Allison v1710.

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Curious if anyone has found the drawings already scaled down or original detail drawings so a person could scale theirs elf. Thanks in advance.
 
Several years ago Bob DeFord built a Spitfire replica around one, that replica was written up in the EAA's magazine. That may sound like sacrilege, but Merlins are unobtanium and the Allison was available. He did a lot of mixing and matching on that bird, he might have something?

Nice guy, I met him when he and the Spit overnighted in my home town on his way to Oshkosh. It's not often that you get to see a Spitfire parked next to the runway in a small town. You might be able contact him through the EAA to see if he has any info.
 
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I will definitely look into this, thanks. I'm a rolls royce employee and we have a rolls royce allison heritage trust that I'm sure has documentation, but I don't know if they would share copies. Have to find out who the directors are and ask. Individuals may be more receptive than corporation. Thanks for info.
 
I have manuals and undimensioned drawings. Attached is a cylinder drawing and two undimensioned drawings. A source is https://app.aircorpslibrary.com/aircraft/allison-v-1710 but it costs money.

Lohring Miller
cylinder.jpg
12 counterweight crankshaft.jpg
Allison9.jpg
 
Thanks for the info, I accidently stumbled across this site Friday that you referenced. May have to bite the bullet and become a member. I reached out to [email protected] for information today, (ie:manuals, detail drawings, tech bulletins, etc.).I'm hoping as a employee the trust will take a interest in the project and provide documentation. Thanks again.
 
is there some reason to not model the Rolls Royce ?

the Allison has a couple things going against it
1 - the head and cylinder block is one piece, the cylinder liners are inserted from below,
which is very problematic (yes Barry Hares modeled an early RR that had that problem,
as have several people modeling the Offenhauser, but I chose a later RR version that had a
traditional separate head and cylinder block, much more convenient to design and build)
2 - the valves are slanted, it can be done, I'm doing that for my Duesenberg, but might not
want to do it again, I made custom Vee Blocks but wasn't careful enough and didn't realize
how accurately they need to be made for repeatability in mounting the head to the milling vise.
3 - the best models had a turbocharger rather than supercharger, I've built a supercharger but
would not attempt a turbocharger (too hot, requires inconel, not machinable)

to be fair the RR has a couple things going against it too
1 - the "inclined shafts" intermediate drive shafts to the cam shafts, I redesigned them to be
at the same 60-deg as the cylinder banks themselves (that RR didn't do this is a sad story,
they were all too well aware of the problems their design had)
2 - the "wheel case" between the crankcase and supercharger is insanely complicated, I simplified
mine considerably, but being sandwiched between the crankcase and supercharger you cant
really notice.
3 - the version of the RR that was considered superior to the Allison had 2-stage supercharger and
an intercooler, no way was I going to model that much complexity (not even cosmetically, Ugh!)

so there you have it, your thoughts ?
 
I´m little bit buzzled about Allison cylinder block. Refering to Allison maintenance manual the cylinder barrels are shrunk to the head and aluminum coolant jacket is fitted to the head by studs. Cylinder barrels are secured at the bottom end to the coolant jacket by nuts. The block is then held to the crankcase by long stud thru the head. Is there something I didn´t catch.
 
Look carefully at the cylinder picture I posted.
From the Allison Manual:

Cylinder Banks-Each cylinder bank comprises
three basic parts: A one-piece cast aluminum alloy cylinder head, six individual steel cylinder
barrels, and a one-piece cast aluminum coolant jacket enclosing all six cylinder barrels. Each
bank of six cylinders is removed or installed individually as a complete unit.

Cylinder barrels are machined from nickel
molybdenuin (sic) forgings, carburize-hardened, with small ribs on the outer surface to aid
cooling. Barrels are shrunk fit to the cylinder head and enclosed by a coolant jacket. The coolant
jacket for each cylinder bank is a one-piece aluminum alloy casting, secured to the head by studs
located to insure maximum tightness of this joint.
Each cylinder barrel is sealed at the bottom of the coolant jacket by a steel washer and large .
circular nut threaded onto the barrel. In production, the circular nut is seated with 2,200 foot
pounds torque using a hydraulically operated machine.
Stainless steel sleeves around each barrel divide the coolant area into two sections. Coolant flows
freely in the turbulent section around the barrels, but coolant between the sleeve and jacket
remains somewhat stagnant and prevents 'cylinder barrel distortion ...........

Lohring Miller
 
Many unlimited hydroplane racers considered the Allison to be a stronger engine than the Merlin. With the addition of twin turbochargers it has been run against turbine powered boats. See

Lohring Miller
 

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Look carefully at the cylinder picture I posted.
From the Allison Manual:

Cylinder Banks-Each cylinder bank comprises
three basic parts: A one-piece cast aluminum alloy cylinder head, six individual steel cylinder
barrels, and a one-piece cast aluminum coolant jacket enclosing all six cylinder barrels. Each
bank of six cylinders is removed or installed individually as a complete unit.

[ ... ]

Lohring Miller

OK, I stand corrected, I do now see a parting line in fig 36 between head and block, I was only slightly mis-interpreting the drawing below fig 18 which does show studs going from the top of the head all the way into the crank case, but it doesn't show a parting line between the head and the block,

follow your dream, go for it (with dual turbo-chargers!) :) !!!
 
The smallest readily available turbochargers are the RHF series. At 1/4 scale each bank has around 54 cubic inches or .87 liters. Two RHF3 turbos at $300 to $500 each would be about the right size giving way more power than you need in a demonstration engine. I would use a dummy shroud over a carb for each bank. The good news is you wouldn't need to build the supercharger and its drive train. Just in case you're crazy the specs for the RHF turbos are below.

Lohring Miller
 

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The smallest readily available turbochargers are the RHF series. At 1/4 scale each bank has around 54 cubic inches or .87 liters. Two RHF3 turbos at $300 to $500 each would be about the right size giving way more power than you need in a demonstration engine. I would use a dummy shroud over a carb for each bank. The good news is you wouldn't need to build the supercharger and its drive train. Just in case you're crazy the specs for the RHF turbos are below.

Lohring Miller
at 5" diameter compressor and 5-1/4" diameter turbine these don't seem right for a quarter scale V12, in the photos of the hydroplane they are about as big in diameter as the valve covers are wide, but the rotors inside can't be more than about 1-1/2" (based on their max RPM) so maybe you could make your own smaller housings / scrolls to match the scale of your engine. IMHO, just a thought !
 
Got some great news from the heritage indy folks today. They let me know that the have probably have most of everything that I am looking for to scale down a v1710 allison. They are going to let me go through their archives and are willing to make copies of anything I deem useful. Hopefully in near future I will be scaling it down. Haven't decided yet if I would want to go 1/4 or 1/5 scale. I have a #13 Brown & Sharpe grinder that I am going to try convert to crank/cam grinder with fixtures, this will be the determining factor on scale because of center distance of headstock/tailstock with fixturing. The Hertitage Indy people seem interested in the project also. Thanks again to everyone who has giving me info or thoughts along the way. I'll post more when I have more.
 
congrats !!!

I just learned that the Allison is what powered the P38 Lightning designed by none other than Kelly "skunk works" Johnson, so its on the historically significant list for me !

I've seen Richard Maheu's Quarter Scale Merlin up close (we were somewhat acquainted back went he was making castings) and I have to say from my personal perspective its way to large, my own Merlin is 1:5.4 scale, so exactly 1" bore, and I'm very happy with it. but then you'll have to decide just how small you're willing to go for 4-valves-per-cylinder, mine are 5/16" and its pretty crowded in there, figuring out the geometry of valve placement and rocker arm angles was tricky !

Pete.
 

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