Update on the steamers

[dtrainBNSF1]

Hey steamfans! It's been like 3 or 4 months since I last posted. Here's my explanation:

My computer crashed. Hard. I could barely start a session before the computer would kick itself off and restart. This problem persisted until the computer wouldn't boot at all. I finally had to put the main computer off to the side and use my pad for schoolwork. Over the break I finally had a chance to reinstall my operating system, and I thought I could get back to work.

Not so. The memory on the hard drive is corrupted - almost half of my hard drive was full, and I hadn't even installed anything Needless to say with just less than 50% of my memory left on the computer I could not reinstall train simulator. So the short of it: I'm still working off my pad and my computer is still very sick (I honestly want to put a buckshot in it and save up for another one to be honest).

Good news, though. In the last few months while I've had my forced brake from Train Simulator I've been reading stuff about locomotive power calculations to figure out what tractive effort a steamer should be putting out at any speed given the locomotive's steam evaporation rate (steam generation basically) and based on the speed and the tractive effort what horsepower it should be putting out. The most instructive article I found was an article by A. I. Lipetz from Schenecrady, NY written sometime after 1934 with several formuli and moduli for power calculation. You can view it here:

cybra.lodz.pl/Content/6334/RR_56_6.pdf

So this promises some fun time for me when I finally get my main computer back on line and Train Simulator reinstalled.

In other news, over Christmas I got some DVDs from Machines of Iron featuring SP&S 700 and Marias Pass. Oldies but goldies if you get to watch them. I used to look forward to tuning into RFD TV every Sunday afternoon back in high school around 2pm because that's when they would broadcast a show they called "Trains and Locomotives", but it was almost always something from Machines of Iron. Did anyone else get to watch that?

[dtrainBNSF1]

I'm giving this new-fangled math a whirl on a hypothetical locomotive, a C&O H-8 Allegheny 2-6-6-6, with a theoretical steam evaporation of 131380.6lbs/hr, 22.5x33 cylinders, 67-inch drivers and a working boiler pressure of 260psi. These enormous locos were said to draw nearly 7500hp at the drawbar; we'll see if that happens. The formula I'm using is t.e.=(steam evaporation/wheel diameter)*(73.85-0.195n), where n=wheel rpm. To figure out horsepower, I'm using the formula hp=(t.e.*mph)/375.

What I expect to see: According to several steam experts like Rich Melvin a super power steamer starts with full tractive effort down at 0, but with somewhat low horsepower. As speed increases, the tractive effort drops while the horsepower rises. This trend continues until about 40mph or somewhere thereabouts and then horsepower begins to drop along with tractive effort. Based on the above figures here is what I got for the H-8:

10mph = 110211 lbf ; 2938.96hp*
15mph = 110211 lbf ; 4408.44hp*
20mph = 106460.4454462686lbf ; 5677.890423800992hp
25mph = 96862.798480597lbf ; 6457.519898706467hp
30mph = 87265.15151492536lbf ; 6981.212121194029hp
35mph = 77667.50454925372lbf ; 7248.967091263681hp
40mph = 68069.85758358208lbf ; 7260.784808915422hp
45mph = 58472.21061791044lbf ; 7016.665274149253hp
50mph = 48912.80128955223lbf ; 6521.706838606964hp
55mph = 39315.15432388059lbf ; 5766.222634169153hp
60mph = 29717.50735820895lbf ; 4754.801177313432hp
65mph = 20119.86039253731lbf ; 3487.4424680398hp
70mph = 10522.21342686567lbf ; 1964.146506348258hp
*Actual results of the formula yielded higher than possible results for 10-15mph

So what do we see? Starting at 10mph, we have max starting tractive effort and 2938.96hp. Jumping to 40mph, the tractive effort has dropped to about 68069lbf while horsepower has gone all the way up to 7260hp. So far the theory has held true. Immediately horsepower begins dropping off around 45mph to 7016hp, and continues to drop to 1964hp at 70mph with a tractive effort of 10522lbf. I stopped calculating there as the lbf dropped into the hundreds at 75 which is too low to propel anything, even the loco by itself probably (10522 is already less than 1% of the total tractive effort to put it in perspective).

So, to me this seems pretty legit based on the hp curve, HOWEVER there is one thing that concerns me: the last part of the tractive effort formula (73.85-.195n) proves to be the main limiting factor here, because when .195n=73.85, this part drops to 0, which is then multiplied by the quotient (evaporation/wheel diameter), which if 0 is multiplied by anything it equals 0. In perspective, for an 80-inch express locomotive like the FEF-3 or the GS-4 this translates roughly to 90mph when we know that the GS-4 was built for 110-mph service (though admittedly they never had to run at more than 75mph) and no one's really sure what the top speed of the FEF-3 is because it never reached top speed in regular service, though UP is confident that the loco can operate safely at 120mph. According to this formula no loco should be able to hit 100mph which flies in the face of locos like the Milwaukee Road's A and F7 classes, NYC's J-class Hudsons, LNER's A4s and A3s, and PRR's T1 Duplex, all of which broke the 100mph barrier, to name a few.

I'm not sure how to rationalize this. Anybody got any thoughts?

[dtrainBNSF1]

I have had one thought occur to me, and it's related to a letter I received from the C&O historical society when I asked them about the performance of the K4 "Kanawha" locomotives. I was told that due to improved lubrication among other things the K4 could travel above 70mph in service, but was rarely allowed to do so. So that got me thinking after making my last post:

In my tractive effort formula [(evap/wheel diam)(73.85-.195n)] .195n seems to be the main limiting factor. When I got this formula I was given the figure but was not told what each figure meant. I have begun to think that maybe .195n takes into account losses due to friction, as n is wheel speed in rpm, and as rpm the actual loss in friction only increases (in my mind at least). So the question is: does this formula take into account "modern" principles of lubrication, like inclusion of roller bearings, etc.? Given my results in the last post I began to think not. So I did some research into roller bearings and found that on Timken 1111, a locomotive specially built to demonstrate what would be possible with application of roller bearings. A write-up of the tests with Timken 1111 showed that friction was reduced by 12-15%. This was the only source I could find that directly compared roller bearing performance with non-bearing-equipped engines.

To try this theory, I made another theoretical test, this time with a loco I knew had full roller bearing application: C&O 614, which hauled a 20-some-odd car excursion at a maximum speed of 79mph. With the standard formula she would be producing around 5002lbf. with 1053hp at the drawbar. Not bad, but I think it would be a stretch to expect moving nearly 30 cars with 1100 passengers aboard plus the weight of the locomotive at 79 mph with 5002lbf and 1053hp to work with. I reduced .195 by 15%, which yielded a multiplier of 0.16575 (someone check my math). With 74-inch drivers yielding 358.8rpm at 79 mph, I got 18518lbf with 3901hp at the drawbar. With a reduction of 12%, the formula showed the locomotive producing 15815lbf at 3331hp at the drawbar. These figure to me seem more likely as far as tractive effort goes. What about you guys?

[dtrainBNSF1]

In case anyone is still lurking around here...

Yeah, this thread is dead officially. I'm still modding locomotives, but I won't be posting over here on this thread. Instead check out my new thread Update on the Steamers V2 to see my new stuff that I'm working on.

See you there