Monthly Archives: June 2011

Solving the point mass model of a dart’s trajectory, part two

I wrote a technical paper about solving these equations and made some conclusions for design. I have fully solved the flat-fire case given that the x velocity stays above a certain number (and it generally will). (Original link broken: My newer notes contain that paper and more.) The take-home message is pretty simple: Keep kinetic […]

boltsniper’s optimal barrel length formula

Whenever there is a thread about one of the holy grails of Nerf ballistics, an equation for the barrel length that maximizes performance, someone is bound to mention the results of some tests boltsniper did in 2005 when he was designing the FAR. boltsniper, for the uninitiated, is one of the few engineers in the […]

Solving the point mass model of a dart’s trajectory, part one

This blog post is relatively math heavy and it serves mostly as notes for my own use. I will assume some familiarity with differential calculus and ordinary differential equations. I also will assume some familiarity with the basic equations that govern the motion of Nerf darts after they leave the barrel. Yesterday I had an […]

Approximate expansion diameter of latex tubing

I previously wrote about how to estimate the expansion diameter of latex tubing, but I made no measurements to verify that the formula I suggested, where is the unexpanded inner diameter of the tube and is the unexpanded tube wall thickness, was accurate. Back in 2010, I made some measurements for tests that were aborted […]

Next two months

Sorry all, but I’ll be basically inaccessible for the next two months. At the moment I’m working at NIST with Randy McDermott and I’m staying at a hotel with terrible internet. I’ll see what I can do on weekends.