Aircraft durability test. How airplanes are tested for strength. Preparation of test report

The creation of any aircraft is a long and complex process, the result of the joint efforts of a huge team, many divisions and departments. The Ilyushin Aviation Complex, along with the experimental design bureau, also includes a large number of structural laboratories necessary for conducting full-fledged tests, including very important tests for the future aircraft - structural strength tests. In the course of static and life tests of full-scale samples of prototype products, the calculated conclusions are confirmed experimentally. The tests confirm the correctness of the design of the structure for the given loads, and the question of the correctness of determining the loads is solved with the help of flight strength tests, which are already carried out by specialists at the FRI with the participation of specialists from the department. Today we will take a closer look at just such a complex. Vladimir Ivanovich Tkachenko, the deputy head of the laboratory of the complex of strength tests "AK named after S.V. Ilyushin", candidate of technical sciences, met us and gave us a tour...
Vladimir Ivanovich spoke about the types of strength tests, and specifically about the studies that are carried out in this laboratory. There are two independent disciplines of strength calculations - calculation of strength for statics and calculation for a resource. Static tests, in which the load on the elements of the airframe exceeds the operational one by 1.5 times. Wing load during flight exceeds 1000 tons. Create the most approximate conditions of the structure due to the stress-strain state of the structure. The operational load in the calculations is assumed to be 67% (this is out of airworthiness standards). If, for example, we multiply this value by the safety factor (for calculations, the value is taken - 1.5, which takes into account the life of the airframe), then exactly 100% of the calculated load is obtained, although such a load never occurs during the flight ...
The wing, as the most damaged part of the aircraft structure, is tested with design loads up to 120%. The fuselage, although it has various structural cutouts and cavities, and it would seem that it should have less strength, is not subject to such loads in flight as the wing receives. Therefore, testing with 100% load is enough for him ...
This Il-76TD (RA-76751), released in 1988, first flew in Aeroflot and managed to fly 2,500 hours, and in 1994, after landing on the Khodynka field, it came into the possession of the Design Bureau for the installation and flight of new PS- 90. However, the engines were never installed on this car, and it was decided to leave this board for life testing. For this, a special program was developed. According to a similar program, life tests of the Il-476 are now being carried out ...
IL-76 was originally designed for 20,000 flights. But in order to provide him with such characteristics, it was necessary to carry out the whole complex of strength, and then life tests. And then, to this day, continue to conduct tests already to ensure the extension of the resource ...
It is these studies that are carried out in this laboratory. The landing gear has been removed from the aircraft. The aircraft is suspended under powerful beams on special suspensions, which also include hydraulic cylinders that can create a load of tens of tons on a structural element. The automatic tracking system, developed jointly with TsAGI, allows you to stabilize the suspension and provide the desired flight condition. The forces of these hydraulic cylinders are proportional to their diameters. The load with the help of additional beams and brackets is evenly distributed over the structural elements. Pylons for standard D-30 engines were left on the left half-span of the wing, while pylons and reinforced structural elements and attachment points for PS-90 engines, which are heavier and more powerful than the 30s, were installed on the right half-span ...
On average, to determine the resource, a flight lasting 3-4 hours and a service life of 20-25 years are taken into account. These values ​​are confirmed first. In the future, to increase the resource, they begin to conduct additional tests, which can last for years. Usually, the resource according to the state of the material (corrosion, fatigue, wear) is less than according to flights, and it is more difficult to extend such a resource. Now, according to the results of tests, the service life of flying Il-76 with D-30 engines has been extended to 10,000 hours ...
A program flight usually lasts 20 minutes and is performed with full load on the structural elements of the wing and fuselage (wing loads are performed with a safety factor of 2). The wing is subjected to pressure and various vibrations through the action of hydraulic cylinders. The load for the calculation is summed from all cylinders. At the final stage of the flight, the wing is subjected to pressure loads that simulate a landing. According to the program, which is now being worked out on the 76th, it is necessary to perform 20,000 such flights ...
If damage occurs, the tests are stopped and the assembly is repaired. After that, the testing process is resumed. Damage to the structure and individual elements is detected in various ways, both visual (if large) and instrumental (there are several special methods) that can find even minimal cracks ... Usually, the further the resource is extended, the more restrictions are imposed on the operation of the aircraft. For example, they restrict flights due to weather conditions or transfer from passenger flights to cargo transportation ...
We also looked inside the plane. To create a load on the floor, ring weights are laid in various places ...
The place of the navigator and again the loads on the floor ...
Wire harnesses from sensors of measuring equipment are stretched throughout the cabin ...
View of the wing through the porthole, entangled in a network of beams, brackets and wires...
The study of the insides of the aircraft was not without an attentive local "controller";)
If cracks are found, their fixation or elimination is now possible with the help of adhesive methods, the so-called "stoppers". Such innovations began with the creation and testing of the wing for the Il-86, which, during development, required different, higher, strength characteristics ...
Today, a very large number of Il-76s are still in operation around the world, including those of foreign operators, which in turn requires additional research on the resource. Therefore, these types of strength tests for this machine will continue further ... Below are two new pylons for PS-90 engines, handed over by the plant for installation and strength testing...
The entire wing is hung with various levers and counterweights, combined into one common complex system... From this cab, located a few meters above the floor, the operator controls the test programs. There are two such cabins in the hangar...
Well, then we got acquainted with another amazing aircraft - a wooden full-size model of the Il-96-300, created mainly to solve problems in the layout of the cabin.
Even part of the wing and the engine are recreated on the mock-up...
Not only the interior, but also the external design features are modeled in sufficient detail...
Having climbed on board, the first thing we do is look into the cockpit, because it is also available in this layout...
Inside, at first glance, everything looks like in the real 96th. Differences become noticeable only upon closer examination. For the manufacture, in most cases, wood and plywood were used. Although, in some places, real interior trim elements are also installed ...
There are several salons, as in real Il. There is plenty of free space inside. They say that this layout was also used in the development of the interior equipment of the presidential IL-96 ...
On the frame below - the 103rd machine (five-seater IL-103), which has already passed the entire scope of tests, and is now also in this department, sheltered next to its older sister ...
And finally, another general view of the laboratory...

The creation of any aircraft is a long and complex process, the result of the joint efforts of a huge team, many divisions and departments. The Ilyushin Aviation Complex, along with the experimental design bureau, also includes a large number of structural laboratories necessary for conducting full-fledged tests, including very important tests for the future aircraft - structural strength tests.

1. (clickable up to 1400)

In the course of static and life tests of full-scale samples of prototype products, the calculated conclusions are confirmed experimentally. The tests confirm the correctness of the design of the structure for the given loads, and the question of the correctness of determining the loads is solved with the help of flight strength tests, which are already carried out by specialists at the FRI with the participation of specialists from the department. Today we will take a closer look at just such a complex.


Vladimir Ivanovich Tkachenko, the deputy head of the laboratory of the complex of strength tests "AK named after S.V. Ilyushin", candidate of technical sciences, met us and gave us a tour...
2.

Vladimir Ivanovich spoke about the types of strength tests, and specifically about the studies that are carried out in this laboratory.

There are two independent disciplines of strength calculations - calculation of strength for statics and calculation for a resource. Static tests, in which the load on the elements of the airframe exceeds the operational one by 1.5 times. Wing load during flight exceeds 1000 tons. Create the most approximate conditions of the structure due to the stress-strain state of the structure.

The operational load in the calculations is assumed to be 67% (this is out of airworthiness standards). If, for example, we multiply this value by the safety factor (for calculations, the value is taken - 1.5, which takes into account the life of the airframe), then exactly 100% of the calculated load is obtained, although such a load never occurs during the flight ...
3.

The wing, as the most damaged part of the aircraft structure, is tested with design loads up to 120%. The fuselage, although it has various structural cutouts and cavities, and it would seem that it should have less strength, is not subject to such loads in flight as the wing receives. Therefore, testing with 100% load is enough for him ...
4.

This Il-76TD (RA-76751), released in 1988, first flew in Aeroflot and managed to fly 2,500 hours, and in 1994, after landing on the Khodynka field, it came into the possession of the Design Bureau for the installation and flight of new PS- 90.
However, the engines were never installed on this car, and it was decided to leave this board for life testing. For this, a special program was developed. According to a similar program, life tests of the Il-476 are now being carried out ...
5.

IL-76 was originally designed for 20,000 flights. But in order to provide him with such characteristics, it was necessary to carry out the whole complex of strength, and then life tests. And then, to this day, continue to conduct tests already to ensure the extension of the resource ...
6.

It is these studies that are carried out in this laboratory. The landing gear has been removed from the aircraft. The aircraft is suspended under powerful beams on special suspensions, which also include hydraulic cylinders that can create a load of tens of tons on a structural element. The automatic tracking system, developed jointly with TsAGI, allows you to stabilize the suspension and provide the desired flight condition.

The forces of these hydraulic cylinders are proportional to their diameters. The load with the help of additional beams and brackets is evenly distributed over the structural elements. Pylons for standard D-30 engines were left on the left half-span of the wing, while pylons and reinforced structural elements and attachment points for PS-90 engines, which are heavier and more powerful than the 30s, were installed on the right half-span ...
7.

On average, to determine the resource, a flight lasting 3-4 hours and a service life of 20-25 years are taken into account. These values ​​are confirmed first. In the future, to increase the resource, they begin to conduct additional tests, which can last for years. Usually, the resource according to the state of the material (corrosion, fatigue, wear) is less than according to flights, and it is more difficult to extend such a resource. Now, according to the test results, the service life of flying Il-76 with D-30 engines has been extended to 10,000 hours ...
8.

A program flight usually lasts 20 minutes and is performed with full load on the structural elements of the wing and fuselage (wing loads are performed with a safety factor of 2). The wing is subjected to pressure and various vibrations through the action of hydraulic cylinders. The load for the calculation is summed from all cylinders. At the final stage of the flight, the wing is subjected to pressure loads that simulate a landing. According to the program, which is now being worked out on the 76th, it is necessary to perform 20,000 such flights ...
9.

If damage occurs, the tests are stopped and the assembly is repaired. After that, the testing process is resumed. Damage to the structure and individual elements is detected in various ways, both visual (if large) and instrumental (there are several special methods) that can find even minimal cracks ...
10.

Usually, the further the resource is extended, the more restrictions are imposed on the operation of the aircraft. For example, they restrict flights due to weather conditions or transfer from passenger flights to cargo transportation ...
11.

We also looked inside the plane. To create a load on the floor, ring weights are laid in various places ...
12.

The place of the navigator and again the loads on the floor ...
13.

Wire harnesses from sensors of measuring equipment are stretched throughout the cabin ...
14.

View of the wing through the porthole, entangled in a network of beams, brackets and wires...
15.

The study of the insides of the aircraft was not without an attentive local "controller";)
16.

If cracks are found, their fixation or elimination is now possible with the help of adhesive methods, the so-called "stoppers". Such innovations began with the creation and testing of the wing for the Il-86, which, during development, required different, higher, strength characteristics ...
17.

Today, a very large number of Il-76s are still in operation around the world, including those of foreign operators, which in turn requires additional research on the resource. Therefore, these types of strength tests for this machine will continue further ...
18.

Below are two new pylons for PS-90 engines, handed over by the plant for installation and strength testing...
19.

The entire wing is hung with various levers and counterweights, combined into one common complex system...
20.

From this cab, located a few meters above the floor, the operator controls the test programs.
There are two such cabins in the hangar...
21.

Well, then we got acquainted with another amazing aircraft - a wooden full-size model of the Il-96-300, created mainly to solve problems in the layout of the cabin.
22.

Even part of the wing and the engine are recreated on the mock-up...
23.

Not only the interior, but also the external design features are modeled in sufficient detail...
24.

Having climbed on board, the first thing we do is look into the cockpit, because it is also available in this layout...
25.

Inside, at first glance, everything looks like in the real 96th. Differences become noticeable only upon closer examination. For the manufacture, in most cases, wood and plywood were used. Although, in some places, real interior trim elements are also installed ...
26.

There are several salons, as in real Il. There is plenty of free space inside. They say that this layout was also used in the development of the interior equipment of the presidential IL-96 ...
27.

On the frame below - the 103rd machine (five-seater IL-103), which has already passed the entire scope of tests, and is now also in this department, sheltered next to its older sister ...
28.

And finally, another general view of the laboratory...
29.
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There are two types of aircraft testing:
First type.
Factory testing includes:

  • testing of prototype aircraft;
  • testing of serial lead aircraft;
  • serial aircraft testing;
  • acceptance tests.

Second type.
State tests - they include:

  • testing of prototype aircraft;
  • tests of serial aircraft (military tests are carried out for military vehicles).

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Factory testing of prototype aircraft

The purpose of these tests is to determine the tactical and flight properties of the aircraft, as well as the compliance of these properties with the calculated ones, according to the data of the design bureau (KB). the test program allows you to determine the flight and operational characteristics of the entire aircraft, as well as to check the operation of its main units.
The test is carried out by employees of the factory flight test station. The brigade consists of a lead pilot, a lead engineer, special services specialists and on-board technicians. The team monitors the entire process of building a prototype aircraft from start to finish. Prior to the start of the plant, submits the following documents to the testing station:

  • Calculation of aircraft aerodynamics;
  • Calculation of the aircraft for stability;
  • Calculation of aircraft strength.

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Preparatory work before the first flight

As soon as the aircraft is delivered to the flight test station, preparations for the first flight begin. The preparation process consists of the following steps:

  • aircraft assembly and leveling in accordance with design bureau drawings;
  • control measurements of the aircraft for compliance with the design bureau drawings;
  • weighing and determining the center of gravity of the aircraft;
  • determination of the most favorable balance for the first departure;
  • checking the operation of aircraft units;
  • aircraft braking group adjustment;
  • verification of the work of the governing bodies;
  • experimental races without takeoff - in order to test the steering wheel and brakes at speeds up to 30 km / h;
  • checking the operation of the tail rudders at speeds up to 50 km/h;
  • checking the operation of the chassis;
  • if the area of ​​the test airfield allows, then control take-offs are carried out at a height of 1-2m.

After all the preparatory work, the prototype aircraft is ready for the first flight.

First flight

The first flight of the aircraft is appointed only after the elimination of all defects identified in the ground tests. It is conducted by the lead pilot. The result of the first flight is the determination of the following defects and properties of the aircraft:

  • aircraft takeoff smoothness;
  • the presence of vibrations of the body and units;
  • the presence of deformations, bends and twisting in the elements of the fuselage, wings and tail elements;
  • operation of units and equipment in various modes;
  • operation of controls at various speeds;
  • main indicators of units (engine temperature, oil level, water temperature, engine speed)
  • smooth operation of the motor;
  • fuel consumption in different flight modes;
  • the position of the stabilizers during landing;
  • landing run length;
  • operation of the brake system.

After the first flight, 10-15 more flights are carried out in order to fine-tune the aircraft. Usually, in order to be sure of the safety of further operation, the aircraft is tested at speeds exceeding the design allowable.

Tests of lead production aircraft

Lead production aircraft are the first two aircraft of the new series. The test program for these aircraft consists of the following stages:

  • determination of the aircraft ceiling and rise time to different heights;
  • determination of landing speed and maximum speeds at different altitudes;
  • determination of aircraft controllability at various altitudes;
  • determination of engine operation modes under various loads;
  • determination of fuel consumption and flight range at optimum speed;
  • checking the operation of aircraft instruments and assemblies;
  • determination of the time and length of the acceleration of the aircraft.

Equipment and apparatus for testing lead production aircraft does not differ from that used in testing prototype aircraft.

Production aircraft testing

Such tests of aircraft are carried out by special commissions, which include representatives of customer services. The number of aircraft approved for flight testing is specified in the contract. Usually no more than ten production aircraft

Tests of multi-engine aircraft

The difference between this type of test is the inclusion of the following two items in the flight program:

  1. aircraft control in case of failure of one or more engines;
  2. determination of the maximum flight altitude for various combinations of engines.

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Preparation of test report

When the aircraft has completely passed the entire test program, a test report is prepared. It consists of several sections:

  • Flight and weight characteristics of the aircraft and equipment;
  • A list of all changes and refinements made during the testing process;
  • Analysis of the compliance of flight characteristics with the design data required for this type of aircraft;
  • Comparison of the aircraft with foreign counterparts;
  • Conclusions and recommendations of the flight test station.

The report is compiled by the lead engineer of the flight test station and signed by all the specialists who took part in the tests. After the report is approved, the aircraft is presented for state testing.
The aircraft is accompanied by the following documentation:

  • calculation of aerodynamics;
  • stability calculation;
  • strength calculation;
  • aircraft test materials;
  • aircraft equipment diagrams;
  • technical description of the aircraft (compiled by representatives of the Design Bureau).

State tests

Such tests are carried out if the aircraft was designed and built according to the state order. The purpose of these tests is:

  • verification of aircraft compliance with tactical and technical requirements;
  • detection of defects in aircraft design and equipment.

The state testing program consists of the following stages:

  • familiarization flights;
  • instrument calibration;
  • flights to determine the optimal flight mode;
  • flights to determine stability at various loads on;
  • determination of lifting speed, ceiling and fuel consumption;
  • definition of maneuverability;
  • night flights and blind flights;
  • pr and takeoff and landing;

The creation of any aircraft is a long and complex process, the result of the joint efforts of a huge team, many divisions and departments. The Ilyushin Aviation Complex, along with the experimental design bureau, also includes a large number of structural laboratories necessary for conducting full-fledged tests, including very important tests for the future aircraft - structural strength tests.

In the course of static and life tests of full-scale samples of prototype products, the calculated conclusions are confirmed experimentally. The tests confirm the correctness of the design of the structure for the given loads, and the question of the correctness of determining the loads is solved with the help of flight strength tests, which are already carried out by specialists at the FRI with the participation of specialists from the department. Today we will take a closer look at just such a complex.

We were met and given a tour by the deputy head of the laboratory of the complex of strength tests "AK named after S.V. Ilyushin", candidate of technical sciences - Vladimir Ivanovich Tkachenko ...

Vladimir Ivanovich spoke about the types of strength tests, and specifically about the studies that are carried out in this laboratory.

There are two independent disciplines of strength calculations - static strength calculation and resource calculation. Static tests, in which the load on the elements of the airframe exceeds the operational one by 1.5 times. Wing load during flight exceeds 1000 tons. Create the most approximate conditions of the structure due to the stress-strain state of the structure.

The operational load in the calculations is assumed to be 67% (this is out of airworthiness standards). If, for example, this value is multiplied by the safety factor (for calculations, the value of 1.5 is taken, which takes into account the life of the airframe), then exactly 100% of the calculated load is obtained, although such a load never occurs during the flight ...

The wing, as the most damaged part of the aircraft structure, is tested with design loads up to 120%. The fuselage, although it has various structural cutouts and cavities, and it would seem that it should have less strength, is not subject to such loads in flight as the wing receives. Therefore, testing with 100% load is enough for him ...

This Il-76TD (RA-76751), released in 1988, first flew in Aeroflot and managed to fly 2,500 hours, and in 1994, after landing on the Khodynka field, it came into the possession of the design bureau for the installation and flight of new PS- 90.

However, the engines were never installed on this car, and it was decided to leave this board for life testing. For this, a special program was developed. According to a similar program, life tests of the Il-476 are now being carried out ...

IL-76 was originally designed for 20,000 flights. But in order to provide him with such characteristics, it was necessary to carry out the whole complex of strength, and then life tests. And then, to this day, continue to conduct tests already to ensure the extension of the resource ...

It is these studies that are carried out in this laboratory. The landing gear has been removed from the aircraft. The aircraft is suspended under powerful beams on special suspensions, which also include hydraulic cylinders that can create a load of tens of tons on a structural element. The automatic tracking system, developed jointly with TsAGI, allows you to stabilize the suspension and provide the desired flight condition.

The forces of these hydraulic cylinders are proportional to their diameters. The load with the help of additional beams and brackets is evenly distributed over the structural elements. Pylons for standard D-30 engines were left on the left half-span of the wing, while pylons and reinforced structural elements and attachment points for PS-90 engines, which are heavier and more powerful than the 30s, were installed on the right half-span.

On average, to determine the resource, a flight lasting 3-4 hours and a service life of 20-25 years are taken into account. These values ​​are confirmed first. In the future, to increase the resource, they begin to conduct additional tests, which can last for years. Usually, the resource according to the state of the material (corrosion, fatigue, wear) is less than according to flights, and it is more difficult to extend such a resource. Now, according to the results of tests, the service life of flying Il-76 with D-30 engines has been extended to 10,000 hours ...

A program flight usually lasts 20 minutes and is performed with full load on the structural elements of the wing and fuselage (wing loads are performed with a safety factor of 2). The wing is subjected to pressure and various vibrations through the action of hydraulic cylinders. The load for the calculation is summed from all cylinders. At the final stage of the flight, the wing is subjected to pressure loads that simulate a landing. According to the program, which is now being worked out on the 76th, it is necessary to perform 20,000 such flights ...

If damage occurs, the tests are stopped and the assembly is repaired. After that, the testing process is resumed. Damage to the structure and individual elements is detected in various ways, both visual (if large) and instrumental (there are several special methods) that can find even minimal cracks ...

Usually, the further the resource is extended, the more restrictions are imposed on the operation of the aircraft. For example, they restrict flights due to weather conditions or transfer from passenger flights to cargo transportation ...

We also looked inside the plane. To create a load on the floor, ring weights are laid in various places ...


The place of the navigator and again the loads on the floor ...


Wire harnesses from instrumentation sensors are stretched throughout the cabin ...


View of the wing through the porthole, entangled in a network of beams, brackets and wires ...


The study of the insides of the aircraft was not without an attentive local "controller";)


If cracks are found, their fixation or elimination is now possible with the help of adhesive methods, the so-called "stoppers". Such innovations began with the creation and testing of the wing for the Il-86, which, during development, required other, higher, strength characteristics ...

Today, a very large number of Il-76s are still in operation around the world, including those of foreign operators, which in turn requires additional research on the resource. Therefore, these types of strength tests for this machine will continue further ...

Below are two new pylons for PS-90 engines, handed over by the plant for installation and strength testing ...

The entire wing is hung with various levers and counterweights, combined into one common complex system ...

From this cab, located a few meters above the floor, the operator controls the test programs.
There are two such cabins in the hangar ...



Even part of the wing and the engine are recreated on the mock-up...


Not only the interior, but also the external design features are modeled in sufficient detail ...


Having climbed on board, the first thing we look into is the cockpit, because it is also available in this layout ...


Inside, at first glance, everything looks like in the real 96th. Differences become noticeable only upon closer examination. For the manufacture, in most cases, wood and plywood were used. Although, in some places, real interior trim elements are also installed ...

There are several salons, as in real Il. There is plenty of free space inside. They say that this model was also used in the development of the interior equipment of the presidential IL-96 cabin ...

On the frame below - the 103rd machine (five-seater IL-103), which has already passed the entire scope of tests, and is now also in this department, sheltered next to its older sister ...

And finally, another general view of the laboratory...


 

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