World War Two highlighted the value of air transport and also the need for dedicated military types. Experience with aircraft such as the C-47 and the Ju-52 (the most widely used military transports of the war) showed that often the key to success was not only rough field capability, but speed of turnaround. In some campaigns it was demonstrated that almost fifty percent of sortie time was spent loading and unloading. Over short haul distances this equated to requiring twice as many aircraft for a given load delivery capacity…in other words if loading and offloading could be speeded up half the number of aircraft could be used, or twice the amount of cargo could be delivered in a given period using the same number of aircraft.

The Ju 52 first flew in 1931 as a passenger liner. In 1935 a bomber version was secretly produced, forming the core of the Luftwaffe's bomber force. First used in action in the Spanish Civil War, it was then modified to the troop and freight role, in which it served throughout WW2.
Like the JU-52 the C47 began life as an airliner - the Douglas DC-3. Quickly adapted to the troop and cargo role, the C47 established a fine reputation during WW2. By the end of the war over 10,000 had been built.

The importance of this to logistic planners was significant. First it meant that sufficient supplies could be delivered to the battle-zone within the critical early phases of an operation. It also meant that for a given delivery factor over a short range (say 150 miles), that if half the number of aircraft could be used, the logistics support required to operate those aircraft would also be halved with a corresponding flow on effect back up the line.

What was needed was an easy load-unload method. The C-47 was modified with wide cargo doors, as was the Ju-52, however this was only a partial answer. Large loads still had to be dragged up ramps and fidgeted into place - often an awkward procedure on a sloping cargo floor with loads of different sizes and weights having to be distributed within the aircraft to keep the C of G within limits. The procedure then had to be repeated at the delivery end, either unloaded by hand or dropped by parachute. Often the standard delivery method for a C-47 despatcher(s) was to place the load at the door and then lay on his back and shove it out with his feet. Obviously this restricted the size of individual loads which could be dropped from the C-47.

Air dispatchers learned not only how to configure a cargo with parachutes and heave it from the aircraft at the right moment (in itself an artform) but by necessity also learned to use weight and balance tables to ensure correct cargo placement. Loading and unloading these aircraft became a physically intense operation - a C-47 could carry 6000lbs on a typical sortie, most of it having to shifted manually. Often crews became exhausted during intense operations, leading to tragic mistakes - either cargo shifting in flight or incorrect C of G placement. The evolution of the Air Dispatcher as a recognised skill is an interesting and often unsung story.

Experience showed what was needed was a method of "drive on, drive off" for pre-packed loads. Aircraft such as the C-47 and the Ju-52 were of course impossible to modify, so in the USA in 1942 design studies began, aimed at producing a specialised cargo aircraft. At first it was thought a quick and easy solution was to build gliders with the appropriate characteristics - ie flat cargo floor and easy access via front or rear loading doors. In the USA several glider designs were tried - some seeing action, while others such as the Chase Aircraft Corporation's glider which featured rear loading doors (later to become the C-123 "Provider") only reached the prototype stage.

Gigant powered by six radial engines

In Germany a bold concept was the Messerschmitt "Gigant" glider. This 95,000lb monster featured a cavernous cargo bay with drive on-off capability and a carrying capacity of almost 40,000lb. It was however, so big that it required two He 111s coupled via a harness system, plus two underwing rocket pods to get it airborne. Getting the beast into the sky proved such a dangerous task, that it was decided to convert it to a powered aircraft and so six radial 1000hp engines were added, making the "Gigant" the largest air freighter of the war. It played an important part in the German attempts to resupply Rommel's Africa Corps, but because it often flew unescorted it was vulnerable to fighter interception. Many brave crews were lost on these missions, however the Gigant was in many ways a forerunner of today's heavy lift military transports.

The British made use of several large troop and cargo carrying glider, the largest being the 44,000lb Hamilcar. This wood and fabric design could carry a small tank or sixty troops. It featured a side hinged nose and front loading. All gliders had limitations - the biggest being that they were usually only designed for one sortie, however they proved their worth in several campaigns including the Normandy landings.

One of the first purpose designed freighters was the Fairchild C-82 Packet. The aircraft was actually designed by the Kaiser Corporation, however during the construction of the prototype the company was taken over by Fairchild. This twin boom design flew in 1944 and entered service too late to see war service. Although the Packet turned out to be something of a "beast" to handle, it proved the value of its quick "load-unload" capability. The design was later developed into the C-119 "Flying Boxcar", of which more than a thousand were manufactured. Despite its 3,500hp engines the Boxcar tended to always be overloaded (a feature of military aircraft!) and suffered accordingly. However its usefulness can't be denied, and much valuable experience was gained by the Air Force and Army alike in the integration of cargo aircraft into the operational mix.

One of the most significant learning periods for air logistics planners came during the Berlin Airlift. In June 1948, the Soviets closed land access to west Berlin in an effort to force the allies to depart the city. The Russians calculated to supply the city by air would be impossible, as almost 4500 tons of material per day would be needed to keep the city functioning. Never had anyone done that before - including the Germans in their attempts to resupply their besieged troops at Stalingrad, where they'd barely managed 40 tons a day when everything was working in their favor. (vs 80 tons per day considered the minimum)

On the first day of the airlift US C-47s flew in 80 tons of supplies, reinforcing the Soviet belief that the attempt would soon collapse. However they didn't count on the rapid build up of the airlift support organisation and the might of the American logistic system. Using mainly USAF and RAAF crews, soon hundreds of aircraft were allocated to the task, with a strict air traffic control system being created. The route into Berlin from the west was on average about 120 miles from several fileds in the Western Zone. Assisted by ground control approach radar, (GCA) and new flight procedures an around the clock procession of aircraft began, allowing aircraft to land at three minute intervals the clock at four airfields in Berlin. As expertise increased the Soviets were shocked to find that not only was the tonnage delivered meeting the city's needs, but also reserve stockpiles were being created.

To help persuade the Soviets that it was in their best interest not to interfere with the streams of aircraft, the USAF deployed fighters and three B-29 squadrons within striking range of the Soviet Union - one of them the same squadron that dropped the A-Bomb on Hiroshima and Nagasaki, a subtle example of diplomacy that caught the nuclear deficient Soviets somewhat off guard.

The Berlin Airlift lasted ten months until June 1949 when the Soviets realised they were beaten. However supplies continued to be airlifted until September that year (at a lower rate) to build up reserves in the event of a change of heart by the Kremlin.

Valuable lessons were learned in the Berlin Airlift, the need for dedicated transport aircraft, with quick turnaround being one of them. WW2, the Berlin Airlift and the Korean War, laid the groundwork for the design of military transport aircraft as we know them today.