When I do a speed test I use the 3 leg process and putting the results into a spreadsheet to determine the accurate speed.
Last October I got TAS of 197 knots.
Today I got TAS of 193 knots.
The differences were - I was 100 PA feet lower today (7980), and it was 17* C colder (30.6* F colder) today. I was also slightly lighter today.
My question: Is it possible to calculate how much of the airspeed difference can be explained by the lower temperature and slightly lower elevation? Or should these things make a difference in airspeed?
My thinking: Colder air is denser therefore increases drag so I would go slower, but by how much?. Colder air is denser therefore should increase power (however MAP was the same - 22.6") so I would go faster, but by how much?
Note: My CAS error in both cases was less than a half knot (0.2 in Oct and 0.0 today).
Last October I got TAS of 197 knots.
Today I got TAS of 193 knots.
The differences were - I was 100 PA feet lower today (7980), and it was 17* C colder (30.6* F colder) today. I was also slightly lighter today.
My question: Is it possible to calculate how much of the airspeed difference can be explained by the lower temperature and slightly lower elevation? Or should these things make a difference in airspeed?
My thinking: Colder air is denser therefore increases drag so I would go slower, but by how much?. Colder air is denser therefore should increase power (however MAP was the same - 22.6") so I would go faster, but by how much?
Note: My CAS error in both cases was less than a half knot (0.2 in Oct and 0.0 today).