Fw190D/Ta 152C vs. Latest Generation Allied Fighters

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GregP

I'm not really aware of the WW2 sports scene but I have always wondered if modern ignition units, bearing materials, piston, piston ring valve materials along with modern oils/treatments/additives would raise those low rpm levels without problems arising.
I know engines can be limited by cylinderhead flow efficiency rates too but as most of these motors seem to run either super or turbo charging is that a big factor?
Or is it a case of throwing everything else out if you were to try to fit stuff like titanium valves etc?

Sorry if this is way OT, I hope you guys don't mind, but I'm just wondering (do such things exist, do people commission bearings to be manufactured to modern standards?).
 
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I can address some of these questions.

The steel in Allisons (and Merlins, Pratts, etc. not limited to Allisons) is better than ANY steel we get today. We have crankshafts that have sat in open air inside the hangar for 20 years and have not rusted. The steel is VERY hard and wears VERY well. There are people who say we can do better than we did in WWII today, but the steel we SEE doesn't bear that out at all. Modern rings are not as good, but we have had some made to our specs and they wear OK, if not as good as originals as a test. Modern bearings are nothing compared with WWII bearings. We know about 4-5 shops that can overhaul WWII bearings and plate them to spec ... and yet we still have to scrape them (a lost art in most places) so they test OK with plastigage.

So, the WWII stuff is very hard and long-wearing and the new stuff simply isn't. I can tell you this, go buy an old Williams or Cornwell wrench and then get one from Home Depot or Lowes and THEN try to turn something that is rusted together. The old wrenches will DO it and new ones will too, but not without damage. The old wrenches are unmarked.

Gimme and old Kwik-Way valve ginder before a Sioux, and BOTH are out of production now. If you don't HAVE them, you can't overhaul the old valves with any confidence. If you can't run a manual engine lathe, you can't DO an overhaul. You need to be able to remove a broken stud and not ruin the hole and threads. There are a lot old "repair" techniques that are less well known today, but are required to build an Allison or a Merlin or a Pratt, Wright, or BWM or DB. You need surface ginders and knee mills and the ablity to use them properly. That is fading today.

We found a Sunnen line boring machine and bought it as scrap. After overhaul (can still get parts), sanding, prime, new paint, etc. ... it looks and runs like new. So we CAN line bore a Merlin or an Allison that had had a rod put through the case. Wr won't DO it yet for Allisons that go into aircraft because we don't HAVE to yet, but we CAN. Right now, a repaired case is a good tractor or boat engine ... not one to go FLY.

Heck, they are flying Merlin parts today that they would have thrown away 20 years ago. The same will come for the Allison, but not for awhile. We wish they had the parts they threw away now ...
 
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Sorry Greg, I disagree.

If you have a sufficient need a modern steel manufacturer could match the composition and properties of the Allison crankshaft steel. Probably what you are comparing to is cheaper stuff.

Spanners (wrenches): I am going to go out on a limb and say that Lowes and Home Depot sell cheap grade products to home handymen, rather than products for professionals.

I know nothing of valve grinders. What do professional car engine builders use?
 

Sorta getting back on thread, do you know how the steels and alloys used by the Allied aero engine manufacturers during WW2 compare with those used by the Germans? Reading a NACA report on the supercharger of a Junkers Jumo 211F there are a few comments on how rough and unfinished some components were.
 

I would assume a higher chromium content in WW2, modern steels use more exotic additives, and if you specify it you can use far more advanced metals these days with far more exact quality control than they ever could back then!
 
Thanks.
Really interesting stuff guys.
Somehow I had it in my mind that 2000rpm rev ranges were down to primitive materials oils nothing like what a good set of modern ignition components, bearings, pistons, rings, valve springs titanium valves would allow.
 
Part of the rev limit was due to the size of the cylinders. The gas/air mixture burns at a certain number of feet per second or minute. You want the burn to complete with the piston at about 20 degrees after top dead center. This limits the bore size to just over 6 in even with dual ignition. Piston speed was limited to around 3000fpm (with a few exceptions).

For a little perspective a 1938 Auto Union 3-Litre V-12 Grand Prix engine turned 7,000rpm and had a piston speed of 3444fpm. The 1939 Mercedes-Benz 3-Litre V-12 Grand Prix turned 7500rpm but due to a 5mm short stroke it's piston speed was almost identical.
Neither ran on gasoline and the Mercedes weighed 1.26lb per HP. It was a rare race car engine that had a better power to weight ratio than most WW II high powered aircraft engines until the late 50s or 60s.

A lot of the high revving post war race care engines had strokes under 50mm, 1/3 that of a Merlin or Allison. Modern Materials help. SO does the fact that with a race car you can walk back to the pits after a rod goes through the side of the block.
 
Hi Wuzak,

Not saying your are wrong, but apparently nobody has sufficient need since the steel we se today is not anywhere NEAR the WWII steels. They may well be able to MAKE it, but if they DON'T, what is the difference?

In 1965, you could buy a drill press in Sears from Craftsman and it was pristine. Today the floor models are rusted while on display! It doesn't stop there ... it goes on.

So, while you may be right, you are not in a practical sense. That is, if I order a modern part, it doesn't come in TO ME anywhere NEAR as good as an old part ... even if it COULD ... it just DOESN'T. Ergo, it is of a lower quality ... because that is what I experience.

One example ... the water jacket hold down nuts have very little clearance in the Allison. You need a 7/8" wrench that is heavily ground down so it clears. An old Williams or Cornwell will do the job. A modern Craftsman will do the job, once ground down, for a few heads ... and then fails. I have ground down two so far and one has failed and the other seems to be about to do so by the feel of it (getting soft at the end of travel). I already have plans to get another. The old Williams wrench just keeps on working despite being very thin around the diameter and here's the thing ... it has been good for more than 20 years at the same task, while ALL otehrs have failed very quickly.

So... if they CAN do it right today, why can't I FIND it and GET it? And at a resaonable price? It's cheaper and works better to find the old wrenches at a yard sale and then use them forever.

Sorry, you may well be right, but I see no evidence of it. So. I stand by what I said as far as I can tell.

Maybe send me some Tasmanian wrenches that are of good quality and I can verify that by using them and having them last as well as the old Williams / Cornwell / Snap On stuff we have in the shop ? ... Most will need to be ground down for clearance in tight spots. I can DO that, but the wrenches usually then fail unless they are old steel.

Fortunately, we can still find old steel tools at auctions and yard sales.
 
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GregP said:
Not saying your are wrong, but apparently nobody has sufficient need since the steel we se today is not anywhere NEAR the WWII steels. They may well be able to MAKE it, but if they DON'T, what is the difference?
Click to expand...

Price is one factor.


GregP said:
In 1965, you could buy a drill press in Sears from Craftsman and it was pristine. Today the floor models are rusted while on display! It doesn't stop there ... it goes on.
Click to expand...

I would surmise that is more to do with the care taken by sales staff to keep the tool in that condition rather than the materials used. And/or the new ones are cheap because they use cheap materials.



How do you define good? Material specs? Tolerances? Shininess?



I would suggest that the Craftsman is a cheapie too.



We don't have any indigenous tools. Stanley Tools used to manufacture here, not sure if they do any more. Snap On is apopular brand - why don't you get them? Sidchrome is also a famous brand in Australia

Sidchrome

I can't speak to the merits of these brands, since I personally am not on the tools. I will try to find out some more.
 
Here are two NACA reports from the 1940s on radial engine cylinder barrels and tests of Nitrided-steel piston rings, plus a NASA history and analysis of steel roller bearings from 2012.
 

Attachments

  • Roller Bearing Steels NASA.pdf
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  • Heat transfer tests steel cylinder barrels aluminium finning NACA 1940.pdf
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  • Nitrided steel piston rings NASA 1945.pdf
    1.8 MB · Views: 81
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As a man who earns his living using spanners and owns probably £60,000 plus worth of tools aquired over nearly 40 years I can honestly say that if you buy a piece of cheap crap from a department store stamped out of god only knows where it came from steel in some place no one has ever heard of in China you shouldnt be surprised it breaks. I would only use junk like Craftsman as a door stop.

I still have to buy tools occasionally and will only touch Gedore spanners, Wiha Screwdrivers and keys and Koken sockets these days I know they will last and will bend rather than crack and risk me busting a knuckle. Even Snap On isnt what it was twenty years ago now they concentrate on the shiny tool colectors rather than selling stuff to mechanics.

The reason why old tools are good is simply because all the stuff with a flaw in it has broken long ago and been binned plus steel ages the crystalline structure changing slowly over the years and becomes better with use.
 
I aggree in many ways and stick with the ones that work. For us, the older wrenches and steels work the best. I have seen very little evidence of great modern steel that doesn't come with a ridiculous price.

Gedores are nice but about 4 times as expensive as the excellent-quality older tools we are getting. Right now, I'll stick with the older stuff since we can find it and still get it. When that goes away, we'll HAVE to identify suitable alternatives, won't we?
 
I remember watching a documentary about restoring a Bf 109. The museum sent the original engine to Rolls-Royce, who, went they sent it back, informed to museum to take especial care of the engine because the driveshaft (I think it was) was so finely engineered that RR could not replicate or replace it. And just think how many DB engines were produced wartime under conditions at times bordering on apalling.
 

Groan not this old chestnut again. Shock horror a company that makes gas turbines out of 21st C materials and hasnt built a piston engine in 60 years couldnt make a crankshaft. Its like sending Apple a Commodore 64 and expecting them to make a new proccessor for it.
 
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