IN THIS COLUMN I will write about fuel systems for Speed models.
At first glance it would seem that not many problems could occur with
these simple-looking systems, but improper fuel-delivery setups cause
many modelers to lose flight attempts, and they can also cause pilots to
turn poor times when they do make everything come together for a full
run.
This was made clear to me this spring while testing a new Formula
40 model. On the first lap the engine would burp just after takeoff; this
is not a good thing to have happen during the acceleration lap in this
event. My Speed partner Barry Tippett and I examined every part of
the fuel system, and everything looked fine. We flew it again and burp.
We then took my model and Barry’s model apart and compared
every part. The only difference we found was in the dump tube that I
had installed in the venturi. In desperation I soldered a piece of small
brass tubing with an inside diameter (ID) of .035 inch inside the tube.
We flew it again and no problem occurred.
The .125-inch ID tube I had used was large enough that when the
engine unloaded on takeoff, it would momentarily suck all of the fuel
from the tube and cause the burp. The smaller tube caused a slight
backpressure that stopped this from happening.
In the past many modelers used the black rubber bladders used in
ink pens as fuel tanks. They supplied the correct amount of pressure,
but their life spans left much to be desired. It was common for a
bladder to pop after as few as two flights, resulting in a lost attempt
and fuel sprayed all over the inside of the Speed model. They are much
better quality today.
Fisher Scientific offers black natural rubber latex tubing that
measures 1⁄8 x 1⁄32 inch. It will last a whole season without breaking; it
is excellent stuff. The part number is 14-150-5A, but before you order
be aware that Fisher requires a minimum order of 10 packages or 120
feet. This amounts to several lifetimes worth. You can purchase small
amounts of the tubing for a reasonable price from DARP Speed Pans
at (734) 266-7290.
To build a bladder tank you need a 21⁄4-inch-long chunk of the
Fisher tubing, a brass or nylon plug for the end, a Tee fitting to go
between the needle valve and the bladder, and fuel line. Glenn Lee
showed me the best fuel line I have ever used: Dynamite’s Lighting
Line fuel tubing. It grips fittings better than any tubing I have seen. It is
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Tom Brown with his all-wood O.S. .65-powered D Speed model.
Charlie Legg’s beautiful home-built .049. Al Jones photo.
Glenn Lee’s hard tank system in his D Speed model. Notice the
rubber pads under the tank-mounting screws.
144 MODEL AVIATION
01sig5.QXD 10/27/03 8:46 am Page 144
January 2004 145
CST
The Composites Store Inc.
PO Box 622, Tehachapi, CA 93581
Order on-line or by phone
1-800-338-1278
Tech Support: 661-823-0108
• Rods & Tubes
• Carbon,
Aramid &
Fiberglass
Materials
• Epoxy
Systems
• Vacuum
Bagging and
Molding
Supplies
• FREE How-To
Articles on
the web
COMPOSITE MATERIALS
www.cstsales.com
STOCK THE
SHOP FOR
BUILDING
SEASON!
ULTRA BRITE LITES
NEW
NEED
MORE
INFO?
See your hobby retailer or send a #10 S.A.S.E. to
229 E. Rollins Rd. Round Lake Beach, IL 60073
847-740-8726 Fax 847-740-8727
www.RamRCandRamTrack.com
• W h i t e L E D ’ s
•Br i g h t e r • Tougher
• 5 X B a t t e r y L i f e
Flashing Navigation, (3) Lites,
Adj. rate, to 96”, 9V.......................RAM 121 $44.95
“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
distributed by Horizon Hobby, Inc.
(www.horizonhobby.com).
All of the joints will need to be wrapped to
hold everything together. A wide variety of
items, from tie wraps to wire, are used in this
area. I prefer 25-pound-test woven nylon
fishing line. The woven line is easy to work
with, doesn’t stretch when wet with fuel, and
does not have any sharp ends that might poke
holes in the tank during a run.
The next step is to install a cover that will
protect the bladder from the hot pan. There are
two items that can be used for this, one of
which is the woven-cotton finger-wrap
bandage that you can purchase at the local
drugstore. Cut off a 31⁄2-inch-long piece of
bandage, open it up, and slide it over the
Fisher tubing. Wrap the bandage material with
fishing line at the tee to keep it from sliding
off during use. Leave the other end open.
The other item used to protect the bladder
is a toy balloon. Cut the end off of the balloon,
then dip it in glycerin to lubricate it when it
slides over the outside of the tank.
The last, important step is to train the tank
to inflate from the front to the back. If you do
not do this, the tank will fill from back to front
and pinch the line off, resulting in no fuel and
no flight.
Take hold of the tank from the rear and
allow approximately 1⁄4 inch of the black
tubing to be free, and pinch the tubing off.
Inflate this 1⁄4 inch with air from your empty
fuel syringe. After doing this, the bladder will
01sig5.QXD 10/27/03 8:46 am Page 145
146 MODEL AVIATION
always fill from the front to the back. A
bladder constructed as described will easily
hold 45 cubic centimeters of fuel for a
Formula 40 or less for the .21 events.
One interesting thing a bladder fuel
system will do is let you know if you had the
proper set on your flight. This will happen on
the last lap of your flight. If you have the
ideal set on the valve, the engine will go
slightly rich as the pressure rises slightly in
the bladder, as it forces the last bit of fuel out.
If the set is too lean, the engine will gain in
revolutions just before it quits.
Let’s look at metal tanks. In a hard-tank
system, the fill lines are plugged off and fuel
is forced to the spray bar with crankcase
pressure. Many erratic engine runs are caused
by too large of a hole in the pressure nipple
that is installed in the backplate or backplate
bolt holes. The recommended-size hole for a
pressure fitting is .015 inch, but that is quite
small and many find it hard to make a fitting
that little.
The easiest method I have found for
making a hole this size is to drill a 1⁄32-inch
hole through the pressure fitting, then use soft
solder to close the end of the hole. However,
before you do that, insert a piece of .015
control line a short way into the fitting. Screw
the fitting into a small waste block of steel or
use a C-clamp to hold the fitting. Grab the
loose wire in the drill chuck of your drill
press or clamp the wire to something so that
the block is roughly 1⁄2 inch in the air.
Turn your soldering iron on and let it heat up.
When it is hot, touch it to the wire near the
pressure fitting. This will heat the wire and
just melt the solder in the fitting, letting it
drop off of the wire. You end up with a
fitting that has a clean, small hole in it.
You should install a fuel-check valve in
the pressure line to the tank. This will allow
the tank to be filled without flooding the
engine by forcing fuel through the pressure
fitting.
When I first started flying Speed a few
years ago, I used metal tanks in everything.
During this time I often commented that I did
not need tin-plate stock to build my tanks; I
just carved my tanks from a solid block of
solder.
It seemed that after just a few flights there
would be a leak. It was to the point that I took
a glass jar and water to every contest to leaktest
my tank. I also carried a butane-powered
soldering iron. It was soon pointed out to me
that the reason for all of the leaks was that I
had improperly mounted the metal tank in the
model. I had built the tank so that it would be
pinched between the top and the pan, which
allowed it to vibrate and crack.
I built a new tank and tried the simple
method of embedding it in a few rows of
silicone caulk. This helped tremendously, and
my speeds picked up as a result. The
problems I encountered with this method
were two-fold. First, the caulk would slowly
degrade from fuel and need to be picked out
and replaced. Second, if a leak did occur, the
tank would need to be dug out of the caulk
bed, cleaned, soldered, and reset. This is a
messy, slow process at best.
The next improvement was to vertically
Tell them you saw it in
“Modeler’s Mall”
This month we list those who
have donated $10 or more in support
of the Academy’s programs, the
National Model Aviation Museum and
the Aeromodeling Center. These
people have made more than a
donation—they have made an
investment in the future of
aeromodeling.
When you see these folks, thank
them! They are now among the
thousands who have given back to
model aviation part of what model
aviation has given to them. Many
things will be possible due to the their
thoughtful giving and generosity.
We list our supporters monthly.
These donations represent amounts
processed in the month of
September 2003. If your name is not
listed, please write to the
Membership Department and include
a canceled check. We want to
recognize all contributors!
Thank you.
$100 up to $500
Sue Barrett - CT
Ronald D Dailey - IN
C Ted Patrolia - MA
William K Sewell - CA
Joe Andrasik - OH
El Paso Radio Controllers - TX
William J Fialkowitz - FL
Jeffrey E Gagne - AZ
Lucian Garda - NY
Kit Gerhart - IN
David W Jones - IL
David J Mathewson - NY
Norman M Mclam - FL
C C Phelan - IL
Allan K Scidmore - WI
Mark E Sexton - IN
Earl J Sidmore - IL
David C Thomas - OH
Jack Thorne - OH
Fred L Wettengel - OK
$10 up to $100
Your Contributions do Make a Difference!
Did You Know …
That any donation you make to AMA is taxdeductible?
AMA is a 501(c)(3), not-for-profit association.
This means that any funds you donate beyond
your regular membership dues can be deducted
from your taxes.
Please consider donating to AMA. Your gift will
help us continue our efforts to improve your
organization.
01sig5.QXD 10/27/03 8:46 am Page 146
solder a piece of 1⁄4-inch tubing that was
roughly 3⁄8-inch long on each end of the tank.
The end of this tubing is flush with the
bottom of the tank. Then the pan is marked
for the center of the tubes and is drilled and
tapped. I inserted fuel tubing in the tubing
and left it long enough to extend
approximately 1⁄8 inch past the bottom and
top of the tube. I installed a screw with a
washer through the tubing and tightened it.
This causes the tubing to expand and holds
the tank.
This technique does a great job of
dampening vibration. It works well on the
smaller tanks, but in tanks for a D Speed
model it is better to solder three or four feet
to the tank and place rubber strips between
them and the tank.
Metal tanks are popular in the 1⁄2A Proto
event. Many are installed so that the feed
tube in the tank is 1⁄4 to 1⁄2 inch past the
centerline of the spray bar in the venturi
when viewed from the top. This layout will
cause the valve setting to change as the fuel
is used. If you view the tank from the top or
bottom of the model, the feed tube should be
in line or no more than 1⁄16 inch past the
centerline of the spray bar. This setup will
provide an even feed of fuel throughout the
run. If you need more fuel, make the tank
longer or taller—never wider.
I am out of space for now. I will write more
about this in the future. I’ll be back in three
months. MA
Edition: Model Aviation - 2004/01
Page Numbers: 144,145,146,148
Edition: Model Aviation - 2004/01
Page Numbers: 144,145,146,148
IN THIS COLUMN I will write about fuel systems for Speed models.
At first glance it would seem that not many problems could occur with
these simple-looking systems, but improper fuel-delivery setups cause
many modelers to lose flight attempts, and they can also cause pilots to
turn poor times when they do make everything come together for a full
run.
This was made clear to me this spring while testing a new Formula
40 model. On the first lap the engine would burp just after takeoff; this
is not a good thing to have happen during the acceleration lap in this
event. My Speed partner Barry Tippett and I examined every part of
the fuel system, and everything looked fine. We flew it again and burp.
We then took my model and Barry’s model apart and compared
every part. The only difference we found was in the dump tube that I
had installed in the venturi. In desperation I soldered a piece of small
brass tubing with an inside diameter (ID) of .035 inch inside the tube.
We flew it again and no problem occurred.
The .125-inch ID tube I had used was large enough that when the
engine unloaded on takeoff, it would momentarily suck all of the fuel
from the tube and cause the burp. The smaller tube caused a slight
backpressure that stopped this from happening.
In the past many modelers used the black rubber bladders used in
ink pens as fuel tanks. They supplied the correct amount of pressure,
but their life spans left much to be desired. It was common for a
bladder to pop after as few as two flights, resulting in a lost attempt
and fuel sprayed all over the inside of the Speed model. They are much
better quality today.
Fisher Scientific offers black natural rubber latex tubing that
measures 1⁄8 x 1⁄32 inch. It will last a whole season without breaking; it
is excellent stuff. The part number is 14-150-5A, but before you order
be aware that Fisher requires a minimum order of 10 packages or 120
feet. This amounts to several lifetimes worth. You can purchase small
amounts of the tubing for a reasonable price from DARP Speed Pans
at (734) 266-7290.
To build a bladder tank you need a 21⁄4-inch-long chunk of the
Fisher tubing, a brass or nylon plug for the end, a Tee fitting to go
between the needle valve and the bladder, and fuel line. Glenn Lee
showed me the best fuel line I have ever used: Dynamite’s Lighting
Line fuel tubing. It grips fittings better than any tubing I have seen. It is
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Tom Brown with his all-wood O.S. .65-powered D Speed model.
Charlie Legg’s beautiful home-built .049. Al Jones photo.
Glenn Lee’s hard tank system in his D Speed model. Notice the
rubber pads under the tank-mounting screws.
144 MODEL AVIATION
01sig5.QXD 10/27/03 8:46 am Page 144
January 2004 145
CST
The Composites Store Inc.
PO Box 622, Tehachapi, CA 93581
Order on-line or by phone
1-800-338-1278
Tech Support: 661-823-0108
• Rods & Tubes
• Carbon,
Aramid &
Fiberglass
Materials
• Epoxy
Systems
• Vacuum
Bagging and
Molding
Supplies
• FREE How-To
Articles on
the web
COMPOSITE MATERIALS
www.cstsales.com
STOCK THE
SHOP FOR
BUILDING
SEASON!
ULTRA BRITE LITES
NEW
NEED
MORE
INFO?
See your hobby retailer or send a #10 S.A.S.E. to
229 E. Rollins Rd. Round Lake Beach, IL 60073
847-740-8726 Fax 847-740-8727
www.RamRCandRamTrack.com
• W h i t e L E D ’ s
•Br i g h t e r • Tougher
• 5 X B a t t e r y L i f e
Flashing Navigation, (3) Lites,
Adj. rate, to 96”, 9V.......................RAM 121 $44.95
“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
distributed by Horizon Hobby, Inc.
(www.horizonhobby.com).
All of the joints will need to be wrapped to
hold everything together. A wide variety of
items, from tie wraps to wire, are used in this
area. I prefer 25-pound-test woven nylon
fishing line. The woven line is easy to work
with, doesn’t stretch when wet with fuel, and
does not have any sharp ends that might poke
holes in the tank during a run.
The next step is to install a cover that will
protect the bladder from the hot pan. There are
two items that can be used for this, one of
which is the woven-cotton finger-wrap
bandage that you can purchase at the local
drugstore. Cut off a 31⁄2-inch-long piece of
bandage, open it up, and slide it over the
Fisher tubing. Wrap the bandage material with
fishing line at the tee to keep it from sliding
off during use. Leave the other end open.
The other item used to protect the bladder
is a toy balloon. Cut the end off of the balloon,
then dip it in glycerin to lubricate it when it
slides over the outside of the tank.
The last, important step is to train the tank
to inflate from the front to the back. If you do
not do this, the tank will fill from back to front
and pinch the line off, resulting in no fuel and
no flight.
Take hold of the tank from the rear and
allow approximately 1⁄4 inch of the black
tubing to be free, and pinch the tubing off.
Inflate this 1⁄4 inch with air from your empty
fuel syringe. After doing this, the bladder will
01sig5.QXD 10/27/03 8:46 am Page 145
146 MODEL AVIATION
always fill from the front to the back. A
bladder constructed as described will easily
hold 45 cubic centimeters of fuel for a
Formula 40 or less for the .21 events.
One interesting thing a bladder fuel
system will do is let you know if you had the
proper set on your flight. This will happen on
the last lap of your flight. If you have the
ideal set on the valve, the engine will go
slightly rich as the pressure rises slightly in
the bladder, as it forces the last bit of fuel out.
If the set is too lean, the engine will gain in
revolutions just before it quits.
Let’s look at metal tanks. In a hard-tank
system, the fill lines are plugged off and fuel
is forced to the spray bar with crankcase
pressure. Many erratic engine runs are caused
by too large of a hole in the pressure nipple
that is installed in the backplate or backplate
bolt holes. The recommended-size hole for a
pressure fitting is .015 inch, but that is quite
small and many find it hard to make a fitting
that little.
The easiest method I have found for
making a hole this size is to drill a 1⁄32-inch
hole through the pressure fitting, then use soft
solder to close the end of the hole. However,
before you do that, insert a piece of .015
control line a short way into the fitting. Screw
the fitting into a small waste block of steel or
use a C-clamp to hold the fitting. Grab the
loose wire in the drill chuck of your drill
press or clamp the wire to something so that
the block is roughly 1⁄2 inch in the air.
Turn your soldering iron on and let it heat up.
When it is hot, touch it to the wire near the
pressure fitting. This will heat the wire and
just melt the solder in the fitting, letting it
drop off of the wire. You end up with a
fitting that has a clean, small hole in it.
You should install a fuel-check valve in
the pressure line to the tank. This will allow
the tank to be filled without flooding the
engine by forcing fuel through the pressure
fitting.
When I first started flying Speed a few
years ago, I used metal tanks in everything.
During this time I often commented that I did
not need tin-plate stock to build my tanks; I
just carved my tanks from a solid block of
solder.
It seemed that after just a few flights there
would be a leak. It was to the point that I took
a glass jar and water to every contest to leaktest
my tank. I also carried a butane-powered
soldering iron. It was soon pointed out to me
that the reason for all of the leaks was that I
had improperly mounted the metal tank in the
model. I had built the tank so that it would be
pinched between the top and the pan, which
allowed it to vibrate and crack.
I built a new tank and tried the simple
method of embedding it in a few rows of
silicone caulk. This helped tremendously, and
my speeds picked up as a result. The
problems I encountered with this method
were two-fold. First, the caulk would slowly
degrade from fuel and need to be picked out
and replaced. Second, if a leak did occur, the
tank would need to be dug out of the caulk
bed, cleaned, soldered, and reset. This is a
messy, slow process at best.
The next improvement was to vertically
Tell them you saw it in
“Modeler’s Mall”
This month we list those who
have donated $10 or more in support
of the Academy’s programs, the
National Model Aviation Museum and
the Aeromodeling Center. These
people have made more than a
donation—they have made an
investment in the future of
aeromodeling.
When you see these folks, thank
them! They are now among the
thousands who have given back to
model aviation part of what model
aviation has given to them. Many
things will be possible due to the their
thoughtful giving and generosity.
We list our supporters monthly.
These donations represent amounts
processed in the month of
September 2003. If your name is not
listed, please write to the
Membership Department and include
a canceled check. We want to
recognize all contributors!
Thank you.
$100 up to $500
Sue Barrett - CT
Ronald D Dailey - IN
C Ted Patrolia - MA
William K Sewell - CA
Joe Andrasik - OH
El Paso Radio Controllers - TX
William J Fialkowitz - FL
Jeffrey E Gagne - AZ
Lucian Garda - NY
Kit Gerhart - IN
David W Jones - IL
David J Mathewson - NY
Norman M Mclam - FL
C C Phelan - IL
Allan K Scidmore - WI
Mark E Sexton - IN
Earl J Sidmore - IL
David C Thomas - OH
Jack Thorne - OH
Fred L Wettengel - OK
$10 up to $100
Your Contributions do Make a Difference!
Did You Know …
That any donation you make to AMA is taxdeductible?
AMA is a 501(c)(3), not-for-profit association.
This means that any funds you donate beyond
your regular membership dues can be deducted
from your taxes.
Please consider donating to AMA. Your gift will
help us continue our efforts to improve your
organization.
01sig5.QXD 10/27/03 8:46 am Page 146
solder a piece of 1⁄4-inch tubing that was
roughly 3⁄8-inch long on each end of the tank.
The end of this tubing is flush with the
bottom of the tank. Then the pan is marked
for the center of the tubes and is drilled and
tapped. I inserted fuel tubing in the tubing
and left it long enough to extend
approximately 1⁄8 inch past the bottom and
top of the tube. I installed a screw with a
washer through the tubing and tightened it.
This causes the tubing to expand and holds
the tank.
This technique does a great job of
dampening vibration. It works well on the
smaller tanks, but in tanks for a D Speed
model it is better to solder three or four feet
to the tank and place rubber strips between
them and the tank.
Metal tanks are popular in the 1⁄2A Proto
event. Many are installed so that the feed
tube in the tank is 1⁄4 to 1⁄2 inch past the
centerline of the spray bar in the venturi
when viewed from the top. This layout will
cause the valve setting to change as the fuel
is used. If you view the tank from the top or
bottom of the model, the feed tube should be
in line or no more than 1⁄16 inch past the
centerline of the spray bar. This setup will
provide an even feed of fuel throughout the
run. If you need more fuel, make the tank
longer or taller—never wider.
I am out of space for now. I will write more
about this in the future. I’ll be back in three
months. MA
Edition: Model Aviation - 2004/01
Page Numbers: 144,145,146,148
IN THIS COLUMN I will write about fuel systems for Speed models.
At first glance it would seem that not many problems could occur with
these simple-looking systems, but improper fuel-delivery setups cause
many modelers to lose flight attempts, and they can also cause pilots to
turn poor times when they do make everything come together for a full
run.
This was made clear to me this spring while testing a new Formula
40 model. On the first lap the engine would burp just after takeoff; this
is not a good thing to have happen during the acceleration lap in this
event. My Speed partner Barry Tippett and I examined every part of
the fuel system, and everything looked fine. We flew it again and burp.
We then took my model and Barry’s model apart and compared
every part. The only difference we found was in the dump tube that I
had installed in the venturi. In desperation I soldered a piece of small
brass tubing with an inside diameter (ID) of .035 inch inside the tube.
We flew it again and no problem occurred.
The .125-inch ID tube I had used was large enough that when the
engine unloaded on takeoff, it would momentarily suck all of the fuel
from the tube and cause the burp. The smaller tube caused a slight
backpressure that stopped this from happening.
In the past many modelers used the black rubber bladders used in
ink pens as fuel tanks. They supplied the correct amount of pressure,
but their life spans left much to be desired. It was common for a
bladder to pop after as few as two flights, resulting in a lost attempt
and fuel sprayed all over the inside of the Speed model. They are much
better quality today.
Fisher Scientific offers black natural rubber latex tubing that
measures 1⁄8 x 1⁄32 inch. It will last a whole season without breaking; it
is excellent stuff. The part number is 14-150-5A, but before you order
be aware that Fisher requires a minimum order of 10 packages or 120
feet. This amounts to several lifetimes worth. You can purchase small
amounts of the tubing for a reasonable price from DARP Speed Pans
at (734) 266-7290.
To build a bladder tank you need a 21⁄4-inch-long chunk of the
Fisher tubing, a brass or nylon plug for the end, a Tee fitting to go
between the needle valve and the bladder, and fuel line. Glenn Lee
showed me the best fuel line I have ever used: Dynamite’s Lighting
Line fuel tubing. It grips fittings better than any tubing I have seen. It is
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Tom Brown with his all-wood O.S. .65-powered D Speed model.
Charlie Legg’s beautiful home-built .049. Al Jones photo.
Glenn Lee’s hard tank system in his D Speed model. Notice the
rubber pads under the tank-mounting screws.
144 MODEL AVIATION
01sig5.QXD 10/27/03 8:46 am Page 144
January 2004 145
CST
The Composites Store Inc.
PO Box 622, Tehachapi, CA 93581
Order on-line or by phone
1-800-338-1278
Tech Support: 661-823-0108
• Rods & Tubes
• Carbon,
Aramid &
Fiberglass
Materials
• Epoxy
Systems
• Vacuum
Bagging and
Molding
Supplies
• FREE How-To
Articles on
the web
COMPOSITE MATERIALS
www.cstsales.com
STOCK THE
SHOP FOR
BUILDING
SEASON!
ULTRA BRITE LITES
NEW
NEED
MORE
INFO?
See your hobby retailer or send a #10 S.A.S.E. to
229 E. Rollins Rd. Round Lake Beach, IL 60073
847-740-8726 Fax 847-740-8727
www.RamRCandRamTrack.com
• W h i t e L E D ’ s
•Br i g h t e r • Tougher
• 5 X B a t t e r y L i f e
Flashing Navigation, (3) Lites,
Adj. rate, to 96”, 9V.......................RAM 121 $44.95
“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
distributed by Horizon Hobby, Inc.
(www.horizonhobby.com).
All of the joints will need to be wrapped to
hold everything together. A wide variety of
items, from tie wraps to wire, are used in this
area. I prefer 25-pound-test woven nylon
fishing line. The woven line is easy to work
with, doesn’t stretch when wet with fuel, and
does not have any sharp ends that might poke
holes in the tank during a run.
The next step is to install a cover that will
protect the bladder from the hot pan. There are
two items that can be used for this, one of
which is the woven-cotton finger-wrap
bandage that you can purchase at the local
drugstore. Cut off a 31⁄2-inch-long piece of
bandage, open it up, and slide it over the
Fisher tubing. Wrap the bandage material with
fishing line at the tee to keep it from sliding
off during use. Leave the other end open.
The other item used to protect the bladder
is a toy balloon. Cut the end off of the balloon,
then dip it in glycerin to lubricate it when it
slides over the outside of the tank.
The last, important step is to train the tank
to inflate from the front to the back. If you do
not do this, the tank will fill from back to front
and pinch the line off, resulting in no fuel and
no flight.
Take hold of the tank from the rear and
allow approximately 1⁄4 inch of the black
tubing to be free, and pinch the tubing off.
Inflate this 1⁄4 inch with air from your empty
fuel syringe. After doing this, the bladder will
01sig5.QXD 10/27/03 8:46 am Page 145
146 MODEL AVIATION
always fill from the front to the back. A
bladder constructed as described will easily
hold 45 cubic centimeters of fuel for a
Formula 40 or less for the .21 events.
One interesting thing a bladder fuel
system will do is let you know if you had the
proper set on your flight. This will happen on
the last lap of your flight. If you have the
ideal set on the valve, the engine will go
slightly rich as the pressure rises slightly in
the bladder, as it forces the last bit of fuel out.
If the set is too lean, the engine will gain in
revolutions just before it quits.
Let’s look at metal tanks. In a hard-tank
system, the fill lines are plugged off and fuel
is forced to the spray bar with crankcase
pressure. Many erratic engine runs are caused
by too large of a hole in the pressure nipple
that is installed in the backplate or backplate
bolt holes. The recommended-size hole for a
pressure fitting is .015 inch, but that is quite
small and many find it hard to make a fitting
that little.
The easiest method I have found for
making a hole this size is to drill a 1⁄32-inch
hole through the pressure fitting, then use soft
solder to close the end of the hole. However,
before you do that, insert a piece of .015
control line a short way into the fitting. Screw
the fitting into a small waste block of steel or
use a C-clamp to hold the fitting. Grab the
loose wire in the drill chuck of your drill
press or clamp the wire to something so that
the block is roughly 1⁄2 inch in the air.
Turn your soldering iron on and let it heat up.
When it is hot, touch it to the wire near the
pressure fitting. This will heat the wire and
just melt the solder in the fitting, letting it
drop off of the wire. You end up with a
fitting that has a clean, small hole in it.
You should install a fuel-check valve in
the pressure line to the tank. This will allow
the tank to be filled without flooding the
engine by forcing fuel through the pressure
fitting.
When I first started flying Speed a few
years ago, I used metal tanks in everything.
During this time I often commented that I did
not need tin-plate stock to build my tanks; I
just carved my tanks from a solid block of
solder.
It seemed that after just a few flights there
would be a leak. It was to the point that I took
a glass jar and water to every contest to leaktest
my tank. I also carried a butane-powered
soldering iron. It was soon pointed out to me
that the reason for all of the leaks was that I
had improperly mounted the metal tank in the
model. I had built the tank so that it would be
pinched between the top and the pan, which
allowed it to vibrate and crack.
I built a new tank and tried the simple
method of embedding it in a few rows of
silicone caulk. This helped tremendously, and
my speeds picked up as a result. The
problems I encountered with this method
were two-fold. First, the caulk would slowly
degrade from fuel and need to be picked out
and replaced. Second, if a leak did occur, the
tank would need to be dug out of the caulk
bed, cleaned, soldered, and reset. This is a
messy, slow process at best.
The next improvement was to vertically
Tell them you saw it in
“Modeler’s Mall”
This month we list those who
have donated $10 or more in support
of the Academy’s programs, the
National Model Aviation Museum and
the Aeromodeling Center. These
people have made more than a
donation—they have made an
investment in the future of
aeromodeling.
When you see these folks, thank
them! They are now among the
thousands who have given back to
model aviation part of what model
aviation has given to them. Many
things will be possible due to the their
thoughtful giving and generosity.
We list our supporters monthly.
These donations represent amounts
processed in the month of
September 2003. If your name is not
listed, please write to the
Membership Department and include
a canceled check. We want to
recognize all contributors!
Thank you.
$100 up to $500
Sue Barrett - CT
Ronald D Dailey - IN
C Ted Patrolia - MA
William K Sewell - CA
Joe Andrasik - OH
El Paso Radio Controllers - TX
William J Fialkowitz - FL
Jeffrey E Gagne - AZ
Lucian Garda - NY
Kit Gerhart - IN
David W Jones - IL
David J Mathewson - NY
Norman M Mclam - FL
C C Phelan - IL
Allan K Scidmore - WI
Mark E Sexton - IN
Earl J Sidmore - IL
David C Thomas - OH
Jack Thorne - OH
Fred L Wettengel - OK
$10 up to $100
Your Contributions do Make a Difference!
Did You Know …
That any donation you make to AMA is taxdeductible?
AMA is a 501(c)(3), not-for-profit association.
This means that any funds you donate beyond
your regular membership dues can be deducted
from your taxes.
Please consider donating to AMA. Your gift will
help us continue our efforts to improve your
organization.
01sig5.QXD 10/27/03 8:46 am Page 146
solder a piece of 1⁄4-inch tubing that was
roughly 3⁄8-inch long on each end of the tank.
The end of this tubing is flush with the
bottom of the tank. Then the pan is marked
for the center of the tubes and is drilled and
tapped. I inserted fuel tubing in the tubing
and left it long enough to extend
approximately 1⁄8 inch past the bottom and
top of the tube. I installed a screw with a
washer through the tubing and tightened it.
This causes the tubing to expand and holds
the tank.
This technique does a great job of
dampening vibration. It works well on the
smaller tanks, but in tanks for a D Speed
model it is better to solder three or four feet
to the tank and place rubber strips between
them and the tank.
Metal tanks are popular in the 1⁄2A Proto
event. Many are installed so that the feed
tube in the tank is 1⁄4 to 1⁄2 inch past the
centerline of the spray bar in the venturi
when viewed from the top. This layout will
cause the valve setting to change as the fuel
is used. If you view the tank from the top or
bottom of the model, the feed tube should be
in line or no more than 1⁄16 inch past the
centerline of the spray bar. This setup will
provide an even feed of fuel throughout the
run. If you need more fuel, make the tank
longer or taller—never wider.
I am out of space for now. I will write more
about this in the future. I’ll be back in three
months. MA
Edition: Model Aviation - 2004/01
Page Numbers: 144,145,146,148
IN THIS COLUMN I will write about fuel systems for Speed models.
At first glance it would seem that not many problems could occur with
these simple-looking systems, but improper fuel-delivery setups cause
many modelers to lose flight attempts, and they can also cause pilots to
turn poor times when they do make everything come together for a full
run.
This was made clear to me this spring while testing a new Formula
40 model. On the first lap the engine would burp just after takeoff; this
is not a good thing to have happen during the acceleration lap in this
event. My Speed partner Barry Tippett and I examined every part of
the fuel system, and everything looked fine. We flew it again and burp.
We then took my model and Barry’s model apart and compared
every part. The only difference we found was in the dump tube that I
had installed in the venturi. In desperation I soldered a piece of small
brass tubing with an inside diameter (ID) of .035 inch inside the tube.
We flew it again and no problem occurred.
The .125-inch ID tube I had used was large enough that when the
engine unloaded on takeoff, it would momentarily suck all of the fuel
from the tube and cause the burp. The smaller tube caused a slight
backpressure that stopped this from happening.
In the past many modelers used the black rubber bladders used in
ink pens as fuel tanks. They supplied the correct amount of pressure,
but their life spans left much to be desired. It was common for a
bladder to pop after as few as two flights, resulting in a lost attempt
and fuel sprayed all over the inside of the Speed model. They are much
better quality today.
Fisher Scientific offers black natural rubber latex tubing that
measures 1⁄8 x 1⁄32 inch. It will last a whole season without breaking; it
is excellent stuff. The part number is 14-150-5A, but before you order
be aware that Fisher requires a minimum order of 10 packages or 120
feet. This amounts to several lifetimes worth. You can purchase small
amounts of the tubing for a reasonable price from DARP Speed Pans
at (734) 266-7290.
To build a bladder tank you need a 21⁄4-inch-long chunk of the
Fisher tubing, a brass or nylon plug for the end, a Tee fitting to go
between the needle valve and the bladder, and fuel line. Glenn Lee
showed me the best fuel line I have ever used: Dynamite’s Lighting
Line fuel tubing. It grips fittings better than any tubing I have seen. It is
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Tom Brown with his all-wood O.S. .65-powered D Speed model.
Charlie Legg’s beautiful home-built .049. Al Jones photo.
Glenn Lee’s hard tank system in his D Speed model. Notice the
rubber pads under the tank-mounting screws.
144 MODEL AVIATION
01sig5.QXD 10/27/03 8:46 am Page 144
January 2004 145
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PO Box 622, Tehachapi, CA 93581
Order on-line or by phone
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“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
distributed by Horizon Hobby, Inc.
(www.horizonhobby.com).
All of the joints will need to be wrapped to
hold everything together. A wide variety of
items, from tie wraps to wire, are used in this
area. I prefer 25-pound-test woven nylon
fishing line. The woven line is easy to work
with, doesn’t stretch when wet with fuel, and
does not have any sharp ends that might poke
holes in the tank during a run.
The next step is to install a cover that will
protect the bladder from the hot pan. There are
two items that can be used for this, one of
which is the woven-cotton finger-wrap
bandage that you can purchase at the local
drugstore. Cut off a 31⁄2-inch-long piece of
bandage, open it up, and slide it over the
Fisher tubing. Wrap the bandage material with
fishing line at the tee to keep it from sliding
off during use. Leave the other end open.
The other item used to protect the bladder
is a toy balloon. Cut the end off of the balloon,
then dip it in glycerin to lubricate it when it
slides over the outside of the tank.
The last, important step is to train the tank
to inflate from the front to the back. If you do
not do this, the tank will fill from back to front
and pinch the line off, resulting in no fuel and
no flight.
Take hold of the tank from the rear and
allow approximately 1⁄4 inch of the black
tubing to be free, and pinch the tubing off.
Inflate this 1⁄4 inch with air from your empty
fuel syringe. After doing this, the bladder will
01sig5.QXD 10/27/03 8:46 am Page 145
146 MODEL AVIATION
always fill from the front to the back. A
bladder constructed as described will easily
hold 45 cubic centimeters of fuel for a
Formula 40 or less for the .21 events.
One interesting thing a bladder fuel
system will do is let you know if you had the
proper set on your flight. This will happen on
the last lap of your flight. If you have the
ideal set on the valve, the engine will go
slightly rich as the pressure rises slightly in
the bladder, as it forces the last bit of fuel out.
If the set is too lean, the engine will gain in
revolutions just before it quits.
Let’s look at metal tanks. In a hard-tank
system, the fill lines are plugged off and fuel
is forced to the spray bar with crankcase
pressure. Many erratic engine runs are caused
by too large of a hole in the pressure nipple
that is installed in the backplate or backplate
bolt holes. The recommended-size hole for a
pressure fitting is .015 inch, but that is quite
small and many find it hard to make a fitting
that little.
The easiest method I have found for
making a hole this size is to drill a 1⁄32-inch
hole through the pressure fitting, then use soft
solder to close the end of the hole. However,
before you do that, insert a piece of .015
control line a short way into the fitting. Screw
the fitting into a small waste block of steel or
use a C-clamp to hold the fitting. Grab the
loose wire in the drill chuck of your drill
press or clamp the wire to something so that
the block is roughly 1⁄2 inch in the air.
Turn your soldering iron on and let it heat up.
When it is hot, touch it to the wire near the
pressure fitting. This will heat the wire and
just melt the solder in the fitting, letting it
drop off of the wire. You end up with a
fitting that has a clean, small hole in it.
You should install a fuel-check valve in
the pressure line to the tank. This will allow
the tank to be filled without flooding the
engine by forcing fuel through the pressure
fitting.
When I first started flying Speed a few
years ago, I used metal tanks in everything.
During this time I often commented that I did
not need tin-plate stock to build my tanks; I
just carved my tanks from a solid block of
solder.
It seemed that after just a few flights there
would be a leak. It was to the point that I took
a glass jar and water to every contest to leaktest
my tank. I also carried a butane-powered
soldering iron. It was soon pointed out to me
that the reason for all of the leaks was that I
had improperly mounted the metal tank in the
model. I had built the tank so that it would be
pinched between the top and the pan, which
allowed it to vibrate and crack.
I built a new tank and tried the simple
method of embedding it in a few rows of
silicone caulk. This helped tremendously, and
my speeds picked up as a result. The
problems I encountered with this method
were two-fold. First, the caulk would slowly
degrade from fuel and need to be picked out
and replaced. Second, if a leak did occur, the
tank would need to be dug out of the caulk
bed, cleaned, soldered, and reset. This is a
messy, slow process at best.
The next improvement was to vertically
Tell them you saw it in
“Modeler’s Mall”
This month we list those who
have donated $10 or more in support
of the Academy’s programs, the
National Model Aviation Museum and
the Aeromodeling Center. These
people have made more than a
donation—they have made an
investment in the future of
aeromodeling.
When you see these folks, thank
them! They are now among the
thousands who have given back to
model aviation part of what model
aviation has given to them. Many
things will be possible due to the their
thoughtful giving and generosity.
We list our supporters monthly.
These donations represent amounts
processed in the month of
September 2003. If your name is not
listed, please write to the
Membership Department and include
a canceled check. We want to
recognize all contributors!
Thank you.
$100 up to $500
Sue Barrett - CT
Ronald D Dailey - IN
C Ted Patrolia - MA
William K Sewell - CA
Joe Andrasik - OH
El Paso Radio Controllers - TX
William J Fialkowitz - FL
Jeffrey E Gagne - AZ
Lucian Garda - NY
Kit Gerhart - IN
David W Jones - IL
David J Mathewson - NY
Norman M Mclam - FL
C C Phelan - IL
Allan K Scidmore - WI
Mark E Sexton - IN
Earl J Sidmore - IL
David C Thomas - OH
Jack Thorne - OH
Fred L Wettengel - OK
$10 up to $100
Your Contributions do Make a Difference!
Did You Know …
That any donation you make to AMA is taxdeductible?
AMA is a 501(c)(3), not-for-profit association.
This means that any funds you donate beyond
your regular membership dues can be deducted
from your taxes.
Please consider donating to AMA. Your gift will
help us continue our efforts to improve your
organization.
01sig5.QXD 10/27/03 8:46 am Page 146
solder a piece of 1⁄4-inch tubing that was
roughly 3⁄8-inch long on each end of the tank.
The end of this tubing is flush with the
bottom of the tank. Then the pan is marked
for the center of the tubes and is drilled and
tapped. I inserted fuel tubing in the tubing
and left it long enough to extend
approximately 1⁄8 inch past the bottom and
top of the tube. I installed a screw with a
washer through the tubing and tightened it.
This causes the tubing to expand and holds
the tank.
This technique does a great job of
dampening vibration. It works well on the
smaller tanks, but in tanks for a D Speed
model it is better to solder three or four feet
to the tank and place rubber strips between
them and the tank.
Metal tanks are popular in the 1⁄2A Proto
event. Many are installed so that the feed
tube in the tank is 1⁄4 to 1⁄2 inch past the
centerline of the spray bar in the venturi
when viewed from the top. This layout will
cause the valve setting to change as the fuel
is used. If you view the tank from the top or
bottom of the model, the feed tube should be
in line or no more than 1⁄16 inch past the
centerline of the spray bar. This setup will
provide an even feed of fuel throughout the
run. If you need more fuel, make the tank
longer or taller—never wider.
I am out of space for now. I will write more
about this in the future. I’ll be back in three
months. MA