There was a high degree of turbulence in close proximity to the train. There is a direct relationship between the pressure exerted on the train and the turbulence surrounding the train.
At the top of the nose there are small areas of low pressure, caused by the geometry of the model, this pressure gradient results in turbulence being generated.
Wind Tunnel Results
The velocity in the wind tunnel was not high enough to warrant continuous rigorous testing as the results would not be accurate due to the difference in Reynolds number.
Plots from the data obtained from the wind tunnel test can be found to the right.
Plots of Results