Munufacturing aircooled heads

[rogerwilko]

Anyone know of any film depicting the machining and casting of aircraft aircooled heads? I had a token look on youtube but no luck. douglas

 

[fastmongrel]

I have seen a video of Wright engines being built but it was a while ago so cant give you a link. I think they were R2600s. Not much help I know but might get you somewhere if you googled it rather than youtube searched.

 

[rogerwilko]

Thanks, I'll keep looking. Noticed in your avatar the BSA emblem. Working on this at the moment.

 

[Koopernic]

For what its worth I've read the fins were cut in by gang saws, presumably disks of silicon carbide? Pratt and Whitney were a machine tool company and it seems even if they didn't make every radial they made many of the machine tools.

The latter heads on the BMW 801 were cast in a vacuum, seemingly including fins. Obviously there must have still be some machining such as valve seats, head bolt holes but the idea of vacuum casting is to prevent the formation of gaseous inclusions. Not sure if the fins were still machined in after casting but the volks in charge of armaments production took a dim view of consumption of cutting materials.

 

[N4521U]

I'm thinking the fins are cast, mating surfaces machined. Maching the fins would be a slow process with a thre axis lathe. I'm sitting here looking at a T-6 cylinder assy and it plane to see they are cast.

 

[Shortround6]

Later P W and Wright cylinder heads were forged.
Bristol had gone to forging much earlier but that was because British casting practice (technique) was not as good as the US foundry practice. The cast or forged cylinder head blanks still had to be machined.
The amount of finning in sq in (or sq cm) per cylinder had tremendous increase during the 30s and 40s. Better fuel with higher performance numbers did little good in an air cooled engine unless you could keep the cylinder and head cool.

 

[rogerwilko]

Still searching but no film of the machinery in action? You'd think they would have had a war effort type film on manufacturing such things.

 

[swampyankee]

For what its worth I've read the fins were cut in by gang saws, presumably disks of silicon carbide? Pratt and Whitney were a machine tool company and it seems even if they didn't make every radial they made many of the machine tools.

The latter heads on the BMW 801 were cast in a vacuum, seemingly including fins. Obviously there must have still be some machining such as valve seats, head bolt holes but the idea of vacuum casting is to prevent the formation of gaseous inclusions. Not sure if the fins were still machined in after casting but the volks in charge of armaments production took a dim view of consumption of cutting materials.

Pratt Whitney Aircraft -- the company that made engines -- was not related to Pratt Whitney, the company that made machine tools.

 

[swampyankee]

I'm thinking the fins are cast, mating surfaces machined. Maching the fins would be a slow process with a thre axis lathe. I'm sitting here looking at a T-6 cylinder assy and it plane to see they are cast.

The fins on low-powered engines may have been cast; those on the R-2800 were machined. They used ganged, cam-controlled saws.

 

[Shortround6]

In 1925 P&W was pulling 45 per cylinder and had 1200 sq in of fins per cylinder and head, in 1932 they could pull 67hp per cylinder and had gone to 1500 sq in of fin, by 1940 they could make 100 hp per cylinder and had 3100 sr in of fin and in 1946 they could make 125 hp per cylinder and had 4300 sq in of fin.
Different manufacturing techniques were need from what had been common practice in 1925-30. The Forged cylinder head on a a R-2800 "C" engine started as a 70lb billet of aluminium. It went through 4 different forging steps, the first done by a 2000 ton press and the last three by 4000 ton presses with trimming done between steps. The "head" was then heat treated and initial machining done. Last steps were the machining of the cooling fins and by the time they were done 83 fins had been machined and 45lbs of material had been removed leaving a 25lb finished cylinder head.