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rwahlgren
Joined: 15 Aug 2003
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 Posted: Wed Dec 30, 2020 18:06 Post subject: Crankcase |
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| When did Wright start using steel crankcases? |
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kmccutcheon
Joined: 13 Jul 2003
Posts: 298
Location: Huntsville, Alabama USA
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| Posted: Thu Dec 31, 2020 08:26 Post subject: |
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With the G100 Cyclone, about 1937.
1938 G100 Sales Brochure
The construction is covered in a patent by Rudolph Daub, who made application in 1937.
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Kimble D. McCutcheon |
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rwahlgren
Joined: 15 Aug 2003
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| Posted: Thu Dec 31, 2020 14:29 Post subject: |
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What about Germany? Were the Americans first or ?
Edit to correct a miss spelled word.
Last edited by rwahlgren on Thu Dec 23, 2021 19:30; edited 1 time in total |
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kmccutcheon
Joined: 13 Jul 2003
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| Posted: Thu Dec 31, 2020 14:46 Post subject: |
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I don't know. Looks like you'll have to do some research...
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Kimble D. McCutcheon |
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rwahlgren
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| Posted: Thu Dec 31, 2020 15:01 Post subject: |
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| And makes me wonder why PW didn't use it. All most all PW important people came from Wright? |
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kmccutcheon
Joined: 13 Jul 2003
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Location: Huntsville, Alabama USA
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| Posted: Thu Dec 31, 2020 15:30 Post subject: |
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| rwahlgren wrote: | | Allmost all important P&W people came from Wright? |
Only in the early years. P&W was formed in 1925; this was 1937.
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Kimble D. McCutcheon |
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dpennings
Joined: 10 Dec 2016
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| Posted: Sat Jan 02, 2021 05:14 Post subject: |
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| I took a look into my book (Kyrill von Gersdorf, Kurt Grassmann, Helmut Schubert: Flugmotoren und Strahltriebwerke) and found no direct information, but a section view of the BMW 801. The walls of the crankcase look quite thin, so it might be made out of steel/cast iron. Also on photographs, the crank case are painted, which is more likley done on steel parts than on aluminium. |
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kmccutcheon
Joined: 13 Jul 2003
Posts: 298
Location: Huntsville, Alabama USA
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| Posted: Sat Jan 02, 2021 07:59 Post subject: |
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While the BMW 801 had a steel crankcase, the R-1820 G100 was in PRODUCTION in January 1937. rwahlgren wanted the first use.
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Kimble D. McCutcheon |
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rwahlgren
Joined: 15 Aug 2003
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| Posted: Sun Jan 03, 2021 16:27 Post subject: |
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| dpennings wrote: | | I took a look into my book (Kyrill von Gersdorf, Kurt Grassmann, Helmut Schubert: Flugmotoren und Strahltriebwerke) and found no direct information, but a section view of the BMW 801. The walls of the crankcase look quite thin, so it might be made out of steel/cast iron. Also on photographs, the crank case are painted, which is more likley done on steel parts than on aluminium. |
801 is steel case and is why I asked the question. See Calum's book.
Unless it is a 300 series stainless steel most all metals need paint, or surface protection of some sort, especially aluminum, just open the hood of an older car with aluminum engines and accessories if they aren't protected with oil or paint, have been outside in the elements they are usually very corroded. I think even Magnesium corrodes less than some aluminums do. |
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dpennings
Joined: 10 Dec 2016
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| Posted: Mon Jan 04, 2021 14:10 Post subject: |
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actually, the cylinder head of the BMW 801 are made of an aluminum alloy wich is very corrosion and heat resistant and was used on motorcycles (the Boxer engines). I've been searching this alloy (I read about it a couple of years ago).
On car engines, aluminum parts are usually not protected and the salt on the streets (maybe unkown for people from California....) takes its toll...
Seams like, crank cases of radial engines are more stressed than those of inline engines, otherwise they wouldn't be made of steel...
Its remarkable that these late radials contain much more iron than aluminum, the cylinders are made of steel as well. The cylinder heads are the only mayor highly stressed parts out of aluminum. |
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rwahlgren
Joined: 15 Aug 2003
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| Posted: Mon Jan 04, 2021 19:35 Post subject: |
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| dpennings wrote: | actually, the cylinder head of the BMW 801 are made of an aluminum alloy wich is very corrosion and heat resistant and was used on motorcycles (the Boxer engines). I've been searching this alloy (I read about it a couple of years ago).
On car engines, aluminum parts are usually not protected and the salt on the streets (maybe unkown for people from California....) takes its toll...
(Seams like, crank cases of radial engines are more stressed than those of inline engines, otherwise they wouldn't be made of steel... FROM DPENNINGS POST)
Its remarkable that these late radials contain much more iron than aluminum, the cylinders are made of steel as well. The cylinder heads are the only mayor highly stressed parts out of aluminum. |
All Pratt & Whitney Radial engines have Aluminum Crankcases.
But of course they need thick sections to handle the load, and is why some Radial engines can compete with steel, not knowing for sure but I am thinking both the Steel and Al cases weight very close to the same weight.
With steel they get the same or better strength from less material.
(Seams like, crank cases of radial engines are more stressed than those of inline engines, otherwise they wouldn't be made of steel... FROM DPENNINGS POST)
In some areas maybe so, cylinder attachment would be the number 1,That I can think of. The well known inlines have no push rods, radials do, that is more cyclic loading .
Check out Kim's Chrysler engine book, inline crankcases have to absorb torque, through out the length. Forged and machined radial engine crank cases are much stronger than a sand cast crankcase.
Last edited by rwahlgren on Wed Jan 06, 2021 12:06; edited 1 time in total |
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dpennings
Joined: 10 Dec 2016
Posts: 48
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| Posted: Tue Jan 05, 2021 14:27 Post subject: |
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| the crankcases of radials are full of thread holes, therefore steel makes much sence. You can use bolts with higher strenght in steel thread holes which can save quite a lot of weight. You also get rid of the thermal expansion problems. |
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kmccutcheon
Joined: 13 Jul 2003
Posts: 298
Location: Huntsville, Alabama USA
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| Posted: Tue Jan 05, 2021 16:22 Post subject: |
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| dpennings wrote: | | The crankcases of radials are full of thread holes, therefore steel makes much sense.... |
Replacement of crankcase studs with capscrews was also a huge cost saver. Each stud had to be inserted by hand. Many of the studs were stepped, which made them quite expansive and difficult to maintain.
Wright steel-crankcase cylinder attachment was largely covered by US patent 1,944,219, an invention by prolific engine designer Roland Chilton. During one year of WWII Chilton was the highest paid man in the United States. Each of those spherical cylinder base cutouts required a spherical washer (#20 on the diagram) and Chilton got a 2.5% royalty on the price of each washer (about a penny).
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Kimble D. McCutcheon |
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dpennings
Joined: 10 Dec 2016
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| Posted: Wed Jan 06, 2021 12:05 Post subject: |
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| I have to say, that idea is brilliant, I will keep it in my mind and might reuse it somewhere else in future... He deserved every penny for it! |
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rwahlgren
Joined: 15 Aug 2003
Posts: 323
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| Posted: Wed Jan 06, 2021 18:51 Post subject: |
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I would like to know how they maintained a decent finish in those radiused holes? Especially in those days that would be a pretty slow machining operation. Easy to have the cutter leave chatter marks, because of the large area for the size cutter used, also one side is pulling down and other pushing up on the cutter, surface speed is much slower towards the shank and or center of the cutter. But then its just speculation until you actually do the cut.
It would be horrible doing that on a manual milling machine of any sort back then using an indexing head. Rather than the cutter they show in the Patent, a multiple drilling machine using reverse counter sink cutters with the spherical ground on them would be much faster, back in the non CNC days.
After finding this looks like they would not use a manual machine.
https://www.youtube.com/watch?v=sBfFpcdyd5Q |
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