# Monthly Archives: January 2011

## Computing the Age of the Universe

Introduction While in the lunch room at work, I often look at the paper. The paper one day this week had an article on the farthest object that has yet been observed by astronomers. One of the guys in my … Continue reading

Posted in Astronomy | 2 Comments

## Modeling Drag — Projectile Velocity Versus Range

Introduction As mentioned in a previous post, I am reading the book "Modern Practical Ballistics" by Pejsa. I have been working through some of the derivations in the book and they are interesting enough (at least to me) to be … Continue reading

Posted in Ballistics | 39 Comments

## Ogives Versus Other Shapes

The ogive has long been used in projectile design because it simple to manufacture. Over the last few thousand years, people have gotten pretty good at making sections of spheres. However, simple to manufacture does not mean minimum drag. The … Continue reading

Posted in Ballistics | 1 Comment

## Ogives and Battleships

Introduction The previous two blogs looked at the ogive shape and its use in describing bullet shapes. While cruising around the web, I noticed a rather large ogive shape that I thought was interesting. I am a big fan of … Continue reading

Posted in Ballistics | Tagged , | 4 Comments

## Ballistics, Ogives, and Bullet Shapes (Part 2)

Example One: Sierra 308 Caliber, 155 grain, MatchKing. We will first compute the mass for the Sierra MatchKing projectile (tangent ogive) shown in Figure 10. Observe that this projectile has a flattened nose, called a meplat. Because of the meplat, … Continue reading

Posted in Ballistics | 6 Comments

## Ballistics, Ogives, and Bullet Shapes (Part 1)

Introduction I have always been interested in the shooting sports, but I have not pursued any of them while I was raising my kids. I suddenly find myself with my kids gone and my interest in shooting has reappeared. As … Continue reading

Posted in Ballistics | 19 Comments

## Pope Gregory XIII and Dual Modulus Counters

I discussed a recent dual-modulus counter design in a previous post. I had not thought much about the history of these counters, but I noticed that our calendar is really a dual-modulus counter. Pope Gregory XIII (Figure 1) established the Gregorian calendar (1582) to resolve issues with the Julian calendar. The reason that calendar development is complicated is because a solar year is 365.24219879 days long, which is not easily expressed in terms of simple integer ratios. Ideally, a calendar system is chosen that is simple and that has a mean year length exactly equal to that of a solar year. While not ideal, the Gregorian calendar provides a simple and fairly accurate approximation to a solar year through the use of a dual-modulus counter design based on years with durations of 365 and 366 days. Continue reading

Posted in Astronomy, Electronics | Tagged , | 1 Comment

## The Difficulties Posed By Communications

My company currently has engineering work occurring at a number of sites that are widely separated geographically. Trying to coordinate these sites is definitely a challenge. However, this really is nothing new. When I was at HP, my first manager used to say that "Engineering communication reduces by 10 dB per foot." Continue reading