Madcow Rocketry U.S. ARMY MIM-23B Hawk User manual

U.S. ARMY
MIM-23B Hawk
Specications:
Length: 36.25”
Diameter 2.6”
Weight: 21oz
Recovery: 24” Nylon Chute
Motor Mount: 29mm
Features: Balsa Boat Tail
Fins: 4 - 1/8” Plywood\
Scale: 1:5.4
CG: 22.5” from nose tip
Recommended Motors:
Single Use RMS
F20J-4 720’ F40W-7 1020’
F50T-6 975’ G33J-7 1330’
G38J-7 1250’ G64W-7 1740’
G40W-7 1390’
G80T-7 1470’
G77R-7 1450’
Parts List
1. (1) Molded nose cone
2. (1) Custom balsa tail cone
3. (1) pre-slotted body tube
4. (1) Centering ring
5. (1) 29mm motor tube
 6. (4)laser-cutns
7. (1) Kevlar® shock cord section
8. (1) Nylon shock cord section
 9. (1)9”x9”ameproofchuteprotector
10. (1) 24” Nylon chute
11. (2) ¼” launch lugs
12. (1) Cut Letter Vinyl decal
13. (1) 1/8” Spruce Tip Stock
Required to complete: 5 minute epoxy,
120/220sandpaper,maskingtape, nishing
ller/paint,leadshotfornoseweight.
K-116
898666 00116 1
®

2 ©2007 MadCow Rocketry™ MIM-23B Hawk 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tailconeintotheaftendofthebodytube.Makesurethatthetailcone
shoulderdoesnotinterferewiththenslot.Ifitdoes,sandtheshouldertothecorrect
length(thenominallengthoftheshouldershouldbe0.5”).Next,Testtthetailcone
and centering ring over the motor mount tube and sand if necessary. The centering ring
shouldhaveasnugtbutlooseenoughtomovetheringoverthemotortubewithout
deformingit.Alsotesttthecenteringringinthebodytubeandsandifnecessary.
Spread some epoxy on the outside of one end of the motor tube and slide the tail cone
inplacesothemotortubeisushwiththeaftendofthetailcone.Makesureyouclean
the motor tube of any epoxy so
asnottointerferewiththen
tangs later.
After the tail cone is dry, make a
mark 3/8” 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. 3/8” Exposed
Forward Ring Notch
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.
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.
Spread some more epoxy on the inside edge of the body tube before sliding the tail cone
into the body tube. Continue sliding the assembly inside the body tube until the tail cone

MIM-23B Hawk Assembly ©2007 MadCow Rocketry™ 3
Ensure tailcone & ring
isclearofthenslots
Step 4 – Fin Assembly
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.
Afterthentipshavecurred,sand
the spruce to the same thickness
oftheplywoodn.Alsobevelthe
leading edge of the spruce to match
thesweepofthenleadingedge.
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.Carefullyalignthelongforwardsection
ofthenwithyournalignmentmarks.Securetheforwardsectionofthenwith
maskingtapeagainstthebodytube.Cleananyexcessepoxyfromaroundthenjoint.
Continuerecheckingthenalignmentuntilyouaresuretheepoxyhasset.Repeatfor
theremainingns.Note:Whenassemblinga4nrocket,sometimesitiseasierto
assemblethe2opposingnsatthesametime.Makesurebothnsformastraightline
when viewed from the rear of the rocket. A straight edge held on the aft end of the rocket
can help with this alignment.
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.
Cutalengthofthe1/8”squaresprucejustalittlelongerthanthelengthofthentip.
Epoxythesprucesquaretothetipofthensothatitisushwithbothsidesofthen.
Thiswillacttoreinforcethenbecauseofthehingecutout.Repeatthisstepforallns.
1/8” Square Spruce
isseatedinto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.
Using the same method, pencil a line that
extendsfromeachofthenslotstothe
forward end of the body tube. This will
helpyoualignthelongforwardsectionofthens.

Step 6 – 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.
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.
Step7–FlyingYourModel
Attachtheendoftheshockcordandtheparachuteto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.
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.
24338 El Toro Rd #E-134
Laguna Woods, CA 92637
949.547.8847
www.madcowrocketry.com
©2006 MadCow Rocketry™
®