Category Archives: Rocket Design Theory

Random Thought: “Sufficiently Advanced” Propulsion Technology

In many discussions of rocket technology, a skeptic will often make some comment about how things would be so much better if we had Warp Drive. But the reality is that we don’t really need Warp Drive for things to … Continue reading

Posted in Rocket Design Theory, Technology | 14 Comments

SSTO is a bad idea, but NTR SSTO is worse

A few months ago, I spent some time describing some calculations of payload fraction that I derived to assist in the design of rocket vehicles. My motivation for getting into this type of work came about from my work on … Continue reading

Posted in Rocket Design Theory | 31 Comments

Payload Fraction Calculation for Reusable Vehicles

When I was learning how to use mass-estimating relationships (MERs) at Georgia Tech, our focus was on reusable launch vehicles, and most of our MERs came from NASA Langley, where my professor had once worked. When it came to much … Continue reading

Posted in Rocket Design Theory | 7 Comments

Payload Fraction Example Proof

Continuing with our story from last time… The next day, your boss pokes his head in your office and asks: “How’s those forty trans-Mars injection stages going?” He notices that you’re checking out scuba-dive sites in the Caribbean for your … Continue reading

Posted in Rocket Design Theory | 62 Comments

Using Payload Fraction Expressions in an Example

Now that I’ve gotten the math and derivations out of the way, let’s us the payload fraction expressions in a real-world example. Let’s say you work for the chief technologist of NASA, and he’s thinking about sending humans to Mars. … Continue reading

Posted in Rocket Design Theory | 47 Comments

Calculating Gross-Mass-Sensitive Term

In the last post, I attempted to calculate a basic expression for the propellant-mass-sensitive term (lambda) and in this one I will attempt to do the same thing for the gross-mass-sensitive term (phi). In so doing, I will hopefully be … Continue reading

Posted in Rocket Design Theory | 3 Comments

Calculating Propellant-Mass-Sensitive Term

In my last two posts I’ve been talking about calculating payload fraction of a rocket using the mass ratio from the rocket equation and some vehicle parameters that have been sensitive to propellant mass and gross mass. To use these … Continue reading

Posted in Rocket Design Theory | 4 Comments

Payload Fraction Accounting for Gross-Mass-Sensitive Term

As I prepared for this post tonight, I realized that I wasn’t really modifying the rocket equation at all–I have been using the rocket equation and a summation of mass terms to find the payload fraction, which I consider an … Continue reading

Posted in Rocket Design Theory | 2 Comments

A Simple Modification of the Rocket Equation

When I was an undergrad, I spent two summers interning on the X-33 program at the Lockheed Martin Skunk Works in Palmdale, California. It was a fantastic experience and I got to meet with and work with some wonderful people … Continue reading

Posted in Rocket Design Theory | 12 Comments