A definite 'yes', the V-1650-1 in Mustang would've made for an excellent aircraft for 1942/43.
What was the problem with the allison engine? (3 Viewers)
- Thread starter davparlr
- Start date
A definite 'yes', the V-1650-1 in Mustang would've made for an excellent aircraft for 1942/43.
On pg.332, Dan Whitney quoted USAAF statistics which shows that the Packard Merlin finished dead last in reliability, with the shortest engine life and highest maintenance hours between overhauls as compared to the Allison V-1710 and Pratt Whitney R-2800.
Do you have numbers to validate this, or are you just floating the idea?
Comparing peacetime restrictions with wartime restrictions offers no proof that Rolls Royce Merlins were less troublesome.
Single piece Merlin cylinder blocks cracked and leaked from high boost pressures and so did two piece engine blocks intended to correct that problem. Wartime experience also showed weaknesses in connecting rods, main bearings, pistons, valves, lubrication points, supercharger drives, magneto gears, and of course carburettors.
Failures of the supercharger clutch and friction plates gave ongoing problems that continued into the Griffon series. In 1946, all deck-landings of the Seafire Mk XV were prohibited until Rolls Royce re-designed the supercharger unit.
High dust conditions caused the failure of many Rolls Royce engines. Ginger Neil of No. 249 Squadron said that he went through five engines in eight weeks on Malta, even though the Merlins were "almost brand new".
My sources show that at 30,000 feet, the output of all three engines is approximately 700 b.h.p. More importantly, Allison could not build the V-1710-81 until the customer asked for it. Buyers dictate requirements to the engine maker, not the other way round as your reply suggests.
Alec Harvey-Bailey worked at Rolls Royce and his definition (p.14) does not agree with yours …
" The Merlin came to the forefront in the air fighting during the Dunkirk period and subsequently during the Battle of Britain. The engines which carried the brunt of the fighting were basic single stage supercharged types, notably the Mk II and III although some Merlin XIIs in Spitfire IIs with higher geared superchargers."
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No problems with that, there was no perfect engines.
I've provided the sources for my nubers that everybody can check out and call me fishy if it's not true.
As above - no engine was perfect. The V-1710 received new crankshaft (several times), new reduction gear, new piston rings, new intake manifold (again several times), supercharger drives, carburetors, all in the trying to improve both reliabilty and power.
BTW, the Merlin III was rated for +12 lbs boost (1300 HP) before the war.
Should we now compare the Griffon with V-1710?
Without dust filters. every engine will fail in dusty conditions.
The V-1710-81, Merlin xx and 45 will still give more at 30000 ft. Thing being that -81 is two years late vs. the Merlin XX and year and a half vs. Merlin 45.
The Allison'sr 1st attempt for increased supercharger gearing (on F14R engine) was unsucessful, per pg. 272 of the Vee's. The F20R (V-1710-81) received wider (hence stronger) drive gears, thus solving the problem.
My reply didn't suggest that Allison was incapable of coming out with a better performing engine, the US Army squandered plenty of money on the 'hi-per' engines instead funding the V-1710. Power of the V-1710 grew with each year. The thing is that it was a year and a half (give or take few months) behind the Merlin's altitude power levels, when we talk about single- and two-stage engines.
I think that you have misunderstood what Mr. Haryey-Bailey said. The Merlin III was 'geared' at 8.58:1, the XII and 45 were at 9.089:1, less that 5% difference. Both were 'high' geared (same as the V-1710 was 'high' geared whether it employed 8.77:1, 8.8:1 or 9.6:1). Having a gearing that is less than 5% 'faster' does not mean that other gearing is suddenly 'low'. Stating gearing without taking into account the supercharger diamenter is pointless.
For 'low' geared superchargers, please look at Merlin VIII (on Fulmar) and V-1710-87 (F21R, on A-36).
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And yet thousands of Packard Merlins were used on P-51B/C/D/K's, Mosquitoes and Lancasters that all flew thousands of long range operations totaling hundreds of thousands of hours. The fact is all three engines were reliable enough for the purpose for which they were built - namely wartime service, often under extremely adverse conditions.
While EKB later quotes from Alec Harvey-Bailey's The Merlin in Perspective: The Wartime Years, EKB failed to quote from Harvey-Bailey when H-B explained how Rolls-Royce's continual testing and development overcame the problems that he describes (eg: pages 57, 58 66):
I suggest that EKB read and digest the entirety of Harvey-Bailey's book, especially pages 31 to 71, before he makes sweeping generalizations about the supposed ongoing "weaknesses in connecting rods, main bearings, pistons, valves, lubrication points, supercharger drives, magneto gears, and of course carburettors." The implication that the Merlin suffered from a large number of ongoing design problems and constant component failure is grossly wrong.
Evidence for this would be great.
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GregP
Major
You all know I worked in an Allison overhaul shop for a few years. I love the Allison. We liked to joke that you could fly an Allison farther than you can ship a Merlin.
But the fact remains that the Merlin was and IS a very good engine. Yes, Merlin rods are weaker than Allison rods ... but they don't give up the ghost until somewhat over 2,600 HP, which is more than the engine produced in normal WWII military trim. There are a number of things I don't particularly like about the Merlin, but I'd own either own if I could, and I would expected to get 750 - 1000 hours of use out it before overhaul in civilian service. At the Planes of Fame, we just changed a Merlin in one our P-51D models, and it had a very long and trouble-free lifespan during that time. Yes, you DO have to tighten the head bolts every 25 hours and so forth, but there are normal regular maintenance requirements for any large aviation piston engine.
So despite being a lover of Allisons, I have to say the Merlin earned it's stripes and then some, and richly deserves it's place as one of the great aero engines of all time. Rolls Royce didn't design a perfect engine and neither did Allison, but Rolls also didn't miss by all that much.
The Merlin DID have a shorter overhaul life than the Allison. But overhaul was NOT when the engine broke or wore out. It was when the military decided to swap it for a fresh engine and send the "run out" engine in for an overhaul while it was still in good overhaulable shape. These days, all owners want their pet Allison or Merlin to get 750 - 1000 hours before overhaul, and they mostly DO, assuming a good overhaul. I know many people who are flying Merlins right now with 400 - 700 hours on them and they are running just fine.
If only we had an ongoing parts supply!
But the fact remains that the Merlin was and IS a very good engine. Yes, Merlin rods are weaker than Allison rods ... but they don't give up the ghost until somewhat over 2,600 HP, which is more than the engine produced in normal WWII military trim. There are a number of things I don't particularly like about the Merlin, but I'd own either own if I could, and I would expected to get 750 - 1000 hours of use out it before overhaul in civilian service. At the Planes of Fame, we just changed a Merlin in one our P-51D models, and it had a very long and trouble-free lifespan during that time. Yes, you DO have to tighten the head bolts every 25 hours and so forth, but there are normal regular maintenance requirements for any large aviation piston engine.
So despite being a lover of Allisons, I have to say the Merlin earned it's stripes and then some, and richly deserves it's place as one of the great aero engines of all time. Rolls Royce didn't design a perfect engine and neither did Allison, but Rolls also didn't miss by all that much.
The Merlin DID have a shorter overhaul life than the Allison. But overhaul was NOT when the engine broke or wore out. It was when the military decided to swap it for a fresh engine and send the "run out" engine in for an overhaul while it was still in good overhaulable shape. These days, all owners want their pet Allison or Merlin to get 750 - 1000 hours before overhaul, and they mostly DO, assuming a good overhaul. I know many people who are flying Merlins right now with 400 - 700 hours on them and they are running just fine.
If only we had an ongoing parts supply!
Commander Mike Crosley, DSC:
" The second lethal shortcoming of the Seafire XV was a supercharger fault. The self-change mechanism from one blower speed to the higher speed was similar in action to the automatic clutch and gearbox of a car. When changing blower speeds on the climb, the blower speed of about 15,000 rpm had to be speeded up to 20,000 rpm in a matter of seconds. If the clutch gripped too tightly it would strip the gears. If it gripped too loosely it would burn out. In both failures the engine would lose its supercharger and it would stop, catch fire, misfire or overheat. The only method of avoiding such failures was the engage the gear manually at reduced rpm. This was not always possible, neither did it always work, for there were several fatal engine failures."
R. M. Crosley. They Gave Me a Seafire. Airlife Books, 1986 (See Appendix 11).
I did not write that. If you have statistics regarding component failures (to back up your opinions) then by all means post it.
Please refer to attached chart for engine life and maintenance hour averages for Packard Merlin (V-1650) and other U.S. engines ...
Attachments
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fastmongrel
1st Sergeant
Its a pity the Merlin V1650 was so rubbish. Just think over 150,000 lumps of junk were built over about 12 years and those idiots didnt know they were doing it wrong.
Especially as they put them in that pile of shite, one trick pony the spitfire !
Airframes
Benevolens Magister
There was a problem with both the Rolls Royce, and Packard Merlin. One didn't have 'Made in the USA' (or Germany!) stamped on it, and the other one did !!
And how does this prove that the Merlin suffered from
So, why did EKB write this:
if not to imply that the Merlin continually suffered from these problems? Otherwise what was the point of writing it?
Considering that the Merlin was being continually developed from a 1,000 hp engine to one able to produce 2,000 hp, it's no wonder that problems would emerge; it's the fact that the problems were solved that's important.
Yes...and?
So few words that say so much...
From your latest reply, it's obvious that you have no idea how many engines suffered "component failures". Despite your lack of knowing the numbers, you continue to raise and argue that point, for reasons that only you can answer.
If you are so sure of your convictions, maybe you can explain why Rolls Royce would switch to two piece engine block if there were no serious problems with the single piece engine block.
If troubles with the supercharger mechanisms were (supposedly) fixed and perfected with the Merlin, maybe you can give us your take on why these issues lingered with the Griffon engine - and this after World War II ended.
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FLYBOYJ
"THE GREAT GAZOO"
I've been reading this with some amusement, but for the record I don't have a dog in this fight but I will say you need to show all the charts indicated in your post and keep in mind that this is a CONUS chart and at face value doesn't represent combat conditions. It should also be compared with the number of airframes those engines are "attached" to and the hours those airframes are flown as a fleet.
My 2 cents - the stock market looks good!
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EKB raised the whole "Merlin is so-o-o unreliable vs the Allison" schtick; it's up to EKB to support his own convictions with more than just meaningless, bald statements. In the meantime I suggest EKB read Harvey-Bailey carefully to find out for himself how Rolls-Royce resolved various component failures.I suggest EKB read Harvey-Bailey, pages 55-56 to find out.
I suggest EKB read Harvey-Bailey, pages 40-45 to find out. The isolated troubles of the Griffon on some Seafires have nothing to do with the Allison V-1710.
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GregP
Major
Just for completeness, here are the data from Table 115 for the Statistical Journal of the USAAF:
These are, as Joe said above, all Continental USA numbers and are somewhat unrelated to engines being operated on the front lines. I'd expect front-line engines to be overhauled either slightly sooner or about the same time since any Merlin or Allison that was running at overhaul hours was running pretty decently. If the engine was being operated on, say, Malta, where Coral dust was so prevalent, it wouldn't make TBO and would be overhaul based on condition rather than overhaul hours.
The Merlins were great engines for high-altitude, long-range flying,and the Allison was developed into one, but wasn't quite there when it was needed. Right when Allison started building the G-series engine and they really made decent power, they started cancelling pistons for jets, and Allison never did get the G-series engines as reliable as earlier Allisons were. For my money a -100 series E-series or F-series engine was the best Allison for the money.
As for the Merlin, it was there, could do the job well if not superbly, was reliable in service, and usually lasted some 35 - 50 mission before needing to be swapped out. That isn't all that bad. Many Merlins were found to be "in spec" when received for overhaul, and the "overhaul" consisted mostly of new bearings, perhaps a valve or two, cleanup of parts, and possibly new supercharger impellers, with possibly a gear or two, depending on inspection. Rods were probably changed on the second or third overhaul regardless of condition. I seriously doubt they wore out many cams or crankshafts. They are stout units. Typical of British engines, they gave some serious attention to ignition systems at overhaul.
But in service, the Merlins were as reliable as any aero engine of the day, and moreso than some.
I can say this. I've worked 8 Planes of Fame airshows. We usually have 30 - 35 WWII aircraft there with a mixed bag of Allisons, Merlins, Wrights, Prats, and a smattering of others. The planes fly for 3 days with about 50 - 65 sorties per day. That's 1200 - 1400 sorties in my airshow years there. We've had maybe 5 - 6 mission aborts in that time with one being a flat tire, one being hydraulic-related (A Corsair could get the wings to come down), and 2 of the aborts were radials. That leaves 1 or 2 aborts for the V-12s, and, as I recall, a P-51D had a run-down battery on one, and the other was a Curtiss-Electric prop on a P-40E that needed brushes.
In my book, that ain't bad considering we have probably about half Merlins there in a typical year.
Above, I'm calling an "abort" a plane that is scheduled to take off and the pilot goes out to it to fly the show and then discovers something wrong. There were a few others that never tried to fly because something was discovered before the scheduled flight. Most of those are not engine-related.
We did have one B-17 have an emergency in flight when he hit a BIG bird. The damage was a hole in the leading edge inboard of the #1 engine, and was not engine-related. He landed safely and flew home on schedule. Who knew a bird had that much blood or that many feathers?
By the way. The Merlin was done in typical British craftsman fashion and the Allison was optimized for production. Consequently the Allison has about 7,000 parts including nuts and bolts and the Merlin has about 11,000 parts. A significant amount of the Merlin labor is dealing with another 2,000+ fasteners, many with pal-nuts! The actual overhaul labor is very similar, but taking a Merlin apart and putting one back together again means handling probably 5,000 more fasteners than for an Allison (apart and back together, both tasks). These are aircraft nuts and don't "spin" off by hand. You use a wrench all the way (no, not a ratchet wrench!), and that takes awhile.
For clarity, it is not really 2,500 more fasteners, it is 2,500 more parts. A fastener was a bolt, a washer, a nut and pal nut or a bolt, a washer, a lock washer, and a nut ... depending on application. Sometimes there were two washers. Then there is the safety wire and/or cotter pins to consider. None are hard to work with, but all take time to place and tighten to spec.
These are, as Joe said above, all Continental USA numbers and are somewhat unrelated to engines being operated on the front lines. I'd expect front-line engines to be overhauled either slightly sooner or about the same time since any Merlin or Allison that was running at overhaul hours was running pretty decently. If the engine was being operated on, say, Malta, where Coral dust was so prevalent, it wouldn't make TBO and would be overhaul based on condition rather than overhaul hours.
The Merlins were great engines for high-altitude, long-range flying,and the Allison was developed into one, but wasn't quite there when it was needed. Right when Allison started building the G-series engine and they really made decent power, they started cancelling pistons for jets, and Allison never did get the G-series engines as reliable as earlier Allisons were. For my money a -100 series E-series or F-series engine was the best Allison for the money.
As for the Merlin, it was there, could do the job well if not superbly, was reliable in service, and usually lasted some 35 - 50 mission before needing to be swapped out. That isn't all that bad. Many Merlins were found to be "in spec" when received for overhaul, and the "overhaul" consisted mostly of new bearings, perhaps a valve or two, cleanup of parts, and possibly new supercharger impellers, with possibly a gear or two, depending on inspection. Rods were probably changed on the second or third overhaul regardless of condition. I seriously doubt they wore out many cams or crankshafts. They are stout units. Typical of British engines, they gave some serious attention to ignition systems at overhaul.
But in service, the Merlins were as reliable as any aero engine of the day, and moreso than some.
I can say this. I've worked 8 Planes of Fame airshows. We usually have 30 - 35 WWII aircraft there with a mixed bag of Allisons, Merlins, Wrights, Prats, and a smattering of others. The planes fly for 3 days with about 50 - 65 sorties per day. That's 1200 - 1400 sorties in my airshow years there. We've had maybe 5 - 6 mission aborts in that time with one being a flat tire, one being hydraulic-related (A Corsair could get the wings to come down), and 2 of the aborts were radials. That leaves 1 or 2 aborts for the V-12s, and, as I recall, a P-51D had a run-down battery on one, and the other was a Curtiss-Electric prop on a P-40E that needed brushes.
In my book, that ain't bad considering we have probably about half Merlins there in a typical year.
Above, I'm calling an "abort" a plane that is scheduled to take off and the pilot goes out to it to fly the show and then discovers something wrong. There were a few others that never tried to fly because something was discovered before the scheduled flight. Most of those are not engine-related.
We did have one B-17 have an emergency in flight when he hit a BIG bird. The damage was a hole in the leading edge inboard of the #1 engine, and was not engine-related. He landed safely and flew home on schedule. Who knew a bird had that much blood or that many feathers?
By the way. The Merlin was done in typical British craftsman fashion and the Allison was optimized for production. Consequently the Allison has about 7,000 parts including nuts and bolts and the Merlin has about 11,000 parts. A significant amount of the Merlin labor is dealing with another 2,000+ fasteners, many with pal-nuts! The actual overhaul labor is very similar, but taking a Merlin apart and putting one back together again means handling probably 5,000 more fasteners than for an Allison (apart and back together, both tasks). These are aircraft nuts and don't "spin" off by hand. You use a wrench all the way (no, not a ratchet wrench!), and that takes awhile.
For clarity, it is not really 2,500 more fasteners, it is 2,500 more parts. A fastener was a bolt, a washer, a nut and pal nut or a bolt, a washer, a lock washer, and a nut ... depending on application. Sometimes there were two washers. Then there is the safety wire and/or cotter pins to consider. None are hard to work with, but all take time to place and tighten to spec.
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FLYBOYJ
"THE GREAT GAZOO"
See post 257
