Textbook: Airborne training. Types and characteristics of parachutes Tth d6 series 3 5
The main parachute is designed for safe descent and landing of a parachutist (Fig. 8) and consists of a canopy base and lines.
The base of the dome with an area of 83 m 2 practically has the shape of a circle, consisting of four sectors and an overlay.
Each sector is made of fabric article 56011P. In the center of the base of the dome there is an overlay made of fabric article 56006P in one addition.
Rice. 8. Main parachute
1 - sling 15B; 2 - sling 15A; 3 - dome sectors; 4 - overlay; 5 - wedges of the dome panel; 6 - frame; 7 - loop-bridle; 8 - sling 1B; 9 - sling 1A; 10 - tightening tape; 11 - loop for slings; a - marking
The sectors are interconnected with a seam lock. The seams connecting the sectors of the dome are stitched with ribbons LTKP-13-70.
The lower edge of the dome is formed by bending the fabric to the outer side and reinforced with tape LTKP-15-185 stitched on it on both sides. and at the lower edge - thirty loops for attaching slings.
On the lower edge of the dome, all lines, except for lines 1A, 1B, 15A and 15B, are sewn with tightening tapes from LTKP-15-185 to reduce cases of overlapping of the dome with lines and reduce its filling time.
A bridle tape and LTKP-26-600 is sewn onto the pole part of the dome, designed to attach the link loop of the stabilizing system.
On the basis of the canopy, between the lines 1A and 1B, 15A and 15B, there are slots 1.6 m long, starting from the lower edge and designed to turn the canopy during descent.
The dome has 30 lines, 27 of which are made of ShKP-150 cord, and three lines - 1A, 1B and 28 - are made of green ShKKr-190 cord to facilitate control of the dome laying.
The slings are tied at one end to the loops of the dome, and at the other - to the half-ring buckles 1-OST 1 12002-77 of the free ends of the suspension system. The ends of the slings are stitched with a zigzag stitch.
To facilitate the laying of the main parachute on the line 14 at the lower edge of the dome and at the half-ring buckle of the suspension system, identification sleeves made of orange cotton fabric are sewn.
The length of the lines in the free state from the lower edge of the dome to the half-rings of the free ends of the suspension system is 9 m. indicating the beginning and end of the installation.
On the lower edge of the dome, to the left of the lines, their serial numbers are indicated. On the outside of the canopy, between lines 1A and 28, there is a factory marking.
Control lines are sewn onto lines 1A and 15A, 1B and 15B.
The control lines are designed to turn the parachute canopy and are made of two-fold ShKKr-190 cord of red or orange color.
The control lines (Fig. 9) are threaded through the rings sewn on the inside of the free ends of the suspension system.
Rice. 9. Main parachute in action
1 - sling 1A; 2 - sling 15A; 3 - sling 15B; 4 - sling 1B; 5 - half-ring buckle; 6 - free ends of the suspension system; 7 - control lines; 8 - rings; A - rear view
One end of the left control sling is attached to the 15A sling at a distance of 1.45 m, the second - to the 1A sling at a distance of 1.25 m from the half-ring buckles of the suspension system.
One end of the right control line is attached to line 15B at a distance of 1.45 m, the other end - to line 1B at a distance of 1.25 m from the half-ring buckles of the suspension system.
When the right control line is pulled, lines 1B and 15B are pulled, pulling the lower edge of the dome inward. The dome turns to the right. When pulling the left control line, lines 15A and 1A are pulled, pulling in the lower edge of the dome. The dome turns to the left.
The mass of the main parachute is 5.5 kg.
Landing parachute D-10- This is the system that replaced the D-6 parachute. The area of the dome is 100 square meters with improved performance and beautiful appearance - in the shape of a squash.
Designed
Designed for jumps for both novice paratroopers and paratroopers - training and combat jumps from the AN-2 aircraft, MI-8 and MI-6 helicopters and AN-12, AN-26, AN-22, IL-76 military transport aircraft with full service armament and equipment ... or without it ... Throw speed 140-400 km / h, minimum jump height 200 meters with stabilization 3 seconds, maximum - 4000 meters with a parachutist flight weight up to 140 kg. Descent speed 5 m/sec.
Horizontal speed up to 3 m/sec. The forward movement of the canopy is carried out by rolling the free ends, where the free ends are reduced by rolling, the canopy goes there... Dome turns are carried out by control lines, the canopy is unfolded due to the slots located on the dome. The length of the lines for the D-10 parachute is different ... Lighter in weight, it got more control options ...
At the end of the article I will post the full performance characteristics of the D-10 (performance characteristics)
Parachute system D-10
Parachute system D-10 many people already know that the system came to the troops ... landing showed work in the air ... convergence became much less, because there are more opportunities under an open dome to run to where there is no one ... with a parachute it will be even better in this regard .. Believe me, it's difficult ... to create a system that opens safely, give speed to the canopy, make turns, create such control that a paratrooper without jumping experience can handle it ... but for paratroopers when they go with full service weapons and equipment, maintain the rate of descent and allow easy control of the canopy ...
And in a combat situation during the landing, it is necessary to exclude as much as possible shooting-shooting at paratroopers, as at targets ...
The Research Institute of Parachute Engineering has developed a modification of the D-10 parachute... get to know...
From a height of 70 meters
The minimum drop height is 70 meters...! We have courageous paratroopers... it's scary to walk from 100 meters... :)) it's scary, because the ground is close... and from 70 meters... it's like heading into a whirlpool... :)) the ground is very close. .. I know this height, this is the approach to the last straight line on the sports dome ... but the D-10P system has been worked out for quick opening ... without stabilization for the forced opening of the knapsack ... the pull rope is attached with a carabiner to the cable in an airplane or helicopter, and the other end with a cable to close the parachute bag ... the cable is pulled out with a rope, the bag opened and the canopy went ... such an opening system for the D-1-8 parachute, series 6 ... the possibility of leaving the aircraft at a height of 70 meters is safety while landing in combat conditions ...
The maximum altitude of leaving the aircraft is 4000 meters...
The D-10P system is designed in such a way that it can be converted into the D-10 system ... and vice versa ... in other words, it can be operated without stabilization for the forced opening of the parachute or stabilization is attached, the parachute fits into work with stabilization and forward, into Sky...
The dome consists of 24 wedges, slings with a breaking strength of 150 kg each...
22 slings 4 meters long and four slings attached to the loops of the dome slots, 7 m long, made of ShKP-150 nylon cord,
22 external additional slings from the ShKP-150 cord, 3 m long
24 internal additional slings from the ShKP-120 cord, 4 m long, attached to the main slings ... two internal additional slings are attached to lines 2 and 14.
The performance characteristics of the PDS D-10
| Weight of a paratrooper with parachutes, kg | 140-150 |
| Aircraft flight speed, km/h | 140-400 |
| Maximum safe parachute opening height, m | 4000 |
| Minimum safe application height, m | 200 |
| Stabilization time, s | 3 or more |
| Speed of descent on a stabilizing parachute, m/s | 30-40 |
| The force required to open a two-cone lock using a manual opening link, kgf | no more than 16 |
| Speed of descent on the main parachute, m/s | 5 |
| Time to turn in any direction by 180 when the lock cord is removed and the free ends of the harness are pulled, s | no more than 60 |
| Time to turn in any direction by 180 with locked free ends of the suspension system, s | no more than 30 |
| Average horizontal forward and backward speed, m/s | not less than 2.6 |
| Weight of parachute system without parachute bag and parachute device AD-3U-D-165, kg, | no more than 11.7 |
| Number of applications | |
| with a total flight weight of a paratrooper-paratrooper of 140 kg, | times 80 |
| including with a total flight weight of a parachutist 150 kg | 10 |
| Shelf life without repacking, months | no more than 3 |
| Warranty period, years | 14 |
The D-10 parachute system allows the use of reserve parachutes of the Z-4, Z-5, Z-2 types. Parachute devices AD-3U-D-165, PPK-U-165A-D are used as a safety device for opening a two-cone lock.
Designed to perform jumps from transport aircraft and helicopters by paratroopers of all specialties with a full set of equipment (or without it), as well as by individual paratroopers or groups of paratroopers.
The system (with a total parachutist flight weight of 140 kg) provides:
reliable operation at an altitude of 200-8000 m with stabilization for 3 s when leaving the aircraft at a speed of 38.9-111.1 m/s (140-400 km/h) when the main parachute is activated at an altitude of not more than 5000 m, if the total flight weight of the skydiver is 140 kg, and at an altitude of not more than 2000 m, if the total flight weight of the skydiver is 150 kg,
the minimum safe altitude when leaving a horizontally flying aircraft at a flight speed of 38.9-111.1 m/s (140-400 km/h) according to the instrument:
with stabilization 3 s - 200 m,
with stabilization 2 s - 150 m,
neutral position of the canopy of the main parachute during descent, as well as a turn in any direction by 180 ° in 15-25 s in the presence of a cord for blocking the free ends of the harness:
turn in any direction by 180° in 29-60 s when the locking cord is removed and the free ends of the harness are tightened;
sustained descent on both main and stabilizing parachutes:
termination of the descent on the stabilizing parachute and the introduction of the main parachute by opening the two-cone lock both by the paratrooper himself using the manual opening link, and by the PPK-U-165AD (AD-ZU-D-165) device:
reliability of operation of reserve parachutes of types 3-5 and 3-2 in case of non-departure of the stabilizing parachute or failure of the landing parachute system, as well as at a rate of descent of more than 8.5 m/s in the event of the canopy of the main parachute being overwhelmed by lines;
adjustment of the suspension system on paratroopers with a height of 1.5-1.9 m, in winter and summer landing equipment:
extinguishing the canopy of the main parachute at the time of landing (splashing down) at high wind speeds near the ground using a device for disconnecting the right free end of the harness;
exclusion of detachment of parts of the parachute system during the entire landing process:
fastening of a cargo container GK-30 (GK-ZOU);
convenient placement of the parachutist in the aircraft on standard landing equipment.
The canopy of the main parachute is 83m2 and has the shape of a circle with two slots at the lower edge.
1. stabilizing parachute chamber
2. stabilizing parachute
3. main parachute chamber
4. main parachute
5. satchel
The D-6 series 4 landing parachute system operates according to a cascade scheme. The stabilizing parachute goes into action first. The decrease on it occurs until the time specified on the PPK-U-165A-D (AD-ZU-D-165) device. After the device is triggered, the stabilizing parachute removes the chamber with the main parachute from the satchel. The design of the D-6 series 4 parachute system provides for two ways to deploy the main parachute canopy with a normally operating stabilizing parachute: using the PPK-U-165A-D (AD-ZU-D-165) device or the manual deployment link. When the parachutist separates from the aircraft (helicopter), a stabilizing parachute is pulled out of the chamber and put into action.
At the moment of filling the canopy of the stabilizing parachute, the link is pulled and pulls out the flexible pin from the device PPK-U-165A-D (AD-ZU-D-165), which is connected to the link using a 0.36 m long halyard.
After filling the canopy of the stabilizing parachute, a stabilized descent of the parachutist occurs. In this case, the satchel of the main parachute remains closed. The termination of the stabilized descent, the release of the knapsack valves and the introduction of the main parachute is carried out after the opening of the two-cone lock manually (using the manual opening link) or the PPK-U-165A-D (AD-ZU-D-165) device, as a result of which the stabilizing the parachute pulls the chamber out of the satchel with the main parachute stowed in it. As the parachutist descends, the main parachute chamber moves away from him and the lines of the main parachute come out of its cells evenly.
When the lines are fully tensioned, the removable rubber cells of the chamber are released and the lower free part of the main parachute canopy 0.2 m long, not clamped by an elastic ring, begins to emerge from it. As the stabilizing parachute with the main parachute chamber moves away from the parachutist, the rest of the canopy evenly leaves the chamber until the entire system is fully tensioned.
The filling of the canopy of the main parachute begins after it leaves the chamber by about half and ends after the chamber is completely pulled from it.
Landing troops are required to undergo jump training at the training stage. Then the skydiving skills are already used during military operations or demonstration performances. Jumping has special rules: requirements for parachutes, aircraft used, training of soldiers. All these requirements must be known to the landing party for a safe flight and landing.
A paratrooper cannot jump without preparation. Training is an obligatory stage before the start of real airborne jumps, during which theoretical training and jumping practice take place. All the information that is told to future paratroopers during training is given below.
Aircraft for transportation and landing
What aircraft do paratroopers jump from? The Russian army currently uses several aircraft for landing troops. The main one is IL-76, but other flying machines are also used:
- AN-12;
- MI-6;
- MI-8.
The IL-76 remains the preferred choice because it is the most conveniently equipped for landing, has a large luggage compartment and retains pressure well even at high altitudes, if the landing party needs to jump there. Its body is sealed, but in case of emergency, the compartment for paratroopers is equipped with individual oxygen masks. Thus, each skydiver will not experience a lack of oxygen during the flight.
The aircraft develops speeds of approximately 300 km per hour, and this is the optimal indicator for landing in military conditions.
Jump Height
From what height do paratroopers usually jump with a parachute? The altitude of the jump depends on the type of parachute and the aircraft used for landing. The recommended optimal landing height is 800-1000 meters above the ground. This indicator is convenient in combat conditions, since at such an altitude the aircraft is less exposed to fire. At the same time, the air is not too rarefied for the paratrooper to land.
From what height do paratroopers usually jump in case of non-training actions? The opening of the D-5 or D-6 parachute during landing from the IL-76 occurs at an altitude of 600 meters. The usual distance required for full disclosure is 200 meters. That is, if the landing starts from a height of 1200, then the opening will occur at around 1000. The maximum allowable for landing is 2000 meters.
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More advanced models of parachutes allow you to start landing from a mark of several thousand meters. So, the modern model D-10 allows you to land at a maximum height of no more than 4000 m above the ground. At the same time, the minimum allowable level for deployment is 200. It is recommended to start deployment earlier to reduce the likelihood of injury and a hard landing.
Types of parachutes
Since the 1990s, two main types of landing parachutes have been used in Russia: D-5 and D-6. The first is the simplest, does not allow you to adjust the landing site. How many lines does a paratrooper's parachute have? Depends on the model. Lines in D-5 28, the ends are fixed, which is why it is impossible to adjust the direction of flight. The length of the lines is 9 meters. The weight of one set is about 15 kg.
A more advanced D-5 model is the D-6 paratrooper parachute. In it, the ends of the lines can be released and the threads can be pulled, adjusting the direction of flight. To turn left, you need to pull the lines on the left, to maneuver to the right side, pull the thread on the right. The area of the parachute dome is the same as that of the D-5 (83 square meters). The weight of the kit is reduced - only 11 kilograms, it is most convenient for still being trained, but already trained paratroopers. During the training, about 5 jumps are made (with express courses), D-6 is recommended to be issued after the first or second. There are 30 rafters in the kit, four of them allow you to control the parachute.
For complete beginners, D-10 kits have been developed, this is an updated version, which has only recently been made available to the army. There are more rafters here: 26 main and 24 additional. Of the 26 feet, 4 allow you to control the system, their length is 7 meters, and the remaining 22 - 4 meters. It turns out that there are only 22 external additional lines and 24 internal additional lines. Such a number of cords (all of them are made of nylon) allow you to control the flight as much as possible, adjust the course during disembarkation. The area of the dome at the D-10 is as much as 100 square meters. At the same time, the dome is made in the shape of a squash, a comfortable green color without a pattern, so that after landing a paratrooper it would be harder to detect it.
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Rules for disembarking from an aircraft
The paratroopers disembark from the cabin in a certain order. In IL-76 this happens in several streams. For disembarkation, there are two side doors and a ramp. During training activities, they prefer to use exclusively side doors. Disembarkation can be carried out:
- in one stream of two doors (with a minimum of personnel);
- in two streams from two doors (with an average number of paratroopers);
- in three or four streams from two doors (with large-scale educational activities);
- in two streams and from the ramp, and from the doors (during hostilities).
The distribution into streams is done so that the jumpers do not collide with each other upon landing and cannot be hooked. A small delay is made between threads, usually several tens of seconds.
Parachute flight and deployment mechanism
After landing, the paratrooper must calculate 5 seconds. It cannot be considered a standard method: "1, 2, 3 ...". It will turn out too quickly, the real 5 seconds will not pass yet. It is better to count like this: "121, 122 ...". Now the most commonly used account is starting from 500: "501, 502, 503 ...".
Immediately after the jump, the stabilizing parachute automatically opens (the stages of its opening can be seen on the video). This is a small dome that prevents the paratrooper from starting to "circle" during the fall. Stabilization prevents flips in the air, in which a person begins to fly upside down (this position does not allow the parachute to open).
After five seconds, the stabilization is completely removed, and the main dome must be activated. This is done either with the help of a ring, or automatically. A good paratrooper should be able to adjust the opening of the parachute himself, so trained students are given kits with a ring. After activating the ring, the main dome fully opens in 200 meters of fall. The duties of a trained paratrooper paratrooper also include camouflage after landing.
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Safety rules: how to protect the landing from injury
Parachutes require special treatment, care, so that jumps using them are as safe as possible. Immediately after use, the parachute must be properly folded, otherwise its service life will be drastically reduced. An improperly folded parachute may fail to deploy during landing, resulting in death.
1. HISTORY OF THE DEVELOPMENT OF THE PARACHUTE AND MEANS OF LANDING WEAPONS, MILITARY EQUIPMENT AND CARGO
The origin and development of airborne training is connected with the history of parachuting and the improvement of the parachute.
The creation of various devices for safe descent from a great height goes back centuries. A scientifically based proposal of this kind is the invention of Leonardo da Vinci (1452 - 1519). He wrote: "If a person has a tent of starched linen 12 cubits wide and 12 high, then he can throw himself from any height without danger to himself." The first practical jump was made in 1617, when the Venetian mechanical engineer F. Veranzio made a device and, jumping from the roof of a high tower, landed safely.
The word "parachute", which has survived to this day, was proposed by the French scientist S. Lenormand (from the Greekpara– against and Frenchchute- the fall). He built and personally tested his apparatus, having made a jump from the window of the observatory in 1783.
The further development of the parachute is associated with the appearance of balloons, when it became necessary to create life-saving devices. Parachutes used on balloons had either a hoop or spokes so that the canopy was always in the open state, and it could be used at any time. Parachutes in this form were attached under the gondola of the balloon or were an intermediate connecting link between the balloon and the gondola.
In the 19th century, a pole hole began to be made in the parachute dome, hoops and knitting needles were removed from the dome frame, and the parachute dome itself began to be attached to the side of the balloon shell.
The pioneers of domestic parachuting are Stanislav, Jozef and Olga Drevnitsky. Jozef by 1910 had already made more than 400 parachute jumps.
In 1911, G. E. Kotelnikov developed and patented the RK-1 backpack parachute. It was successfully tested on June 19, 1912. The new parachute was compact and met all the basic requirements for use in aviation. Its dome was made of silk, the slings were divided into groups, the suspension system consisted of a belt, chest girth, two shoulder straps and leg girths. The main feature of the parachute was its autonomy, which makes it possible to use it regardless of the aircraft.
Until the end of the 1920s, parachutes were created and improved in order to save the life of an aeronaut or pilot in the event of a forced flight from an aircraft in the air. The escape technique was worked out on the ground and was based on theoretical and practical studies of a parachute jump, knowledge of the recommendations for leaving the aircraft and the rules for using a parachute, i.e., the foundations of ground training were laid.
Without training in the practical performance of the jump, parachute training was reduced to teaching the pilot to put on a parachute, separate from the aircraft, pull out the exhaust ring, and after opening the parachute it was recommended: “when approaching the ground, preparing for the descent, take a sitting position in the help, but so so that the knees are lower than the hips. Do not try to get up, do not strain your muscles, lower yourself freely, and if necessary, then roll on the ground.
In 1928, the commander of the troops of the Leningrad Military District, M. N. Tukhachevsky, was entrusted with the development of a new Field Manual. The work on the draft regulations necessitated the operational department of the headquarters of the military district to prepare an abstract for discussion on the topic "Airborne assault operations in an offensive operation."
In theoretical works, it was concluded that the very technique of landing airborne assault forces and the nature of their combat behind enemy lines place increased demands on the personnel of the landing force. Their training program should be built on the basis of the requirements of airborne operations, covering a wide area of skills and knowledge, since every fighter is registered in the airborne assault. It was emphasized that the excellent tactical training of each member of the landing force must be combined with his exceptional decisiveness, based on a deep and quick assessment of the situation.
In January 1930, the Revolutionary Military Council of the USSR approved a reasonable program for the construction of certain types of aircraft (airplanes, balloons, airships), which were to fully take into account the needs of a new, emerging branch of the military - air infantry.
On July 26, 1930, the first parachute exercises in the country with jumping from an airplane were opened to test the theoretical provisions in the field of the use of airborne assaults at the airfield of the 11th air brigade in Voronezh on July 26, 1930. 30 paratroopers were trained for the purpose of dropping an experimental airborne assault at the upcoming experimental demonstration exercise of the Air Force of the Moscow Military District. In the course of solving the tasks of the exercise, the main elements of airborne training were reflected.
10 people were selected to participate in the landing. The landing force was divided into two groups. The first group and the detachment as a whole was led by a military pilot, a participant in the Civil War, an enthusiast of the parachute business brigade commander L. G. Minov, the second - by a military pilot Ya. D. Moshkovsky. The main purpose of this experiment was to demonstrate to the participants in the aviation exercise the technique of dropping parachute troops and delivering them the weapons and ammunition necessary for combat. The plan also provided for the study of a number of special issues of parachute landing: the reduction of paratroopers in conditions of simultaneous group drop, the rate of paratrooper drop, the magnitude of their dispersion and the time of collection after landing, the time spent on finding weapons dropped by parachute, and the degree of its safety.
Preliminary training of personnel and weapons before landing was carried out on combat parachutes, and training was carried out directly on the aircraft from which the jump was to be made.
On August 2, 1930, an airplane took off from the airfield with the first group of paratroopers led by L. G. Minov and three R-1 aircraft, which carried two containers with machine guns, rifles, and ammunition under their wings. Following the first, a second group of paratroopers headed by Ya. D. Moshkovsky was thrown out. The paratroopers, quickly collecting parachutes, headed to the assembly point, unpacked the containers along the way and, having dismantled the weapons, began to carry out the task.
August 2, 1930 went down in history as the birthday of the airborne troops. Since that time, the parachute has a new purpose - to ensure the landing of troops behind enemy lines, and a new type of troops has appeared in the Armed Forces of the country.
In 1930, the country's first factory for the production of parachutes was opened, its director, chief engineer and designer was M.A. Savitsky. In April of the same year, the first prototypes of the NII-1 type rescue parachute, PL-1 rescue parachutes for pilots, PN-1 for pilot-observers (navigators) and PT-1 parachutes for training jumps by flight personnel were manufactured. Air Force, paratroopers and paratroopers.
In 1931, at this factory, PD-1 parachutes designed by M.A. Savitsky were manufactured, which, starting from 1933, began to be supplied to parachute units.
Created by that time, airborne soft bags (PAMM), paratrooper gasoline tanks (PDBB) and other types of landing containers mainly provided for the parachute drop of all types of light weapons and combat cargo.
Simultaneously with the creation of the production base for parachute construction, research work was widely developed, which set itself the following tasks:
Creation of such a design of a parachute that would withstand the load received after opening when jumping from an aircraft flying at maximum speed;
Creation of a parachute that provides minimal overload on the human body;
Determination of the maximum allowable overload for the human body;
The search for such a shape of the dome, which, at the lowest cost of material and ease of manufacture, would provide the lowest rate of descent of the parachutist and would prevent him from swinging.
At the same time, all theoretical calculations had to be verified in practice. It was necessary to determine how safe a parachute jump is from one or another point of the aircraft at maximum flight speed, to recommend safe methods of separation from the aircraft, to study the trajectory of the parachutist after separation at various flight speeds, to study the effect of a parachute jump on the human body. It was very important to know whether every paratrooper would be able to open the parachute manually or if a special medical selection was necessary.
As a result of research by doctors of the Military Medical Academy, materials were obtained that for the first time highlighted the issues of the psychophysiology of parachute jumping and were of practical importance for the selection of candidates for the training of instructors in parachute training.
To solve the tasks of landing, bombers TB-1, TB-3 and R-5, as well as some types of aircraft of the civil air fleet (ANT-9, ANT-14 and later PS-84) were used. The PS-84 aircraft could transport parachute suspensions, and when loaded internally, it could take 18-20 PDMMs (PDBB-100), which could be thrown out simultaneously through both doors by paratroopers or crew.
In 1931, the combat training plan of an airborne assault detachment contained parachute training for the first time. To master the new discipline in the Leningrad Military District, training camps were organized, at which seven parachute instructors were trained. Parachute training instructors carried out a lot of experimental work in order to gain practical experience, so they jumped on the water, on the forest, on the ice, with additional cargo, with winds up to 18 m / s, with various weapons, with shooting and throwing grenades in the air.
The beginning of a new stage in the development of airborne troops was laid by a resolution of the Revolutionary Military Council of the USSR, adopted on December 11, 1932, in which it was planned to form one airborne detachment in the Belarusian, Ukrainian, Moscow and Volga military districts by March 1933.
In Moscow, on May 31, 1933, the Higher Parachute School OSOAVIAKHIM was opened, which began the systematic training of paratrooper instructors and parachute handlers.
In 1933, jumps in winter conditions were mastered, the temperature possible for mass jumps, the wind strength near the ground, the best way to land, and the need to develop special paratrooper uniforms convenient for jumping and for actions on the ground during the battle.
In 1933, the PD-2 parachute appeared, three years later the PD-6 parachute, the dome of which had a round shape and an area of 60.3 m 2 . Mastering new parachutes, techniques and methods of landing, and having accumulated sufficient practice in performing various parachute jumps, paratrooper instructors gave recommendations on improving ground training, on improving the methods of leaving the aircraft.
The high professional level of paratrooper instructors allowed them to prepare 1,200 paratroopers for landing in the fall of 1935 at the exercises of the Kyiv district, more than 1,800 people near Minsk in the same year, and 2,200 paratroopers at the exercises of the Moscow military district in 1936.
Thus, the experience of the exercises and the successes of Soviet industry allowed the Soviet command to determine the role of airborne operations in modern combat and move from experiments to the organization of parachute units. The Field Manual of 1936 (PU-36, § 7) stated: “Airborne units are an effective means for disorganizing the control and work of the enemy’s rear. In cooperation with troops advancing from the front, paratrooper units can exert a decisive influence on the complete defeat of the enemy in a given direction.
In 1937, in order to prepare civilian youth for military service, the Course of Educational and Sports Parachute Training (KUPP) of the USSR OSOAVIAKhIM for 1937 was introduced, in which task No. 17 included such an element as a jump with a rifle and folding skis.
The teaching aids for airborne training were instructions for packing parachutes, which were also parachute documents. Later, in 1938, the Technical Description and Instructions for Packing Parachutes were published.
In the summer of 1939, a gathering of the best paratroopers of the Red Army was held, which was a demonstration of the enormous successes achieved by our country in the field of parachuting. In terms of its results, the nature and mass nature of the jumps, the collection was an outstanding event in the history of parachuting.
The experiences of the jumps were analyzed, discussed, generalized, and all the best, acceptable for mass training, was brought to the parachute training instructors at the training camp.
In 1939, a safety device appeared as part of the parachute. The Doronin brothers - Nikolai, Vladimir and Anatoly created a semi-automatic device (PPD-1) with a clock mechanism that opens the parachute after a specified time after the paratrooper has separated from the aircraft. In 1940, the PAS-1 parachute device was developed with an aneroid device designed by L. Savichev. The device was designed to automatically open the parachute at any given height. Subsequently, the Doronin brothers, together with L. Savichev, designed a parachute device, connecting a temporary device with an aneroid device and calling it KAP-3 (combined automatic parachute). The device ensured the opening of the parachute at a given height or after a specified time after the separation of the paratrooper from the aircraft in any conditions, if for some reason the paratrooper himself did not do this.
In 1940, the PD-10 parachute was created with a dome area of 72 m 2 , in 1941 - the PD-41 parachute, the percale dome of this parachute with an area of 69.5 m 2 had a square shape. In April 1941, the Air Force Research Institute completed field tests of suspensions and platforms for dropping 45-mm anti-tank guns, motorcycles with sidecars, etc. by parachute.
The level of development of airborne training and paratroopers ensured the fulfillment of command tasks during the Great Patriotic War.
The first small airborne assault in the Great Patriotic War was used near Odessa. It was thrown out on the night of September 22, 1941 from a TB-3 aircraft and had the task of disrupting enemy communications and control with a series of sabotage and fire, creating panic behind enemy lines and thereby pulling part of its forces and means from the coast. Having landed safely, the paratroopers, alone and in small groups, successfully completed the task.
Airborne landing in November 1941 in the Kerch-Feodosia operation, landing of the 4th airborne corps in January - February 1942 in order to complete the encirclement of the Vyazemsky enemy grouping, landing of the 3rd and 5th Guards airborne brigades in the Dnieper airborne operation in September 1943 made an invaluable contribution to the development of airborne training. For example, on October 24, 1942, an airborne assault was landed directly on the Maykop airfield to destroy aircraft at the airfield. The landing was carefully prepared, the detachment was divided into groups. Each paratrooper made five jumps day and night, all actions were carefully played.
For the personnel, a set of weapons and equipment was determined depending on the task they performed. Each paratrooper of the sabotage group had a machine gun, two disks with cartridges and an additional three incendiary devices, a flashlight and food for two days. The cover group had two machine guns, the paratroopers of this group did not take some weapons, but had an additional 50 machine gun rounds.
As a result of the detachment's attack on the Maikop airfield, 22 enemy aircraft were destroyed.
The situation that developed during the war required the use of airborne troops both for operations as part of airborne assaults behind enemy lines and for operations from the front as part of guards rifle formations, which placed additional requirements on airborne training.
After each landing, the experience was summarized, and the necessary amendments were made in the training of paratroopers. So, in the manual for the commander of the airborne units, published in 1942, in chapter 3 it was written: “Training in the installation and operation of the material part of the PD-6, PD-6PR and PD-41-1 landing parachutes should be carried out according to the technical descriptions of these parachutes set out in special brochures, ”and in the section“ Fitting weapons and equipment for a combat jump ”it was indicated:“ For training, order to prepare parachutes, rifles, submachine guns, light machine guns, grenades, portable shovels or axes, cartridge pouches, bags for light machine gun magazines, raincoats, knapsacks or duffel bags. In the same figure, a sample of the attachment of a weapon was shown, where the muzzle of the weapon was attached to the main girth with the help of an elastic band or a trencher.
The difficulty of putting a parachute into action using an exhaust ring, as well as the accelerated training of paratroopers during the war, necessitated the creation of a parachute that opens automatically. For this purpose, in 1942, a parachute PD-6-42 was created with a round dome shape with an area of 60.3 m 2 . For the first time on this parachute, a pull rope was used, which ensured the opening of the parachute by force.
With the development of the airborne troops, the system of training command personnel is developing and improving, which was initiated by the creation in August 1941 in the city of Kuibyshev of the airborne school, which in the fall of 1942 was relocated to Moscow. In June 1943, the school was disbanded, and training continued at the Higher Officer Courses of the Airborne Forces. In 1946, in the city of Frunze, to replenish the officer cadres of the airborne troops, a military parachute school was formed, the students of which were officers of the Airborne Forces and graduates of infantry schools. In 1947, after the first graduation of retrained officers, the school was relocated to the city of Alma-Ata, and in 1959 to the city of Ryazan.
The school program included the study of airborne training (ADP) as one of the main disciplines. The methodology for passing the course was built taking into account the requirements for airborne assault forces in the Great Patriotic War.
After the war, the airborne training course was constantly taught with a generalization of the experience of ongoing exercises, as well as recommendations from research and design organizations. The classrooms, laboratories and parachute camps of the school are equipped with the necessary parachute shells and simulators, models of military transport aircraft and helicopters, slipways (parachute swings), springboards, etc., which ensures that the educational process is conducted in accordance with the requirements of military pedagogy.
All parachutes produced before 1946 were designed for jumping from aircraft at a flight speed of 160–200 km/h. In connection with the emergence of new aircraft and an increase in the speed of their flight, it became necessary to develop parachutes that ensure normal jumping at speeds up to 300 km / h.
An increase in the speed and altitude of aircraft flight required a fundamental improvement in the parachute, the development of the theory of parachute jumps and the practical development of jumps from high altitudes using oxygen parachute devices, at different speeds and flight modes.
In 1947, the PD-47 parachute was developed and produced. The authors of the design N. A. Lobanov, M. A. Alekseev, A. I. Zigaev. The parachute had a square percale dome with an area of 71.18 m 2 and a mass of 16 kg.
Unlike all previous parachutes, the PD-47 had a cover that was put on the main canopy before being placed in a satchel. The presence of the cover reduced the likelihood of the canopy being overwhelmed by lines, ensured the sequence of the opening process and reduced the dynamic load on the parachutist at the time of filling the canopy with air. So the problem of landing at high speeds was solved. At the same time, along with the solution of the main task - ensuring landing at high speeds, the PD-47 parachute had a number of disadvantages, in particular, a large dispersion area for paratroopers, which created a threat of their convergence in the air during a mass landing. In order to eliminate the shortcomings of the PD-47 parachute, a group of engineers led by F.D. Tkachev in 1950 - 1953. developed several variants of landing parachutes of the Pobeda type.
In 1955, the D-1 parachute with an area of 82.5 m was adopted to supply the airborne troops. 2 round shape, made of percale, weighing 16.5 kg. The parachute made it possible to jump from aircraft at flight speeds up to 350 km/h.
In 1959, in connection with the advent of high-speed military transport aircraft, it became necessary to improve the D-1 parachute. The parachute was equipped with a stabilizing parachute, and the parachute pack, main canopy cover and exhaust ring were also upgraded. The authors of the improvement were the brothers Nikolai, Vladimir and Anatoly Doronin. The parachute was named D-1-8.
In the seventies, a more advanced landing parachute D-5 entered service. It is simple in design, easy to operate, has a single laying method and allows jumping from all types of military transport aircraft into several streams at speeds up to 400 km/h. Its main differences from the D-1-8 parachute are the absence of an exhaust ball parachute, the immediate activation of the stabilizing parachute, and the absence of covers for the main and stabilizing parachutes. The main dome with an area of 83 m 2 has a round shape, made of nylon, weight of the parachute is 13.8 kg. A more advanced type of D-5 parachute is the D-6 parachute and its modifications. It allows you to freely turn in the air with the help of special control lines, as well as significantly reduce the speed of the parachutist's drift downwind by moving the free ends of the harness.
At the end of the twentieth century, the airborne troops received an even more advanced parachute system - the D-10, which, thanks to the increased area of \u200b\u200bthe main dome (100 m 2 ) allows you to increase the flight weight of the paratrooper and provides a lower speed of its descent and landing. Modern parachutes, characterized by high deployment reliability and making it possible to perform jumps from any height and at any flight speed of military transport aircraft, are constantly being improved, so the study of parachute jumping technique, the development of ground training methods and practical jumping continues.
2. THEORETICAL FOUNDATIONS OF PARACHUTE JUMP
Any body falling in the Earth's atmosphere experiences air resistance. This property of the air is based on the principle of operation of the parachute. The introduction of the parachute into action is carried out either immediately after the separation of the parachutist from the aircraft, or after some time. Depending on the time after which the parachute is put into action, its opening will occur under different conditions.
Information about the composition and structure of the atmosphere, meteorological elements and phenomena that determine the conditions for skydiving, practical recommendations for calculating the main parameters of the movement of bodies in the air and during landing, general information about landing parachute systems, purpose and composition, the operation of a parachute canopy allow the most competent use of the material part of the parachute systems, to master ground training more deeply and increase the safety of jumping.
2.1. COMPOSITION AND STRUCTURE OF THE ATMOSPHERE
The atmosphere is the environment in which flights of various aircraft are carried out, parachute jumps are made, and airborne equipment is used.
Atmosfera - the air shell of the Earth (from the Greek atmos - steam and sphairf - ball). Its vertical extent is more than three terrestrial
radii (the conditional radius of the Earth is 6357 km).
About 99% of the total mass of the atmosphere is concentrated in the layer near the earth's surface up to a height of 30-50 km. The atmosphere is a mixture of gases, water vapor and aerosols, i.e. solid and liquid impurities (dust, products of condensation and crystallization of combustion products, particles of sea salt, etc.).
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Rice. 1. The structure of the atmosphere |
The volume of the main gases is: nitrogen 78.09%, oxygen 20.95%, argon 0.93%, carbon dioxide 0.03%, the share of other gases (neon, helium, krypton, hydrogen, xenon, ozone) is less than 0 01%, water vapor - in variable quantities from 0 to 4%.
The atmosphere is vertically divided into layers, which differ in the composition of the air, the nature of the interaction of the atmosphere with the earth's surface, the distribution of air temperature with height, the influence of the atmosphere on the flights of aircraft (Fig. 1.1).
According to the composition of the air, the atmosphere is divided into the homosphere - a layer from the earth's surface to a height of 90 - 100 km and the heterosphere - a layer above 90 -100 km.
According to the nature of the influence on the use of aircraft and airborne vehicles, the atmosphere and near-Earth outer space, where the influence of the Earth's gravitational field on the flight of an aircraft is decisive, can be divided into four layers:
Airspace (dense layers) - from 0 to 65 km;
Surface outer space - from 65 to 150 km;
Near space - from 150 to 1000 km;
Deep space - from 1000 to 930,000 km.
According to the nature of the air temperature distribution along the vertical, the atmosphere is divided into the following main and transitional (given in brackets) layers:
Troposphere - from 0 to 11 km;
(tropopause)
Stratosphere - from 11 to 40 km;
(stratopause)
Mesosphere - from 40 to 80 km;
(mesopause)
Thermosphere - from 80 to 800 km;
(thermopause)
Exosphere - above 800 km.
2.2. BASIC ELEMENTS AND PHENOMENA OF WEATHER, AFFECTING PARACHUTE JUMP
weathercalled the physical state of the atmosphere at a given time and place, characterized by a combination of meteorological elements and atmospheric phenomena. The main meteorological elements are temperature, atmospheric pressure, air humidity and density, wind direction and speed, cloudiness, precipitation and visibility.
Air temperature. Air temperature is one of the main meteorological elements that determine the state of the atmosphere. The air density, which affects the speed of the skydiver's descent, and the degree of saturation of the air with moisture, which determines the operational limitations of parachutes, mainly depend on temperature. Knowing the air temperature, they determine the form of clothing for the paratroopers and the possibility of jumping (for example, in winter conditions, parachuting is allowed at temperatures not lower than 35 0 C).
The change in air temperature occurs through the underlying surface - water and land. The earth's surface, heating up, becomes warmer than the air during the day, and heat begins to be transferred from the soil to the air. Air near the ground and in contact with it heats up and rises, expands and cools. At the same time, colder air descends, which compresses and heats up. The upward movement of air is called ascending currents, and the downward movement is called descending currents. Usually the speed of these streams is small and equal to 1 - 2 m/s. Vertical streams reach their greatest development in the middle of the day - about 12 - 15 hours, when their speed reaches 4 m / s. At night, the soil cools due to heat radiation and becomes colder than the air, which also begins to cool, giving off heat to the soil and the upper, colder layers of the atmosphere.
Atmosphere pressure. The value of atmospheric pressure and temperature determine the value of air density, which directly affects the nature of the opening of the parachute and the rate of descent of the parachute.
Atmosphere pressure - pressure created by a mass of air from a given level to the top of the atmosphere and measured in pascals (Pa), millimeters of mercury (mm Hg) and bar (bar). Atmospheric pressure varies in space and time. The pressure decreases with height due to the decrease in the overlying air column. At an altitude of 5 km, it is approximately two times less than at sea level.
Air density. Air density is the meteorological element of the weather, on which the nature of the opening of the parachute and the rate of descent of the parachutist depend. It increases with decreasing temperature and increasing pressure, and vice versa. Air density directly affects the vital activity of the human body.
Density - the ratio of the mass of air to the volume that it occupies, expressed in g / m 3 depending on its composition and water vapor concentration.
Air humidity. The content of the main gases in the air is quite constant, at least up to an altitude of 90 km, while the content of water vapor varies within wide limits. Humidity of more than 80% adversely affects the strength of the parachute fabric, so taking into account humidity is of particular importance during its storage. In addition, when operating a parachute, it is forbidden to lay it in an open area in rain, snowfall or on wet ground.
Specific humidity is the ratio of the mass of water vapor to the mass of moist air in the same volume, expressed respectively in grams per kilogram.
The influence of air humidity directly on the rate of descent of a parachutist is insignificant and is usually not taken into account in calculations. However, water vapor plays an extremely important role in determining the meteorological conditions for jumping.
Wind represents the horizontal movement of air relative to the earth's surface. The immediate cause of the occurrence of wind-ra is the uneven distribution of pressure. When a difference in atmospheric pressure appears, air particles begin to move with acceleration from an area of higher to an area of lower pressure.
Wind is characterized by direction and speed. The direction of the wind, accepted in meteorology, is determined by the point on the horizon from which the air moves, and is expressed in whole degrees of a circle, counted from the north in a clockwise direction. Wind speed is the distance traveled by air particles per unit time. In terms of speed, the wind is characterized as follows: up to 3 m / s - weak; 4 - 7 m/s - moderate; 8 - 14 m / s - strong; 15 - 19 m / s - very strong; 20 - 24 m/s - storm; 25 - 30 m/s - severe storm; more than 30 m/s - hurricane. There are even and gusty winds, in direction - constant and changing. The wind is considered gusty if its speed changes by 4 m/s within 2 minutes. When the direction of the wind changes by more than one rhumb (in meteorology, one rhumb is equal to 22 0 30 / ), it is called changing. A short-term sharp increase in wind up to 20 m/s or more with a significant change in direction is called a squall.
2.3. PRACTICAL RECOMMENDATIONS FOR CALCULATION
MAIN PARAMETERS OF THE MOVEMENT OF BODIES IN THE AIR
AND THEIR LANDINGS
Critical speed of falling body. It is known that when a body falls in an air medium, it is affected by the force of gravity, which in all cases is directed vertically downward, and the force of air resistance, which is directed at each moment in the direction opposite to the direction of the fall velocity, which in turn varies both in magnitude and and in direction.
Air resistance acting in the direction opposite to the movement of the body is called drag. According to experimental data, the drag force depends on the density of air, the speed of the body, its shape and size.
The resultant force acting on the body imparts its accelerationa, calculated by formula a = G – Q , (1)
t
where G- gravity; Q- force of frontal air resistance;
m- body mass.
From equality (1) follows that
if G – Q > 0, then the acceleration is positive and the speed of the body increases;
if G – Q < 0, then the acceleration is negative and the speed of the body decreases;
if G – Q = 0 , then the acceleration is zero and the body falls at a constant speed (Fig. 2).
P a r a chute drop speed is set. The forces that determine the parachutist's trajectory are determined by the same parameters as when any body falls in the air.
The drag coefficients for various positions of the skydiver's body during a fall relative to the oncoming air flow are calculated knowing the transverse dimensions, air density, air flow velocity and by measuring the drag value. For the production of calculations, such a value as middel is necessary.
Midsection (midsection) - the largest cross-section of an elongated body with smooth curvilinear contours. To determine the midsection of a skydiver, you need to know his height and the width of his outstretched arms (or legs). In the practice of calculations, the width of the arms is taken equal to the height, so the midsection of the parachutist is equal tol 2 . The midsection changes when the position of the body in space changes. For convenience of calculations, the midsection value is assumed to be constant, and its actual change is taken into account by the corresponding drag coefficient. The drag coefficients for various positions of the bodies relative to the oncoming air flow are given in the table.
Table 1
Drag coefficient of various bodies
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The steady rate of falling of the body is determined by the mass density of air, which varies with height, the force of gravity, which varies in proportion to the mass of the body, the midsection and the drag coefficient of the parachutist.
Decrease of the cargo-parachute system. Dropping a load with a parachute canopy filled with air is a special case of an arbitrary body falling in the air.
As for an isolated body, the landing speed of the system depends on the lateral load. Changing the area of the parachute canopyFn, we change the lateral load, and therefore the landing speed. Therefore, the required landing speed of the system is provided by the area of the parachute canopy, calculated from the conditions of the operational limitations of the system.
Parachutist descent and landing. The steady speed of the parachutist's fall, equal to the critical filling speed of the canopy, is extinguished when the parachute opens. A sharp decrease in the rate of fall is perceived as a dynamic impact, the strength of which depends mainly on the rate of fall of the parachutist at the time of the opening of the parachute canopy and on the time of the opening of the parachute.
The necessary opening time of the parachute, as well as the uniform distribution of overload is provided by its design. In amphibious and special-purpose parachutes, this function in most cases is performed by a camera (case) put on the canopy.
Sometimes, when opening a parachute, a parachutist experiences six to eight times overload within 1 - 2 s. The tight fit of the parachute suspension system, as well as the correct grouping of the body, contributes to reducing the impact of the dynamic impact force on the paratrooper.
When descending, the parachutist moves, in addition to the vertical, in the horizontal direction. Horizontal movement depends on the direction and strength of the wind, the design of the parachute and the symmetry of the canopy during descent. On a parachute with a round canopy, in the absence of wind, the parachutist descends strictly vertically, since the pressure of the air flow is distributed evenly over the entire inner surface of the canopy. An uneven distribution of air pressure over the surface of the dome occurs when its symmetry is affected, which is carried out by tightening certain lines or free ends of the suspension system. Changing the symmetry of the dome affects the uniformity of its air flow. The air escaping from the side of the raised part creates a reactive force, as a result of which the parachute moves (slides) at a speed of 1.5 - 2 m / s.
Thus, in calm weather, for horizontal movement of a parachute with a round dome in any direction, it is necessary to create a glide by pulling and holding in this position the lines or free ends of the harness located in the direction of the desired movement.
Among special-purpose parachutes, parachutes with a round dome with slots or a wing-shaped dome provide horizontal movement at a sufficiently high speed, which allows the paratrooper to turn the canopy to achieve great accuracy and landing safety.
On a parachute with a square canopy, horizontal movement in the air is due to the so-called large keel on the canopy. The air coming out from under the dome from the side of the large keel creates a reactive force and causes the parachute to move horizontally at a speed of 2 m/s. The skydiver, having turned the parachute in the desired direction, can use this property of the square canopy for a more accurate landing, to turn into the wind, or to reduce the landing speed.
In the presence of wind, the landing speed is equal to the geometric sum of the vertical component of the rate of descent and the horizontal component of the wind speed and is determined by the formula
V pr = V 2 sn + V 2 3, (2)
where V3 - wind speed near the ground.
It must be remembered that vertical air flows significantly change the rate of descent, while descending air flows increase the landing speed by 2–4 m/s. Updrafts, on the contrary, reduce it.
Example:The paratrooper's descent speed is 5 m/s, the wind speed near the ground is 8 m/s. Determine the landing speed in m/s.
Solution: V pr \u003d 5 2 +8 2 \u003d 89 ≈ 9.4
The final and most difficult stage of a parachute jump is landing. At the moment of landing, the parachutist experiences a blow to the ground, the strength of which depends on the speed of descent and on the speed of loss of this speed. In practice, slowing down the loss of speed is achieved by a special grouping of the body. When landing, the paratrooper is grouped so as to first touch the ground with their feet. The legs, bending, soften the force of impact, and the load is distributed evenly over the body.
Increasing the parachutist's landing speed due to the horizontal component of the wind speed increases the ground impact force (R3). The force of impact on the ground is found from the equality of the kinetic energy possessed by a descending paratrooper, the work produced by this force:
m P v 2 = R h l c.t. , (3)
2
where
R h = m P v 2 = m P ( v 2 sn + v 2 h ) , (4)
2 l c.t. 2 l c.t.
Where l c.t. - the distance from the paratrooper's center of gravity to the ground.
Depending on the conditions of landing and the degree of training of the parachutist, the magnitude of the impact force can vary over a wide range.
Example.Determine the impact force in N of a skydiver weighing 80 kg, if the descent speed is 5 m/s, the wind speed near the ground is 6 m/s, the distance from the center of gravity of the paratrooper to the ground is 1 m.
Solution: R h = 80 (5 2 + 6 2 ) = 2440 .
2 . 1
The impact force during landing can be perceived and felt by a skydiver in different ways. It depends to a large extent on the condition of the surface on which he lands, and how he prepares himself to meet the ground. So, when landing on deep snow or on soft ground, the impact is significantly softened compared to landing on hard ground. In the case of a swinging paratrooper, the impact force upon landing increases, since it is difficult for him to take the correct body position to receive the blow. Swing must be extinguished before approaching the ground.
With the correct landing, the loads experienced by the paratrooper paratrooper are small. It is recommended to evenly distribute the load when landing on both legs to keep them together, bent so that under the influence of the load they can, spring, bend further. The tension of the legs and body must be maintained uniform, while the greater the landing speed, the greater the tension should be.
2.4. GENERAL INFORMATION ABOUT amphibious
PARACHUTE SYSTEMS
Purpose and composition. A parachute system is one or more parachutes with a set of devices that ensure their placement and fastening on an aircraft or a dropped load and the activation of parachutes.
The qualities and merits of parachute systems can be assessed based on the extent to which they meet the following requirements:
Maintain any speed possible after the paratrooper leaves the aircraft;
The physical essence of the function performed by the dome during its descent is to deflect (push) the particles of oncoming air and rub against it, while the dome carries some of the air with it. In addition, the parted air does not close directly behind the dome, but at some distance from it, forming vortices, i.e. rotational movement of air streams. When the air is pushed apart, friction against it, entrainment of air in the direction of movement and the formation of vortices, work is performed, which is performed by the air resistance force. The magnitude of this force is mainly determined by the shape and size of the parachute canopy, the specific load, the nature and airtightness of the fabric of the canopy, the rate of descent, the number and length of lines, the method of attaching the lines to the load, the removal of the canopy from the load, the design of the canopy, the size of the pole hole or valves, and others. factors.
The drag coefficient of a parachute is usually close to that of a flat plate. If the surfaces of the dome and the plate are the same, then the resistance will be greater at the plate, because its midsection is equal to the surface, and the midsection of the parachute is much less than its surface. The true diameter of the canopy in the air and its midsection are difficult to calculate or measure. The narrowing of the parachute canopy, i.e. the ratio of the diameter of the filled dome to the diameter of the deployed dome depends on the shape of the fabric cutting, the length of the lines and other reasons. Therefore, when calculating the resistance of a parachute, it is always not the midsection that is taken into account, but the surface of the dome - a value that is precisely known for each parachute.
Dependency C P from the shape of the dome. Air resistance to moving bodies depends largely on the shape of the body. The less streamlined the shape of the body, the more resistance the body experiences when moving in the air. When designing a parachute canopy, a dome shape is sought that, with the smallest dome area, would provide the greatest resistance force, i.e. with a minimum surface area of the parachute dome (with a minimum consumption of material), the shape of the dome should provide the cargo with a given landing speed.
The tape dome, for whichFROMn \u003d 0.3 - 0.6, for a round dome it varies from 0.6 to 0.9. The square-shaped dome has a more favorable ratio between the midship and the surface. In addition, the flatter shape of such a dome, when lowered, leads to increased vortex formation. As a result, a parachute with a square dome hasFROMn = 0.8 - 1.0. An even greater value of the drag coefficient for parachutes with a retracted top of the canopy or with canopies in the form of an elongated rectangle, so with a canopy aspect ratio of 3: 1FROM n = 1.5.
Glide due to the shape of the parachute canopy also increases the drag coefficient to 1.1 - 1.3. This is explained by the fact that when sliding, the dome is flown by air not from the bottom up, but from the bottom to the side. With such a flow around the dome, the rate of descent as a resultant is equal to the sum of the vertical and horizontal components, i.e. due to the appearance of horizontal displacement, the vertical one decreases (Fig. 3).
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increases by 10 - 15%, but if the number of lines is more than necessary for a given parachute, then it decreases, since with a large number of lines the canopy inlet is blocked. Increasing the number of canopy lines beyond 16 does not cause a noticeable increase in midsection; the midsection of the canopy with 8 lines is noticeably smaller than the midsection of the canopy with 16 lines
(Fig. 4).
The number of canopy lines is determined by the length of its lower edge and the distance between the lines, which for the canopies of the main parachutes is 0.6 - 1 m. The exception is stabilizing and braking parachutes, in which the distance between two adjacent lines is 0.05 - 0.2 m, in due to the fact that the length of the lower edge of their domes is relatively short and it is impossible to attach a large number of lines necessary to increase strength.
AddictionFROM P from the length of the dome lines . The parachute canopy takes shape and balances if, at a certain length of the line, the lower edge is pulled together under the action of a forceR.When reducing the length of the sling, the angle between the sling and the axis of the domea increases ( a 1 > a), the contracting force also increases (R 1 >P). Under the forceR 1 the edge of the canopy with short lines is compressed, the midsection of the canopy becomes smaller than the midsection of the canopy with long lines (Fig. 5). Reducing the midsection leads to a decrease in the coefficientFROMn, and the equilibrium of the dome is disturbed. With a significant shortening of the lines, the dome takes on a streamlined shape, partially filled with air, which leads to a decrease in pressure drop and, consequently, to an additional decrease in С P . Obviously, it is possible to calculate such a length of lines at which the canopy cannot be filled with air.
Increasing the length of the lines increases the resistance coefficient of the ku-floor C P and, therefore, provides a given landing or descent speed with the smallest possible canopy area. However, it should be remembered that an increase in the length of the lines leads to an increase in the mass of the parachute.
It has been experimentally established that with an increase in the length of the lines by a factor of 2, the drag coefficient of the dome increases only by a factor of 1.23. Therefore, by increasing the length of the lines by 2 times, it is possible to reduce the area of the dome by 1.23 times. In practice, they use a length of lines equal to 0.8 - 1.0 of the diameter of the dome in the cut, although calculations show that the largest valueFROM P reaches with a length of lines equal to three diameters of the dome in the cut.
High resistance is the main, but not the only requirement for a parachute. The shape of the dome should ensure its rapid and reliable opening, stable, without swaying, lowering. In addition, the dome must be durable and easy to manufacture and operate. All of these requirements are in conflict. For example, domes with high resistance are very unstable, and, conversely, very stable domes have little resistance. When designing, these requirements are taken into account depending on the purpose of the parachute systems.
Operation of the landing parachute system. The sequence of operation of the landing parachute system in the initial period is determined primarily by the aircraft's flight speed during landing.
As you know, with increasing speed, the load on the canopy of the parachute increases. This makes it necessary to increase the strength of the canopy, as a result, to increase the mass of the parachute and take protective measures to reduce the dynamic load on the body of the paratrooper at the time of opening the main parachute canopy.
The operation of the landing parachute system has the following stages:
I - descent on the stabilizing parachute system from the moment of separation from the aircraft until the introduction of the main parachute;
II – the exit of the lines from the honeycombs and the dome from the chamber of the main parachute;
III - filling the canopy of the main parachute with air;
IV - dampening of the system speed from the end of the third stage until the system reaches a steady rate of descent.
The introduction of the parachute system begins at the moment of separation of the parachutist from the aircraft with the sequential inclusion of all elements of the parachute system.
To streamline the opening and ease of packing the main parachute, it is placed in a parachute chamber, which, in turn, fits into a satchel, which is attached to the suspension system. The landing parachute system is attached to the paratrooper with the help of a suspension system, which allows you to conveniently place the packed parachute and evenly distribute the dynamic load on the body during the filling of the main parachute.
Serial landing parachute systems are designed to perform jumps from all types of military transport aircraft at high flight speeds. The main parachute is put into action a few seconds after the separation of the paratrooper from the aircraft, which ensures the minimum load acting on the parachute canopy when it is filled, and allows you to get out of the disturbed air flow. These requirements determine the presence of a stabilizing parachute in the landing system, which ensures stable movement and reduces the initial rate of descent to the optimally required one.
Upon reaching a predetermined height or after a set descent time, the stabilizing parachute is disconnected from the main parachute pack using a special device (manual deployment link or parachute device), drags the main parachute chamber with the main parachute stowed in it and puts it into action. In this position, the parachute canopy is filled without jerks, at an acceptable speed, which ensures its reliability in operation, and also reduces the dynamic load.
The steady rate of vertical descent of the system gradually decreases due to the increase in air density and reaches a safe speed at the moment of landing.
See also Spetsnaz.org.