twotoes02

Wow fast responses, that's awesome! I do apologize for confusing you, its most likely in my clunky communication skills... Jason if I may, Let's assume the rocket is already in space and I'm using this derivation to determine the delta v needed for an orbital maneuver. I derived this equation from William Tyrrell Thomson's "Introduction to Space Dynamics" equation (8.1-10) on page 242 of the second edition (I believe its the second edition...). Now knowing this, if you believe TWR is not needed under these circumstances then we can certinally modify the equation or find another derivation that will serve my purpose better. And it seems that I may have not posted my question clearly. Please allow me to restate the question. Is it possible to rewrite the equation to solve for mbo knowing delta v, and the other variables? Or is there another derivation that would better suit my purpose. However, it seems that nyrath may have answered my question. nyrath, yes I certainly do understand the natural log and its opposite, the problem here is that one iteration of mbo is within a natural log and the other is not. I am a little confused unfortunately, you stated that R represents the mass ratio where the texts I have at hand show R as the thrust to weight ratio. Written as R = T/(m*g) where T is the thrust of the rocket. However it seems you have provided me another equation that will better suit me and my need! I do thank you good sir, please allow me to try this out and I will let you know if this is the answer I am looking for. Thank you for your time. I'll see if this answer is what I'm looking for.

Hey gang, Two Toes here. I was hoping to get some help with a bit of rocket science I've tripped up on. I'm trying to calculate the mass fraction of fuel a rocket will need to carry based on the needed delta v and a few other variables. Let me show you what I have so far: This derivation provides the delta v available for a single stage rocket knowing g, the specific impulse of the engine, the starting mass (mo), the burn out mass (mbo) and the thrust to weight ratio R. What I'd like to do (and this is where I'm having trouble) is redefine the equation in terms of mbo. With this I can determine the mass fuel fraction (mff) of the vessel knowing the thrust, specific impulse, delta v and starting mass. The issue as you can see is that one of the mbo's is located within a natural log. Does anyone know of another derivation that allows me to calculate the burn out mass with these (or more) variables? Other suggestions are more than welcome of course. Thanks!