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  1. #1
    Join Date
    2nd January 2013
    Posts
    208

    Can someone sim my Vulcanite, please?

    Rocket is a Loc Vulcanite H76, 38mm. Ill be using an AT I500-14. Rocket reviews has the CP at 46.32" from front. Weight is 28oz without motor. CG is 28 7/8" from front. Aeropac retainer extends out 15/16". Length is 53 1/2" just in case. Anything else needed?

    Ive launched it on a G64 and it was straight as an arrow, but may try the big boy motor this weekend! Thankyou.


  2. #2
    Join Date
    18th January 2016
    Location
    St. Louis
    Posts
    869
    You're going to hit mach 1.3 with that. Is it fiberglassed, or the stock LOC tubing?

    Mark
    NAR#: 100890 / TRA#: 16580
    L1 - Binder Design Excel Plus 38 - CTI I242 2,540'
    L2 - Binder Design Excel Plus 38 - CTI J330 3,672'
    L3 - Scratch built 8" PAC-3 MSE Patriot - Loki M1969 (ETA MWP 15)

  3. #3
    Join Date
    26th October 2009
    Location
    Sheboygan WI
    Posts
    1,221
    Here you go. Entered your info, YMMV with other conditions, but 14 sec delay good, stability good.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    _______________________
    Jeff - NAR #76531 -L2

  4. #4
    Join Date
    18th January 2016
    Location
    St. Louis
    Posts
    869
    Running quick numbers on my calc, your airframe will buckle.

    Axial Load Limit: 414 pounds force point where tube will crush
    Euler Buckling Limit: 66 pounds force point where tube will buckle

    On an AT I500:

    Total Compression Force: 122 pounds force Warning: Tube will buckle!

    You're more than 2x beyond the theoretical load limit of that airframe.
    Mark
    NAR#: 100890 / TRA#: 16580
    L1 - Binder Design Excel Plus 38 - CTI I242 2,540'
    L2 - Binder Design Excel Plus 38 - CTI J330 3,672'
    L3 - Scratch built 8" PAC-3 MSE Patriot - Loki M1969 (ETA MWP 15)

  5. #5
    Join Date
    2nd January 2013
    Posts
    208
    Ok thanks guys. Some things to think about.

  6. #6
    Join Date
    13th February 2016
    Location
    Gilroy, CA
    Posts
    568
    Quote Originally Posted by mccordmw View Post
    Running quick numbers on my calc, your airframe will buckle.

    Axial Load Limit: 414 pounds force point where tube will crush
    Euler Buckling Limit: 66 pounds force point where tube will buckle

    On an AT I500:

    Total Compression Force: 122 pounds force Warning: Tube will buckle!

    You're more than 2x beyond the theoretical load limit of that airframe.
    Interesting conversation.

    The 66lb buckling limit doesn't look good.

    Does the Total Compression Forces calculation assume that all motor thrust is acting through the airframe tube?

    I'm thinking that near burnout, but when the I500 is still producing ~550N or ~122 lbs of thrust, a good portion of that thrust will be acting against drag forces from the fins and base etc, and still some force will be acting to accelerate the rocket. Anyone know roughly what the nosecone and half the airframe tube's drag components would be in the transonic range? It would be interesting to see individual drag components are through the motor burn.

  7. #7
    Join Date
    18th January 2016
    Location
    St. Louis
    Posts
    869
    Quote Originally Posted by kevinkal View Post
    Interesting conversation.

    The 66lb buckling limit doesn't look good.

    Does the Total Compression Forces calculation assume that all motor thrust is acting through the airframe tube?

    I'm thinking that near burnout, but when the I500 is still producing ~550N or ~122 lbs of thrust, a good portion of that thrust will be acting against drag forces from the fins and base etc, and still some force will be acting to accelerate the rocket. Anyone know roughly what the nosecone and half the airframe tube's drag components would be in the transonic range? It would be interesting to see individual drag components are through the motor burn.
    Here's the link to the calc.

    https://drive.google.com/open?id=1cG...kY2F8sNV7NQd8k

    Oops. It's experiencing 100 lb force, not 122. I usually add in the drag from the nose through the body tube to get an estimate. The acceleration the max vel. and drag are the key factors in calculating force.

    The resources tab on the calculator shows where I derived all my formulae.
    Mark
    NAR#: 100890 / TRA#: 16580
    L1 - Binder Design Excel Plus 38 - CTI I242 2,540'
    L2 - Binder Design Excel Plus 38 - CTI J330 3,672'
    L3 - Scratch built 8" PAC-3 MSE Patriot - Loki M1969 (ETA MWP 15)

  8. #8
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,465
    Quote Originally Posted by mccordmw View Post
    Running quick numbers on my calc, your airframe will buckle.

    Axial Load Limit:414pounds forcepoint where tube will crush
    Euler Buckling Limit:66pounds forcepoint where tube will buckle

    On an AT I500:

    Total Compression Force:122pounds forceWarning: Tube will buckle!

    You're more than 2x beyond the theoretical load limit of that airframe.
    I do believe your numbers, while they might be correct, are not reality. I flew a Vulcanite a lot on a variety of motors and never saw buckling of any sort.


    Sent from my iPhone using Rocketry Forum
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Keeper of the motor files

  9. #9
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,465
    Quote Originally Posted by ascastil View Post
    Ok thanks guys. Some things to think about.
    I flew an I435 in mine at one time- survived. Flew a J420 too. Just saying that there was no damage. It was pretty heavily built.


    Sent from my iPhone using Rocketry Forum
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Keeper of the motor files

  10. #10
    Join Date
    8th September 2015
    Posts
    50
    On 10/20 I flew my un-glassed Vulcanite on a 38mm J570W to 8000'. Didn't build it in any special way, just followed the directions and used BSI epoxy. Eggtimer data recorded a speed of ~1.5 Mach (filtered, not raw). So yes, YMMV...

  11. #11
    Join Date
    19th February 2017
    Location
    The world, probably
    Posts
    288
    From what I understand, most of the strength in a BT is vertical- I think I saw someone test a stock BT-55 to well over 100lb. However, if you're really pushing the tube have a bit of wiggle, it'll fold. No idea what that means for this rocket- it's just that compression strength doesn't matter as much as stiffness in most cases, so a tighter NC fit, longer avbay coupler or some such thing might improve your strength by keeping the rocket more in line.

    Just my ... Not much experience with high performance stuff myself, just speaking from what I've seen on the forum.
    NAR #104043

    crmrc.org

  12. #12
    Join Date
    10th February 2013
    Location
    Fremont, CA
    Posts
    341
    Using Open Rocket set up for my 31 oz empty Vulcanite, an I500 launch would result in 61mph off the pad, 830mph max velocity, 36.5g max acceleration and 5,648 ft altitude at apogee. Sounds wicked.

    With no tracker at the time, my Vulcanite G-I motor flights were pretty tame. The I49N took it very slowly to 5,549 feet and I was lucky to recover it. The kit was built stock. Build here: http://www.rocketryforum.com/showthr...uild-challenge.

    Good luck and tell us the results!
    NAR TRA BAR L2

  13. #13
    Join Date
    2nd January 2013
    Posts
    208
    An I49 sounds interesting. I havent tried dual deploy yet. Ive got an Eggfinder and Chute release in mine. Im going to give this thing a shot on the I500 Sunday. One guy at my launch last weekend said itll be fine, another guy said it should be fine. We"ll see.....

  14. #14
    Join Date
    2nd January 2013
    Posts
    208
    Well, it worked! That thing went so high, wish I had an altimeter. Definitely am liking the rockets that fly high. That was a first for me for that sorta altitude.


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