What is the use of smoke deflectors on steam locomotives? Dose whether the locomotive is large, medum, or small have some thing to do with it? For instanse:
wheel arrangment: oo OOOO OOOO oo (big boy)
top speed: 80 mph
smoke deflector(yes/no/sometimes):no
wheel arrangment: oo OOOO oo (northern)
top speed: 120mph
smoke deflector(yes/no/sometimes): sometimes
wheel arrangment: o 000 (mongol)
top speed: (could not find top speed) probibly 40 mph
smoke deflector(yes/no/sometimes): no
Or how fast.
The purpose of smoke deflectors was to create a draft on the locomotive’s front end that would lift smoke up and out of the engineer’s line of sight, and also to keep it from drifting back into the cab itself.
The design and subsequent aerodynamics of the locomotive’s front usually had something to do with whether they were needed or not. Some 4-8-4’s like the New York Centrals “Niagara” and the Union Pacifics FEF series needed them, others like the Norfolk and Western’s “J’s” didn’t.
The locomotives usually had to have a good forward speed on them for the smoke deflectors to work.
Hope this helps.
The purpose of actual, working smoke ‘deflectors’ is to induce a large trailing vortex and relatively high-pressure air near the upper top of the boiler, to reduce the ‘vacuum’ tendency of the airflow over the boiler to pull smoke down toward the cab ventilators and windows when high-efficiency front ends no longer eject the smoke with a combination of high latent heat and effective remaining pressure at significant mass flow.
That is why the ‘ear’ type prevailed when the shovels and vanes and skyline casings that purported to ‘lift’ the smoke column at its source didn’t. And why Witte deflectors, much smaller, get the job done at least as well with considerably lower buffeting and drag, and of course superior forward visibility.
UP famously tested elephant ears on a Big Boy (which sorely needed 'smoke lifting!) and found they didn’t work well enough to continue experimenting, let alone install any for normal running. When you take this research in parallel with Kratville’s account of the experimentation that was going on with front-end performance about the same time, you get the strong impression that any engineers with reasonable knowledge of gasdynamics were full-time employed over in the diesel-Streamliner part of the company.
You will also note that the PRR T1 went to the end of its life with perhaps the worst of all the trailing smoke problems, and was never given deflectors even though, as I recall, Loewy designed some with snazzy see-through panels and big lighted numerals…
That I would luv to see! Any thoughts of applying this to 5550? Or how to handle the smoke problem into the cab ventilators?
None whatsoever, as far as I know. There was some initial discussion about installing removable Witte-style deflectors if virtual modeling indicated a gain. Mike can probably find pictures of the deflector arrangement; if not, I recall seeing at least one at the Hagley (where I was not looking for it at the time).
The most obvious ‘changes’ on 5550 are that the cab will be at least minimally air-conditioned with positive ventilation, so no reliance on ventilators that don’t, and that the fuel will be carefully graded, sized, and washed to prevent poor combustion at what may be high required firing rate for the retained 92’ grate. Those should keep the problems with wearing the smoke down; cameras are likely the ‘best’ solution for times of impaired visibility. (The instrumentation bus on the locomotive was designed to have sufficient bandwidth for multiple high-frame-rate cameras, e.g. to monitor physical wheelslip or spin as well as provide running visibility)
Or how to handle the smoke problem into the cab ventilators?
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Keep them closed. I worked on some designs for air deflection to make them ‘extractors’ using the slipstream to pull laminar flow out of the cab volume, or to create an effect like the Mercedes ‘airscarf’ around the lower-pressure area of the actual ventilation intake (which may not be on the roof at all on 5550) so that both the solids and lighter fractions in the smoke would ‘pass by’.
I suppose the only one of those options available to the Pennsy at the time was closing the ventilators. Of course the proper coal was likely provided for a while when new but that discipline went away soon enough. Nasty conditions in the cab of the T1 were legendary and I’m sure not all of it was a wild story or exaggeration.
Overmod, do you remember Juniatha’s concept drawing of a “Germanized” T1 with Witte smoke deflectors, among other things?
It might still be there in the bowels of the “Steam and Preservation” thread, if it’s there to be found.
I don’t remember what other’s thought about it, but I thought it was cool as hell! Like the PRR meets science fiction! I could have pictured Darth Vader in the engineer’s seat!
What is the 5550? T1?
It will be, if it ever gets built.
It’s the next number in sequence ‘above’ the production locomotive series, which started with 5500 so the ‘fiftieth’ locomotive was 5549.
The same convention was used to assign Tornado’s number, and I believe it’s been used for some diesel restorations.
Look up T1 Trust, read it, send in a donation, buy the Baldwin print if there’s any left.
Thanks for the informative and succinct explanation.
We have an SW1 on the property that was similarly numbered - one above the actual numbers assigned by NYC.
Picking up the number where the old one’s left off. Well, the Brits certainly set the precedent for that, but it didn’t start with “Tornado.”
Back in 1973 the Shuttleworth Collection of antique aircraft began construction of a replica WW1 Sopwith Triplane. Amazingly, Sir Thomas Sopwith was still alive (!) and involved in the project. Originally 152 were built in 1917.
“Right then,” said Sir Tommy, “We’ll call this a late production model. THIS is Number 153!”
Hey, The Man said it, who was going to argue with him?
And here it is…
It can happen in a variety of situations. South Shore’s SD38-2’s are numbered 804 and 805, right after the numbers held by the Little Joes.