Rocket Equation with varying gravity

  • Thread starter Rudipoo
  • Start date
  • #1
32
0
So, the rocket equation is

F_ext = m(dv/dt) + u(dm/dt)

where m is the mass of the rocket, v the velocity, u the effective exhaust gases speed, and F_ext the external forces on the system.

If we take a constant mass ejection rate p, and take the external force to be the gravitational attraction of a mass M, we recover the differential equation

(d^2x/dt^2) + GMx^(-2) = up/(m0 - pt)

where m0 is the initial mass (time t=0).

Can this type of differential equation be solved analytically? If so, how would one go about it?

Thanks,

Rudipoo
 

Answers and Replies

  • #2
Nabeshin
Science Advisor
2,207
16
Almost positive it's not solvable analytically, seeing as it's 2nd order non-linear. A quick run through mathematica seems to support that.
 

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