Accurate airdrop


Transport C-17 GLOBEMASTER III delivers humanitarian aid on the outskirts of Port-au-Prince in Haiti January 18, 2010

This article describes the basic principles and test data delivery systems, precision air NATO, described the aircraft navigation to the release point, trajectory control, as well as the general concept of dumped goods, enabling their exact landing. In addition, the article emphasizes the need for accurate system reset, and it introduces the reader to the concepts of operations perspective.

It is worth noting the current growing interest of NATO to the exact dropping. Conference of National control of the armed NATO (NATO CNAD) established the exact dropping for special operations forces as the eighth highest priority of NATO in the fight against terrorism.

Today, most of the drop sequence performed by overflight calculated point drop from the air CARP (computed air release point), which is calculated on the basis of wind speed and ballistics system aircraft. Ballistic table (based on the average characteristics of the ballistic parachute system) determines the CARP, where cargo is discharged. These averages are often based on a dataset that includes deviations up to 100 meters of standard demolition. CARP also often calculated using the average value of the wind (with the wind at a height and surface) and the assumption of a constant profile (template), air flows from the release point to the ground. Templates are rarely constant winds from ground level to greater heights, the magnitude of the deviation depends on the influence of natural terrain and variable meteorological characteristics of wind flows, such as wind shear. Since most modern threats comes from ground fire, the current solution is to drop weight at high altitudes and the subsequent horizontal displacement, which allows the aircraft to divert from the dangerous route. Obviously, in this case, the influence of different air flows. In order to meet the requirements of aircraft dropping (hereinafter aviasbrasyvaniya) from high altitudes and prevent cargo delivered in the "wrong hands", the exact dropping from air at the conference NATO CNAD received high priority. Modern technology has made it possible to implement many innovative drop. In order to reduce the impact of all the variables that prevent accurate ballistic dropping, systems are being developed not only increase the accuracy of calculations CARP due to more accurate wind profiler, but also keeping system drop weight to a predetermined point of impact with the ground, regardless of changes in the strength and direction wind.

Influence on the achievable accuracy of air-drop

Variability - the enemy of precision. The smaller the process of change, the process is more accurate, and here aviasbrasyvanie no exception. In the process of air dropping there are many variables. Among them are uncontrollable parameters: weather, human factors, such as the difference in securing cargo and crew actions / time calculations, perforation individual parachutes, the differences in the manufacture of parachutes, the differences in the dynamics of disclosure of individual and / or group of parachutes and their influence wear. All these and many other factors influence on the achievable accuracy of any aviasbrasyvaemoy system, ballistic or managed. Some parameters can be controlled in part, such as air speed, direction and altitude. But due to the special nature of the flight, even they may vary to some extent during most drop sequence. Nevertheless, the exact dropping from air passed a long way in recent years, and rapidly developed since NATO members invest and invest heavily in technology and testing accurate drop. Currently being developed numerous quality systems precise drop, and in the near future planned development of many other technologies in this rapidly growing field of possibilities.

Navigation

The C-17, as shown in the first picture of this article has automatic features relating to the navigation of the process of accurate drop. Exact airdrop C-17 conducted using CARP, altitude point drop HARP (high-altitude release point) or algorithms of the exhaust system at low altitude parachute LAPES (low-altitude parachute extraction system). In this process, an automatic drop accounted ballistics calculations of the dumping site, signals the beginning of the drop, as well as basic data recorded at the time of discharge.

By dropping the low altitude at which the parachute system is deployed at reset load applied CARP. When activated tall Dropping HARP. Note that the difference between CARP and HARP is to calculate the trajectory of free fall when dropped from great heights.

Database aviasbrasyvaniyu aircraft C-17 contains a ballistic data of various types of goods, such as personnel, equipment or containers, as well as their respective parachutes. Computers allow you to update ballistic information and display it on the screen at any time. The database stores the parameters as input ballistic calculations performed by the onboard computer. Note that the C-17 allows you to store ballistic data not only for individual people and individual items of equipment / cargo, but also for the combination of people leaving the plane and their equipment / cargo.


JPADS SHERPA operated in Iraq from August 2004, when the center of Natick soldier deployed two systems in the Marine Corps. Previous version JPADS, eg Sherpa 1200s (pictured) has a limited carrying capacity of about 1200 pounds, while specialists riggers kits usually form a mass of about 2200 pounds


Controlled load class 2200 pounds combined system accurately aviasbrasyvaniya JPADS (Joint Precision Airdrop System) in flight during the first combat dropping. A joint team consisting of representatives of the Army, Air Force and contractor, recently revised the accuracy of this choice JPADS

Airflows

After jettison released air begin to affect the direction of movement and the fall. Onboard computer 17 calculates the C-air flow by using data from various onboard sensors flight velocity, pressure and temperature, as well as navigation sensors. Wind data can be entered manually using the information from the actual area of ​​drop (PC) or a weather forecast. Each data type has its own advantages and disadvantages. Wind sensors are very accurate, but can not show the weather conditions over the PC as the plane can not fly from the ground to a predetermined height above the PC. Surface wind is usually not the same as that at the height of the air flow, especially at high altitude. Projected wind - this prediction and do not represent the speed and direction of flow at different heights. Actual flow profiles typically not linearly dependent on the height. If the actual wind profile is not known and is not entered in the flight computer, the default errors in calculations CARP added assumption of a linear wind profile. Once these calculations are made (or the data is entered), the results are recorded in a database for use in aviasbrasyvany further calculations CARP or HARP, based on the average of actual air flow. The winds are not used for dropping technology LAPES, as cargo plane drops just above the ground at the desired point of impact. Computer on the plane C-17 calculates the deviation clean demolition in direction of the wind and perpendicular to it for aviasbrasyvany modes CARP and HARP.

System wind conditions

In rawinsonde used a GPS unit to the transmitter. He carries a probe that is available near the area before dropping dropping. The obtained data is analyzed to obtain the location of the wind profile. This profile can be used to adjust the controller drop CARP.

Research Laboratory of the Air Force control sensor systems on Wright-Patterson AFB has developed a high-energy two-micrometer transceiver Doppler LIDAR (Light Detection and Ranging - laser radar-IR) carbon dioxide with eye-safe laser 10.6 micron for measuring air currents height. It was created, first, to ensure real-time 3D maps of fields winds between the aircraft and the ground, and, secondly, to significantly improve the accuracy of the drop from high altitudes. It produces accurate measurements of typical error less than one meter per second. LIDAR following advantages: it provides full 3D wind field measurement; provides delivery of data in real time; located on the aircraft; as well as its secrecy. Disadvantages: price; useful range is limited to atmospheric disturbances; and requires little modification of the aircraft.

Due to the fact that the deviation time data and position may influence the determination of wind, especially at low altitudes, the testers must use GPS DROPSONDE device for measuring the wind in the vicinity of discharge as close as possible to the time of testing. DROPSONDE (or more fully, DROPWINDSONDE) is a compact tool (a long, thin tube), which dropped from aircraft. Air streams are set with a GPS receiver DROPSONDE, which monitors the relative Doppler frequency from the RF carrier signal satellite GPS. These Doppler frequencies are digitized and sent to the on-board information system. DROPSONDE can be deployed before the arrival of the cargo plane with another aircraft, for example, even with the jet fighter.

Parachute

Parasailing can be round parachute, glider (pancakes wing), or both at once. The system JPADS (see below), for example, is mainly used either glider or paraglider hybrid / round parachute for braking load during descent. "Managed" JPADS parachute provides direction in flight. On final descent often cargo parachutes are also used in other common system. Parachute control lines go to the device air controller AGU (airborne guidance unit) to shape the parachute / glider to manage the course. One of the main differences between the categories of braking technology, ie types of parachute is achievable horizontal offset that each type of system can provide. In the most general terms, the shift is often measured as the aerodynamic quality of L / D (lift to drag - the ratio of lift-to-drag ratio) system "for zero winds." It is clear that much more difficult to calculate the achievable displacement without precise knowledge of many parameters influencing the deviation. These parameters include air flow with which the system meets (winds can help or hinder deviations), the total available vertical distance to the drop height and the system necessary for full disclosure and planning, as well as height, which is necessary to prepare the system before the collision with the ground. In general, paragliders provide values ​​L / D in the range from 3 to 1, the hybrid system (i.e., high load on the wing gliders for controlled flight into the ground near the collision becomes ballistic provided by round domes) give L / D in the range of 2 / 2,5 - 1, whereas conventional round parachutes, controlled by sliding have L / D in the range of 0.4 / 1.0 - 1.

There are many concepts and systems have much higher ratios L / D. Many of them require a structurally rigid guiding edges or "wings" that are "laid out" during deployment. Typically, these systems are more complex and expensive for use in aviasbrasyvanii, as they seek to fill all the available volume in the cargo bay. On the other hand, more traditional parachute systems exceed the limit on the total weight of the cargo compartment.

Also for precision aviasbrasyvaniya may be considered airborne systems for cargo dropping from a great height and delayed disclosure of low altitude parachute to HALO (high-altitude low opening). These are two-stage system. The first stage, in general, is a small uncontrolled parachute system, which quickly lowers the load on most of the trajectory adjustment. The second stage - a big parachute, which opens "near" ground for the final contact with the ground. In general, these systems are much cheaper HALO precise drop control systems, and they are not that accurate, and while dropping several freight kits will cause "spread" of these goods. This spread is greater than the speed of the aircraft multiplied by the time of disclosure of all systems (often kilometer distance).