Editing Variometer (section)

===Total energy compensation in practice===
[[File:Total Energy Variometer with Braunschweig Tube.jpg|thumb|300px|Total Energy Variometer with Braunschweig Tube]]
Total-Energy Variometers use a membrane compensator, compensation by [[venturi effect|venturi]], or are electronically compensated.  The membrane compensator is an elastic membrane, which flexes according to the total pressure (pitot plus static) from airspeed. Thus, airspeed effects cancel out an increase in sink, due to acceleration, or a decrease in sink, due to deceleration.  The venturi compensator supplies a speed-dependent negative pressure, so that the pressure reduces as speed increases, compensating for the increased static pressure due to sink.  According to [[Helmut Reichmann]], "...the least sensitive venturi mounting point would appear to be on the upper quarter of the vertical fin, some 60 cm (2 feet) forward of the leading edge."  Venturi compensator types include the [[Frank Irving|Irving Venturi]] (1948), the Althaus Venturi, the Hüttner Venturi, the Brunswick Tube, the Nicks Venturi, and the Double-Slotted Tube, developed by Bardowicks of [[Akaflieg]] Hannover, also known as the Braunschweig Tube.<ref name=hr/><ref name=faa/><ref>Nicks, Oran, A Simple Total Energy Sensor, NASA TM X-73928, March 1976</ref><ref>{{cite journal |last1=Brandes |first1=Tom |title=The Braunschweig Tube |journal=Soaring |date=1975 |volume=39 |issue=1 |pages=37–38 |publisher=Soaring Society of America}}</ref>

Very few powered aircraft have total energy variometers.  Pilots of powered aircraft are more interested in the true rate of change of altitude, as they often want to hold a constant altitude or maintain a steady climb or descent.