BaltACDStill appears to be very little rudder for whole lot of ship. Forward or otherwise.
You don't need that much for hydrodynamics. But yes, one of the reported things about Titanic involved her low-speed authority and her 'suction' tendency toward other ships. I'd also suspect that putting the rudder 'hard over' would effectively stall it on a ship with this mass, particularly if it were already 'overloaded' or turbulent/cavitating water were washing up into the induced region of low pressure... these things aren't just plates stuck at an angle to deflect water flow...
Here is the rudder on the United States for comparison:
I think it is well-known that 'most' of the steering authority on twin-screw ships is achieved with the screws and not with the rudder, however. Implicit in the 'missing the iceberg' scenario as I understood it was 'back on one engine' with the other kept partially or fully AHEAD, and speed used to give additional rudder authority (not held 'hard over', either), rather than trying to get way off the ship in an impossibly short time.
Looking forward to Leo Ames on the tech of this subject.
Wizlish BaltACD But we're not talking about 'backward motion', we're talking about steering when the ship is moving forward but propwash is making the rudder's action less effective. One specific point about the design of the turbine screw on Titanic was its sizing and placement to leave a considerable amount of the rudder 'unaffected' by its action when providing power, and this is part of the earlier discussion about the effect of the prop when the turbine lost input steam during the 'crash reverse' of the two engines. There was no 'backwards' involved at any point during Titanic's striking the iceberg...
BaltACD
But we're not talking about 'backward motion', we're talking about steering when the ship is moving forward but propwash is making the rudder's action less effective. One specific point about the design of the turbine screw on Titanic was its sizing and placement to leave a considerable amount of the rudder 'unaffected' by its action when providing power, and this is part of the earlier discussion about the effect of the prop when the turbine lost input steam during the 'crash reverse' of the two engines. There was no 'backwards' involved at any point during Titanic's striking the iceberg...
Still appears to be very little rudder for whole lot of ship. Forward or otherwise.
Never too old to have a happy childhood!
BaltACDRudders are for controlling forward motion - backward, not so much.
wanswheel
Rudders are for controling forward motion - backward, not so much.
M636CI believe the Titanic exhaust turbine may have played a role in the collision with the iceberg. As indcated in the video, the turbine did not reverse and was stopped during manouvering. When the Titanic went astern on sighting the iceberg, the turbine stopped. This meant that there was a stopped four bladed screw immediately ahead of the rudder, upsetting the flow over the rudder and reducing its effectiveness. If the ship had just turned without going astern, it may have been able to clear the iceberg, since the rudder would have been in the thrust flow from the turbine's screw.
The screw of the Parsons turbine would almost certainly have been 'windmilling' after shutdown, and while this would have an effect on rudder integrity it shouldn't have been any more effect on rudder integrity than that of the cavitation or vortices it produced with the turbine power.
Far more likely that the turbulence of the abruptly-reversed main screws produced lower-than-expected actual counterforce, and the deceleration would give lower rudder authority. In a very real sense if the turbine had been arranged to provide power in reverse it would have created similar cavitation and turbulence directly ahead of the rudder... but this might not have been the 'bad thing' so many people assume, for a different reason.
I don't think there is much argument that if the rudder had been thrown over (and perhaps one of the two engines slowed or reversed to give differential thrust) the ship would have missed the iceberg handily. But there is some argument that if the ship had way taken off her but had actually collided with the iceberg more 'head on' (instead of grazing along the side and popping out all those rivets) she might not have sunk at all, or in any case would have lived long enough for some of the other large ships to reach her and transfer passengers. (In that calm sea it would have been almost surely possible to come alongside even if the Titanic were down by the head and taking water...)
In a sense all this is 'second guessing' and armchair hindsight. Would I have power-steered a brand new ship and injured heaven knows how many passengers (or broken the dining-room crockery) ... and had little excuse to show, because without the disaster of the ship sinking with such a massive loss of life, it's just Schettino ship handling. And it's difficult to gauge high-momentum collisions or effects ... if anyone has seen the video of the LRC that almost hit a local freight on camera, you'll see one of the train crew bail out a couple of seconds 'early' -- he looks like a fool, but he couldn't tell from the relative accelerations what the effect was going to be.
I was distracted by work and was unable to answer this in time.
The cylinder arrangement on Diamantina was the same as the Titanic, just a smaller engine, developing 2750 shaft horsepower on each of two shafts. The Frigates had no exhaust turbine, of course.
Thinking back, I was familiar with these engines because I'd been billeted on a sister ship Culgoa in Sydney in 1969. Culgoa was just an accommodation ship but clearly a couple of junior engineers were going to check out the machinery spaces at the first opportunity.
The US Navy built 100 ships to the same design as the UK and Australia (and I think with the same engine) as Patrol Frigates (PF). The class PF was revived in the late 1970s for a new class of escort, called the PF-109 which after some changes of designation became the FFG-7 class with which I am also familiar.
By coinicidence before reading further in this thread, the Navy's Principal Marine Engineer and I were discussing the Titanic with a staff engineer.
I believe the Titanic exhaust turbine may have played a role in the collision with the iceberg. As indcated in the video, the turbine did not reverse and was stopped during manouvering. When the Titanic went astern on sighting the iceberg, the turbine stopped. This meant that there was a stopped four bladed screw immediately ahead of the rudder, upsetting the flow over the rudder and reducing its effectiveness.
If the ship had just turned without going astern, it may have been able to clear the iceberg, since the rudder would have been in the thrust flow from the turbine's screw.
Of course, it is most unlikely that the deck officers on the bridge at the time would have understood much of the ship's engineering, even if they'd been on the similar "Olympic" before.
M636C
BaltACD.
That is a fantastic video of the Titanic's massive propulsion system and put together in such a clear story. And it confirmed my assumptions about how a triple expansin engine would be built. Thanks. I had seen a triple expansion Corliss water pump at the Cincinnati water works during a field trip and it was a three cylinder unit.
I also liked the way they ended the video. Clever. But so sad for the hard working crew.
Some of this was already addressed: GEs have high-pressure fuel in lines that can fracture and spray. I do not know how many turbo lube failures involve either primary or secondary breach of the lube line, but engine oil pressure would do a pretty good spray from a crack, and the pressurized engine compartment might neatly carburete the flow...
I will however sit back and listen to the railroaders with first-hand experience cover what they have observed the problems to be.
BaltACD Locomotive left a shop yesterday after having 2 power units replaced - caught fire today inside a tunnel. Great shop work - have to check those fuel line connections.
Locomotive left a shop yesterday after having 2 power units replaced - caught fire today inside a tunnel. Great shop work - have to check those fuel line connections.
My question is a general one: Over the last year or so, I have noted on a number of passing BNSF's GE locomotives, burned places slightly over halfway back on the engine housings.
These spots range from roughly a couple of feet in diameter, to several that seem to have brned the paint off a large portion of the engine hood,[ on the mostly, left sides of the engines.] I had always thought that thses might have been a result of turbo failures, since they seemed to be in the area near of the exhaust stack.
BaltACD's statement referencing the problem of an engine fuel leak, prompts me to ask:
Are these fires very frequent?
How much of a problem are they?
Are they most a problem on the GE's?
Do the engines carry any kind of crew-activated fire suppression equipment?
Thanks
Electroliner 1935 This line confused me. Which pressure had two cylinders? Were there one High, one medium, and two low pressure cylinders which is the way I envision this?
Probably. Remember this is a condenser engine so the LP inlet and exhaust pressures can be very low and still produce useful power (cf. Titanic's engines and the Parsons exhaust-steam turbine). Probably the two LP cylinders are at the outer ends of the engine and function as one 'larger' cylinder to handle the large physical volume of steam involved.
M636CThere was a bigger frigate the Diamantina which had two four cylinder triple expansion engines.
This line confused me. Which pressure had two cylinders? Were there one High, one medium, and two low presseue cylinders which is the way I envision this?
tree68 I spent time on a Navy research ship (YAG40). A Liberty ship... The first time we arrived in Samoa, there were two frigates (I think) - Aussie and New Zealand. They left for Pearl about the same time we arrived from Pearl. They expected to hit Hawaii in 2-3 days. We took something more than a week for the same trip (at 8 knots). No problem with spray on the windscreens on the bridge... The "Granny" (Granville S. Hall) was, at the time, the only triple expansion steam reciprocating ship in active service with the Navy. I saw the engine room a couple of times, but had no reason to spend any time there. She's since been scrapped.
I spent time on a Navy research ship (YAG40). A Liberty ship...
The first time we arrived in Samoa, there were two frigates (I think) - Aussie and New Zealand. They left for Pearl about the same time we arrived from Pearl.
They expected to hit Hawaii in 2-3 days. We took something more than a week for the same trip (at 8 knots). No problem with spray on the windscreens on the bridge...
The "Granny" (Granville S. Hall) was, at the time, the only triple expansion steam reciprocating ship in active service with the Navy. I saw the engine room a couple of times, but had no reason to spend any time there. She's since been scrapped.
I spent a few hours in the machinery spaces of the Castlemaine, an Ocean Minesweeper but generally known as a Corvette, particularly after it was realised that magnetic mines made steel minesweepers a bit vulnerable. It had two three cylinder triple expansion engines and two Admiralty pattern three drum boilers working at about 200 PSI. If there was a minor steam leak, you tied a rag around it and it just dripped hot water into the bilges. It was a training ship and sat alonside the wharf at the training establishment Cerberus, running one engine slow ahead and the other slow astern... It is now preserved at Williamstown near Melbourne looking quite smart.
There was a bigger frigate the Diamantina which had two four cylinder triple expansion engines. She spent most of her life on surveying and oceanographic work and is preserved at Southbank in Brisbane, in a dry dock. A few years ago in a major flood, the dock flooded but Diamantina still floated, fortunately...
The DDGs had the most advanced conventional steam plant that could fit in a small ship but they were a long way from the simplicity of the old low pressure expansion engines. And each DDG burnt more oil in a year than all of our six diesel submarines put together and the submarines went a long way, if not particularly fast...
I find YouTube especially helpful with car repairs, nothing like watching something being done to learn all the tricks the manual doesn't show. But I agree all that is useless if you can't figure out which end of the screwdriver to use.
Back to the railroad subject, even if train crews know how to fix a problem on one of our modern computerized locomotives we are not allowed to, as the Company does not consider us qualified to perform repairs. Can't even reboot the computer screens without first calling the Diesel Doc. It's for the best I suppose, one would likely be suspended or fired if the repair wasn't done exactly right.
Greetings from Alberta
-an Articulate Malcontent
Paul_D_North_Jr wrote the following post 29 minutes ago: zugmann BaltACD Personal observation - today's T&E employees appear to be being hired from the pool of mechanically declined individuals. They may know the book discription of how something works but they can't apply to book to the steel of reality. "+1"
zugmann BaltACD Personal observation - today's T&E employees appear to be being hired from the pool of mechanically declined individuals. They may know the book discription of how something works but they can't apply to book to the steel of reality.
BaltACD Personal observation - today's T&E employees appear to be being hired from the pool of mechanically declined individuals. They may know the book discription of how something works but they can't apply to book to the steel of reality.
YouTube has it's purpose - to use what YouTube teaches one, you still have to possess some elementry mechanical skills and understandings - the controls may be computerized, what is being controlled is still mechanical - fix the mechanical ails and kludge the computer controls to achieve the desired result.
M636CThey were the fastest ships the RAN ever owned and could make 35 knots with a clean hull. At 32 knots you needed to have sailors with squeegees cleaning the bridge windows outside because windscreen wipers couldn't cope with the spray in a choppy sea.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
M636C, thanks for that. We were told that in the event of a steam leak, we were to wave a broomstick around and the superheated steam would cut it like a knife. Then we were told that steam at that pressure would expand and fill the engine room instantly, killing everyone. Hard to wave a broomstick around, especially when you couldn't find one when you needed it.
erikem and WizLish - thanks for that enlightenment on the term kludge / kluge.
And Mike/ wanswheel - thanks for those cartoons. I was wondering when Rube Goldberg's creations would be mentioned . . .
- Paul North.
54light15 In the navy in the 70s, that racist term was used quite often. The engine room's budget was pretty sparse and it was difficult to get anything new, so we had a do what is now called a kludge for almost anything. Nothing like letting 19-year-olds play with 650 psi superheated steam, but it was rare for anyone to get hurt, thankfully. Wizlish, thanks for the mention of Heath Robinson, the British Rube Goldberg. Over in the U.K, his name comes up regularly. I've got several books of his drawings and they are fantastic. If anyone has ever seen those "Gentle art of making Guinness" ads, those were inspired by him.
In the navy in the 70s, that racist term was used quite often. The engine room's budget was pretty sparse and it was difficult to get anything new, so we had a do what is now called a kludge for almost anything. Nothing like letting 19-year-olds play with 650 psi superheated steam, but it was rare for anyone to get hurt, thankfully.
Wizlish, thanks for the mention of Heath Robinson, the British Rube Goldberg. Over in the U.K, his name comes up regularly. I've got several books of his drawings and they are fantastic. If anyone has ever seen those "Gentle art of making Guinness" ads, those were inspired by him.
At the Fox River Trolley Museum, we operate a 1902 C.A. & E. Railway interurban car which has the large cartridge fuses for the light, control, and heater circuits. Lights are five in series across 600 volts. Have to get them from England as they are built to be able to extinguish an arc when they fail and no linger made here. Fuses are about the diameter of a nickle and five inches long. The newer (50's) former CTA cars still have some fuses but most circuits have circuit breakers.
Safety cars, one-man streetcars,including the foot-pedel Third Avenue and Omaha types, used circuit breaders where others used fuses. However, I khow of one property where normal equipment for operators was a supply of extra fuses,starting out with two or three of each type and hoping to have at least one when checking out. Separate fuses for the compressor, the control system, lighting, and heating.
And then the meltdown or fire.
Where I grew up, the suburban electric trains had fuses to the control system clipped in place. These were about nine inches long and about an inch in diameter, with metal ends and a non conducting central section (containing the fuse itself).
These may have been standard in other industrial uses, but in railway use they sadly resembled in size and shape the cylindrical shaft of a rail spike, something that was relatively easy to pick up (quite literally).
A number of trains that had blown a fuse in the control system due to a momentary overload had the failed fuse substituted by a spike and this ran well until something before or after the fuse suffered from whatever the fuse was meant to protect from.....
In my days on the PRR, broom handle were occasionally used to override the ground fault relays to get the train over the road. Worked until a second ground occurred.
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