[HN Gopher] The Complexity of a WW II P-47 Thunderbolt's Powerplant
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       The Complexity of a WW II P-47 Thunderbolt's Powerplant
        
       Author : philipkglass
       Score  : 27 points
       Date   : 2021-03-20 18:00 UTC (5 hours ago)
        
 (HTM) web link (lynceans.org)
 (TXT) w3m dump (lynceans.org)
        
       | Steven_Vellon wrote:
       | A relevant video on the same topic:
       | https://www.youtube.com/watch?v=IwqTN5fhMR8
        
       | olivermarks wrote:
       | Almost like a modern turbo drag racing setup!
       | 
       | I always wondered with all that duct work running the length of
       | the fuselage sending intake air back to the turbocharger, which
       | then fed cooled air back to carburetors serving 18 cylinders,
       | what enemy fire damage would do to this complex setup. Presumably
       | this doesn't have single points of failure in a sealed compressed
       | air system but it almost feels like race car level tuning for
       | optimal performance, let alone for limping home with fuselage
       | damage.
        
         | jandrese wrote:
         | I was wondering the same thing. What would a few bullets
         | through that huge air tube do to your power?
         | 
         | I recently had a pressure leak on my turbocharged car on the
         | air intake between the turbo and the block. It seriously
         | wrecked the performance. The engine was close to stalling and
         | my gas mileage dropped by half. These big radials aren't quite
         | as picky, but I bet you'd still feel the difference.
        
         | WalterBright wrote:
         | A P-47's engine was fairly resistant to battle damage. My dad
         | was a P-47 driver. One time it swallowed a valve, and the
         | engine kept running, just a bit of vibration.
         | 
         | For contrast, one time he was in a P-51 that swallowed a valve,
         | and he said he was lucky he was over the airfield, as that
         | airplane was going down promptly. The P-51 had a much more
         | fragile engine, I wouldn't want to fly one over water.
        
           | topspin wrote:
           | The US Navy mandated air cooled radial engines due to their
           | robustness. The US Army Air Force adopted water cooled V type
           | engines for performance. An air cooled radial can suffer
           | damage such as "dropping" a valve because each cylinder and
           | cylinder head is largely independent. There is no shared
           | water jacket, for instance.
        
       | aphextron wrote:
       | In the first diagram, how is that considered a supercharger if
       | there's no use of mechanical energy from the engine to drive the
       | turbine? Isn't that technically just a turbocharger?
        
         | GeorgeKangas wrote:
         | The word "turbocharger" was introduced to shorten the phrase
         | "turbine supercharger", whether driven by the crankshaft or by
         | the exhaust. Later, it came to mean "exhaust driven turbine
         | supercharger" pretty much exclusively.
         | 
         | I don't have any dates for these usages.
         | 
         | Edit: that p-47 powertrain is an absolute beast!
        
           | diarrhea wrote:
           | So when you have such a turbine supercharger driven by the
           | crankshaft, what does the turbine do at all?
        
             | sk5t wrote:
             | I think what you're getting at is that there is no turbine
             | (only an impeller) in the case of crank/belt driven units.
        
             | usrusr wrote:
             | A crankshaft driven charger would haven been called just a
             | supercharger, exactly like we do today. But we don't call
             | turbine driven chargers "turbine supercharger" anymore, we
             | call that a turbocharger.
        
           | jandrese wrote:
           | The crazy part is that by modern standards they aren't really
           | developing that much power. Sure this thing puts out 2,100 HP
           | (using 130 octane gas), but it needs a whopping _46 liters_
           | of displacement to get that.
           | 
           | A Veyron engine puts out about half the HP using _17%_ of the
           | displacement on worse gas. You can 't even buy 130 octane gas
           | anymore. The Veyron is a notorious fuel hog, but it has
           | nothing on a twin Wasp radial.
        
             | czch wrote:
             | But the P-47 is on fairly high power the whole time it's
             | running. Most Veyrons will never use 50% of their rated
             | power.
             | 
             | That being said, modern metallurgy really revolutionized
             | ICEs. Followed by computerized control.
        
         | jacquesm wrote:
         | I think back in the day the terminology may have been used
         | interchangeably, clearly that diagram is pretty old. The
         | article uses the term turbocharger consistently.
        
       | louwrentius wrote:
       | Very interesting!
       | 
       | Off-topic: Although I'm very into green energy, I have a love for
       | these extremely large displacement engines and their insane power
       | output. You can go nuts on YouTube with this.
       | 
       | - large radial engines like this one
       | 
       | - large train engines going north of 5000 - 10000 horsepower
       | 
       | Love the engineering, the size and sturdiness, the sound. Amazing
       | technology.
        
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       (page generated 2021-03-20 23:01 UTC)