From: buzz@rsd.dl.nec.com (Buzz McDermott)
Subject: Frequently Asked Questions - Part 2 of 5
Keywords: FAQ
Organization: NEC America, Radio Software Dept
Date: Sat, 21 Nov 1992 17:20:57 GMT
Expires: Sat, 19 Dec 1992 15:00:00 GMT

Rec.Models.Rockets FAQ (Frequently Asked Questions): Part 2 of 5

Last Modified: 20 Nov 1992

*** PART 2: MODEL ROCKETRY

Section 3.1: Model Rocketry Questions

3.1.1 Is the proper term rocket 'engine' or rocket 'motor'?

    Yes.  While some would argue that, technically, it is a rocket 'motor',
    the term 'engine' is used just as much (if not more frequently).
    In this document, the terms are meant to be interchangable and are
    used as such.

3.1.2 Are there any local or national organizations to which I could/should
      belong?

    There are two major national organizations serving the needs of non-
    professional rocketry.  The NAR is the largest and oldest, having been
    formed over 30 years ago.  The Tripoli Rocketry Association was formed in 
    1985 specifically to serve the needs of the high power rocketry community. 
    See the section 'On to High Power' for details on Tripoli.  The addresses
    for both are in the section 'Some Commonly Sought Addresses'.

      National Association of Rocketry
        -sanctions contests
        -insurance for rocket flying activities
        -American Spacemodeling magazine
        -high power certification
        -motor certification
        -NARTREK skills advancement program
        -dues: $25/year (senior)

      Canadian Association of Rocketry

3.1.3 What do the letters and numbers on a model rocket motor mean?

    The NAR has developed a motors classification scheme which has been 
    mandated by NFPA 1122 and most state regulations.  This system
    specifies the motors total impulse class, average thrust, and ejection
    charge delay.  This is printed on any motors certified by the NAR.
    the pieces are as follows, given the example:

        E15-10W

    The 'E' stands for the total impulse class of the motor.  This does not
    mean that the motor has that much power.  Motor classes indicate that a 
    a motor's total impulse falls within a given range.  All motors with total
    impulse anywhere in that range will be in the same motor class.

    The first number after the letter (15) is the AVERAGE thrust of the 
    motor, in Newtons (where 4.45n = 1 pound (lb).  The second number (after 
    the dash, '10') specifies the time delay before the ejection charge fires, 
    in seconds.  The delay time begins AFTER the motor has expended its fuel, 
    not when the motor ignites. 

    Any letter after the delay is manufacturer dependent.  It typically 
    indicates a fuel formulation.

        Letter    Range (NtSec)       Comments
        1/4A        0.00 -     0.62   Model rocket motors
        1/2A        0.63 -     1.25     "      "     "
          A         1.26 -     2.50     "      "     "
          B         2.51 -     5.00     "      "     "
          C         5.01 -    10.00     "      "     "
          D        10.01 -    20.00     "      "     "
          E        20.01 -    40.00     "      "     "
          F        40.01 -    80.00     "      "     "
          G        80.01 -   160.00     "      "     "
          H       160.01 -   320.00   High power rocket motors
          I       320.01 -   640.00     "    "     "      "
          J       640.01 -  1280.00     "    "     "      "
          K      1280.01 -  2560.00     "    "     "      "
          L      2560.01 -  5120.00     "    "     "      "
          M      5120.01 - 10240.00     "    "     "      "
          N     10240.01 - 20480.00     "    "     "      "
          O     20480.00 - 40960.00     "    "     "      "

    Engines of type 'G' or less, and having less than 62.5 grams (2.2 ounces)
    of propellant are classified as DOT Class C Toy Propellant Devices and are
    'model rocket' motors.  Anything larger is a Class B, 'high power' motor
    and their use falls under much stricter regulation.  'G' motors are
    currently a special case.  The has been a conflict between the CPSC, NFPA,
    and DOT definitions of a "model rocket motor" that may be freely purchased
    by individuals.  The CPSC ruled 'G' motors as 'Banned Hazerdous
    Substances' unavailable for general purchase.  A stay of enforcement has
    been granted to at least one manufacturer of 'G' motors, and the issue
    is under review.  For now, 'G' motors may be treated as any other model
    rocket motor.

3.1.4 Can I legally fly model rockets in my state?  What are the restrictions?

    Several states still require some type of permit to fly model rockets.
    The requirements vary greatly between the states.  Also, local 
    municipalities are free to impose additional restrictions beyond those 
    defined in NFPA 1122 and any state laws.  Check with your local fire 
    marshal for restrictions in your area.  For example, the states
    of Massachusetts, Rhode Island, and California all have stricter
    regulations than NFPA 1122.

3.1.5 I have a son/daughter that is (6 - 9) years old.  Is this too young for
        model rocketry?  If not, are there any tips for helping to keep their
        interest in the hobby?

    Model rocket manufacturers all recommend adult supervision for young
    children (usually, those under 12).  Many parents have had great success
    introducing these children to model rocketry.  Here are a few of the tips
    and suggestions posted to r.m.r:

    From cdt@rocket.sw.stratus.com (C. D. Tavares):
      Children under 10 or 11 do best in the hobby when a parent participates
      actively with them.  Introduce them to simple, skill-level-1 kits with
      plastic fin units.  Build yourself a rocket at the same time, then go
      out and fly them together.

    From jack@rml.com (Jack Hagerty):
      My own experience with my son (now 5 1/2, we've been flying since he 
      turned 4) is not to expect too much sustained interest at a time. Even 
      though my son has a longer-than-normal attention span for his age 
      (he'll watch a whole two hour movie!) and loves the whole idea of 
      building and flying rockets, after 4 or 5 flights (approx 1/2 hour) 
      he'd rather go play on the monkey bars at the adjacent school.
      This is magnified if there are any kids his own age around (such as his
      cousins that sometimes come with us).

    From dwade@jarthur.Claremont.EDU:
      Watching they should enjoy.  Pressing the button they should enjoy.
      Prepping with serious supervision.  Building simple kits with some 
      supervision and a pre-launch check.  There's a huge difference in 
      responsibility between kids.  One thing to stress is that a lot of very 
      careful kids will get bored or get pressured by bored friends to do 
      stupid things when you're not around.  I might not let kids have any 
      access to motors when unsupervised -- and there's no real reason why 
      that should cause them any trouble.  It is possible to make safety fun, 
      you know.  I think that's something that a lot of people miss -- if you
      present things that way, it seems to work out.  I don't have kids, but 
      I've got rocket launching friends who do.

    From J.COOK@ens.prime.com (Jim Cook):
      I've successfully built an Athena and an America with a 7 year old.  
      The body tube is pre-painted, the decals are self-adhesive, and they 
      like the gold or silver chrome nose cone.  You can build it in an hour 
      or two - just let them run around and call them over to help periodic-
      ally - "glue here", "cut here", "hold this".  They feel it's still 
      their rocket and that they helped.  Estes new E2X series may also be 
      similarly suitable, but I haven't tried, yet [ed. note:  the E2X 
      series go together with plastic model cement, such as Testors, not 
      white glue].

      Estes' new E2X series is similar in construction to the Athena and 
      America - they can be built in an hour or two with kids.

      Demo a range of motors.  Go from 1/2A to A to B with a model to 
      show kids the difference.

      Kids will invariably talk about launching them out of site or
      sticking a firework in them.  Answer with, "yeah, but I wouldn't
      want to wreck my model that I spent so much time building."  Making
      the kid answer forces him [or her] to think and teaches him [her]
      to value his [her] possessions.

    From buzz@rsd.dl.nec.com (Buzz McDermott):
      I've been building model rockets with my 9 year old son for the past 18
      months.  He builds plastic model planes and cars so the E2X kits from
      Estes work great for him.  We started with the Alpha III.  Now he 
      won't build Level I kits with single piece fin units.  They're 'too
      easy'.  He now preps and launches his own rockets.

      My six year old daughter and I just built our first rocket together.
      It was an Estes 'America'.  She was able to do most all of the work,
      with close supervision.  She especially liked helping to put the 
      plastic chute together.  It took about 1 hour, total, for us to put
      it together.  This included plenty of time for me to explain what 
      each piece was for.  When we flew it at the next local club launch
      I prepped the rocket (she 'helped' by putting in the engine and putting
      on the nose cone); she insisted on recovering it herself and loved it.
      I used B motors to keep it from drifting too far.  I recommend any of
      the Alpha III, Athena, or America as first kits for younger children.
      The Quest Falcon is also a good choice.

    From jstewart@software.mitel.com (John Stewart):
      My daughter loves rocketry. She started when she was 3. Get colorful
      rockets, build them yourself (e.g. the plastic Alpha II(?)), and don't
      fly them too high. (50-100' is more than fine) Let the child count to 5 
      (or try to!!) and push the button. Let them recover the rockets.  Have
      say, 5 to 10 rockets loaded, ready to go when heading out. Launch them,
      and untangle/fix them either at the field, or at home later, depending
      on the child's mood.  My 4-3/4 year old daughter is looking forward to 
      launching, possibly this weekend. We spent a year in New Zealand, but 
      she still knew all about the rockets, the parachutes, the streamers...

    From rbs@cyclops.micr.Virginia.EDU (Robert Sisk):
      People interested in easy to build model rocket kits for the younger
      crowd should check out QUEST models.  Some of the parts are color
      coded (centering rings, engine blocks, engine mount tube) and the fins
      of some models are plastic.  Some of the fins are supplied as a single
      unit that you glue into place.  Fast, easy, and with little or no 
      sanding!

3.1.6 Is there any way I can buy model rocket kits, parts and engines at less
      than full retail?  How about mail order?  Note:  for additional
      addresses, refer to the list of suppliers maintained by R.M. Jungclas 
      (see Section
      1.3.3).

    One mail order house has been recommended several times by posters to 
    r.m.r.  It is Bellville Wholesale Hobby.  It sells MRC at 40% off list, 
    Custom Rockets at 35% of list and Estes at 30% off list.  There is a 
    minimum order requirement.  For information and a catalog:

        Belleville Wholesale Hobby
        1827 North Charles Street
        Bellville, IL 62221-4025
        Phone: (618) 234-5989
        Fax:   (618) 234-9202
        Catalog: $2.00

    The following individual has been mentioned as a source for cheap 18, 24,
    and 33mm Estes-style body tubes (BT-20, -50, and -55, respectively), if 
    you are will to buy by the dozen (or more):
 
        Lou Scavone
        41312 Memphis Drive
        Sterling Heights, Michigan
        (313)739-3058

    Another potential source of 'inexpensive' body tubes is:

        Fred Shecter
        20505 E. Clear Spring Court
        Walnut CA 91789

    Fred is with the LA Rocket Society.  He is purported to have craft paper 
    tubes in lengths up to 34-36 inches.
     
    In Canada:

        OAS (Orleans Automation Systems) Rocketry Division
        Suite 606, 116 Albert St.
        Ottawa, Ont.
        K1P 5G3
        (613) 233-1159
        (613) 830-5811 (fax)

    If you do a fair amount of flying, Estes sells a 24-pack of engines called
    the Flight Pack.  It comes with 6 A8-3, 6 B6-4, 6 C6-5, 6 C6-7, recovery
    wadding and igniters.  It generally retails between $25-28, which is less
    than the list price of the materials included.

    Quest motors have been recommended by several r.m.r posters.  At the 
    present time, they retail at less than the Estes equivalents.

    You might also investigate your local NAR section, if one is located 
    convenient to you.  Clubs such as NAR sections often arrange discounts
    with local hobby merchants.  Several of the clubs also have at least
    one member selling parts and supplies at discount, mostly to the 
    club members.

    If you are looking for composite model rocket motors (i.e., Aerotech
    D & E motors) your best bet for discount prices would be some of the 
    high power mail order addresses listed in Section 8.12.

3.1.7 I've had a large number of motors CATO recently.  The engines are only
      about 2 years old.  I've had them stored in my (attic/garage/basement).

    From J.COOK@ens.prime.com (Jim Cook):
      Black powder motors tend to suffer catos when they are temperature
      cycled.  If you expose them to heat, be it storing them in the attic,
      on your car's dashboard, or in your metal range box in the hot sun on
      the launch field, you may have problems.  The engine expands with the
      heat, but when it cools, the propellant separates from the casing 
      inside This causes the propellant to burn faster due to burning on the
      side generating more pressure than was designed for, and ...boom...

      Storing black powder motors in a damp basement can cause the compressed
      clay nozzles to soften and also blow out.  If you must store your motors
      in a damp/humid area, put them in a zip lock plastic bag.

		[Note: There is an excellent article by Mat Steele in the May/June 1992 
             issue of American Spacemodeling.  This article goes into the 
             theoretical reasons why black powder model rocket motors fail]

3.1.8 Is it safe to use my old rocket engines from <nn> years ago?

    From J.COOK@ens.prime.com (Jim Cook):
      I've had properly stored engines from 1972 and 1975 work just fine.
      If you suspect a motor, fire it by burying it in the ground with just
      the nozzle showing, pointing up and use your launch system to ignite it
      as usual. [Note: be sure and stand at least 15-20 feet away from the
      motor when you fire it: Buzz]

3.1.9 What's a good way to find other rocket enthusiasts in my area?  How
      can I found out about local rocket clubs?

    The NAR sends a complete list of its local sections (NAR sanctioned 
    clubs) with each new member's information packet.  If there isn't
    a sanction near you they have a service to send you a list of
    other NAR members in your area, so that you can form your own
    section.

3.1.10 NFPA, FAA, DOT, ...  Who are all these organizations and how do they
       affect the rocketry hobby?

    DOT:  (Dept. of Transportation) regulates shipping of rocket motors and 
          reloads.
    CPSC: (Consumer Protection Safety Council) regulates what may and not
          be sold as a 'consumer' item
    FAA:  (Federal Aviation Administration) is responsible for airspace 
          control and regulates flights rockets that exceed 1 pound and
          enter FAA regulated airspace.
    NFPA: (National Fire Protection Association) regulates the use of non-
          professional rocket motors.  Most state and local laws concerning 
          the use of model rockets are based, in part, on NFPA rulings and
          regulations; especially NFPA 1122.

----------------------------------------

Section 3.2: Born-again Rocketeers

3.2.1 I have been out of model rockets for many (i.e. <nn>+) years now.
      All I ever used were Estes/Centuri/FSI kits. I never knew of anything
      else. I would appreciate it if someone could tell me more about
      what is going on in the sport/hobby currently.

3.2.2 Who's Left, Who's Not & Who's New

    Basically, it's all pretty much the same, or totally different,
    depending on your interests.  Estes is still Estes.  Most of their kits 
    are still the same materials, etc.  The trend for the last 10 years has 
    been for Estes to sell simpler and simpler kits.  There are lots of 
    plastic nose cones and fin units (already around when you were active 
    before).  There are now kits with pre-slotted body tubes and plastic 
    fins (as in the Estes E2X series).  Lot's of good stuff for beginners 
    and kids.  Estes still makes engines in the 1/2A - D range, all black 
    powder.

    Flight Systems is still here, selling kits and black powder engines in the 
    A-G range.

    Centuri, sadly, 'went away' in 1980.  Daemon Industries bought both Estes
    and Centuri in the 1970's.  They operated both companies as independent 
    units for several years.  Finally, Centuri was dissolved and its products
    absorbed into Estes.  Every now and then an old Centuri kit surfaces
    under the Estes banner.

    Now for 'who is new'.  First, in model rocketry there is a new kid
    on the block: Quest.  This is Bill Stine, some ex-Centuri people
    and others.  They are a direct competitor to Estes.  They have a line 
    of kits and engines (A-C).  Good quality.  Cheaper than Estes.

    If you were into competing you might have been familiar with Competition
    Model Rockets (CMR).  They are now defunct but there are constant rumors
    of a rebirth sometime in 1992.  Other companies have stepped in to fill 
    the space left by the exit of CMR.  See the section 'Competition' for some
    names and addresses.

    A lot of the 'neat' Estes kits of the 60's and 70's are no longer 
    available.  However, Estes is bringing them back (one by one) in so-
    called, 'limited run collector series'.  The first one of these is the 
    'Mars Snooper' kit from the 60's.  The Orbital Transport and other kits 
    are supposed to be forth- coming.  WARNING: expect to pay up to EIGHT 
    TIMES the original list price for these re-vamped kits.

3.2.3 Changes in Motor Technology

    The big changes have come in motors.  Expendable composite fuel motors
    are now available in D-G range for model rockets (G motors are 
    currently listed as banned devices by the CPSC and NFPA). These motors
    use ammonium perchlorate for fuel, similar to the rocket boosters on
    the space shuttle, allowing them to pack two to three times the power
    in the same space as a black powder motor. The D motors are the
    same size as Estes A-C motors (18x70mm).  This D is also a full 
    D power rating of 20 Newton-seconds, versus the Estes 24x70mm D of about
    17 Newton-seconds.  There are a couple of E motors the same size as 
    Estes D motors.  All of the motors give Estes kits an incredible ride, 
    if the models hold together.  The E-G power ranges are now sometimes 
    referred to as 'medium power'.  These are usually still model rockets
    (i.e., under 1500 gram launch weight).  These kits require stronger 
    construction methods and materials than typical model rockets.  Put an 
    Aerotech D21 or E25 in your old Big Bertha at your own risk!! You're 
    likely to end up with a model with no fins (i.e., a complete 'shred').

    Aerotech is the current leader in model rocket composite motors.  They 
    have D through G  expendable motors.  Vulcan Industries has announced 
    that they will be supplying Estes with Class C composite motors for a
    new line of rockets Estes will be coming out with in late summer/fall 
    of '92.

    Another new trend is 'reloadable' motor technology.  With reloadables
    you have a metal motor casing that you manually reload with solid fuel 
    pellets, delay and ejection charge for each flight.  The casing is 
    reusable.  Reloadable motors are available in everything from 18x70 mm 
    (with B - E power), 24mm, (with D - F power), 29mm, 38mm, and much 
    larger.  Again, you can get all the way up to 40,000+ Newton-seconds of 
    total impulse.  NOTE: NO RELOADABLE ENGINE IS A MODEL ROCKET ENGINE, NOT 
    EVEN THE SMALL ONES!! The NFPA (National Fire Protection Association) 
    has banned general use of the motors.  Only certified organizations, and 
    their members, can legally use them.  NAR and Tripoli members are 
    currently, temporarily, certified to use reloadable motors.  All of this 
    is in a state of flux and is currently on the agendas of the NFPA, CPSC,
    and DOT.  See section 8.5 for additional information.

3.2.4 High Power Rocketry

    Now there is also HIGH power rocketry (HPR).  These are rockets with 
    motors up to type O (with greater than 40,000 Newton seconds of impulse).
    There has been a lot of discussion about high power recently.  You have to
    be a member of either the NAR or Tripoli to fly rockets with H motors or 
    above.  To fly with H or above both organizations require that you be 
    'certified' by safely demonstrating a successful flight with a high power
    model in the presence of one or more 'qualified' members of the 
    organization.  There is now a HPR safety code as well as the original 
    model rocketry safety code.  There are expendable and reloadable 
    (discussed below) HPR motors available.  They are increasingly 
    expensive as the power goes up ( $10 for a G up to hundreds of dollars 
    for a really big (O) motor).  High power rockets start where model 
    rockets leave off (i.e., > 1500 grams).  High power models weighing
    more than 50 pounds are not uncommon.

    There are several manufacturers of high power kits and motors.  See the
    sections 8.3 and 8.12 for high power addresses.

    Oh, yes, HPR requires a duly authorized, signed-in-blood (in triplicate, 
    etc. :-) FAA waiver for each day you wish to fly.  It is ILLEGAL to fly
    high power rockets without a proper waiver. See section 8.7 for more
    information on FAA waivers.

----------------------------------------

Section 3.3: Scale Modeling

3.3.1 I would like to make a scale model of the <??> rocket.  Where do I start
      looking for technical data, dimensions, flight substantiation data, 
      etc.?

    Two places to start looking would be Peter Alway's book of scale data.
    Another source is the list of scale data sources maintained by Kevin 
    McKiou and posted periodically to this newsgroup.  Refer to the section 
    'Other Sources of Information' in this FAQ for more details on these.
    Back issues of _American Spacemodeling_ are another excellent source
    of scale information and data.
    
3.3.2 I've never built any scale models.  Are there any recommended kits for 
      first timers?

    The following recommendations have been made by posters to r.m.r:

    For A-D powered rockets:
      Estes IRIS (A-C power, sport/semi scale)
      Estes Black Brandt II (D power, sport/semi scale)

    Larger models:
      North Coast Rocketry Patriot (E/F/G power, sport scale)
      Aerotech ISQY Tomahawk (E-G power, scale)

----------------------------------------

Section 3.4: Model Rocket Construction and Finishing Tips

    This section includes tips and suggestions on various topics having to do
    with construction and finishing techniques.  These have been posted to 
    r.m.r or mailed to the moderator by way of r.m.r request.  Refer to this 
    same section in Part 3 of the FAQ (High PoweR) for additional tips,
    oriented towards high power and advanced rocketry requirements.

    Cutting, Sealing, Attaching Fins
    --------------------------------

    From J.Cook@ENS.Prime.COM (Jim Cook):
      Skip using glue W/ balsa dust, dope, or any other junk for filling the 
      grain in balsa fins or nose cones.  Use Elmer's "Fill 'n Finish" diluted
      with water to a thick paint (like white glue is) and paint it on.  
      Non-toxic and a coat or two will do.  Use Elmer's "Carpenter's Wood 
      Filler" thinned similarly to fill the spiral in body tube.  Both come 
      in a white plastic tub with an orange lid.  Note - the latter is 
      harder to sand, so don't make the mistake of using it on balsa as it 
      will require a lot of sanding.

    From cdt@pdp.sw.stratus.com (C. D. Tavares):
      Fill your fins BEFORE attaching them.  (Don't fill the root edge).

    From: utidjian@remarque.berkeley.edu (David M.V. Utidjian):
      [To hold fins in place and aligned while drying I bought an Estes
      fin alignment kit].  At 15-16 bucks it seems a bit
      expensive but is well worth the aggravation and time it saves.  You
      can even make your own if you are handy.  I just set up my body tube
      in the jig and then check the alignment of all of the fins to the body
      tube. Then I use a thin bead of 5-min. epoxy. and in ten minutes I am
      done.  When I do the fillets I can do them all at once but don't have
      to worry about the softening the glued on fins so they droop.  You
      still have to lay the model on its side though but only for 5 minutes.

    Body Tubes (Cutting, Joining, Filling)
    --------------------------------------

    From cdt@pdp.sw.stratus.com (C. D. Tavares):
      [On cutting Estes-style body tubes]
      The simplest and best I ever used was Howard Kuhn's jig from the old CMR.
      It's a simple piece of wood L-angle moulding, with a notch for a razor
      blade cut into one side (from the wing toward the elbow) at one end.
      The only other parts are a wood block and a large black spring clip (the
      kind you hold really thick reports together with).  If you want, say, a
      6" piece of tubing, you set the block 6" away from the razor notch and
      clamp it there with the spring clip.  Now lay the tube down the L-angle,
      butting it up against the wood block.  Insert the razor blade, press
      lightly, and turn the tube.  (Put a dead engine into it if the tube is
      the right size to fit one.)  Three to six turns, and you have an edge
      that looks factory-cut.

                       ----
                      (    )  <- spring clip            | <- razor (edge on,
                       /  \                             |    sharp edge down)
        ____________---------___________________________|_______
       |          /_|       |__/|                       |       |
       |          | |_______|  ||  angle moulding       |       |
       |          | wood block ||                               |
       |----------|____________|/-------------------------------j
      /                           lay tube here and spin it    /
     /________________________________________________________/

    From: umn.edu!ux.acs.umn.edu!vx.acs.umn.edu!soc1070 (Tim Harincar)
      When I cut tubes, I always wrap the tube with about two
      layers of drafting tape with the edge of the tape along
      the cut line. This accomplishes two things: First the
      thick tape edge providing a excellent knife guide. Second,
      you can assure a straight cut. If the tape wrinkles when
      you wrap the tube, you know it is not on straight; simply
      remove the tape and try again until you know its down flat.

      Drafting tape is better than regular masking tape because it
      has almost the same thickness but is made to be removed.

      This method is in addition to reinforcing the inside with
      a stage coupler or spent motor. Also, always use a new
      x-acto blade for the best cut.

    From Jim Bandy (NAR member not on net):
      Use a piece of aluminum 'angle iron' for joining body tubes.  Place one
      tube in the angle, insert and glue the joiner, then insert and glue the
      other tube.  It give very straight joins.  The angle can also be used
      for marking fin lines on body tubes, etc.

    Parachutes
    ----------

    From: soc1070@vx.acs.umn.edu (Tim Harincar)
      Making your oun parachutes is pretty easy. Start with the desired 
      material (usually mylar or a light plastic). Make a cutting pattern out 
      of cardboard by first drawing a circle that will be the maximum size 
      of the chute (i.e. 16"). Take a compass [or] something that will give 
      you an accurate radius of the circle. Pick a point anywhere on the 
      circle and using the radius as a length draw an arc that crosses the 
      circle. At the point where the arc crosses, reposition the compass on 
      that point and draw another arc.  Keep doing that all the way around 
      the circle - you will end up with six points including the starting 
      point on the circle. Connect these points with a straight edge and 
      Presto! a hexigon. Cut out the hex from the cardboard (I use artists 
      matboard...) and this is your cutting template. Lay the template on 
      the material and using an EXTREAMLY SHARP XACTO KNIFE cut along the 
      outside of the template.  Make shrouds from a heavy guage thread - 
      cut three equal lengths twice as long as the diameter of the chute and 
      connect the ends to corner points adjacent to each other.
 
    From: Roger.Wilfong@umich.edu
      I usually build 12-24 line round chutes out of Estes material (just cut 
      around the outside of the red and white circle and attach at the red
      /white boundaries) because they look more like real parachutes.  I use 
      embroidery floss for shroud lines and separate the 6 strands (for 12 
      lines - use two lengths for a 24 line).  This makes a strong chute.  
      With out crossing the lines over the top of the canopy, I've only had 
      one failure of a 12 line chute (an EL that tipped off dramatically - 
      i.e. cruise missle) and never had a 24 line fail.  In the 10 years 
      I've been back in the hobby and using this technique, my shroud lines 
      have always come out the same length (within a couple of percent 
      tollerance).

    From: hal@HQ.Ileaf.COM (Hal Wadleigh)
      1. Use fisherman's snap swivels for your attachments.  It lets you 
         store 'chutes separate from rockets and helps prevent fouling due 
         to spin at deployment.[Note...modelers have always reported mixed
         results with snap swivels; they have been known to fail...Buzz]
      2. Use nylon coat thread for shroud lines on homemade 'chutes (and 
         plastic bread wrappers are the best cheap 'chute material).
      3. Pay special attention to the security of the attachment points.  
         Those standard stickers often look secure, but are actually not 
         attached.  A small knot in the part of the shroud line under the 
         sticker serves as a good anchor point (with the rest of that part 
         looped around the knot, as per standard practice).
      4. Very small 'chutes should be crossform type.  Cut about a 5" square,
         then take out about 1.25" squares from each corner.  Attach 4 lobes 
         of shroud across the flat ends and secure as above.  Be careful to 
         use small stickers for the corner attachments.  These make good 
         substitutes for streamers in .5" body tubes and can also be used as 
         drogues to help in the deployment of large 'chutes [A note from
         cdt@sw.stratus.com (C. D. Tavares): Either round off the inside 
         corner of that 1.25" square or reinforce the angle with something.  
         Otherwise, it's a really handy place for the parachute to rip  
         during a fast deployment.]

    From: smith@mrcnext.cso.uiuc.edu (Greg Smith)
      Nylon coat thread is very good for small, lightweight competition 
      parachutes, but it's not real strong and does have a tendency to melt if
      it encounters a bit too much ejection charge heat.  For sport and 
      payload models with 12" - 24" plastic 'chutes, I use 15 lb. *braided* 
      nylon fishing line.  It's thicker than the coat thread, similar in 
      diameter to the Estes cotton stuff, but tremendously stronger.  In the 
      last fifteen years, of the plastic parachutes I have built using this 
      line (and always crossed over the top of the 'chute for reinforcement), 
      I have had *zero* shroud line or attachment failures.  The braided line 
      has a hard, smooth surface that doesn't encourage tangling, and it 
      doesn't unravel where cut.

    From: whitman@nssdca.gsfc.nasa.gov (Rusty Whitman)
      I've tried about everything to keep shroud lines from pulling off of
      plastic or mylar parachutes.  Those little tape disks are just about
      worthless.  Tying knots and cyano'ing the ends helps but you still
      have problems.  I don't know why I never thought of this before but I
      ran across a roll of duct tape in my closet and knew immediately that
      that was the answer.  I cut out some little squares of duct tape and
      attached some lines to a parachute and they won't pull free without
      ripping the plastic.  I don't know who invented duct tape but they
      deserve some kind of statue, its got more uses than a paper clip.


    Miscellaneous
    -------------

    Source unknown [but sounds like good advice to me...Buzz]:
      Make a jig for anything you do more than once (align fins, 
      join body tubes, etc.).

Newsgroups: rec.models.rockets