That's interesting; never heard of that testing on the B&A before, so thank you very much, LCJ!! I did know about the tests with PRR GP-9B units carrying a device which measured drawbar strain to determine power output, for use in controlling midtrain helpers, and the PRR tests of early Locotrol, but haven't heard of this one. A quick check of what references I have here shows nothing either -- but I bet someone else here will have heard of this.
I should have mentioned something else, in conjunction with the SSBV stuff, which was commented on at another RF&OOA meeting. It was noted that some roads had experienced traction motor pinion slippage with early GE units, and that the L&N had requested that GE develop a fix. The GE man stated that he'd "never seen one slip that had been properly applied," but added that, at the request of L&N, a Pinion Slip Alarm had been developed which was then optionally available at extra cost to any buyer. (This was, I believe, right after introduction of the U30, so the reference likely is to U25 / U28 units on the L&N.)
One has to wonder whether or not action of the slip suppression equipment may have led to this pinion slippage. I do know that the PRR and the C&O complained about the performance, adhesion-wise, of the U25B in mountainous terrain with heavy tonnage, and that burning of the rail (and wheels) was an issue. Perhaps those that did not have the SSBV experienced this phenomenon, and those that did have it might have experienced pinion slippage. Not to say that all who had one, had a set of faults, and that those who had the other, had another set, wholesale; maybe just a rough correlation. (That's why I ask if you knew, specifically, of any other units that had it, to try to further this correlation between either uncontrolled spin at low speed, or else pinion slippage, as major complaints with the U25B and U28B.)
You know -- I wonder..... A few of the PRR U25C units were actually developmental U28 units, uprated to 2800 HP and using the GT-598 instead of GT-586 generator. That one you encountered with the SSBV equipment -- you don't suppose it was one of these, do you? Yes, I know, probably way too many questions......
Getting back to the test of U25B units with radio control; certainly not the best choice, in hindsight! No wonder the operation of manned helpers on the rear end continued. Fascinating, too, are your comments about the low speed performance of the U25. According to the manuals here, and the correlation in real words in the RF&OOA minutes, GE knew something about this too -- they certainly must have received complaints. This is apparently why they set up the new, transistorized control system for the (then new) U30 the way they did, and further exacerbated handling problems with the U33 with the power matching. This is what led to the performance described a year or two ago on these forums by another engineer, who noted that the ammeter on U33B units would actually DROP with an advance in throttle position, then rise up higher than predicted. Later introduction of the "two slope pressure bias fuel and load control device" further slowed loading.
Great reading, LCJ -- let me just say that we who love trains, and are engineers (but not locomotive engineers) really dig these first hand accounts to correlate the rivet counting we perform as a hobby to real world experience.