Madcow Rocketry Batray User manual

Specications:
Length: 26”
Diameter 2.2”
Weight: 8oz
Recovery: 18” Nylon Chute
Motor Mount: 29mm
Features: Cut Lettering Vinyl Decal
Fins: 3 - 1/8” Plywood
CG: 17.75” from nose tip
Recommended Motors:
Single Use RMS
D12-5* 500’ E16W-7 950’
E9-4 * 790’ E23T-6 880’
E15-7* 1130’ F22J-7 1610’
F20W-7 1580’ F40W-7 1840’
*Requires 29/24 adaptor
Parts List
1. (1) Custom balsa nose cone
2. (1) pre-slotted body tube
3. (2) Centering rings
4. (1) 29mm motor tube
 5. (3)laser-cutns
6. (1) Kevlar® shock cord section
7. (1) Nylon shock cord section
 8. (1)6”x6”ameproofchuteprotector
9. (1) 18” Nylon chute
10. (2) ¼” launch lugs
11. (1) Cut Lettering Vinyl Decal
Required to complete: 5 minute epoxy,
120/220sandpaper,maskingtape, nishing
ller/paint.
K-118
898666 00118 5
Batray
tm

2 ©2007 MadCow Rocketry™ BATRAY™ 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

BATRAY™ 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.NOTE:ItisalsoagoodideatoCA
thesharptipsofthenstokeepthemfromsplinteringonhardlandings.
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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.
Step 6 – Nose Cone Assembly
At this point, pack the chute and assemble the rocket. Insert the largest motor that you
intendtoy(orsimulatetheweightwithanappropriatesubstitute)andensuretheCGis
forwardofthepointdenedinthespecicationsontherstpage.TheCGismeasured
fromthetipofthenosecone.IftheCGisbehindthespeciedpoint,addweightinside
noseconeuntiltheCGisforwardofthespeciedpoint.Youcanalsochoosetoya
lighter motor.
Whenyouaresatisedwiththebalanceofyourmodel,tiesomeknotsintheendofthe
nylon section of the shock cord and stuff the shock cord into the hole in the base of the
nose cone. Fill the hole with some epoxy to secure the shock cord.

24338 El Toro Rd #E-134
Laguna Woods, CA 92637
949.547.8847
www.madcowrocketry.com
©2006 MadCow Rocketry™
Step 7 – Flying Your Model
Attach the end of the shock cord and the parachute to the eyebolt of the nose cone. You
canalsoattachthechuteprotectortotheshockcordjustbelowthenosecone.
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.
Themotorretentionforyourmodelreliesonafrictiont.Ifthefrictiontistooloose
thenthemotorwillejectinsteadoftheparachutemakingforadangerousballistic
reentry.Youcanwrapmaskingtapearoundthemotortoadjustthefrictiont.Themotor
shouldbetightenoughthatitisdifculttoremove,butnotrequireenoughforcethatthe
model is destroyed.
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.
Atthispointyourmodelisreadytoy.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.
Now go have some fun!
Your model is now ready to paint and apply the decal. To apply the cut lettering decal,
carefully remove the backing from the decal - the individual letters will remain stuck
to the top carrier. Next, position the decal were you would like it and carefully smooth
out the top carrier to ensure the letters are securely attached to the rocket body. Last,
carefully remove the top carrier making sure the letters stay attached to the rocket body
and are not lifted with the carrier.