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Aviation’s Largest Piston Engine (2016)

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Re: Aviation’s Largest Piston Engine (2016)

#21

Post by mikestew »

dsfyu404ed wrote: post #4
nimbius wrote: post #2

>At full power, the XR-7755 generated a tremendous amount of heat. Speaking as a full time engine mechanic for a small chain of midwestern repair stores, this is the death-knell of every heavily customized car. Heck, 3/4ths of the engineering for a Dodge Hellcat or Mustang cobra is just to keep the thing cool enough that the driver isnt chased out of the cockpit. You cant idle them the same way you idle a Toyota...th…

I'm not seeing how crank and cam specs significantly affect cooling at idle all else being equal. Any cooling system that can work under load will be fine at idle. Edit: For something like a race-car that's trying to minimize weight/power loss by running the minimum radiator/fan necessary and depending on airflow from movement (or rely on the fact that you're only running 1/4mi at a time) I can understand. Still, tha…

Not cooling, but heat output, which the cooling system at idle cannot keep up with. As a simple example, you can retard the ignition timing enough on an otherwise sound car that the coolant will boil just sitting there idling (DAMHIK). The moral is, where the piston is at when the spark goes off makes a difference, as well which valves are opening when. Crank those knobs far enough toward the extremes, and you'll blow past the design limits of the cooling system. Yeah, your system used to be fine at idle, but now you fiddled with things. It's like the kids that throw a K&N air filter in their Civic and call it a day. No, ya idjit, you changed one thing and now you have to go change some other things to compensate. In this case, get a bigger radiator or a bigger fan.

Put another way, one does those mods to increase power output. Not all of the increased power is used to turn the wheels, a lot of it is turned to heat (just like a stock engine). More power, more heat, more cooling is required.

Re: Aviation’s Largest Piston Engine (2016)

#22

Post by funAtParties »

mc32 wrote: post #8
funAtParties wrote: post #5

Sometimes I think about aerial bombardment, and what that really meant during that period of conflict. When you think about the effort to concoct the compounds for the air war, and drop them on cities, with no guidance like lasers or anything, and then you look at the sheer tonnage dropped, and how indiscriminate it really was, you wonder how aerial bombardment is at all distinguishable from chemical weapons. It real…

It’s all well and good to examine these things while we have tjr benefit of having vanquished an enemy or enemies. Twiddling about this and whether we should bomb Hitler or Hirohito would either result in more total deaths or our defeats, neither would have been better alternatives. It’s not as if we’d go to Hitler and Hitohito and say stop killing indiscriminately in your conqured areas and we’ll stop bombing you an…

There's another aspect to the sheer insanity of the period that probably would be worth exploring, if only it were possible.

People were so mentally numbed and damaged by the carnage of the first world war, that the second world war was put on track by the leadership that had survived the carnage.

But looking at engines like this, and knowing that they ran on leaded AvGas, and knowing that leaded mechanization was the norm, you wonder if the psychotic leadership was actually an expression of lead poisoning from environmental factors. Just like all those crime curves that trend according to leaded gasoline bans, what if front line WWI veterans were driven psychotic by frontline exposure to heavy metals through exhaust fumes?

Re: Aviation’s Largest Piston Engine (2016)

#23

Post by mc32 »

funAtParties wrote: post #22
mc32 wrote: post #8

Earlier quoted context omitted.

It’s all well and good to examine these things while we have tjr benefit of having vanquished an enemy or enemies. Twiddling about this and whether we should bomb Hitler or Hirohito would either result in more total deaths or our defeats, neither would have been better alternatives. It’s not as if we’d go to Hitler and Hitohito and say stop killing indiscriminately in your conqured areas and we’ll stop bombing you an…

There's another aspect to the sheer insanity of the period that probably would be worth exploring, if only it were possible. People were so mentally numbed and damaged by the carnage of the first world war, that the second world war was put on track by the leadership that had survived the carnage. But looking at engines like this, and knowing that they ran on leaded AvGas, and knowing that leaded mechanization was th…

Rommel, IIRC, was initilly just one of those kids carrying spades as pretend arms (ok exaggerating a bit). People like him were not near a front during the first war. Hirohito’s men were in some conquest wars, but not heavy wars. So I’m not sure this applies.

Re: Aviation’s Largest Piston Engine (2016)

#24

Post by NeedMoreTea »

Gravityloss wrote: post #13

120 liter displacement. 4x9 = 36 cylinders and many valves and sparks plugs in each. As comparison an early generation single spool turbojet has pretty much one moving part. Nowadays there might be two or three spools and moving vanes and a thrust reverser. But aviation would never have been possible for the masses with piston engines.

Avro Lancaster, one of the two most successful heavy bombers of WW2 had 4 27litre V12 merlins, with proven reliability.

The Avro Lancastrian was a passenger variant of the Lanc and developed into the large bodied Avro York that had the range to replace a few of the old flying boat routes. Some lasted into the 60s on commercial routes.

The Lockheed Constellation had four 18 cyl radials, and being pressurised survived in commercial service even longer.

Neither had a turboprop variant.

Mass aviation was going to happen anyway whether the DH Comet arrived or not. It would have looked rather different, and perhaps not quite as endemic as now, but definitely mass aviation as we know it. Jets just hastened the process, and came at just the right time.

Re: Aviation’s Largest Piston Engine (2016)

#25

Post by funAtParties »

mikeash wrote: post #19
funAtParties wrote: post #5

Sometimes I think about aerial bombardment, and what that really meant during that period of conflict. When you think about the effort to concoct the compounds for the air war, and drop them on cities, with no guidance like lasers or anything, and then you look at the sheer tonnage dropped, and how indiscriminate it really was, you wonder how aerial bombardment is at all distinguishable from chemical weapons. It real…

The taboo against chemical warfare developed after a war that involved mass bombardment with both chemical weapons and explosives. I’m not qualified to discuss the reasons, but the people on the pointy end of the stick seem to have come away thinking that there’s a significant difference.

I'll argue that the surviving people on the pointy end of the stick haven't thoroughly considered how pointy conventional aerial bombardment gets.

Re: Aviation’s Largest Piston Engine (2016)

#26

Post by mikeash »

funAtParties wrote: post #25
mikeash wrote: post #19

Earlier quoted context omitted.

The taboo against chemical warfare developed after a war that involved mass bombardment with both chemical weapons and explosives. I’m not qualified to discuss the reasons, but the people on the pointy end of the stick seem to have come away thinking that there’s a significant difference.

I'll argue that the surviving people on the pointy end of the stick haven't thoroughly considered how pointy conventional aerial bombardment gets.

People who ended up on the pointy end of that stick in the next war still didn't make it taboo, even though they did with the weapon of mass destruction made famous by that war.

I see the argument that it ultimately doesn't make much difference how a vast bunch of civilians end up indiscriminately dead, but the people who actually experienced it seem to think differently.

Re: Aviation’s Largest Piston Engine (2016)

#27

Post by justin66 »

maxxxxx wrote: post #10
dsfyu404ed wrote: post #4

Earlier quoted context omitted.

I'm not seeing how crank and cam specs significantly affect cooling at idle all else being equal. Any cooling system that can work under load will be fine at idle. Edit: For something like a race-car that's trying to minimize weight/power loss by running the minimum radiator/fan necessary and depending on airflow from movement (or rely on the fact that you're only running 1/4mi at a time) I can understand. Still, tha…

Cars depend on air moving through the cooling system under load which means it's at speed. Cooling at idle can be a big problem for high performance cars. Going to the extreme, F1 cars have to be super careful not to overheat when stopped.

> Cooling at idle can be a big problem for high performance cars.

Or any air cooled car ever made. But the reality is that in a lot of designs, idling will test the effectiveness of the cooling system more than driving the car at speed. (Adding power only exacerbates such a problem. The OP completely fails to understand this)

It's much less of a problem than it used to be, with lots of cars including electric fans to help out the radiator, but it used to be standard to see a warning in the owner's manual about temperatures increasing in slow traffic or at idle.

Re: Aviation’s Largest Piston Engine (2016)

#28

Post by willyt »

funAtParties wrote: post #22
mc32 wrote: post #8

Earlier quoted context omitted.

It’s all well and good to examine these things while we have tjr benefit of having vanquished an enemy or enemies. Twiddling about this and whether we should bomb Hitler or Hirohito would either result in more total deaths or our defeats, neither would have been better alternatives. It’s not as if we’d go to Hitler and Hitohito and say stop killing indiscriminately in your conqured areas and we’ll stop bombing you an…

There's another aspect to the sheer insanity of the period that probably would be worth exploring, if only it were possible. People were so mentally numbed and damaged by the carnage of the first world war, that the second world war was put on track by the leadership that had survived the carnage. But looking at engines like this, and knowing that they ran on leaded AvGas, and knowing that leaded mechanization was th…

Quite a large area of France is still so heavily contaminated from WW1 that there is still an exclusion zone in place. https://en.wikipedia.org/wiki/Zone_Rouge

Re: Aviation’s Largest Piston Engine (2016)

#29

Post by maxxxxx »

justin66 wrote: post #27
maxxxxx wrote: post #10

Earlier quoted context omitted.

Cars depend on air moving through the cooling system under load which means it's at speed. Cooling at idle can be a big problem for high performance cars. Going to the extreme, F1 cars have to be super careful not to overheat when stopped.

> Cooling at idle can be a big problem for high performance cars. Or any air cooled car ever made. But the reality is that in a lot of designs, idling will test the effectiveness of the cooling system more than driving the car at speed. (Adding power only exacerbates such a problem. The OP completely fails to understand this) It's much less of a problem than it used to be, with lots of cars including electric fans to…

"Or any air cooled car ever made."

Are there still any being built? I thought the 911 was the last holdout until they also switched to water cooling.

"with lots of cars including electric fans to help out the radiator,"

I had that fan breaking once in my Miata and temperatures went into the red really quickly in LA rush hour.

Re: Aviation’s Largest Piston Engine (2016)

#30

Post by ethelward »

mc32 wrote: post #23
funAtParties wrote: post #22

Earlier quoted context omitted.

There's another aspect to the sheer insanity of the period that probably would be worth exploring, if only it were possible. People were so mentally numbed and damaged by the carnage of the first world war, that the second world war was put on track by the leadership that had survived the carnage. But looking at engines like this, and knowing that they ran on leaded AvGas, and knowing that leaded mechanization was th…

Rommel, IIRC, was initilly just one of those kids carrying spades as pretend arms (ok exaggerating a bit). People like him were not near a front during the first war. Hirohito’s men were in some conquest wars, but not heavy wars. So I’m not sure this applies.

> Rommel, IIRC, was initilly just one of those kids carrying spades as pretend arms

I beg your pardon? IIRC is a poor excuse when a ten seconds Wiki search proves you wrong.

He was a frontline lieutenant.

https://en.wikipedia.org/wiki/Erwin_Rommel#World_War_I

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