Re: CONX vs UTLX

Using the drawing's in Sloan's Century and 10, I'd say the CG's are about the same. The major difference between UTLX 13120 and CONX 44 besides length 29' OES versus 32' OES is the tank diameter 6' 5" versus 6' 1". This being the case, the CG of the UTLX car would be a fraction above the CONX. There were standards for items such as this set by the Master Car Builders and ARA Car Construction Committee, which for CG would be a maximum.

To answer another comment, Track Train Dynamics is a fairly recent development in the rail industry, say 1970's on. The advent of the 263K GRL rail car, variety of car lengths (not mostly 40 footers with a few longer cars), the potential difference in adjacent cars of weights between 40K and 263K to 512K, and difference of length of truck centers to pulling faces resulted in derailments that were unexplainable at the time. TTD research explained the cause of these showing necessary changes in train make-up and handling to prevent these derailments. For the NG, cars were basically 33' OPF, light weight of 20K and loaded weight of 70K which does not give the same physical interactions between adjacent cars and track. Even adding the few tank cars at 33K and 90K makes little difference. Some of the other phenomenon, such as truck hunting, occurs at higher speed than the NG operated, 40 to 50 MPH.

In my earlier post mentioning truck condition, I forgot to include flange wear that can result in a thin or vertical flange.