Madcow Rocketry Discovery User manual

Specications:
Length: 39.5”
Diameter 2.6”
Weight: 15oz
Recovery: 24” Nylon Chute
Motor Mount: 29mm
Fins: 3 - 1/8” Plywood
CG: 28” from nose tip
Recommended Motors:
Single Use RMS
F20J-4 950’ F40W-7 1170’
F50T-6 1050’ G64W-7 1620’
G40W-7 1440’
G80T-7 1410’
G77R-7 1400’
Parts List
1. (1) Molded nose cone
2. (1) Pre-slotted body tube
3. (1) Forward section body tube
4. (2) Centering rings
5. (1) Bulkhead
6. (1) Eyebolt, nut & washer
7. (1) 29mm motor tube
 8. (3)laser-cutns
9. (1) Kevlar® shock cord section
10. (1) Nylon shock cord section
 11. (1)9”x9”ameproofchuteprotector
12. (1) 24” Nylon chute
13. (2) ¼” launch lugs
14. (1) Coupler
Required to complete: 5 minute epoxy,
120/220sandpaper,maskingtape, nishing
ller/paint.
™
K-125
Discovery
898666 00125 3
®

2 ©2007 MadCow Rocketry™ Discovery™ Assembly
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teachpartbeforeassembly
–somemanufacturingtolerancesmayrequirelightsandingbeforenal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nishingandpainting.
Step 1 – Motor Mount Assembly
Testtthecenteringringsoverthemotormounttubeandsandifnecessary.Therings
shouldhaveasnugtbutlooseenoughtomovetheringoverthemotortubewithout
deformingit.Alsotesttthecenteringringsinthebodytubeandsandifnecessary.
One of the rings will have a notch for 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 notch) until there is approximately 1/8” of motor tube exposed.
IMPORTANT:Make sure you clean the
motor tube of any epoxy so as not to
interferewiththentangslater.
After the aft ring is dry, make a mark
2” from the other end of the motor
tube. Spread some epoxy on the
motor tube and slide the forward ring
(with the notch) until it aligns with the
mark.
Step 2 – Shock Cord Attachment
The shock cord in this kit consists of a shorter section of Kevlar and a longer section of
nylon cording. The two sections should be tied together using a single overhand, ring
bendordoublesherman’sknot.TheKevlarsectionwillbeattachedtothemotormount
and the nylon section will be attached to the nose cone.
Wrap the end of the Kevlar shock
cord around the forward end of the
motor tube and tie a square knot or
bowline knot near the notch in the
forward centering ring. Apply some
epoxy to the knot to make sure it
doesn’t come loose later. Make
sure the Kevlar loop is seated against the
forward centering ring so that it will not
interferewiththentangslater.YoucantackwithepoxyorCAtoholdinplace.
1/8” Exposed 2” Exposed
Forward Ring Notch
Fin Fin Tang
Apply CA or
Epoxy to knot
Push cord in corner and
tack with epoxy
Step 3 – 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.Makesurethecordpassesoverthenotchintheforwardcenteringring.Testtthe
motortubeassemblyintothebodytubetoensureasnugt.Sandthecenteringringsif
necessary.
Whenyouaresatisedwiththet,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! (The shock cord goes

Discovery™ Assembly ©2007 MadCow Rocketry™ 3
Ensureringsareclearofthenslots
Step 4 – Fin Assembly
Testteachofthensintotheprecutnslots.Thenshouldseatrmlyagainstthe
motortube-sandeachnifnecessary.Whenyouaresatisedwiththet,applysome
epoxytotheendofthentangthatwillcontactthemotortubeaswellasthenroot
that will contact the body tube. Also, spread a thin layer of epoxy on each side of the
ntang.Slidethenintoplaceandcheckthealignment.Continuerecheckingthen
alignment until you are sure the epoxy has set. Clean any excess epoxy from around the
njoint.Repeatfortheremainingns.Next,applyepoxylletstobothsidesofeachn.
Carefullysmooththeepoxylletswithyourngerbeforetheepoxysets.Alloweachllet
tosetbeforerotatingtheairframeforthenextllet.
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.
Step 6 – Forward Section Assembly
Insert the eyebolt through the hole in the center of the bulkhead and secure using the
washer and nut. IMPORTANT: Apply some epoxy to the nut and eyebolt threads
to ensure the nut doesn’t come loose later. Apply some epoxy to the inside of the
coupler and push the bulkhead in so there is about a 1/8” to ¼” of coupler exposed.
Aftertheepoxyhasset,applyalletofepoxyaroundtheinsideedgeofthecoupler
bulkheadjoint.
Next mark the coupler 2” from the forward edge. Apply some epoxy to the inside of the
forward body tube section and slide the coupler up to the mark. There should be 3”
of coupler exposed. Make sure the coupler is straight and the body tubes are aligned
properly when they are assembled later.
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tan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nsthatextendsfromthefrontto
the back of the body tube. This line will be used later to align the launch lugs.

24338 El Toro Rd #E-134
Laguna Woods, CA 92637
949.547.8847
www.madcowrocketry.com
©2006 MadCow Rocketry™
Step8–FlyingYourModel
Attachtheendoftheshockcordandtheparachutetothepayloadsectioneyebolt.You
canalsoattachthechuteprotectortotheshockcordjustbelowthat.Whenpacking
your chute, wrap the chute protector around the chute with the opening in the chute
protector facing forward. Always make sure your chute is well protected as the hot
ejectionmotorgasseswillmeltthenylonchute.
IMPORTANT: always use positive motor retention to secure the motor. Failure to
use motor retention will cause the motor to be ejected instead of the parachute
making for a dangerous ballistic reentry.
IMPORTANT: some motors do not have a thrust ring that rides against the back
of the motor tube. You can construct a thrust ring by wrapping a ¼” wide strip of
masking tape around the aft end of the motor until you have a layer of masking
tape approximately the same thickness of the motor tube. Do not y without a
thrust ring as the motor will y through the rocket causing a dangerously unstable
free ying rocket motor.
IMPORTANT: always remember to check your balance point and ensure your CG
is ahead of the specied CG point.
IMPORTANT: Always follow the NAR safety code and remember that rockets
are not toys and can be dangerous if not prepared and used properly. If you
are a beginner, it is a good idea to y with a club or other group of experienced
rocketeers until you have gained some experience.
IMPORTANT: In no event shall Madcow Rocketry be liable for any direct, indirect,
punitive, incidental, special consequential damages whatsoever arising out of
or connected with the use or misuse of it’s products. The buyer assumes all
risk and liability resulting from ANY use of any and all products sold by Madcow
Rocketry. Your purchase and use of any Madcow Rocketry product constitutes
your agreement to and acceptance of these terms. If you do not agree to these
terms and conditions, you must return the unused product in resalable condition
for a refund or credit.
IMPORTANT: Please contact us via phone or email if you have any questions about
constructing or ying your model.
Step 7 – Final Assembly
Insertthelargestmotoryouintendtoy(orsimulatetheweightwithansubstitute).
Ensure the CG is forward of the recommended CG. The CG is measured from the tip
ofthenosecone.IftheCGisbehindthespeciedpoint,addweightinsidethenose
cone by pouring lead shot into the nose cone tip and adding some epoxy. IMPORTANT:
Screw in a screw through the plastic nose cone into the lead to hold it in place.
Grind or cut off the screw head before lling and applying the nose cone nish.
The epoxy will not stick to the inside of the nose cone and if you do not anchor
with a screw, the liftoff force will cause the weight to become dislodged causing
an unstable model.Youcanalsoplacetheleadinthebaseofthenoseconesothatit
cannot become dislodged during liftoff, but you will have to use more weight.
®