Here was a question I had are Rolls Royce Griffons more rare than the Merlins? Are parts harder to come by for them? And are there many people that know how to work on them and the gear box for the contra rotating propellers I was told they can be trouble. As far as Allisons go aside from Polar bear and the P40s that race in the Bronze and Silver class is there a reason why race teams wont use Allisons in Gold racers can't they be souped up just like a Merlin or is it just a availability issue. Thanks Mark.
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Re: Griffons and Allisons
Originally posted by MARK SHANE View PostHere was a question I had are Rolls Royce Griffons more rare than the Merlins? Are parts harder to come by for them? And are there many people that know how to work on them and the gear box for the contra rotating propellers I was told they can be trouble. As far as Allisons go aside from Polar bear and the P40s that race in the Bronze and Silver class is there a reason why race teams wont use Allisons in Gold racers can't they be souped up just like a Merlin or is it just a availability issue. Thanks Mark.
As for the Griffon, even though there weren't nearly as many produced, I'm sure there is still a bigger stash to pull from than what is left of the Merlin. And while Rolls Royce didn't make a worse engine with the Griffon, it came along at the beginning of the jet age and wasn't produced in the mass quantities as it's younger sibling.
The Shackelton prop setup isn't inherently "trouble"...no more than any other setup, except you have twice the fun to play with. If you lose oil pressure the blades to to flat pitch, the props overspeed, and it's like a huge six-blade boat anchor out on the nose. Airplane goes 400 knots to 50 knots in a real hurry. It's happened twice in the racing Mustangs, both resulting in crashes.
But the thing to remember is that the system (at least on the Shackelton version, not necessarily on the Spit/Seafires that used them) was designed to go out on a 12 hour mission and loiter around at 35 inches of manifold pressure all day long. In the racing Mustang, you're trying to stuff 100+ inches of mercury down it, and that oil/prop system is running WAY above what it's comfort zone is.
And anyone who saw Skip lose the prop governor in Jeannie back in '82 will testify that the same thing happened to the 4-blade Aeroproducts prop, so it's kind of unfair to tag the Shackelton counter-rotating system as trouble...as I said, it's no different than any other system that is running such huge manifold pressure and RPM's.
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Re: Griffons and Allisons
I think one of the biggest "problems" with the griffon is since there where so few aircraft using the contra-rotating set up, there is not a lot of props to choose from. I think, and I'm sure the experts here will correct me if i'm wrong, that the shackelton blades just are not the right airfoil and profile for racing. As big jim said, it was made to hang around all day at a low power setting. there is only so much re-profiling and re-pitching you can do to them.
I think that a lot of speed could be found on PM with a blade more optimized for racing, if such a prop could be found.bob burns
ex tow-3, now race 66 crew
"dont mess with texas"
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Re: Griffons and Allisons
Originally posted by JCP View Post"A Merlin in a box is faster than an Allison on a Mustang"
I believe what you meant to say was:
"You can fly an Allison farther than you can ship a Merlin"
JC
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Re: Griffons and Allisons
Originally posted by Bob View Postquick question. Can you use an electric pump to control the prop pitch? That may negate the increased oil pressure?
SA
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Re: Griffons and Allisons
Originally posted by Big_Jim View PostYeah, but JC, you're straddling the fence there....and perhaps I'll remind you that if you bring the Bee to Reno this year and see just how much faster it goes than the Parrothead.
JC
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MARK SHANE
Re: Griffons and Allisons
Originally posted by Big_Jim View PostI'm sure Sparrow will ultimately chime in here, but bottom line even though the Allison has more cubic inches and stronger rods, the bottom end and supercharger on the Merlin is much better. To quote a dear friend of mine "a Merlin in a box is faster than an Allison on a Mustang". That's why the Mouse Motor (aka Allison-rod Merlin) is the best of both worlds...you take the strong points of each and combine them together.
As for the Griffon, even though there weren't nearly as many produced, I'm sure there is still a bigger stash to pull from than what is left of the Merlin. And while Rolls Royce didn't make a worse engine with the Griffon, it came along at the beginning of the jet age and wasn't produced in the mass quantities as it's younger sibling.
The Shackelton prop setup isn't inherently "trouble"...no more than any other setup, except you have twice the fun to play with. If you lose oil pressure the blades to to flat pitch, the props overspeed, and it's like a huge six-blade boat anchor out on the nose. Airplane goes 400 knots to 50 knots in a real hurry. It's happened twice in the racing Mustangs, both resulting in crashes.
But the thing to remember is that the system (at least on the Shackelton version, not necessarily on the Spit/Seafires that used them) was designed to go out on a 12 hour mission and loiter around at 35 inches of manifold pressure all day long. In the racing Mustang, you're trying to stuff 100+ inches of mercury down it, and that oil/prop system is running WAY above what it's comfort zone is.
And anyone who saw Skip lose the prop governor in Jeannie back in '82 will testify that the same thing happened to the 4-blade Aeroproducts prop, so it's kind of unfair to tag the Shackelton counter-rotating system as trouble...as I said, it's no different than any other system that is running such huge manifold pressure and RPM's.
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Re: Griffons and Allisons
Originally posted by Matt58 View PostJCP, not trying to steal the thread here, but you put on one impressive performance today in the P-40! In fact, I was rather impressed with the enitre airshow. very nicely done!
Mark Peterson (Diamondback and Hell-Er-Bust) is the spark plug and driving force behind the re-vitalization of the Caldwell Show called "Celebration of Flight Idaho". He and his team really are working hard to put and build a first class Air Show.
JC
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Re: Griffons and Allisons
Originally posted by JCP View PostThanks Matt...we had lots-O-fun for sure!
Mark Peterson (Diamondback and Hell-Er-Bust) is the spark plug and driving force behind the re-vitalization of the Caldwell Show called "Celebration of Flight Idaho". He and his team really are working hard to put and build a first class Air Show.
JC"CHARLIE DON'T SURF!!!"
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Re: Griffons and Allisons
Heading back on topic.. the late production seafires the Mk 46/47 used a contra-prop setup infront of griffon 81 or 85 series, but with only a 115 odd airframes produced and with 185 shackletons which used the 50 series griffons, there are a lot less with contra setups but there were a lot of fairy fireflies, spitfires and earlier mk seafires there were a lot of other griffons out there that used either 4 or 5 blade props, but again there are less around than the total of merlins built.race fan, photographer with more cameras than a camera store
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