On Tuesday, 11 August 2020 at 13:43:12 UTC+3, wrote:
On Tuesday, August 11, 2020 at 12:01:37 AM UTC-4, krasw wrote:
There seems to be a misconception about time constant of variometer. Many (all?) think that 2 sec time constant means that it takes 2 seconds after hitting thermal for variometer to show any lift. This is not true. Time constant means that within that time variometer needle reaches 100% of the pressure change signal. That does not mean that variometer needle does not start to show at least something (needle starts to rise) before that 2 secs.
What is the advantage of that 2 sec time constant, i.e. taking 2 seconds to reach 100% of the pressure change? Is the advantage that setting the time constant to a lower value (say, 1 sec or a half sec) means that the vario NEVER reaches 100% of the pressure change? i.e. you never get to know how good the thermal really is?

Ben Ethridge

If lower time constant would be better, then everyone would set electrical vario time constant to zero.

Adjusting time constant is just a tool to filter out gusts from TE signal. Amount of disturbances would depend on your glider pitot static system, TE-probe, plumbing, variometers connected and most importantly, your personal preference.

There is no right or wrong here. I have my inertial variometer tc is set to 1 sec, electrical to 5 sec, and mechanical somewhere between. They have all different settings, because way of measuring signal is profoundly different between instruments.