Scratch MIM 23X Superhawk Original Design / Scratch Built

Scratch - MIM 23X Superhawk {Scratch}

Contributed by Andrew Bronfein

Manufacturer: Scratch
Style: Sport

This is quite an easy project compared to some of the rockets I have designed which will all be posted here.  It will be a nice start for the novice who wants to get into mid-power rocketry. Click  above image for full size pic. 

Parts List: 
1 2.6" Body Tube (I use Vaughn Brothers BT 2.6) 
2 Estes BT80a Nose Cones (Phoenix Style) 
1 10" section of BT-50 Body Tube 
1 Estes BT-80 Tube Coupler 
1 Estes Large Engine Mount Kit 
1 Estes Flat Centering Ring Kit 
1 1/8" Dowel 
1 Launch Lug (at least 3/8") 
1 48" x 4" sheet of 3/16" Balsa 
1 36" x 4" sheet of 1/8" Balsa 
30" of 1/2" shock cord 
1 good 24" parachute (your taste) 

Engines: At least an RMS 24mm F24.

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Step 1 
Cut the 2.6" body tube to 31.5" and cut the BT50 body tube to 10". Cut one of the NC80A nose cones 3" from the shoulder and then completely cut the bottom of the nose cone off, leaving as much of the shoulder as possible. Cut your fins to the dimensions in the plans.And lastly cut your wooden dowel to 30 3/4" and taper both ends at about a 75 degree angle. Round the leading edges of the all the fins and taper the trailing edges for better aerodynamics. The outer diameter of the Vaughn Brothers tube is a little bigger than the outer diameter of the nose cone and the boat tail so I just sand the outer tube at a shallow angle to give the feel of an even fit. You don't need to do this cause it is such a small difference that it really cant be seen, just felt if you run your finger over the seam. 

Step 2 
Out of the Engine Mount Kit, take the black engine block that fits into the 29mm engine mount and glue it 1/2 way into the engine mount. Glue the other half into the section of BT50 that you cut in step 1. Let dry. 

Step 3 
Mark your engine clip and cut the slot where the back of the engine clip will be placed and slide it in. From the Engine Mount Kit find the 2 green rings and cut 1/8" slots in then to allow them to slide over the engine hook. Glue them in place and let dry. 

Step 4 
In the Engine Mount Kit you will find 2 of the 4 necessary flat centering rings and the other two will come from the Centering Ring Set.  Glue your 1st centering right at the joint of the engine tube and the BT50 tube, measure up 1" and glue your 2nd centering ring. Glue your 3rd ring about 7" up the BT50 tobe from the 2nd ring and then the final ring about 2" up from the 3rd. Let dry for at least 4 hours. This will make a super sturdy engine mount. 

Step 5 
Using 20 minute epoxy, fasten the engine mount into the body tube pushing it only deep enough  that the shoulder of the boat tail (the NC80A Nose Cone that you cut) fits snugly to the rocket body.  Make absolutely sure that you make a solid enfine mount. This is probably the hardest step to this project. Let the epoxy fully set and strenghten the visible centering with another fillet of epoxy. Let the epoxy fully cure. 

Step 6 
Make an ejection gas baffle by tracing the INNER DIAMETER of the BT-80 Coupler onto some of your left over balsa from the fins, cut them out and then drill at least 12 1/4" holes in each peice. Epoxy the bottom peice into the coupler flush with one end let the epoxy harden then strenghten the inner side of the balsa with a fillet of epoxy. Repeat this step for the top of the baffle and strenghten the top of the balsa with a fillet of epoxy.  Let the epoxy fully cure then spread glue on the inner part of the body tube and push the entire baffle down the top of your body tube til it is 7" inside the tube. 

Step 7 
Use 5 minute epoxy to fasten the fins to your body tube. The fins should be 90 degrees apart and the top fins should directly in line with the bottom fins. Strenghten all joints with 20 20 minute epoxy. Let the epoxy fully cure then saturate the fins with CA. 

Step 8 
Using 5 minute epoxy center the dowel between two of the fins and the top and bottom of the  rocket's body tube.  Let cure, then apply 20 minute epoxy fillets.  Let cure then saturate the  exposed wood of the dowel with CA.  Epoxy the launch lug to the opposite side of the rocket's  body tube from where you fastened the dowel. 

Step 9 
Cut 30" of 1/2" thick shock cord material and fasten it into the body tube.  You can do this with your preferred method.  Choose a chute that matches your taste and mount it. 

Step 10 
Finish with Olive Drab Green or Flat White Krylon paint.  You can make decals by using a color printer and very thin paper, or use the more expensive route of designing your decals and then  having them printed to decal paper at a printer like Kinko's.  After decals are dry coat with  Krylon Matte Finish. Let dry completely. Launch. 

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