https://www.youtube.com/watch?v=2RusRdlE-gg
Never too old to have a happy childhood!
That video has some of the most splendid video quality I've ever seen in a YouTube video -- even before we consider the subject matter. It's well worth watching, and I think we should encourage his 'channel' with likes and subscribes.
You do know that was CGI?
BackshopYou do know that was CGI?
CGI can illustrate things that no longer exist as well as things that only exist in the mind of the creator.
BaltACD Backshop You do know that was CGI? CGI can illustrate things that no longer exist as well as things that only exist in the mind of the creator.
Backshop You do know that was CGI?
An actual render in modern CGI would be much closer to 'photorealism', both in ray-tracing lighting effects and resolution. See the 3D derived-pointcloud models that were produced for the T1 Trust about a half-decade ago, but in color...
I enjoyed the video! Authentic footage where available (and the rendition was excellent) and CGI where needed. A pretty good balance and a great end product.
I definately gave it a "Like!"
Question - On compound non-mallet engines. Are the low pressure cylinders quartered on the same phase as the high pressure cylinders?
BaltACD Question - On compound non-mallet engines. Are the low pressure cylinders quartered on the same phase as the high pressure cylinders?
Thing is that it would require 180-degree opposition on each side to get the engine to balance, and that is manifestly not true of a Vauclain compound (I presume you mean type 1, with the high-pressure and low-pressure cylinders outside, driving on a common crosshead). There are illustrations on the Web of the special piston valve and convoluted port and passage arrangement that is at the heart of this method of compounding, and although the porting and operation are complex to analyze, the system was certainly capable of developing near- if not actual world's-fastest speeds in the early 1890s.
I think the inside connections on a Cole balanced compound are quartered at something like 135 degrees relative to the (quartered) outside. Early compounds did not use the analogy to loop scavenging to lower effective HP backpressure going into the receiver, and I'd think dynamic balance would be a more important concern that equalizing MEP... especially with the actual condensation of LP steam in the receiver and then during expansion in the LP cylinders, which was often far more abysmal than manufacturers and designers seem to have realized.
The 'answer' of course can be seen first in effective steam-streamlined passages and superheating in modern compounds, and then in the 'booster valve' applied to some of the N&W Y-class engines (which of course were only circumstantially and accidentally 'in pnase' HP to LP). I still have no hard information on whether the LP reheat 'superheater' on 160 A1 was actually useful or not. In my opinion the 'best' approach is still that proposed by Chapelon, which is like a modulated version of the booster valve: high-pressure saturated or superheated steam is preferentially injected into the receiver at acceptable determined HP back-pressure excursion, so that not only the MEP but the instantaneous pressure on the LP pistons over the effective range of their stroke 'matches' what the HP cylinders are producing. That does not require that the HP and LP be co-phased at all; in fact my RSR engine design phases the front and rear soft-conjugated engines (via a detent) at 135 relative (both engines being simple 2-cylinder DA in quarter) so that there are eight controlled power impulses per revolution for the engine as a whole, which also should help eliminate objectional high-speed surge effects.
BaltACDOn compound non-mallet engines. Are the low pressure cylinders quartered on the same phase as the high pressure cylinders?
https://babel.hathitrust.org/cgi/pt?id=uva.x002211444&view=1up&seq=604&size=125
Next question: what was more common, four cylinders all driving one axle or low-pressure driving the lead axle and high-pressure the second?
Look up 'Plancher System' for a different approach to four-cylinder compounding (e.g. the early Italian cab-forward 4-6-0 design)
The de Glehn-du Bousquet design, one of the more successful compounds, had the HP drive on the main with a conventional axle and the LP on a cranked leading driver axle. Four sets of valve gear with the LP fully adjustable separate from the HP -- a reason the French called engine-drivers 'mecaniciens'.
Most of the balanced compounds (such as Cole and Vauclain type 2, the latter being the "Baldwin balance compounding' applied to the New Haven engines) had a cranked main-driver axle and all four mains bore on the same driver pair -- in other words, not divided-drive.
An interesting type that you'd think couldn't work all that well was the von Borries, which is a normal quartered 2-cylinder DA... run as a compound with HP on one side, LP on the other, and asymmetrical counterbalancing. The original PRR T1, with the 84" drivers, was made this way and there is a photograph of it at high speed with a considerable train -- the trick was that the two sides had separate cutoff so it was relatively easy to adjust running balance at a given throttle opening and HP cutoff.
I have read & reread this thread since 2018 & it still blows my mind well from what i understand , wow just wow . thank you guys so much for deep diving for us that arent as knowledgeable on this subject
just bumping this to the top to reread
I WANT TO BUILD THIS IN HO
My fantasy Steam turbine locomotive PRR V2 #6600
Tell me more about this.
Original V1 - two Westinghouse turbines, 1 impulse and several reaction stages (similar in principle to the unit on PRR 6200) each driving four axles connected by Cardan shafts (see the Krauss-Maffei Amerika-Loks for some representative detail).
Nominal 8000shp, using a slightly-modified Q2 boiler. The original design was approved for production in 1944 (when fast, efficient power for long heavy westbounds was becoming a priority) but was 'not proceeded with' because the water rate was abysmal -- you'd have needed multiple water tenders, not just the one in the design.
Subsequently the design was revamped to utilize the Bowes drive, which would have permitted 120mph+ road speed -- this is at the same time the suggestive 'design patent' by Loewy et al. for the streamlined 'passenger' body was filed. This was stillborn when all the rest of big complicated steam development was abandoned on PRR, between 1947 and 1948.
However, at the end, 'someone' in PRR publicity ghostwrote an expansion to "9000hp" (literally; the locomotive is in ghostly outline in a PRR brochure about modern steam power!) which might have been interesting to see attempted. It is possible that something like a good double Belpaire with Cunningham circulation and Snyder preheaters could produce the required mass flow... if Operation Downfall had followed the expected course.
Even with the Bowes drives, there might have been a need for Ferguson clutches between the axles, to prevent the wheel diameters needing frequent dressing to keep them commonly profiled. Note that the early work in magnetorheologics was in the late Forties and would have been highly attractive for this purpose.
You could, for fun, design a larger nose-mounted coal bunker, and adapt the FM-TV system used for the Navy's version of Aphrodite as better view of the road...
Hermann Jones1945 The S2 also hauled lots of crack trains that the S1 seldom pulled, like the Broadway and Manhattan limited. I read somewhere that people saw the S2 once appeared in Pittsburgh, the "forbidden city" of the S1. On the other hand, I have seen pics of the T1 phototypes powered the Trail Blazer. Hi Jones1945, interesting thing that for three long years, the two prototypes ran into and through Pittsburgh without any reported troubles. Only in Summer 1945, the first derailment took place im Pittsburgh. Then, just one month after delivery of the first serial T1s, 5502 derailed on December 1, 1945, and another serial T1 the very next day. Did somehow, tragically, the two prototypes have the edge over the 5500s in curves?
Jones1945 The S2 also hauled lots of crack trains that the S1 seldom pulled, like the Broadway and Manhattan limited. I read somewhere that people saw the S2 once appeared in Pittsburgh, the "forbidden city" of the S1. On the other hand, I have seen pics of the T1 phototypes powered the Trail Blazer.
Hi Jones1945,
interesting thing that for three long years, the two prototypes ran into and through Pittsburgh without any reported troubles.
Only in Summer 1945, the first derailment took place im Pittsburgh. Then, just one month after delivery of the first serial T1s, 5502 derailed on December 1, 1945, and another serial T1 the very next day.
Did somehow, tragically, the two prototypes have the edge over the 5500s in curves?
The performance of Flash and Buck seems to vary compared to the production T1's, but they certainly didn't have an advantage in lateral motion! They did run Harrisburg to Chicago for several months, but suffered repeat derailments at Federal Toward heading east. Not every time, but often enough to be confined in 1943 to the Ft. Wayne Division like the S1. They ran towards Pittsburgh a few times between then and '45, as did the S1, but would've been cut off before the tower and get turned and/or serviced at Scully Yard across the river.
Still find it humourous that the Q1 had more clearance into Pittsburgh (and more range overall) than the passenger duplexes for a year or two. It might not have been in service as much as it could've, but it was a Panhandle regular, plus runs on the Sandusky Branch. Well over 600 miles if I did my math right. Also did some math regarding its lifetime mileage and for kicks compared it to the early records of the L-4 Mohawks. The Q1's annual average is lower that of the L-4's within their first four years, but it's higher than their mileage in passenger service during that period. Quite impressive given the lower range and speeds. The design says Shop Queen, but the mileage says Large Cruiser.
Most of the early duplex designs (B&O, ATSF, PRR Q1) were built with the assumption of minimizing 'rigid' (I.e. driver) wheelbase. The Q1 is a peculiarly interesting case, as it was specifically intended as a 5/4 expansion of the M1/M1a 4-8-2, with 77" drivers so clearly intended as dual-service, not just M&E. You would not have gotten this engine through any restricted trackwork if it had the rear cylinders a la Q2 -- even necking the cylinder support. Even a "duplex" version of an ATSF 5001/5011 class would have had a shorter driver wheelbase!
The real trouble with the Q1 in my opinion is that PRR had no idea what to do with it, certainly after 'standardizing' on T1s for all the fast passenger trains, and keeping the 50mph freight restriction postwar.
Might be a wild take, but I think the best thing for the Q1 would've been to put it in passenger service at that point. Sure it lags behind the T1 in most aspects, but it has a bit more range and availability compared to the S1 and S2. Its power curve is seemingly ahead of most 4-8-4's, and doing better than a Niagara until 45 mph while suggesting it could catch up to an N&W J at 70 mph if not a little later.
I typically think the PRR could've done with a 4-4-4-6 if they wanted to make a step up from the M1, but the fact the Q1 could still generate that much power as a 4-6-4-4 with its "restrained dimensions" is still quite impressive. And to its credit, not only does its tractive effort eclipse all the 4-8-4's, it also has an ace or two above the J and the Niagaras. As well as having higher drivers than a J, and not needed tandem rods like a Niagara, the duplex layout lends the Q1 a bit better to high speeds. Firstly in safety; as much as people like to point out the duplexes propensity to slip, none of them broke large components on the running gear. The T1's broke valves often from excessive speed, but the gear itself wasn't damaged too often. Compare that to the numerous 4-6-4's and 4-8-4's that bent or threw their rods at least once. Secondly, there's a perfomance benefit.
Rather than raising the pressure and stretching the cylinder (smaller bore, longer stroke) the duplexes use shrunk cylinders; comparitively short strokes. I recall one advert of the S1 using "switcher cylinders!" Closest comparison that comes to mind are the Bulleid Merchant Navies, quite similar to the T1's in their original form (for another time haha) but in their rebuilt form retained the quite small 18x24" cylinder dimensions, as well as a free-steaming boiler tied to a Belpaire firebox. The next closest Pacific with the same pressure and wheelsize (and cylinder count) was the 30 "shared" LNER A2's. The Peppercorn iteration managed 101 mph with a Double Kylchap and 19x26" cylinders, while the earlier Thompson A2/3's (identical TE dimensions) could match the timings of the A4-hauled Coronation to the minute, so they likely could make 101 mph as well. However, 3 of the rebuilt Navies were clocked at or slighlty above 105 mph! They're probably the highest speeds recorded for 74"wheeled locos, as both the authenticated speed records (streamlined and not) and the next loco after them to break 100 mph had 80" drivers.
So back to the Q1, even with the crowded space of its cylinders and firebox, it would be a better option for running west of Pittsburgh compared to a 4-8-4 of similar power. Could've made a good pinch-hitter on trains a T1 wasn't ready for, rather than repeatedly scrambling to hustle K4's to the task and explain to management why the Blue Ribbon trains didn't have their newest investments on the head end. At least 6130 would've only had 3 years under her frame instead of...15 at the minimum
Two initial points:
The Q2 was just too big for any conceivable passenger train PRR could have run cost-effectively... and it still would have had issues above 85mph 'making up time' -- duplex drive isn't magic -- unless you rebuilt it to zero overbalance. You also have to deal with the higher water rate of the relatively large boiler at 'passenger' mass flow with excessive dead space and 69" drivers.
The better answer across the board for passenger work was to use the Q2 boiler as the V1 with Bowes drive -- even if it involved far more independent-brake shoes and foundation!
There was no need for a 4-4-4-6 on PRR to make the greatest single-unit horsepower practically necessary. The Q2 didn't have the Lima-style double Belpaire (which was the thing most 'necessitating' that six-wheel trailer on Townsend's stillborn 4-8-6) and easily made over 7600dbhp with a four-wheel trailing truck. I doubt that the added weight of Snyder preheaters and Cunningham-circulator manifolds would constitute 'too much back-end weight gain' to require the extra axle.
What you WOULD want on a double-Atlantic duplex is the general firebox size and construction Baldwin originally intended -- 102 to 104 square feet. This was very pointedly included in the May 1945 C1a design -- which let's face it would have been a lower-augment locomotive using a little-modified Niagara boiler and good optimized piston valves.
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