April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]
Edition: Model Aviation - 2006/04
Page Numbers: 47,48,49,51,52,54
April 2006 47
by Leon Kincaid
RC Sailplaneto-
Electric-Power
Conversion
Perform this simple electric
conversion and leave the
launching winches at home!
THE HEAT SEEKER sailplane was
published in the May 1994 MA; the plans
are number 758. This design features a
fiberglass fuselage with a slip-on nose
cone and all-sheeted wings and tail
surfaces. It has a 122-inch wingspan with
ailerons and flaps or a polyhedral wing
with flaps. The fiberglass fuselage is
available from Bob Sealy of Quality
Fiberglass.
I had constructed five Heat Seekers and
ended up selling all of them, but I still had
one fuselage left. I had been contemplating
making a new, lighter RES [Rudder-
Elevator-Spoiler] Sailplane. Longtime
friend Vic Tyber suggested that I make it
an electric.
I began to think about it. A few days
later he gave me an AstroFlight FAI 15
motor with a planetary gearbox to use.
Then I had no choice!
I have records of every sailplane I
have constructed since 1972, of the
weights before and after covering, and of
the equipment used. The average weight
of my original Heat Seekers was 72
ounces.
If I still had one of the originals I
could remove the nose weight, the large
flight pack with the heavy standard-size
servos, the towhook, and the steel wing
rod. This would remove 18.6 ounces.
Adding the rather heavy AstroFlight
motor, small high-torque servos, ESC,
and a 24-gram carbon-fiber wing rod from
Aerospace Composite Products would add
15.8 ounces.
This would make one of my originals
69.2 ounces without a battery. This is
what you could plan on if you had an old,
retired Heat Seeker sitting in the corner of
your shop.
CONSTRUCTION
I had to start from scratch and build a
new sailplane that was lighter by using no
sheeting on the tail surfaces, less and
lighter sheeting on the wings with
capstrips over the ribs, spoilers with
microservos for each, and lighter covering
materials.
I called Kirk Massey of New Creations
R/C and told him about my plans to
convert a sailplane to electric power, the
wing area, my target weight of 70 ounces,
These techniques are
easy to adapt to other
sailplane designs you
want to convert
48 MODEL AVIATION
With a flexible metal ruler taped to the cone as a guide, make
the vertical cut using a single-edge razor blade and/or a sharp XActo
blade.
Notice the radius of the corners. Keep this in mind when
making the vertical cut, and don’t cut too deep!
Determine the spinner size needed. With the cone taped to the
fuselage, cut the nose off slightly smaller than required.
Epoxy the nose cone and bulkhead at the same time. The
bulkhead forces the fuselage round, and the template forces the
cone to be round.
Add the nose cone and mark the location of the horizontal cut.
The initial procedure is to level the edge of the radio access
area and then set the pen approximately 1/4 inch lower.
Photos courtesy the author
April 2006 49
With the fuselage level and the CG at 38%, the stabilizer should
be at 0°. The LE and TE should be the same height.
A simple battery tray was made from 1/16 balsa then carved and
sanded until it fit properly near the center of the fuselage under
the wing.
The standard, lighter, built-up wing with spoilers. The center
panels were covered with UltraCote #95x and the outer panels
were covered with thinner UltraCote Lite #96x.
The lighter tail section is ready for covering.
You can see the motor, the ESC, and the servos. The receiver is
mounted under the battery tray.
It looks as though Leon would rather be flying his electrified
Heat Seeker than posing for this photo!
Ni-Cd. He recommended a propeller size,
the amps and watts I would or should
read, and the angle at which the model
should climb. As it ended up, he was right
on.
After completion the Heat Seeker
weighed 68 ounces ready to fly with battery.
If you are starting from scratch, you can
save some time tapering the wing and
stabilizer ribs by using Anderson’s airfoil
program. Use airfoil K3311 for the wing and
NACA 65-A008 for the stabilizer. I
increased the stabilizer thickness 1%.
Cutting the nose off of most gliders and
adding a bulkhead to mount a motor is not
that big of a project, but a few new steps
must be taken with a slip-on nose cone. Start
by cutting a normal canopy cover on the
cone that is slightly larger than the existing
access area on the fuselage.
With the nose cone off, prop the fuselage
up over your building board until the edge
of the radio access area is level. Measure
down approximately 1/4 inch, add the nose
cone, and draw a horizontal line.
I did that by taping a felt-tip pin to a
height gauge to draw the line. You can also
measure up from the building board and
make two tick marks on the cone and then
draw the horizontal line. Do this to both
sides. This will represent the bottom of your
canopy cover.
With the cone off again, measure from
the small shoulder on the fuselage where the
edge of the cone would be to the back and
forward edge of the new canopy cover,
allowing at least 1/8-inch overlap in the rear
and approximately 3/16 inch in the front.
With the cone added, use these two
measurements to add to tick marks on the
top of the cone. With a felt-tip pin and a thin
metal or plastic scale on the tick marks,
wrap the scale half around the cone and
draw the rear and forward edges of the
canopy cover down to the horizontal lines.
Your new canopy cover is ready to cut
out. With a flexible metal scale taped to the
cone as a straightedge I used a single-edge
razor blade and a sharp X-Acto blade. I went
a little further on mine by making a thin
phenolic template and adding a radius to
each corner. It was much more work, but it
looks neat.
The next project is cutting the nose off.
Determine the spinner size needed, and,
with the cone taped to the fuselage, cut the
nose off slightly smaller than required. With
the nose off, the cone will probably go back
another 1/32-1/16 inch. Retape and prepare to
sand the nose for the correct spinner outside
diameter (OD) and right thrust and
downthrust.
With the Heat Seeker fuselage sitting on
a level building board and a level on top of
the fuselage tailboom, all measurements can
be made. With a future CG of 38%, the wing
will be roughly 11/2° positive incidence and
the stabilizer should be set at 0/0°.
With the nose sanded for a 40mm
spinner and a square against the nose, every
1/32-inch gap at the bottom of the nose
represents 1° of downthrust. For instance,
1/16 inch would be 2°, 3/32 inch would be 3°,
etc.
You can also use a combination set to
measure the angle of the downthrust. A
straightedge horizontally across the nose will
let you measure the side thrust. I used 2°
right thrust, which worked out perfectly.
I used only 2° downthrust, and it was not
enough. This causes me to hold more downelevator
in the climb than I should, but it is
not enough to bother changing.
The secret is to sand the nose the correct
OD and thrust angles at the same time. By
having the nose the correct angles, you can
add the motor-mounting bulkhead flush withthe nose and know that all thrust angles are
correct. However, the bulkhead must be
counterbored for the mounting screws to
clear the spinner.
You must do one thing before adding the
bulkhead. The fuselage and cone are made in
halves, and a ribbon that is approximately 1
inch wide covers each seam, top and bottom.
You must grind or sand this ribbon away
roughly 1/4 inch just inside of the cone and
the fuselage.
That allows the wall thickness to be the
same all the way around. A round bulkhead
will force the slightly egg-shaped fuselage to
be round too.
Because there is usually a small gap
between the fuselage and the cone, and since
the cone is slightly egg shaped, a thinplywood
template should be constructed with
a hole that is slightly larger than the spinner
OD. Force the template over the outside of
the cone during assembly to make the outside
round also.
I had added lugs to each side of my
template, with plans to pull it back tight on
the fuselage with rubber bands hooked to the
wing rod, but the template stuck so well on
the nose that I didn’t need them.
The cone and the bulkhead can be epoxied
together at the same time. Don’t overdo the
adhesive. I added epoxy around the rear of
the cone, the canopy area, on the bulkhead
during installation, and generously around the
nose between the fuselage and cone.
Last I added the plywood template on the
outside of the nose and clothespins around
the canopy area, using a Q-tip to wipe away
any excess epoxy that oozed out. This is
important to ensure that the canopy that was
previously cut out will be able to fit back in
its original position after everything dries.
The round bulkhead will force the fuselage to
be round, and the template will ensure that
the cone is round.
You have completed the hard part. Now
you need adequate ventilation and a battery
tray.
I left the hole, or opening, in the rear end
of the fuselage tailboom open. With the
rudder blocking the air exit I used my
Dremel hand tool, fitted with a small round
router bit, to scallop a bit on each side of the
rudder centerline to help the air exit.
I also drilled three 1/8-inch holes in or
under each wing fillet, and then I elongated
them with a small, round file to assist in
venting air. This position will not weaken the
fuselage and it is a good low-pressure area.
Since I am using a planetary gearbox and
a Turbo spinner with an air inlet in the
center, there is adequate space around the
mounting bulkhead to drill air-inlet holes
(which I did before installation). Had I used a
larger-OD gearless motor with a normal
spinner I would have had to add air inlets to
each side of the fuselage. I made a simple
battery tray from 1/16 balsa and carved and
sanded it to fit near the center of the fuselage
under the wing.
After fitting I added 1/8-inch cross-grain
balsa to support the battery weight and fit the
tray again. Last I added 1/8 square balsa near
the outside edge to guide the pushrods.
Once the tray was in place I installed the
battery by laying a thin-plywood Pizza
Paddle, measuring roughly 11/4 inches wide,
over the Velcro and sliding the battery in
over the paddle. Once the battery was in
place I pulled the paddle out. To remove the
battery I slide the paddle between the Velcro
to separate it, and the battery slides out.
Radio Installation: I used two small, strong
JR 341 servos for the rudder and elevator.
They are not only strong and light, but they
are nice and low, allowing me to install a
1700 mA stick-type battery over the top of
the servos to the battery tray. I used FMA
Direct S-80 servos in each wing for the
spoilers.
I installed a JES500 speed control. I was
going to use a small Hitec 555 receiver under
the battery box, but there was adequate room
for a full-size Futaba receiver with space for
foam between the two. I also used a Futaba
7UAF transmitter.
Flying: After installing the battery, the CG
was right on 38%. I have stopped trying to
hand-glide a model before flying it; that is a
good way to break something. I do my
trimming in the air, where it is safe.
On the first flight I let the model fly
straight ahead at half power for a second or
so, to make sure nothing was going wrong,and then I gave it full power. I couldn’t
believe the climb angle. I did have to hold
down-elevator in the climb, but as soon as
the power was cut, no change was needed in
the trims. The design has already proven to
be stable and effective.
The second flight lasted slightly longer
than an hour. For landing I had put the
spoilers on the landing-gear switch; the
Futaba flap knob is too difficult to find and
rotate. The quick action of the gear switch
does not seem to be a problem.
I am happy with the 16-ounce Ni-Cd, but
later I tried a Thunder Power three-cell, 2100
mA Li-Poly pack. The three-cell 2100 is the
minimum size to use with this motor, but I
don’t abuse it. I broke it in per the
instructions and it works super. Now my 68-
ounce Heat Seeker weighs 57 ounces! I am
thinking it would be even lighter with a
brushless motor and a smaller propeller …
In the meantime, Ray Gebaur converted
his 9-year-old Heat Seeker to electric power
with a new AstroFlight 05 motor. It flies
great (and weighs a ton). Vic Tyber says he is
going to convert his Heat Seeker to electric
as soon as I can cut his canopy out.
If you would like to start from scratch, Bob
Sealy still makes the fuselages for $55
including postage. I thought I would never
make or fly any Electrics larger than my
Speed 400- and GWS-powered old-time FF
designs, but this was a ball. MA
Leon Kincaid
[email protected]
Sources:
Aerospace Composite Products
357 Stealth Ct.
Livermore CA 94551
(800) 811-2009
www.acp-composites.com
Quality Fiberglass
Bob Sealy
2530 Zeb Warren Rd.
Cookeville TN 38501
(931) 526-4770
New Creations R/C
Box 496
Willis TX 77378
(935) 856-4630
www.newcreations-rc.com
Chuck Anderson
Box 305
Tullahoma TN 37388
(931) 455-6430
[email protected]