Scooter™ Assembly
©2007 MadCow Rocketry™
3
Ensure rings are clear of the fin slots
Step 4 – Fin Assembly
Test fit each of the fins into the pre cut fin slots. The fin should seat firmly against the
motor tube - sand each fin if necessary. When you are satisfied with the fit, apply some
epoxy to the end of the fin tang that will contact the motor tube as well as the fin root
that will contact the body tube. Also, spread a thin layer of epoxy on each side of the
fin tang. Slide the fin into place and check the alignment. Continue rechecking the fin
alignment until you are sure the epoxy has set. Clean any excess epoxy from around the
fin joint. Repeat for the remaining fins. Next, apply epoxy fillets to both sides of each fin.
Carefully smooth the epoxy fillets with your finger before the epoxy sets. Allow each fillet
to set before rotating the airframe for the next fillet.
Step 5 – Launch Lug Attachment
Mark the CG point along the launch lug line you made in the previous step. Make sure
you measure the CG point from the tip of the nose cone and NOT the end of the body
tube. Apply a small amount of epoxy on the launch lug line about ¾” long on the CG
mark. Press one of the launch lugs into the epoxy and ensure that it is aligned with the
launch lug line previously drawn on the body tube. You can site down the tube and look
through the launch lug to make sure it is straight. Similarly epoxy the second launch lug
about 1/2” from the aft end of the body tube. Site down both launch lugs and make sure
they are both aligned. If you have a ¼” launch rod, you can use this to ensure that both
lugs are aligned properly.
sure you have the motor assembly facing the right way! (The shock cord goes
over the forward centering ring)
Spread some more epoxy on the inside edge of the
body tube before sliding the rear centering ring into the body tube. Continue sliding the
assembly inside the body tube until the aft end of the motor tube is even with the aft end
of the body tube. It’s a good idea to
test fit a fin in each slot here before the
epoxy sets. Hold the body tube with
the motor tube assembly down until the
epoxy sets. Make sure the weight of
the motor assembly doesn’t cause it to
slide out of alignment.
Using a door jam or small section of angle stock, pencil a line halfway between two of
the fins that extends from the front to the back of the body tube. This line will be used
later to align the launch lugs.
Step 6 – Nose Cone Assembly
At this point, pack the chute and assemble the rocket. Insert the largest motor that you
intend to fly (or simulate the weight with an appropriate substitute) and ensure the CG is
forward of the point defined in the specifications on the first page. The CG is measured
from the tip of the nose cone. If the CG is behind the specified point, add weight inside
nose cone until the CG is forward of the specified point. You can also choose to fly a
lighter motor.
When you are satisfied with the balance of your model, screw the nut part way on the
eyebolt and stuff the eyebolt into the hole in the base of the nose cone. Fill the hole with
some epoxy to secure the eyebolt making sure the nut is covered by the epoxy and the
eye is exposed outside the epoxy. When the epoxy has set, secure the nylon end of the
shock cord to the eyebolt.
Your model is now ready to paint and apply the decals.
