Comments by "Keit Hammleter" (@keithammleter3824) on "VisioRacer" channel.

Another important factor: in the 1920's, poppet exhaust valves set a limit on engine performance because doing anything to increase power output for a given cylinder size led to exhaust valves being overheated and burning out. Sleeve valves don't have this problem and experts including Harry Ricardo promoted sleeve valves as the future. However, in time for WW2 engines such as the Merlin, sodium filled stellite exhaust valves were developed, which had improved heat flow into the cylinder head and withstood higher temperatures anyway. These rendered sleeve valves obsolete virtually overnight.
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The USA was slow to use diesel fuel in trucks because they taxed gasoline at a low rate, a lot less than on diesel fuel. Thus their tax regime masked the cost saving in using more efficient diesel engines. It should be noted too that the USA is an extremely conservative, change resistant, country. This shows up in many ways, apart from sticking to gasoline:- sticking to 8-track tapes long after the market died elsewhere; 8-bit s-100 CP/M computers selling long after the world changed to 16-bit DOS computers; and refusing to go metric.
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VisioRacer is quite right - inline engines have more of a problem with crankshaft torsional vibration. It wasn't a problem with the old American inline 8 car engines due to low compression design, and low power output. In the 1930's America, a long engine bay on a car was a status symbol. Post-war, long engine bays were considered ugly, and women drivers found long cars hard to park. So engines had to be shorter - hence V8's, not I8's, post war. An additional minor advantage of V-engines is lower friction. For any given cylinder swept volume, you would expect the power lost in friction would be directly proportional to the number of cylinders. However, for any given cylinder size and number of cylinders, the V-formation has less friction than the inline form due to the staggering of peak loads on each crank throw. For a while. I worked as the engineer for a dealer selling large industrial diesel engines. Over a whole range of an engine series, the cylinder size is always the same. One series we sold gave about 50 kW per cylinder, so if you needed 200 kW, you got an inline 4, if you wanted 300 kW, you got an inline 6, if you needed 400 kW, you got a V8, and if you needed 600 kW, you got a V12. And if you needed 800 kW, you got a V16. The V8 got the same size starter motor as the I4. The V12 got the same size starter motor as the I6. Of course the V16 had two starter motors fitted, each the same size as the one fitted to the V8 and I4. This is not the full picture though - for example the I4 cranked a bit faster that the V8. But the friction loads were close enough to allow starter motor standardization. The V engines needed only slightly larger starting batteries too. So, all up, a V8 is cheaper than an I8 for example.
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A diesel engine cannot pre-ignite, as ignition starts when fuel injection starts, so adding a turbo to stuff more air in works really well, significantly adding power output across ALL the RPM range while improving fuel economy. But stuffing air in under pressure is really much the same as increasing the compression ratio which in a gasoline engine makes for pre-ignition. So at low/medium RPM the boost has to be kept low, and the turbo can only be effective at high RPM where increased turbulence in the cylinder causes loss of heat and thus reduces the tendency to pre-ignite. So in a diesel, a turbo is good at the RPM you want in a haulage truck or an industrial application - more power and better fuel consumption. But in a gasoline engine, apart from high RPM racing, a turbo can't do much. With gasoline engines not in racing applications, if you need more power, the best way is just use a bigger displacement engine. It will work just as well and be more durable and reliable.
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@andrewwilson6085 To what end? These events were important in terms of effort and casualties, but Germany had essentially already lost the War by the time these events took place - industrially crippled and insufficient fuel to train pilots and deploy aircraft. These events would not have been different had Typhoons not existed as other aircraft in plentiful numbers could do ground attack. In the Battle of the Bulge, Typhoons played an important ground attack role, basically protecting British troops only, because at that time Typhoons were the best airborne firepower available, but other aircraft could have done the job. Much the same applies with D-Day landings. Can you cite a specific reference and summarise what it says?
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@Turnipstalk That's true in theory, however aircraft engines of WWII vintage were limited to about 7:1 so that they could use low swirl combustion for efficiency and so they could use supercharging/turbocharging. The Napier engines featured in this video had a 7:1 compression ratio, actually higher than for example the poppet valve Merlin, which had only 6:1. Both required fuel of at least 100 octane rating. In terms of combustion conditions, supercharging is much the same as raising the compression ratio, as is turbocharging, except that turbocharging is a little more efficient as it uses waste heat in the exhaust instead of taking some power from the crankshaft.
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That sounds like an urban myth or maybe you made it up. A typical adult dose to make you go is 15 to 20 ml - about one tablespoon. It is quite likely that mechanics with oil on their hands might wipe their mouths and ingest some oil, but it would be nowhere near a spoonful, even if it was 100% castor used. In any case, the digestive system has great powers of automatic adjustment and under regular ingestion will overcome any laxative cause. Those of us old guys who, like Joe Biden, are on a drug esopremazole long term (eg to stop chest pain) know that - it causes diarrhea but only for the first few days. When you stop taking it, you don't go for about a week. In WW1 it was said that pilots ingested castor oil blown back in their faces by the open design radial engines of the period. But considering they had to fly rickety cloth & string biplanes into enemy territory and get shot at, I reckon anyone would get the urge to evacuate regardless of what they did or did not ingest.
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@sandervanderkammen9230 ; Yes, I should have written "rotary" where i wrote "radial".
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@terrydepew1252 : My mother told me much the same story as your Dad. If I remember right she said it tasted really foul. It was the foul taste that made her behave more than the trots.
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@bruceparr1678 You are misled. Two important factors about efficiency:- # Aircraft engines could indeed be quite a bit better than 40% thermodynamic efficiency because they are designed to run at a specific RPM (usually about 2000) - thus turbulence, which is set by cylinder head and valve geometry, can be optimised. A car engine, and to large extent a truck engine, needs to operate over a wide range of RPM, so turbulence is necessarily a compromise. If it is enough at low RPM to prevent pinging, it is too much at high RPM. # Since the amount of heat lost is proportional to cylinder bore, but power is proportional to the cube of bore, it follows that, within reason (considering factors like con-rod mass), the bigger the bore the better. Those turbo-compound aircraft engines had cylinder capacity around 2.5 to 3 litres. Given that for car engines 3 litres is a moderately large size, if a car engine was optimised for highest thermodynamic efficiency, it should have only one cylinder. This would confer totally unacceptable vibration. And it would need to be large and heavy. 4 cylinders is about the minimum number of cylinders for a smooth ride in a car, 6 cylinders is better and that means the bore size has to be well under the optimum for efficiency. V8's were designed for cars, to further reduce vibration, and get more capacity in a short length, but there was, compared to 4 or 6 cylinders with the same total displacement, a fuel consumption penalty. When BMC were doing the initial design of the Mini Minor, they calculated that about 800 to 900 cc would give the performance needed. So they designed and prototyped a 3-cylinder engine in order to not take the bore too far away from the requirements of efficiency. On test they decided that vibration would be too high for market acceptance and stayed with 4 cylinders. You should note that supercharged, turbocharged, and turbo-compound aircraft engines were set up so that at sea level the amount of boost was minimal or non-existent. The system was set up so that a near constant amount of air-fuel mix was pushed into the engine regardless of altitude, i.e., by means of waste gates and other means, the boost increased as altitude lowered atmospheric pressure, so the engine was operating at sea level conditions even at maximum altitude. Note also that with aircraft engines, a couple of factors gave a few more percent efficiency that don't apply to car and truck engines. At altitude, air temperature is much lower. Engines thermodynamically work on the difference between combustion temperature and air temperature, so you gain a bit of efficiency at altitude. Secondly, the exhaust gasses act like a jet engine and impart a bit of thrust to the airframe. It's small but it does count. A typical car engine has a thermodynamic efficiency of around 22 to 26%. If there was a way to easily increase it to 40%, manufacturers would have long since done it, and we would all be getting 40 - 50 miles per gallon. Fact is, there isn't. Except for one thing: If the vehicle is a hybrid, i.e., an engine driving a generator charging a battery, the battery in turn feeding an electric motor driving the wheels, the engine can be optimised for a specific RPM and always operated at that RPM. But would you want a car where the engine is always screaming at high RPM, regardless of how fast or slo you are driving?
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Being made in such small numbers there is no way you could consider this engine a war winner. Despite extreme effort, the whole British airborne effort didn't count for much anyway. World War II was won by the much larger and better designed efforts of the United States and the Soviet Union. The Brits contributed almost zero to the war in the Pacific anyway.
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@robertnicholson7733 ; I can only speculate, though with some certainty. The Pennine and the Exe are really the same engine in different sizes. Intended for commercial heavy transport use they were air cooled to reduce maintenance costs. Maintaining closely to a design operating temperature is more difficult than with liquid cooling - possibly some engineer decided to pay safe and use sleeve valves. The Eagle series of engines originated back before sodium filled poppet valves became available. Design on the Exe started in the mid 1930's - when the industry was in transition from plain stellite poppets to sodium filled poppets. Basic features eg inline, V, X, etc type of cooling, type of valves get set early in the design process as once decided, changing basically means starting all over again. No more aircraft engines with poppets or sleeves came from Rolls Royce after these because Rolls Royce changed to making jet engines. The Merlin & Griffin were as good as is possible - so close to the theoretical maximum thermodynamic efficiency you couldn't make a better piston aircraft engine to run on 100 octane juice now.
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@throwback19841 You must have been a very bad boy.
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