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  1. #1
    Join Date
    23rd December 2016
    Location
    Georgia, USA
    Posts
    15

    Just a few questions about building from scratch

    Alright so I'm new to The Rocketry Forum and I apologize if this isn't the correct place to post this thread. I'm kind of a newbie to scratch rocketry so I just had a few questions for some of the more experienced users.

    How do you determine the ideal rocket length?
    What are some good/cheap materials for each part of a rocket? Also good places to look for supplies?
    How do you decide what to build a rocket for? (For launching an egg safely, GoPro, etc. or just building a rocket for no specific reason? Do you design each rocket specifically for an intended purpose from the ground up?)

    Any other suggestions or links or reading materials would be greatly appreciated so I can further my interest in rocketry. Thanks in advance!

    EDIT: Just realized there was a scratch rocketry forum. Sorry for posting here.

    Last edited by AidanDelli; 29th December 2016 at 10:47 PM.

  2. #2
    Join Date
    21st April 2010
    Location
    So central WI, USA
    Posts
    5,155
    not a problem, there is more traffic here and these are 'beginers' type questions... think most of us these days use design software (openrocket is free) to assist the process (and figure out which motors to use).
    normal size rockets range in size(length) from 8x to 15x the body tube diameter. I generally just build for the fun of it with no particular reason in mind other than perhaps to try out some different ways of doing things (fin shapes or whatnot) one can generally find balsa at the local hobby shop.
    Rex

    L2-competitor 3, AT J350W, 8/27/2016, Bong, 2557'
    my youtube channel http://www.youtube.com/channel/UC0gB...?feature=watch

  3. #3
    Join Date
    27th March 2013
    Location
    Has Changed
    Posts
    8,866
    Welcome! No need to apologize.

    As to materials, it depends on what diameter you're looking for. There are a lot of options for body tubes available from manufacturers, specifically for rockets. Other sources include such things as fluorescent Tube Protectors, Crayon banks, mailing tubes, PVC pipe (which is frowned upon by lots of people, yet apparently can be made to work (I've got a couple of designs that I'd like to build that way)), concrete forms. I wouldn't be surprised if someone made a rocket out of a Christmas wrapping paper tube. Some people actually go so far as to make their own mandrels and tubes.

    Basically, if it's a tube, and it's not made of glass (barring fiberglass), or metal (outside of HPR stuff), it's built into rockets, or will be built into a rocket someday.

    Why do we build what we build? I think it's fair to say we love the hobby, and the thrill of seeing something we built launch on a column of smoke and flame. It doesn't matter if it can launch a payload (egg, insect, diet coke (guilty), bowling ball, or a keg of beer), if it flies, and looks good to us, we build.

    Reading?
    Handbook of Model Rocketry by G. Harry Stine.
    Model Rocketry Hobby of Tomorrow by Peter Lowry & Field Griffith (it's old, but fun)
    Modern High-Power Rocketry 2 (and presumably its predecessor) Mark Canepa
    Sport Rocketry Magazine published by the National Association of Rocketry

    +1 on OpenRocket. For fun, you can check out my files thread.
    Last edited by K'Tesh; 30th December 2016 at 02:22 AM.
    Dreaming of making the rockets I dreamed of as a kid (and then some).


    NAR L1 Cert flight: Sheridan, Oregon, USA. Sept. 19, 2015. Flew Deep Space OFFl on an I357T-14A Blue Thunder

  4. #4
    Join Date
    31st January 2013
    Location
    Atlanta, Ga
    Posts
    840
    Quote Originally Posted by AidanDelli View Post
    Alright so I'm new to The Rocketry Forum and I apologize if this isn't the correct place to post this thread. I'm kind of a newbie to scratch rocketry so I just had a few questions for some of the more experienced users.
    I'm with Rex here, this is a good place for these questions. They will get more traffic and possibly steer some new folks toward investigating scratchbuilding.

    Quote Originally Posted by AidanDelli View Post
    How do you determine the ideal rocket length?
    +1 for Openrocket. It is a quick and easy way to explore the various design elements of a rocket and their effect on performance. After you design, build and fly a few rockets, mindsim will become much more accurate and OR will be more of a design tool and confirmation of your gut feeling. Keep in mind that Openrocket is an open source, free program. It does not have some of the capabilities of Rocksim but it gets the job done quite well and you can't beat the price.

    Quote Originally Posted by AidanDelli View Post
    What are some good/cheap materials for each part of a rocket? Also good places to look for supplies?
    CheckBalsa Machining Service or eRockets. Both are good sources of building supplies but are, by no means, the only ones out there. (BMS website is currently down for maintenance)

    Quote Originally Posted by AidanDelli View Post
    How do you decide what to build a rocket for? (For launching an egg safely, GoPro, etc. or just building a rocket for no specific reason? Do you design each rocket specifically for an intended purpose from the ground up?)
    I build scratch rockets that seem fun at the time. Inspiration may be from a favorite kit that you want to up scale (or down scale). Maybe you get an idea for a design element that you haven't seen in a kit. My current fascination is for rockets that fly on Estes F15 motors. I just play with OR sometimes and I have a boat load of designs that I may build one day.

    Quote Originally Posted by AidanDelli View Post
    Any other suggestions or links or reading materials would be greatly appreciated so I can further my interest in rocketry. Thanks in advance!
    Apogee Components is a great source of information as well as being an A to Z source for anything that you need for rocketry. I especially enjoy the newsletter and some of their construction videos. I have done two scratchbuilds inspired by one of the newsletters.

    I will add one to the reading list, Make: Rockets. It does cover the same information as The Handbook but it takes a much deeper dive into the science behind the techniques and presents a build project to explore each concept.

    Quote Originally Posted by AidanDelli View Post
    EDIT: Just realized there was a scratch rocketry forum. Sorry for posting here.
    Careful here, DaddyisaBAR hangs out here on occasion and he may lure you down into the Oddroc forum where the dark arts of model rocketry are celebrated. Trust me, once you venture here, resistance is futile. I have had to resort to ideas that are beyond my current capability in order to keep from building things with canted motors and performance robbing nose weight, but the end result is inevitable.
    Bill

    I won't be wronged, I won't be insulted, and I won't be laid a hand on. I don't do these things to other people and I expect the same from them.
    John Wayne, The Shootist

    In the Hangar:
    A pile 'O' Fun

    On The Bench:
    Pieces 'O' Fun

  5. #5
    Join Date
    23rd December 2016
    Location
    Georgia, USA
    Posts
    15
    Thanks for all the info guys! I will definitely use the suggestions that you guys offered.

  6. #6
    Join Date
    17th December 2013
    Location
    Slagle, La
    Posts
    837
    Check out this thread for a list of suppliers/sites:
    http://www.rocketryforum.com/showthr...etry-Resources
    Exactly what resources you want or need depends on how big, hard, fast, or high you want to go.

    For the lighter stuff and BT sizes, Balsa Machining Services was mentioned already, and I'll add Uncle Mikes Rocket Shack and Sirius Rocketry.

    For some heavier, bigger stuff check out Loc Precision, Madcow, Binder Design, and Wildman. Just go to their Components section. Mac Performance also has components for upper class birds.

    For good inexpensive custom chutes see Top Flight and DinoChutes. Both do custom work and easy to work with.

    There are many more, but just those few websites will keep you busy and considering a second job and/or mortgage. Most sell more then just components and offer a plethora of kits you can look at and get ideas.

    When you get into reloads, vist Chris at https://www.csrocketry.com He is primarily a motor dealer, but also has kits and supplies aimed more toward HPR.

    Mikey D
    Nothing is foolproof to a sufficiently talented fool.
    TRA #16513
    Level 1: Danger Close ---AT H123W to 1240'--- 29 OCT 2016

  7. #7
    Join Date
    25th February 2014
    Posts
    435
    "How do you determine the ideal rocket length? '

    if it can fit in my car, its not too big.

  8. #8
    Join Date
    5th February 2009
    Location
    Montreal, Qweebec
    Posts
    2,797
    Let's look at it a bit differently.

    it can also be [very!] loosely based on a 'kit bash'. Scratch build may also be a way to use up old stock (from various / previous kit bashes). Always save NCs! (Nose Cones)

    Go buy kits on special. You don't have to like them, that's not the point. You're buying for parts. Eventually, you'll need to buy a few CRs (centering rings) or extra lengths of BTs (Body Tubes) to use up acquired stock. But, with a few kits you can interchange the parts to make new rocket designs, modify the stock fins to have an extra step or swoop on them, make more of them, add a transition, etc..

    Some basics:

    rocket length: Typically 10:1 or longer. (10 times the body diameter. A 1.5: dia rocket should be at least 15" long)
    fins: 3 minimum, and the root should be 2x the BT dia, and 1x the BT for height, and 1Bt for the tip. So, the 1.5" dia rocket should have 3 fins of 3" at the root, 1.5" tall, and 1.5" at the tip.. There are compromises you can make.. remember to have the wood grain follow the leading edge of the fin! (Ply , G10, etc.. need not apply!)
    At least one launch lug, 2 are preferred. Always 2 buttons!
    Recovery with a chute or streamer, there are calculators to determine proper chute size based on weight & desired decent rate..
    Shock cord is usually at least 3x the rocket length, I try to go 5x, but within reason! and rated for 150x rocket weight..
    Always sim or swing test your design.

    I do my scratch builds based on "what looks cool!!"
    -paul

    NAR# 101258 - L1
    www.CRMRC.org
    I don't know the same things you don't know..

  9. #9
    Join Date
    27th August 2011
    Location
    West Tennessee
    Posts
    2,524
    All above good.
    Especially recommend
    Handbook of Model Rocketry.
    You don't say much about your experience. In general you will get a pretty good feel just by building a few kits.
    I think it was Carl Sagan who said
    To truly make an apple pie from scratch first you have to create the universe.
    Scratch rocket building can go from kit bashing to rolling your own tubes and making your own nose cones (check out card stock Rocketry )
    Sounds like you want to be creative which is mucho cool. Unless you have a lathe or other special tools, I would recommend you scavenge parts from kits, use premade nose cones and body tubes (uncle mikes rocket shack is my go to for these.) balsa is easy to find from your local hobby lobby is U.S., the 40% off coupon which you can pull up on your smart phone is nice.
    Post pics and the rogues on the forum will probably be able to give you an idea if it will be stable.
    Best of luck

    It is amazing what you can do when you don't have a choice.

    Smart people learn from their mistakes.
    REALLY SMART PEOPLE learn from OTHERS' mistakes.

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