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A turboprop is a jet engine. The propeller moves a large mass of air, increasing efficiency ... like the current turbo fan engines! lol. Pax hate turboprops be

A turboprop is a jet engine. The propeller moves a large mass of air, increasing efficiency ... like the current turbo fan engines! lol. Pax hate turboprops because of the noise and a misconception that they're not jet engines. There's no inherent safety difference, except that there used to be regional airlines flying with inexperienced pilots like cough Colgan. https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407 https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407

falcolas 6y ago
There’s more moving parts, since each prop has to rotate on its own axis in addition to rotating in line with the aircraft. Jets are stupidly simple, but turboprops are more complex due to these requirements of the props. Turboprops also can’t go as high or fast as jets, because they need a certain amount of air density to operate. They can provide fine-controlled reverse thrust, so they have that going for them. And they’re less complicated (and lighter) than a traditional piston engine, making them a win over normal engines in mid-sized aircraft. EDIT: "Jets" in the above is a poor reference to turbofans, as pointed out by replies. Thanks for the clarification. A Turbofan still has a turbine being powered by a jet engine, similar to a turboprop, but it does not have the complexity associated with being able to change the pitch of the props.
- vvillena 6y ago
  Is there any modern airliner plane that still uses jets? IIRC all modern passenger plane engines are turbofan engines. Turboprops win at slower speed, while turbofans excel in the fast-but-still-subsonic range.
  - catalogia 6y ago
    There aren't any modern planes still using turbojets. I think the Concorde might have been the last (ceased operation in 2003.) Combat jets often have very low-bypass ratio turbofan engines though. A true turbojet has a 0 bypass-ratio; a lot of turbofan fighter jets have bypass-ratios under 1, while the engines on a 787 have a bypass-ratio of 10. https://en.wikipedia.org/wiki/Bypass_ratio#Engine_bypass_ratios https://en.wikipedia.org/wiki/Bypass_ratio#Engine_bypass_rat...
  - falcolas 6y ago
    I should clarify, when I'm saying "jet", I do mean turbofans. And turbofans still include a jet engine, but the output turns a turbine which rotates the fans.
    - catalogia 6y ago
      Turbojets, turbofans, and turboprops all use gas turbines. The "jet" in this context refers to the action of the exhaust, not the mechanism creating the exhaust (which is the gas turbine.) Turbojets and Turbofans both create jets of hot exhaust gas to produce thrust. Turbojets produce thrust exclusively with this jet of exhaust gas, while turbofans produce some [often most] of their thrust by using some of the turbine's output to turn a ducted fan. Turboprops don't produce any meaningful jet of exhaust gas, instead using the output of the gas turbine to turn a propeller. Related to turboprops are turboshaft engines, which turn a power transmission shaft instead of a propeller directly. In some cases, like the V-22 Osprey, the line between a turboprop and a turboshaft is blurred. But some clear examples of turboshaft engines are in modern helicopters and Abrams tanks. There are some kinds of jet engines that don't use turbines. Ramjets and scramjets don't use turbines, but have 'jet' in the name because they produce their thrust using a jet of hot exhaust gas. Rocket engines produce jets of hot exhaust gas, but aren't called jet engines because.. reasons. > jet: A collimated stream, spurt or flow of liquid or gas from a pressurized container, an engine, etc. (Note that this makes turboprop engines not jet engines, but turbojet and turboprop engines are both gas turbine engines.)
- krisoft 6y ago
  "Jets are stupidly simple" Haha :D I don't know where that comes from. Jet engines are fiendishly complicated. If they are so simple can you explain to me how interlaced rows of stator and rotor blades turn pressure into gas speed? That one always stumped me. Or how do I make monocrystalline blades, and how can I QA them? Or what exactly a FADEC do during startup, and how do the controlled parameters change depending on atmospheric conditions? Also I heard that the injectors and the air flow in the combustion chambers is designed such that there is an outside layer of incomplete combustion creating a colder laminar gasflow to protect the chamber wall itself. How do I go about designing that? How do I cool the bearings? How does one get the rotational energy out from the centre shaft to drive an oil pump on the side of the engine? I mean these are just the first questions which pop up in my mind when I think about jet engines. And I'm not even a jet mechanic. If you truly think that jet engines are simple, then I envy your intellect.
  - falcolas 6y ago
    I was referring to the operational complexity of the final product, not in the design or manufacturing. They have two main moving parts - the jet turbine, and the turbine connected to the fan (or prop). This is in comparison to the hundreds of moving parts your average ICE has for the drive train alone, not including the electrical system that lives alongside it to facilitate timed fuel ignition. Jet engines are used on some older oil pumps because they can run for decades with minimal maintenance.
    - LargoLasskhyfv 6y ago
      [1] https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan This Genius Invention Could Transform Jet Engines, 2015, 3m51s, Bloomberg QuickTake Originals [2] https://www.youtube.com./watch?v=8aPIEsnKb6o https://www.youtube.com./watch?v=8aPIEsnKb6o Rolls-Royce UltraFan technology, 3 shaft geared turbofan jet engine, 2018, 2m29s, MDx media [3] https://www.youtube.com./watch?v=6zD4uEdCkAk https://www.youtube.com./watch?v=6zD4uEdCkAk
    - mannykannot 6y ago
      The initial comparison was turboprops vs. turbojets, so switching the comparison to the undoubted complexities of internal combustion piston engines is beside the point. The 'jet' engines used on oil pumps etc. are actually not jet engines: they are gas turbines in which an additional turbine or turbine stage is used to extract rotational power - in other words, they are more like turboprop engines than jet engines. Nevertheless, I do disagree with the suggestion that turboprops are much less safe than turbojets, and I suspect that the author of that comment was confusing them with piston engines, which also (almost always) use propellers (increasingly, we are seeing turboprop singles replacing piston twins.) Finally, piston engines themselves have become much more reliable since the days when they were the only option.
- redis_mlc 6y ago
  > each prop has to rotate Pedant.

falcolas 6y ago

There’s more moving parts, since each prop has to rotate on its own axis in addition to rotating in line with the aircraft. Jets are stupidly simple, but turboprops are more complex due to these requirements of the props. Turboprops also can’t go as high or fast as jets, because they need a certain amount of air density to operate. They can provide fine-controlled reverse thrust, so they have that going for them. And they’re less complicated (and lighter) than a traditional piston engine, making them a win over normal engines in mid-sized aircraft. EDIT: "Jets" in the above is a poor reference to turbofans, as pointed out by replies. Thanks for the clarification. A Turbofan still has a turbine being powered by a jet engine, similar to a turboprop, but it does not have the complexity associated with being able to change the pitch of the props.

vvillena 6y ago
Is there any modern airliner plane that still uses jets? IIRC all modern passenger plane engines are turbofan engines. Turboprops win at slower speed, while turbofans excel in the fast-but-still-subsonic range.
- catalogia 6y ago
  There aren't any modern planes still using turbojets. I think the Concorde might have been the last (ceased operation in 2003.) Combat jets often have very low-bypass ratio turbofan engines though. A true turbojet has a 0 bypass-ratio; a lot of turbofan fighter jets have bypass-ratios under 1, while the engines on a 787 have a bypass-ratio of 10. https://en.wikipedia.org/wiki/Bypass_ratio#Engine_bypass_ratios https://en.wikipedia.org/wiki/Bypass_ratio#Engine_bypass_rat...
- falcolas 6y ago
  I should clarify, when I'm saying "jet", I do mean turbofans. And turbofans still include a jet engine, but the output turns a turbine which rotates the fans.
  - catalogia 6y ago
    Turbojets, turbofans, and turboprops all use gas turbines. The "jet" in this context refers to the action of the exhaust, not the mechanism creating the exhaust (which is the gas turbine.) Turbojets and Turbofans both create jets of hot exhaust gas to produce thrust. Turbojets produce thrust exclusively with this jet of exhaust gas, while turbofans produce some [often most] of their thrust by using some of the turbine's output to turn a ducted fan. Turboprops don't produce any meaningful jet of exhaust gas, instead using the output of the gas turbine to turn a propeller. Related to turboprops are turboshaft engines, which turn a power transmission shaft instead of a propeller directly. In some cases, like the V-22 Osprey, the line between a turboprop and a turboshaft is blurred. But some clear examples of turboshaft engines are in modern helicopters and Abrams tanks. There are some kinds of jet engines that don't use turbines. Ramjets and scramjets don't use turbines, but have 'jet' in the name because they produce their thrust using a jet of hot exhaust gas. Rocket engines produce jets of hot exhaust gas, but aren't called jet engines because.. reasons. > jet: A collimated stream, spurt or flow of liquid or gas from a pressurized container, an engine, etc. (Note that this makes turboprop engines not jet engines, but turbojet and turboprop engines are both gas turbine engines.)
krisoft 6y ago
"Jets are stupidly simple" Haha :D I don't know where that comes from. Jet engines are fiendishly complicated. If they are so simple can you explain to me how interlaced rows of stator and rotor blades turn pressure into gas speed? That one always stumped me. Or how do I make monocrystalline blades, and how can I QA them? Or what exactly a FADEC do during startup, and how do the controlled parameters change depending on atmospheric conditions? Also I heard that the injectors and the air flow in the combustion chambers is designed such that there is an outside layer of incomplete combustion creating a colder laminar gasflow to protect the chamber wall itself. How do I go about designing that? How do I cool the bearings? How does one get the rotational energy out from the centre shaft to drive an oil pump on the side of the engine? I mean these are just the first questions which pop up in my mind when I think about jet engines. And I'm not even a jet mechanic. If you truly think that jet engines are simple, then I envy your intellect.
- falcolas 6y ago
  I was referring to the operational complexity of the final product, not in the design or manufacturing. They have two main moving parts - the jet turbine, and the turbine connected to the fan (or prop). This is in comparison to the hundreds of moving parts your average ICE has for the drive train alone, not including the electrical system that lives alongside it to facilitate timed fuel ignition. Jet engines are used on some older oil pumps because they can run for decades with minimal maintenance.
  - LargoLasskhyfv 6y ago
    [1] https://en.wikipedia.org/wiki/Geared_turbofan https://en.wikipedia.org/wiki/Geared_turbofan This Genius Invention Could Transform Jet Engines, 2015, 3m51s, Bloomberg QuickTake Originals [2] https://www.youtube.com./watch?v=8aPIEsnKb6o https://www.youtube.com./watch?v=8aPIEsnKb6o Rolls-Royce UltraFan technology, 3 shaft geared turbofan jet engine, 2018, 2m29s, MDx media [3] https://www.youtube.com./watch?v=6zD4uEdCkAk https://www.youtube.com./watch?v=6zD4uEdCkAk
  - mannykannot 6y ago
    The initial comparison was turboprops vs. turbojets, so switching the comparison to the undoubted complexities of internal combustion piston engines is beside the point. The 'jet' engines used on oil pumps etc. are actually not jet engines: they are gas turbines in which an additional turbine or turbine stage is used to extract rotational power - in other words, they are more like turboprop engines than jet engines. Nevertheless, I do disagree with the suggestion that turboprops are much less safe than turbojets, and I suspect that the author of that comment was confusing them with piston engines, which also (almost always) use propellers (increasingly, we are seeing turboprop singles replacing piston twins.) Finally, piston engines themselves have become much more reliable since the days when they were the only option.
redis_mlc 6y ago
> each prop has to rotate Pedant.