Sbach 300 30cc (yellow)

Power Considerations:

• Using 2 x 5S 5000 30C batteries, Rotomax 1.40-228kv motor and 20x10 APC prop there is an expectation of around 2700watts power available - see the eCalc results posted in a photo below.  The power to weight ratio of  585watts/kg allows for unlimited aerobatics.

Build Comments and Variations from the supplied equipment:

The radio system employed here is Spektrum.

Servos in General

• All recesses for servos accepted the HS-5495BHs without modification.
• The 5 Hitec HS-5495BH Karbonite geared servos, used all around, were found to have enough stall torque to cater for the loads expected. Only the aileron servo loading was calculated in detail.
• Pushrod connection is 17mm out at the servos and at least 35mm at the control surfaces. Mechanical advantage of 2. Rudder has a little less advantage.

Ailerons

• The smallest, reasonable gap was maintained between the aileron and wing trailing edge.
• Servos leads were found to be just long enough to get to the Servo Section Board (SSB) without extension.
• Ailerons are plugged into the Aile(right) and AUX1(left) channels (via the SSB of course). This allows for separate aileron setups.
• The wings and ailerons were very nice and straight out of the box. The supplied, rather thin, robart hinges were satisfactorily employed. They seem robust enough.
• The push rods supplied have a nice central winder for convenient length adjustment - left and right hand screw threads provide this versatility.
• The wing incidence varies from one wing to the other. Drilling out and relocation of the wing location spigots was required.

Stabiliser and Elevators:

• As supplied, out of the box, the stabiliser only needed nominal shimming to get it parallel with the main wing. Held in place using thin and medium CA.
• Servo lead extensions were soldered in. A convenient tube carries the leads to the SSB.
• The two servos are plugged into Elev(right) and Gear(left) channels providing separate Tx setup for each elevator half. The DX9 Tx allows for this in its Aircraft Type setting.

Rudder:

• The tail wheel assembly employs a torsion bar off the rudder to effect direction change. This ensures the rudder hinges never have to sustain impact loads.
• The rudder servo was mounted in the fuselage just behind the SSB and employs wires in a pull-pull arrangement. The wire connection to the end ball joiners is covered by shrink tube for neatness.
• The servo lead required no extension to reach the SSB.
  

Undercarriage:  (Bear in mind here that our local field has a grass runway......)

• The provided wheels were put into stock and replaced with 3.5 inch Dubro Low Bounce wheels. These reduce running noise whilst on the ground.
• Even these larger wheels fitted into the spats with minimal easing of the spat openings.
• Stub axles were used as supplied. Three spacers were needed to get the wheels to the centre of the spat openings.  The outer collars are nipped up finger tight against the wheel hubs and then tightenned in place. This prevents slapping of the wheels back and forward on their shafts.
• The undercarriage seems a little light on. Flight checks will confirm whether some stiffening laminations are required.

Front End:

• Cowel arrived cracked and not quite square! Two hidden and two exposed screws hold on the cowel. One of the fastening tongues had been dislodged.
• The motor mount box and firewalls seem very nicely fixed in place. The motor centering guides were accurately located.
• 4mm Threaded bar (with nuts and washers) was used to fasten the motor very firmly in place. Much tuning was required to get the spinner to sit nicely parallel to the cowel flange.
• The K-Force ESC was bolted to the inside top of the motor box.

Under the Canopy:

• Home made canopy latches were emplyed over the provided screws.
• Since the provided pilot figure was very out of scale, the inside of the canopy "glass" was spray painted with "Dusk Grey". This also minimised the poor quality of the moulded canopy plastic - much stretch opaqueness was evident in the surface. The paint job virtually removed this effect.
• A custom mounting bracket holds the XT90 arming switch firmly to the fuselage.
  
• All cables are custom cut and soldered in place. The harness includes serial connection for two batteries and power take-off, from one battery only, for the SBEC that powers the SSB, Rx and servos.
• The SBEC (regulator) converts the battery's nominal 18.5 volts down to 6 volts which is fed onto the SSB.
• The SSB is firmly screwed to the fuselage and manages power provision to the Rx (5.5v) and servos (6v). Plugging aileron servo leads onto the SSB is very comfortable since the SSB is very firmly located.
• The Rx mounts into the centre of the SSB and provides only signal/control to the servos. The Rx's two aerials feed through diverging plastic tubes mounted on the fuselage sides.
  
• The battery tray comprises perforated rubber mat epoxied to a custom shaped craft board which is, in turn, epoxied to the central fuselage tray structure.
• Two "Graphene" straps (440x20mm) are used to firmly locate the batteries very close to the joiner tube.

Overall Comments

Apart from some transportation damage to the canopy, cowel and fasteners, the plane was nicely manufactured. The film covering could have used a little more care. The decals went on quite satisfactorily.

Flight Review

As at 10-June-2017, not yet flown.....