The MD-24F high-explosive turbojet long-range projectile in the set of the M-24 rocket system (with the BM-24 combat vehicle) was developed in accordance with the Resolution of the Council of Ministers of the USSR No.144-85ss of 04.02.56 according to the Tactical and Technical Requirements of the Main Artillery Department No.007109 of 10.02.56.
In 1954-55, Department No.2 of the Research Institute-1 initiated work to determine the possibility of creating a turbojet powder long-range attack projectile MD-24F with a range of 16 ÷ 17 km in caliber 240.6 mm on the basis of the projectile M-24-FUD.
Development of the MD-24F projectile was carried out under the contract concluded between the GAU and NII-1 No.2677 of 16.03.56, as well as under the additional agreement to the abovementioned contract No.82-I57 of II.07.58. The main contractor for the development of the projectile was NII-1, the development of the powder charge and igniter to the projectile was carried out by NII-6, the fuse to the projectile was developed at NII-22.
The MD-24F engine charge proposed by NII-6 was a sector charge of four PCI gunpowder draughts with a triangular channel, armored on the surface contacting the camera, armored vehicle number 5a. The drawback of the charge was its technological complexity. Manufacturing of shaped draughts was more difficult than cylindrical ones and their partial armor was the most difficult. During the pre-factory development it was first made manually /adhesive tape/, then in a special assembly for four projectiles, and it was also necessary to clean the armored structure manually. However, NII-6 did not find another satisfactory solution to the task that met the technical requirements. Many different designs of charges, both armoured and unarmoured, were tested. The results of the testing showed that an unarmoured charge can be used only if the combustion chamber is well insulated. With the tested samples of thermal insulation - KO-81, VHZ-4023 there were observed metal washouts of the inner surface of the chamber and strong heating from the nozzle part. There were also ruptures of the chamber during the combustion of the charge and after its completion. The best variant of thermal insulation wasn't offered by the developer, that's why they refused to use unarmed sector charges made of PCI-60 powder. During the factory development of the charge it was recommended to pay the greatest attention to the development of the manufacturing technology ensuring the quality armouring with sufficient productivity, to check the possibility of using new armouring compounds, as well as to develop the methods of armouring quality control suitable for checking the charges during the warehouse storage.
The ignition of the charge was carried out by the VA-150 ignition unit, into which two MB-2H electric fuses were mounted. The ignition system in the form of a flame retarder with electric propellants mounted in it was used in aviation rockets /ARS-57, KARS-57, etc. /, in a field rocket charge such a system was used for the first time. It has an advantage over separate location of igniter and fuse /pyropatron/, as there is no need in any afterburner, fire transfer tubes, etc. /. In the tests carried out, the ignition was trouble-free. However, the test results showed that the fire transmission from the pyropropatron to the igniter at the length of 900-950 mm caused difficulties. Due to the complexity of the design of the ignition itself, it was recommended that it should be thoroughly tested in the factory tests. According to the documentation valid at that time, the shelf life of the MB-2H electric ignition was 8.5 years, it was considered necessary to study and clarify the control of igniters and electric ignition during the storage of MD-24F shells.
On July 10, 1958 in the military unit 33491 were carried out heap tests of experimental turbojet long-range missiles MD-24F design NII-1. Shots were fired from a single guide mounted on a carriage I52mm howitzer-gun ML-20.
MD-24F projectiles with RSI-12K-MD-24F-91/57M Br-35-38-I6 armored charges with an average weight of 48.35 kg and B-25M fuses were used for testing. The average weight of the collected shells was 154.2 kg. In total, 2 groups were fired at an elevation angle of 49° with the fuse set to "M".
The results of the heap and range tests are given in the table.
| Charge temperature in ºC | Number of shots | Average experimental range Hop/in m | Characteristics of dispersion | |||||
| produced by | accounts | Wednesday m | Wb in m | Wb in thousands. | WD/Hop | WB/Hop | ||
| 8 | 5х | 18180 | 146 | 228 | 12,52 | 1/124 | 1/80 | |
| 8 | 8 | 17678 | 54 | 98 | 5,55 | 1/327 | 1/180 | |
хThree shots were fired at different angles, so they were not included among the counting.
At the conclusion of the military acceptance of the I-st Department of ASTC of GAU on the technical project of the MD-24F high-explosive turbojet long-range projectile was presented the following information:
1. Experimental design work on the MD-24F long-range projectile was not carried out in full.
2. The proposed design of the MD-24F projectile with an armored powder charge can be considered acceptable for further development.
3. The projectile as a whole is technologically advanced. There are, however, significant deficiencies that need to be corrected prior to factory testing, namely:
- the engine strength has not been sufficiently tested. It is necessary to check the true safety margin in a stationary installation on a rotary test bench;
- check the heating temperatures of the chamber in terms of wall thickness;
- consider a powder ignition system to ensure trouble-free operation of the ignition, simple manufacturing and assembly technology and ease of use.
- To strengthen the holder of the ignition;
- to consider the possibility of testing the fairing as a means of preventing the usability of the projectile in combat conditions;
- to strengthen the threaded connection between the head and missile parts;
- to check the condition and quality of gunpowder charge armor by means of accelerated storage in the range of positive and negative temperatures.
4. NII-1 is necessary to check the projectile characteristics in flight (number of revolutions, engine pressure, speed and acceleration) for factory tests. In bench conditions to determine - reactive force and single pulse.
5. To check the effectiveness of the projectile's blast effect by blasting.
6. The heap obtained by firing does not satisfy TT ¹007109. Before the factory development of the projectile it is necessary to work out the question of improving the heights of firing at the maximum range. The Institute did not carry out enough works on definition and improvement of projectile pileups at intermediate ranges. In the process of factory development of the NII-1 projectile it is necessary to work out this issue.
7. During the development of the technical project there was a full possibility to carry out more complete and comprehensive experimental studies to select and justify the design of the projectile and the powder charge. However, both NII-1 and NII-6 did not use this opportunity, leaving most of the fundamental issues to be resolved at the factory testing stage.
8. It should be noted that the report on the subject presented to NII-1 has a number of inaccuracies and incorrect technical conclusions, such as: the choice of the guaranteed limit of pressure spread; the value of the unit pulse; maximum number of revolutions; measuring the reactive force; justification of the strength of the chamber; completely absent section of the aerodynamic blowing of the projectile, as well as the lack of calculation of internal ballistics for the selected charge, etc., which indicates a poor weighting of the technical report on the projectile MD-24F.
9. The Institute should submit additional missing materials before the factory tests:
- full calculation of the internal ballistics of the projectile on the selected unarmoured powder charge.
- results of aerodynamic blows carried out at the Research Institute I and SNIP (Sofrinsky Research Range).
- full substantiated calculation of projectile strength taking into account chamber heating at t=+50°C, as well as attaching to the report a true safety margin determined in bench conditions.
In the conclusion, the following was written: "The technical design of the MDF-24F long-range turbojet blast projectile into the M-24 system may be recommended for the production of the factory batch provided that the deficiencies mentioned in the conclusions of the present conclusion are eliminated by Institutes NII-I and NII-6". The document was signed by Lieutenant Colonel Gevorkyan (Kalenik, 1.9.58), Senior Military Representative of the ANTC of the GAU.
Characteristics of the MD-24F prototype projectile [3; L.56].
| Total weight in kg | 155 |
| Length in calibers | 6,9 |
| Powder charge weight (RSI-12k brand) in kg | 46,6 |
| Weight of explosive (TNT) in kg | 18,8 |
| Speed at the end of the active section (at θо = 45°) in m/s | 587 |
| Engine running time per second | 2,8 |
| Maximum range in km | 17,8 |
Main characteristics of the MD-24 F projectile [3; LL.81,82].
| Caliber | 240,6 mm |
| Weight of projectile | 154,38 kg |
| Weight of gunpowder charge without reservation | 45,8÷46,2 kg |
| Booking weight | 2,5÷3,1 kg |
| Charge length | 7.03 klb |
| Powder charge length | 900 mm |
| Single pulse at +50°С (J1) | 206 kgsek/kg |
| at -40°С | 191 kgsek/kg |
| Form factor (is) | 0,55 |
| Maximum speed at +50°С (Vmax) | 650 m/sec |
| Victorious Goal Coefficient | 214 |
| Mass characteristics: | |
| a/ Polar moment of inertia act. | 0.13526 kgmsec2 |
| pass. | 0,10693 kgmsec2 |
| b/ Equivalent moment of inertia act. | 3,16277 kgmsec2 |
| pass. | 2,55878 kgmsec2 |
| The position of the center of gravity of the act. | 72,24 sm |
| pass. | 79,08 sm |
| Burning time at +50°С | 2 sec |
| at -40°С | 3,2 sec |
| Range of flight at +50°С | 18000 m |
| at -40°С | 17000 m |
| Angle between the dynamic axis of the projectile and tangent to the trajectory | 1º17 |
Due to the lack of true measurements, the values of Vmax, is, J1 - are given tentatively / recalculation by shooting results/.
Characteristics of MD-24F projectile[1; L.105].
| Caliber, mm | 240,6 |
| Start weight, kg | 155 |
| Weight of combat unit Air Force, kg | 19,8 |
| Maximum range, km | 17 |
| Heap of fire at maximum range | |
| TD/H | 1/280 |
| W/X | 1/90 |
After the necessary work was done in 1962, the shell was adopted by order of the Minister of Defense of the USSR.
The capacity of one volley of the BM-24 combat vehicle with 12 cellular guides with the MD-24F shells was 2 times greater than that of the BMD-20 combat vehicle with 4 cellular guides and the MD-20F shell.
The material was prepared by S.V. Gurov (Tula).
- РГАЭ. Ф.298. Оп.1. Д.3058. ЛЛ.105,106.
- ЦАМО РФ. Ф.81. Оп.836698сс. Д.222. ЛЛ.134,135,137,141,150-156.
- ЦАМО РФ. Ф.81. Оп.836702с. Д.21. ЛЛ.25,56,81,82.
- Широкорад А.Б. Отечественные минометы и реактивная артиллерия. Краткий исторический очерк. – Минск (Харвест) – Москва (АСТ). 2000. – С.358.