WWhiskey is correct. There is no key to return to default climb speed; you must know what the default climb speed is before changing it, and then manually re-enter the default climb speed to go back to it using the " .speed " command. And, as Karnak found out, it does revert to the default speed after you end that sortie, but not before.
To find out what the default speed is on climb-out, engage Auto-Speed (ALT X), let the aircraft fly stable for a few seconds, open the E6B and read the " indicated " airspeed. What you read as " indicated " is the default climb speed.
Another thing to know is that if you have re-set the default climb speed to another speed, and you re-arm using the re-arm pad, and you do not revert to the default climb speed manually, it will remain set at whatever setting you put it at. So when taking off after re-arming and you forget that you reset the default climb speed, and you engage auto speed, it will happily comply, go nose down to gain air speed, and potentially fly you into the ground.
