bobbysocks
Chief Master Sergeant
cool! thanks....I will look at it when I get off of work.
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There were many problems with the Packard Merlins and I am sure hundreds more that never got outside the factory. Setting up a plant to produce someone elses engine is a huge and very difficult undertaking. To find out Rolls Royce problems you would have to go back through all the problems in development of the Merlin and its predecessors. Both versions were excellent engines and both were operated by USA and UK in service. The differences amount to no more than quirks.There was also a problem with the US built Merlins where metal parts were were weakened during the manufacturing process. Exactly how, I cannot remember, but it involved contamination. Once the problem was identified, it was fixed. .
One thing that really pushes my buttons is the popular notion that Rolls Royce hand produced their engines while Packard were proper mass producers. The original orders for Spitfires Hurricanes and Battles were for hundreds not thousands of aircraft. If the Vulture Sabre and Typhoon had developed as hoped and Adolf delayed the war by a year then the Merlin would be viewed as an interesting pre war design of which a few thousand were produced. Apart from the Spitfire and Hurricane none of the big users of Merlins were supposed to have them, Lancaster Halifax and Mustang were designed for other engines while the Mosquito wasn't designed until after the outbreak of war. The US government and Packard would not get involved in building huge facilities to produce a few thousand engines over 4 years.
1. The Merlin would have been an important engine no matter what. The Sabre was too big for many airframes and too expensive.
The US certainly built plenty of R-1820s, R-1830s, R-2600s and V-1710s in addition to the R-2800s and R-3350s..
2 The real thing that saved the Merlin was better gasoline. Had the British been limited to fuel that would only support 12-15lbs of boost the Merlin would have seen much less use near the end of the war.
3 For some reason people want to believe that "their" nation built better engines or somebody else built lousy ones and will repeat any rumor that supports their position.
4 However as far as Rolls Royce hand producing their engines, it was much more a question of had selecting rather than had fitting.
Engine assemblers didn't "file" parts to fit. They simply sorted through a bin of parts (even if the parts were separated or cushioned and not banging into each other) and sorted out the number of parts they needed that would fit without hacking at them with hand tools!
AS in measuring piston diameter and cylinder bores and matching up suitable parts (while keeping the weights within limits).
5 Stanley Hooker in his memoir says that Ford of England built parts to tighter tolerances than RR did. Ford didn't have the trained labor force to do the hand selecting and every piece had to be totally interchangeable with every other piece of that part number. This was when Trafford Park was being set up. I have never read anything about RR tightening up their own allowable tolerances on parts but it might not be surprising to find out they did.
2 I think that is a chicken and egg situation common in engineering and technology, improved superchargers demanded improved fuels which prompted experiments on further improved superchargers and fuels. The result in 1945 could not have been dreamed about in 1937.
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I have no idea why (or at least that I can prove) but the Merlin, Griffon and Allison all were able to run at boost pressures much higher than most other engines, only the R-2800 came close.
Just a question, can you directly compare compression ratios/boost levels of sleeve valve and poppet valve engines with the scavenging and combustion chamber shape being so different.True but I was also thinking of the Sabre with maxed out, even post war, at about 65in ( Sabre VII) and the Hercules and Centaurus engines which seemed to max out the mid to upper 50s even 7-10 years after the war ended. None of the Wright engines ever seemed to go past 60 in either. (1525hp R-1820 excepted?)
True but I was also thinking of the Sabre with maxed out, even post war, at about 65in ( Sabre VII)
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A great illustration of what total war means. I doubt if many would see any connection between professors of chemistry and their technicians beavering away in labs ith their knights of the sky in fighters and bombers. Some may even have considered them draft dodgers and shirkers.I agree with your points however to elaborate on the fuel issue
The production of high performance number fuel required both good feed stocks and large quantities of special compounds. You can't just add more lead to mediocre feed stock.
The US and British changed the allowable blends of 100/130 several times in order to stretch production of the 100/130 using lower quality feed stocks. Sometimes extra refinery procedures could help out.
However 100/150 or 115/145 in large amounts required tens of thousands of tons of steel for extra refinery equipment and had to be balanced against ship production or other needs ( you can't use melted down I beams or railroad rail for refinery equipment) and obviously has to be planned for well before it it used in service.
They were fooling around with triptane in WW II but it was very expensive and to use it as a major component in aviation fuel, instead of an additive, would have required even more tens of thousands of tons of steel to make a major production plant.
Being able to make a fuel in batches of a few hundred gallons doesn't mean you can make it in batches of hundreds of thousands of gallons.
I have no idea why (or at least that I can prove) but the Merlin, Griffon and Allison all were able to run at boost pressures much higher than most other engines, only the R-2800 came close.
That , and two of the smaller lorries used by the military used the Meteor engine
Just a question, can you directly compare compression ratios/boost levels of sleeve valve and poppet valve engines with the scavenging and combustion chamber shape being so different.
Great post S/R, I had in mind my experience with two/four stroke engines. They have compression ratios port opening and closing times but they do not exactly compare. Also for reasons you state about the lubrication of the sleeves etc the oil took a lot more cooling than poppet engines.Maybe not but if power is in proportion to the amount of fuel/air burned (some engines used extra fuel as an internal coolant) then power has a pretty close relationship with the amount air flowing through the engine.
rpm times the size of the cylinders times the weight of air (and fuel) per cylinder filling per unit of time. higher pressure means a higher weight of air/fuel per cylinder filling (intake/power stroke)
Yes higher compression gets more power from the same amount of fuel burned but the difference in power is much smaller than increasing the amount of fuel and air burned.
Maybe the sleeve valve does allow for better cylinder filling but filling the cylinder when you have 24-40lbs of pressure in the intake manifold/intake ports is a lot different than when the descending piston is trying to suck air from a manifold with less than 15lbs pressure (normal pressure at sea level) like a non-supercharged engine.
The real difference for high power using large amounts of boost may have been cooling problems with the sleeve valve system.
In a normal cylinder the heat path is through the cylinder walls (one piece) and either into the coolant for a wet sleeve liquid cooled engine or into the fins on an air cooled engine. With the sleeve valve the heat has to go through the sleeve, through the oil film between the sleeve and jacket (either water cooled or aircooled.
It may be this extra "layer" and the need to keep from over heating the oil the that limited the boost in the sleeve valve engines.
Just a theory.
pbehn
I could not agree more. My neighbor made it back "more times than he wanted to remember" with R-1820's wounded or dead. He told me he came back "a few times" on just 2 good engines, hopefully, like you said, these were examined and useful information was obtained from them.
What absolutely kills me are the pictures from the Pacific B-29 bases, they had so many dead R-3350's, they were just put in big piles. But everyone already knew about the problems with that engine from the start.
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That is colder than any temperature I have experienced in UK.
Oh I was careful with my words swampy, I said in UK. However on the coldest night recorded in Northern England (-21C 1978) I spent the night with my girlfriend in Redcar and then rode a 350cc Yamaha to Hartlepool about 25 miles on iced roads. By the time I arrived at work I had lost all feeling in my fingers and toes. I didn't get off the bike I just let it fall over. By comparison -35C in Germany was a positive pleasure because the air is so dry and still however a UK car at the time only had anti freeze good enough for -25 and my cars water pump housing froze and cracked.You haven't missed much. Indeed, I suggest that it's your good luck you haven't. I've spent far too many seconds (about 300 of them) outside in -32C, and I'd rather not do anything like that again. I would like to remain attached to my toes.
Oh I was careful with my words swampy, I said in UK. However on the coldest night recorded in Northern England (-21C 1978) I spent the night with my girlfriend in Redcar and then rode a 350cc Yamaha to Hartlepool about 25 miles on iced roads. By the time I arrived at work I had lost all feeling in my fingers and toes. I didn't get off the bike I just let it fall over. By comparison -35C in Germany was a positive pleasure because the air is so dry and still however a UK car at the time only had anti freeze good enough for -25 and my cars water pump housing froze and cracked.