I have driven many miles with an automobile test rig consisting of a
pitot, a static and a TE probe connected to a pair of side by side
U-tube water manometers. The manometers share the same static and one
uses the pitot signal while the other uses the TE signal. A properly
calibrated TE probe will cause exactly the same pressure difference as
the pitot, just with the opposite sign.

I understand we need the TE probe to generate the difference
static-dynamic because classical instruments are pure mechanical and
need the TE information to compensate the vario. But given electronic
devices/computers, do we really need the TE probe at all? The
information is given, when static and dynamic pressure are known. The
rest can be calculated. Wrong?
Eggert

Eggert, right. You are correct and some electronic instruments do just that
- they take the pitot and the static (instead of static and TE) and subtract
them electronically, and it's not just mechanical instruments which use TE,
the B50 has three inputs: pitot, TE, and static.

A TE probe isn't the only way of compensating for airspeed changes, ancient
glider pilots used diaphrams to achieve the same thing.

I sent some notes to Eckhard yesterday relating to how you might try and
achieve the calculation in Cumulus.

Rgds,

Derrick.