Warbird Information Exchange

What I would like to know is...................
Are the cylinder heads on radial engines, with all those intricate fins, sand cast or die cast

I know this may be basic knowledge to some people but I simply don't know so please don't be offended by my lack of knowlege.

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Wow, has it really been that long since I last visited?

Hi,

If memory serves me correctly, the molds for both the fin section and the head section are sand cast and then machined. It's been a long time since I played around radial engines though. Also, I do not think that there is any "new" manufacture of radial engine cylinders currently being done, though I could be wrong again. But I think with the onset of the jet age, piston engine manufacturer's slowly ceased production of most of their former radial's. And when the civilian market caught up to the military as regards aircraft engines and technology, then production pretty much ended. I do know that many engines still remain in their "pickled" state and those that have seen service in one form or another have seen numerous overhaul procedures done on their respective engine parts.

Hope this helps, even though it may be a wee bit off to the side of the topic.

Paul

ECI makes new 1340 cyl for, last i checked , about $2000 each

Thanks for the quick replies, I really was only wondering how they were made.

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Wow, has it really been that long since I last visited?

With today's high speed machining capabilities, just hogging out new cylinders from billet stock is about as cost effective as casting. We wanted to cast some equipment modules (about 4"w x 5"h x 10"l, with two seperate cavities) for some instrumentation work years ago...found out it was cheaper to go down to our inhouse scrap yard and get 6" plate cut-offs and hog out the modules from those. One guy spent about 10 hours working on the program for our Maho 800 5 axis mill. After that he could set up the one fixture and completely hog out, drill and tap all the screw and pin holes for 8 modules in about 3 shifts. He did the programming and hogged out 26 modules for the quoted cost of the pattern alone for doing sand casting.

Total off subject but a related engineering question cvairwerks...are the
Texas Air Factory's Hayabusa landing-gear mountings being produced
from billet, or forgings?

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Airnutz,

A friend of mine told me about those aircraft being scratch built. And from what he told me that he got from a vist there, was that most off of the castings were machined out of billet stock. Due to today's modern machining techniques it would be faster and in the long run less expensive to accomplish this in this manner versus casting then machine work.

However, and I do know this from past experiance. ANY billet stock that is to be machined for aircraft MUST be a certified billet. In other words, that big block of aluminum or whatever material MUST be certifed by ultrasonic inspection to ensure that no voids, inclusions, or other imperfections exist prior to machining.

Hope this helps with your info.

Paul

Hi All,
A word of caution here, just because it may be more cost effective to hog a part out of solid stock on a CNC machine does not always produce an
part equal in mechanical properties to the original produced from casting.
You must remember the reason a casting is selected in some cases is for it's higher yield strength and lighter weight.
In almost all cases even in the AISI 4340 AQ Bar stock or billet the yield strength is substantially less than the untimate tensile strength resulting in bending before breaking. This sounds like maybe a good thing but sometimes you don't need something bending or stretching as in cylinder heads when it should remain stable.
So keep in mind sometime depending on the part it may require substantial re-engineering to produce a part made from bar or billet that would be equal to the casting in strength.
Tom

HI BIG DIFFERENCE BETWEEN A CASTING AND A FORGING.CASTINGS ARE GREAT FOR NON STRUCTURAL ITEMS, BUT THE PARTS THAT HOLD YOUR WINGS TAIL ECT ARE FORGINGS.CASTINGS ARE MUCH WEAKER,ARE MORE LIKELY TO HAVE FLAWS,IMPURITIES,PITS,AIR BUBBLES ECT.A FORGING IS A CHUNK OF METAL HAMMERED OR PRESSED INTO A FORM/MOLD COMPRESSING AS MUCH MATERIAL INTO THE PART MAKING IT MUCH DENSER AND STONGER THAN A CASTING.GO TO YOUR LOCAL LIBRARY OR CHECK THE INTERNET FOR A MORE DETAILS.THANKS MIKE

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