Lockheed Flatbed
Encyclopedia
The Lockheed "Flatbed" was a proposed cargo aircraft
design from the 1980s that mounted large loads "in the open" on the back of the aircraft, similar to a flatbed truck
. The name "flatbed" was unofficial, a more formal name was never assigned. Although there was a fair amount of public information released about the design in the early 1980s, the design was never picked up by the US Air Force and disappeared by the mid-80s.
The Flatbed concept avoided these problems by designing the aircraft primarily for massing out, the most common problem. An airliner
-sized fuselage is all that is needed for this role. In the case when the aircraft was called upon to carry an oversized load, the cargo bay would be removed, and the cargo chained directly to the back of the aircraft, in the open. Although performance would be greatly degraded due to drag, this would be more than made up for on all the other flights where a more suitable fuselage size was being used.
In keeping with the flatbed concept, the aircraft was designed to sit low to the ground. Trucks would drive up to the aircraft and push their loads onto the back. The bed of the aircraft consisted of parallel I-beam
s as the primary load-carrying structure, with metal sheeting on the top to provide a smooth walking surface. Like most cargo aircraft, rollers could be raised through small holes cut in the bed to allow palletted loads to be rolled on and off without requiring a forklift.
In a conventional cargo aircraft the wing is high-mounted to keep the under-slung engines as far from the ground as possible. This avoids foreign object damage
(FOD) when operating from dirty runways or dirt airfields. This layout also demands that the fuselage be supported from the top, essentially hanging from the wing's spars. For the Flatbed this would not be appropriate because the loads would be carried on top of the aircraft, not hung under it, so Lockheed moved the wing to the low-mounted position similar to most airliner
s. In order to avoid FOD, the engines were placed above the wing on pylons, which is aerodynamically similar on a modern symmetrical wing planform.
Likewise, most cargo aircraft use some version of a T-tail
in order to leave the area at the end of the cargo bay "open" so trucks can approach it. This requires the tail to be high-mounted on the fuselage, so, as with the wings, this approach would not work on the Flatbed. Instead a large two-fin tail was used, extending outward from a point forward of the loading area, placing the rudders well to either side of the bed. In order to allow loading and unloading at the same time, the cockpit area at the nose of the aircraft could be rotated to the right, allowing trucks to approach both ends. The aircraft has a number of design features in common with the Lockheed L-1011
, most obviously the crew cabin and cockpit area, and the overall size and layout.
The patent application shows it carrying two tanks (looking more like M4 Sherman
s than anything modern), and they also released concept artwork displaying various truck-like palletted loads mounted in a similar fashion. In these cases a small aerodynamic fairing was placed behind the cockpit area, which is flat at the rear, turning it into a sort of "pod". In most cases cargo would be carried under a cargo fairing that extended from the cockpit all the way to the tail, turning it into a fairly conventional-looking design, if somewhat "skinny" compared to traditional cargo designs like the C-5 Galaxy
. Additionally, they proposed a passenger carrying module the same size as the cargo fairing. These modules could be unloaded as a single unit, sliding forward off the bed to a special-purpose truck.
Cargo aircraft
A cargo aircraft is a fixed-wing aircraft designed or converted for the carriage of goods, rather than passengers. They are usually devoid of passenger amenities, and generally feature one or more large doors for the loading and unloading of cargo...
design from the 1980s that mounted large loads "in the open" on the back of the aircraft, similar to a flatbed truck
Flatbed truck
A flatbed truck is a type of truck which can be either articulated or rigid. As the name suggests, it has an entirely flat, level 'bed' body with no sides or roof...
. The name "flatbed" was unofficial, a more formal name was never assigned. Although there was a fair amount of public information released about the design in the early 1980s, the design was never picked up by the US Air Force and disappeared by the mid-80s.
Design anbd development
Conventional cargo designs generally "mass out" before they "bulk out", meaning that they often fly mostly empty inside. In this case the aircraft is carrying around a large fuselage for no reason, adding mass and drag and thereby lowering performance. Nevertheless they need to have oversized cargo bays for the cases where they have to carry bulky loads, rare as these may be. Lockheed's patent states it best:- Historically, transport airplanes have generally been specifically designed to haul either cargo, passengers, or outsize cargo. ... Military cargo aircraft, such as the C-130 and C-141, are designed to haul cargo and some vehicles –but not outsize cargo such as tanks or bridge launchers. The C-5A can carry all militarily defined outsize cargo and large commercial vehicles. Some later military cargo airplanes can carry some outsize vehicles/equipment, but the price is paid in terms of carrying a large fuselage around for the few times such outsize cargo is actually carried. ... Thus an idea transport airplane is considered to be one which is designed to utilize one common airframe to carry passengers, cargo and outsize equipment.
The Flatbed concept avoided these problems by designing the aircraft primarily for massing out, the most common problem. An airliner
Airliner
An airliner is a large fixed-wing aircraft for transporting passengers and cargo. Such aircraft are operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an aircraft intended for carrying multiple passengers in commercial...
-sized fuselage is all that is needed for this role. In the case when the aircraft was called upon to carry an oversized load, the cargo bay would be removed, and the cargo chained directly to the back of the aircraft, in the open. Although performance would be greatly degraded due to drag, this would be more than made up for on all the other flights where a more suitable fuselage size was being used.
In keeping with the flatbed concept, the aircraft was designed to sit low to the ground. Trucks would drive up to the aircraft and push their loads onto the back. The bed of the aircraft consisted of parallel I-beam
I-beam
-beams, also known as H-beams, W-beams , rolled steel joist , or double-T are beams with an - or H-shaped cross-section. The horizontal elements of the "" are flanges, while the vertical element is the web...
s as the primary load-carrying structure, with metal sheeting on the top to provide a smooth walking surface. Like most cargo aircraft, rollers could be raised through small holes cut in the bed to allow palletted loads to be rolled on and off without requiring a forklift.
In a conventional cargo aircraft the wing is high-mounted to keep the under-slung engines as far from the ground as possible. This avoids foreign object damage
Foreign object damage
Foreign Object Debris is a substance, debris or article alien to a vehicle or system which would potentially cause damage.Foreign Object Damage is any damage attributed to a foreign object that can be expressed in physical or economic terms that may or may not degrade the product's required...
(FOD) when operating from dirty runways or dirt airfields. This layout also demands that the fuselage be supported from the top, essentially hanging from the wing's spars. For the Flatbed this would not be appropriate because the loads would be carried on top of the aircraft, not hung under it, so Lockheed moved the wing to the low-mounted position similar to most airliner
Airliner
An airliner is a large fixed-wing aircraft for transporting passengers and cargo. Such aircraft are operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an aircraft intended for carrying multiple passengers in commercial...
s. In order to avoid FOD, the engines were placed above the wing on pylons, which is aerodynamically similar on a modern symmetrical wing planform.
Likewise, most cargo aircraft use some version of a T-tail
T-tail
thumb|right|Grob motor gliderA T-tail is an aircraft tail stabilizer configuration in which the horizontal surfaces are mounted to the top of the vertical stabilizer. Traditionally, the horizontal control surfaces are mounted to the fuselage at the base of the vertical stabilizer...
in order to leave the area at the end of the cargo bay "open" so trucks can approach it. This requires the tail to be high-mounted on the fuselage, so, as with the wings, this approach would not work on the Flatbed. Instead a large two-fin tail was used, extending outward from a point forward of the loading area, placing the rudders well to either side of the bed. In order to allow loading and unloading at the same time, the cockpit area at the nose of the aircraft could be rotated to the right, allowing trucks to approach both ends. The aircraft has a number of design features in common with the Lockheed L-1011
Lockheed L-1011
The Lockheed L-1011 TriStar, commonly referred to as the L-1011 or TriStar, is a medium-to-long range, widebody passenger trijet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed...
, most obviously the crew cabin and cockpit area, and the overall size and layout.
The patent application shows it carrying two tanks (looking more like M4 Sherman
M4 Sherman
The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...
s than anything modern), and they also released concept artwork displaying various truck-like palletted loads mounted in a similar fashion. In these cases a small aerodynamic fairing was placed behind the cockpit area, which is flat at the rear, turning it into a sort of "pod". In most cases cargo would be carried under a cargo fairing that extended from the cockpit all the way to the tail, turning it into a fairly conventional-looking design, if somewhat "skinny" compared to traditional cargo designs like the C-5 Galaxy
C-5 Galaxy
The Lockheed C-5 Galaxy is a large military transport aircraft built by Lockheed. It provides the United States Air Force with a heavy intercontinental-range strategic airlift capability, one that can carry outsize and oversize cargos, including all air-certifiable cargo. The Galaxy has many...
. Additionally, they proposed a passenger carrying module the same size as the cargo fairing. These modules could be unloaded as a single unit, sliding forward off the bed to a special-purpose truck.