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  1. #1
    Join Date
    21st May 2017
    Posts
    5

    Launch Lugs Alternatives?

    Hey all!

    I am working on a completely homemade rocket, and am wondering if there are any plausible alternatives to launch lugs. I currently use a simple fiberglass rod staked into the ground with a metal duct cover to protect the ground. It works well, but seems as though the system kills the velocity. In OpenRocket, estimates show that using launch lugs decreases my maximum velocity by about 30 m/s which is quite significant.

    Any advice appreciated!


  2. #2
    Join Date
    14th March 2009
    Location
    Ohio
    Posts
    3,113
    For competitions our club uses launch towers. Essentially, the rocket sits in the middle of three rods that keep the rocket pointing up for the first meter of travel. They can be rather expensive as they are designed to be adjustable to handle rockets of many different diameters. If you are only making one for a specific rocket you could just use three or four rigid poles. Make sure you look at designs online and note that they all have something at the top or along the length of the rods to keep them rigid enough to keep the rocket trapped inside. Three rods stuck in the ground will NOT be sufficient.

    I assume you are not in the U.S. as you are using meters. You might want to look for a local club and see if they have a launch tower.

    Are you making your own motors too? That isn't something we talk about in the open forum for a number of reasons.

    Zeus-cat
    NAR# 92125 L1
    Total Impulse for 2017: 1,493.8 N/s Flights: 56
    2017: 1/2A:0, A:6, B:11, C:2, D:12, E:4, F:1, G: I have NEVER launched a G motor, H:1, I:1

  3. #3
    Join Date
    21st May 2017
    Posts
    5
    Quote Originally Posted by Zeus-cat View Post
    For competitions our club uses launch towers. Essentially, the rocket sits in the middle of three rods that keep the rocket pointing up for the first meter of travel. They can be rather expensive as they are designed to be adjustable to handle rockets of many different diameters. If you are only making one for a specific rocket you could just use three or four rigid poles. Make sure you look at designs online and note that they all have something at the top or along the length of the rods to keep them rigid enough to keep the rocket trapped inside. Three rods stuck in the ground will NOT be sufficient.
    Do you have a picture of what it should look like?

  4. #4
    Join Date
    1st September 2010
    Location
    Tucson, AZ
    Posts
    1,037
    A piston launcher is another, albeit rather complicated, method you could consider. I've no experience with one myself, but have read a good deal about them in some books I'll recommend to you: Handbook of Model Rocketry, G. Harry Stine (Bill Stine), available on Amazon. Tim Van Milligan had one too, quite a bit thinner, but a good read as well...name escapes me, google will help. And Mark Canepa (sp?) has a seminal tome out on high power...but that will have more about towers as Zeus-cat explained, and not pistons, since those are Low power only (to my knowledge and hope).
    NAR 96681
    L1 - May 29, 2014 LOC Norad ProMax, H120
    L2 - Feb 21, 2015 Fiberglassed Madcow Frenzy, J280

  5. #5
    Join Date
    14th March 2009
    Location
    Ohio
    Posts
    3,113
    Zeus-cat
    NAR# 92125 L1
    Total Impulse for 2017: 1,493.8 N/s Flights: 56
    2017: 1/2A:0, A:6, B:11, C:2, D:12, E:4, F:1, G: I have NEVER launched a G motor, H:1, I:1

  6. #6
    Join Date
    1st September 2010
    Location
    Tucson, AZ
    Posts
    1,037
    Quote Originally Posted by EliTheClasher View Post
    Do you have a picture of what it should look like?
    http://bfy.tw/COSc
    NAR 96681
    L1 - May 29, 2014 LOC Norad ProMax, H120
    L2 - Feb 21, 2015 Fiberglassed Madcow Frenzy, J280

  7. #7
    Join Date
    14th July 2015
    Location
    Randolph, NJ
    Posts
    2,948
    Flyaway guides?
    Recently completed: APRO Lander II and Starship Avalon; next up: Accur8-skinned Trajector and Ragnarok Orbital Interceptor
    My photo albums: fleet pics and OR Models

  8. #8
    Join Date
    1st September 2010
    Location
    Tucson, AZ
    Posts
    1,037
    you're much nicer than I am, and that's a good find- combination piston + tower!
    NAR 96681
    L1 - May 29, 2014 LOC Norad ProMax, H120
    L2 - Feb 21, 2015 Fiberglassed Madcow Frenzy, J280

  9. #9
    Join Date
    14th March 2009
    Location
    Ohio
    Posts
    3,113
    Quote Originally Posted by soopirV View Post
    you're much nicer than I am, and that's a good find- combination piston + tower!
    Yes I am.

    I didn't even notice that it had a piston. Pistons make a huge difference too, but are tricky if you don't know how to set one up.
    Zeus-cat
    NAR# 92125 L1
    Total Impulse for 2017: 1,493.8 N/s Flights: 56
    2017: 1/2A:0, A:6, B:11, C:2, D:12, E:4, F:1, G: I have NEVER launched a G motor, H:1, I:1

  10. #10
    Join Date
    21st May 2017
    Posts
    5
    Quote Originally Posted by Zeus-cat View Post
    For competitions our club uses launch towers. Essentially, the rocket sits in the middle of three rods that keep the rocket pointing up for the first meter of travel. They can be rather expensive as they are designed to be adjustable to handle rockets of many different diameters. If you are only making one for a specific rocket you could just use three or four rigid poles. Make sure you look at designs online and note that they all have something at the top or along the length of the rods to keep them rigid enough to keep the rocket trapped inside. Three rods stuck in the ground will NOT be sufficient.

    I assume you are not in the U.S. as you are using meters. You might want to look for a local club and see if they have a launch tower.

    Are you making your own motors too? That isn't something we talk about in the open forum for a number of reasons.
    Thanks for the help. I AM making my own motors and I knew there was a separate forum for it. Do you have a link to that? I cant find anything from this site. I am in the US I probably use meters just because I am used to it as a standard unit from AP Physics.

  11. #11
    Join Date
    30th January 2016
    Location
    US > OK > NE
    Posts
    3,116
    18+, Lvl1 cert w/ either NAR or TRA to be added to the research forum.

  12. #12
    Join Date
    14th March 2009
    Location
    Ohio
    Posts
    3,113
    I assume you are not a member of the Tripoli Rocketry Association. To make your own motors and launch them in a rocket at an organized event in the U.S. you need to be a member of Tripoli. You also need to be level 2 high power certified in that organization to make motors. However, you can do this on your own, but you will need to find a launch site and you won't be covered by any insurance. You also need to comply with FAA regulations. This is all MUCH easier if you are in Tripoli.

    Also, and most important, making motors can be VERY dangerous. It is best to learn how from someone that knows how to do it. Again, that is more easily accomplished if you are in a club and working towards high power certification.
    Zeus-cat
    NAR# 92125 L1
    Total Impulse for 2017: 1,493.8 N/s Flights: 56
    2017: 1/2A:0, A:6, B:11, C:2, D:12, E:4, F:1, G: I have NEVER launched a G motor, H:1, I:1

  13. #13
    Join Date
    6th June 2011
    Location
    San Diego, CA
    Posts
    869
    Don't let any of this discourage you. We do have a process for own-design motors, and many people are doing it successfully. But it will work much more smoothly if you get involved with a TRA club and get your level 2 certification. I would highly recommend getting started with commercial motors anyway, in order to get familiar with construction and flying of larger rockets, neither of which are trivial.
    Dave Cook
    NAR 21953 L3 - TRA 1108 - DART San Diego

  14. #14
    Join Date
    15th May 2016
    Posts
    1,903
    Fiberglass rods are not very rigid. You may see a benefit simply moving to a 1/4" stainless rod.

    Rail buttons and micro buttons are other options.

    a tower is of course, likely best.
    David McCann
    Dave's Rockets | My Flights
    URRG |URRF 4| Level 2 | TRA# 14210

  15. #15
    Join Date
    25th October 2016
    Location
    Texas, United States
    Posts
    1,641
    The Tim Van Milligan Book is called Model Rocket Design and Construction

  16. #16
    Join Date
    9th June 2010
    Posts
    88
    I don't know if this is the best approach, but it looks like you can buy assorted launch lugs on amazon for a reasonable price:
    https://www.amazon.com/Estes-302320-...ds=launch+lugs

  17. #17
    Join Date
    21st September 2017
    Location
    NY/NJ
    Posts
    73
    Quote Originally Posted by EliTheClasher View Post
    Hey all!

    I am working on a completely homemade rocket, and am wondering if there are any plausible alternatives to launch lugs. I currently use a simple fiberglass rod staked into the ground with a metal duct cover to protect the ground. It works well, but seems as though the system kills the velocity. In OpenRocket, estimates show that using launch lugs decreases my maximum velocity by about 30 m/s which is quite significant.

    Any advice appreciated!
    If you are seriously going for maximum height (competition?), then fly-away rail lugs are the way to go.
    More info (and videos) here:
    https://www.apogeerockets.com/Launch...ail-Guide-2-pk


    If you are primarily concerned with rocket stability on a wobbling launch rod (which you staked into the ground), there are a few things you can do to improve the situation:
    1). Invest into a proper launch pad. Something like this will work well up to 1/4" rods:
    http://www.hobbylinc.com/htm/aro/aro...BoCBvcQAvD_BwE
    2). Get a longer solid stainless still 1/4" rod (fiberglass is way too flexible) and use 1/4" lugs.
    3). For larger (HP) rockets, you have to go with rail buttons (e.g. 1010). To use these successfully you will either have to come out to local rocket club launch days, or buy your own "rail launcher".
    https://www.apogeerockets.com/Buildi...utton_Standard

    Quote Originally Posted by jpbell View Post
    I don't know if this is the best approach, but it looks like you can buy assorted launch lugs on amazon for a reasonable price:
    https://www.amazon.com/Estes-302320-...ds=launch+lugs
    That can work.
    You can get them even cheaper here:
    http://www.hobbylinc.com/estes-model...ug-pack-302320

    a


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