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Homework Help: Archived Rocket Launch Angle Question

  1. Sep 16, 2012 #1
    Hey everyone,

    I've been trying to do a problem in which I attempt to find the angle that maximizes the horizontal distance of a rocket, which has a stage with thrust and then a stage as a projectile. After a delay period, an ejection charge fires and causes the rocket to drop straight down. I want to have the ejection charge to fire before the rocket hits the ground, which means giving a bit of leeway.

    If any of you can look over my work and give me any suggestions, I would greatly appreciate it.

    1. The problem statement, all variables and given/known data

    Thrust: 3.42 N
    Burn Time (constant thrust assumed): .33s
    Delay time before ejection charge fires after burn time: 1.74s
    Mass: .033893kg

    Other values are calculated in the spreadsheet.

    2. Relevant equations

    Equations of motion/projectiles

    3. The attempt at a solution

    See spreadsheet. In it, I attempted to use the goal seek function to set the total time since burnout equal to the delay time (1.74s) by changing the value of the angle.

    Thanks for any ideas!

    Attached Files:

  2. jcsd
  3. Mar 7, 2016 #2


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    2017 Award

    Staff: Mentor

    The maximal distance will be reached if the rocket is just above the ground after 1.74 seconds. Safety factors can be added as necessary. Assuming a constant thrust vector, this leads to a quadratic equation for the vertical acceleration, which can be solved analytically.
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