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Godholio posted:It's not on a treadmill. DON'T
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Apr 29, 2020 21:06
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I learned a lot of new things on the last page, awesome.
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Apr 29, 2020 21:15
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Godholio posted:Well poo poo, I always assumed it was a physical connection. Same, that's fascinating and makes complete sense now that I know it.
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Apr 29, 2020 21:27
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Previa_fun posted:Every time I see this video I wonder about the tip speed of that blade. It's got to be pushing like, high caliber handgun velocity right? It sounds insane. Speaking of which: Yeah, no. Fast handgun bullets can break the sound barrier easily, but propellor tips do not break the speed of sound on purpose for a good reason. For example, the XF-84H Thunderscreech: https://en.wikipedia.org/wiki/Republic_XF-84H_Thunderscreech "The XF-84H was almost certainly the loudest aircraft ever built, earning the nickname "Thunderscreech" as well as the "Mighty Ear Banger".[16] On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away.[17] Unlike standard propellers that turn at subsonic speeds, the outer 24–30 inches (61–76 cm) of the blades on the XF-84H's propeller traveled faster than the speed of sound even at idle thrust, producing a continuous visible sonic boom that radiated laterally from the propellers for hundreds of yards."
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Apr 29, 2020 21:46
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Just for comparison's sake an airplane propeller usually turns about 1500-3000 RPM. That hedgecutter is only spinning at the equivalent of an airplane engine at idle.
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Apr 29, 2020 21:54
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Godholio posted:Well poo poo, I always assumed it was a physical connection. There absolutely are single-spool turboprops, where the power turbine and the compressor are physically on the same shaft. The TPE331 is one, the T-56 found on C-130s, C-2s, P-3s, etc is another. The NK-12 found on Tu-95s is a three-spool design.
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Apr 29, 2020 21:54
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Godholio posted:Well poo poo, I always assumed it was a physical connection. Sometimes it is. The Pratt and Whitney PT6 and PW100 families (which make up a majority of the civil turboprop market) are all free turbine designs, but there are also "single shaft" or "direct drive" engines where the prop gearbox is connected directly to the hot section of the engine. Free turbines have the advantage of requiring far less energy to start (since the starter just has to get the gas generator spooled up), generally being quieter (the propeller can rotate slower because the gas generator and power sections don't have to rotate at the same speed), and they're generally harder to break if the pilot is kind of hamfisted. Single shaft engines have the advantage of using fewer moving parts and responding faster to rapid power changes (although FADEC has reduced this difference), and they can also be more fuel efficient since there isn't the losses associated with having an extra turbine in the engine.
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Apr 29, 2020 22:10
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Godholio posted:Well poo poo, I always assumed it was a physical connection. I as well. Learn something every day.
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Apr 29, 2020 23:06
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When you start trying to get the response of a piston engine, but the power capacity of a turbine, you start getting some weird poo poo. But to address compressor stalls, many engines have variably controlled stators that can change the compression ratio and flow rate to attenuate surging and make start up easier. 
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Apr 29, 2020 23:15
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Let's not forget that in God's chosen turboshaft configuration, the power turbine driveshaft goes back through the compressor shaft and out the front: um excuse me posted:But to address compressor stalls, many engines have variably controlled stators that can change the compression ratio and flow rate to attenuate surging and make start up easier. Yep, and depending on the aircraft/engine type there might still be sudden stoppage maintenance action required for the drivetrain in response to compressor stall, even if they're not physically connected. Ambihelical Hexnut fucked around with this message at 23:27 on Apr 29, 2020 |
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Apr 29, 2020 23:22
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Beach Bum posted:I merely watch a lot of AgentJayZ For anyone that missed this or didn't know what it meant AgentJayZ is a guy with a YouTube channel that mainly wrenches on jet engines. Sometimes out of jets and sometimes out of power turbines. He's pretty chill and seems very knowledgeable. Some of the engines even have horrible mechanical failures.
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Apr 30, 2020 00:11
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As a man with a decade's experience as a professional maintainer of turbines and gear assemblies, nothing can scare m...um excuse me posted:When you start trying to get the response of a piston engine, but the power capacity of a turbine, you start getting some weird poo poo. AAAAAAAAAHHHHHHHHHHHHH!
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Apr 30, 2020 04:35
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How do the Zorya direct reversing gas turbines work? My last boss had some experience with them but not enough to explain how they actually worked.
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Apr 30, 2020 05:17
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Elviscat posted:As a man with a decade's experience as a professional maintainer of turbines and gear assemblies, nothing can scare m... I don't know about you but to me a supercharged turbocharged dual prop anti-lag jet engine sounds pretty bitchin' to me.
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Apr 30, 2020 05:24
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GnarlyCharlie4u posted:I don't know about you but to me a supercharged turbocharged dual prop anti-lag jet engine sounds pretty bitchin' to me. They were so so preoccupied with whether or not they could that they didn't stop to think if they should.
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Apr 30, 2020 05:37
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BitBasher posted:Yeah, no. Fast handgun bullets can break the sound barrier easily, but propellor tips do not break the speed of sound on purpose for a good reason. The TU-95 Bear bomber has supersonic prop tips too.
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Apr 30, 2020 11:42
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Ferremit posted:Bear bomber 
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Apr 30, 2020 11:58
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jamal posted:
loving ouch. What happened? Lift the head and let coolant in? Or the crack suddenly got big enough let enough coolant in to hydrolock it?
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Apr 30, 2020 14:02
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Is that thing's supercharger being driven by the prop/crank AND the turbocharger
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Apr 30, 2020 14:02
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Ferremit posted:The TU-95 Bear bomber has supersonic prop tips too. So does the Harvard/T-6 Texan/SNJ ww2 trainer, which is why they make a pretty distinctive noise when they fly by. Supersonic tips not common, but not unheard of. But usually only supersonic at high settings. I don't have a cite but I seem to recall the efficiency goes way down once they start going supersonic. The madness about the Thunderscreech is that the prop tips were supersonic at idle thrust.
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Apr 30, 2020 14:15
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 I bet that made a noise.
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Apr 30, 2020 14:50
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Rude Dude With Tude posted:
Considering those tyres have around 110psi of pressure in them, and theres a HUGE volume of gas at that pressure in them, Im genuinely curious to find out how far down the bore hole that plug o tyre went
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Apr 30, 2020 15:07
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Ferremit posted:Considering those tyres have around 110psi of pressure in them, and theres a HUGE volume of gas at that pressure in them, Im genuinely curious to find out how far down the bore hole that plug o tyre went At 6 inches in diameter something like 12,400 pounds of force if I did it right.
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Apr 30, 2020 18:51
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Mr-Spain posted:At 6 inches in diameter something like 12,400 pounds of force if I did it right. Area is pi*r^2. 3 inch radius and 110psi, would be 990*pi or 3110 pounds.
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Apr 30, 2020 19:03
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Speaking of being horribly disfigured, I found this when opening all my old bookmarks: https://www.flickr.com/photos/boston_public_library/sets/72157626646768526/page2/ Edit: Oh and this:  You are welcome.
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Apr 30, 2020 19:32
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Data Graham posted:Is that thing's supercharger being driven by the prop/crank AND the turbocharger The basic aim was to use the piston engine as a gas generator, similar to the combustors in a standard gas turbine. The turbine shaft was geared to the crank to add power and the exhaust of the turbine was used as thrust. It takes the concept of the power recovery turbine to a whole new level. Those were used on the Wright duplex cyclones (I think) and were exhaust gas driven turbines geared to the crank through a fluid coupling to allow extra shaft power.
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Apr 30, 2020 19:57
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I we're posting haul truck failures... this is one of my favourites. http://nastyz28.com/threads/what-happens-when-you-over-rev-a-2500hp-78-litre-caterpillar-v18-engine.233923/ 
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Apr 30, 2020 20:01
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Good god, it's like the crankshaft hosed off into an H.R. Geiger painting.
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Apr 30, 2020 20:23
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Safety Dance posted:Good god, it's like the crankshaft hosed off into an H.R. Geiger painting. This is the best description. Make it a black and white monochrome and there you go.
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Apr 30, 2020 20:27
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um excuse me posted:When you start trying to get the response of a piston engine, but the power capacity of a turbine, you start getting some weird poo poo. This is some Rube Goldberg poo poo, aircraft engines have the most extreme weird engineering of any field. Maritime? Eh gently caress it gotta get those Newton Kilometers out of it, just add more displacement. Cars? Eh just add more cylinders. Aircraft? Well you see the counter-rotating prop is powered by the piston engine, and the turbine powers the inner shaft rotating prop. Now, the APU powers the...*screaming* Rude Dude With Tude posted:
“Just put some cones around it, no one will hit it”
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May 1, 2020 02:27
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ewiley posted:“Just put some cones around it, no one will hit it” ...was almost certainly the train of thought from someone not familiar with mining trucks. 
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May 1, 2020 02:50
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I'm surprised haul trucks haven't gotten several cameras and a HUD or virtual reality headset yet. Seems like they would be an ideal application for it.
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May 1, 2020 04:39
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Seriously. Marvin Heemeyer solved this problem almost two decades ago, how has Cat not done so?
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May 1, 2020 05:01
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Seems to partially exist already Cat Detect System Knowing what's around your 793F at all times is important. The Cat Detect system is factory installed as standard equipment on 793F Mining Trucks. The full Cat Detect system, RADAR AND CAMERA, provides both audible and visual indications of detected objects. This system uses a combination of short and medium range radars which surround the machine, along with cameras on each side to allow the operator to confirm the detected object. The cameras supplement the radar alerts and are selectable by touch screen menus through an intuitive interface. And Komatsu has KomVision™ All Around Monitoring System The real poo poo is to just git rid of the operator and go autonomous but I think the mine has to be setup for that and I'm sure there's a bunch of up front costs Galler fucked around with this message at 05:20 on May 1, 2020 |
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May 1, 2020 05:15
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Godholio posted:Seriously. Marvin Heemeyer solved this problem almost two decades ago, how has Cat not done so? Probably the same reason why, when I worked for a rural civil engineering firm, and I suggested some fancy flatscreens with advertising slide shows in our lobbies...and my boss said, hell no, people will think we're pretentious and we'll lose clients.
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May 1, 2020 05:16
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Dirt Road Junglist posted:Probably the same reason why, when I worked for a rural civil engineering firm, and I suggested some fancy flatscreens with advertising slide shows in our lobbies...and my boss said, hell no, people will think we're pretentious and we'll lose clients. Just some good old boys, sometimes flattened some cars 
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May 1, 2020 05:22
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I want my rock carriers to be strapping men with sacks overs their shoulders, no tech allowed
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May 1, 2020 05:25
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Galler posted:Seems to partially exist already Rio Tinto has set up a couple of mines in the Pilbara with autonomous trucks, but yeah, the cost was stupendous to start with. The current, cheap solution to "how do we stop haul trucks from running things over" is "four meter fluoro LED-light poles on everything we don't want them to hit, continuous positive communication over the two-way and rigidly-adhered to separation protocols". Those things are all moderately effective, together they're all pretty effective, but more importantly, they're all The Right Price™.
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May 1, 2020 05:33
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Dirt Road Junglist posted:Probably the same reason why, when I worked for a rural civil engineering firm, and I suggested some fancy flatscreens with advertising slide shows in our lobbies...and my boss said, hell no, people will think we're pretentious and we'll lose clients. As opposed to the opposite approach. Attend a meeting in a conference room and there are 8 different kind of chairs some of which date back to the '70s. Yeah, that sets confidence in your clients.
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May 1, 2020 12:46
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C-Bangin' it 
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Memento posted:Rio Tinto has set up a couple of mines in the Pilbara with autonomous trucks, but yeah, the cost was stupendous to start with. The current, cheap solution to "how do we stop haul trucks from running things over" is "four meter fluoro LED-light poles on everything we don't want them to hit, continuous positive communication over the two-way and rigidly-adhered to separation protocols". Those things are all moderately effective, together they're all pretty effective, but more importantly, they're all The Right Price™. That and firing anyone who hits something more than once
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May 1, 2020 14:31
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