Sig Komander

What is there to say about the Sig Komander?  I guess it came on the scene around 1974, just after the Kadet Mk.1.  It was supposed to be an aileron trainer, whereas the Kadet was 3 channel, but eventually had an aileron version as well.  Once the Kadet Mk.II came out with ailerons, the Komander was called an "Intermediate" trainer.  I remember in the early '90s, I had only been instructing for maybe 3 years or so and nobody wanted to teach a particular student with a Komander.  They all cautioned him that it really wasn't a trainer and he should try something slower.  He insisted and so I volunteered to be his instructor.  This airplane really grew on me and helped me to develop a flying technique and method of teaching that I have used ever since.  That student got his wings with only one minor landing incident ( the plane was back out the next day ).  That was the only Komander I have ever seen and unfortunately, it has now been discontinued and is an endangered species.  I'm on a mission to find a kit and document the design, so it may be re-created by anyone with an interest.  Claude McCullough really designed a great looking sport model, with unique but attractive lines and proportions.

So far, I've collected the instructions for the Mk.1 and Mk.II, as well as the partial plan for the Mk.II, which shows the full fuselage top view and the side view, only to the back of the wing.  There are some full size templates in the instruction booklet.  I have confirmed that the airfoil was a NACA 2414 with +0.5 deg incidence.  1 degree of washout was built into the foam cores ( the trailing edge was up 1/8" at the wingtip ).  The stabilizer was set to 0 incidence.  Dihedral is 2-1/4" under each wing tip ( approximately 4 degrees ).

For the Mk.1, the CG was 2" from the LE at the tip to start, moving back to about 2-1/2" for deliberate snap rolls and spins.  Recommended control movements were 1/2" for rudder, 3/8" for elevator and 1/8" to 3/16" for ailerons.

The Mk.2 was different, with a recommended CG of 1-3/4" to start, moving back to 2-1/4" for full aerobatics.  The control throws were recommended as 7/16" for elevator, 5/16" for aileron and 5/8" for rudder.

The main differences between the Mk.I and Mk.II were in the fuselage structure.  In the original model, the firewall was two pieces of 1/8" ply laminated together.  The fuselage top and bottom were 3/32" balsa ( also the sides? ).  In the Mk.II, the fuselage sides, top and bottom are 1/8" balsa, while forward fuselage bottom is 1/8" ply and the firewall is two pieces of 3/32" ply.  The forward fuselage is doubled inside with 1/8" ply, as opposed to 1/4" balsa in the Mk.I.  With the Mk.I, the wing was bolted on with either 1 or 2 dowels or rubber bands, while the Mk.II is bolted on with two forward dowel pins.  The Mk.II used easy hinges for the control surfaces, whereas the Mk.I used nylon ( poly hinges ).  The metal landing gear straps were replaced with nylon in the Mk.II.

Other details of the design include landing gear covers made from 0.030" plastic, 3/4" triangle stock to reinforce the firewall and tail surfaces ( fin and stab ) made from 1/4" balsa sheet.  The rudder has an 8.5 degree forward rake to it, with the hinge line measuring exactly 7-1/4".  The stabilizer spans 22" and is made up of two sheets glued together.  The forward sheet is tapered to a chord of 5-1/4" at the fuselage.  The elevator and rudder are made of 1/4" x 2" elevator/aileron stock.

The airplane was flown with a 0.40, 0.45 and 0.50 sized engines.  Anything greater than a 0.50, they recommended installing a spar in the foam wing.  The instructions show the installation of a Fox 0.45.  There was no right or down thrust built in.

Bill of Materials

Replacement foam wings from Eureka Aircraft ( part# W790 )
Cowl from Fiberglass Specialties ( part# SK-23 )
Canopy from Park Flyer Plastics

1/16 x 3 x 36 ( 14 ) balsa wing sheeting ( SIGB143 )
1/4 x 3/4 x 36 ( 2 ) balsa leading edge ( SIGB034 )
1/4 x 1/2 x 36 ( 2 ) balsa trailing edge ( SIGB033 )
1/4 x 1 x 36 ( 2 ) aileron stock ( SIGB441 )
1 x 1-1/4" x 8 ( 2 ) balsa block wing tips, available as 1" x 3" x 12" ( 1 ) block ( SIGB307 )
1/4 x 2" x 36" elevator and rudder ( SIGB443 )
1/8" x 12" x 12" lite ply hatch parts and fuselage bottom ( SIGPW064 )
3/32" x 12" x 12" plywood fuselage formers ( SIGPW010 )

3" main wheels ( 2 )
2-1/4" nose wheel ( 1 )
Nose Gear ( SIGSH603 )
3/8 x 3/4 x 6" ( 2 ) landing gear blocks, 5/32" groove ( SIGSH125 )
Landing gear retaining straps ( SIGSH131 )
2-1/4" spinner ( Goldberg )
Sullivan 10 oz RST fuel tank ( S428 )
Sig Poly Hinges ( SIGSH543 ) or Easy hinges ( SIGSH710 )
Strip Aileron Horn Set ( SIGSH594 )