Since the Athearn NP Challenger model was released, I have been searching the landscape for the opertunity to get one for my fleet. Well it is actually a two step process. The engine I was able to purchase was a Rio Grande sound model. (Not NP) It was slightly used and missing its remote(?). The price was just too good. What made it work for me is Athearn released various Challenger tenders this last year. I was able to get an NP coal tender from MB Kline for a price that sealed the deal. So at the end of the day I will have an NP model with a Rio Grande tender.
This engine is being used in a number test activities:
1.) Test the as received Rio Grande engine, included are car length and grade limit tests as well as the standard engine & tender only tests.
This is the speed voltage function compared to the data base. The black lines are steam engine maximum, average and minimum from those limited test sample. These data base and steam engine results are all engine only on a zer grade test section. The Challenger results are shown in green and red. The green is for an engine only test with no grade. The red is run on a 2.5% grade. This cart shows the results from 4 to 16 volts on the power supply. The actua minimum sustainable speed is shown later. The challenger data runs near the average steam engine line, but is limited to voltages above 9 volts. This is likely controlled by the module that is installed on the engine. This is a determent for this engine as configured.The current voltage function data is shown following the same color code as the previous chart. The challenger data shows a current level well below the average steam engine. The current increase associated with the grade increase to 2.5% is shown with the red line.This chart shows the voltage for minimum sustained velocity. Shown as a function of engine weight. The greed circles are the actual steam engine data. The challenger data is shown as a dark blue circle. It is at 733 grams of engine weight. This voltage result is near the maximum of the steam engin data. As indicated this is a disappointing result.Here the minimum sustainable velocity is shown as a function of engine weight. The challenger data here is shown in dark blue and red. The dark blue is the zero grade result. The red is the 2.5% grade result. This level of starting velocity is disappointingly high, again near the maximum of the steam engine data.The current to weight data follow similar trends to the previous chart. The current draw level is near the steam engine average. Still higher than the modern technology would be expected to draw.This represents the torque wobble. Again the challenger result is higher than desired. The measured draw bar force is the maximum measured on the steam engine tests. This is a very positive result. It is likely due to the engine weight, which is near the maximum of any engine tested in these tests. Additionally, the rear drive wheel pair have traction tires which contributes draw bar force.This is a projection of the number of cars that can be pulled up a 2.5 percent grade. This is based on the draw bar force and a conversion from level to 2.5 percent grade. While the data on this chart is consistently defined, the force measurement and the conversion are subject to error. A recent technique has shown the train length limit for this engine is closer to 30 cars.the performance characteristic for this engine is disappointing low. This is due to the starting parameters being outside of the good ranges. This may be due to the electronics that is part of the DCC module. This is one item that should be examined further.Here the engine is actually pulling cars up a 2.5% grade. This shows the impact on velocity as cars are added. This is done at a constant 12 volt supply setting. This shows the maximum car number to be 30.This is the current draw corresponding to the data in the preceding chart. In both charts, the data symbol is for the engine only at zero grade. The red line is at the 2.5% grade. Here the current increases with grade and as the number of cars increases. The dip corresponds to the initiation of wheel slip.
2.) Because of some shortfalls in the initial tests, it is prudent to complete a maintanence on the engine and repeat the the initials tests to stablish the best mechanical baseline.
3.) The tender shells will be swapped to create the NP model. The initial test after that will be to run on DC with a minimum impact of the electronics.
4.) A second series of DC tests will be to examine the impact a Tech II PWM control on the engine performance.
5.) The next tests will be to run the model with the original electronics on a NCE DCC system.
6.) The last series of tests will be done with a Rail Pro LM-3S module
This should be fun. Check back and see the progress.
