Cargo aircraft

A cargo aircraft (also known as freight aircraft, freighter, airlifter, or cargo jet) is a fixed-wing aircraft that is designed or converted for the carriage of goods, rather than passengers. Such aircraft usually do not incorporate passenger amenities, and generally feature one or more large doors for loading cargo. Freighters may be operated by civil passenger or cargo airlines, by private individuals or by the armed forces of individual countries. However most air freight is carried in special ULD containers in the cargo holds of passenger aircraft.

Aircraft designed for cargo flight usually have features that distinguish them from conventional passenger aircraft: a wide/tall fuselage cross-section, a high-wing to allow the cargo area to sit near the ground, a large number of wheels to allow it to land at unprepared locations, and a high-mounted tail to allow cargo to be driven directly into and off the aircraft.

History
Aircraft were put to use carrying cargo in the form of "air mail" as early as 1911. Although the earliest aircraft were not designed primarily as cargo carriers, by the mid-1920s aircraft manufacturers were designing and building dedicated cargo aircraft.

In Britain in the early 1920s, the need was recognized for a freighter aircraft to transport troops and materiel quickly to pacify tribal revolts in the newly occupied territories of the Middle East.

The Vickers Vernon, a development of the Vickers Vimy Commercial which was a passenger variant of the famous Vickers Vimy bomber therefore entered service with the Royal Air Force as the first dedicated troop transport in 1921.

In February 1923 this was put to use when Vernons of Nos. 45 and 70 Squadrons of the RAF's Iraq Command flew nearly 500 Sikh troops from Kingarban to Kirkuk in the first ever strategic airlift of troops. This operation conducted over a short range; it was not until 1929 that the RAF conducted a long-range non-combat air evacuation of British diplomatic staff from Afghanistan to India during the Kabul Airlift.

Vernons were replaced by Vickers Victorias from 1927 with 70 Squadron in Iraq and 216 Squadron in Egypt that year. Eight Victorias of 70 Squadron played an important part in the Kabul Airlift of November 1928–February 1929, when in severe winter conditions, RAF aircraft evacuated diplomatic staff and their dependents together with members of the Afghan royal family endangered by a civil war. Victorias were used to ferry troops to potential trouble spots including both in Iraq and elsewhere, flying reinforcements to Palestine in 1929 and Jordan in 1930 and from Egypt to Cyprus in 1931.

The Victorias of the two operational squadrons also made a number of long range training flights, such as return trips from Cairo to Aden in 1931, and helped to pioneer air routes for Imperial Airways' Handley Page HP.42 airliners. The Central Flying School converted one Victoria to be used as a blind flying, fitting it with two sets of controls and instruments in a blanked off cabin. The Victoria continued in service until 1935, although many were converted into Valentias, which remained in use until well into the Second World War.

The World War II German design, the Arado Ar 232 was the first purpose built cargo aircraft. The Ar 232 was intended to supplant the earlier Junkers Ju 52 freighter conversions, but only a few were built. Most other forces used freighter versions of airliners in the cargo role as well, most notably the C-47 Skytrain version of the Douglas DC-3, which served with practically every Allied nation. One important innovation for future cargo aircraft design was introduced in 1939, with the fifth and sixth prototypes of the Junkers Ju 90 four-engined military transport aircraft, with the earliest known example of a rear loading ramp. The conventional landing gear-equipped Ju 90 design pioneered the so-called Trapoklappe rear loading ramp to raise the fuselage to a level attitude as it deployed from underneath the rear fuselage, as it was powerful enough to do so, and a similar rear loading ramp even appeared in a somewhat different form on the nosewheel gear-equipped, late WW II era American Budd RB-1 Conestoga twin-engined cargo aircraft.

Postwar Europe also served to play a major role in the development of the modern air cargo and air freight industry during what became known as the "Cold War." It is during the Berlin Airlift at the height of this "Cold War," when a massive mobilization of aircraft was undertaken by the "free world," to supply West Berlin residents with food and supplies, in a virtual around the clock air bridge, after the Soviet Union closed and blockaded Berlin's borders, and land links to the west.

In the years following the war era a number of new custom-built cargo aircraft were introduced, often including some "experimental" features. For instance, the US's C-82 Packet featured a removable cargo area, while the C-123 Provider introduced the now-common upswept tail with - for the first time in combination, following the Budd RB-1's 1944 introduction of them together on an American cargo aircraft design - a drop-down rear cargo ramp, originally pioneered as the aforementioned Trapoklappe device on the German Ju 90 V5 and V6 prototypes. But it was the introduction of the turboprop that allowed the class to mature, and even one of its earliest examples, the C-130 Hercules, is still the yardstick against which newer military transport aircraft designs are measured.

When the Airbus A380 was announced, the maker originally accepted orders for the freighter version A380F, offering the second largest payload capacity of any cargo aircraft, exceeded only by the Antonov An-225. An aerospace consultant has estimated that the A380F would have 7% better payload and better range than the 747-8F, but also higher trip costs. However, as of February 2013, production has not started, and firm availability dates have not been announced.

Types of cargo aircraft
Nearly all commercial cargo aircraft presently in the fleet are derivatives or transformations of passenger aircraft. However, there are three other methods to the development of cargo aircraft.



Cargo aircraft as a derivative of a new or existing passenger or military airplane
Existing air cargo derivatives of passenger airplanes have been very fitting. For example, the Boeing-747-200F has proven to be the big payload toiler of the air cargo fleet and could continue unmodified for a number of years. Each derivative freighter has the benefit of having most of its development costs already assessed against the transaction of its passenger equivalent. Furthermore, the financial arrangements for buying the airplane have already been established and there is a quite short lead time before production (as compared to all new aircraft). A main drawback of existing air cargo aircraft is that they represent older technology; thus their direct operating costs are higher than what might be achieved with current technology. Additionally, since they generally have not been designed specifically for air cargo, loading and unloading can cause problems; the aircraft may be pressurized more than necessary, and there may be apparatus manufactured for passenger safety that is not necessary for cargo.

Cargo aircraft as development of a dedicated civilian cargo aircraft designed without regard for either passenger or military requirements
A dedicated commercial air freighter is an airplane which has been designed from the beginning as a freighter, with no restrictions caused by either passenger or military requirements. Over the years, there has been a dispute concerning the cost effectiveness of such an airplane, with some cargo carriers stating that they could consistently earn a profit if they had such an aircraft. To help resolve this disagreement, the National Aeronautics and Space Administration (NASA) selected two contractors, Douglas Aircraft Co. and Lockheed-Georgia Co., to independently evaluate the possibility of producing such a freighter by 1990. This was done as part of the Cargo/Logistics Airlift Systems Study (CLASS). At comparable payloads, dedicated cargo aircraft was said to provide a 20 percent reduction in trip cost and a 15 percent decrease in aircraft price compared to other cargo aircraft. These findings, however, are extremely sensitive to assumptions about fuel and labor costs and, most particularly, to growth in demand for air cargo services. Further, it ignores the competitive situation brought about by the lower capital costs of future derivative air cargo aircraft.

The main advantage of the dedicated air freighter is that it can be designed specifically for air freight demand, providing the type of loading and unloading, flooring, fuselage configuration, and pressurization which are optimized for its mission. Moreover, it can make full use of NASA’s ACEE results, with the potential of significantly lowering operating costs and fuel usage. Such a high overhead raises the price of the airplane and its direct operating cost (because of depreciation and insurance costs) and increases the financial risks to investors, especially since it would be competing with derivatives which have much smaller development costs per unit and which themselves have incorporated some of the cost-reducing technology.

Cargo aircraft as a development of a joint civil-military air cargo plane that would satisfy both commercial and military requirements
One benefit of a combined development is that the development costs would be shared by the civil and military sectors, and the number of airplanes required by the military could be decreased by the number of civil reserve airplanes purchased by air carriers and available to the military in case of emergency. There are some possible drawbacks, as the restrictions executed by joint development, the punishments that would be suffered by both civil and military airplanes, and the difficulty in discovering an organizational structure that authorizes their compromise. Some features appropriate to a military aircraft would have to be rejected, because they are not suitable for a civil freighter. Moreover, each airplane would have to carry some weight which it would not carry if it were independently designed. This additional weight lessens the payload and the profitability of the commercial version. This could either be compensated by a transfer payment at acquisition, or an operating penalty compensation payment. Most important, it is not clear that there will be an adequate market for the civil version or that it will be cost competitive with derivatives of passenger aircraft.

Today
Most conversions are carried out on older aircraft no longer suitable for passenger use, often due to changing safety or noise requirements, or when the aircraft type is considered to have become uncompetitive in passenger airline service, but there is also a market for new-build freighter designs. Freighter aircraft normally have strengthened cabin floors and the inclusion of a broad top-hinged door on the port fuselage in addition to an absence of passenger cabin windows which are "plugged."

The Boeing 747 can be ordered in a freighter version with a large nose door which could be raised above the cockpit for loading. The bulged top deck housing the cockpit was originally designed to allow an unobstructed main deck, and to keep cargo from crushing the pilots in the case of an accident. The interior size of the fuselage is matched to the size of a standard shipping container, stacked two high and two wide.

Other types of specialized civilian cargo aircraft configurations, include the swing-tail Canadair CL-44 and Boeing 747 Large Cargo Freighter, and the clamshell tail CASA CN-235.

Early air mail and airlift logistics aircraft
Important "airlift and logistics;" "cargo-liners," "mail-liners," and "mail aircraft."
 * Avro Lancastrian (Transatlantic mail)
 * Avro York (Berlin Airlift)
 * Boeing C-7000
 * Curtiss JN-4
 * Douglas M-2

Civilian cargo/freight aircraft

 * Aero Spacelines Pregnant Guppy
 * Aero Spacelines Super Guppy
 * Aero Spacelines Mini Guppy
 * Airbus A300
 * Airbus A310
 * Airbus A320 (Conversions)
 * Airbus A330
 * Airbus A380F
 * Airbus A300B4-608ST 'Beluga'
 * Antonov An-12
 * Antonov An-26
 * Antonov An-124 (the second largest operating cargo aircraft in the world)
 * Antonov An-225 (the largest and heaviest aircraft in the world)
 * British Aerospace 146QT (Conversions)
 * British Aerospace ATPF (Conversions)
 * Boeing 727 (Conversions)
 * Boeing 737 (Conversions)
 * Boeing 757
 * Boeing 767
 * Boeing 747 Freighter
 * Boeing 747-8 Freighter
 * Boeing 747 Large Cargo Freighter (Dreamlifter)
 * Boeing 777 Freighter
 * Douglas DC-3
 * Douglas DC-8
 * Douglas DC-9
 * Ilyushin Il-76
 * Ilyushin Il-96
 * Lockheed L-100
 * McDonnell Douglas DC-10
 * McDonnell Douglas MD-11
 * Tupolev Tu-204

Light aircraft

 * Cessna Caravan - freight door and belly pod equipped
 * Shorts 330 - drop ramp and twin tailed vertical stabilizer
 * LET 410

Military cargo aircraft
See: Military transport aircraft

Experimental cargo aircraft

 * Hughes H-4 Hercules ("Spruce Goose")
 * Lockheed R6V Constitution
 * LTV XC-142