I happened across this pic this morning (with my coffee) and thought you folks like a little tale about it.
It’s a medical facility. A portable one. Treating casualties has long been a challenge for armies in the field, and operating out of tents has some drawbacks, sanitation being one of them. So a nice trailer like treatment facility is pretty handy.
Rather than designing a facility, and then using various prime movers to support it, in this case, the prime mover was built, and then the ideas of what it could move came along.
In the late 1950s, as the Army began to get into helicopters in a big way, and just as turbine engines with significant power were being developed, the Army realized it had a lot of stuff it wanted to move by helicopter that was never going to fit inside a helicopter. Sling loading external loads was an obvious answer. As the Army worked with Sikorsky to develop a heavy lift helicopter, it occurred to old Igor that there was no sense in putting a fuselage on the helicopter. Why lift the weight of the airframe if you didn’t need it? So eventually the CH-54 Tarhe was designed. It was an almost skeletal frame, with a pod like cockpit for the crew, a spine that mounted the rotors, and a tall gangly undercarriage.
But the Army also knew there would be times when it would be nice if they could carry stuff inside. Given that the CH-54 (almost never called the Tarhe, but instead the Skycrane) didn’t have an inside to put people and things in, the pod was developed. It was aerodynamic, easy to attach and detach and quite useful. Versions were made for troop carrying, the above field medical unit, and various other configurations, such as a portable headquarters.
In the event, CH-54s were so busy lifting heavy stuff externally that they didn’t use the pods all that much. There were enough CH-47 Chinooks in the inventory to handle most internal loads, and even most external loads. Only the really heavy stuff had to be slung under a Skycrane.
After Vietnam, the Skycranes were transferred to the Guard, where they soldiered on up to the early 1990s. I can still recall seeing a couple flying around in the Birmingham, AL area. Several are still in use today as firefighting platforms.