltech slope ME 109. I
have wheels on this and with 12 2700s it goes like bloodyblue blazes. The weights and wing loadings will follow as
my memory isn't good enough. This is a **** for aerobatic
types. The ME 109 also has 340 squares, but weighs 73 oz.
with 12 1700SCRs.The wing loading is a very high 30.1 oz.
per sq. inch. It flies somwhere between a pylon racer and a
patern plane. We haven't found yet just how far we can slow
it down. Naturaly it lands pretty fast and this plane is
not for everyone - but exciting ,yes.Using Astro's chart for
watts out, that gives 57 watts per lb. I don't know if Keith's
rule of thumb is from power in or out. With an 05G and 7
cells it would be 45.7 watts per pound. The Electrostreak is
51 watts per lb. The opinion of our "experts"is to back off to
an 11-7 prop as the 12-8 is too fast and too short.
The trouble with the rating system is that for a glider flyer
it would be a *-- a hold on and pray job. This has a Master
12-8 electric wood. The P 51 of this series has more wing
area so it might be better. I have a kit unbuilt like a dozen
others.
More Ratings
From: Dave Harris
dharris1@concentric.net
Ken... I would like to submit the following ratings:
EZ Built Spacewalker **** Astro Flight 10T cobalt
15G, 12 cells and 11 X 7 Master Airscrew electric wood
prop. Steve Neu controller and 270 mah airborne pack. All
up wt < 60 oz. Will perform consecutive outside loops from
level flight. Realistic flying speed. Only downside was that
the "EZ-Built" is sort of an oxy-moron. You have to like to
and have experience "building". I only regret that radio
problems did mine in.
Modified Electro streak **** Wingspan 52" foam
w/balsa sheeting Fuse: No mods Seperate micro servos for
ailerons, wt. 60 oz., motor: Aveox 1412 2Y, Prop: Aeronaut
8 X 5 folding ( plan to try a 9 X 5), Cells 10 1700's, Airfoil:
stock - Performance: Hold on !!! Quick roll rate, vertical
performance, 5 - 6.5 minutes flight times working the
throttle. Will even slope in 15
mph winds I could probably
build it lighter for even more
exciting performance.
The New ModelAir-Tech H100 Belt Drive
Designed for use on the popular
Speed 400 motors and the
page 9
Kyosho AP-29 this can be one potent little unit. It comes in
ratios of - 3:1, 3.27:1, 3.6:1, 4:1, 4.36:1, and 4.8:1.
Recommended for 5 - 14 cells! Don’t you just wonder what
this will do on the new Astro Flight Brushless motor?
Sorry, no price came with the announcement. Send for their
newest catalog. I’m sure it will be in there.
ModelAir-Tech, P.O. Box 12033, Hauppauge, NY 117880818 Tel: (516) 979-1475 or E-mail Tom Hunt at
THunt95147@aol.com
Ai/Robotics On the Move
From Martin Euredjian comes news of a move to a new
location. He wants to assure everyone that he’s still there,
doing his ESC thing with the FX-35D. His 80 mile move is
difficult, for many reasons, but he’s still out there for you.
You can get hold of him at:
Ai/Robotics
P.O. Box 34580
Los Angeles, CA 90034
(310) 815-1745
(310) 815-1795 fax
or E-mail at 72617.2465@compuserve.com
A Buzz With a Rating
From: Dereck Woodward
woodwadd@erols.com
As a long time Bee fanatic, I better get my bit in for the
little fat fellow, the "Lazy Bee" by Clancy Aviation , with
the 40" wing - four stars **** Astro 05G, seven or eight
cells, prop 10 x 6 Master Airscrew electric wooden. Hitec
micro RX, two Futaba 133 micro servos, 250 mAh nicad,
Astro 210 controller. Weight - around 46 ounces. Controls:rudder, elevator, motor. Performance:- Not the calm weather
floater many think. It will do multiple rolls, loops, Cuban
eights and a lot of stuff that isn't in the books and that only a
Lazy Bee could stay in the air through. Strap on the floats
in minutes and she's just as hot off the water. I only gave it
four stars because I'm building a Speedy Bee and I want to
see what life is like with ailerons! The Lazy bee is probably
the most unique sports model in the air right now - one for
the extrovert flier who loves to play in the weeds!
Photos Needed!
Greg Gimlick, Current Affair columnnist at R/C Report
needs photos. He told me that “Gordon would like to
increase the electrics coverage in RCR, but I'm rapidly
running out of photos from my journeys. I'd love to show
some projects, but I need pictures from folks...” You can
reach Greg at:
76342.2271@compuserve.com or via snail mail at:
Greg Gimlick
1016 Camberley Dr.
Apex, NC 27502-8107
Attention Members
The February meeting will be at the Dublin
Community Center, not at Ken’s house. I’ll
have the pylon set-up and we’ll do a bit
more ERTP. I also plan to continue the talk
from October on choosing the right prop.
See you all at the Dublin Community
Center, 7:30, Thursday, February 6th.
To Reach Ken Myers, you can land mail to the address on
the front page. My E-mail address is:
102575.3410@compuserve.com
EFO WEBsite: http://members.aol.com/KMyersEFO/
The Ampeer
Ken Myers
1911 Bradshaw Ct.
Walled Lake, MI 48390
Next Meeting: Thursday, Feb. 6, 1997,
7:30 PM Dublin Community Center
Just N. of Union Lake on Union Lake Rd.
Upcoming Events:
April 13, 1997 Capital Area Soaring Association's Annual
SPRING SIZZLER ELECTRIC FUN FLY, Gude Drive Field,
Rockville, Maryland, Call Roy Smith at 301-279-2966 for more
information.
June 7 & 8 Tenth Annual Lehigh Valley Radio Control Society
E-Fly, Mike Stewart, 107 Taft Terrace, Washgington, NJ 07882
as CD. For more info E-mail Mike at Mike721@worldnet.att.net
or Phone: (908) 689-6981
June 28/29 - Knights of the Air R/C Club, Springfield, Illinois,
Tim McDonough, 127 S. Oaklane Road, Springfield, Illinois
62707 (Email: tpm@inw.net)
July 12/13 - Mid-America Electric Flies, Ann Arbor
Falcons/EFO, location, Midwest R/C Society Field, 5 Mi. Rd,
Northville Twp, MI Ken Myers/Keith Shaw
Aug. 2 - 5 - AMA Headquarters, Muncie, IN Doug Ward,
R.D. #1, Box 189. Irwin, PA 15642 (412) 446-5891
DWard79207@aol.com
September 20 & 21 Queen City Airport, Allentown, PA:
KRC - setup on the 19th. For more info e-mail Anthony
Assetto at 102723.2566@compuserve.com
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