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Hellcat Mobility Trials

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" Table #5

Speed in kph

Braking distance in m

Time to brake in sec

8

0.5

0.6

16

3.4

1.4

24

7.65

2.8

32

14.4

5.7

40

30.1

9.4


When driving at 50 kph, the SPG drifts to the side when brakes are suddenly applied. When the brakes are applied gradually the SPG does not drift, but the braking distance is very long (70-80 meters).

4. Mobility data

a. Average movement speed

Table #6 shows the average movement speed of the SPG

Road conditions

Distance traveled

Average speed in kph

Movement speed

Overall speed

Cobblestone highway

172

38.4

38.4

Paved highway

116

47.6

47.6

Dirt road

430

23.8

23.8

Cross-country over snow

117

19.4

19.4

The table shows that the movement speed is equal to overall speed, which indicates that the SPG is reliable.

The highway speed is limited by poor stability of the SPG, especially when driving on a highway covered in iced-over snow. At high speeds (50-60 kph) the SPG drifts to the side.

Driving along the dirt road was mostly done in second gear. Driving in third gear is limited by insufficient drive torque provided by torque converter. 

Driving in the snow was done in first gear. In second gear, the torque drops significantly due to slipping of the torque converter. The movement speed drops to less than the speed in first gear at the same engine RPM.

b. Fuel and oil consumption

Data on fuel and oil consumption in various road conditions is summarized in table #7.

Road conditions

Engine work hours

Consumption per one hour of work in Liters

Consumption per 100 km of travel in Liters

Fuel

Oil

Fuel

Oil

Highway

9 h 45 min

78.5

1.61

203

4.17

Dirt road

17 h 45 min

80.5

2.64

357

11.3

Cross-country

5 h 50 min

130.7

3.95

708

20.2


The table shows that the fuel consumption is significantly higher than the established norms for vehicles of this class.

The increased fuel consumption is explained by the uneconomical engine and insufficient drive torque provided by the torque converter.

5. Off-road performance and obstacle negotiation

a. Driving on dirt roads and off road

The trials established that:
  1. The SPG has insufficient traction with the ground. Because of this, the vehicle is unstable on packed and icy roads. 10-12 degree slopes can only be negotiated in second gear after a running start.
  2. Driving along a dirt road with deep holes and loose soil is impossible due to insufficient torque from the torque converter.
  3. The SPG cannot cross roadside ditches covered in snow that are deeper than 0.75 meters due to insufficient torque from the torque converter.
    It is possible to drive off-road if the snow is no more than 0.5 meters deep. The SPG cannot drive through snow more than 0.5 meters deep due to insufficient torque from the torque converter.
Photo #19. Driving the SPG along a smashed forest road.



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