Thanks. Yes, it is obvious from the modifications required that the 4,000 lb HC bomb wouldn't fit in any of the cells.
Cheers
Steve
Advantages & Disadvantages: Nations & Doctrine, Aircraft and Technology of WWII
- Thread starter Zipper730
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Cheers
Steve
Here is a bomb loading diagram for the Wellington from one of the old 4+ publications, purloined from another site. Unfortunately there is no detailed information on the modified bomb bay.
Perhaps more pertinent is this video:
View: https://www.youtube.com/watch?v=UcrbIwXI1jE
There appears to be a complete 'box' built within the bomb bay, from which all the longitudinal beams and doors (with the exception of the outer doors) have been removed. The unused front and rear areas of the bay have been blanked off, is this the fabric covers? The outer doors seem to close onto this box, leaving the bottom of the bomb exposed.
Cheers
Steve
Perhaps more pertinent is this video:
View: https://www.youtube.com/watch?v=UcrbIwXI1jE
There appears to be a complete 'box' built within the bomb bay, from which all the longitudinal beams and doors (with the exception of the outer doors) have been removed. The unused front and rear areas of the bay have been blanked off, is this the fabric covers? The outer doors seem to close onto this box, leaving the bottom of the bomb exposed.
Cheers
Steve
Last edited:
- Thread starter
- #103
wuzak
Captain
And which jet engine would that be?
The early GE engines were based very heavily on Whittle's designs.
As for GE compressor technology, the aero engine firms of Wright, Pratt and Whitney and Allison used GE compressors for a while, but moved to making their own, leading to improved performance.
MiTasol
1st Lieutenant
As you are no doubt aware there are significant differences between the compressor on a turbocharger and the compressor of a piston engine supercharger.
The supercharger integral with any engine is optimized for a specific altitude (usually under 20,000 ft) and the specific engine it is incorporated in. It runs on the same oil as the rest of the engine and using the same oil pressure (usually under 100psi in cruise) as the rest of the engine. Likewise the temperatures of all components in an integrated supercharger are not massively different from the temperatures of the adjacent components. Additionally it is downstream of the carburetor so the air it is compressing is mixed with fuel droplets which change the relative density and airflow characteristics of the air it is processing. As a result the compressor integral with the engine requires compromises far different from those in the turbo-superchargers compressor.
Turbo-supercharger compressors on the other hand have their own oil systems operating at over 150psi as that is the pressure required by the wastegate regulator. The temperatures of the adjacent parts are far hotter and colder than the compressor itself, it processes fuel free air and is optimized in most cases for 25,000ft or above but not for any specific engine as the same turbo-supercharger must operate efficiently on any engine of the power range it is designed for - for example the same turbo can be used on R-1820, R-1830 and V-1710, all of which have different swept volumes and different operating rpms.
Centrifugal turbojet compressors operate in a very similar manner and under similar conditions to the turbo-supercharger - the main difference being the combustion chambers of the jet replace the piston engine as the source of high temperature air. In both cases the compressor provides the air for combustion and the turbine extracts the temperature to provide the power that drives the compressor. In the turbojet the aim is to have some residual temperature to provide thrust.
Likewise the turbines of the early turbojets were very similar to the turbines in the turbocharger and operated under the same conditions - both being driven by large volumes of high temperature gasses.
Sanford Moss had already spent 40 years working on gas turbine engines (he ran his first, 100% his own design, at Cornell University in 1902, not 1914 as I wrote from memory earlier) before he saw his first Whittle engine drawings and was far ahead of Whittle and co on understanding the aerodynamics, thermodynamics and metallurgy required for the early turbine engines. Don't forget his turbo-supercharger test rig was in reality a gas turbine engine and that he was using a single combustion chamber to provide the temperatures and gas flows for his turbines, rather than the multiple small cans used on turbojet, and was extracting the maximum possible heat from the gas flow in order to maximize the power driving the compressor..
Yes the early GE engines were very closely based on Whittles BUT the compressors and turbines were considerably enhanced by Moss's vastly greater knowledge of turbines operating in high temperature exhaust fumes and of compressors operating at all altitudes. It is also possible that he may have incorporated some of his combustion chamber technology or metallurgy though that is probably far less likely as he was only aiming at producing the required turbine inlet temperatures and mass air flow for testing the turbine whereas an operating engine must also ensure continuous combustion at all altitudes and power settings.
Last edited:
MiTasol
1st Lieutenant
wuzak
Captain
No, they work the same.
They produce a given mass air flow and outlet pressure based on their speed, and inlet conditions. The design of the compressor is based around those requirements.
Yes, most compressors in supercharged aero engines are optimized for a certain altitude, when they were not coupled to a turbo.
The altitude being less than 20,000ft is due to the limitations of single stage design and the compromise between low and high altitude operation. Have a higher critical altitude and the lower altitudes suffer.
Still, that critical altitude could be changed by a simple gearing change.
The compressors in turbos didn't have to run the same pressure ratios at high altitudes as compressors mounted on the engine.
The pressure ratio required at 25,000ft for a turbocharger was ~2.7:1. At a boost pressure of +9psi (~48inHg MAP) it was 4.3:1. At +18psi boost (~67inHg MAP) it was 6:1.
It wasn't superior design that enabled turbo compressors to have higher critical altitudes - it was an easier target (the target being an outlet pressure at the carburetor inlet of standard sea level pressure).
The lubrication systems, etc, have little to do with the actual functioning of the compressor impeller and volute.
As for working with different engines, I dare say that the critical altitudes varies - the R-1820 and R-1830 would be similar, as their air requirements and boost levels were similar, while the V-1710 would require more mass flow, so the turbo would likely have a lower critical altitude (maximum rpm reached at lower altitude) than the others. The V-1710 was smaller in capacity than the other two which is compensated by higher rpms, but the V-1710 ran at higher boosts towards the end of the war.
The centrifugal compressor works very much the same as a mechanical supercharger as it does in a turbocharger. The conditions may vary some what, but they still operate the same.
And similar to steam turbines.
His gas turbine design, apparently, did not work.
As for testing the turbo with a "single combustion chamber", was it a single cylinder engine? Did the compressor feed the engine, or was the output just measured?
An aside, when Rolls-Royce took over developing the Whittle engine from Rover, they employed a Vulture to drive the compressor for testing.
It seems that nothing major was changed on the first couple of turbojets they made without input from Power Jets.
As Moss had been working on turbochargers since WWI, not sure how much combustion chamber knowledge he had, or how much of it was current.
wuzak
Captain
I would note that the Merlin XII had +0psi boost at around 25,000ft when climbing and around 28,000ft when flat out.
http://www.spitfireperformance.com/Spitfire_II_P-7280_level-speed.jpg
The Merlin 25 had +0.6psi boost at 28,000ft on climb and +1.2psi boost at 28,000ft flat out.
http://www.spitfireperformance.com/Spitfire_II_P-7280_level-speed.jpg
The Merlin 25 had +0.6psi boost at 28,000ft on climb and +1.2psi boost at 28,000ft flat out.
- Thread starter
- #109
So this is why they were perceived as being overweight?
From what I grasp, Westinghouse didn't really branch off it's steam and gas-turbine divisions, and steam turbine designers would often make periodic modifications and develop several different designs, each with different mods rather than more elaborate modifications.
With gas-turbines they basically did well early on and got cocky with their success and didn't do adequate research into how to develop newer designs and basically tried to scale-up with what with what worked before.
That's real interesting...
This sounds like something Edgar Buckingham proposed...
Did this data make it across the pond?
The efficiency was better and they were bigger right?
Last edited:
- Thread starter
- #110
I'm not so confident of this, I suppose you could argue that one advantage we had was that we had two years to sit back and watch what was happening.
One could also argue that our political stance to avoid conflict would have been an advantage, but FDR probably wanted to be involved off the bat, but couldn't get the public and Congress to do what he wanted.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
If the U.S. had gone to war in 1939, her inventory would have been on a par with the Axis nations.
The IJN's front-line fighter was the A5M, the IJA's front line fighter was the KI-27.
Germany had the Bf109D and some He112Bs
The U.S. had the P-36, F3F and F2A.
And entering the war two years earlier would have been no different on the war-time ramp-up of U.S. industry and it would have accelerated aircraft development along the same path as it took historically.
The IJN's front-line fighter was the A5M, the IJA's front line fighter was the KI-27.
Germany had the Bf109D and some He112Bs
The U.S. had the P-36, F3F and F2A.
And entering the war two years earlier would have been no different on the war-time ramp-up of U.S. industry and it would have accelerated aircraft development along the same path as it took historically.
Shortround6
Major General
Some people believe the US sitting back, fat dumb and happy until Dec 7th 1941 at which point, angered and aroused, the US swung into action.
This is totally false.
The US, from a production standpoint had been gearing up since at least 1939, in large part due orders from France and England (England had ordered the Lockheed Hudson in 1938). Ford was making P & W R-2800s in a government paid for factory several month before Pearl Harbor.
The US Navy had been getting larger and larger appropriations and starting construction of new ships and equipment.
There had a been a 40% increase in naval spending from 1935 to 36, another 8% from 36 to 37, held steady in 1938 and then jumped 27% in 1938 and then jumped 68% on 1940 over 1939. Total increase in spending had jumped over 300% from 1935, 1941 saw almost a 400% increase over 1940 and please remember that these appropriations are voted on before the start of the Gov fiscal year so the 1941 appropriation was made months before Pearl Harbor.
Several tank production lines had been started in locomotive factories well before Pearl harbor. The M3 Stuart started production in March of 1941, April of 1941 saw pilot models of M3 Grant built in the Detroit tank arsenal (new factory started construction in 1940), American Locomotive, and Baldwin Locomotive. By July of 1941 all three plants were making production versions. (Pilot tank models are often made of mild steel and not armor).
US response in 1942 was not the result of anger or a shift in will (although that certainly helped) but the result of several years of building up the infrastructure and numbers. How much sooner some of these things could have been done I don't know.
This is totally false.
The US, from a production standpoint had been gearing up since at least 1939, in large part due orders from France and England (England had ordered the Lockheed Hudson in 1938). Ford was making P & W R-2800s in a government paid for factory several month before Pearl Harbor.
The US Navy had been getting larger and larger appropriations and starting construction of new ships and equipment.
There had a been a 40% increase in naval spending from 1935 to 36, another 8% from 36 to 37, held steady in 1938 and then jumped 27% in 1938 and then jumped 68% on 1940 over 1939. Total increase in spending had jumped over 300% from 1935, 1941 saw almost a 400% increase over 1940 and please remember that these appropriations are voted on before the start of the Gov fiscal year so the 1941 appropriation was made months before Pearl Harbor.
Several tank production lines had been started in locomotive factories well before Pearl harbor. The M3 Stuart started production in March of 1941, April of 1941 saw pilot models of M3 Grant built in the Detroit tank arsenal (new factory started construction in 1940), American Locomotive, and Baldwin Locomotive. By July of 1941 all three plants were making production versions. (Pilot tank models are often made of mild steel and not armor).
US response in 1942 was not the result of anger or a shift in will (although that certainly helped) but the result of several years of building up the infrastructure and numbers. How much sooner some of these things could have been done I don't know.
parsifal
Colonel
Have to say I disagree that the US was ready for war in 1939 and that the preparations leading up to 12/41 was witnessing a rapid preparation for war. In fact the US started in 1939 and this situation worsened in the lead up to war. It made some critical decisions in 1940 and 1941 that ultimately saved them and paid dividends in the latter part of the war, but at the beginning they were in deep trouble and possessed limited power outside continental US.
I will concentrate on the Navy purely because that is the subject I know the most about . USN entered the war with nearly 200 DDs, many of them ex-WWI relics. However they lacked the manpower to put more than 50 to sea, and worse the training establishments had been so run down that it would take nearly four years to rectify that .
The USN went to war with just 3-6 BBs ready for sea (depending on who you believe). As the situation worsened, many of the BBs were rapidly refitted and made ready for sea, with reduced crews, but at least they were fit for sea. These BBs had not been properly modernised and had they been forced to sea would have been an overall liability. the Japanese Dreadnoughts had been extensively modernised in the thirties and would have torn the US battlefleet fleet to pieces had it met on the field of battle.
Newer BBS were on the way, that in general would turn that situation around, but initially these BBs (like the sth Dakota) were not ready to go to sea. They would not be ready until the latter part of 1942.
The carriers were the most ready, but the air groups were substandard. buffaloes were meant to be the replacement for the F3Fs, and the F3Fs were basically clapped out. Air Groups were short of pilots and a/c.
ASW tactics were poor and the submarine fleet whilst large, was poorly trained, and with ranges unable to reach across the pacific. Torpedoes were defective.
Critically the merchant marine entered the war far too small to meet even the domestic needs . The US was subsidised by the British controlled merchant marines to the tune of roughly 4million tons and nearly half her required tanker fleets. About 1 million tons of new construction was added up to 12/41, but more than 2million tons was reflagged to British or allied colours, so that they could continue to trade with the allies in the so called "declared areas". The US entered the war completely unable to project her land power because of the shipping shortages , and this situation remained until well into 1943. In the PTO the US had the lift capacity to project roughly 1 div after 1941, whilst in the ETO by accepting short term shortages elsewhere, the USN was able to land and support 4 div equivalents in Torch but only just.
Moreover this situation was initially totally ignored by the USN. Uncle Ernie very nearly lost the war by his stubborn refusal to implement proper training and doctrines, as well as equipment for ASW operations, despite all the lessons unfolding in the Atlantic in 1940 and 1941. He refused to adopt convoy for about 4 months because he saw it as a defensive measure. Refused to listen to the RN on any of these matters. He in fact blamed convoys for the losses being sustained.
The army was similar to the navy in that it was short of manpower and even shorter on training capacity. in 1939 it nominally had 12 divs, but not one of them was combat ready. This remained the situation until well into 1943 for most of them, and in reality the USGF never solved its trained manpower problems.
The US concentrated on getting capital items built and ultimately this paid off. They initiated a massive shipbuilding program. set up huge factories to churn out tanks guns and planes. this ultimately paid dividends, but throughout 1942, the US was a nation fighting but unready for war
I will concentrate on the Navy purely because that is the subject I know the most about . USN entered the war with nearly 200 DDs, many of them ex-WWI relics. However they lacked the manpower to put more than 50 to sea, and worse the training establishments had been so run down that it would take nearly four years to rectify that .
The USN went to war with just 3-6 BBs ready for sea (depending on who you believe). As the situation worsened, many of the BBs were rapidly refitted and made ready for sea, with reduced crews, but at least they were fit for sea. These BBs had not been properly modernised and had they been forced to sea would have been an overall liability. the Japanese Dreadnoughts had been extensively modernised in the thirties and would have torn the US battlefleet fleet to pieces had it met on the field of battle.
Newer BBS were on the way, that in general would turn that situation around, but initially these BBs (like the sth Dakota) were not ready to go to sea. They would not be ready until the latter part of 1942.
The carriers were the most ready, but the air groups were substandard. buffaloes were meant to be the replacement for the F3Fs, and the F3Fs were basically clapped out. Air Groups were short of pilots and a/c.
ASW tactics were poor and the submarine fleet whilst large, was poorly trained, and with ranges unable to reach across the pacific. Torpedoes were defective.
Critically the merchant marine entered the war far too small to meet even the domestic needs . The US was subsidised by the British controlled merchant marines to the tune of roughly 4million tons and nearly half her required tanker fleets. About 1 million tons of new construction was added up to 12/41, but more than 2million tons was reflagged to British or allied colours, so that they could continue to trade with the allies in the so called "declared areas". The US entered the war completely unable to project her land power because of the shipping shortages , and this situation remained until well into 1943. In the PTO the US had the lift capacity to project roughly 1 div after 1941, whilst in the ETO by accepting short term shortages elsewhere, the USN was able to land and support 4 div equivalents in Torch but only just.
Moreover this situation was initially totally ignored by the USN. Uncle Ernie very nearly lost the war by his stubborn refusal to implement proper training and doctrines, as well as equipment for ASW operations, despite all the lessons unfolding in the Atlantic in 1940 and 1941. He refused to adopt convoy for about 4 months because he saw it as a defensive measure. Refused to listen to the RN on any of these matters. He in fact blamed convoys for the losses being sustained.
The army was similar to the navy in that it was short of manpower and even shorter on training capacity. in 1939 it nominally had 12 divs, but not one of them was combat ready. This remained the situation until well into 1943 for most of them, and in reality the USGF never solved its trained manpower problems.
The US concentrated on getting capital items built and ultimately this paid off. They initiated a massive shipbuilding program. set up huge factories to churn out tanks guns and planes. this ultimately paid dividends, but throughout 1942, the US was a nation fighting but unready for war
Shortround6
Major General
The US was, as you note, far from ready for war in 1939. But it also did not wait until Dec 7th 1941 to start getting ready.
It was 3-5 years behind France and England depending on the criteria selected and the particular field or items you are looking at.
How much difference it would have made to be actually at war I don't know.
Being at war certainly does not eliminate bad decisions. Like sending the HMS Courageous out on an offensive anti-submarine patrol in Sept 1939 with only 4 accompanying destroyers.
The US started selective service (the Draft) in Oct 1940 with first men selected showing up in Nov 1940. Over a year before Pearl Harbor but over a year behind the the start of the war in Europe.
More manpower would have been available sooner had the US actually been at war. However the ability to train (or even house) many more men is certainly subject to question let alone arm them.
The US would certainly have taken time to ramp up and not been able to go into action in 1939/40 to any real extent but some speeding up of certain things was certainly possible.
It was 3-5 years behind France and England depending on the criteria selected and the particular field or items you are looking at.
How much difference it would have made to be actually at war I don't know.
Being at war certainly does not eliminate bad decisions. Like sending the HMS Courageous out on an offensive anti-submarine patrol in Sept 1939 with only 4 accompanying destroyers.
The US started selective service (the Draft) in Oct 1940 with first men selected showing up in Nov 1940. Over a year before Pearl Harbor but over a year behind the the start of the war in Europe.
More manpower would have been available sooner had the US actually been at war. However the ability to train (or even house) many more men is certainly subject to question let alone arm them.
The US would certainly have taken time to ramp up and not been able to go into action in 1939/40 to any real extent but some speeding up of certain things was certainly possible.
Glider
Captain
This paper may be of interest as it shows the increase by year of the US Army. Its notable that the increases were fairly minor up to 1940 and its only from 1941 where it really takes off. It should also be remembered that the figures include the USAAF until 1948, when the USAAF was about 40% of the US Army.
1938 - 183,455
1939 - 187,893
1940 - 264,118
1941 - 1,588,032
1942 - 3,203,819
A number of ears ago I attended lecture at the RUSI on the growth and effectiveness of the US Army in WW2 and the lecturer in his summing up described it as the best citizens army ever fielded. This phenomenal growth had advantages and disadvantages.
Disadvantages included -
The following is the paper with the numbers
View: https://drive.google.com/file/d/0B0kkOiAWUCUGLWZQTDItRVJwUzA/edit
1938 - 183,455
1939 - 187,893
1940 - 264,118
1941 - 1,588,032
1942 - 3,203,819
A number of ears ago I attended lecture at the RUSI on the growth and effectiveness of the US Army in WW2 and the lecturer in his summing up described it as the best citizens army ever fielded. This phenomenal growth had advantages and disadvantages.
Disadvantages included -
- A total lack of experience in the officer class due to the expansion and a lack of experience as pre war exercises were totally unrealistic. Also the deployments tended to be fairly local and officers were not encouraged to use initiative
- A tendency to do things by the book and officers were not encouraged to do things on their own.
- The US Army had to learn quickly and leaders had to rely on the natural skills of themselves and the people around them. It wasn't unusual to see officers listening to suggestions from junior ranks. The pre war officers who didn't show flexibility were simply overwhelmed and could be given admin posts where they could do little harm in the front line whilst still doing a worthwhile job helping to handle the expansion.
- The intelligence, experience and education of the average soldier of any rank was much higher than any other army which showed itself in the flexibility of the troops themselves. If a different or better way was identified to do something the US were more willing to try. This in turn helped the spread of best practice as literally everyone knew that they were inexperienced.
- The United States generally were more technically oriented than any other nation
The following is the paper with the numbers
View: https://drive.google.com/file/d/0B0kkOiAWUCUGLWZQTDItRVJwUzA/edit
- Thread starter
- #116
Shortround6
Major General
Initiative is a double edged sword.
Too little means opportunities not grasped or difficulties not overcome in time.
Too much means units charging off in different directions without the higher command Knowing what is going on or even where some units are.
Which makes it very difficult to organize supply/back up, coordinate supporting attacks or artillery fire missions.
It was also a time a very rapid advancement in communications, Numbers of Radios increased tremendously and the ability of lower echelon units to have radios went up substantially.
Too little means opportunities not grasped or difficulties not overcome in time.
Too much means units charging off in different directions without the higher command Knowing what is going on or even where some units are.
Which makes it very difficult to organize supply/back up, coordinate supporting attacks or artillery fire missions.
It was also a time a very rapid advancement in communications, Numbers of Radios increased tremendously and the ability of lower echelon units to have radios went up substantially.
Glider
Captain
[/QUOTE]
Officers trained before the war had to do things by the book. This was pretty endemic in all the US pre war forces and carried on into the first years of combat. When these people were weeded out then the forces could really develop.
This ability in most cases of officers listening to more junior ranks was the reason he called it a citizens army.
buffnut453
Captain
Officers trained before the war had to do things by the book. This was pretty endemic in all the US pre war forces and carried on into the first years of combat. When these people were weeded out then the forces could really develop.
This ability in most cases of officers listening to more junior ranks was the reason he called it a citizens army.[/QUOTE]
I'm struggling to understand how the US Army was different from many other armies in the aspects you identified. For example, the British Army wasn't particularly large in 1939 and was an all-volunteer force. Compare that with the size and complement in 1944-45, and there's no comparison. So why was the US Army exceptional?
This ability in most cases of officers listening to more junior ranks was the reason he called it a citizens army.[/QUOTE]
I'm struggling to understand how the US Army was different from many other armies in the aspects you identified. For example, the British Army wasn't particularly large in 1939 and was an all-volunteer force. Compare that with the size and complement in 1944-45, and there's no comparison. So why was the US Army exceptional?
Glider
Captain
I'm struggling to understand how the US Army was different from many other armies in the aspects you identified. For example, the British Army wasn't particularly large in 1939 and was an all-volunteer force. Compare that with the size and complement in 1944-45, and there's no comparison. So why was the US Army exceptional?[/QUOTE]
The British Army was a lot bigger than the US Army which in 1938 had a smaller army than Portugal. Its army had always been deployed across the world and in these overseas areas officers were encouraged to show initiative and go on expeditions.
The growth was much greater in the USA
In 1939 the US Army had approx. 184,000 men including the USAAF and peaked at approx. 8,300,00
In August 1939 the British Army had approx. 630,000 men (including the territorials) excluding the RAF and peaked in 1945 at approx. 2,900,000
In percentage terms the US Army increased massively more than the British Army peaking at about 45 times the size at the start of the war. The British increased by approx. 4.6 times a tenth of the growth of the US Army.
