Earlier quoted context omitted.
On gliders, the airspeed indicator is even simpler - just a pitot tube connected to a (very sensitive) pressure gauge. The variometer (a vertical speed indicator) uses an internal air reservoir and a calibrated restriction to derive rate of climb or descent. So, all the main instruments (altimeter, airspeed, vario) are worked by atmospheric pressure, no batteries needed.
Modern variometers are more sophisticated than this. The first major modification was the total energy variometer, which takes account of the fact that you can trade speed for altitude and vice-versa. It gives a figure (expressed as an equivalent rate of climb) that corresponds to whether the sum of your potential and kinetic energy is increasing or decreasing. This is particularly useful in rough air, where, with a…
Re: Yaw String
#41Wow, a lot has happened since I dipped my feet into those waters. The lessons I took before my feet got too cold :-) were in old-school Schweizer ships (a 2-22 and a 2-33) with just the bare basics. Naturally, a yaw string was one of them.