5 ms·

Fuel saving solutions are always attractive in the industry. Originally it was thought jet engines would fail due to their fuel consumption, but the reduced mai

Fuel saving solutions are always attractive in the industry. Originally it was thought jet engines would fail due to their fuel consumption, but the reduced maintenance requirements made them more attractive.

WalterBright 7y ago
Yup. Piston aircraft engines indeed need tons of maintenance. A huge number of moving parts coupled with trying to minimize the weight and maximize the power is the cause. In WW2 the Germans fitted aircraft engines to their tanks, which worked great when the engines ran, but too often they didn't due to battlefield conditions. (Germany was also terribly short of avgas, which crippled those tanks.)
- newnewpdro 7y ago
  > In WW2 the Germans fitted aircraft engines to their tanks, which worked great when the engines ran, but too often they didn't due to battlefield conditions. (Germany was also terribly short of avgas, which crippled those tanks.) This sounded interesting so I skimmed the tanks mentioned in [0] and only found mention of prototypes exploring use of a turboshaft engine [1] from [2]. [1] explicitly states "none of these was fitted operationally", so I don't get the impression that these ever even encountered battlefield conditions before Panther II was canceled. [0] https://en.wikipedia.org/wiki/German_tanks_in_World_War_II https://en.wikipedia.org/wiki/German_tanks_in_World_War_II [1] https://en.wikipedia.org/wiki/GT_101 https://en.wikipedia.org/wiki/GT_101 [2] https://en.wikipedia.org/wiki/Panther_II_tank#Engine https://en.wikipedia.org/wiki/Panther_II_tank#Engine
  - zabzonk 7y ago
    Don't know about the Germans, but the British used modified aero engines quite extensively in tanks - https://www.wikiwand.com/en/Rolls-Royce_Meteor https://www.wikiwand.com/en/Rolls-Royce_Meteor
    - newnewpdro 7y ago
      That's pretty smart, using de-tuned aviation engines. But unlike what WalterBright is describing, these were appropriately reconfigured to not require high-octane fuel.
    - snovv_crash 7y ago
      Indeed, my grandfather was in one in Italy late in the war. From the stories he told, the crew one time got it up to 40MPH, then the crankshaft snapped.
  - WalterBright 7y ago
    I didn't mean a gas turbine engine, but a piston engine designed for aircraft. (Gas turbines don't run on avgas.) With a quick look I can't find a cite for my claim, just that the British did use Merlin aviation engines in some of their tanks.
    - newnewpdro 7y ago
      I couldn't find mention of anything else aviation-related in the per-tank pages, and the Maybach WWII engines page [0] doesn't speak to it either. Do you have any good references we can check out? [0] https://en.wikipedia.org/wiki/List_of_WWII_Maybach_engines https://en.wikipedia.org/wiki/List_of_WWII_Maybach_engines
      - WalterBright 7y ago
        I have a few hundred books on WW2, it's possible I'm mis-remembering it. I am ashamed :-(
        newnewpdro 7y ago
        No worries, I was just curious to read about it.
    - dredmorbius 7y ago
      You'd made a possibly related claim a few months back, if that stirs any memories: https://news.ycombinator.com/item?id=21953121 https://news.ycombinator.com/item?id=21953121
      - WalterBright 7y ago
        "I have seen desperate mechanics try to warm up their engines with a naked flame in the hope of inducing them to start." -- "Stuka Pilot" by Hans Rudel, pg. 50
- redis_mlc 7y ago
  > Piston aircraft engines indeed need tons of maintenance. Modern small piston aircraft engines under 250 HP have average TBO of 2,000 hours and can be operated beyond that with oil analysis. That's fine for commercial use, and piston engines only use 1/3 to 1/2 the fuel of jet engines, though that may be because of the use of a propeller. So you trade fuel efficiency for engine maintenance, and I think they'd average out. DC-3 operators can maintain their piston engines just fine with one mechanic. (Large turbofan engines like the 737 MAX uses are basically resurrecting the propeller in terms of moving a large volume of air, rather that relying on only a jet of air.) I don't think there is a lot of data for larger piston engines. 1,000 HP engines and larger in WW2 had issues at the time, but that was 75 years ago. Metallurgy and production methods have improved since then. Also WW2 engines were boosted (supercharged and water/alcohol-injected) and the military didn't care about longevity as airliners do today. For example, the American supercharged P-38 was the fastest fighter of WW2, while the version sold to Britain wasn't, and was a dog. Source: commercially-rated pilot, WW2 student.
  - sgent 7y ago
    I don't know what the data is, but the DHC-8/Q-400 is a fairly popular regional airplane outside the US, and depending on the model goes from 1300 - 5000hp. https://www.pwc.ca/en/products-and-services/products/regional-aviation-engines/pw100-150 https://www.pwc.ca/en/products-and-services/products/regiona...
    - redis_mlc 7y ago
      Both the DHC-8 and Q-400 are turbo-prop (ie. jet-engined) airplanes, not piston.
  - WalterBright 7y ago
    A Lockheed Constellation had 4 × Wright R-3350-DA3 Turbo Compound 18-cylinder supercharged radial engines, 3,250 hp (2,424 kW) each https://en.wikipedia.org/wiki/Lockheed_Constellation https://en.wikipedia.org/wiki/Lockheed_Constellation That's 72(!) cylinders. Then you've got the superchargers, variable pitch propellers, and on and on. It's a bit of a miracle one could get them all running at the same time :-/ BTW, Lindbergh flew the Atlantic on a single engine. He rejected multi-engine designs because the reliability would be halved. He selected the most reliable engine available at the time.

WalterBright 7y ago

Yup. Piston aircraft engines indeed need tons of maintenance. A huge number of moving parts coupled with trying to minimize the weight and maximize the power is the cause. In WW2 the Germans fitted aircraft engines to their tanks, which worked great when the engines ran, but too often they didn't due to battlefield conditions. (Germany was also terribly short of avgas, which crippled those tanks.)

newnewpdro 7y ago
> In WW2 the Germans fitted aircraft engines to their tanks, which worked great when the engines ran, but too often they didn't due to battlefield conditions. (Germany was also terribly short of avgas, which crippled those tanks.) This sounded interesting so I skimmed the tanks mentioned in [0] and only found mention of prototypes exploring use of a turboshaft engine [1] from [2]. [1] explicitly states "none of these was fitted operationally", so I don't get the impression that these ever even encountered battlefield conditions before Panther II was canceled. [0] https://en.wikipedia.org/wiki/German_tanks_in_World_War_II https://en.wikipedia.org/wiki/German_tanks_in_World_War_II [1] https://en.wikipedia.org/wiki/GT_101 https://en.wikipedia.org/wiki/GT_101 [2] https://en.wikipedia.org/wiki/Panther_II_tank#Engine https://en.wikipedia.org/wiki/Panther_II_tank#Engine
- zabzonk 7y ago
  Don't know about the Germans, but the British used modified aero engines quite extensively in tanks - https://www.wikiwand.com/en/Rolls-Royce_Meteor https://www.wikiwand.com/en/Rolls-Royce_Meteor
  - newnewpdro 7y ago
    That's pretty smart, using de-tuned aviation engines. But unlike what WalterBright is describing, these were appropriately reconfigured to not require high-octane fuel.
  - snovv_crash 7y ago
    Indeed, my grandfather was in one in Italy late in the war. From the stories he told, the crew one time got it up to 40MPH, then the crankshaft snapped.
- WalterBright 7y ago
  I didn't mean a gas turbine engine, but a piston engine designed for aircraft. (Gas turbines don't run on avgas.) With a quick look I can't find a cite for my claim, just that the British did use Merlin aviation engines in some of their tanks.
  - newnewpdro 7y ago
    I couldn't find mention of anything else aviation-related in the per-tank pages, and the Maybach WWII engines page [0] doesn't speak to it either. Do you have any good references we can check out? [0] https://en.wikipedia.org/wiki/List_of_WWII_Maybach_engines https://en.wikipedia.org/wiki/List_of_WWII_Maybach_engines
    - WalterBright 7y ago
      I have a few hundred books on WW2, it's possible I'm mis-remembering it. I am ashamed :-(
      - newnewpdro 7y ago
        No worries, I was just curious to read about it.
  - dredmorbius 7y ago
    You'd made a possibly related claim a few months back, if that stirs any memories: https://news.ycombinator.com/item?id=21953121 https://news.ycombinator.com/item?id=21953121
    - WalterBright 7y ago
      "I have seen desperate mechanics try to warm up their engines with a naked flame in the hope of inducing them to start." -- "Stuka Pilot" by Hans Rudel, pg. 50
redis_mlc 7y ago
> Piston aircraft engines indeed need tons of maintenance. Modern small piston aircraft engines under 250 HP have average TBO of 2,000 hours and can be operated beyond that with oil analysis. That's fine for commercial use, and piston engines only use 1/3 to 1/2 the fuel of jet engines, though that may be because of the use of a propeller. So you trade fuel efficiency for engine maintenance, and I think they'd average out. DC-3 operators can maintain their piston engines just fine with one mechanic. (Large turbofan engines like the 737 MAX uses are basically resurrecting the propeller in terms of moving a large volume of air, rather that relying on only a jet of air.) I don't think there is a lot of data for larger piston engines. 1,000 HP engines and larger in WW2 had issues at the time, but that was 75 years ago. Metallurgy and production methods have improved since then. Also WW2 engines were boosted (supercharged and water/alcohol-injected) and the military didn't care about longevity as airliners do today. For example, the American supercharged P-38 was the fastest fighter of WW2, while the version sold to Britain wasn't, and was a dog. Source: commercially-rated pilot, WW2 student.
- sgent 7y ago
  I don't know what the data is, but the DHC-8/Q-400 is a fairly popular regional airplane outside the US, and depending on the model goes from 1300 - 5000hp. https://www.pwc.ca/en/products-and-services/products/regional-aviation-engines/pw100-150 https://www.pwc.ca/en/products-and-services/products/regiona...
  - redis_mlc 7y ago
    Both the DHC-8 and Q-400 are turbo-prop (ie. jet-engined) airplanes, not piston.
- WalterBright 7y ago
  A Lockheed Constellation had 4 × Wright R-3350-DA3 Turbo Compound 18-cylinder supercharged radial engines, 3,250 hp (2,424 kW) each https://en.wikipedia.org/wiki/Lockheed_Constellation https://en.wikipedia.org/wiki/Lockheed_Constellation That's 72(!) cylinders. Then you've got the superchargers, variable pitch propellers, and on and on. It's a bit of a miracle one could get them all running at the same time :-/ BTW, Lindbergh flew the Atlantic on a single engine. He rejected multi-engine designs because the reliability would be halved. He selected the most reliable engine available at the time.