Payload

Last updated

Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of the flight or mission, the payload of a vehicle may include cargo, passengers, flight crew, munitions, scientific instruments or experiments, or other equipment. Extra fuel, when optionally carried, is also considered part of the payload. [1]

Contents

In a commercial context (i.e., an airline or air freight carrier), payload may refer only to revenue-generating cargo or paying passengers. [2] A payload of ordnance carried by a combat aircraft is sometimes alternatively referred to as the aircraft's warload.

For a rocket, the payload can be a satellite, space probe, or spacecraft carrying humans, animals, or cargo. For a ballistic missile, the payload is one or more warheads and related systems; their total weight is referred to as the throw-weight.

The fraction of payload to the total liftoff weight of the air or spacecraft is known as the "payload fraction". When the weight of the payload and fuel are considered together, it is known as the "useful load fraction". In spacecraft, "mass fraction" is normally used, which is the ratio of payload to everything else, including the rocket structure. [3]

Relationship of range and payload

Payloadrange.jpg

There is a natural trade-off between the payload and the range of an aircraft. A payload range diagram (also known as the "elbow chart") illustrates the trade-off.

The top horizontal line represents the maximum payload. It is limited structurally by maximum zero-fuel weight (MZFW) of the aircraft. Maximum payload is the difference between maximum zero-fuel weight and operational empty weight (OEW). Moving left-to-right along the line shows the constant maximum payload as the range increases. More fuel needs to be added for more range.

The vertical line represents the range at which the combined weight of the aircraft, maximum payload and needed fuel reaches the maximum take-off weight (MTOW) of the aircraft. If the range is increased beyond that point, payload has to be sacrificed for fuel.

The maximum take-off weight is limited by a combination of the maximum net power of the engines and the lift/drag ratio of the wings. The diagonal line after the range-at-maximum-payload point shows how reducing the payload allows increasing the fuel (and range) when taking off with the maximum take-off weight.

The second kink in the curve represents the point at which the maximum fuel capacity is reached. Flying further than that point means that the payload has to be reduced further, for an even lesser increase in range. The absolute range is thus the range at which an aircraft can fly with maximum possible fuel without carrying any payload.

Examples

Examples of payload capacity:

Structural capacity

For aircraft, the weight of fuel in wing tanks does not contribute as significantly to the bending moment of the wing as does weight in the fuselage. So even when the airplane has been loaded with its maximum payload that the wings can support, it can still carry a significant amount of fuel.

Payload constraints

Launch and transport system differ not only on the payload that can be carried but also in the stresses and other factors placed on the payload. The payload must not only be lifted to its target, it must also arrive safely, whether elsewhere on the surface of the Earth or a specific orbit. To ensure this the payload, such as a warhead or satellite, is designed to withstand certain amounts of various types of "punishment" on the way to its destination. Most rocket payloads are fitted within a payload fairing to protect them against dynamic pressure of high-velocity travel through the atmosphere, and to improve the overall aerodynamics of the launch vehicle. Most aircraft payloads are carried within the fuselage for similar reasons. Outsize cargo may require a fuselage with unusual proportions, such as the Super Guppy.

The various constraints placed on the launch system can be roughly categorized into those that cause physical damage to the payload and those that can damage its electronic or chemical makeup. Examples of physical damage include extreme accelerations over short time scales caused by atmospheric buffeting or oscillations, extreme accelerations over longer time scales caused by rocket thrust and gravity, and sudden changes in the magnitude or direction of the acceleration caused by how quick engines are throttled and shut down, etc. Electrical, chemical, or biological payloads can be damaged by extreme temperatures (hot or cold), rapid changes in temperature or pressure, contact with fast moving air streams causing ionization, and radiation exposure from cosmic rays, the van Allen belt, or solar wind.

See also

Related Research Articles

<span class="mw-page-title-main">Rocket</span> Vehicle propelled by a reaction gas engine

A rocket is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the vacuum of space. Rockets work more efficiently in a vacuum and incur a loss of thrust due to the opposing pressure of the atmosphere.

<span class="mw-page-title-main">Single-stage-to-orbit</span> Launch system that only uses one rocket stage

A single-stage-to-orbit (SSTO) vehicle reaches orbit from the surface of a body using only propellants and fluids and without expending tanks, engines, or other major hardware. The term usually, but not exclusively, refers to reusable vehicles. To date, no Earth-launched SSTO launch vehicles have ever been flown; orbital launches from Earth have been performed by either fully or partially expendable multi-stage rockets.

<span class="mw-page-title-main">Mass driver</span> Proposed spacelaunch method

A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. Existing and contemplated mass drivers use coils of wire energized by electricity to make electromagnets, though a rotary mass driver has also been proposed. Sequential firing of a row of electromagnets accelerates the payload along a path. After leaving the path, the payload continues to move due to momentum.

A liquid air cycle engine (LACE) is a type of spacecraft propulsion engine that attempts to increase its efficiency by gathering part of its oxidizer from the atmosphere. A liquid air cycle engine uses liquid hydrogen (LH2) fuel to liquefy the air.

<span class="mw-page-title-main">Lifting body</span> Aircraft configuration in which the fuselage produces significant lift

A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating non-lifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic and hypersonic flight, or spacecraft re-entry. All of these flight regimes pose challenges for proper flight safety.

<span class="mw-page-title-main">Progress (spacecraft)</span> Russian expendable freighter spacecraft

The Progress is a Russian expendable cargo spacecraft. Its purpose is to deliver the supplies needed to sustain a human presence in orbit. While it does not carry a crew, it can be boarded by astronauts when docked to a space station, hence it is classified as crewed by its manufacturer. Progress is derived from the crewed Soyuz spacecraft and launches on the same launch vehicle, a Soyuz rocket.

<span class="mw-page-title-main">Scramjet</span> Jet engine where combustion takes place in supersonic airflow

A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion, but where as a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone. This allows the scramjet to operate efficiently at extremely high speeds.

In aerospace engineering, the propellant mass fraction is the portion of a vehicle's mass which does not reach the destination, usually used as a measure of the vehicle's performance. In other words, the propellant mass fraction is the ratio between the propellant mass and the initial mass of the vehicle. In a spacecraft, the destination is usually an orbit, while for aircraft it is their landing location. A higher mass fraction represents less weight in a design. Another related measure is the payload fraction, which is the fraction of initial weight that is payload. It can be applied to a vehicle, a stage of a vehicle or to a rocket propulsion system.

<span class="mw-page-title-main">Saturn IB</span> American rocket used in the Apollo program during the 1960s and 70s

The Saturn IB(also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage, with the S-IVB. The S-IB first stage also increased the S-I baseline's thrust from 1,500,000 pounds-force (6,700,000 N) to 1,600,000 pounds-force (7,100,000 N) and propellant load by 3.1%. This increased the Saturn I's low Earth orbit payload capability from 20,000 pounds (9,100 kg) to 46,000 pounds (21,000 kg), enough for early flight tests of a half-fueled Apollo command and service module (CSM) or a fully fueled Apollo Lunar Module (LM), before the larger Saturn V needed for lunar flight was ready.

Thrust-to-weight ratio is a dimensionless ratio of thrust to weight of a rocket, jet engine, propeller engine, or a vehicle propelled by such an engine that is an indicator of the performance of the engine or vehicle.

<span class="mw-page-title-main">Northrop HL-10</span> Type of aircraft

The Northrop HL-10 was one of five US heavyweight lifting body designs flown at NASA's Flight Research Center in Edwards, California, from July 1966 to November 1975 to study and validate the concept of safely maneuvering and landing a low lift-over-drag vehicle designed for reentry from space. It was a NASA design and was built to evaluate "inverted airfoil" lifting body and delta planform. It currently is on display at the entrance to the Armstrong Flight Research Center at Edwards Air Force Base.

<span class="mw-page-title-main">ARCAspace</span> Aerospace company headquartered in Romania

Romanian Cosmonautics and Aeronautics Association, also known as ARCAspace, is an aerospace company based in Râmnicu Vâlcea, Romania. It builds rockets, high-altitude balloons, and unmanned aerial vehicles. It was founded in 1999 as a non-governmental organization in Romania by the Romanian engineer and entrepreneur Dumitru Popescu and other rocket and aeronautics enthusiasts. Since then, ARCA has launched two stratospheric rockets and four large-scale stratospheric balloons including a cluster balloon. It was awarded two governmental contracts with the Romanian government and one contract with the European Space Agency. ARCASpace is currently developing a three-stage, semi-reusable steam-powered rocket called EcoRocket and in 2022 has shifted its business model to Asteroid mining.

<span class="mw-page-title-main">Space Shuttle orbiter</span> Reusable spacecraft component of the Space Shuttle system

The Space Shuttle orbiter is the spaceplane component of the Space Shuttle, a partially reusable orbital spacecraft system that was part of the discontinued Space Shuttle program. Operated from 1977 to 2011 by NASA, the U.S. space agency, this vehicle could carry astronauts and payloads into low Earth orbit, perform in-space operations, then re-enter the atmosphere and land as a glider, returning its crew and any on-board payload to the Earth.

<span class="mw-page-title-main">Tupolev Tu-2000</span> Russian hypersonic aircraft

The Tupolev Tu-2000 was a planned hypersonic flight experimental aircraft designed by the Tupolev design bureau. It was intended to test technologies for a single-stage-to-orbit aerospaceplane and also the Tupolev Tu-360 intercontinental bomber.

<span class="mw-page-title-main">Non-rocket spacelaunch</span> Concepts for launch into space

Non-rocket spacelaunch refers to theoretical concepts for launch into space where much of the speed and altitude needed to achieve orbit is provided by a propulsion technique that is not subject to the limits of the rocket equation. Although all space launches to date have been rockets, a number of alternatives to rockets have been proposed. In some systems, such as a combination launch system, skyhook, rocket sled launch, rockoon, or air launch, a portion of the total delta-v may be provided, either directly or indirectly, by using rocket propulsion.

<span class="mw-page-title-main">Haas (rocket)</span> Family of rocket space launchers

Haas was a family of rocket space launchers developed by ARCAspace for the Google Lunar X Prize competition and for their national crewed space program. As of 2020 no rocket has been launched, the planned rocket types changed significantly over time.

The Lockheed Star Clipper was a proposed Earth-to-orbit spaceplane based on a large lifting body spacecraft and a wrap-around drop tank. Originally proposed during a United States Air Force program in 1966, the basic Star Clipper concept lived on during the early years of the NASA Space Shuttle program, and as that project evolved, in a variety of new versions like the LS-200.

Douglas Aircraft's SASSTO, short for "Saturn Application Single Stage to Orbit", was a single-stage-to-orbit (SSTO) reusable launch system designed by Philip Bono's team in 1967. SASSTO was a study in minimalist designs, a launcher with the specific intent of repeatedly placing a Gemini capsule in orbit for the lowest possible cost. The SASSTO booster was based on the layout of the S-IVB upper stage from the Saturn family, modified with a plug nozzle. Although the SASSTO design was never followed up at Douglas, it is widely referred to in newer studies for SSTO launchers, notably the MBB "Beta" design, which was largely an updated version of SASSTO.

<span class="mw-page-title-main">Scaled Composites Stratolaunch</span> Mother ship aircraft designed to launch spacecraft

The Scaled Composites Model 351 Stratolaunch or Roc is an aircraft built by Scaled Composites for Stratolaunch Systems to carry air-launch-to-orbit (ALTO) rockets, and subsequently repurposed to offer air launch hypersonic flight testing after a change of ownership. It was announced in December 2011, rolled out in May 2017, and flew for the first time on April 13, 2019, shortly after the death of founder Paul Allen. The aircraft features a twin-fuselage design and the longest wingspan ever flown, at 385 feet (117 m), surpassing the Hughes H-4 Hercules "Spruce Goose" flying boat of 321 feet (98 m). The Stratolaunch is intended to carry a 550,000-pound (250 t) payload and has a 1,300,000-pound (590 t) maximum takeoff weight.

<span class="mw-page-title-main">Antonov An-325</span> Air-launch-to-orbit aircraft by the Soviets

The Antonov An-325 was a proposed evolution of the Antonov An-225 "Mriya", designed to launch spacecraft of various purposes into circular, elliptical and high-circle orbits, including geostationary orbit. It was planned to be an enlarged and improved version of the An-225, but was never built.

References

  1. Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 210. ISBN   9780850451634.
  2. "Payload - Define Payload at Dictionary.com". Dictionary.com. Archived from the original on 2013-12-12.
  3. Launius, Roger D. Jenkins, Dennis R. 2002. To Reach the High Frontier: A History of U.S. Launch Vehicles. Univ. Pr. of Kentucky. ISBN   978-0-8131-2245-8
  4. Jackson, Robert. de Havilland Mosquito (Combat Legend), page 15. Shrewsbury, UK: Airlife Publishing Ltd., 2003. ISBN 1-84037-358-X.
  5. "B-17 | Crew, Range, & Bomb Load | Britannica". www.britannica.com. 2024-03-06. Retrieved 2024-04-04.
  6. "Petlyakov Pe-8 (TB-7) Long-Range Strategic Heavy Bomber Aircraft Specifications and Pictures". www.militaryfactory.com. Retrieved 2024-04-04.
  7. "B-52H Stratofortress". Air Force. Retrieved 2024-04-04.
  8. "Utilisation Relevant Data" (PDF). Retrieved 2024-04-04.