There are a bunch of us on various forums that are curious about a couple of tests your magazine staff conducted on a couple of locomotives.
It seems there are a few disparities on some tests that deserve investigation. The locomotives in question are N scale and quite similar in dimensions and speed although different manufacturers.
Here are the specs and test results:
Life like FM Erie built: weight 5.7 ounces, tractive force 1.92 ounces, pulling ability est 46 cars, six wheel trucks, motor speed at top end 119mph at 12 volts.
Athearn F45/FP45: weight 6.0 ounces, tractive force 1.12 ounces, pulling ability est 27 cars, six wheel trucks, motor speed at top end
145 mph at 12 volts.
Note; both units are similar in length, both units are dc with no dcc installed. these are samples apparently submitted to MR for review. Both have blackened wheels sets. Since the weight is very close 5.7 ounces verse 6.0 ounces and the speeds are close 119 verse 145 there isn’t much of a difference there to account for the large difference in tractive force.
There is one difference between both units, but we in a concenses don’t believe this difference would cause such a disparity in pulling ability.
No traction tires on either.
That difference is on the six wheel trucks the FM unit mounting is centered where’as on the Athearn unit its offset by one axle.
Since all N scale modelers are interested in improving pulling and running ability in N scale locomotives (without traction tires)this deserves investigation.
Can you account for the disparity? and or can you retest and verify your results? and if the results mirror the original testing, can you account for the differences in pulling ability. We don’t believe that there is a considerable difference in the wheel sets since they are both blacken metal, so the friction co-effient should be similar