82 MODEL AVIATION
Red Scholefield | redscho@The Battery Clinic bellsouth.net
Also included in this column:
• AXi motor failure examined
• A friend of Lt. Col. Taplin
• Electrify Dynaflite’s Bird of
Time
• TME news
New source of A123 cells
A motor that overheats can develop
problems. This AXI shows abraded leads
caused by a stator that loosened.
The abused AXI (L) had clanking caused by a loose magnet. It was reglued, and the motor
works perfectly again. When machining sets the magnet spacing, they are less likely to
loosen.
The DeWALT 28-volt pack (item DC9280) is a new source of A123 cells for homemade
battery builders. Check out eBay for the best prices.
JERRY DITTMAR, a fellow electricpower
flier, has confirmed that the
DeWALT 28-volt NANO Lithium-Ion
battery pack (item DC9280) is built with
A123 cells. At eight per pack, they are a
great deal for those who can assemble their
own packs. If you purchase these cells on
eBay, they can cost as little as $7.50 each.
I am still waiting for reports of anyone
wearing out an A123 pack. The only
failures I have seen to date have been
attributed to crashes in which a cell was
physically damaged.
AXi Failure Analyzed: Andy Druga, a
fellow club member, noticed some strange
behavior as he powered up his Bird of Time
electric conversion. An AXI 2820/14 motor
seemed to chatter a bit on start, and then it
got worse; it would not start at all. The ESC
checked okay on another motor, so we
deduced that the power plant was the
culprit.
A teardown (not too difficult)—if you
remove the small C-clip on the shaft, the
whole armature will come out—revealed
that the armature was loose. That enabled it
to rotate a bit where it abraded the
insulation on one of the leads, allowing the
part to short to the motor frame.
Unsure if this was the problem, Andy
and I slid a heat-shrink sleeve over the lead
to insulate it. There was room to double up
with two pieces, for better insulation. We
added a drop or two of thin CA to freeze the
armature in place.
Then we noticed that the magnets
seemed out of line. We compared this with
the same part from an AXI 2808/24 that
was sacrificed earlier to the gravity gods.
The magnets in it had locating tabs molded
into the rotating part of the motor, while the
magnets in the 2820 were free to move
around if they became unglued.
We carefully realigned the magnets,
properly spacing them, added thin CA to
secure the magnets, and reassembled the
motor. Then we tested it to find that it ran
perfectly, drawing the same current with a
given propeller that it did originally. All is
well; the 2820/14 is back in service and
performing normally.
Electric Modeling History: In the
November 2009 column, I mentioned a “Col.
Taplin” as one of the pioneers of electricpowered
flight. Lynne Byrum sent me his
thoughts, which follow.
“I flew with Col (Lt. Col., actually) Taplin
when I was stationed at RAF Manston in
1957-58. He owned a shop called Birchington
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 82
March 2010 83
Left: Andy Druga and your author
like Great Planes’ Dynaflite Bird of
Time (BoT). The men were tired of
hi-start launches, so they modified
the models for electric power.
Right: A 1/4-inch-thick bulkhead is
fitted into the BoT ARF’s fiberglass
nose to suit an AXI 2820/14. Text
details correct placement and
thrust arrangement.
Below: The new E-BoT doesn’t
weigh much more than the stock
motorless version. (Motor and
battery replace large chunk of
ballast.) A 3S Li-Poly or 4S A123
spins the 13 x 7 folding propeller.
Engineering where he manufactured a neat .45
diesel in-line twin engine.
“Taplin had a background in full scale
aviation. I saw several electric models in his
hangar but never saw them fly.
“I think he used an Emerson windshield
wiper motor and large wet cell bats. The
airplane was the Radio Queen; a big cabin
model, rudder only. He also had a rudder-only
twin diesel with a cross-shaft between the
engines.
“Taplin was a friendly person with a good
sense of humor.”
Bird of Time Electrification: My mention of
the glider launcher shown with the Bird of
Time, in the November 2009 issue, brought
me more reader letters than any item before.
They were not about the launcher, but about
the model’s modification.
While I’m off of my battery/charger
discussions, Andy Druga and Richard Parker
came up with some information to aid anyone
who is interested in converting one of these
magnificent airplanes. Following is their
contribution.
Dynaflite’s Bird of Time, distributed by
Great Planes, is a beautiful sailplane that
embraces the style and grace of Thermicseries
sailplanes from the 1930s and 1940s.
This is shown on the cover of the vintage book
Model Glider Design, by Frank Zaic.
The Dynaflite Bird of Time ARF features a
fiberglass fuselage, and converting it to
electric power is easy. Start by removing the
ballast weight from the nose. Cut the nose off
of the fuselage, and modify the nose by
installing a bulkhead that will hold the motor.
The ballast consists of BBs epoxied into
the nose of the fuselage. A method to
remove the ballast is to drill a 3/8-inch hole in
the nose, and use a piece of hardwood dowel
and a light mallet to gently knock loose the
BBs.
An alternate method of removing the
ballast, if the BBs do not comfortably knock
out with the preceding method, is to cut the
fiberglass nose in sections, forward of the
intended cutoff line, with a fine-tooth razor
saw-type cutter. This will give you better
access to the epoxy/BB lump.
The final cut in the nose is approximately
1.5 inches back. When cutting off the nose,
angle the cut so that the thrust is down and to
the right.
We used approximately 1° to the right
and 2° down. It is unnecessary to be precise
here. Andy and I have slightly different
angles. You will probably find that any angle
up to approximately 3° right and 5° down
will work fine.
A 13 x 7 folding propeller works well
with this sailplane, so the exact amount
back-cut from the nose can be matched to
the typical 40mm spinner that is used so it
blends with the top of the fuselage. After
cutting, use sandpaper on a block to make
the cut into a smooth, flat plane. Final
cleanup of the area is done with a motor tool
and a drum sander.
To make the motor-mount bulkhead, hold
the fuselage nose down so that the cut is on a
piece of 1/4 model aircraft plywood. (Or hold
the plywood up to the nose.) Use a pencil to
trace the oval nose profile around the cut.
Cut out the bulkhead with a suitable
fixture or coping saw. Carefully smooth the
perimeter of the oval bulkhead using
sandpaper on a block, or a disk sander if
available. You may want to bevel the
perimeter approximately 5°, to match the
taper in the nose. Once you have finished
cutting and sanding, the bulkhead should fit
snugly inside the fuselage, exactly at the
cutline.
An AXI 2820/14 brushless outrunner or
equivalent provides adequate power and is
the motor on which this modification is
based. The 2820/14 is installed from inside
the aircraft, with the shaft protruding through
the bulkhead. It is best to locate the motor
mounting holes and motor-shaft clearance
before securing the bulkhead with epoxy.
Epoxy the bulkhead to the fuselage, so
that the front face of the bulkhead is flush
with the plane of the cut in the fuselage.
Since the front of the fuselage (now the
bulkhead) is oval, there is room for slight
vertical variation in the location of the
motor, and therefore the thrust centerline.
Andy’s thrust centerline is centered in the
oval, whereas Red’s is slightly higher, so
that the propeller hub fits the upper contour.
No apparent difference in the model’s
performance can be traced to this slight
difference in location.
A 3000-4200 mAh 3S Li-Poly or 4S
A123 battery provides adequate power and
flight time. You can install the battery in the
compartment under the canopy by lifting the
canopy.
To facilitate battery accommodation
under the canopy, we moved the rudder
servo to the compartment under the wing.
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 83
There is plenty of room in this section for
the servo, but you have to fashion
appropriate brackets to provide adequate
clearance.
The battery we used measures 4.5 inches
long and fits nicely. Its placement will
influence the Bird of Time's balance, so
place it accordingly. Positioned so that its
forward end is even with the forward canopy
bevel, the battery is in a convenient and
accessible location.
It is recommended to glue a battery stop
to the inside of the fuselage at this location,
to prevent the battery from shifting forward
while flying. You can also install a rear
battery stop.
We installed an optional main power
switch on the fuselage, approximately
midheight and 1.5 inches forward of the wing
LE. We used a 40- to 60-amp ESC, and it
will easily lay behind the AXI in the
fuselage.
With the motor and propeller installed,
the battery in place, and the aircraft
assembled to flying condition, perform final
balance per the instructions provided with the
kit. We found that a few adhesive-backed
lead weights (3 ounces) attached inside the
fuselage, just forward of the battery, worked
fine.
With this conversion, the Bird of Time
can be hand launched or launched rolling
along the ground, using a launch dolly, as
described on page 104 in the November MA.
The aircraft climbs rapidly and is still
light enough for enjoyable thermal soaring.
The sailplane in this column has had flights
that have been almost an hour long and
consumes roughly 1 Ah per hour, with no
lift.
We wonder how long it will be before
Dynaflite offers this great model already set
up for electric power.
TME Goes Direct: Tejera Microsystems
Engineering, which manufactures the high-
end Xtrema charge systems, has gone to
direct sale only and has drastically reduced
the price of its Xtrema Balancing Charger/
Wattmeter.
This unit comes complete with the USB
data cable, two Xtrema balancers, a Battery
Interface Module, and a temperature probe,
making a complete charging and analyzing
system for only $199.99 plus shipping and
handling.
Edition: Model Aviation - 2010/03
Page Numbers: 82,83,84
Edition: Model Aviation - 2010/03
Page Numbers: 82,83,84
82 MODEL AVIATION
Red Scholefield | redscho@The Battery Clinic bellsouth.net
Also included in this column:
• AXi motor failure examined
• A friend of Lt. Col. Taplin
• Electrify Dynaflite’s Bird of
Time
• TME news
New source of A123 cells
A motor that overheats can develop
problems. This AXI shows abraded leads
caused by a stator that loosened.
The abused AXI (L) had clanking caused by a loose magnet. It was reglued, and the motor
works perfectly again. When machining sets the magnet spacing, they are less likely to
loosen.
The DeWALT 28-volt pack (item DC9280) is a new source of A123 cells for homemade
battery builders. Check out eBay for the best prices.
JERRY DITTMAR, a fellow electricpower
flier, has confirmed that the
DeWALT 28-volt NANO Lithium-Ion
battery pack (item DC9280) is built with
A123 cells. At eight per pack, they are a
great deal for those who can assemble their
own packs. If you purchase these cells on
eBay, they can cost as little as $7.50 each.
I am still waiting for reports of anyone
wearing out an A123 pack. The only
failures I have seen to date have been
attributed to crashes in which a cell was
physically damaged.
AXi Failure Analyzed: Andy Druga, a
fellow club member, noticed some strange
behavior as he powered up his Bird of Time
electric conversion. An AXI 2820/14 motor
seemed to chatter a bit on start, and then it
got worse; it would not start at all. The ESC
checked okay on another motor, so we
deduced that the power plant was the
culprit.
A teardown (not too difficult)—if you
remove the small C-clip on the shaft, the
whole armature will come out—revealed
that the armature was loose. That enabled it
to rotate a bit where it abraded the
insulation on one of the leads, allowing the
part to short to the motor frame.
Unsure if this was the problem, Andy
and I slid a heat-shrink sleeve over the lead
to insulate it. There was room to double up
with two pieces, for better insulation. We
added a drop or two of thin CA to freeze the
armature in place.
Then we noticed that the magnets
seemed out of line. We compared this with
the same part from an AXI 2808/24 that
was sacrificed earlier to the gravity gods.
The magnets in it had locating tabs molded
into the rotating part of the motor, while the
magnets in the 2820 were free to move
around if they became unglued.
We carefully realigned the magnets,
properly spacing them, added thin CA to
secure the magnets, and reassembled the
motor. Then we tested it to find that it ran
perfectly, drawing the same current with a
given propeller that it did originally. All is
well; the 2820/14 is back in service and
performing normally.
Electric Modeling History: In the
November 2009 column, I mentioned a “Col.
Taplin” as one of the pioneers of electricpowered
flight. Lynne Byrum sent me his
thoughts, which follow.
“I flew with Col (Lt. Col., actually) Taplin
when I was stationed at RAF Manston in
1957-58. He owned a shop called Birchington
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 82
March 2010 83
Left: Andy Druga and your author
like Great Planes’ Dynaflite Bird of
Time (BoT). The men were tired of
hi-start launches, so they modified
the models for electric power.
Right: A 1/4-inch-thick bulkhead is
fitted into the BoT ARF’s fiberglass
nose to suit an AXI 2820/14. Text
details correct placement and
thrust arrangement.
Below: The new E-BoT doesn’t
weigh much more than the stock
motorless version. (Motor and
battery replace large chunk of
ballast.) A 3S Li-Poly or 4S A123
spins the 13 x 7 folding propeller.
Engineering where he manufactured a neat .45
diesel in-line twin engine.
“Taplin had a background in full scale
aviation. I saw several electric models in his
hangar but never saw them fly.
“I think he used an Emerson windshield
wiper motor and large wet cell bats. The
airplane was the Radio Queen; a big cabin
model, rudder only. He also had a rudder-only
twin diesel with a cross-shaft between the
engines.
“Taplin was a friendly person with a good
sense of humor.”
Bird of Time Electrification: My mention of
the glider launcher shown with the Bird of
Time, in the November 2009 issue, brought
me more reader letters than any item before.
They were not about the launcher, but about
the model’s modification.
While I’m off of my battery/charger
discussions, Andy Druga and Richard Parker
came up with some information to aid anyone
who is interested in converting one of these
magnificent airplanes. Following is their
contribution.
Dynaflite’s Bird of Time, distributed by
Great Planes, is a beautiful sailplane that
embraces the style and grace of Thermicseries
sailplanes from the 1930s and 1940s.
This is shown on the cover of the vintage book
Model Glider Design, by Frank Zaic.
The Dynaflite Bird of Time ARF features a
fiberglass fuselage, and converting it to
electric power is easy. Start by removing the
ballast weight from the nose. Cut the nose off
of the fuselage, and modify the nose by
installing a bulkhead that will hold the motor.
The ballast consists of BBs epoxied into
the nose of the fuselage. A method to
remove the ballast is to drill a 3/8-inch hole in
the nose, and use a piece of hardwood dowel
and a light mallet to gently knock loose the
BBs.
An alternate method of removing the
ballast, if the BBs do not comfortably knock
out with the preceding method, is to cut the
fiberglass nose in sections, forward of the
intended cutoff line, with a fine-tooth razor
saw-type cutter. This will give you better
access to the epoxy/BB lump.
The final cut in the nose is approximately
1.5 inches back. When cutting off the nose,
angle the cut so that the thrust is down and to
the right.
We used approximately 1° to the right
and 2° down. It is unnecessary to be precise
here. Andy and I have slightly different
angles. You will probably find that any angle
up to approximately 3° right and 5° down
will work fine.
A 13 x 7 folding propeller works well
with this sailplane, so the exact amount
back-cut from the nose can be matched to
the typical 40mm spinner that is used so it
blends with the top of the fuselage. After
cutting, use sandpaper on a block to make
the cut into a smooth, flat plane. Final
cleanup of the area is done with a motor tool
and a drum sander.
To make the motor-mount bulkhead, hold
the fuselage nose down so that the cut is on a
piece of 1/4 model aircraft plywood. (Or hold
the plywood up to the nose.) Use a pencil to
trace the oval nose profile around the cut.
Cut out the bulkhead with a suitable
fixture or coping saw. Carefully smooth the
perimeter of the oval bulkhead using
sandpaper on a block, or a disk sander if
available. You may want to bevel the
perimeter approximately 5°, to match the
taper in the nose. Once you have finished
cutting and sanding, the bulkhead should fit
snugly inside the fuselage, exactly at the
cutline.
An AXI 2820/14 brushless outrunner or
equivalent provides adequate power and is
the motor on which this modification is
based. The 2820/14 is installed from inside
the aircraft, with the shaft protruding through
the bulkhead. It is best to locate the motor
mounting holes and motor-shaft clearance
before securing the bulkhead with epoxy.
Epoxy the bulkhead to the fuselage, so
that the front face of the bulkhead is flush
with the plane of the cut in the fuselage.
Since the front of the fuselage (now the
bulkhead) is oval, there is room for slight
vertical variation in the location of the
motor, and therefore the thrust centerline.
Andy’s thrust centerline is centered in the
oval, whereas Red’s is slightly higher, so
that the propeller hub fits the upper contour.
No apparent difference in the model’s
performance can be traced to this slight
difference in location.
A 3000-4200 mAh 3S Li-Poly or 4S
A123 battery provides adequate power and
flight time. You can install the battery in the
compartment under the canopy by lifting the
canopy.
To facilitate battery accommodation
under the canopy, we moved the rudder
servo to the compartment under the wing.
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 83
There is plenty of room in this section for
the servo, but you have to fashion
appropriate brackets to provide adequate
clearance.
The battery we used measures 4.5 inches
long and fits nicely. Its placement will
influence the Bird of Time's balance, so
place it accordingly. Positioned so that its
forward end is even with the forward canopy
bevel, the battery is in a convenient and
accessible location.
It is recommended to glue a battery stop
to the inside of the fuselage at this location,
to prevent the battery from shifting forward
while flying. You can also install a rear
battery stop.
We installed an optional main power
switch on the fuselage, approximately
midheight and 1.5 inches forward of the wing
LE. We used a 40- to 60-amp ESC, and it
will easily lay behind the AXI in the
fuselage.
With the motor and propeller installed,
the battery in place, and the aircraft
assembled to flying condition, perform final
balance per the instructions provided with the
kit. We found that a few adhesive-backed
lead weights (3 ounces) attached inside the
fuselage, just forward of the battery, worked
fine.
With this conversion, the Bird of Time
can be hand launched or launched rolling
along the ground, using a launch dolly, as
described on page 104 in the November MA.
The aircraft climbs rapidly and is still
light enough for enjoyable thermal soaring.
The sailplane in this column has had flights
that have been almost an hour long and
consumes roughly 1 Ah per hour, with no
lift.
We wonder how long it will be before
Dynaflite offers this great model already set
up for electric power.
TME Goes Direct: Tejera Microsystems
Engineering, which manufactures the high-
end Xtrema charge systems, has gone to
direct sale only and has drastically reduced
the price of its Xtrema Balancing Charger/
Wattmeter.
This unit comes complete with the USB
data cable, two Xtrema balancers, a Battery
Interface Module, and a temperature probe,
making a complete charging and analyzing
system for only $199.99 plus shipping and
handling.
Edition: Model Aviation - 2010/03
Page Numbers: 82,83,84
82 MODEL AVIATION
Red Scholefield | redscho@The Battery Clinic bellsouth.net
Also included in this column:
• AXi motor failure examined
• A friend of Lt. Col. Taplin
• Electrify Dynaflite’s Bird of
Time
• TME news
New source of A123 cells
A motor that overheats can develop
problems. This AXI shows abraded leads
caused by a stator that loosened.
The abused AXI (L) had clanking caused by a loose magnet. It was reglued, and the motor
works perfectly again. When machining sets the magnet spacing, they are less likely to
loosen.
The DeWALT 28-volt pack (item DC9280) is a new source of A123 cells for homemade
battery builders. Check out eBay for the best prices.
JERRY DITTMAR, a fellow electricpower
flier, has confirmed that the
DeWALT 28-volt NANO Lithium-Ion
battery pack (item DC9280) is built with
A123 cells. At eight per pack, they are a
great deal for those who can assemble their
own packs. If you purchase these cells on
eBay, they can cost as little as $7.50 each.
I am still waiting for reports of anyone
wearing out an A123 pack. The only
failures I have seen to date have been
attributed to crashes in which a cell was
physically damaged.
AXi Failure Analyzed: Andy Druga, a
fellow club member, noticed some strange
behavior as he powered up his Bird of Time
electric conversion. An AXI 2820/14 motor
seemed to chatter a bit on start, and then it
got worse; it would not start at all. The ESC
checked okay on another motor, so we
deduced that the power plant was the
culprit.
A teardown (not too difficult)—if you
remove the small C-clip on the shaft, the
whole armature will come out—revealed
that the armature was loose. That enabled it
to rotate a bit where it abraded the
insulation on one of the leads, allowing the
part to short to the motor frame.
Unsure if this was the problem, Andy
and I slid a heat-shrink sleeve over the lead
to insulate it. There was room to double up
with two pieces, for better insulation. We
added a drop or two of thin CA to freeze the
armature in place.
Then we noticed that the magnets
seemed out of line. We compared this with
the same part from an AXI 2808/24 that
was sacrificed earlier to the gravity gods.
The magnets in it had locating tabs molded
into the rotating part of the motor, while the
magnets in the 2820 were free to move
around if they became unglued.
We carefully realigned the magnets,
properly spacing them, added thin CA to
secure the magnets, and reassembled the
motor. Then we tested it to find that it ran
perfectly, drawing the same current with a
given propeller that it did originally. All is
well; the 2820/14 is back in service and
performing normally.
Electric Modeling History: In the
November 2009 column, I mentioned a “Col.
Taplin” as one of the pioneers of electricpowered
flight. Lynne Byrum sent me his
thoughts, which follow.
“I flew with Col (Lt. Col., actually) Taplin
when I was stationed at RAF Manston in
1957-58. He owned a shop called Birchington
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 82
March 2010 83
Left: Andy Druga and your author
like Great Planes’ Dynaflite Bird of
Time (BoT). The men were tired of
hi-start launches, so they modified
the models for electric power.
Right: A 1/4-inch-thick bulkhead is
fitted into the BoT ARF’s fiberglass
nose to suit an AXI 2820/14. Text
details correct placement and
thrust arrangement.
Below: The new E-BoT doesn’t
weigh much more than the stock
motorless version. (Motor and
battery replace large chunk of
ballast.) A 3S Li-Poly or 4S A123
spins the 13 x 7 folding propeller.
Engineering where he manufactured a neat .45
diesel in-line twin engine.
“Taplin had a background in full scale
aviation. I saw several electric models in his
hangar but never saw them fly.
“I think he used an Emerson windshield
wiper motor and large wet cell bats. The
airplane was the Radio Queen; a big cabin
model, rudder only. He also had a rudder-only
twin diesel with a cross-shaft between the
engines.
“Taplin was a friendly person with a good
sense of humor.”
Bird of Time Electrification: My mention of
the glider launcher shown with the Bird of
Time, in the November 2009 issue, brought
me more reader letters than any item before.
They were not about the launcher, but about
the model’s modification.
While I’m off of my battery/charger
discussions, Andy Druga and Richard Parker
came up with some information to aid anyone
who is interested in converting one of these
magnificent airplanes. Following is their
contribution.
Dynaflite’s Bird of Time, distributed by
Great Planes, is a beautiful sailplane that
embraces the style and grace of Thermicseries
sailplanes from the 1930s and 1940s.
This is shown on the cover of the vintage book
Model Glider Design, by Frank Zaic.
The Dynaflite Bird of Time ARF features a
fiberglass fuselage, and converting it to
electric power is easy. Start by removing the
ballast weight from the nose. Cut the nose off
of the fuselage, and modify the nose by
installing a bulkhead that will hold the motor.
The ballast consists of BBs epoxied into
the nose of the fuselage. A method to
remove the ballast is to drill a 3/8-inch hole in
the nose, and use a piece of hardwood dowel
and a light mallet to gently knock loose the
BBs.
An alternate method of removing the
ballast, if the BBs do not comfortably knock
out with the preceding method, is to cut the
fiberglass nose in sections, forward of the
intended cutoff line, with a fine-tooth razor
saw-type cutter. This will give you better
access to the epoxy/BB lump.
The final cut in the nose is approximately
1.5 inches back. When cutting off the nose,
angle the cut so that the thrust is down and to
the right.
We used approximately 1° to the right
and 2° down. It is unnecessary to be precise
here. Andy and I have slightly different
angles. You will probably find that any angle
up to approximately 3° right and 5° down
will work fine.
A 13 x 7 folding propeller works well
with this sailplane, so the exact amount
back-cut from the nose can be matched to
the typical 40mm spinner that is used so it
blends with the top of the fuselage. After
cutting, use sandpaper on a block to make
the cut into a smooth, flat plane. Final
cleanup of the area is done with a motor tool
and a drum sander.
To make the motor-mount bulkhead, hold
the fuselage nose down so that the cut is on a
piece of 1/4 model aircraft plywood. (Or hold
the plywood up to the nose.) Use a pencil to
trace the oval nose profile around the cut.
Cut out the bulkhead with a suitable
fixture or coping saw. Carefully smooth the
perimeter of the oval bulkhead using
sandpaper on a block, or a disk sander if
available. You may want to bevel the
perimeter approximately 5°, to match the
taper in the nose. Once you have finished
cutting and sanding, the bulkhead should fit
snugly inside the fuselage, exactly at the
cutline.
An AXI 2820/14 brushless outrunner or
equivalent provides adequate power and is
the motor on which this modification is
based. The 2820/14 is installed from inside
the aircraft, with the shaft protruding through
the bulkhead. It is best to locate the motor
mounting holes and motor-shaft clearance
before securing the bulkhead with epoxy.
Epoxy the bulkhead to the fuselage, so
that the front face of the bulkhead is flush
with the plane of the cut in the fuselage.
Since the front of the fuselage (now the
bulkhead) is oval, there is room for slight
vertical variation in the location of the
motor, and therefore the thrust centerline.
Andy’s thrust centerline is centered in the
oval, whereas Red’s is slightly higher, so
that the propeller hub fits the upper contour.
No apparent difference in the model’s
performance can be traced to this slight
difference in location.
A 3000-4200 mAh 3S Li-Poly or 4S
A123 battery provides adequate power and
flight time. You can install the battery in the
compartment under the canopy by lifting the
canopy.
To facilitate battery accommodation
under the canopy, we moved the rudder
servo to the compartment under the wing.
03sig3.QXD_00MSTRPG.QXD 1/25/10 1:24 PM Page 83
There is plenty of room in this section for
the servo, but you have to fashion
appropriate brackets to provide adequate
clearance.
The battery we used measures 4.5 inches
long and fits nicely. Its placement will
influence the Bird of Time's balance, so
place it accordingly. Positioned so that its
forward end is even with the forward canopy
bevel, the battery is in a convenient and
accessible location.
It is recommended to glue a battery stop
to the inside of the fuselage at this location,
to prevent the battery from shifting forward
while flying. You can also install a rear
battery stop.
We installed an optional main power
switch on the fuselage, approximately
midheight and 1.5 inches forward of the wing
LE. We used a 40- to 60-amp ESC, and it
will easily lay behind the AXI in the
fuselage.
With the motor and propeller installed,
the battery in place, and the aircraft
assembled to flying condition, perform final
balance per the instructions provided with the
kit. We found that a few adhesive-backed
lead weights (3 ounces) attached inside the
fuselage, just forward of the battery, worked
fine.
With this conversion, the Bird of Time
can be hand launched or launched rolling
along the ground, using a launch dolly, as
described on page 104 in the November MA.
The aircraft climbs rapidly and is still
light enough for enjoyable thermal soaring.
The sailplane in this column has had flights
that have been almost an hour long and
consumes roughly 1 Ah per hour, with no
lift.
We wonder how long it will be before
Dynaflite offers this great model already set
up for electric power.
TME Goes Direct: Tejera Microsystems
Engineering, which manufactures the high-
end Xtrema charge systems, has gone to
direct sale only and has drastically reduced
the price of its Xtrema Balancing Charger/
Wattmeter.
This unit comes complete with the USB
data cable, two Xtrema balancers, a Battery
Interface Module, and a temperature probe,
making a complete charging and analyzing
system for only $199.99 plus shipping and
handling.
