Author Archives: Kirk Sorensen

About Kirk Sorensen

MS, nuclear engineering, University of Tennessee, 2014, Flibe Energy, president, 2011-present, Teledyne Brown Engineering, chief nuclear technologist, 2010-2011, NASA Marshall Space Flight Center, aerospace engineer, 2000-2010, MS, aerospace engineering, Georgia Tech, 1999

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 initial-mass-sensitive term (phi). In so doing, I will hopefully be … Continue reading

Posted in Rocket Design Theory | 4 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 | 5 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

Recursive Algorithm for Moravec’s Mass Ratio

Computing the mass ratio for a tapered tether (tether mass/tip mass) was first done (to the best of my knowledge) by Hans Moravec in an appendix to his unpublished 1978 paper, “Non-Synchronous Orbital Skyhooks for the Moon and Mars with … Continue reading

Posted in Space Tethers, Space Transportation, Technology | 9 Comments

Momentum Exchange Tethers — Early History

The history of momentum-exchange tethers goes back many, many years but is bound by a common thread that, until recently, limited the realization of this technology. That common thread is the need for high specific tensile strength. The first idea … Continue reading

Posted in Space Tethers, Space Transportation, Technology | 5 Comments

A Tether Technology Anniversary

Rotating momentum-exchange tethers are a very exciting technology, but one of my first thoughts after being exposed to the technology was the tricky rendezvous. The space industry has spent all kinds of money and time on satellite rendezvous, and these … Continue reading

Posted in Space Tethers, Space Transportation, Technology | 8 Comments

MXER Tether Intro #1: Simple Untapered Tethers

So I’ve started out telling you that momentum-exchange tethers are great. Why? you might ask. Well, because a spinning momentum-exchange tether is capable of transferring a fair fraction of the orbital energy and angular momentum in its orbit to a … Continue reading

Posted in Space Tethers, Space Transportation, Technology | Leave a comment

Momentum Exchange Tethers — An Introduction

Anyone who’s interested in going to the Moon ought to take a serious look at the technology of momentum-exchange tethers. My own interest began back in 1998, when as a summer intern on the X-33 program at Lockheed Martin Skunk … Continue reading

Posted in Space Tethers, Space Transportation, Technology | 10 Comments