April 2003 149
WE HAVE GONE quite awhile with no Speed column in Model
Aviation. During a conversation I had with Bob Hunt prior to the
Nationals this past summer, I inquired about the missing column. He
reached through the telephone and twisted my arm, and here I am! Let
me introduce myself.
I have built and flown model airplanes for a long time. Until
approximately five years ago, it was a Radio Control (RC) model in my
back yard. I spent much of the RC time with gliders. Then one day a
lifelong friend of mine—Barry Tippett—stopped by with a packet of
pictures he snapped at a Speed meet he had attended. I looked at the
pictures and asked many questions, then Barry slid a pan across the
table and said “Why don’t you build one?” I have been hooked ever
since.
Now, a few years later, I attend roughly five contests a year. I have
attended six Nationals and placed at five of them, with a second, two
thirds, a fourth, and a fifth. I have no records yet, so I still consider
myself a beginner in this most interesting part of the model-airplane
hobby. As a beginner, in future columns I will try to answer some of
the many questions that come up when a person builds his or her first
Speed model and flies it.
Now that the introduction is finished, let’s discuss B Speed. Several
years ago high nitromethane was the rule in this event. Nitro mixes
higher than 70% were needed to hit and exceed the 200-mile-per-hour
mark.
During these high-nitro days the SuperTigre X29 was the engine of
choice, and many improvements were made to get the engine to
produce the horsepower needed for 200 mph-plus flights. New pistons
had to be produced because the material in the Tigre pistons was too
soft. Extensive timing changes needed to be made to the cylinder liner
and disk rotor. New cylinder heads were needed to work with the nitro.
The models were of the conventional symmetrical design with
small changes to accommodate the tuned pipe. The nitro produced
enough power at the rich takeoff setting so that it was possible to set
the engine rich and launch the model, and when it transitioned to full
pipe there was enough fuel to do the job and not melt down if
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Glenn Lee (right) and pilot Bill Hughes hold Glenn’s recordsetting
B Speed model. He achieved a speed of 185.68 mph.
This is a right-side view of Glenn’s fuel system. Details in text.
The line on the left is the pipe pressure line to the takeoff tank.
Notice the two fuel lines going to the venturi.
04sig5.QXD 1.23.03 3:22 pm Page 149
everything was right. One lean run would
melt the top out of the piston; the high nitro
and tuned pipe were not forgiving at all to a
missed setting.
When the nitro content was reduced to
10%, speeds in this event plunged to the high
160s. The Tigre and other engines disliked
the low-nitro fuel. The new fuel did not
produce enough power at rich settings to get
the model off the ground. Speedsters tried
many approaches to overcome the fuel-feed
problems. Centrifugal switches that richened
the mixture after takeoff were used with
limited success. Pipe pressure with metal
tanks was difficult to set and inconsistent.
The engine supply for B Speed improved
greatly when Henry Nelson began producing
the Front Intake Rear Exhaust .29 that he
supplies with a tuned pipe designed for use
with low-nitro fuel. The engine uses the
same .750-inch-diameter crankshaft as the
Nelson .40. The crankcase is also the same
as the .40’s, except that the cylinder-liner
bore was reduced so that the cylinder would
not need to have very thick walls.
The piston cylinder set is of the AAC
(aluminum-aluminum chrome) configuration
and set up as shipped so tight that it is
difficult to turn them over slowly. This
combination on the low-nitro fuel is
forgiving to lean runs. The only drawback
mentioned is the long run time required to
break in the engine. This is best done in the
air and can be seen by speed increasing with
each flight.
Speed fliers who began working with the
Nelson on the test bench said that it
produced tremendous power on 10% nitro,
but the fuel-feed problems were worse with
this engine because of the massive intake.
A partial solution to the problem was
found by copying the models used in the
Fédération Aéronautique Internationale
(FAI) Speed events. The asymmetrical
design allowed for the exact placement of
the fuel tank required to provide fuel when
the engine was on the pipe. The takeoff
problems persisted.
150 MODEL AVIATION
✈
✈
✈
✈
✈
✈
✈
3952 S. Illinois Avenue ✈ Carbondale, IL 62901
866-881-0546-Phone
618-529-0006-Fax www.packliteoutdoorgear.com
1000 DuPont Denier Cordura Construction
PolarTec Fleece Lining
1/4 Inch Closed-Cell Foam Padding Throughout W/Divider Panel
All Cases Custom Made to Your Specs
Competive Pricing
Best Constructed Wing Products On The Market!
Zippered on 3 Sides
Former Speed columnist Glenn Lee has
overcome the fuel-feed problems. His model
of asymmetrical layout uses a fuel system
that allows lean high-power takeoffs along
with the exact setting needed when the
engine comes on the pipe.
Glenn’s solution was to build two tanks
in his model. The takeoff tank uses the space
in the backplate of the engine and extends
roughly 1⁄2 inch from the backplate. He
soldered a needle valve onto the back of this
small tank and ran a fuel line along the left
side of the engine to the venturi. This tank is
pressurized with pipe pressure. The main
and larger tank is placed and adjusted, as is
standard practice in FAI models.
This combination allows Glenn to set the
takeoff tank lean enough to develop all the
power needed to get the model airborne and
begin to build speed. Just as the takeoff tank
runs out of fuel, the speed is high enough
that the main tank is feeding the model as it
comes on the pipe.
Glenn’s best time this year was turned at
Detroit, Michigan, with a time of 185.68
mph for a record in this event. He said that
the engine is very tight and he expects
higher speeds when he finds the right
propeller.
Anyone interested in more information
about Control Line Speed should consider
joining the North American Speed Society,
or NASS. Write to NASS at Box 371,
Fenton MI 48430-0371.
That’s it for now. I’ll be back in three
months. Please send me any pictures or
requests for items you would like to see in
the column. If you’d like a reply, an SASE
would be appreciated. MA
Did You Know …
That any donation you make
to AMA is tax-deductible?
AMA is a 501(c)(3), not-forprofit
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.
04sig5.QXD 1.23.03 3:22 pm Page 150
Edition: Model Aviation - 2003/04
Page Numbers: 149,150
Edition: Model Aviation - 2003/04
Page Numbers: 149,150
April 2003 149
WE HAVE GONE quite awhile with no Speed column in Model
Aviation. During a conversation I had with Bob Hunt prior to the
Nationals this past summer, I inquired about the missing column. He
reached through the telephone and twisted my arm, and here I am! Let
me introduce myself.
I have built and flown model airplanes for a long time. Until
approximately five years ago, it was a Radio Control (RC) model in my
back yard. I spent much of the RC time with gliders. Then one day a
lifelong friend of mine—Barry Tippett—stopped by with a packet of
pictures he snapped at a Speed meet he had attended. I looked at the
pictures and asked many questions, then Barry slid a pan across the
table and said “Why don’t you build one?” I have been hooked ever
since.
Now, a few years later, I attend roughly five contests a year. I have
attended six Nationals and placed at five of them, with a second, two
thirds, a fourth, and a fifth. I have no records yet, so I still consider
myself a beginner in this most interesting part of the model-airplane
hobby. As a beginner, in future columns I will try to answer some of
the many questions that come up when a person builds his or her first
Speed model and flies it.
Now that the introduction is finished, let’s discuss B Speed. Several
years ago high nitromethane was the rule in this event. Nitro mixes
higher than 70% were needed to hit and exceed the 200-mile-per-hour
mark.
During these high-nitro days the SuperTigre X29 was the engine of
choice, and many improvements were made to get the engine to
produce the horsepower needed for 200 mph-plus flights. New pistons
had to be produced because the material in the Tigre pistons was too
soft. Extensive timing changes needed to be made to the cylinder liner
and disk rotor. New cylinder heads were needed to work with the nitro.
The models were of the conventional symmetrical design with
small changes to accommodate the tuned pipe. The nitro produced
enough power at the rich takeoff setting so that it was possible to set
the engine rich and launch the model, and when it transitioned to full
pipe there was enough fuel to do the job and not melt down if
CONTROL LINE SPEED
Dave Mark, Box 371, Fenton MI 48430; E-mail: [email protected]
Glenn Lee (right) and pilot Bill Hughes hold Glenn’s recordsetting
B Speed model. He achieved a speed of 185.68 mph.
This is a right-side view of Glenn’s fuel system. Details in text.
The line on the left is the pipe pressure line to the takeoff tank.
Notice the two fuel lines going to the venturi.
04sig5.QXD 1.23.03 3:22 pm Page 149
everything was right. One lean run would
melt the top out of the piston; the high nitro
and tuned pipe were not forgiving at all to a
missed setting.
When the nitro content was reduced to
10%, speeds in this event plunged to the high
160s. The Tigre and other engines disliked
the low-nitro fuel. The new fuel did not
produce enough power at rich settings to get
the model off the ground. Speedsters tried
many approaches to overcome the fuel-feed
problems. Centrifugal switches that richened
the mixture after takeoff were used with
limited success. Pipe pressure with metal
tanks was difficult to set and inconsistent.
The engine supply for B Speed improved
greatly when Henry Nelson began producing
the Front Intake Rear Exhaust .29 that he
supplies with a tuned pipe designed for use
with low-nitro fuel. The engine uses the
same .750-inch-diameter crankshaft as the
Nelson .40. The crankcase is also the same
as the .40’s, except that the cylinder-liner
bore was reduced so that the cylinder would
not need to have very thick walls.
The piston cylinder set is of the AAC
(aluminum-aluminum chrome) configuration
and set up as shipped so tight that it is
difficult to turn them over slowly. This
combination on the low-nitro fuel is
forgiving to lean runs. The only drawback
mentioned is the long run time required to
break in the engine. This is best done in the
air and can be seen by speed increasing with
each flight.
Speed fliers who began working with the
Nelson on the test bench said that it
produced tremendous power on 10% nitro,
but the fuel-feed problems were worse with
this engine because of the massive intake.
A partial solution to the problem was
found by copying the models used in the
Fédération Aéronautique Internationale
(FAI) Speed events. The asymmetrical
design allowed for the exact placement of
the fuel tank required to provide fuel when
the engine was on the pipe. The takeoff
problems persisted.
150 MODEL AVIATION
✈
✈
✈
✈
✈
✈
✈
3952 S. Illinois Avenue ✈ Carbondale, IL 62901
866-881-0546-Phone
618-529-0006-Fax www.packliteoutdoorgear.com
1000 DuPont Denier Cordura Construction
PolarTec Fleece Lining
1/4 Inch Closed-Cell Foam Padding Throughout W/Divider Panel
All Cases Custom Made to Your Specs
Competive Pricing
Best Constructed Wing Products On The Market!
Zippered on 3 Sides
Former Speed columnist Glenn Lee has
overcome the fuel-feed problems. His model
of asymmetrical layout uses a fuel system
that allows lean high-power takeoffs along
with the exact setting needed when the
engine comes on the pipe.
Glenn’s solution was to build two tanks
in his model. The takeoff tank uses the space
in the backplate of the engine and extends
roughly 1⁄2 inch from the backplate. He
soldered a needle valve onto the back of this
small tank and ran a fuel line along the left
side of the engine to the venturi. This tank is
pressurized with pipe pressure. The main
and larger tank is placed and adjusted, as is
standard practice in FAI models.
This combination allows Glenn to set the
takeoff tank lean enough to develop all the
power needed to get the model airborne and
begin to build speed. Just as the takeoff tank
runs out of fuel, the speed is high enough
that the main tank is feeding the model as it
comes on the pipe.
Glenn’s best time this year was turned at
Detroit, Michigan, with a time of 185.68
mph for a record in this event. He said that
the engine is very tight and he expects
higher speeds when he finds the right
propeller.
Anyone interested in more information
about Control Line Speed should consider
joining the North American Speed Society,
or NASS. Write to NASS at Box 371,
Fenton MI 48430-0371.
That’s it for now. I’ll be back in three
months. Please send me any pictures or
requests for items you would like to see in
the column. If you’d like a reply, an SASE
would be appreciated. MA
Did You Know …
That any donation you make
to AMA is tax-deductible?
AMA is a 501(c)(3), not-forprofit
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.
04sig5.QXD 1.23.03 3:22 pm Page 150