A.A. Griffith and Whittle
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A.A. Griffith and Whittle
Looking around for stuff about German knowledge of British turbine developments, I've come across references to the review of Whittle's project for a jet engine by A.A. Griffith. As commonly, Griffith is depicted as foolishly obstructive.
The grounds I've seen for Griffith's objections were that axial compressors were superior to centrifugal, that a turbine driving a propeller was more efficient than a turbo-jet, that Whittle's device needed metals that did not exist, and by the way, there's an error in the maths.
Sometimes Griffith is described as "a civil servant", as though that clinched his imbecility.
In fact he did important work on metallurgy, especially metal fatigue; pointed out the importance of designing turbine blades as airfoils; and was hired by Rolls Royce in 1939. So not a clown. On axial compressors, he was right ultimately, though centrifugal compressors were easier to reach as a first stage as they could use supercharger design principles. He was wrong on the turbo-jet, though understandably so since at aircraft speeds of 1930 (and indeed at the speeds of 1945) the turbo-prop was (and remains) more efficient. The metallurgy was extremely challenging, and the chief problem for German jets, so not something that could have been guaranteed to be fixable in 1930.
Which looks like the sort of things a competent professional could well get wrong by misjudging the rate of change of technology (and especially not counting on the accelerated pace of development caused by WW 2). And if someone sends in a paper on a radical new technology with an error in the calculations, it's not unfair to point that out, is it?
So it looks to me like another example of the way in which British aircraft development is so often turned into a Stirring Tale of Heroes and Villains, designed to encourage stalwart lads in the service of the Empire. But I don't know the primary sources about the incident. Can anyone enlighten me on whether Griffith really was being unjustly obstructive, or whether it was just a case of competent engineers having a professional disagreement?
The grounds I've seen for Griffith's objections were that axial compressors were superior to centrifugal, that a turbine driving a propeller was more efficient than a turbo-jet, that Whittle's device needed metals that did not exist, and by the way, there's an error in the maths.
Sometimes Griffith is described as "a civil servant", as though that clinched his imbecility.
In fact he did important work on metallurgy, especially metal fatigue; pointed out the importance of designing turbine blades as airfoils; and was hired by Rolls Royce in 1939. So not a clown. On axial compressors, he was right ultimately, though centrifugal compressors were easier to reach as a first stage as they could use supercharger design principles. He was wrong on the turbo-jet, though understandably so since at aircraft speeds of 1930 (and indeed at the speeds of 1945) the turbo-prop was (and remains) more efficient. The metallurgy was extremely challenging, and the chief problem for German jets, so not something that could have been guaranteed to be fixable in 1930.
Which looks like the sort of things a competent professional could well get wrong by misjudging the rate of change of technology (and especially not counting on the accelerated pace of development caused by WW 2). And if someone sends in a paper on a radical new technology with an error in the calculations, it's not unfair to point that out, is it?
So it looks to me like another example of the way in which British aircraft development is so often turned into a Stirring Tale of Heroes and Villains, designed to encourage stalwart lads in the service of the Empire. But I don't know the primary sources about the incident. Can anyone enlighten me on whether Griffith really was being unjustly obstructive, or whether it was just a case of competent engineers having a professional disagreement?
Last edited by FlightlessParrot; 19th Jul 2021 at 01:15. Reason: Typo
Stirred memories of what was, possibly, an early 'scam'.
I was running Transmitter control at a model aircraft meeting at Abingdon and a chap came up and said he had some interesting information. The meeting was the first 'public' demo of Gerry Jackman's (world's first) model gas turbine, so ,presumably relevant. Anyway, this character said he had a collection of manuscript notes of Whittle's early experiments which he had retrieved from a rubbish bin in Oxford, and could someone advise him as to what best to do with them. From memory, I pointed him to one of the more knowledgeable flyers and heard no more,
Likely authentic documents, or a try-on? Irrelevant at this remove, but I wonder.
I was running Transmitter control at a model aircraft meeting at Abingdon and a chap came up and said he had some interesting information. The meeting was the first 'public' demo of Gerry Jackman's (world's first) model gas turbine, so ,presumably relevant. Anyway, this character said he had a collection of manuscript notes of Whittle's early experiments which he had retrieved from a rubbish bin in Oxford, and could someone advise him as to what best to do with them. From memory, I pointed him to one of the more knowledgeable flyers and heard no more,
Likely authentic documents, or a try-on? Irrelevant at this remove, but I wonder.
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Stirred memories of what was, possibly, an early 'scam'.
I was running Transmitter control at a model aircraft meeting at Abingdon and a chap came up and said he had some interesting information. The meeting was the first 'public' demo of Gerry Jackman's (world's first) model gas turbine, so ,presumably relevant. Anyway, this character said he had a collection of manuscript notes of Whittle's early experiments which he had retrieved from a rubbish bin in Oxford, and could someone advise him as to what best to do with them. From memory, I pointed him to one of the more knowledgeable flyers and heard no more,
Likely authentic documents, or a try-on? Irrelevant at this remove, but I wonder.
I was running Transmitter control at a model aircraft meeting at Abingdon and a chap came up and said he had some interesting information. The meeting was the first 'public' demo of Gerry Jackman's (world's first) model gas turbine, so ,presumably relevant. Anyway, this character said he had a collection of manuscript notes of Whittle's early experiments which he had retrieved from a rubbish bin in Oxford, and could someone advise him as to what best to do with them. From memory, I pointed him to one of the more knowledgeable flyers and heard no more,
Likely authentic documents, or a try-on? Irrelevant at this remove, but I wonder.
BTW, I remember, I think from Not Much of an Engineer, that Hooker was shown the design of Whittle's centrifugal compressor and suggested no improvements. Since Hooker built his reputation on designing the impeller for the Merlin supercharger, I take it that that's evidence that Whittle's design was really, really good.
Hooker did not design the Merlin supercharger, as is clear in the book that you quote. However, he did improve it hugely, leading to much higher power output from the engine.
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Not that it matters and I was quoting from memory but I said he designed the impeller of the supercharger; as I recollect, he applied stuff he had learned in his degree. If you would prefer, he improved the design of the impeller of the supercharger.
FP:
The Merlin had been running for some years before Hooker arrived at R-R in Derby, so the initial impeller design was not his. What he did was initially to improve the airflow through it, as in the Merlin XX and 45, then later introduced the 2-stage supercharger that raised engine power further. There's no need to take umbrage - but I do think it's worth being accurate. It's all in his book, in front of me now.
Regards,
KP
The Merlin had been running for some years before Hooker arrived at R-R in Derby, so the initial impeller design was not his. What he did was initially to improve the airflow through it, as in the Merlin XX and 45, then later introduced the 2-stage supercharger that raised engine power further. There's no need to take umbrage - but I do think it's worth being accurate. It's all in his book, in front of me now.
Regards,
KP
Last edited by kenparry; 19th Jul 2021 at 14:01. Reason: typo
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FP:
The Merlin had been running for some years before Hooker arrived at R-R in Derby, so the initial impeller design was not his. What he did was initially to improve the airflow through it, as in the Merlin XX and 45, then later introduced the 2-stage supercharger that raised engine power further. There's no need to take umbrage - but I do think it's worth being accurate. It's all in his book, in front of me now.
Regards,
KP
The Merlin had been running for some years before Hooker arrived at R-R in Derby, so the initial impeller design was not his. What he did was initially to improve the airflow through it, as in the Merlin XX and 45, then later introduced the 2-stage supercharger that raised engine power further. There's no need to take umbrage - but I do think it's worth being accurate. It's all in his book, in front of me now.
Regards,
KP
First, if you're going to be a stickler for accuracy, be accurate in quoting the post in front of you. You corrected me for saying that Hooker designed the supercharger, but clearly I did not say that. So you lose one pedant point.
Second. The impeller Hooker found was not the impeller with which the Merlin went on to be a success. The Merlin impeller that led to the engine's great success was Hooker's impeller. When we say "Merlin" we do not think of trials and development engines, but the long series of production engines: the engines with Hooker's impeller. Hooker did not design the initial impeller of the Merlin, but he did design the impeller in its final form.
This is entirely trivial and just what you find on internet forums (you're probably going to tell me I should say "fora"), but I am actually seriously interested in Whittle and Griffith and I don't want this think hi-jacked. But of course I'm hijacking it myself because I'm rising to your trolling.
Have a lovely day.
The impeller was only one part of Hooker's improvement. At least as important was his new supercharger intake design, in fact until you two started going on about it I'd forgotten that he modified the impeller as well.
Hookers 'subject' was airflow without the worry of the mechanics that had to go with it to keep it reliable. He could see that an improvement was possible but also had the 'maths' to prove it. His book gives a very fair view of the situation 'at the time' and the difficulties of all the companies having to ramp up production due to war time requirements. The original Whittle principle certainly worked well up to the Korean war period as the Mig15 proved. The Germans knew what was needed for future performance but of course they produced them for the wrong war.
Both Stanley Hookers and Rod Banks books are a great introduction to that 'interesting time' when someone had to decide on the limit that 4 stroke motors had with relation to a power/size/reliability limit, and any look at a sectioned Centaurus or Sabre (and associated gear train) leaves one in no doubt as to how complex they had become.
Remembering that the supercharger complexity had also grown accordingly and was as challenging as the engines themselves.
Both Stanley Hookers and Rod Banks books are a great introduction to that 'interesting time' when someone had to decide on the limit that 4 stroke motors had with relation to a power/size/reliability limit, and any look at a sectioned Centaurus or Sabre (and associated gear train) leaves one in no doubt as to how complex they had become.
Remembering that the supercharger complexity had also grown accordingly and was as challenging as the engines themselves.
The supercharger Hooker designed included the innovation of camber (called circular arc inducers) introduced on the leading edge of the impeller, plus he reduced the height of the impeller by approx 20% which had the effect of increasing the velocity of the air in the outwards direction near the edge of the impeller. He thought air entering the supercharger was being restricted due to its casing shape, which had been done to reduce engine length, Hooker thought it an undue compromise so redesigned the 90° intake elbow to give a smoother transition and turned the carburetor 180° without increasing engine length unduly. The angle of the diffuser vanes were altered to better match the air flow thrown off the tip of the spinning impeller, plus the gear ratio to give the desired impeller tip speed. The changes introduced are sufficient for me to call it designed by Hooker, after all, supercharger principle is fairly basic, it's the detail that sets one apart from the other.
Quite possible given a reading of wiki and Rolls Royce item.
https://en.wikipedia.org/wiki/Alan_Arnold_Griffith
Rolls Royce article,
https://web.archive.org/web/20070927...iew.jsp?id=116
ust a case of competent engineers having a professional disagreement?
https://en.wikipedia.org/wiki/Alan_Arnold_Griffith
Rolls Royce article,
Strangely, Griffith did not propose the turbojet engine and was unsupportive of Frank Whittle, describing his assumptions as over-optimistic and finding fault with his calculations. Some have accused Griffith of lack of intellectual honesty and while it may be true that Griffith’s response delayed the development of the gas turbine, his reason was almost certainly due to his pursuit of perfectionist solutions.
