The Density Altitude Performance computer shows the aircraft's rate of climb and minimum-required takeoff distance. Anodized aluminum discs. 3-3/4" dia.
Important: Always consult your pilot's operating handbook as their computer does not supplement or replace the manufacturer's performance data. Not applicable to turbocharged aircraft.
This is small, only 3 1/2 across. Its all metal, and sturdily built. The disks are a bit stiff to move around at first, but they loosen up. One side (not pictured in the photo) is the typical circular-slide-rule part of an E6-B, for solving time/distance/speed/fuel problems, converting litres to gallons or knots to statute miles, calculating true altitude and airspeed, etc. etc. The other side (pictured), where the wind triangle would normally be on an E6-B, is a simple take-off-distance and climb-rate calculator. It calculates the multiplier, and then you apply that to the sea-level figure from your POH or AFM. The photo shows OAT in Celsius, but the one Aircraft Spruce shipped to me is calibrated in Fahrenheit, which is a big annoyance (but too cheap to be worth the hassle shipping back for a refund). If you care about the temperature units, add a note asking Spruce to confirm before shipping, because there are obviously two versions.