2 ©2010
MadCow
Rocketry™
Squat™
Assembly
Squat™ Assembly
©2010 MadCow Rocketry™
3
Please make sure you read all directions and understand how to assemble your model
before you start construction. It is also a good idea to test fit each part before assembly
– some manufacturing tolerances may require light sanding before final assembly.
Laser cut parts will exhibit varying amounts of charring on the edges depending on the
density of the plywood. The charred edges do not interfere with bonding and do not
need to be cleaned before assembly. In most cases the charring will be cleaned up
during sanding for finishing and painting.
Step 1 – Motor Mount Assembly
Test fit the centering rings over the motor mount tube and sand if necessary. Also test fit
the centering rings in the body tube and sand if necessary. One of the rings will have a
hole for an eyebolt to attach the shock cord - this will be the forward ring. Spread some
epoxy on the outside of one end of the motor tube and slide the ring (without the hole)
until there is approximately 1/2” of motor tube exposed. Make sure you clean the motor
tube of any epoxy so as not to interfere with the fin tangs later. After the aft ring is dry,
make a mark 1/4” from the other end of the motor tube. Spread some epoxy on the
motor tube and slide the forward
ring until it aligns with the mark.
VERY IMPORTANT: make
sure there is not any epoxy
on the motor tube that would
interfere with the fin tangs
later on. Also make sure the
fin tangs will fit between the
two centering rings.
Mount the eyebolt using the nut
and washer in the forward ring
hole. Apply some epoxy to the
nut to ensure it will not come
loose later. Attach one end of
the shock cord to the eyebolt
using an overhand knot.
Step 3 – Fin Assembly
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 rail
buttons.
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 4 – Rail Button Attachment
Drill a 5/64” hole on the rail button line for the forward and aft rail buttons. These holes
should go into the centering rings. Apply a small amount of epoxy in the holes and
attach the rail buttons using the supplied #6 wood screws. Make sure the screw is loose
enough for the rail button to spin freely - this ensures the button is not compressed to the
point it will hang on the rail guide.
Step 2 – Insert Motor Tube Assembly into Body Tube
Wrap the shock chord into a small bundle and stuff it inside the motor tube for this next
step. Test fit the motor tube assembly into the body tube to ensure a snug fit. Sand the
centering rings if necessary.
When you are satisfied with the fit,
spread some epoxy on the inside of
the body tube and slide the forward
centering ring of the motor assembly
into the body tube.
Make sure you
have the motor assembly facing
the right way!
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.
Ensure centering rings are
clear of the fin slots
1/2” Exposed
1/4” Exposed
Forward Ring Hole
Fin
Fin Tang
Step 5 – Balancing Your Model
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 that the
CG is forward of the point defined in the specifications on the first page. The CG should
be measured from the tip of the nose cone. If the CG is behind the specified point,
add weight inside the nose cone by pouring lead shot into the nose cone and adding
some epoxy. Hold the nose cone with the tip down so the weight will be as far forward
as possible.
IMPORTANT: Screw in several screws through the plastic nose cone
into the lead to hold it in place. Grind or cut off the screw head before filling and
applying the nose cone finish. The epoxy will not stick to the inside of the nose
cone and if you do not anchor with screws, the liftoff force will cause the weight to
become dislodged causing an unstable model.
IMPORTANT: Proper CG is critical to the stability of this model.
This model will require some ballast in the nose - the amount will
depend on how you build and the size motor you use to fly. Do
not fly without balancing this model properly as a dangerous
unstable flight will result.
