| Building an SSC Cobra, from a Pre-Production kit...thank you to designer Lee Liddle and wing manufacturer Roy Appleton, started Saturday March 27th, 2004 |
| Background: Lee Liddle designed the Falcon series in 2002, and refined them in 2003. For 2004 he incorporated changes to the design to make it more durable and retain the same simplicity of construction and "toughness" of design. I was fortunate to see the SSC Cobra and its big brother the Cobra S4 for Open B at the Paris, Texas Lone Star Championships. The SSC Cobra spans 64", whereas the Falcon uses elevons the Cobra uses an elevator and ailerons. Lee's reasoning for making this change was that if an aileron is hit on an elevon plane the plane is doomed and uncontrollable. He separated the controls to increase the survivability of the plane. Roy Appleton is offering the SSC Cobra as a complee kit, now. Go to www.texascombat.com and check out the kit section to order one.. This article was constructed using Roy's CNC cut cores and a lot of telephone time to make sure it was true to Lee's original design |
STEP #1
| The photos above show the results of step one. The middle photo shows the wood parts glued together and the right side picture shows how they will fit to the wing cores. The materials needed for Step #1 are: - Wing cores from Roy Appleton - 1/4" X 3" X 36" basswood for spars - 1/8" ply for spar doublers - 3/16" ply for motor mount support - 1-1/2" square poplar (found at Home Depot) for motor block - 4 #6 sheet metal screws 1" long. |
| Begin by making the spars. There is a left and right side. Use the wing cores to trace onto the 1/4" basswood the shape of the spar. A single 3" wide X 36" long basswood sheet is required to make one set of spars. Next cut two spar joiners for the center section of the wing. These are cut from 1/8" birch ply (not lite ply). Roy and Lee only use one spar doubler, but I used two. Please look closely at the spar joiners and notice they are beveled on each end. This is to prevent a stress point in the spar. 90 degree angles are stress points that break on impact. Also notice that the spar joiners are not the same size. The right side photo shows the spar trapped between the joiners and clamped in place while the glue sets. I used Pica Gluitt 2 It aliphatic glue for this step and let it dry overnight. |
| The noseblock and engine plate are made next. The engine plate is 3/16" birch ply (not lite ply). Roy uses a 6" plate, mine are 4-1/2" because I use a full size servo and heavier HDPE for the motor mount than he does. The motor plate is going to be attached to the noseblock with epoxy and #6 by 1" sheet metal screws. The noseblock is cut from 1-1/2" poplar. It really helps to have a bandsaw and belt sander to make this part. With these tools each noseblock can be made in five minutes. To make the noseblock take the EPP leading edge foam and trace the shape onto the wood. The right side photo shows the noseblock, and motor plate joined to the spar and set aside to dry. The next step will be adding the wing panels to the wood spar and nose assembly. |