REPUBLIC OF CROATIA

 

CROATIAN MINE ACTION CENTRE

 

 

TESTING OF BOŽENA-4

DEMINING MACHINE

 

 

 

 

 

 

1.      Demining machine name: «BOŽENA-4»

                                                                                                       

2.      Constructor: «WAY  INDUSTRY», Slovak Republic

                                                                               

3.      Demining company:  «PIPER»d.o.o. – Požega, Croatia

                                                                                                                     

4.      Testing period: September – November 2002

                                                                                                           

5.      Testing place:  Vukovarsko-srijemska county, demining projects:

                                      “Vuka River” and “Gaboška Vučica”

                                                                                                             

6.      Mine contaminated area for testing: 33.745 m2         

                                                           

7.      Verification of mechanically treated land:

§         manual method with metal detectors and prodders  

                                                                 

8.      Mines intended to be used in the testing:

 

§         PMA-1A    .     .     .     5 items

§         PMA-2    .     .      .    .  5 items

§         PMA-3    .      .     .     . 5 items

§         PMR-2A    .      .       .   2 items

§         PROM-1    .     .      .     2 items

§         TMM-1    .      .      .      1 item

TOTAL    .    .     20 items

                                                                                                       

9.      Mines used in the testing:  - all of the above

                                                                                                

10.  Demining machine characteristics:                                                                              

§         demining machine type   .   .    .    .     . light machine

§         working tool    .   .     .     .     .     .    .               flail

§         operation method    .   .   .    .   .                        remote controls

§         engine power   .   .    .     .      .      .      .     .      106 KS (78 kW)

§         machine weight   .    .    .    .     .     .       .      .   4.60 metric tons

§         fuel tank capacity  .   .    .   .                  105 litres

§         average fuel consumption   .    .     .     .             around 13.50 litres/h  

§         working tool width     .    .      .     .       .            2,000 mm                                                                                                                

§         clearance depth   .   .    .     .      .                      around 20 cm                                                                                                      

 

11.  Productivity of the machine in III category soil:

 

§         Per working hour: 650-1.050 m2/h (626,41 m2/h average)

§         Per day (5 working hours) : 3.250-5.250 m2/5h (4.132,05 m2/5h average)

 

12.  Testing results

 

In the testing of Božena-4 between 24 September and 20 November 2002, on demining projects Vuka river and Gaboška Vučica in Vukovarsko – Srijemska County, the following findings were reached:            

 

1.      The engine of Božena-4 is a 78 kW (106 HP) «DEUTZ BF AL 913»  (whereas the previous Božena type machines had Yanmar engines), and it has sufficient power to drive the machine and the working tool in the soil II – V category. There were no defects on the engine during the testing.

 

2.      The engine has a cooling system on air. This has proved to be a good solution, since there was no overheating of the engine and no need for standstills and additional cooling. The engine may work for at least 5 hours without overheating.

 

3.      The hydraulic system transmits the engine power for machine movement and the flail work. The flail is driven by two side hydro-engines which have sufficient power for efficient work. There is an optimum ratio between the transmission power and flail drive, which enables very good manoeuvring capability as well as good quality clearance.

 

4.      Fuel tank capacity (105 liters) and average fuel consumption (around 13.50 liters/h) enable uninterrupted work of the machine (without refuelling) of some 7-8 hours. Such a solution is favourable, with regard to the working hours of deminers (5 working hours) and it enables a continuous work of one shift.

 

5.      Dimensions of the machine (6.052 x 1.960 x 2.200 mm) are somewhat bigger than in previous versions of Božena machines, but they are still good enough for field conditions and they allow passage between trees and work in demining.

 

6.      The hydraulic system has been well designed: two hydro-engines installed on the sides of the flail enable continuous rotation of the flail and overpowering the ground resistance (digging, breaking down of soil).

 

7.      The machine construction is based on the construction machine Prime mover B4-L 1203 RC, and the armoured coating of the engine and the machine is made of steel plate 4 mm thick. During the testing, the armoured coating of the machine has shown a good protection of vital parts, so there were cases of  fragments hitting the armour, but it was not pierced.

 

8.      The machine moves on wheels over which metal tracks are mounted. The wheels are MATADOR 10,50 X 18 with full tyres, which gives resistance when hit by fragments and enables continued work. The transmission system with the engine power enables very good mobility of the machine in all terrain categories and in wet terrain as well. This technical solution enables:

 

§         Machine velocity   .    .    .     .    .    .     0 – 9 km/h

§         Velocity during work   .   .    .    .          0,5 – 3 km/h

§         Usual velocity during work   .   0,5 – 0,8 km/h

§         Transportation velocity  .   .    .              70 – 80 km/h

§         Turning when the flail is not working  .   .   .    on the spot

§         Turning while the flail is working  .  .         in a diameter of 3.800 mm

 

9.      During the testing there were no longitudinal nor transversal slopes (no possibility to measure mobility capacity). The land was flat, with gentle slopes in several places, which did not influence the machine movement and flail work.

 

10.  The machine construction has a good balance between the front and rear end, which increases mobility and maneuverability capacity. There is a flail mounted on the front end. The engine is situated in the middle of the construction, with all supporting systems (electronics, fuel and oil tanks, etc.). The recovery wench is installed on the rear end. The recovery device is type SUPER VINCH – HUSKY, the steel rope is 50 m long, 10 mm in diameter (previous Božena machines have different technical data). The recovery winch is an important part of the machine which enables more independence to the machine in difficult working conditions.

 

11.  The working tool is a rotational flail which enables treatment of a mine contaminated land up to the depth of 20 cm in the soil III category. During the testing in III category soil the average depth of 20.41 cm was achieved. The clearance depth was measured in 227 samples, each day on different positions. The minimum depth measured was 9.00 cm, and the largest 28.59 cm. The clearance depth will depend on the soil category and the way of work by the machine operator. The clearance depth is proportional with the machine velocity and daily productivity in m2. If the velocity is increased, the clearance depth is reduced and vice versa. The clearance depth is also in correlation with the operator’s work, because he regulates the depth with his actions and operation. In the initial testing period (first four days) the clearance depth was 16.02 cm. After that the chain mounts and the flail axis were welded, which increased the clearance depth. In the testing with antipersonnel mines, due to the operators fault, the treatment was not deep enough and a PMA-1A mine placed on the depth of 10 cm remained undisturbed. Average clearance depth of 20.41 cm is achieved in III category soil. Increasing the soil category and hardness of soil, the clearance depth will be reduced. The clearance width is 2,000 mm, but one should bear in mind the need for 30 cm overlapping so that no untreated stretch of land remains between two runs of the machine.

 

12.  There are 36 striker heads on the flail axis and they enable digging and breaking down of the soil. The striker heads are mushroom shaped, and they weigh 600 grams. Between the striker heads and the flail axis there are 600 mm long chains, 10 mm thick. The chain is on the mount, welded to the flail axis. The flail axis has 150 mm in diameter. It is powered by two side hydro-engines which are well protected with armoured plate from the blast of all types of antipersonnel mines. During the testing of Božena-4 the outside striker heads (one on the left and one on the right) fell off very quickly because they hit the side mounts of the flail axis. The striker heads which fall off are usually not replaced (because they will fall off again), and only chains without striker heads remain, and this should be taken into consideration when calculating the width of overlapping of two runs of the flail. During the testing of Božena-4 in the III category soil and over 33,475 m2 the chains and striker heads did not fall of or wear down. Between the testing on two projects, the machine was working in Dalmatia in a higher category soil (higher hardness of the soil). The testing showed that the shape of striker heads is optimum and chain length satisfactory (in relation to other technical characteristics of the machine). The juncture of chains and flail axis was welded later, which enabled deeper clearance. The quality of the material of which the striker heads and chains are made achieved good results in the moment of activation of both antipersonnel and antitank mines (when the TMM-1 mine having 5.6 kg of explosive was activated, 3 striker heads and 2 chains were knocked off).

 

13.  The flail axis is made of a single piece of material of good quality and it lays on two side bearings. Antipersonnel mine blasts did not cause damage that would prevent further functioning, i.e. there was only superficial damage. In the TMM-1 antitank mine blast there was no outside damage which would be visible to the eye, and this was concluded on the date of the TMM-1 mine blast.

 

14.  The protective coating of the flail had initially been made of rubber plates fastened on the support frame. During the testing such a solution proved to be impractical, since the dirt and mud thrown to the plates caused breaking of the joint and falling of off the rubber plates. The rubber plate coating was replaced with two metal plates fasten to the support frame. Such a solution proved to be better, considering the weight of the mud thrown on the coating. Nevertheless, these two plates of the flail coating closed the space above the flail axis and in the blast of the TMM-1 mine they were penetrated, knocked off and thrown away (The energy of such a quantity of explosive has no possibility of blowing off, but it breaks the joints of the coating and frame on which they are fastened). Antipersonnel mine blasts did not penetrate the coating.

 

 

15.  Božena-4 is operated by a microprocessor, with remote controls CSB T3. The maximum transmitter range is 5,000 m (with a clear line of sight). The remote controller weights 7 kg, which makes it difficult for the operator if he operates the machine from the open field and not from a special protecting cab. If the operation is performed from the protective cab, the weight of the remote controller is not important, since it is positioned on the table. The distance between the operator and the machine will depend on working conditions: if the operator works from the protective cab, the minimum distance is around 50 m, and if he works from the open field the distance is 200 m. It is very difficult to operate the machine with precision from the distance of 200 m. The designer has envisaged a protective cab, a specially designed and equipped with everything needed (electricity, generator, air-conditioning, table, chair). It is foreseen that the cab is transported with another vehicle (because it is not self-propelled), which creates certain difficulties in a mine contaminated land. During the testing the operator’s cab was not used, but the operator was situated out in the open. In these conditions (out in the open) the operator has very difficult working conditions (the weight of the remote control device and the weight of other equipment he wears, makes the operating difficult). If the operator were situated inside a cab, there would be difficulties with following the machine (since it is not self-propelled, but must be transported on another vehicle).

 

16.  Low and medium vegetation was cut down and mixed with dirt, as well as roots of the vegetation up to 20 cm deep. These results are much better than those of previous Božena machine generations.

 

17.  The machine was tested in Vukovarsko – Srijemska county, on demining projects “Vuka River” and “Gaboška Vučica”.

 

              On the project of Vuka River 16,315 m2 of III category soil were treated, with low vegetation (grass around 1 m high) and individual bushes. The average clearance depth was 18.46 cm (minimum depth 9.00 cm and maximum depth 27.50 cm, 147 samples were measured).

 

      On the project of Gaboška Vučica 17,430 m2 of III category soil were treated with low and medium vegetation and individual bushes. The average clearance depth was 22.36 cm (minimum depth 15.00 cm and maximum depth 28.50 cm, 80 samples were measured).

 

These are the overall results of the testing of Božena-4 on both demining projects:    

       

§         Total area treated    .     .    .    .    .    .    .    33.745 m2

§         Average productivity in III category soil   .    .     .    .     826,41 m2/h

§         Average productivity per 5 working hours .    .    .     4.132,05 m2/5h

§         Average clearance depth   .   .    .     .    .     .   .      20,41 cm

 

18.  On the III category soil and with clearance depth of 20 cm Božena-4 may treat 650 – 1,050 m2 per hour, or 3,250 -  5,250 m2 in a working day (5 working hours).

 

19.  Deminers of the Carlos Gassman company from South African Republic performed the search after mechanical treatment of the ground. They used manual methods with metal detectors and prodders. The search took 415 working hours and during that time they searched 33,745 m2. They did not find any remains of mines. The average of 82.58 m2 were searched in an hour, which means that in 5 working hours 412.90 m2 were searched. Having in mind working conditions, clearance depth, average results achieved, it may be concluded that one deminer could search 350 -  500 m2 in a working day (5 hours of work).

 

20.  Antipersonnel mines and one antitank mine were placed and armed for the testing (in controlled conditions) and the following results were achieved:

 

a)      PMA-1A: - 5 mines were placed in a line in different depths (5, 10, 10, 15 and 20 cm). 4 mines were activated (on 5, 10, 15 and 20 cm) and one mine (on the depth of 10 cm) remained undisturbed. Neither the flail nor the machine were damaged in the blasts of these 4 mines (one mine contains 200 grams of TNT). In the subsequent search of the ground it was concluded that one mine (in the depth of 10 cm) remained undisturbed, and the surrounding ground was treated to the depth of some 8 cm, which means that the flail did not treat the ground to the required depth and this is the reason why the mine was not destroyed. In view of the fact that other mines (placed on the same depth or even deeper) were activated, we may conclude that the machine operator in a certain moment lifted the flail and thus missed the mine. This proves that the machine can ensure continuous depth of mine clearance and can destroying mines (by activation or breaking down), but the operator has to create conditions for that.

 

b)      PMA-2: 5 mines were placed in a line on a distance of 4 m on different depths (5, 10, 10, 15 and 20 cm). All 5 mines were destroyed, 3 of them were activated (in the depths of 5, 10 and 20 cm), and 2 mines were broken down (in the depths of 10 and 15 cm). The activated mines (containing 75 grams of explosive each) damaged and knocked off 2 striker heads. The parts of broken mines were mixed with dirt. The M17 P2 detonator on the fuse was not damaged, which means that it is necessary to perform a search of the mechanically treated land, to find the remains of the mines (especially the detonator and the fuse) and remove them from the ground. The results also show that the smallest existing mine will be destroyed either by activation or by breaking down in the depth up to 20 cm.

 

c)      PMA-3: - 5 mines were placed in a line on the distance of 4 m on different depths (5, 10, 10, 15 and 20 cm). All 5 mines were activated. Neither the flail nor the machine were damaged (each mine contained 35 grams of explosive).

 

d)      PMR-2A: One mine was placed in front of the machine some 15 m away, and the tripwire was stretched toward the machine (frontal blast). The flail pulled the trip wire and activated the mine. There was a hole in a flail coating, 5 mm in diameter, made by a mine fragment. Vital parts of the machine construction were not damaged. The other mine was placed to the side of the direction of the movement of the machine and the trip wire was stretched vertically to the direction of the movement (lateral blast). The flail pulled the trip wire and pulled the safety pin out of the fuse, but the fuse was not activated and the mine was not activated. It was determined later that the UPM-2A fuse did not perform its function because it was out of order (this could not have been determined in the examination of the mines before the testing). The following may be concluded:

§         The flail has achieved its task because the safety pin was pulled out of the fuse

§         The mine was destroyed by a direct hit of the flail, the fuse was knocked off, which eliminated the risk for deminers

Such a situation is present in the mine contaminated land, because most of the mines were laid down more than 11 years ago and many mines have been deformed, damaged and out of order due to such a long time. In situations like that PMR-2A mines are rarely activated, but the working tool of the machine should be used to destroy the mines.

 

e)      PROM-1: - One mine is prepared for trip wire activation, the flail activated the mine, there was no damage to the vital parts of the machine construction, and there were some 20 dents made by fragments, 1-2 mm deep on the flail axis. There was no penetration of the material. The other mine was placed and prepared for pressure activation. While operating the machine the operator missed the mine and it was not activated. Driving the machine backwards (toward the starting point) the flail activated the mine between the flail and the joint with the machine, bellow the right support of the flail. The following damage was made:

 

§         Rear right side of the hydro-engine coating has 5 hits by fragments 2-3 cm in diameter and around 5 mm deep with a number of superficial dents

§         The right mount of the flail coating was damaged with three dents 1-1.5 cm in diameter, some 5 mm deep.

§         The right hydraulic hose was pierced in two places, the oil was leaking and it had to be repaired as soon as possible (this was done immediately).

§         There were some 20 superficial dents, smaller and bigger, the armour was not pierced.

 

f)        TMM-1: - the flail activated the mine, and the following consequences occurred:

§         A crater was created in front of (and bellow) the flail in a funnel shape, 1.30 m deep and 1.60 m in diameter.

§         The protective coating of the flail mount (two metal plates) was knocked off 15-20 m behind the machine

§         One striker head was knocked off the flail chan

§         Two striker heads were knocked off together with the chains

§         The support (frame) of the flail coating was partly deformed

 

21.  20 mines were used in the testing with antipersonnel and antitank mines. 16 mines were activated, 2 mines were broken down and 1 mine remained undamaged and 1 mine was defective.

 

22.  The following may be concluded from the overall results of testing Božena-4 with antipersonnel mines:

 

§         15 mines were activated

§         2 mines were broken down

§         1 mine remained undamaged

§         1 mine was defective

§         the overall number of 17 mines were destroyed

§         there was no serious damage on the flail and machine which would prevent further work

§         the armour of the machine provides good quality protection of vital parts of the machine construction

§         after the mechanical treatment of a mine contaminated or mine suspected ground, a follow up search method is necessary because of the remains of the broken down parts of mines

§         the flail is capable of activating and destroying antipersonnel mines up to 20 cm deep (all three mines placed on this depth were activated)

§         if the machine is operated properly, good results in destruction of antipersonnel mines (PMA-1A placed 10 cm deep remained undamaged due to the operator) may be achieved.

§         The logistic support was efficient and good, the damage was repaired immediately.

§         The machine operator and the machine make a unique functional unity and they achieve results in their mutual relations

 

23.  The following results were achieved with the TMM-1 antitank mine:

 

§         The mine was activated

§         The flail was damaged

§         Vital parts of the machine construction were not damaged

§         The machine remained functional, the operator must be positioned in a distance over 200 m (because of the intensity of the explosion sound, shock wave and possible scattering of fragments)

 

24.  During the testing and work of the machine at a work site, there were several standstills due to minor defects which were repaired immediately and the machine was able to continue working. The junctions of chains with the flail axis were welded and the rubber flail coating was replaced by the metal one.

 

25.  The transportation of Božena-4 and moving from one location to another is performed by a tow truck. Loading/unloading of the machine takes 10-15 minutes.

 

26.  Before the works start, the machine operator examines the machine, checks all the important parts and systems, checks the fuel and oil quantity (and refills the tanks), examines the flail – whether all the parts are in place and in order (striker heads and chains) and turns the machine on for a trial period. If everything is in order, the operator starts working, with the permission of the work site leader.

 

27.  Logistic support was very well organised and prepared, with sufficient quantity and types of spare parts.

 

 

                         

13. CONCLUSION

 

On the basis of our knowledge and testing results, we have concluded the following:                       

 

1.      Božena-4 demining machine is suitable for mechanical treatment of mine contaminated land.

 

2.      It may be used in soil category II – V. The best results are achieved in flat land, category III with low and medium vegetation.

 

3.      It successfully moves in and destroys all types of low and medium vegetation as well as individual bushes. It usually goes round individual trees. It may be used in forests if it can move between trees.

 

4.      The machine is operated remotely, and the operator may be situated:

 

§         Out in the open – at least 200 m away from the machine, behind the machine

§         In the armoured cab – at least 50 m away, behind the machine

 

5.      The machine operator must not walk on the land which has been treated by the machine until deminers make the verification of the area and remove possible remains of mines and unexploded ordnance.

 

6.      In a working hour the machine has treated:

 

§         In the terrain III category the average surface area of  826,41 m2

§         Daily productivity may be either increased or reduced due to vegetation type and density and mine contamination level

 

According to the above said, daily productivity (5 working hours) of Božena-4 is as follows:

 

§         In the terrain III category, the average surface area of 4,132.05 m2

§         Daily productivity may be reduced or increased by 10-20% due to:

q       Longitudinal and transversal slopes

q       Vegetation type, height and density

q       Mine contamination level

 

7.      The clearance depth in III category terrain during testing was 20.41 cm. As the hardness of the soil increases, the clearance depth reduces. The speed of the machine is in direct correlation with the clearance depth.

 

8.      After mechanical treatment of mine contaminated land with Božena-4 demining machine, a search (verification) should be done either manually or with mine detection dogs.

Manual search is performed by deminers with metal detectors and prodders. A deminer may search 350 -  500 m2 per day (5 working hours), depending on the environment conditions (slope, vegetation, mine contamination level, false alarms, etc.).

When using mine detection dogs for verification purposes, prescribed standards, methods and organisation of work should be obeyed.

 

 

                        The existing Božena-4 machine may be used in demining and mechanical treatment of mine contaminated land in humanitarian demining operations in Croatia in accordance with this Report and its conclusions.                

 

 

 

 

 

                                                                                                                                                                                      mr.sc. Ivan Šteker

                                                                                                Testing manager