Wilfred van Bergen
Jul 01, 1996, 01:00 AM
<html>
<head>
<title>The Simprop Diamond Electric Glider</title>
</head>
<body bgcolor="#FFFFFF">
<pre>It has already been a year since I bought and built this glider but I have
been flying it ever since. This may be a nice moment to look back at the
events that occured around this nice plane.
The DIAMOND is a glider in the 'near HOT-LINE' class. It promises a lot and
although it will not likely be found at the top, it will always be very close.
The kit comes in a huge box, since the wing is a single piece part,
prefabricated by Simprop to an incredible standard of perfection. It's a
white foam wing already covered with obechi and glass between them in
strategic places. The sheeting is only two pieces; one for the top and one
for the bottom, no seams. There is a slight double dihedral built in and the
ailerons are already cut out from the bottom and need only to be freed from
the sides. Tips are tilted slightly for some extra low speed stability.
The fuse is a nice white single piece of glass and epoxy. It does not need
any painting, since there are no seams at all and the finish itself is perfect.
The elevator is a single sheet of 5mm balsa, reinforced with an obechi
triangle where the bolt goes through to attach it to the tail.
The wing bolts on with two 5mm nylon bolts and a hardwood/brass dowel in the
LE. The holes and reinforcement for the bolts and the dowel are already in
place when you get the kit. A piece of ply in the fuse (also already
installed) is drilled and tapped to receive the wing bolts.
The instructions mention the cockpit canopy is to be screwed on with two small
screws, but I decided to use a regular BVM carbon latch lock.
Here is the data:
Wingspan : 1915mm
Length : 1063mm
Profile : RG14
Surface area : 32.12 / 36.43 dm^2 (wing / total)
Weight : 1750 - 2600 gram
Wingload : 48 - 71.4 gram/dm^2
The wide range of weight depends on the powersource you use and the number
of cells.
For powerplant I chose the Simprop powerspeed 7/14 motor. It's recommended
by Simprop and I must say that I was not disappointed. It's a relatively cheap
motor with a relatively agressive performance:
Voltage : 12V
Speed : 17600 RPM (no load)
Maximum current : 112A
Optimal current : 21A
Effeciency : 80%
Dimensions
Length : 89 / 71.7mm (with/without axis)
Diameter : 44.4mm
Axis Diam. : 5mm
Weight : 315 gram
The motor has cobalt magnets (neodymium) and is extremely powerful for it's
size and price.
This motor needs a rather strong ESC unit and I opted for the most powerfull
that Simprop had around at that time, the MOSFET P-90
Voltage : 9.6 - 36V (8-30 cells)
Cont. current : 60A
Max. current (5 sec) : 300A (!)
Weight : 75 gram
This ESC is produced in 4 layer sandwich construction and then wrapped with
some shrinkwrap to insulate it. The leads are 2.5mm^2 strong. The output is
directly soldered to the motor. The input leads are soldered to 4mm gold
plated connectors to accept the batteries. The control lead plugs into the
throttle channel of the receiver. It has NO BEC.
The RC equipment consists of a FUTABA mini PCM receiver which is located in
the tail boom of the plane. One servo for the elevator, located in the fin
and two servo's for the ailerons located in the wings.
After glassing the wing and stab with 25gm/m^2 and G-4 poly-urethane laquer
they are sprayed with acrylic from a can and some graphics are added, both
from the kit and some of own design.
The finished plane turned out to weigh near 2100 gram in full flight
configuration including a 12 cell 1800 mAh N-SCRC pack.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond1.jpg" width="283" height="196"> </pre>
</center></div>
<pre>Picture 1) shows the plane held by me for size reference. This was just
before another great flight. Remember to keep away from the propeller as
soon as the batteries are hooked up. It's a 9.5" x 5" aeronaut propeller
which folds back when the motor is not running. The ESC has a build in EMK
brake which snaps the motor to a halt which causes the propeller blades to
fold back. It turns out that this does not always work.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond2.jpg" width="301" height="230"> </pre>
</center></div>
<pre>Picture 2) shows the 'operations area' of the DIAMOND. One 12 cell battery
pack is in place, another is next to the cockpit for size reference. As you
can see the motor is rather small in comparison to it's performance.
Behind the motor is the receiver battery pack, followed by a former made of
sandwiched 'roof-mate', ply and glass cloth (own design).
The flightpack rests on this former with a U shaped bar. The bar is taped to
the pack and holds the entire pack in place. A small 'roof-mate' wedge is
pushed between the wing and the pack and this wedge makes it impossible for
the pack to move upward, which is the only way out.
The ESC is directly behind the former and below the flight pack. This setup
enables it to exchange packs through the cockpit very easily.
On the picture 2) you can also see the charger. It's the little black box in
the upper right corner. This charger is a computer charger made by Graupner
(Ultra Duo Plus) and hooks up to a 12V car battery. It's max output on
channel 1 is 4.3A which enable me to charge the flightpacks within 30
minutes. This charger can charge upto 30 cells (!) at once. Channel 2 is for
the receiver pack.
When charging flightpacks at the field I attach two clamps to the leads
which go to the car battery. At home, I take the clamps off and hook the
charger to a 13.8V/10A powersupply, generally used for CB equipment.
FLIGHT PROFILE.
The DIAMOND is a rather heavy glider, which implies that you have to speed
it up a bit to keep it airborne. The 7/14 motor is just perfect for that. It
takes of from your hand whith ease, but definitly needs close attention the
first 10 to 20 meters before it picks up speed. The motor pulls it away fast
and a 30 degrees ascend angle is easy to maintain. After about 30 seconds
the plane reaches a high enough altitude to stop the motor and start
soaring. As soon as the motor stops, the plane noses over and starts picking
up speed again. Once it has reached that speed it levels up and 'oh wonder',
it actually soars. It responds immediately to even the slightest of thermals
and I've managed to get flights of over 30 minutes from a single 30 second
motor boost. The plane is very friendly when I start to apply more up
elevator in order to slow it down a bit. For thermaling I keep the stick
back a bit all the time. The ailerons are drooped a bit to enhance the
airfoil slightly. At a certain point, the speed drops too low and the
DIAMOND tip stalls very sudden and very quickly. This happened to me once
close to the ground and there is no way out there. You have to fly this
plane fast at low altitudes.
The other end of the speed envelope is just as exciting. If there is no
thermal and you feel like doing some stunts, just go for it. From 300 meters
high, motor full throttle, nose down and off it goes. In one straight line
from 300 to 1 meters full speed down. No problem. Screaming by over the
field with it's propeller blades snapping and the immense howling of the
motor and the shreaking of the wind over the wings. Other pilots jump back
or look around nervous as they didn't here the plane come. This plane is
fast. Some up elevator and up it goes again with hardly any altitude loss.
More up results in a nice looping. Some aileron output and the plane turns
around it's axis to do a nice but not straight roll. If speed drops below
desired during a figure, just throttle up and the motor pulls you through.
Landing is a true problem with this plane. While touchy and tricky on slow
speeds and in turns, it nearly floats forever when on a straight course. The
ailerons are mixed as flaperons, and 50 degrees up ailerons make the plane
come down very quickly. Be advised to mix some down elevator to it or it
will nose-up, slow down and tip-stall nearly instantly. Once you get a hang
of this, it poses no big problems anymore.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond3.jpg" width="393" height="200"> </pre>
</center></div><div align="center"><center>
<pre> <img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond4.jpg" width="339" height="324"> </pre>
</center></div>
<pre>Pictures 3) and 4) show the DIAMOND in an earlier incarnation. It used to
have an 'inline' flight pack where the cells are soldered top to bottom.
This pack and the motor were ruined when it tipstalled on one of the earlier
flights and hit the deck. When I walked over to the plane, I forgot to
throttle down and the current kept flowing while the motor was blocked. 112A
* 14.4V = 'lots of heat and smoke' and the motor and pack had to be
replaced. At that point the plane got it's current paint scheme.
I hope you enjoyed this review. For remarks and questions and other
information you can E-mail me at: <a href="http://rcgroups.com/shared/nospam.php?u=bergen&d=mpn.cp.philips.com">bergen(at)mpn.cp.philips.com</a></pre>
</body>
</html>
<head>
<title>The Simprop Diamond Electric Glider</title>
</head>
<body bgcolor="#FFFFFF">
<pre>It has already been a year since I bought and built this glider but I have
been flying it ever since. This may be a nice moment to look back at the
events that occured around this nice plane.
The DIAMOND is a glider in the 'near HOT-LINE' class. It promises a lot and
although it will not likely be found at the top, it will always be very close.
The kit comes in a huge box, since the wing is a single piece part,
prefabricated by Simprop to an incredible standard of perfection. It's a
white foam wing already covered with obechi and glass between them in
strategic places. The sheeting is only two pieces; one for the top and one
for the bottom, no seams. There is a slight double dihedral built in and the
ailerons are already cut out from the bottom and need only to be freed from
the sides. Tips are tilted slightly for some extra low speed stability.
The fuse is a nice white single piece of glass and epoxy. It does not need
any painting, since there are no seams at all and the finish itself is perfect.
The elevator is a single sheet of 5mm balsa, reinforced with an obechi
triangle where the bolt goes through to attach it to the tail.
The wing bolts on with two 5mm nylon bolts and a hardwood/brass dowel in the
LE. The holes and reinforcement for the bolts and the dowel are already in
place when you get the kit. A piece of ply in the fuse (also already
installed) is drilled and tapped to receive the wing bolts.
The instructions mention the cockpit canopy is to be screwed on with two small
screws, but I decided to use a regular BVM carbon latch lock.
Here is the data:
Wingspan : 1915mm
Length : 1063mm
Profile : RG14
Surface area : 32.12 / 36.43 dm^2 (wing / total)
Weight : 1750 - 2600 gram
Wingload : 48 - 71.4 gram/dm^2
The wide range of weight depends on the powersource you use and the number
of cells.
For powerplant I chose the Simprop powerspeed 7/14 motor. It's recommended
by Simprop and I must say that I was not disappointed. It's a relatively cheap
motor with a relatively agressive performance:
Voltage : 12V
Speed : 17600 RPM (no load)
Maximum current : 112A
Optimal current : 21A
Effeciency : 80%
Dimensions
Length : 89 / 71.7mm (with/without axis)
Diameter : 44.4mm
Axis Diam. : 5mm
Weight : 315 gram
The motor has cobalt magnets (neodymium) and is extremely powerful for it's
size and price.
This motor needs a rather strong ESC unit and I opted for the most powerfull
that Simprop had around at that time, the MOSFET P-90
Voltage : 9.6 - 36V (8-30 cells)
Cont. current : 60A
Max. current (5 sec) : 300A (!)
Weight : 75 gram
This ESC is produced in 4 layer sandwich construction and then wrapped with
some shrinkwrap to insulate it. The leads are 2.5mm^2 strong. The output is
directly soldered to the motor. The input leads are soldered to 4mm gold
plated connectors to accept the batteries. The control lead plugs into the
throttle channel of the receiver. It has NO BEC.
The RC equipment consists of a FUTABA mini PCM receiver which is located in
the tail boom of the plane. One servo for the elevator, located in the fin
and two servo's for the ailerons located in the wings.
After glassing the wing and stab with 25gm/m^2 and G-4 poly-urethane laquer
they are sprayed with acrylic from a can and some graphics are added, both
from the kit and some of own design.
The finished plane turned out to weigh near 2100 gram in full flight
configuration including a 12 cell 1800 mAh N-SCRC pack.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond1.jpg" width="283" height="196"> </pre>
</center></div>
<pre>Picture 1) shows the plane held by me for size reference. This was just
before another great flight. Remember to keep away from the propeller as
soon as the batteries are hooked up. It's a 9.5" x 5" aeronaut propeller
which folds back when the motor is not running. The ESC has a build in EMK
brake which snaps the motor to a halt which causes the propeller blades to
fold back. It turns out that this does not always work.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond2.jpg" width="301" height="230"> </pre>
</center></div>
<pre>Picture 2) shows the 'operations area' of the DIAMOND. One 12 cell battery
pack is in place, another is next to the cockpit for size reference. As you
can see the motor is rather small in comparison to it's performance.
Behind the motor is the receiver battery pack, followed by a former made of
sandwiched 'roof-mate', ply and glass cloth (own design).
The flightpack rests on this former with a U shaped bar. The bar is taped to
the pack and holds the entire pack in place. A small 'roof-mate' wedge is
pushed between the wing and the pack and this wedge makes it impossible for
the pack to move upward, which is the only way out.
The ESC is directly behind the former and below the flight pack. This setup
enables it to exchange packs through the cockpit very easily.
On the picture 2) you can also see the charger. It's the little black box in
the upper right corner. This charger is a computer charger made by Graupner
(Ultra Duo Plus) and hooks up to a 12V car battery. It's max output on
channel 1 is 4.3A which enable me to charge the flightpacks within 30
minutes. This charger can charge upto 30 cells (!) at once. Channel 2 is for
the receiver pack.
When charging flightpacks at the field I attach two clamps to the leads
which go to the car battery. At home, I take the clamps off and hook the
charger to a 13.8V/10A powersupply, generally used for CB equipment.
FLIGHT PROFILE.
The DIAMOND is a rather heavy glider, which implies that you have to speed
it up a bit to keep it airborne. The 7/14 motor is just perfect for that. It
takes of from your hand whith ease, but definitly needs close attention the
first 10 to 20 meters before it picks up speed. The motor pulls it away fast
and a 30 degrees ascend angle is easy to maintain. After about 30 seconds
the plane reaches a high enough altitude to stop the motor and start
soaring. As soon as the motor stops, the plane noses over and starts picking
up speed again. Once it has reached that speed it levels up and 'oh wonder',
it actually soars. It responds immediately to even the slightest of thermals
and I've managed to get flights of over 30 minutes from a single 30 second
motor boost. The plane is very friendly when I start to apply more up
elevator in order to slow it down a bit. For thermaling I keep the stick
back a bit all the time. The ailerons are drooped a bit to enhance the
airfoil slightly. At a certain point, the speed drops too low and the
DIAMOND tip stalls very sudden and very quickly. This happened to me once
close to the ground and there is no way out there. You have to fly this
plane fast at low altitudes.
The other end of the speed envelope is just as exciting. If there is no
thermal and you feel like doing some stunts, just go for it. From 300 meters
high, motor full throttle, nose down and off it goes. In one straight line
from 300 to 1 meters full speed down. No problem. Screaming by over the
field with it's propeller blades snapping and the immense howling of the
motor and the shreaking of the wind over the wings. Other pilots jump back
or look around nervous as they didn't here the plane come. This plane is
fast. Some up elevator and up it goes again with hardly any altitude loss.
More up results in a nice looping. Some aileron output and the plane turns
around it's axis to do a nice but not straight roll. If speed drops below
desired during a figure, just throttle up and the motor pulls you through.
Landing is a true problem with this plane. While touchy and tricky on slow
speeds and in turns, it nearly floats forever when on a straight course. The
ailerons are mixed as flaperons, and 50 degrees up ailerons make the plane
come down very quickly. Be advised to mix some down elevator to it or it
will nose-up, slow down and tip-stall nearly instantly. Once you get a hang
of this, it poses no big problems anymore.</pre>
<div align="center"><center>
<pre><img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond3.jpg" width="393" height="200"> </pre>
</center></div><div align="center"><center>
<pre> <img src="http://static.rcgroups.com/articles/ezonemag/1996/../images/diamond4.jpg" width="339" height="324"> </pre>
</center></div>
<pre>Pictures 3) and 4) show the DIAMOND in an earlier incarnation. It used to
have an 'inline' flight pack where the cells are soldered top to bottom.
This pack and the motor were ruined when it tipstalled on one of the earlier
flights and hit the deck. When I walked over to the plane, I forgot to
throttle down and the current kept flowing while the motor was blocked. 112A
* 14.4V = 'lots of heat and smoke' and the motor and pack had to be
replaced. At that point the plane got it's current paint scheme.
I hope you enjoyed this review. For remarks and questions and other
information you can E-mail me at: <a href="http://rcgroups.com/shared/nospam.php?u=bergen&d=mpn.cp.philips.com">bergen(at)mpn.cp.philips.com</a></pre>
</body>
</html>