Let’s See, What else could we put in it?
The C-5 was the first Jumbo-sized aircraft to be built and, unfortunately, the designers tried to include everything that anybody would ever want in a cargo aircraft.
It originally had a built-in weight & balance system that used strain gauges on the landing gear legs. The weight measured on each landing gear leg was used to determine the total weight of the aircraft while it sat on the ramp and then used the individual readings to calculate the actual aircraft center of gravity. Unfortunately, the system didn’t work quite the way that the engineers had intended. It seems that the computer logic was unable to adjust for uneven parking ramps and it was unable to understand why the readings kept changing when the aircraft was rocked by the wind. The system was eventually disabled.
Another of the capabilities that was designed into the plane was the ability to operate on “unprepared surfaces.” I remember hearing that the Edwards test pilots taxied the plane over dirt, gravel and stump-covered fields during the ground test phase. There was a system on the plane that allowed the crew to set a lower than normal tire pressure that would be suitable for the landing surface at their destination. They could take off from a normal runway and then, while in flight, decrease to tire pressure to the preset value for the landing. One of the sources listed below says that the system was then able to re-inflate the tires, but that wasn’t a capability of the system.
To take care of the re-inflation chore, the C-5 had a low pressure air compressor operated from the right forward main wheel well. The system used a turbo compressor powered by bleed air. It provided up to 150 psi air to be used to inflate the tires. Hoses and inflation fittings were stowed in a bin in the cargo compartment.
The ability to operate on unprepared surfaces was nice to have, but it would take major command approval to take the plane off-road. In normal operations, anyone letting a tire run off the pavement was risking their aircraft qualification and was almost assured of receiving “additional training.”
The most complicated system, however, was the landing gear.