CHK Cumulus "building"
Kit contents :
Fuselage :
Glass fiber , white gelcoat, push-pull Bowden type rods already installed for
rudder and elevator, elevator is the full flying stabilizer type, bellcrank is
already
installed
Wings:
4-piece wing, with flaps and ailerons, built-up construction, carbon reinforced
D-box, already covered with red transparent film, ailerons and flaps already
hinged, flaps are bottom-hinged.
Outer wing joiners : flat, vertical steel blade, and 2mm brass incidence pin.
Center wing joiner system : Floating type, 10mm carbon rod with 3 deg dihedral,
and 2 ea. 2mm brass incidence pins per wing
Rudder and elevators :
Built –up construction
forward fuselage canopy tailfeathers
inner panel outer panel hardware & accesories inner-outer panel joiner
The
“building”
The enclosed
“building instructions” are very sparse, apparently at CHK they figured that
somebody who buys this kind of sailplane, has done this before !
Anyway, you can’t really talk about “building” here, all that remains to be
done, is to install the servos in the wings and fuselage, and fabricate all the
connections and wiring.
Even so, it would have been nice to receive at least the figures for the control throws, I got these later from CHK per e-mail.
First order of
business was to cut the supplied servo wire to the required length, and pull it
into the wings, this is no big deal, since the wing panels come with
strings installed, which are used to pull the servo wiring through.
Next was to solder all the required connections, the connectors of the outer
wing joint are installed permanently in the respective root ribs, so that the
connection is established automatically, when plugging in the outer panels.
At the wing fuselage connection, the male part is fixed in the root rib, and the
female part of the connector is los in the fuselage, and has to be plugged in by
hand when assembling the plane.
Wing servo
installation
I used Hitec HS-85 MG servos for the flaps, and HS-81MG for the ailerons.
For the aileron servos I made these servo covers/mounts from some plywood, and
the supplied servo covers
servo bay servo cover/mount aileron servo aileron servo installed
Flap servos are installed in the servo well with mounting tape :
flapservo, HS-85MG flap servo cover flap linkage fairing
Drive system and RC components
installation
The electric drive
consists of a Kontronik drive 502 ( Kontronik FUN 500-27 motor with 5.2:1
gearbox ), aeronaut 17x11 folding prop, and 8 2400 mAh cells.
I later switched to an 18x11 prop.
The rest of the tasks was routine, the receiver battery pack and the speed controller are installed just aft of the motor, and the rudder and elevator servos aft of that,
and aft of that
the receiver ,a Hitec super slim 8 channel unit. Rudder and elevator
servos are Multiplex cockpit BB. By now this installation has been
changed, the elevator servo has been replaced with a Hitec HS-85 MG, and
relocated into the
tail. As you can see, there is not much room left in the fuselage, and
somewhere, I still had to fit my Skymelody vario !
I finally ended up securing it with Velcro to the canopy.
In order to balance the plane at the right CG location, the drive battery had to be pushed way back into the fuselage, for this I installed it in a piece of plywood,
which extends aft, and the is secured to another piece of plywood glued to the fuselage, the plywood tray is slotted, thus allowing fwd/aft movement, in order to
be able to fine-tune the CG location