About this Plan
Bitsy. Control line speed model. For Torpedo .15 engine.
Quote: "Bitsy, International Speed Champion, by Bill Wisniewski. This noted speed designer whose 'Screamin' Demon' plans in AT led more than 50% of the country's control line speed flyers to use pen sac pressure tanks, now tackles the FAI records and encourages you to join in; rack up a new mark yourself!
There has been an increasing interest during the past year in international FAI modeling. With the K&B Torpedo .15 available, I decided to give the Federation's Class I catagory a try. To tell the truth I was amazed at the results. The first hop on the little job shown here was over 120 mph. The fastest to date has been 124 mph - considerably more than the record. I am waiting now for FAI speed trials around this part of the country (South-ern California).
I have used a number of new materials in this airplane; that is, they were new to me. I used glass fabric #120 to reinforce the entire airplane along with a polyester resin which is fuelproof. This is available through your hobby show from a number of concerns such as Berkeley and Midwest. Another new product utilized here is Epon Cement L-1372 (Specialty Resins, 2801 Lynwood Road, Lynwood, California) which was used to glue the metal wings together.
Before you start construction there are a few simple machining operations to be done to your K&B 15. Remove the cylinder and head from the engine and machine to 1 inch diameter. Remove the needle valve body, drill and tap through the venturi 10-32 and install a Dooling type needle valve and jet modified as shown.
Machine a spinner and back plate from dural. Make the hold-down fit-ting from a bicycle spoke and a piece of 1/32 steel. Solder this unit well as it holds the airplane together. Be sure to run your engine in before a contest or you will have trouble with freezing due to the close piston fit.
Construction is as follows: Start by selecting two pieces of white pine or hard balsa 3 x 1-1/2 x 12 in. Hold the blocks together by using wood screws driven about 1/2 in from the end. Turn on a wood lathe or carve to the contours shown on plans. Hollow the bottom to 3/32, leaving pads for mounting the engine and for dowels to locate top to pan. Cut the pan off as shown on the plans.
Have your local foundry cast an aluminum pan for you. Cost is about $1. Sand the top of the pan flat and mount the engine by drilling and tapping for 4-40 screws. Then hollow out the top shell to 3/32 wall thickness, leaving pads for locating dowels. Cup top to clear engine and tape the pan and top shell together. Drill 1/8 holes through the top and into the pan for the locating dowels. Glue the dowels in place while the top and pan are taped to-gether. Set aside to dry.
The spar is made from birch or some similar hardwood. Slot the spar for the bellcrank; be careful not to cut the slot too wide or it will weaken the spar..."
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