Where to Get a Rolls Royce Merlin
Gnome de PPRuNe
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 60
Posts: 12,597
Received 275 Likes
on
153 Posts
I think I read somewhere that Dwight Thorne and others who prepare race ready Merlins for Reno replace various Merlin parts (con rods?) with Aliison parts as they are less prone to breaking.
Join Date: Mar 2008
Location: England
Age: 65
Posts: 303
Likes: 0
Received 0 Likes
on
0 Posts
There was the A-36 variant of the Mustang which was reinforced and had a redesigned wing to carry ordnance and incorporated dive brakes.
This used the Allison engine only.
This used the Allison engine only.
Join Date: Apr 2007
Location: moraira,spain-Norfolk, UK
Age: 82
Posts: 389
Likes: 0
Received 0 Likes
on
0 Posts
My late father told me of burying Merlins and other stuff at XXXXXX, which was to
be handed over to the Navy. I could figure where from his service records, but I
am away from home just. He did say he thought they were excavated again within a
day or two by the locals.
be handed over to the Navy. I could figure where from his service records, but I
am away from home just. He did say he thought they were excavated again within a
day or two by the locals.
There is a section in Stanley Hooker's book "Not Much of an Engineer", where they were developing the first Merlin with two-stage supercharging (Merlin 60?). Someone suggested that it might be worthwhile installing one in a Mustang. The rest, as they say, is history.
Last edited by India Four Two; 7th Aug 2016 at 06:07.
I2-4's post reinforces the fact that the Allison P51 was a sound aircraft at low level but the supercharging was insufficient for high level work. No one wants or needs a heavy, troublesome two-stage supercharger to take them to Fl400 in the modern day, no Mustang operates anywhere close to full-throttle height of an Allison, let alone a Merlin 61 so what's the problem - authenticity aside?
Terry,
Thank you! I don't have access to my copy, so I couldn't check. However, I was pretty sure that it wasn't suggested by Sir Stanley himself.
http://www.mustang.gaetanmarie.com/articles/harker.htm
Thank you! I don't have access to my copy, so I couldn't check. However, I was pretty sure that it wasn't suggested by Sir Stanley himself.
http://www.mustang.gaetanmarie.com/articles/harker.htm
The story of the Merlin Mustang began with a phone call from Wing Commander Ian Campbell-Orde, CO of ARDU at Duxford, to Ronnie Harker, Rolls-Royce service liaison pilot, inviting him to fly a newly arrived Allison Mustang.
On 30th April 1942 he flew AG422 for thirty minutes. He made a subsequent report to Sir A. F. Sidgreaves, Managing Director, and E. W. Hives, Director and General Works Manager, saying in part,
Ray Dorey, R-R Manager at Hucknell, suggested Harker go direct to Hives. Following conversation with Hives, Hives immediately phoned Sir Wilfred Freeman, Vice Chief of the Air Staff with the recommendation that an aircraft be provided for conversion.
And the rest is history.
The American conversion to the Merlin came at the behest of the American Ambassador to Britain, John G. Winant, instructing General H. H. Arnold, Commander of the USAAF, to give it 'Priority 1' in the factory. (letter penned by W. Lappin, Hives Personnal Assistant, to Hives). From the very start of the program the Americans were involved.
As an aside, there was at one time a very serious examination made by British authorities of producing the Mustang in Britain.
On 30th April 1942 he flew AG422 for thirty minutes. He made a subsequent report to Sir A. F. Sidgreaves, Managing Director, and E. W. Hives, Director and General Works Manager, saying in part,
This aircraft should prove itself a formidable low and mid altitude fighter.
The point which strikes me is that with a powerful and good engine like the Merlin 61, its performance should be outstanding, as it is 35 m.p.h. faster than a Spitfire V at roughly the same power.
The point which strikes me is that with a powerful and good engine like the Merlin 61, its performance should be outstanding, as it is 35 m.p.h. faster than a Spitfire V at roughly the same power.
And the rest is history.
The American conversion to the Merlin came at the behest of the American Ambassador to Britain, John G. Winant, instructing General H. H. Arnold, Commander of the USAAF, to give it 'Priority 1' in the factory. (letter penned by W. Lappin, Hives Personnal Assistant, to Hives). From the very start of the program the Americans were involved.
As an aside, there was at one time a very serious examination made by British authorities of producing the Mustang in Britain.
Last edited by megan; 8th Aug 2016 at 04:19.
The story of the Merlin Mustang began with a phone call from Wing Commander Ian Campbell-Orde, CO of ARDU at Duxford, to Ronnie Harker, Rolls-Royce service liaison pilot, inviting him to fly a newly arrived Allison Mustang.
So the Mustang was 35mph faster than the Spitfire at the same power input? Is this because of a better wing? And doesn't that mean that the Spitfire was/should have been obsolete after the Merlin Mustang was available?
Does the fact that Campbell-Orde invited a Rolls Royce pilot to fly the Mustang indicate that he was already thinking along the same lines?
So the Mustang was 35mph faster than the Spitfire at the same power input? Is this because of a better wing? And doesn't that mean that the Spitfire was/should have been obsolete after the Merlin Mustang was available?
Major Thomas Hitchcock Jr was the Assistant Air Attaché at the London American Embassy, and a great promoter of the P-51 from the earliest of days. A memorandum he wrote,
8 October 1942
SUBJECT: History of the Mustang P-5l Aircraft.
The Mustang P-5l was ordered by the English directly from the North American Company. The order did not pass through Wright Field, and the airplane probably does not conform fully with the Wright Field handbook.
In the Air Fighter Development Unit Report No.43, dated May 5, 1942, the Mustang is described as ““an excellent low and medium altitude lighter and certainly the best American fighter that has so far reached this country". Comparisons were made with the Spitfire VB in which it was faster than the VB at all altitudes up to 25,000 feet. At 25,000 feet it went about the same speed as the Spitfire VB, although at this altitude the Allison engine was developing 290 less horsepower than the Merlin engine in the Spitfire. Estimates have been made that with the same horsepower Mustang is twenty to twenty five miles per hour faster than the Spitfire VB.
The reasons for the remarkably low drag of the Mustang are not fully understood on this side of the ocean. The English think it is only partly due to the laminar flow wing.
The Rolls people became very much interested in the possibilities of Mustang airframe with the Merlin engine. Estimates were made as to the speeds that could be obtained with the installation of the 6l and 20 Merlin. The Air Ministry instructed the Rolls people to install live Merlin 61 engines in Mustang airplanes. Simultaneously with this development it was arranged to have the North American Company install a Packard version of the Merlin 61 in the Mustang airframe. Requests were sent to the United States to have the Packard Company start manufacturing Merlin 61s as promptly as possible.
The interesting qualities of the Mustang airframe were brought to the attention of General Arnold and Admiral Towers when they were in London in June last, by the American Ambassador; Air Chief Marshal Sir Charles Portal, Chief of Air Stall`; Air Chief Marshal Sir Sholto Douglas, Commander in Chief Fighter Command, and Air Marshal F.J.Linnell, Ministry of Aircraft Production - Research and Development. Robert Lovell, Assistant Secretary of War for Air, was also advised by letter dated .June 5, 1942, of the importance which English and various American representatives attach to the Mustang airframe and the desirability of energetically pushing the Merlin development.
ln Air Fighter Development Unit Report No.55 dated August 9, 1942, on the Tactical Trials of the Focke Wulf 190, in which comparisons were made of the fighting qualities of various English and American tighter planes with the FW l90. in all respects except rate of climb the Mustang appeared to do the best against the 190.
Dr. Edward Warner, when he was in this country in August and September, 1942, made considerable inquiry at Farborough as to the reason for the low drag of the Mustang airframe. The Farnborough technicians were only willing to ascribe a small amount of the added speed to the laminar flow wing. Dr. Warner`s reports on this subject are of interest.
Mr. Legarra. North American representative. reported when he came back from the United States in the early part of September, that the Mustang had the lowest priority that could be granted to an airplane. Air Chief Marshal Sir Wilfred Freeman, Vice-Chief of the Air Stall. on a suggestion made by Mr. Legarra of the North American Company that the Mustang could be assembled in England from parts fabricated in the United States. has wired to the United States to have a study made as to the feasibility of this plan.
The Mustang is one of the best, if not the best, fighter airframe that has been developed in the war up to date. lt has no compressibility or flutter troubles, it is manoeuvrable at high speeds, has the most rapid rate of roll of any plane except the Focke Wulf 190, is easy to fly and has no nasty tricks. lts development and use in this theatre has suffered for various reasons. Sired by the English out of an American mother, the Mustang has had no parent in the Army Air Corps or at Wright Field to appreciate and push its good points. lt arrived in England at a time when great emphasis was placed on high altitude performance, and because it was equipped with a low altitude engine, was of no particular interest to English Fighter Command. The Mustang was turned over to the English Army Co-operation Command, for low altitude work. lt performed well at Dieppe. The pilots who fly the Mustang are most enthusiastic about its performance.
The development of the Mustang as a high altitude fighter will be brought about by cross-breeding it with the Merlin 61 engine. While the prospect of an English engine in an American airframe may appeal to the sentimental qualities of those individuals who are interested in furthering Anglo-American relationships by joining hands across the water, it does not fully satisfy important people on both sides of the Atlantic who seem more interested in pointing with pride to the development of a 100% national product than they are concerned with the very difficult problem of rapidly developing a fighter plane that will be superior to anything the Germans have.
SUBJECT: History of the Mustang P-5l Aircraft.
The Mustang P-5l was ordered by the English directly from the North American Company. The order did not pass through Wright Field, and the airplane probably does not conform fully with the Wright Field handbook.
In the Air Fighter Development Unit Report No.43, dated May 5, 1942, the Mustang is described as ““an excellent low and medium altitude lighter and certainly the best American fighter that has so far reached this country". Comparisons were made with the Spitfire VB in which it was faster than the VB at all altitudes up to 25,000 feet. At 25,000 feet it went about the same speed as the Spitfire VB, although at this altitude the Allison engine was developing 290 less horsepower than the Merlin engine in the Spitfire. Estimates have been made that with the same horsepower Mustang is twenty to twenty five miles per hour faster than the Spitfire VB.
The reasons for the remarkably low drag of the Mustang are not fully understood on this side of the ocean. The English think it is only partly due to the laminar flow wing.
The Rolls people became very much interested in the possibilities of Mustang airframe with the Merlin engine. Estimates were made as to the speeds that could be obtained with the installation of the 6l and 20 Merlin. The Air Ministry instructed the Rolls people to install live Merlin 61 engines in Mustang airplanes. Simultaneously with this development it was arranged to have the North American Company install a Packard version of the Merlin 61 in the Mustang airframe. Requests were sent to the United States to have the Packard Company start manufacturing Merlin 61s as promptly as possible.
The interesting qualities of the Mustang airframe were brought to the attention of General Arnold and Admiral Towers when they were in London in June last, by the American Ambassador; Air Chief Marshal Sir Charles Portal, Chief of Air Stall`; Air Chief Marshal Sir Sholto Douglas, Commander in Chief Fighter Command, and Air Marshal F.J.Linnell, Ministry of Aircraft Production - Research and Development. Robert Lovell, Assistant Secretary of War for Air, was also advised by letter dated .June 5, 1942, of the importance which English and various American representatives attach to the Mustang airframe and the desirability of energetically pushing the Merlin development.
ln Air Fighter Development Unit Report No.55 dated August 9, 1942, on the Tactical Trials of the Focke Wulf 190, in which comparisons were made of the fighting qualities of various English and American tighter planes with the FW l90. in all respects except rate of climb the Mustang appeared to do the best against the 190.
Dr. Edward Warner, when he was in this country in August and September, 1942, made considerable inquiry at Farborough as to the reason for the low drag of the Mustang airframe. The Farnborough technicians were only willing to ascribe a small amount of the added speed to the laminar flow wing. Dr. Warner`s reports on this subject are of interest.
Mr. Legarra. North American representative. reported when he came back from the United States in the early part of September, that the Mustang had the lowest priority that could be granted to an airplane. Air Chief Marshal Sir Wilfred Freeman, Vice-Chief of the Air Stall. on a suggestion made by Mr. Legarra of the North American Company that the Mustang could be assembled in England from parts fabricated in the United States. has wired to the United States to have a study made as to the feasibility of this plan.
The Mustang is one of the best, if not the best, fighter airframe that has been developed in the war up to date. lt has no compressibility or flutter troubles, it is manoeuvrable at high speeds, has the most rapid rate of roll of any plane except the Focke Wulf 190, is easy to fly and has no nasty tricks. lts development and use in this theatre has suffered for various reasons. Sired by the English out of an American mother, the Mustang has had no parent in the Army Air Corps or at Wright Field to appreciate and push its good points. lt arrived in England at a time when great emphasis was placed on high altitude performance, and because it was equipped with a low altitude engine, was of no particular interest to English Fighter Command. The Mustang was turned over to the English Army Co-operation Command, for low altitude work. lt performed well at Dieppe. The pilots who fly the Mustang are most enthusiastic about its performance.
The development of the Mustang as a high altitude fighter will be brought about by cross-breeding it with the Merlin 61 engine. While the prospect of an English engine in an American airframe may appeal to the sentimental qualities of those individuals who are interested in furthering Anglo-American relationships by joining hands across the water, it does not fully satisfy important people on both sides of the Atlantic who seem more interested in pointing with pride to the development of a 100% national product than they are concerned with the very difficult problem of rapidly developing a fighter plane that will be superior to anything the Germans have.
This fighter business in Europe is a little bit like the women`s dress business. the question of styles and fashions keeps changing all the time. When 1 went to London about seven months ago, the English Fighter Command wouldn`t look at anything that wouldn`t fly at 28.000 to 30,000 feet and have plenty of speed. Since then the Focke Wulf has come into active participation on the Western Front; and now all the talk you hear is about greater climb and additional acceleration. This is because the Focke Wulf has those capabilities to a very great degree.
The whole story of the English Fighter planes is more a story of engines than it is of the planes themselves. When you talk about engines, you get practically down to the Rolls engine — that is the Rolls Merlin engine. lt started out at about 850 h.p. with a critical altitude of around 15.000 feet. This had a cubic displacement of 1650 cubic inches. ln 1939 and 1940 they increased the h.p. rating by some 300 or 4()0 h.p.. up to 1200 h.p.. but didn`t increase the altitude much. ln 1942 they came along with Merlin 46 and 47 and boosted the altitude more than they did the h.p.
Now, when I first went over there, I was rather surprised to run into a report that the Mustang. which is our P-51, was 35 miles an hour faster than the Spitfire V at around 15,000 feet. At 25,000 feet it went a few miles an hour faster and was pulling 290 less h.p. That indicated there must be something aerodynamically good about the Mustang. Dr. E.P. Warner, prominent aeronautical engineer in this country. came over to England and made considerable studies as to the aerodynamic quality of fighter planes. He reduced it to co-efficient drag. The Mustang has a very low co-efficient drag as compared to the Spitfire and that is why it goes faster. It has the lowest co-efficient of drag of any plane in that theatre; and the English gave it a very good report and became very enthusiastic about it.
They said. "Now, if we can put a high altitude engine in this plane we will have the answer to a maiden`s prayer" So they put a Merlin 61 engine in it; and they have got us to put one into it in this country. Originally they were going to put in the 61 that peaked at 30.000 feet. Then because the Focke Wulf peaks at 21,000 feet (and because the Spitfire is lighter than the Mustang) they decided the thing to do was to let the Spitfires have the high cover, and try and make the Mustang a fighter against the Focke Wulf. They took the Merlin 61 engine and put a different blower ratio on it so as to get the critical altitude at 21,000 feet, and this is the plane which gives about 426 miles an hour at 21,000 feet. Their original thought was to bring it up higher with the 61 version that peaked at 30.000 feet.
The white hope of the English, in order to combat the FW 190, and particularly the Focke Wulf with the fully rated engine (which they are probably up against now) is by putting the Merlin 61 into the Mustang. They believe that will be the best fighting plane for the next year or two; and their preliminary tests indicate they are right. There is one bad thing about the Spitfires - they don`t have a carburettor that allows them to sustain negative Those planes won`t dive particularly fast, and at 450 miles an hour they are not very manoeuvrable laterally in a dive. Fortunately. the Mustang is manoeuvrable at high speed. There is no flutter trouble and it has a rapid rate of roll. That rate of roll we didn`t hear about until the Focke Wulf came out.
They found the Focke Wulf would start to the right and all of a sudden it would flick over and go the other way. Now, in the tests made with the Focke Wulf that they have captured, the plane that would come nearest to staying with it on this reverse twist was the Mustang. That steamed them all up; and they are now negotiating to try and build the Mustang in the United Kingdom and equip it with the Merlin engine; and they are doing all they can to try and get us to build more Mustangs for that particular theatre.
The whole story of the English Fighter planes is more a story of engines than it is of the planes themselves. When you talk about engines, you get practically down to the Rolls engine — that is the Rolls Merlin engine. lt started out at about 850 h.p. with a critical altitude of around 15.000 feet. This had a cubic displacement of 1650 cubic inches. ln 1939 and 1940 they increased the h.p. rating by some 300 or 4()0 h.p.. up to 1200 h.p.. but didn`t increase the altitude much. ln 1942 they came along with Merlin 46 and 47 and boosted the altitude more than they did the h.p.
Now, when I first went over there, I was rather surprised to run into a report that the Mustang. which is our P-51, was 35 miles an hour faster than the Spitfire V at around 15,000 feet. At 25,000 feet it went a few miles an hour faster and was pulling 290 less h.p. That indicated there must be something aerodynamically good about the Mustang. Dr. E.P. Warner, prominent aeronautical engineer in this country. came over to England and made considerable studies as to the aerodynamic quality of fighter planes. He reduced it to co-efficient drag. The Mustang has a very low co-efficient drag as compared to the Spitfire and that is why it goes faster. It has the lowest co-efficient of drag of any plane in that theatre; and the English gave it a very good report and became very enthusiastic about it.
They said. "Now, if we can put a high altitude engine in this plane we will have the answer to a maiden`s prayer" So they put a Merlin 61 engine in it; and they have got us to put one into it in this country. Originally they were going to put in the 61 that peaked at 30.000 feet. Then because the Focke Wulf peaks at 21,000 feet (and because the Spitfire is lighter than the Mustang) they decided the thing to do was to let the Spitfires have the high cover, and try and make the Mustang a fighter against the Focke Wulf. They took the Merlin 61 engine and put a different blower ratio on it so as to get the critical altitude at 21,000 feet, and this is the plane which gives about 426 miles an hour at 21,000 feet. Their original thought was to bring it up higher with the 61 version that peaked at 30.000 feet.
The white hope of the English, in order to combat the FW 190, and particularly the Focke Wulf with the fully rated engine (which they are probably up against now) is by putting the Merlin 61 into the Mustang. They believe that will be the best fighting plane for the next year or two; and their preliminary tests indicate they are right. There is one bad thing about the Spitfires - they don`t have a carburettor that allows them to sustain negative Those planes won`t dive particularly fast, and at 450 miles an hour they are not very manoeuvrable laterally in a dive. Fortunately. the Mustang is manoeuvrable at high speed. There is no flutter trouble and it has a rapid rate of roll. That rate of roll we didn`t hear about until the Focke Wulf came out.
They found the Focke Wulf would start to the right and all of a sudden it would flick over and go the other way. Now, in the tests made with the Focke Wulf that they have captured, the plane that would come nearest to staying with it on this reverse twist was the Mustang. That steamed them all up; and they are now negotiating to try and build the Mustang in the United Kingdom and equip it with the Merlin engine; and they are doing all they can to try and get us to build more Mustangs for that particular theatre.
It was indeed fortuitous that Tommy Hitchcock was who he was and where he was at this pivotal period in the war, having not only the insight to recognise the Mustang’s potential but also the aforementioned influence. There is no doubt that some of this enthusiasm at least was a result of his liaison with Rolls·Royce, a company with whose officials he had a personal and fruitful rapport. His death in April 1944 was one of life`s tragic ironies in that it happened when he was flying the very aircraft that he had done so much to promote.
The ‘great white hope’ he mentions is because the British at one point did see the Mustang as becoming its prime fighter, given its performance. There was much doubt in the wind at the time as to whether further development of the Spitfire would be ready and able in time to meet the FW 190 threat, and the same with the Tyhoon then under development. In mid June 1942 Air Chief Marshall Sir W. R. Freeman was even pressing for a Griffon powered P-51, to make a super low altitude fighter.
Just my own opinion. F. W. Meredith was a British engineer working at the Royal Aircraft Establishment, Farnborough, and wrote a paper in 1936 detailing what later became known as the Meredith effect. The Spitfire was the first to my knowledge to employ this effect in the design of its radiators. Compared to the Mustang it was not as well integrated on the Spitfire IMHO. The ram air into the duct on the Mustang did not swallow the aircrafts boundry layer as on the Spitfire. Looking at a Spitfire parked next to a Mustang at an air show I thought the skinning on the Spitfire was full of undulations as compared to the Mustangs very clean/smooth surface. This surface finish on the Mustang was commented upon much by the British when it first arrived. Why the Mustangs low CD? Your guess is as good as mine.
Very efficient laminar flow wing?
Though the Mustang's war record confirmed expectations of appreciable improvements in speed and range as a result of the low-drag design, practical experience with this and other aircraft using advanced NACA sections in the 1940s also showed that the airfoil did not perform quite as spectacularly in flight as in the laboratory. Manufacturing tolerances were off far enough, and maintenance of wing surfaces in the field careless enough, that some significant points of aerodynamic similarity between the operational airfoil and the accurate, highly polished, and smooth model that had been tested in the controlled environment of the wind tunnel were lost.* Still, despite manufacturing irregularities and the detrimental effects of actual use, the Mustang's modified 4-series section, with its pressure distributions and other features, proved an excellent high speed airfoil. The delineation of it and other laminar-flow airfoils was thus a great contribution by Langley, even if not exactly to the degree advertised by NACA publicists like George Gray, who claimed in Frontiers of Flight that "the shape of this new wing permitted the flow to remain laminar until the air had traveled about half way along the chord." According to Langley engineers who knew what it took in practice to achieve success, Gray's claim was an exaggeration. Because the percentage drag effect of even minor wing surface roughness or dirt increased as airfoils became more efficient, laminar flow could be maintained in actual flight operation only in a very small region near the leading edge of the wing.
* After the Two-Dimensional Low-Turbulence Pressure Tunnel was put into operation in the spring of 1941, Langley researchers undertook a systematic study of the 63-, 64-, 65-, and 66-series sections. Working 48 hours a week each in three daily shifts, the men of Jacobs's section ran these tests at Reynolds numbers of 3, 6, and 9 million, with smooth surfaces and with a standard carborundum roughness on the leading edge. Though results made it clear that ideal laminar-flow airfoils were practically impossible to achieve, Jacobs would not let this information be published. Only after Jacobs resigned from Langley in 1944 did the NACA finally publish a report stating this conclusion: Laurence K. Loftin, Jr., "Effects of Specific Types of Surface Roughness on Boundary-Layer Transition," Adv. Conf. Rpt. L5J29a, 1946.
* After the Two-Dimensional Low-Turbulence Pressure Tunnel was put into operation in the spring of 1941, Langley researchers undertook a systematic study of the 63-, 64-, 65-, and 66-series sections. Working 48 hours a week each in three daily shifts, the men of Jacobs's section ran these tests at Reynolds numbers of 3, 6, and 9 million, with smooth surfaces and with a standard carborundum roughness on the leading edge. Though results made it clear that ideal laminar-flow airfoils were practically impossible to achieve, Jacobs would not let this information be published. Only after Jacobs resigned from Langley in 1944 did the NACA finally publish a report stating this conclusion: Laurence K. Loftin, Jr., "Effects of Specific Types of Surface Roughness on Boundary-Layer Transition," Adv. Conf. Rpt. L5J29a, 1946.
Join Date: Jun 2014
Location: eastcoastoz
Age: 76
Posts: 1,699
Likes: 0
Received 0 Likes
on
0 Posts
megan,
Thanks so much for your valuable contribution to the discussion.
Of course, the Merlin Mustang was very much an aircraft that was 'right for its time'.
Some years back, I had the opportunity to buy a Merlin (as a toy) at what appeared to be a good price.
Of course, I found out the thing had suffered a catastrophic crankshaft failure.
Bummer.
With a little bit if thread-drift, I occasionally wonder why the Germans didn't develop the Fw190/BMW-801 combination
to the point where it could counter its very effective adversary, the Mustang.
The Ta-152 aside, too little too late?
.
Thanks so much for your valuable contribution to the discussion.
Of course, the Merlin Mustang was very much an aircraft that was 'right for its time'.
Some years back, I had the opportunity to buy a Merlin (as a toy) at what appeared to be a good price.
Of course, I found out the thing had suffered a catastrophic crankshaft failure.
Bummer.
With a little bit if thread-drift, I occasionally wonder why the Germans didn't develop the Fw190/BMW-801 combination
to the point where it could counter its very effective adversary, the Mustang.
The Ta-152 aside, too little too late?
.
Last edited by Stanwell; 9th Aug 2016 at 15:12.
Gnome de PPRuNe
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 60
Posts: 12,597
Received 275 Likes
on
153 Posts
I believe that's the Meredith effect referred to by Megan, last para post 32.
Wasn't the Mustang alleged to obtain some thrust from the radiator exit due to thermal expansion effects?
In the case of the Mustang, the air duct pumping system at full speed at 25,000 feet was processing some 500 cubic feet of air per second, and discharge speed of the outlet was between 500 and 600 feet per second relative to the airplane. This air jet counteracted much of the radiator drag and had the effect of offsetting most of the total cooling drag. To offer some approximate numbers, the full power propeller thrust was about 1,000 pounds and the radiator drag (gross) was about 400 pounds, but the momentum recovery was some 350 pounds of compensating thrust--for a net cooling drag of only some 3% of the thrust of the propeller.
A search on the web has failed to find the documents, but should anyone be interested they can PM for a full copy of the rather lengthy speech, and also a copy of Merediths original paper.
Join Date: Sep 2007
Location: On the Rump of Pendle Hill Lancashi
Posts: 614
Likes: 0
Received 0 Likes
on
0 Posts
I had a strange hobby of collecting Aero engines and "Bits" that still worked, I had Merlin's,Griffon's Alvis Leonides, Issotta Frashini W18s, many different types of Props and engine ancillary items, the problem was my hobby started in the 1980s became a sort of small and sought after business, which I had not intended, indeed many of my working engines finished up in the US of A, however by the end of the 1999/2001 it was more and more difficult to find "Good Uns" so my accidental secondary business slowly subsided until as now I only have very simple items left from that "Romantic Hobby"....even with all my contacts I have not heard of any serviceable Merlin's available at less than Lottery winners prices....but it had to be due to rareness of said beast.
Megan, it would be interesting to see how a P-51 with a minimum drag in the shape of a streamlined nose w/o any cooling configuration, as a benchmark, would compare to the P-51 with the existing configuration and a P-51 with a fictitious radial engine with aircooled cilinders. I wouldn't be surprised if the Merlin version even with the large cooler-cum-thrust would be better than the radial engine configuration. The question renmains why the P-51 was so much more favourable drag-wise , than the Spitfire.