Just found this.
The X 15 photo with the pilot on the right scratching his ass is priceless !!
The truth is both the full pressure suits and the old ventilated wet suits (cold water survival) were completely air tight, and sweating in them was a real problem. Fortunately the aircraft ventilation systems provided a hookup for forced airflow with cooled air. Unfortunately, in most jet aircraft the ventilation system doesn't kick in until the engine is revved up past about 50% max RPM - that meant no air flow until takeoff.
The A-4 was particularly bad in this area, and, to make matters worse, it had a very small, cramped cockpit. Few things in life are as good as that first blast of refrigerated air up your ass as you advanced the throttle on the catapult after 30 minutes sweating like a stuck pig on the flight deck. It also made for exciting cat shots.