Aircraft static tests. Aircraft testing process

There are two types of aircraft testing:
First type.
Factory tests - these include:

testing of prototype aircraft;
testing of lead production aircraft;
testing of production aircraft;
acceptance tests.

Second type.
State tests - they include:

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

Science 2.0. Anatomy of monsters. Airplane

Factory tests of prototype aircraft

The purpose of these tests is to determine the tactical and flight properties of the aircraft, as well as the correspondence of these properties to the calculated ones, according to data from the design bureau (KB). The test program makes it possible to determine the flight and operational characteristics of the entire aircraft, as well as to check the operation of its main components.
The test is carried out by employees of the factory flight test station. The brigade consists of a leading pilot, a leading engineer, special services specialists and an on-board technician. The team monitors the entire process of building a prototype aircraft from start to finish. Before starting the plant, the following documents are submitted to the testing station:

Calculation of aircraft aerodynamics;
Aircraft stability calculations;
Calculation of aircraft strength.

T-50. Stealth plane

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 stages:

assembly and leveling of the aircraft in accordance with the design bureau drawings;
control measurements of the aircraft for compliance with design bureau drawings;
weighing and determining the center of gravity of the aircraft;
determining the most favorable alignment for the first flight;
checking the operation of aircraft components;
adjustment of the aircraft brake group;
checking the operation of controls;
test runs without takeoff - to check 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 1-2 m.

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

First flight

The first flight of the aircraft is scheduled only after all defects identified during ground tests have been eliminated. 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:

smooth takeoff of the aircraft;
presence of vibrations of the housing 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 different speeds;
main indicators of units (engine temperature, oil level, water temperature, engine speed)
smooth operation of the motor;
fuel consumption under different flight modes;
position of stabilizers during landing;
landing run length;
operation of the braking system.

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

Testing of the leading production aircraft

Head ones serial aircraft– these are the first two aircraft of the new series. The test program for these aircraft consists of the following stages:

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

The equipment and equipment for testing the lead production aircraft does not differ from that used when testing prototype aircraft.

Testing of production aircraft

Such aircraft tests 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. Typically no more than ten production aircraft

Multi-engine aircraft testing

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

control of the aircraft when one or more engines fail;
determination of maximum flight altitude for various engine combinations.

The most famous fighters of the MIG family

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 improvements made during the testing process;
Analysis of compliance of flight characteristics with the design data required for this type of aircraft;
Comparison of the aircraft with foreign analogues;
Conclusions and recommendations from the flight test station.

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

aerodynamics calculation;
stability calculation;
strength calculation;
aircraft testing 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 under government order. The purpose of these tests is:

checking the aircraft's compliance with tactical and technical requirements;
identifying defects in the design and equipment of the aircraft.

The state testing program consists of the following stages:

familiarization flights;
instrument calibration;
flights to determine the optimal flight mode;
flights to determine stability under various loads on;
determination of lifting speed, ceiling and fuel consumption;
determination of maneuverability;
night flights and blind flights;
during 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 tests, including tests of structural strength that are very important for the future aircraft.

During static and life tests of full-scale prototypes of experimental products, the calculated conclusions are confirmed experimentally. The tests confirm the correctness of the design of the structure for the given loads, and the issue of the correctness of determining the loads is resolved with the help of flight strength tests, which are carried out by specialists at the LII with the participation of specialists from the department. Today we’ll 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 strength testing complex "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 research that is carried out in this laboratory.

There are two independent disciplines of strength calculations - static strength calculations and resource calculations. Static tests, during which the load on the airframe elements exceeds the operational load by 1.5 times. The load on the wing 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 outside the airworthiness standards). If, for example, we multiply this value by the safety factor (for calculations the value is taken to be 1.5, which takes into account the life of the airframe), then we get exactly the 100% design load, although such a load never occurs during flight...

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

This Il-76TD (RA-76751), produced in 1988, first flew for Aeroflot and managed to fly 2,500 hours, and in 1994, after landing on Khodynskoye Field, it was placed at the disposal of the Design Bureau for installation and flight testing of new PS- engines. 90.
However, the engines were never installed on this vehicle, and it was decided to leave this side for life testing. A special program was developed for this purpose. Life tests of the Il-476 are now being carried out under a similar program...

The IL-76 was initially designed for 20,000 flights. But in order to provide it with such characteristics, it was necessary to carry out a full range of strength and then life tests. And then, to this day, continue to carry out tests to ensure service life extension...

This is exactly the kind of research that is carried out in this laboratory. The landing gear has been removed from the plane. 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 ensure the desired flight condition.

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

On average, to determine the service life, 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. Typically, the service life due to the condition of the material (corrosion, fatigue, wear) is less than that due to flights, and it is more difficult to extend such a service life. Now, based on test results, the flying Il-76 with D-30 engines has had its service life extended to 10,000 hours...

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

If damage occurs, testing is stopped and the unit is repaired. After this, the testing process resumes. Damage to the structure and individual elements is detected in various ways, both visual (if large) and instrumental (there are several special techniques), capable of finding even minimal cracks...

Typically, the further the service life is extended, the more restrictions are imposed on the operation of the aircraft. For example, flights are limited by weather conditions or transferred from passenger flights to cargo transportation...

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

The navigator's place and again the loads on the floor...

Wiring 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...

Studying the insides of the plane was not without an attentive local “controller” ;)

If cracks are detected, they can now be fixed or eliminated using adhesive methods, 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, there are still a very large number of IL-76s in operation around the world, including with foreign operators, which in turn requires additional research on the resource. Therefore, these types of strength tests on 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 cabin, located several meters above the floor, the operator controls the test programs.
There are two such cabins built in the hangar...

Well, then we got acquainted with another amazing aircraft - a wooden full-size mock-up of the Il-96-300, created mainly to solve the problems of interior layout.

Even part of the wing and engine were recreated on the model...

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 included in this model...

Inside, at first glance, everything looks like a real 96. The differences become noticeable only upon closer examination. For production, in most cases, wood and plywood were used. Although, in some places, real interior trim elements are installed...

There are several salons, just like 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...

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

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

In the course of creating new types of aircraft, an increasing amount of work falls on ground testing - modern modeling techniques and test benches make it possible to obtain results with good accuracy that previously required test flights. Of course, it is impossible to do without flight tests entirely - before the first flight, it is necessary to find out a certain basic set of characteristics that fundamentally confirm the airworthiness of the aircraft, after which ground and flight tests continue in parallel.

Testing new aircraft has always been a dangerous profession. Back in the 50s. In the last century, a test pilot died on average once a week all over the world. Now the tests have become at least an order of magnitude safer. This has been greatly facilitated by the development of technology, which makes it possible to carry out an increasing amount of testing on the ground.

Both the aircraft airframe and individual systems are subjected to ground tests on special stands. All strength tests of an aircraft airframe can be divided into two large groups: static, during which the level of static strength of the aircraft structure is determined, and repeated-static (resource) tests, which are aimed at determining the fatigue strength and operational survivability of the aircraft structure.

In other words, static tests determine the ability of a structure to withstand high single loads that may arise in critical situations during aircraft operation: during sudden maneuvers, gusts of wind, turbulence, system failures, etc.

Life tests determine fatigue strength - the ability of a structure to withstand repeated loads without the formation of cracks, as well as operational survivability - the ability of a structure to resist the development of cracks and other defects that can lead to its destruction.

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Recently I was able to visit a closed workshop to conduct static strength tests of aircraft. Such tests are necessary to ensure that the aircraft does not suddenly fall apart in the air due to loads. After visiting this workshop, I realized that not all aircraft are equally strong.

Static tests are an experimental method for studying the stress-strain state and static strength of an aircraft structure. Static tests are carried out to evaluate the actual strength of an aircraft by testing the structure to failure.

The need for static tests is determined by the fact that methods for designing and calculating aircraft for strength usually use some idealized design schemes that differ from the actual design. During testing, the values and distribution of design loads acting on aircraft in various loading cases - during maneuvers, during landing, etc.

1. The place was very impressive strong first impression. I still didn’t really know what would be waiting for me there and the first thing I saw was a huge IL-76TD (long-range transport). Il-76TD (long-range transport) is a civilian modification of the Il-76MD. Military equipment has been dismantled. The vehicle's carrying capacity was 50 tons. The maximum take-off weight was 190 tons. The flight range with a maximum load was 3600 km. First flight 5/5/1982.

2. The workshop is very high. Both small and large airliners can be tested here.

3. IL-103 was hiding behind the large IL. Il-103 is a five-seat single-engine piston passenger aircraft-air taxi. The aircraft was certified according to AP-23 MAK standards in 1996. This is a relatively recent development. I would like to believe that it has successfully passed the tests, and aircraft of this model will not fall apart in the air.

4. Next to the cockpit there is all kinds of recording equipment and a large number of cables coming from the aircraft itself.

5. Supports in the workshop. Massive metal structures served as the basis for testing.

6.View from the Il-76 fuselage to the remains of the Il-96-300 fuselage.

7. These things have airplane wings on them, I think they were tested here for reliability. The wing experiences some of the heaviest loads during flight, since the plane actually hangs on them.

8. Parts of the wings are still standing on the test frames, although they are covered with a healthy layer of dust.

9. In the booth at the top of the frame, they apparently received data on the test results. This was the heart of the testing facility.

10. Racks with some equipment? The purpose of this line of cabinets remains a mystery.

11. Wing.

12. There were a huge number of representatives of the cat family in the workshop. They behaved there very freely, apparently with the departure of people they became the main ones in the workshop.

13. Small panorama.

15. Wooden aircraft for processing the ergonomics of the layout and clarifying the drawings.

17. I looked through the glass to see what was inside the booths. It feels like people are just on a lunch break, but the layer of dust throughout the entire workshop suggests that no one has been here for a couple of years.

18. Having examined the workshop, he returned to Il and climbed inside.

19. Cabin.

20. Climbed through the hatch onto the fuselage of the plane. If you look closely you can see a bunch of small cat tracks.

21. Aircraft symmetry axis.

22. Fastenings for cargo.

23. Tail.

24. Jacking trolley.

25. Once again IL-103.

28. Panoramas.

1. (clickable up to 1400)

During static and life tests of full-scale prototypes of experimental products, the calculated conclusions are confirmed experimentally. The tests confirm the correctness of the design of the structure for the given loads, and the issue of the correctness of determining the loads is resolved with the help of flight strength tests, which are carried out by specialists at the LII with the participation of specialists from the department. Today we’ll 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 strength testing complex "AK named after S.V. Ilyushin", candidate of technical sciences - Vladimir Ivanovich Tkachenko...
2.

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

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

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

Typically, the further the service life is extended, the more restrictions are imposed on the operation of the aircraft. For example, flights are limited due to weather conditions or transferred from passenger flights to cargo transportation...
11.

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

The navigator's place and again the loads on the floor...
13.

Wiring 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.

Studying the insides of the plane was not without an attentive local “controller” ;)
16.

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 cabin, located several meters above the floor, the operator controls the test programs.
There are two such cabins built in the hangar...
21.

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

Even part of the wing and engine were recreated on the model...
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 included in this model...
25.

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

And finally, another general view of the laboratory...
29.
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Aircraft static tests. Aircraft testing process

Factory tests of prototype aircraft

Preparatory work before the first flight

First flight

Testing of the leading production aircraft

Testing of production aircraft

Multi-engine aircraft testing

Preparation of test report

State tests

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