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  1. #1
    Join Date
    5th April 2018
    Location
    Buffalo, MN
    Posts
    9

    Question how to simulate railbutton in RockSim

    Hello all, I have search here and on the Apogee site, but don't see any info on how people simulate the aero affects of 1010 rail buttons on a flight. I know I can add a mass object, but I am wondering if anybody is using a method of modeling rail buttons that will change the aerodynamics of the rocket. I have played around with a launch lug with .01mm inside diameter (can't be zero), but hope to find a more accurate simulation. Thanks.

    Greg
    Robot-Engineer.com
    NAR # 105130 L0
    TRA # 17953 L0
    Currently building L1 - Mad Cow Super DX3 Fiberglass

  2. #2
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,872
    There are a couple methods. The one I use is this. I calculated the frontal area of the rail guide, and made a solid tube of the same area. It is not exact, but will get you close.

    The other method would to build a subassembly likely using pods.

    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Member of the Tripoli Motor Test Committee, and keeper of the motor file

  3. #3
    Join Date
    7th June 2011
    Posts
    115
    Quote Originally Posted by Robot-Engineer View Post
    Hello all, I have search here and on the Apogee site, but don't see any info on how people simulate the aero affects of 1010 rail buttons on a flight. I know I can add a mass object, but I am wondering if anybody is using a method of modeling rail buttons that will change the aerodynamics of the rocket. I have played around with a launch lug with .01mm inside diameter (can't be zero), but hope to find a more accurate simulation. Thanks.
    You can import the RockSim file into RASAero II. (See Pages 39-42 of the RASAero II Users Manual for importing RockSim files). RASAero II has an accurate Rail Guide drag model. Many of the rockets on the Comparisons with Altitude Data page on the RASAero web site have Rail Guides.

    http://www.rasaero.com/comparisons-alt.htm

    When you import the RockSim file into RASAero II, you'll have to make sure to update the Fin Airfoil data for your rocket. RASAero II has additional Fin Airfoils not available in RockSim, another thing that will give you increased accuracy for your altitude predictions.


    Charles E. (Chuck) Rogers
    Rogers Aeroscience

  4. #4
    Join Date
    18th March 2009
    Location
    Wisconsin
    Posts
    3,872
    The other way is to download Bruce Levinsonís assemblies for rail guides. Have copied right here username and password are both guest.

    http://rocketryfiles.com/?p=home&d=F...esign%20Files/
    Mark Koelsch
    Tripoli 6155 L3
    Owner of http://www.rocketryfiles.com/
    Editor of http://www.thrustcurve.org/
    Member of the Tripoli Motor Test Committee, and keeper of the motor file

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