I stopped in to Penny Lane Records to see if they still had Cedar Rapids. After being reminded about it on Thursday, it’s a good chance to get it to enjoy again, and as preparation for showing it to others as well.

Airspeed Velocity


I was reminded today about the airspeed velocity of an unladen swallow. The popular formula for that doesn’t actually answer the question, but only gives rise to even more questions.

The formula is taken directly from that which is used for aircraft, to calculate the calibrated airspeed from impact pressure from the impact pressure on the airspeed indicator capsule of the aircraft, where:

  • A0 is the speed of sound at 15 degrees celsius
  • Qc is the impact pressure, and
  • P0 is the standard pressure at sea level.

Which doesn’t help much at all. How are we going to use an aircraft to follow an unladen swallow?

swallow_st13So, there are actually better ways of obtaining a result, from Estimating the Airspeed Velocity of an Unladen Swallow, which results in a nicely calculated formula of 24 miles an hour.