Kan Doo

This particular aircraft was built around 1986.  The plan used was published in April 1976 Aeromodeller (repeated in March 1985).  It appears that this plan differs from Peter Cock’s original, particularly with respect to the fuselage construction.  Click here to go to the plans page.

The overall weight of the model and its balance point will depend to a great extent on the construction of the fuselage.

This particular model uses a fuselage of ¼ inch balsa sandwiched between 1/32 inch plywood.  The overall weight is 514g, approximately 75g more than the weight quoted for the original.  As most of this extra weight is in the fuselage, the aircraft is very tail heavy.  It would only fly with the spinner of the ED Comp Special filled with lead, adding approx 60g to the overall weight.

This page shows the sequence of changing the nose of Kan Doo so that the aircraft would balance without extra lead ballast in the engine’s spinner.

Aircraft original specification
Wing chord 178 mm
Balance point for the Aircraft in flying trim

42 mm from leading edge
24% chord

Weight of ED Comp Special with ED 9 ½ x 7 airscrew 178 g
Weight of bare airframe 300 g
Weight of fuel tank 38 g
Weight of PAW 1.49 with 7 x 6 airscrew 118 g
ED Comp Special is mounted 133 mm ahead of the airframe C/G  
So PAW must be mounted 133 x 178/118 = 200 mm ahead of C/G This figure can be reduced to 185 mm when the weight of the extra mounting is taken into account.

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This is the aircraft in its original form having the balance point accurately determined in flying trim.  This was found to be 42mm from the leading edge and was used for all subsequent re-design calculations

  Click for enlarged image With the fuselage clamped into a "Workmate" the new engine bearers are fitted. The extension forward is about 35 mm.
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New balsa and ply built up around the extended engine bearers.


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And the wood is shaped to produce a shape in sympathy with the original lines.


  Click for enlarged image View of the overall "effect"
  Click for enlarged image Fuselage has been filled, smoothed and repainted.
  Click for enlarged image View of the overall effect.
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A new and slightly smaller fuel tank.  The pipes were silver soldered into the framework before the two parts were soft soldered together.  This makes the initial setting up of the parts a little harder but greatly simplifies the final soft soldering.  Click here to go to the plans page

The weight saving was 12 g.

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The extended engine mounting for the PAW 1.49.  The four "inboard" mounting holes fit the ED Comp Special so this engine can still be used for display flying but, due to its age, will not perform stunts.


  Click for enlarged image This is a revised exit for the elevator control rod.  Originally it was just pushed through the paper covering
  Click for enlarged image Airframe completed and the damage to the tissue covering on the wings caused by all the modifications has been patched up.
  Click for enlarged image General view of the nose of the aircraft with the new fuel tank mounted somewhat further forward than the original and nearer to the C of G.  No fuel tubing fitted as diesel tubing is difficult to find.
  Click for enlarged image Close up of the aircraft with the PAW 1.49 mounted.  Either this engine or the ED Comp Special will balance the aircraft in exactly the same point.