As everyone knows, C&O said its 2-6+6-6 reached a momentary maximum drawbar horsepower of 7498 at 46 mph. I never noticed until seeing the other thread that, near as we can make out, they meant the engine reached 46 mph northward in Ohio with 13000+ tons. At Milepost 61 plus 1400 ft, which suggests it was on test 104, with 162 cars and 14075 tons, rather than test 106 that didn't run that far north.It turns out we have to cut Davis train resistance in half to give the engine a reasonable chance of reaching 46 mph at MP 61 plus 1400 ft; details follow.The Davis formula says at speed V (in miles/hour) on level track a 162-car, 648-axle, 14075-ton train requires 37089.5 pounds, plus (633.375 times V) pounds, plus (7.0875 times V squared) pounds of drawbar pull:At 20 mph 52592 lb25 mph 57354 lb30 mph 62470 lb etcWe'll assume the engine's drawbar-pull-vs-speed curve is a sequence of straight lines connecting the points below:At 20 mph 95000 lb25 mph 8600030 mph 7700035 mph 6900040 mph 6200045 mph 5600050 mph 51000From MP 42.2 to MP 54.9 a northward train gains 89 feet of elevation; average compensated grade is +0.15%. The last three miles of that averages +0.18% compensated. Then 3.8 miles averaging level compensated, then 1-1/4 miles averaging 0.38% down, then 1.3 miles averaging 0.2% up.
We'll say the engine and tender weigh 500 tons. We'll say it takes 93 lb/ton to accelerate the train at 1 mph/second, a lower-than-usual allowance for rotational inertia.Total resistance on +0.15% at 20 mph is 96000 lb, so we'll say the engine passes MP 54.9 at 20 mph. (We could take the length of the train into account, but I'm too lazy to do that, so from here on the train is a point mass, and it starts accelerating as soon as the engine passes MP 54.9.) After 3.8 miles of level it's up to 30.1 mph and it passes MP 61 + 1400 ft at 34.6 mph.Halve each of the Davis coefficients and leave everything else the same-- then we'll figure the engine passes MP 54.9 at 31 mph. Speed at MP 61 +1400 ft then comes out 46.2 mph.
I don't have access to the test report or the grade profile chart for the C&O Northern Subdivision, but I assumed there was a favorable downhill grade somewhere before MP61 that allowed the test train to carry 45-50mph mph into the grade where the 7498 measurement was made. By my calculations, the Davis resistance formulas would have to overpredict by well over 20,000lbs for a single H-8 to be able to haul a train that heavy at 46mph on level track (even if the loco was making 7500hp). If the Davis prediction is reasonably accurate, I don't know how the train could even reach that high of a speed without a suitable downhill stretch prior to MP61 or a second locomotive in the consist (a la NYC practice). I calculated that a 14075 ton train would have to be on a 0.09% downgrade to produce approximately 61,000 lbs resistance at 46mph which corresponds to ~7500 DBHP uncorrected for engine weight. As far as I know, there is no mention of a second locomotive in the test train (although IIRC Huddleston talks of other testing in the mountains to establish coal train tonnage ratings where a second engine was in the consist but not doing much work).
The biggest takeaway for me is that rolling terrain makes it darn near impossible to reliably determine DBHP or DB pull curves. There are just too many dynamic effects to measure power with any degree of precision. Add to that the inherent characteristic of reciprocating steam locomotion to produce a peaky, parabolic power curve and the task of accurate measurement on the road becomes all that much more difficult. Of course, railroads had very little use for knowing peak horsepower of their locomotives (other than possibly to evaluate equipment modification effectiveness on an apples to apples basis). At the end of the day, I think the railroads cared about such things as gross ton-miles per hour over the run and efficiency in terms of fuel and water consumption per ton-mile.
sgriggsrolling terrain makes it darn near impossible to reliably determine DBHP or DB pull curves.
You seem to imagine when the train runs from +0.2% onto -0.4% the dynamometer car's drawbar pull reading is thrown way off-- too many "dynamic effects". What effects?
First of all, Merry Christmas!
By dynamic effects, I am referring to changing train resistance because of changes in grade from downhill to uphill. These changes in train resistance cause changes in the balancing speed. If the speed is not constant, the DBHP calculation (speed x pull/375) will not yield a reliable sustained HP value.
Let me explain further. On p 156 of The Allegheny Lima's Finest, Huddleston and Dixon give the following description of the line profile near MP 61:
"Test run No. 104, of August 6 (1943) with 14,075 tons, established an all-time drawbar horsepower record: 'The highest instantaneous drawbar horsepower occurred ... at mile post 61 plus 1400 feet (about ten miles south, or east, of Circleville, Ohio), at which time a maximum of 7,498 drawbar horsepower was developed at a speed of 46 miles per hour.' The profile of the line between mile post 58 and 62 reveals that the train would have built up considerable momentum past mile post 61, along trackage with 'roller coaster' contours: upgrade (.20%) from mile post 58 to 59, then downgrade for a mile and a quarter (mostly .42% with some .21%), then upgrade again for a mile and a quarter (.20% with some .16%). At the point where the highest instantaneous drawbar horsepower was recorded, all of 1608's train would have been out of the dip and on the upgrade."
Note that the authors describe this section of the line as having "roller coaster" contours. Keep in mind also that the train does not in reality behave as a point mass, but each car is affected by the grade on which it is running. Assuming the coupled length of each car is 45 feet, a 160 car train would be 7200 feet long (about 1 1/3 mile in length). Therefore, as the train transitions from negative grade to positive grade, the resistance would be constantly changing as more cars went from a negative effect on the aggregate resistance to a positive effect. Straightforward physics (not Davis approximation) shows that a 14,075 ton train exerts 28,150 lbs of grade resistance for every 0.1% of grade. Going from the -.42% grade around MP 60 to a +.20% grade around MP 61 means the grade resistance alone would swing from -118,230lbs to +56,300lbs in a track distance of less than 2 miles! That doesn't even take into account the locomotive weight (a not insignificant 500+ tons), which similarly shifts its effect on measured DB pull from positive to negative. The transition from -.42% grade to +.20% grade would also mean a slowing train as more cars move onto the positive grade. A DB horsepower calculation from a slowing train is not an indication of sustainable horsepower.
It was these dynamic effects on train resistance that lead me to question the meaningfulness of DB horsepower calculations on such a grade profile.
sgriggsA DB horsepower calculation from a slowing train is not an indication of sustainable horsepower.
In reality, if the train is accelerating, and the dynamometer car shows 90000 lb drawbar pull at 20 mph and then 80000 lb at 25 mph and 70000 lb at 30 mph, that's useful info-- especially if we do it over again. We'll need to correct for gravity's pull on the engine, and the engine's acceleration, but that's easy if we're watching speed and grade closely.
Behind the dynamometer car-- what do we care what's going on back there? If the engine's drawbar pull is 90000 lb, then it's 90000 lb, whether the rest of the train is going uphill or down, or accelerating or slowing.
"Dynamic effects on train resistance"-- if the conductor on the caboose throws out the anchor, how would that invalidate the drawbar pull reading? The train will slow, the engine will continue to pull, the dynamometer will continue to record drawbar pull and speed correctly... what's the problem?
"We'll need to correct for gravity's pull on the engine, and the engine's acceleration, but that's easy if we're watching speed and grade closely.
Behind the dynamometer car-- what do we care what's going on back there? If the engine's drawbar pull is 90000 lb, then it's 90000 lb, . . ."
You, sir, get an A in Engineering Mechanics along with a call to teach the class next semester.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Just curious - Does the dynamometer car have some type of level to record the instantaneous grade or do they rely on known grade profiles of the test route?
Thanks
Anthony V.
Good point-- they couldn't measure grade since they can't separate it from acceleration, but maybe they could get the combined grade-acceleration correction for the drawbar pull?
Your guess as good as mine, and my guess is no such device. They measured speed and calculated accel from that, and got grade from the track charts, which couldn't be perfectly accurate.
Paul Milenkovic"Behind the dynamometer car-- what do we care what's going on back there? If the engine's drawbar pull is 90000 lb, then it's 90000 lb, . . ." You, sir, get an A in Engineering Mechanics along with a call to teach the class next semester.
If that gets an A, then can I teach the phlogiston theory in your school's thermodynamics course for one?
Of course it matters what the train is doing back there. The dynamometer isn't measuring the locomotive's drawbar pull, it's measuring the strain between the tender drawbar and the dynamometer car, probably either electrically or with hydraulics. Now if you get run-in from the train, the effective "drawbar pull" the device is measuring has little to do with what the locomotive is delivering at that moment; likewise, if slack runs out you're going to see a very high reading on the dial and graphs, again nonrepresentative of what the engine is producing.
Meanwhile, when the load on the locomotive is reduced, its power is being used to accelerate only its own mass, so it can reach a higher speed than it would if actually pulling the train. Train resistance will pull that speed down again... but the force measured as the train pulls on the drawbar will create a false impression if you ASSume it's all being generated by the steam rather than yanking the locomotive to a lower speed.
Meanwhile, if my drawbar TE curve has nonlinearities in it (due to shock, slack action, etc.) and I then use a planimeter to integrate under it for relatively short time periods, might I expect to see some resulting figures that... might not exactly reflect the reality of the dbhp actually developed by the locomotive?
Overmodif you get run-in from the train...
Overmodif slack runs out...
Overmodwhen the load on the locomotive is reduced [due to slack run-in], its power is being used to accelerate only its own mass, so it can reach a higher speed than it would if actually pulling the train.
timz Good point-- they couldn't measure grade since they can't separate it from acceleration, but maybe they could get the combined grade-acceleration correction for the drawbar pull? Your guess as good as mine, and my guess is no such device. They measured speed and calculated accel from that, and got grade from the track charts, which couldn't be perfectly accurate.
Good point Tim. I wasn't thinking about acceleration when I asked the question.
Overmod Paul Milenkovic "Behind the dynamometer car-- what do we care what's going on back there? If the engine's drawbar pull is 90000 lb, then it's 90000 lb, . . ." You, sir, get an A in Engineering Mechanics along with a call to teach the class next semester. If that gets an A, then can I teach the phlogiston theory in your school's thermodynamics course for one? Of course it matters what the train is doing back there. The dynamometer isn't measuring the locomotive's drawbar pull, it's measuring the strain between the tender drawbar and the dynamometer car, probably either electrically or with hydraulics. Now if you get run-in from the train, the effective "drawbar pull" the device is measuring has little to do with what the locomotive is delivering at that moment; likewise, if slack runs out you're going to see a very high reading on the dial and graphs, again nonrepresentative of what the engine is producing. Meanwhile, when the load on the locomotive is reduced, its power is being used to accelerate only its own mass, so it can reach a higher speed than it would if actually pulling the train. Train resistance will pull that speed down again... but the force measured as the train pulls on the drawbar will create a false impression if you ASSume it's all being generated by the steam rather than yanking the locomotive to a lower speed. Meanwhile, if my drawbar TE curve has nonlinearities in it (due to shock, slack action, etc.) and I then use a planimeter to integrate under it for relatively short time periods, might I expect to see some resulting figures that... might not exactly reflect the reality of the dbhp actually developed by the locomotive?
Paul Milenkovic "Behind the dynamometer car-- what do we care what's going on back there? If the engine's drawbar pull is 90000 lb, then it's 90000 lb, . . ." You, sir, get an A in Engineering Mechanics along with a call to teach the class next semester.
AnthonyVf I am interpreting their comments correctly, Paul and Tim are stating that the instantaneous net tractive effort and therefore traction power can be determined by applying Newton’s second law to the locomotive (and tender, if applicable) if the instantaneous locomotive acceleration and velocity, grade, and drawbar force are known. Two questions: Can this approach be used to determine the locomotive DBHP vs. velocity curve?
Two questions: Can this approach be used to determine the locomotive DBHP vs. velocity curve?
Sorta. Remember that in the '40s there weren't sensitive accelerometers, so you had to deduce it from speed data. Yes, you could insert a factor for acceleration into the calculations for horsepower.
On the other hand, people since Lomonosov have recognized the importance of steady load and steady speed in determining actual dbhp. The Russians had long continuous grades in the steppes which could be used to get horsepower at various speeds with a minimum of tinkering; the Germans and others used brake locomotives to provide reasonable train resistance without long-train effects; the British (LMS, I think) used the equivalent of dynamic braking to allow 'fine-tuning' of applied resistance. In my opinion you should NEVER measure horsepower where the locomotive, and perhaps any part of the train, is on a downgrade.
How would the behavior of the rest of the train come into play using this approach?
You'd look at the various accelerations (and changes in momenta) for different parts of the train, over the time range of interest, calculate the effect on the resistance, and incorporate into your calculations. The ringer here is that you don't know the accelerations back in the train; you only recognize the resultant when a 'node' or run-in reaches the rear coupler of the dynamometer car. The instrumentation isn't measuring that (at least, on most dynamometer cars).
Can you work over the grade profile, calculate the estimated change in each car's resistance, and sum to get a resistance figure? Yes, and I'd presume the C&O test data includes this kind of analysis. Problem is that it's theoretical and not "actual" resistance; there are other factors that could produce -- and I would argue in some very significant cases, did produce -- fluctuations in actual load that throw off the accuracy of the dbhp calculations.
OvermodCan you work over the grade profile, calculate the estimated change in each car's resistance, and sum to get a resistance figure? Yes, and I'd presume the C&O test data includes this kind of analysis.
I'm guessing they attempted no such analysis. What would they do with the result?
Overmodother factors that could produce -- and I would argue in some very significant cases, did produce -- fluctuations in actual load that throw off the accuracy of the dbhp calculations.
timzYou presume the C&O "worked over the grade profile"-- how? And calculated "the estimated change in each car's resistance"-- how?
It's tedious, but:
Look at the grade profile, and calculate an average grade for each section of the test train -- each car, if you feel so inclined. Use this as a factor in calculating car resistance (on level or upgrade) or gravitational momentum increase (after subtracting a factor for rolling and air resistance, etc. -- use relevant parts of the Ðavis formula) on sufficient downgrade. This corresponds to a particular moment, or short period, of observed test time at the dynamometer car. Lather, rinse, repeat for subsequent test-time points.
With a little additional work, you might calculate the likely slack action in the consist for a couple of seconds after the datum point for a given resistance calculation, with the assumption that grade (and resulting grade-determined factors) will not change much in that short a time, but consist dynamics certainly might.
Doing this with a computer, of course, makes the work much less tedious... once you have the model put together. I'd be surprised if some of the more-determined aficionados of train-simulation programs that have 'physics engines' in them have not already done some of this.
Regarding much of the performance of the C&O H-8.
It might be helpful to review the 1940's era dynameter car "weighing head" for measuring drawbar pull. Quoting Ralph Johnson from Baldwin Locomotive,
"...the modern railway dynamometer consists of a 'weighing head', which connects the drawbar through a properly proportioned lever to pistons operating on the hydraulic principle. These then transfer through a special diaphrams the variations due to compressive action set up by the movement of the drawbar to a movable pen on the chronograph table...The recording paper is arranged to move at a speed proportionate to the speed of the car...
...as the distance traveled is in a measurable period of time, the foot pounds of work divided by this period will indicate the horsepower developed at the drawbar...
Oil can be used in the hydraulic dynamometer system but as oil is subject to variation in viscosity due to temperature changes, it is better to use a mixture of glycerine and alcohol. Both rubber and leather are used for diaphrams. The bearings in the lever are made frictionless by the use of steel pins, carefully hardened, surounded by roller bearings. The pistions in the weighing head are supported by ball bearings with very close clearance which eliminate any loss due to frictional contact between the pistons and the cylinder bore. The piston movement on maximum drawbar pulls is only six-thousandths of an inch. The larger cylinder towards the front of the car takes the buffing shock and can register to 1,250,000 pounds with no loss of accuracy. The rear cylinder can measure any drawbar pull up to 500,000 pounds. If other limits are desired than the standard one mentioned the cylinder diameters can be changed.
...a telephone circuit connects the dynanmometer car to the engine cab so that coal, throttle, and reverse lever positions, etc. can be signaled back and recorded on the paper by magnet operated pens, and communications maintained with the cab.
Visible pressure gauges are usually placed at the front of the table so that instantaneous readings can be taked of drawbar pull, speed, train line pressures, and locomotive steam pressure.
Dynamometer cars have also been built with the chronograph table compartment raised into a cupola, thus allowing the weighing head and transmission unit to be placed underneath on the main deck of the car, out of the way...in many ways this is a very desirable plan. It allows the table operator to see much better and gives more room around the table."
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Regarding the use of the dyanamometer car, Johnson writes,
"A complete code for testing locomotives both in the laboratory and on the road has been issued by the American Society of Mechanical Engineers and adopted as a standard practice of that Society in 1926. This code with its supplementary sections on 'Definitions and Values', 'General Instructions' and 'Instruments and Apparatus' covers the subject thoroughly."
"Locomotve road tests are inherently less accurate than laboratory tests. Under the usual conditions of road service thre are bound to be wide fluctuations in speed, drawbar pull, and rate of firing, all fundamental factors in performance; and even under the most rigid control, much of this variation will inevitably remain and exercise an important influence on the results. In a locomotive, cut-off and speed, for example, vitally affect the steam consumption, and boiler performance likewise varies greatly with the rate at which the boiler is driven. Road tests should be thoroughly prepard for, conducted with care, and the results carefully analyzed, or they are likely to be misleading. The use of a dynamometer car is of great help in synchronizing the various records and makes the results much more reliable."
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Again Johnson writes concerning records,
"The number of observers required for a test depends upon the nature of the data to be obtained. When making an efficiency test at least six observers should be located on the locomotive, two for taking indicator diagrams and any other data that can be taken from the front end, two for cab data and two for coal and water records.
A suitable signal arrangement should be installed so that observations may be properly timed, and where desirable, taken simultaneously.
In the dynamometer car at least two observers are required, one to record the time of each start and stop, location points such as mile-posts, stations, bridges etc., and some to record all information on the dynamometer record and keep track of indicator cards. When testing articulated locomotves, the engine force is increased to take indicator cards for all four cylinders."
"At the end of each test a summary report should be drawn up roughly to determine if the run was of value, in order that a sufficient number of successful trips can be made to insure bringing out the desired information. Each observer can average or total his readings, and modern dynamometer cars are equipped with registering counters that enable the operator to make a calculation of the evaproration, drawbar horsepower, and coal per drawbsar horsepower within a few minutes after the run.
If possible, extra men should compute the results and make up a final report on each run, keeping as close behind the road work as possible. It is only by knowing the results of the previous runs that the man in charge of the test can intelligently plan the subsequent work...
The final report of the test will be drawn from these individual run reports."
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"Train and Weather Data - all details pertaining to the train such as length and weight, number and kind of cars, distribution of loaded or empty cars and pertinent or unusual conditions regarding lubrication, braking equipment, etc., should be recorded.
The velocity and direction of the wind may be ascertained with an anemometer. Details of the weather such as rain, snow, temperature, etc., should be noted. If an anemometer is not available the velocity of the wind may be estimated..."
"Drawbar Horsepower - This can be measured and integrated accurately by means of the dynamometer car and is the best measure of actual locomotive performance. However, as a basis for estimating locomotive performance or design it is valueless because it excludes an unknown amount of work done by the locomotive in moving its own weight, which varies widely according to the load behind the tender, the grade and acceleration."
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"RESISTANCE - When hauling a train, a locomotive develops a certain amount of horizontal pull, known as tractive force, which is equal to the resistance of the train to motion. The total tractive force which is developed in the cylinders of the locomotive, is equal to the total resistance of the locomotive, tender and train. The available tractive force, or that measured a the tender drawbar is equal to the total tractive force less that required to move the locomotive and tender and is balanced by the resistance of the train.
Resistance at any specified speed is ordinarily measured in pounds per ton, and is equal to the amount of horizontal force required to keep one ton (2000) pounds of train moving at that speed. If at any speed the locomotive is of sufficient capacity to develop a greater tractive force than required, it is capable of accelerating the train to a higher speed. A balance is reached when the maximum tractive force that the locomotive can exert at any given speed, is equal to the total resistance of the locomotive and train at that speed."
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Hope this helps give a context for much of the above discussion.
Dr. D
Overmodcalculate an average grade for each section of the test train -- each car, if you feel so inclined.
Overmodyou might calculate the likely slack action
timz Overmod calculate an average grade for each section of the test train -- each car, if you feel so inclined. No one has ever felt so inclined. To calculate the train's total grade resistance you say: this many cars, total this many tons, are on 0.2% up; that many cars, that many tons are on level; the other many cars, the other many tons are on 0.4% down. Total will be this many times four pounds minus the other many times eight pounds. Overmod you might calculate the likely slack action Guess you must mean, cars 130 to 160 are on 0.4% down at momentarily-constant 40 mph and so will be pushing on car number 129 with X pounds of force at that moment, assuming Davis resistance. How will that estimate help you evaluate anything? Not sure if this thread has been forgotten, but I’ll try to add to the debate. My take on the Q&A so far is that the dynamometer car behind 1608 may have measured a transitory 7488DHP, but this may not accurately reflect what the locomotive was actually doing- it could be an artefact caused the uncertain mechanics of a long train on undulating track. I agree with this- the dhp analysis is horribly complex and beyond present capabilities, I think. So, I suggest, we need to think about a different question, namely ‘Could 1608 have delivered 7488 DHP with this load on this track?’ I have done a number of analyses of the test runs of 1608 from Clinton Forge to Alleghany, Hinton to Alleghany, and northwards from Russell. I use computer models of engine power and efficiency, Boiler outputs and efficiency, and locomotive and train resistance to ‘drive’ the test trains over the stretches concerned. The models have been validated extensively against masses of UK test data collected in the 1950s. They predict results from Altoona collected 40 years prior to that very well. I am beginning to suspect that the laws of physics and chemistry are the same on both sides of the Atlantic. I don’t have detailed C&O gradient profiles, but for reasons you have discussed these are pretty useless when very long trains are involved. I estimate heights along the way from Google Earth, which seems better than it used to be- within a few feet of true at each point. Over a reasonable distance the estimated gradient is therefore pretty much spot on. For example, I get the westbound climb to Alleghany at exactly 1/88 over 12 miles. My objective is to see if I can reproduce the reported coal and water consumptions. I treat wagon resistance as an unknown- as Sgriggs observes, Johnson cannot be relied on; I adjust the wagon resistance to deliver the reported mean dhp. These exercises have all sorts of uncertainties in them, and if you get within 5% of the reported coal and water values you are doing very well. The simulations I have done climbing to Alleghany westward with empties and eastward with loads are sufficiently close to what is reported for me to be confident that the models are basically sound in this environment too. 1608 was flat out, if not quite on its knees in near full gear climbing the 1 in 88 at about 13mph with the empties; it really wouldn’t have been practicable to take even 200 tons more. It could have taken perhaps 500 tons more loaded coal eastbound. The test report makes clear that 6600-6900DHP was regularly sustained on some H8 test runs. At 45 mph, my model of locomotive resistance gives about 700HP. (It would be good to have independent confirmation of this, for they may be special factors in the US the model does not take into account; but there is no reliable data I am aware of). This means the cylinder power required would be around 7500. North of Robbins Ohio, the line rise very gently up the Scioto valley. The line is about 650’ above sea level there. It falls quite sharply to 600’ 5-6 miles further on, down to the riverside. After about 15 miles at near dead level, it then climbs about 100’ over the next 27 miles to Circleville. Driving 1608 in 50% cut off on this stretch with 14075 tons, it bounces along quite happily at 43-46 mph developing, as reported 6600- 6900DHP, until a relatively steep uphill stretch brings it down to about 33mph, rising back to about 46mph at the foot of the downgrade mentioned in the earlier correspondence. If left in this cut off speed would fall by a few mph on the upgrade near mp61, and with it IHP and DHP, back to the bottom end of the range around 6600. But what if cut off were advanced to 55% for 90 seconds or so climbing the grade? Well cylinder power would rise to over 8000, and dhp, albeit for a few seconds only, would hit 7500. Now I want to stress that all these DHP estimates neglect all the factors you have discussed, and my analysis is really only valid for train of less than a couple of hundred yards length. My only real conclusion is that there seems to be good evidence that an H8 can sustain 7500hp in the cylinders at this speed, and a piece of short term showmanship could easily take this above 8000, in which case 7500DHP is certainly possible. The engine model say that 7500IHP at these speeds needs about 120000lbs/hr steam to the cylinders, say 110000lbs water evaporated/hr, or about 800lbs/sqft grate/hr, 20000lb coal/hr. This is not unreasonable with this quality of coal- US draughting was able to deliver 1000lbs water/sqft grate/hr as on e.g. the Niagara and T1 tests. Boiler efficiency is falling rapidly at 800lbs/sqft/hr, so this is likely the sensible practical limit of the boiler- 700lbs/sqft/hr or just under 7000IHP would perhaps be a more realistic estimate of maximum daily capability (The feats of the T1 and Niagara at higher rates are magnificent, but no guide to their daily capabilities- the NYC thought a Niagara was worth no more than 4500IHP in service even though it achieved 6600IHP on test!) Could you up the H8 steam rate short term from 120 to 130000lbs/hr for a minute or so to deliver 8000+IHP?- almost certainly. And if you really wanted to, could you sustain this for longer, to prove a point?- well, quite possibly in my view, but thus would not be a serious measure of true daily capability, just one for the record books. Overall, I’m inclined to let 1608 rest in peace, with its laurels intact.
Overmod calculate an average grade for each section of the test train -- each car, if you feel so inclined.
No one has ever felt so inclined. To calculate the train's total grade resistance you say: this many cars, total this many tons, are on 0.2% up; that many cars, that many tons are on level; the other many cars, the other many tons are on 0.4% down. Total will be this many times four pounds minus the other many times eight pounds.
Overmod you might calculate the likely slack action
Guess you must mean, cars 130 to 160 are on 0.4% down at momentarily-constant 40 mph and so will be pushing on car number 129 with X pounds of force at that moment, assuming Davis resistance. How will that estimate help you evaluate anything?
Overall, I’m inclined to let 1608 rest in peace, with its laurels intact.
Dreyfuss,
Looks like a reasonable analysis to me, there was certainly enough hot water in the boiler of an H-8 to support an extra ~600-900DBHP over max continuous DBHP for a couple of minutes.
- Erik
Mr.
Thank you for that excellent analysis! The reputation of the H-8 and the Lords of Steam at Lima will live on!
Of all the mighty 1600's built - 60 for the Chesapeake & Ohio - and 8 for the Virginian Railroad - only two remain - one "hero" C&O 1601 - the second produced - and kept heated indoors in absolutely mint condition in the Henry Ford Museum in Dearborn Michigan. And one "beater" C&O 1604 which spent years rusting outdoors on the scrap line in Russel, KY. and was later given to the Virginia Museum of Transportation where it was in effect drowned in a flood and afterwards thankfully ended up still stored out of doors in the B&O Transportation Museum. Thankfully, these two remain of the first 4 built and unlike all the Pennsylvaina Railroad T1 engines and New York Central Railroad Niagara and Hudsons.
Of the - biggest - most mighty - strongest - gigantic - ultimate power - steam locomotives ever built are the 20 Union Pacific "Big Boy" of which 8 survive and these two mighty Cheasapeake & Ohio "Allegheny" of the 68 built. All but three "Allegheny" lived normal lives and were scrapped - except the two survivors that remain - and one drama queen C&O 1642 went up in a boiler explosion in June 1953 due to suspected low water while working at grade under power killing the crew. Apparently the boiler ended up quite a ways from the site of the explosion. One "Big Boy" drama queen UP 4005 similarly was wrecked and went down on its side in a wreck in April 1953 at 50 mph also killing the crew.
Every time I look at that firebox supported by a 6 wheel truck and contemplate the power in that boiler - I reel to that much potential bottled on wheels hurtling at 45 mph with that much loaded coal behind. It was sheer poetry in 20th century engineering and as massive a steel construction - a glory to behold.
And to think UP 4014 is likely to steam again in the next few years! And to think C&O 1601 remains existant today - in such a perfect condition - as to also so run again!
Doc
C&O 1604 is on display indoors at the B&O Museum now, or at least it was six or seven years ago when I saw it. That is, I TRIED to see it but there were kids swarming all over and in the cab like bees! Oh well, we've got to manufacture the next generation of railfans somehow!
I'll tell you, see one of those things "up close and personal" and like a Big Boy the sheer size of it will take your breath away.
I won't comment on the 46mph speculation but it's no surprise to me it could pull 14,000 tons o' stuff.
14,000 tons o' stuff = C&O 1600
Lets see that's 222 capt'n Ahab chasin Sperm Whales each 67 feet long and weighing in at 63 tons - load for a "whale" of a steam engine!
Or 1868 each of - tyrannosaurus rex - of which giant meat eat'n dinosaurs was a mere 7.5 short tons - and that's a train load of nasty passengers for the "tyrant king" of mighty railroad steam locomotion.
Or - let's see - 222 mighty Abrams M1 battle tanks superior in armament protection and electronics - at 68 short tons - thats enough battle equipment to fill a Iraqi Walmart parking lot with a whole lot of hurt from the "hurt locker" - and more than enough for the C&O 1600 weapon of freight railroad warfare!
Or - 5600 Cadillac SRX automobiles - each at 2.5 short tons - thats one big load of big buck limos for the - mile long steam locomotive the true "cadillac" of steam freight power!
Or - let's see - 3 C&O 1600's in one mighty lashup of freight tripple headin' power could haul one RMS Titanic steamship fully loaded from coal bunkers to smokestack weighing in at 46,328 tons - long, short or metric? - I can just see three mighty Allegheny 1600 draggin the RMS mail ship down the main line - truely a "titanic" feat for a brace of the true "titanic" locomotive of railroad steam power.
Or - At 57,900 short tons it would take a brace of 4 of the afore mentioned C&O 1600 freight railroad main line "battleships" of steam locomotion to haul the 16" gunned USS MISSOURI World War II battleship down the equivalent prescribed main line - Oh yah!
Lets see - C&O had 60 of these monsters - That's enough to haul the whole US fleet of 15 US Navy battlewagons - slidin down the main line - a veritable fleet at sail of mighty steam power
Or - A veritable flotilla of locomotives - to do the work of C&O railroadin across the tide bound Piedmont, Blue Ridge and Appelachia of Kentucky, Michigan, Ohio, Virginia and West Virginia of America.
14,000 tons - haul a whole lot o' stuff!
Also remember that the reputed 7498 drawbar HP produced by the H-8 is routinely duplicated by pairs of GEVO's or SD70ACe's on any number of trains every day in North America.
Dreyfusshudsonwith 14075 tons, it bounces along quite happily at 43-46 mph developing, as reported 6600- 6900DHP, until a relatively steep uphill stretch brings it down to about 33mph
Another question: did the test train stop at the coal dock at MP 34.6? If so, they couldn't reach top speed by MP 42.2, the foot of the climb.
I'm using the Dave Cramer copies of the Nov 1960 C&O charts-- more info from them below.
Yeah, sure sounds like there was a coal dock near Coal Dock Rd (39.03435N 82.91636W). But the 1960 chart says "coaling station" at MP 34.6, and if you go to historicaerials.com and search for 39.142N 82.879W and choose the 1960 aerial you'll see what I assume was this coal dock. Far as I can tell from the chart the bridge at 39.1473N 82.86545W was about MP 35.35, and this structure is about 0.75 mile south of that bridge. I'm not enough of a C&O fan to know when or if this coal dock replaced the one near Robbins.
So we'll forget about the 2-6+6-6 stopping for coal at MP 34.6.
So you think it can pass the top of the grade MP 54.9 at 33 mph. (Chart shows the top of the grade at the midpoint of the curve, maybe 400 ft north of the bridge over the N&W main at 39.37116N 82.97439W.) Which means you think the train's resistance is less than half of Davis-formula resistance. If resistance were that low, you could place the train on a long 0.2% grade and it would eventually accelerate to 65 mph-- with no engine pulling it. Just gravity. Think that's true?
Or are you assuming the 2-6+6-6 is more powerful than the drawbar pulls I chose above? What is your assumed drawbar-pull-vs-speed curve, and your assumed train resistance?
The chart shows Milepost 0 at about 38.7300N 82.8829W, between the two curves. The bridge at 39.02672N 82.91614W south of Coal Dock Rd scales at MP 22.30. The bottom of the long climb, MP 42.2, is about 39.2288N 82.8529W, midway between the two slight curves to the right. Elevation there is 603.1 ft; elevation at the summit at MP 54.9 is 691.9. Total curvature in the 12.7 miles is about 322 degrees, so the average compensated grade is 0.15%.
Then at MP 58.71 elevation is 688.4; the curvature in that 3.8 miles is enough to make the compensated grade zero. The bridge at 39.44077N 82.9750W is MP 59.7; the overpass at 39.45915N 82.97124W is mp 61.0. The track then curves left to the undergrade bridge at 39.4649N 82.9709W, MP 61.43, elevation 678.5.
Thanks tmz.
On the coal dock, I've now been sent the track plans, and firstly it is clear that MP 0 is where the tracks diverge, not at the switches, so my MP distances are ca 0.5 miles out, and secondly there was indeed a big coal dock at Mp 34.6! This is about 1.3 miles i.e. ca. 1 train length north of the road bridge, and looking at Google Earth carefully, you can see there is just about room for two tracks to the west of the now single track main.
As to the coal dock at Robbins, the line was built from Limeville to Waverly in 1917 to connect with the N&W there, at ca. mp 29. The C&O then built its own line north to Columbus from that point 10 years later. Since there will have been a need for a coal dock in 1917, maybe Robbins was the original one? But why would the C&O build a new one with the end of steam near? This link above gives some detail on Waverly, mostly N&W, and shows the same photo I posted, siting the dock at Gravel Washer Road near Waverly, but this is several miles from the tracks. http://www.waverlyinfo.net/n---w---c---o-in-pike-co.-ohio.html Someone out there must know the detail, but it doesn't add too much to the overall discussion, I think.
On rolling resistance, gravity is pretty potent stuff. Over here, there is about 10 miles of 1.25% going north from London to Glasgow in the Scottish lowlands, pretty straight. In 1961, the late running Midday train to London cleared the southbound summit at 60 mph, and the driver shut off steam and evidently ‘forgot’ to apply the brakes, with the result that the bottom of the bank 10 miles further on was passed at 105mph. (Well documented; The speed limit was 75mph at the time). 10 more miles of the same would have taken them well past the world speed record for steam; the easy way to beat this is find a long stretch of steep downhill and let gravity do the work. My equations suggest that the 14000 ton train would take 30 miles to accelerate from 40 to 54 mph without steam on 0.2%. My guess is the balancing speed would be in the high 50s, not sure about your 65mph. With 30 miles of 0.3% the equations say you would be up to 75 mph, of 0.4% to 93mph. Money to be made selling brake blocks to the C&O for trains heading east from Alleghany!
As I wrote earlier, the resistance equation I use gives a rolling resistance requiring 3500DHP to maintain 35 mph on the level; it requires 5200DHP at 45 mph. I haven’t checked Davis’s estimate, but if as you say he requires double this, then that says that you would need 7000DHP at 35 mph, and 10400DHP at 45 mph, the latter way beyond H8 capability, the former requiring 7500 IHP which is right at the limit of what an H8 could achieve, nothing left for any acceleration. This is just not credible, given what the H8s achieved. I would bet, though haven’t checked that you simply could not lift the loads up to Alleghany eastbound at this resistance. I feel we are missing each other on this point.
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