could the Allison engine have done what the Rolls Royce Merlin did?

[tomo pauk]

Agreed. The point that I was making is that NACA was working on the V-1710 through most of the war.

They probably did. Again, unfortunately, the effects of whatever the improvements they whipped up for the V-1710 seem to be very, very elusive until too late. If someone can correct me on this I'd be very grateful.

However, when I read your first quote, I don't think they are actually taking credit for turbocharging the B-17. It certainly wasn't considered to be obsolete.

Agreed on the 2nd sentence there, too bad PPD disagrees (disagreed).

Here is a more nuanced description of NACA involvement from NASA - WWII & NACA: US Aviation Research Helped Speed Victory

"Engine research did not receive very much public attention. One project NACA engineers often high-lighted was their work on the engines for the Boeing B-17 Flying Fortress. While testing the early B-17 prototypes, the Army had discovered that adding a turbo-supercharger would greatly improve the altitude and speed of the bomber. The Army ordered future B-17s be equipped with turbo-superchargers.

Army didn't 'discovered' that adding a turbo would greatly improve things while testing the early B-17 prototypes, they knew it will, since they were championing the research wrt. turbocharging through 1930s, and were using aircraft with turboed engine(s) in 1930s.
Engine on the B-17 is one thing, addition of turbo is another thing.

Supercharger technology was not very well developed and Wright Aeronautical, makers of the R-1820 Cyclone engines used on the B-17, struggled with the requirements. This was precisely the kind of problem the engine lab was intended to work on. Eventually, the turbo-supercharger problems were resolved and the B-17, a true high-altitude, high speed bomber, went on to become one of the military's most successful bombers. The turbosupercharger was also used with great success in the Boeing B-29 Superfortress. The Wright R-3350 Duplex Cyclone that powered the B-29 also underwent extensive testing in the NACA's new Altitude Wind Tunnel at the engine lab."

One is left to question of just how the under-staffed PPD was able to solve the addition of turbochargers for B-17s already in 1939. Also - was the solution of supercharger problems just due to the work of PPD, or someone else sould be mentioned, perhaps the company making B-17s, and/or company making turboes?

To be fair to NACA they did a lot of research into superchargers and turbochargers in the inter war period. I have attached a NACA paper as an example.

They certainly did.
I've read a lot of NACA reports, just like a lot of other enthusiasts. Problem is when someone muddles the water for no particular reason, bar to paint the (any) institution in the best light possible. Nobody was twisting the arms of the writer to claim the things he claimed in the article quoted before.
A writer has test report(s) that prove that V-1710 was with 'basic flaws' making any improvement a waste of resources? Point out to the test reports, or don't mention that at all if there is no proof.

The second quote certainly does try to take credit for the improved Spitfire exhaust stacks. NACA did test exhausts on a Spitfire V, but I am sure that Rolls Royce had done their own research into Merlin exhaust systems. I have attached a copy of the report

Thank you.
I guess both you any I know that a major performance jump for the Spitfires and Mustangs came from installation of ever-better engines after all.

 

[GregP]

The first statement doesn't stand up to close scrutiny, no Allison ever matched the performance of a 100 series Merlin. There is no evidence that the Army stopped Allison from working on 2 stage supercharging. Allison were building test models in 1942. The problem is that Allison didn't think about actually fittingly it into existing aircraft. This is in stark constrast to Rolls Royce who designed a very compact 2 stage arrangement for the Merlin and extensively redesigned the Griffon to allow it to fit into Merlin engined aircraft.

Early Allisons were every bit the horsepower of early Merlins. Both were just over 1,000 hp. The early nose case wasn't the best design but, by the time the E and F series Allison came out, they were fine. It took Sir Stanley Hooker's efforts to make the 60-series and later Merlins with his compact 2-stage supercharger. The late Allisons were pretty good at 1,600 hp WER. . The aux-stage units made very good HP.

There is PLENTY of evidence the government rejected Allison's desire to develop a 2-stage unit. All you have to do is go look for it. The auxiliary-stage they came up with was funded in-house.

Allison produced what the government ordered. Had the government funded development, Allison could have done it, and that is what you get when your engine design is funded and owned by the government. Initial development was funded by and owned by the U.S. Navy as a dirigible engine. Later developments came about with Navy and Air Corps funding. Allison didn't have Rolls-Royce's pocketbooks and most of the early days were consumed with trying to build enough infrastructure to satisfy the orders coming in rather than performance development.

The Merlin was and IS a great engine, especially later (60-series and later), if you needed to fly high. But a properly worked out turbo system was as good as a 2-stage supercharger. A Lockheed P-387L, with a good turbo system had a service ceiling of 44,000 feet. The last Merlin Spitfire, the Mk IX, had a service ceiling of 42,500 feet. The P-38L was also faster than the Spitfire IX. So, saying the Allisons never matched up isn't exactly looking at all the facts.

Personally, I think the Merlin was better suited to the ETO's higher-altitude operations because turbo systems were complex by comparison to supercharger systems and required special metals to handle the heat. Allison development generally lagged Merlin development due to Rolls-Royce being able to do what they pleased while Allison was dependent on government funding for any development. That being said, an Allison held a tune longer, had a longer TBO in general, and was more rugged, but the Merlin was a great performer and served with distinction. The TBOs were set not by how the engine ran or by age, but by the desire for 99% of all engine blocks being sent in for rebuild to actually BE rebuildable.

I'd say the Merlin was gem but there was nothing wrong with an Allison, assuming you were fighting in the Allison's altitude band, after the few issue were worked out. That was late 1942 early 1943. The issue came if you needed to fight up high. In that case, you needed the turbo or the auxiliary-stage supercharger, which the P-39 and P-40 didn't get. So, you were left with the P-38 as your choice. The P-63 was very good in the mid 20,000 foot area, but didn't have the range to be generally useful, so it never got procured by the USAAF. The Soviets loved it since they had use for a shorter-range interceptor.

Look at the top 10 U.S. aces. Collectively they shot down 323.83 enemy aircraft. About 8 were in P-40s; 27 in P-51s; 34 in F6Fs; 45 in F4Us; 50 in F4Fs; 55 in P-47s; and 105 in P-38s. You might see that the P-38 (Allison power) shot down about twice the percent of any of the other top 10 ace mounts. Perhaps dismissing the Allison is disingenuous?

 

[FLYBOYJ]

There is no evidence that the Army stopped Allison from working on 2 stage supercharging. Allison were building test models in 1942. The problem is that Allison didn't think about actually fittingly it into existing aircraft.

Allison produced what the government ordered. Had the government funded development, Allison could have done it, and that is what you get when your engine design is funded and owned by the government.

Greg hits this nail on the head and many folks don't realize, forget or simply refuse to understand that manufacturers very rarely go into projects unfunded and/or unsolicited!!!!

 

[pbehn]

Greg hits this nail on the head and many folks don't realize, forget or simply refuse to understand that manufacturers very rarely go into projects unfunded and/or unsolicited!!!!

The two stage Merlin started as a government request for a high altitude Wellington bomber. RR may have had ideas about what could be done and discussed them but the finance for such a project comes from others, usually a government.

 

[FLYBOYJ]

The two stage Merlin started as a government request for a high altitude Wellington bomber. RR may have had ideas about what could be done and discussed them but the finance for such a project comes from others, usually a government.

Exactly.

We've discussed this before - there have private ventures that were eventually bought by "a government," but those are more the exception than the rule. "No one does something for nothing."

 

[Shortround6]

"No one does something for nothing."

Allison especially and for very good reason.

In the spring/summer of 1939 the government owed Allison over 900,000 dollars for work already done.

It order to accept overseas orders Allison had to "forgive" (write off) the dept.

If Allison had not gotten the contract for the P-40 engines in April of 1939 there is a good chance GM would have shut down the engine division and kept the bearing division.
GM had loaned Allison about 500,000 dollars to keep the engine division open.

So Allison had already done a lot of something for nothing and had been burned badly by the government.
Allison had looked at two stage supercharging in 1938-39 but already had a number of projects in the works.

Now we get a bunch of people saying Allison should have funded two stage supercharger development themselves.
In 1939 Allison had 25 people working in the engineering dept. That includes the two men who ran the blueprint machine, the number of actual engineers was some want less.
Allison was trying to design the P-39 driveshaft and remote gearbox.
Allison was trying to finish off the pusher props, extension shafts on the Airacuda.
Allison was trying to come up with turbo version for the YP-38s.
Allison was working on the V-3420 24 cylinder engine.
Allison was trying to figure out how to mass produce the V-1710 engine, from 1931 through the end of 1939 Allison had built 78 engines.
The engineering staff was responsible for laying out the new production facilities, ordering the machine tools, designing the jigs and fixtures and designing any improvements, modifications.

Allison to government "Oh, you want a two stage supercharger in addition to all that? And you want us to pay for it until you can slip it into a future budget (but not this year?)
Ok, yeah, we will get right on that!!!!!" Don't hold your breath whispered in low tone.

 

[FLYBOYJ]

There are times where contract administrators will negotiate themselves into situations like this with no consideration to economics or to the rank and file designing and building this stuff. These contracts today are known as "as risk" contracts, "assuming" that the government will eventually open the checkbook. There's a lot of clauses in today's world when at risk contracts are paid, not only the "loaned money" is paid, but it is paid with interest.

 

[GregP]

Greg hits this nail on the head and many folks don't realize, forget or simply refuse to understand that manufacturers very rarely go into projects unfunded and/or unsolicited!!!!

I am reminded that Lady Houston gave generously to British aviation. In 1931, she donated £100,000 to Supermarine, allowing them to win the Schneider Trophy in that year.[3]​ The Royal Air Force's entry for the 1931 race for the trophy was hindered by political opposition. On 15 January 1931, the Air Ministry refused a last-minute request by the Royal Aero Club for funds for an entry. With the economic crisis the Cabinet vetoed RAF involvement and Government funding in a sporting event. Marshal of the Royal Air Force, Sir Hugh Trenchard held the view that there was no advantage as aircraft development would continue whether or not the UK competed.[8]​ The Ministry forbade the use of the aircraft that competed in the 1929 race; forbade RAF pilots of the High Speed Flight who were trained to fly these seaplanes, to take part; and said that it would not police the race course in 1931 in the busy shipping lanes in the Solent. The Royal Aero Club sent a statement to the Cabinet on 22 January 1931, offering to raise £100,000, if the Government would rescind the Air Ministry's decrees on planes, pilots and policing.

Many newspapers backing the opposition Conservative Party wanted to put pressure on Ramsay MacDonald's National government. One newspaper sent a telegram to MacDonald stating that, "To prevent the socialist government from being spoilsports, Lady Houston will be responsible for all extra expenses beyond what Sir Philip Sassoon[9]​ (President of the Royal Aero Club) says can be found, so that Great Britain can take part in the race for the Schneider trophy." The gift gave Lady Houston an opportunity to attack the Labour government, with the declaration "Every true Briton would rather sell his last shirt than admit that England could not afford to defend herself."

So, without Lady Houston's funding, we may never had had either the Merlin OR the Spitfire as we knew and KNOW them. While she was a boon to British aviation, Rolls-Royce, and Supermarine, Allison never had any such private OR public funding funding supplied by anyone.

If you use an inflation and currency calculator you can find that £100,000 in 1930 equates to $8,770,000 in 2020. Not exactly chicken feed, is it?

Now, I could be overstating it, but that's a pretty decent shot to a company in development of a privately-funded aviation engine!

Wow! It seems to me they did a very good job with Lady Houston's contribution in coming up with the R engine that turned into the Merlin engine. With that in mind, I'm not too ashamed of the Allison that got developed by a whole lot less funding and people who, if they were not exactly in a driving hurry, at least were not about to get bombed by the Luftwaffe. That certainly takes a bit of urgency out of the task.

I'm impressed with what Allison came up with in their considerably less well-funded development but, if pressed, would STILL take a Spitfire into battle in 1942 before I'd choose either a single-stage P-39 or P-40. Truth be told, I'd likely wait until the P-38J-25 that had hydraulic ailerons or the P-38L before choosing to fight in it.

 

[buffnut453]

So, without Lady Houston's funding, we may never had had either the Merlin OR the Spitfire as we knew and KNOW them. While she was a boon to British aviation, Rolls-Royce, and Supermarine, Allison never had any such private OR public funding funding supplied by anyone.

Greg, I love you brother...but there's so much that's wrong or misleading about this statement that it's really hard to know where to begin.

Yes, Lady Houston provided 100K to Supermarine (not Rolls Royce - that point is key) in 1931 for the Schneider Trophy race later that year. However, the impact of that funding on Spitfire or Merlin development was exactly ZERO. There was a lot of emotion at the time, and the outright winning of the Schneider Trophy was a tremendous boon to Britain at a time of considerable financial instability. However, in-year funding simply didn't allow enough time to develop anything truly new for the 1931 race. Lady Houston's investment did not change the direction of aircraft technology development in the UK.

Let's look at the airframe first. R.J. Mitchell took the Supermarine S6 that had won the 1929 race and tweaked the floats, lengthening them by 3ft, reducing their frontal area, and incorporating additional radiator cooling for the engine as part of the float design. The two original S6 racers from 1929 were updated with the different floats and designated S6A and 2 new airframes, which also integrated a more powerful Rolls Royce R engine, were designated S6B. None of that had any impact on design of the Spitfire. Apart from the floats, the rest of the airframe was pretty much unchanged from the 1929 Supermarine S6. As to evolution of the S6 into the Spitfire, the two airframes have nothing in common except the designer. The S6 still used wire bracing for the wings, tailplane and floats, whereas the Spitfire was of monocoque construction, which was an entirely different design philosophy.

As for the engine, the Rolls Royce R was developed from the Buzzard which was an up-scaled Kestrel, all of which were being worked on pretty much at the same time in the period 1927-1929. All these engines were funded by the British Government and they all used superchargers. The R powered the Supermarine S6 in the 1929 race and was further developed for the 1931 race, although it was still under UK Government funding (in April 1931, one of the R engines undertook an Air Ministry acceptance test which wouldn't be done if it was privately funded). None of these engines had any commonality with the Merlin which was privately funded (its original designation was PV12, PV standing for Private Venture) because Rolls Royce recognized that a larger engine would be needed to generate future power requirements.

Rolls Royce kicked off the PV12 in 1933 and started receiving Government funding in 1935 when it was decided that the PV12 should be the basis for requirements that ultimately led to the Spitfire and Hurricane. This was not some massive program initiated by the deep-pocketed Rolls Royce. Only 2 PV12 engines were built, passing bench testing in July 1934 with a first flight in February 1935. It was at this time that UK Government funding kicked in to evolve the PV12 into the the Merlin B. Again only 2 Merlin Bs were built, and they introduced glycol cooling (the PV12 employed evaporative cooling that had been much in vogue in the early 1930s but was operationally useless for combat aircraft). The Merlin C, E and F were developments of the B, with the latter being designated Merlin MkI as the first production example in 1936.

Ultimately, Trenchard was bang on the money. The RAF's participation in the 1931 Schneider Trophy race had no impact on aircraft technology development because all the main progress for the Schneider Trophy had already been made in 1929. In terms of engine development, the Kestrel and larger Buzzard were already well underway. Yes, the R engine provided some lessons on maintaining high performance but the fundamentals were already there thanks to the Kestrel, as was a team of experienced engine designers and developers to further evolve the technology.

All this whining about Allison not getting private or public funding reminds me of the tortuous conversations we've had about whether the Spitfire could have been turned into a decent long-range escort fighter. The pro lobby (typically Brits) contend that it was feasible. The anti lobby (typically Americans) often float the rhetorical question "If it was feasible, why wasn't it done?" closely followed with "couldda-wouldda-shouldda" for any attempt to argue the case. The simple reason the Spitfire wasn't developed into a long-range escort fighter was because the RAF had no need of that mission and so development of the airframe into that role didn't meet the funding threshold. We can say EXACTLY the same about development of the Allison engine.

The Allison was and is a great engine and, yes. it could have evolved into an effective competitor to the Merlin in the late 1930s if the US Government had invested in superchargers...but they didn't, and to do so would require different US Government funding decisions stretching back a decade prior. The US Government didn't see supercharger development as a priority and so didn't fund it. The British Government did invest, and the result was a solid base of experience within Rolls Royce that ultimately led to the PV12. Anything else is "couldda-wouldda-shouldda", I'm afraid.

 

[SaparotRob]

Just how difficult would it have been to build a short range Mustang?

 

[Shortround6]

Just how difficult would it have been to build a short range Mustang?

Easy, make the ground crew refuel the plane using 5 gallon jerry cans.

 

[GregP]

Greg, I love you brother...but there's so much that's wrong or misleading about this statement that it's really hard to know where to begin.

Yes, Lady Houston provided 100K to Supermarine (not Rolls Royce - that point is key) in 1931 for the Schneider Trophy race later that year. However, the impact of that funding on Spitfire or Merlin development was exactly ZERO. There was a lot of emotion at the time, and the outright winning of the Schneider Trophy was a tremendous boon to Britain at a time of considerable financial instability. However, in-year funding simply didn't allow enough time to develop anything truly new for the 1931 race. Lady Houston's investment did not change the direction of aircraft technology development in the UK.

Let's look at the airframe first. R.J. Mitchell took the Supermarine S6 that had won the 1929 race and tweaked the floats, lengthening them by 3ft, reducing their frontal area, and incorporating additional radiator cooling for the engine as part of the float design. The two original S6 racers from 1929 were updated with the different floats and designated S6A and 2 new airframes, which also integrated a more powerful Rolls Royce R engine, were designated S6B. None of that had any impact on design of the Spitfire. Apart from the floats, the rest of the airframe was pretty much unchanged from the 1929 Supermarine S6. As to evolution of the S6 into the Spitfire, the two airframes have nothing in common except the designer. The S6 still used wire bracing for the wings, tailplane and floats, whereas the Spitfire was of monocoque construction, which was an entirely different design philosophy.

As for the engine, the Rolls Royce R was developed from the Buzzard which was an up-scaled Kestrel, all of which were being worked on pretty much at the same time in the period 1927-1929. All these engines were funded by the British Government and they all used superchargers. The R powered the Supermarine S6 in the 1929 race and was further developed for the 1931 race, although it was still under UK Government funding (in April 1931, one of the R engines undertook an Air Ministry acceptance test which wouldn't be done if it was privately funded). None of these engines had any commonality with the Merlin which was privately funded (its original designation was PV12, PV standing for Private Venture) because Rolls Royce recognized that a larger engine would be needed to generate future power requirements.

Rolls Royce kicked off the PV12 in 1933 and started receiving Government funding in 1935 when it was decided that the PV12 should be the basis for requirements that ultimately led to the Spitfire and Hurricane. This was not some massive program initiated by the deep-pocketed Rolls Royce. Only 2 PV12 engines were built, passing bench testing in July 1934 with a first flight in February 1935. It was at this time that UK Government funding kicked in to evolve the PV12 into the the Merlin B. Again only 2 Merlin Bs were built, and they introduced glycol cooling (the PV12 employed evaporative cooling that had been much in vogue in the early 1930s but was operationally useless for combat aircraft). The Merlin C, E and F were developments of the B, with the latter being designated Merlin MkI as the first production example in 1936.

Ultimately, Trenchard was bang on the money. The RAF's participation in the 1931 Schneider Trophy race had no impact on aircraft technology development because all the main progress for the Schneider Trophy had already been made in 1929. In terms of engine development, the Kestrel and larger Buzzard were already well underway. Yes, the R engine provided some lessons on maintaining high performance but the fundamentals were already there thanks to the Kestrel, as was a team of experienced engine designers and developers to further evolve the technology.

All this whining about Allison not getting private or public funding reminds me of the tortuous conversations we've had about whether the Spitfire could have been turned into a decent long-range escort fighter. The pro lobby (typically Brits) contend that it was feasible. The anti lobby (typically Americans) often float the rhetorical question "If it was feasible, why wasn't it done?" closely followed with "couldda-wouldda-shouldda" for any attempt to argue the case. The simple reason the Spitfire wasn't developed into a long-range escort fighter was because the RAF had no need of that mission and so development of the airframe into that role didn't meet the funding threshold. We can say EXACTLY the same about development of the Allison engine.

The Allison was and is a great engine and, yes. it could have evolved into an effective competitor to the Merlin in the late 1930s if the US Government had invested in superchargers...but they didn't, and to do so would require different US Government funding decisions stretching back a decade prior. The US Government didn't see supercharger development as a priority and so didn't fund it. The British Government did invest, and the result was a solid base of experience within Rolls Royce that ultimately led to the PV12. Anything else is "couldda-wouldda-shouldda", I'm afraid.

The impact was zero? You have to be kidding.

The S.4, S.5, and S.6 led directly to the Spitfire AND the Merlin, which was a direct development of the S.6 engine.

At least, that's what my books on engines and the Spitfire say.

The S.4 and S.5 were decent, even good, but the lack of the S.6, had it never been raced, would have affected the Spitfire and the Merlin development. Throwing the equivalent of $8.7M at the effort didn't help immensely? Are you serious?

Well, I love you back, but will have to respectfully disagree with that.

Thing is, either way, the Spitfire and Merlin were winners together. They were great.

That doesn't detract from the fact that the Allison made a huge contribution to U.S. aviation in WWII, regardless of any nay-sayers claiming it didn't measure up. When it counted, the Allison was there and powered the mount of our two top aces. I'd say that qualifies as "good enough" at minimum.

 

[buffnut453]

The impact was zero? You have to be kidding.

The S.4, S.5, and S.6 led directly to the Spitfire AND the Merlin, which was a direct development of the S.6 engine.

At least, that's what my books on engines and the Spitfire say.

The S.4 and S.5 were decent, even good, but the lack of the S.6, had it never been raced, would have affected the Spitfire and the Merlin development. Throwing the equivalent of $8.7M at the effort didn't help immensely? Are you serious?

Well, I love you back, but will have to respectfully disagree with that.

Thing is, either way, the Spitfire and Merlin were winners together. They were great.

That doesn't detract from the fact that the Allison made a huge contribution to U.S. aviation in WWII, regardless of any nay-sayers claiming it didn't measure up. When it counted, the Allison was there and powered the mount of our two top aces. I'd say that qualifies as "good enough" at minimum.

But there would still have been a Supermarine S6 even if the Brits had pulled out of the 1931 Schneider event. The S6 won the 1929 event and was tweaked into the S6A and S6B for the 1931 race. So my argument stands...the 1931 Schneider Trophy race had zero impact on British aeronautical progress.

The Merlin was an amalgam of lessons learned with the Kestrel, Buzzard and the R (and there were over 4,000 Kestrels built). It's ludicrous to suggest that the Merlin was driven by the R when it patently wasn't. As I noted, some lessons were learned from the high-performance R engine but that wasn't the be-all and end-all. Lessons were also learned developing the larger Buzzard from the Kestrel, and from mass-producing the latter...and all were fitted with superchargers.

I can't disagree that the Allison made a huge contribution. However, it was at least 2-3 years behind the Merlin in performance...which means it couldn't have met the role the Merlin fulfilled in the period 1939-1942. After 1942, sure, the Allison is comparable but not before.

 

[drgondog]

Just how difficult would it have been to build a short range Mustang?

The P-509 would have range slightly greater than P-39/P-40 range in 1940-41 but projected faster and better climb than NA-73 as it was refined between RAF and NAA. P-09 proposed at 130 gal, then 150 for NA-73X , then 170 for Mustang I production, then 180 for Mustang IA and P-51, then 180 for P-51A

 

[Shortround6]

As for the engine, the Rolls Royce R was developed from the Buzzard which was an up-scaled Kestrel, all of which were being worked on pretty much at the same time in the period 1927-1929. All these engines were funded by the British Government and they all used superchargers. The R powered the Supermarine S6 in the 1929 race and was further developed for the 1931 race, although it was still under UK Government funding (in April 1931, one of the R engines undertook an Air Ministry acceptance test which wouldn't be done if it was privately funded). None of these engines had any commonality with the Merlin which was privately funded (its original designation was PV12, PV standing for Private Venture) because Rolls Royce recognized that a larger engine would be needed to generate future power requirements.

A few corrections.
The Kestrels did not start with superchargers, in service, although designed for them. They were soon added but both supercharged and non-supercharged Kestrels were offered for quite some time during the same period. The Kestrel was even offered with two different compression ratios in the unsupercharged form depending on fuel and intended use of the engine. Instructions for the "F" engine said that full throttle was not to be used below 2,000ft in the moderate compression engine, below 3,000ft in the high compression engine or below 11,500ft with the supercharged engine. Later supercharged Kestrels offered different compression ratios and different supercharger gears.

The Buzzard was always supercharged although both compression ratio and boost were limited. Sales were also limited. Most airframe makers couldn't quite figure out what to do with it.
The type "R" was a considerably beefed up/modified buzzard and this is where the benefit of the racing program came in. Partially because it got RR into rapid problem solving and modification. The type "R" was not a group of slightly modified engines but a succession of modifications, some of which were major. In the series was the first use by RR of the sodium cooled exhaust valve.

What lead to the Merlin was the need for an in-between engine between the Kestrel and the Buzzard/"R". RR needed a large engine than the Kestrel but the airframe makers weren't quite ready for the Buzzard/"R"/ Griffon (all three used the same bore x stroke=displacement). With better fuels and the knowledge from the "R" racing program RR could build as smaller engine than the Buzzard in size while making nearly as much power. Granted the Merlin went through several design changes before they steadied down.
RR placed Buzzard/Griffon on hold in 1933. This derated R engine was run in 1933 but not flown in aircraft. In 1938-39 they started back up again with the reconfigured/smaller on the outside Griffon II engine first run in Nov 1939. This was the engine the RN was looking at in it's 1940-41 aircraft.

The racing program was useful to RR but it wasn't as direct connection that some might think. The 1931 racers could use up to 17.5lbs of boost and the record setting flight may have used even more. It used a different fuel blend than the trophy race. RR may have learned a lot about supercharge design compared to other companies at this time.

Supercharger design was not stagnant but with low octane fuel in service engines a lot of potential problems did not show up.

 

[Shortround6]

Merlin, which was a direct development of the S.6 engine.

The R was a development of the Buzzard, kind of/sort of.
Rowledge added two additional cylinder hold down saddle studs per cylinder for example to help keep the engine together at higher power.
The moving parts owed a lot to the Buzzard the engine structure was designed for much higher loads.

Since the Merlin used a smaller bore and stroke and thus smaller valves (5.4 in bore vs 6 in bore). it is a bit hard to see the connection.
R engines may have used different connecting rods. Some, at least, used master and slave rods and not the fork and blade rods.

I am sure that Rowledge used a lot of knowledge used in the development of the R when working of the Merlin but to claim the Merin was a direct development of the engine/s used in the S.6 aircraft is stretching things, makes for a good story though

As outlined above, the Griffon was a closer descendent of the R than the Merlin was.

 

[SaparotRob]

The P-509 would have range slightly greater than P-39/P-40 range in 1940-41 but projected faster and better climb than NA-73 as it was refined between RAF and NAA. P-09 proposed at 130 gal, then 150 for NA-73X , then 170 for Mustang I production, then 180 for Mustang IA and P-51, then 180 for P-51A

Wrong! Have Bell build it.

 

[special ed]

So, my question is, how did Supermarine get their R engines for 1931? Did RR, out of the goodness of their heart give the enginese to Supermarine or did they buy them from RR with Lady Houston's donation? It would seem that there is more to the story. Surely the Air Ministry would try to preserve their pride by refusing RR to allow the engines to Supermarine. Possibly Lady Houston had influence in high places.

 

[GregP]

So, my question is, how did Supermarine get their R engines for 1931? Did RR, out of the goodness of their heart give the enginese to Supermarine or did they buy them from RR with Lady Houston's donation? It would seem that there is more to the story. Surely the Air Ministry would try to preserve their pride by refusing RR to allow the engines to Supermarine. Possibly Lady Houston had influence in high places.

I'm sure there was more to the story.

I'm also fairly sure that the whole story may never be known.

But, if you take a talented group of aircraft and engine designers and add $8.7M to their war chest, I'm pretty sure you get much better results from their efforts than would have been achieved without the addition of said extra funds. If nothing else, they at LEAST get to try a few things they would not have been able to try without the extra money.

 

[buffnut453]

So, my question is, how did Supermarine get their R engines for 1931? Did RR, out of the goodness of their heart give the enginese to Supermarine or did they buy them from RR with Lady Houston's donation? It would seem that there is more to the story. Surely the Air Ministry would try to preserve their pride by refusing RR to allow the engines to Supermarine. Possibly Lady Houston had influence in high places.

The RAF performed a volte face in January 1931 and agreed to support the Schneider Trophy entry, and the High Speed Flight was re-formed at Calshot...but this was only 9 months before the race. The £100K from Lady Houston was only to cover the additional costs of the Schneider Trophy race, over and above what was already contracted with Rolls Royce and Supermarine. Thus, her contribution probably landed in R.J. Mitchell's lap around the same time as the RAF agreed to support the effort.

I'm pretty sure Supermarine did no preparation for the 1931 race after the RAF withdrew funding in late 1929/early 1930. In many respects, it was the lack of time between the funding tap being turned on and the actual race that limited the refinements to the S6, leading to the S6B. There are some tasks that simply can't be accelerated, and major redesign of an airframe is one of those things....try to speed it up too much and you'll either end up with a crap design or a smoking heap and a dead pilot (or both).

As for the Rolls Royce R development, that seems to have entirely stalled in 1930. Looking at this table that records the individual histories of each of the R engines, the only actions undertaken in 1930 were devoted to non-aviation applications of the engine (e.g. direct-drive shafts to power water speed record attempts):

Rolls-Royce R - Wikipedia

en.wikipedia.org

There isn't a single event in 1930 related to aviation applications of the R engine. That strongly suggests that Rolls Royce also ceased development of the R during that period, with things only picking up after the RAF involvement was re-energized in January 1931.