Construction / tuning:

This little Mini Discus of Graupner is made out of Solidpor foam, which
is impact resistant. The shape was since the beginning fascinating for
me - like a real looking plane. After the Fox (Multiplex) this was my
second kids throw plane conversion. And here is how I have done it:
- first assemble the kids plane and throw it! If it flies well mark the
balancing point on the wings, if not you need to play around a bit until it
flies straight. Actually this plane sails better then the Fox!
- disassemble the plane.
- carve out the cockpit foam (leave min 5 mm of foam on all sides. Cut
with a scalpel or use a soldering pen to burn the foam away (but as
this stinks, I used the knife).
- elevator wing: the servo was connected with the elevator rudder
through a 1,2 mm steel push rod running in a tub on the outside of the
fuselage. The servo space I carved out in the nose and glued it in with
a hog glue gun. In order to avoid too much strain on the little servo I
build relay in the rudder fin by using a servo arm fixed with a screw. The
connection with the rudder is in the open as the distance is small. This
proved to be a simple and effective connection with the T-tail rudder!
- ailerons - when I found out that the used X-31 servos have the same
thinkness as the wing, I simply cut through the wings (the size of the
servos) and fixed them with white strong tape at the top & bottom. Also
this construction runs fine and gave until today (over a year now) no
problems! The ailerons are cut out 2,5 cm wide and the full length from
the fuselage to the wing-V point. The rudders were fixed on the upper
side to the wing with strong tape. The rudder horns are cut off servo
arms glued to the rudder with lots of super glue. The servo cables
where just long enough to be run until the cockpit of the plane - so
before you install your servos you may check this out. And, if you wish
to save more weight, just use one central servo. You need to be
creative to find space, but it is possible.
- the motor - a 13 g outrunner - was fixed to a 6 mm balsa wood fire
wall which I have sanded so that it fit just under the tip of the canopy.I
tried to leave enough foam around the motor to protect it.  On the 2 mm
shaft I fixed a Graupner mini-folding prop.
- The BEC and receiver I fixed in the cockpit area of the plane by carving
out lots of foam.
- Before you cut out the battery space, use double sided tape on the
bottom of the assembled plane and move the battery until you found
the point of balance. Then start cutting - in my case the battery space
was carved out under the main wing and a connection between the
battery compartment and the cockpit was drilled too.
NOTE: as i do not intend to fly 3 d with this plane I did not insert an
additional support rod into the wings as they seamed sturdy enough.
So far no issues!
:-) I know - the canopy fixing is rather poor (with a white O ring) however
I did not have magnets by the time of the conversion and until now
(over a year later) I "did not find the time" to fix the magnets! One day in
the future......
- Total time for conversion: approx. 4 hours

Flight Experience:

This little plane flies quick and quite fast. It does not like it slow as the
weight is pretty high for the profile used. However once it has speed it
glides like a big one. The reaction on the rudders, especially the
ailerons, is very direct.
Otherwise a fun plane and in my view the looks in the flight are great!
Site for radio controlled airplanes and more ...
MINI DISCUS RC (conversion)
  Foam (Solidpor)
650 mm
450 mm
approx 5,4 dm2
13 g / dm2 - RC conversion: 24 g / dm2
WEIGHT (producer):
85 g
125 g (including battery pack)
ELE C 10 1850 (Brushless, outrunner)
  1850 umin/V / 13 g /  3 A at 2 lipo
  4,6" x 2,3 " Graupner folding prop
Jeti Eco 12 A (12 g)
Futaba 2,4 GHz, 4 channel, 6004 (4,5 g)
Lipo Ray, 2 cells, 480 mA  
4 (2x ailerons, 1x elevator, 1x motor)
  wings: 2x robbe X-31 (4,5 g)
elevator: 1x eco 8  (8 g)
Intermediate - professional
All rights reserved by and its owner!
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