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Estimating the performance of supercharged piston aero engines


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#101 Vanishing Point

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Posted 29 September 2011 - 12:40

If the RAF had something like a Griffon Spitfire ready for the BoB it is highly likely that Adolf would have been aware of it and would have delayed the start of WW2 until he had something similar.

I really don't think you can speculate on history like you do.

I sometimes think that if America had not become independent of England (and had remained associated in a Commonwealth arrangement like Oz et al.) that probably WW1 and WW2 and maybe even the Civil War would not have happened.

But - who knows? - it may have started a new "timeline" where different (and possibly, far worse) wars occurred. And the same may have happened with Grffon Spits etc. and WW2 - delaying the war may have allowed Adolf to have a atom bomb available.

You have probably seen enough Star Trek to know that it doesn't pay to interfere with timelines.


As you'll see I sometimes think that the movies have got it right. :clap:

2.22-2.44


But I think Hitler and Goering probably already had an idea of what they were (would/should) have been up against from seeing what Mitchell and Rolls managed to do to the opposition 10 years earlier during the Schneider competition.The only surprise they probably got was wondering how it was that the Luftwaffe only found itself faced with a force made up of Hurricanes when they invaded France and that's probably why they got a bit of a shock a bit later during the evacuation of Dinkirk and in the Battle of Britain.It's just that by my timeline they would have got a bit more than they bargained for when they went for France at the beginning considering how much better the Mk XIV Spit was than the Schneider winners.

I think that any suggestion,that Mitchell and Rolls and all of their respective design teams wouldn't/couldn't have come up with the design of the Mk XIV,at the beginning,if it was a plane with that type of performance that had been ordered and specced by those doing the ordering from the start,is an insult to their intelligence.However there's no evidence which would show that the invasion of Poland and then France would have been 'delayed' by Hitler on the basis of the possible strength or otherwise of the RAF.Such a change in the balance of power within the repective air forces probably wouldn't have made any difference to Germany's ability to develop nuclear weapons either.

Edited by Vanishing Point, 29 September 2011 - 12:44.


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#102 Vanishing Point

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Posted 29 September 2011 - 13:02

Hurricanes shot down more enemy aircraft than Spitfires did during the BOB.
Nough said.
The best WW2 aero engines were the Bristol sleeve valve engines.
The Vickers Wellington was the best bomber (Sir Barnes Wallis, also designed the Lancaster), fitted with Bristol sleeve valve engines, it held the line for YEARS before the Americans came in with their B17s and Liberators.
Both these aircraft carried only a small bomb load, smaller than the twin engined Wellington x.
The American poppet valved radials were unreliable and underpowered and four were needed compared to two British Bristols.
The only reason that bomber Command and the Wellington are not celebrated to the same level or higher than the Spitfire and Fighter Command during the same period, is because of bomber Harris and his carpet bombing campaign, that left the American 8th mostly blowing costly holes in the European country side. To get within a half mile of target was a miracle.
The Lancaster (after the Stirling-Bristols and Halifax) were true heavy bombers not medium bombers like the B17.
Later in the war the Mosquito bomber version carried the same load as a B17. (design superiority)

The B36 of post war SAC with six American radials (and 4 jet engines) suffered at least one radial engine strip or change on every long range mission.
The jets were of course of British origin built under a criminal agreement after the war and one of the things that killed the British Empire.

I love the stated use of American fighters against Japanese Kamakasi's, most of the Kamakasi's were pilots with less than five hours and sometimes flying unarmed trainers. Still its all part of the dream I suppose.
Bomber Command from 1939 to 1943 was bombing Europe on its own with a loss rate as high as four in five crews.
Please dont tell me American engines were best, they were not.



No one is saying that 'American engines are/were best'.Certainly not me.What I'm saying is that the Griffon was a better engine for the job of powering an air superiority fighter than the Merlin and the Spitfire was a better plane than the Hurricane.The only reason that the Hurricanes managed to shoot down more planes than Spitfires is because there were more Hurricanes and it was the Spitfires that did most of the fighter v fighter role.What happened in France shows the actual results of a Hurricane equipped air force v Me 109.However where I am saying that 'American was best' is in the comparison of the Typhoon/Tempest and the T bolt ( Sabre/Vulture v 2800).

#103 mariner

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Posted 29 September 2011 - 15:04

Slightly OT but for anybody who lives in, or schedules vsits to, the UK you can apparently , have a technical tour of the Battle of Britian Flight workshops at Coningsby ( Linclonshire) to see the aircraft and engines under discusion close up.

http://www.lincolnsh...r/85741.article

I do have to say that the technical tours are NOT mentioned on the actual BBMF website but maybe that is too general.

#104 mariner

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Posted 29 September 2011 - 15:12

The Vickers Wellington was the best bomber (Sir Barnes Wallis, also designed the Lancaster), fitted with Bristol sleeve valve engines, it held the line for YEARS before the Americans came in with their B17s and Liberators.



24Gerrard , I think that if you check you will find that Roy Chadwick, not Barnes Wallis designed the Lancaster. Barnes Wallis was a remarkable engineer but credit forthe Lancaster belongs to Roy Chadwick

#105 Vanishing Point

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Posted 29 September 2011 - 15:32

24Gerrard , I think that if you check you will find that Roy Chadwick, not Barnes Wallis designed the Lancaster. Barnes Wallis was a remarkable engineer but credit forthe Lancaster belongs to Roy Chadwick


Even more relevant to the topic not only did Avro produce probably the best bomber of the war,like in the best fighters of the war,they also knew that V12 power not X or H 24 power was the best way to power it.No surprise either they then used the same engineering logic when the Griffon was chosen to power the following developments of the Lanc.Having said that the radial powered Fortress,together with it's build strength,did show the same type of survivability as the T bolt in the case of damage that would probably have brought down a Lancaster.

Edited by Vanishing Point, 29 September 2011 - 15:38.


#106 cheapracer

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Posted 29 September 2011 - 16:02

I know stuff all about planes but I have stood on a MIG or 2 ;) ..............

http://forums.autosp...w...6714&hl=MIG

Many pictures here if you missed the link

http://s784.photobuc...relexomilitary/

Edited by cheapracer, 29 September 2011 - 16:07.


#107 Wuzak

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Posted 30 September 2011 - 04:03

In 1935 Allison were busy developing the V-1710, to be rated at 1000hp at that time. The USAAC was looking for a 2000hp engine to power its long range bombers, which were to become the Boeing XLBR-1 (later renamed XB-15) and Douglas XLBR-2 (later XB-19), so they approached Allison with the idea of doubling up the V-1710 into the X-3420. The engine was to have 4 V-1710s on a new crankcase, with a single crankshaft using master and slave rods.

Allison mocked up the X-3420 and estimated its performance as 1600hp @ 2400rpm, claiming that the rpm and power was limited due to the master and link rod arrangement.

Meanwhile, over in the UK Rolls-Royce were starting development of the Vulture, aiming for 2000hp and 3200rpm. It also used a master and slave rod arrangement. The main difference is the angles at which the bank angles were set - the banks on the RR engine were equally disposed around the crank, whereas the Allison had 90° between the centre banks, and maintained the 60° between the banks on each side. No doubt that was to use as much common componentry as possible, especially on the induction side where the direct fuel injection and manifold system beng developed on the V-1710 was to be used.

Just wondering if the equal spacing of the cylinder banks is better for the balance of the X24 engine than the 60°-90°-60°-150° layout of the Allison?

Allison, of course, was having a hard enough time getting the V-1710 going with their limited resources and even more limited funding. So it may have proved difficult to them to design the X-3420 concurrently with the V-1710. In the end they proposed that they build the twin crank V-3420 (basically two V-1710s mounted on a single crankcase), which shared even more components than the X-3420.


#108 gruntguru

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Posted 30 September 2011 - 10:49

Where's the logic in saying that it would have needed to be such a different aircraft . . .

I ddn't say that it needed to be different, only that it would have been different.

. . . when it was proven that a re engineered and developed Spitfire could handle the Griffon's power adequately in service.

Mitchell (and everyone else) certainly didn't know that in 1933. The evolution in Spitfire power was a steady one and a lot of developmental tweaks (often major modifications) were required along the way. The whole journey was a learning process expanding the known boundaries.

#109 gruntguru

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Posted 30 September 2011 - 10:54

But the issue of numbers being better than superiority is something like the logic used on the ground with tanks during WW2.The German gunners said that they ran out of shells before the allies ran out of Shermans.However each of those Shermans contained a crew and in the case of the fall of France during the beginning of WW2 the Luftwaffe didn't run out of planes or ammunition before it had taken out the RAF's Hurricanes first and those casualties in pilots had to be replaced and was one of the reasons why the Battle of Britain and therefore the war was almost lost.

It wasn't a case of Britain trying to win a battle of numbers - it was a case of being massively outnumbered and on many occaisions desperation to get a semblance of resistance into the air. If they had followed your suggestion of converting Hurricane production to Spits at the beginning of the BoB they would have lost the War.

#110 Vanishing Point

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Posted 30 September 2011 - 12:00

I ddn't say that it needed to be different, only that it would have been different.


Mitchell (and everyone else) certainly didn't know that in 1933. The evolution in Spitfire power was a steady one and a lot of developmental tweaks (often major modifications) were required along the way. The whole journey was a learning process expanding the known boundaries.



The 'evolution' of Spitfire design was actually just the natural progression which took place because of the inherent inferiorities built into the early marks caused by the flaws and retro grade thinking by those doing the ordering and speccing.If the original government order and spec had called for something with the performance of the Mk XIV then it's probably a Mk XIV that would have got designed and built from the outset instead of taking the small steps approach needed to turn the inferior early marks,with their inferior power outputs,into what was needed from the start.The 'known boundaries',in the 1930's,were actually a lot more advanced than the designers and engineers were,and obviously still are,given credit for.

My view of what happened was simply that the government at the time couldn't get their heads around what would have been possible if the aircraft manufacturing industry,in this case Supermarine and Rolls,had been given the tall order of a plane with the performance of the XIV from the start.In which case those 'tweaks' and 'modifications' wouldn't have been required because they'd already have taken place on the drawing board and on the engine dyno at the design stage before the plane was needed for service just as was the case with the early Merlin powered versions.

In this case the power required to meet the better spec would just have meant building on the foundations of using an engine with the type of capacity of the previous R instead of the Merlin and the structural design of the Spitfire would have needed to reflect the use of that type of power unit at the outset instead of later by modification.Everything about the quick progression at Rolls from Merlin to Griffon and the way in which the basic design of the Spitfire contained the capability to be re engineered to use that power unit shows that the Mk XIV was the plane that the Spitfire would/should have been at the outset.

If only Mitchell could have been around to tell everyone that's what he really had in mind when he designed it which is my hypothesis.

#111 Vanishing Point

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Posted 30 September 2011 - 12:14

It wasn't a case of Britain trying to win a battle of numbers - it was a case of being massively outnumbered and on many occaisions desperation to get a semblance of resistance into the air. If they had followed your suggestion of converting Hurricane production to Spits at the beginning of the BoB they would have lost the War.



I think you've forgot to factor in that Hurricane production would have been converted to Spitfire production at the original outset of production of the Spitfire not at 'the beginning of the BoB'.

The result of the loss of the war only applies if you subscribe to the theory that a force made up of similar numbers Mk XIV Griffon Spits wouldn't have provided a much better kill ratio against 109's than one made up of Hurricanes and a few early mk Merlin Spits and if the Battle for France had relied on Griffon Spits instead of Hurricanes.

Edited by Vanishing Point, 30 September 2011 - 12:14.


#112 Wuzak

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Posted 30 September 2011 - 12:50

Sorry VP, but if the Ministry for Aircraft Production had in 1934/35 issued a request for a 450mph aircraft which could climb at over 5000ft/min with a ceiling over 40,000ft the aircraft manufacturers would have laughed at them.

FWIW the Spitfire was the fastest aircraft in the world before WW2. And if it wasn't it was only just behind the Messerschmitt Bf109E.

Also, the spec that the P-38 and P-39 were built to asked for a top speed of 400mph. This was later than the Spitfire spec, but before WW2 when the spec was issued. Lockheed chose a twin engine a/c because it was the only way they could see to meet the performance requirments with the engines available. The P-39 wasn't really anywhere near the performance requirements/predictions when it flew as a prototype.

The Tornado/Typhoon spec also called for a top speed of over 400mph. Hawker predicted 460mph for the Typhoon - and barely managed 400mph.

The feasibility of producing the performance of late WW2 aircraft and engines before the BoB was low, if not non-existant. If it was feasible it would have happened - on both sides.

#113 Wuzak

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Posted 30 September 2011 - 12:56

I think you've forgot to factor in that Hurricane production would have been converted to Spitfire production at the original outset of production of the Spitfire not at 'the beginning of the BoB'.

The result of the loss of the war only applies if you subscribe to the theory that a force made up of similar numbers Mk XIV Griffon Spits wouldn't have provided a much better kill ratio against 109's than one made up of Hurricanes and a few early mk Merlin Spits and if the Battle for France had relied on Griffon Spits instead of Hurricanes.


Hurricane production was in full swing before Spitfire production got underway.

Even with these two programs up and running before WW2 the British went to the US to procure P-40s and to NAA to procure a second production line of P-40s (which led to the P-51). They even gave away some of their best technologies (radar, the Whittle engine) for US help. They needed aircraft, and they needed them now.

Setting up the Hawker production line for Supermarine Spitfires would have cost a year, at least, in Hurricane production and have produced fewer aircraft in the allotted time.



#114 Vanishing Point

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Posted 30 September 2011 - 13:22

Sorry VP, but if the Ministry for Aircraft Production had in 1934/35 issued a request for a 450mph aircraft which could climb at over 5000ft/min with a ceiling over 40,000ft the aircraft manufacturers would have laughed at them.

FWIW the Spitfire was the fastest aircraft in the world before WW2. And if it wasn't it was only just behind the Messerschmitt Bf109E.

Also, the spec that the P-38 and P-39 were built to asked for a top speed of 400mph. This was later than the Spitfire spec, but before WW2 when the spec was issued. Lockheed chose a twin engine a/c because it was the only way they could see to meet the performance requirments with the engines available. The P-39 wasn't really anywhere near the performance requirements/predictions when it flew as a prototype.

The Tornado/Typhoon spec also called for a top speed of over 400mph. Hawker predicted 460mph for the Typhoon - and barely managed 400mph.

The feasibility of producing the performance of late WW2 aircraft and engines before the BoB was low, if not non-existant. If it was feasible it would have happened - on both sides.


There's a difference between fastest 'production fighter' for 1940 and fastest 'aircraft'.The latter comparison was already into the 400 mph mark with the Schneider planes 10 years before WW 2 started.The difficult bit was getting the performance of the former,using the years in between,better than the latter.The use of a 27 Litre engine,designed with private funding, instead of a clean sheet carte blanche 37 Litre one built with unlimited government funding was a retrograde step.If the latter type of engine had been developed much earlier during those 10 years between the Schneider R type and the eventual Griffon of the early 1940's the rest would probably all have followed on Mitchell's drawing boards.

But there still seems to be some inability to understand that better superior planes,in this case,would have beaten the idea of more inferior ones and in this case history shows that one battle was lost through th idea of using Hurricanes and one even more important battle 'almost' was because of it.Whereas a lot less Hurricanes but enough far superior Spitfires than the ones used probably could have stopped the Luftwaffe far sooner.


#115 WPT

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Posted 30 September 2011 - 16:48

Wuzak, thanks for the info on the RM17SM RR test engine. Think RR had a design for a 3-speed blower drive for the Merlin that fit in the space of the 2-speed drive. Don't know if any 3-speeds were built or not. Too bad a '17' with a 3-speed blower was never tested in something like the lightweight Mustang.
Prototype P-39s (think there were six made) came close to 390MPH, but these planes were equiped with turbos. Think GB ordered 39s based on the prototype's performance, but the USAAC deleted the turbo for their order (and so no turbo for GB). Of course, without the turbos, top speed way down. GB not happy with the slow '39' and returned the order. GB also ordered P-38s for ground attack role. They deleted the turbos and the counter-rotating props (so only one engine needed in inventory). Performance way off and they returned these planes also. GB gave the OK to NAA to build the P-51 before BoB. One wonders if they would have ordered the plane if they knew BoB lessons. NAA tests showed a top speed of 390MPH. GB thought when the production planes got to GB they might be up to 70MPH slower. GB test of a production plane to their specs gave 383MPH, but poor performance above ~18,000 feet. GB kept these planes and found a mission for them.
Know BoB was a near thing. Think I would be thankful for what GB did have; two decent fighters, pilots to fly them, radar, Royal Navy, etc. Thankful the Germans did not have enough subs and for their mistakes (stopping the panzers before Dunkirk, invading Russia, etc.). WPT

#116 Wuzak

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Posted 30 September 2011 - 22:25

I don't believe that the Merlin was ever going to get a 3 speed. 100 series Griffons ofr Spitefuls and Seafangs did get the three speed drive.

A curiousity about the Merlin and Griffon was that the former was chosen to be made into an engine for commercial aircraft, but the latter was not.

There is some doubt on the ability of the XP-39 to match its estimated top speed of 390mph. The XP-39 had a very poor intercooler arrangement with the air to air intercooler behind the pilot with a large scoop on the left hand side of the fuselage. It was very draggy. The turbo used was also unreliable and the XP-39 lacked required military equipment - armour, self sealing fuel tanks, armaments. And it was somewhat heavier than it needed to be.

NACA did some wind tunnel testing and made some recommendations - one was to ditch the turbo, the intercooler and its ducting.

Britain and France both ordered P-38s specified with the same engines as the P-40s they had on order at the time. Plus they wanted them optomised for the altitudes they were expected to fight. That is single stage supercharged and both rotating in the same direction. Also they were wary of delays in turbocharger deliveries. Otherwise I believe the aircraft were to P-38D specification. The British experience with the Lightning was poor. But the USAAF also deemed the P-38D as not being combat ready.

#117 bigleagueslider

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Posted 30 September 2011 - 23:48

Just spent a half hour reading through the posts. Good stuff. It makes for a great discussion when you have such knowledgeable participants.

Regarding Merlin development, I have a great paperback book I bought from the RR Heritage Trust that describes all of the design changes to the Merlin during the war years in excruciating detail. If you're a Merlin fan, I highly recommend it. It's titled "The Merlin in Perspective- the combat years".

http://www.rolls-roy...e/publications/

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#118 Vanishing Point

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Posted 01 October 2011 - 12:09

I don't believe that the Merlin was ever going to get a 3 speed. 100 series Griffons ofr Spitefuls and Seafangs did get the three speed drive.

A curiousity about the Merlin and Griffon was that the former was chosen to be made into an engine for commercial aircraft, but the latter was not.

There is some doubt on the ability of the XP-39 to match its estimated top speed of 390mph. The XP-39 had a very poor intercooler arrangement with the air to air intercooler behind the pilot with a large scoop on the left hand side of the fuselage. It was very draggy. The turbo used was also unreliable and the XP-39 lacked required military equipment - armour, self sealing fuel tanks, armaments. And it was somewhat heavier than it needed to be.

NACA did some wind tunnel testing and made some recommendations - one was to ditch the turbo, the intercooler and its ducting.

Britain and France both ordered P-38s specified with the same engines as the P-40s they had on order at the time. Plus they wanted them optomised for the altitudes they were expected to fight. That is single stage supercharged and both rotating in the same direction. Also they were wary of delays in turbocharger deliveries. Otherwise I believe the aircraft were to P-38D specification. The British experience with the Lightning was poor. But the USAAF also deemed the P-38D as not being combat ready.


The whole issue of the lack of development in the US aircraft industry should have been noticed at the enquiry stage,let alone placing orders and then finding out that they weren't good enough in service,because of what were obviously flawed designs with not enough development behind them.It seems to me to just show yet more confusion and lack of knowledge,about the products they were looking for,within the British and US government/s where they should have been placing greater demands on the aircraft manufacturers at an earlier stage before the war and providing the funding to match.


Both the Merlin or the Griffon weren't really the ideal choice for civil aviation applications.That really needed something that could provide more power for less stress than a 27 or 37 Litre V 12 fighter based engine could provide even allowing for the fact that they were adaptable to the heavy/bomber role.The idea of the Breda BZ .308,using four Bristol Centaurus engines,seemed much better than the Tudor in that regard.The question is why didn't Bristol take that design over from Breda when the issue of it's obvious superiority over the Tudor and even the Constellation and it's resulting cancellation caused by 'war reperations' demands by the ex allied powers civil aviation producers.Yet again it seems like the British aviation industry shot itself in the foot by handing a competitive advantage back to America by building the Brabazon where it could have used a better more practical design.




#119 24gerrard

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Posted 01 October 2011 - 13:43

24Gerrard , I think that if you check you will find that Roy Chadwick, not Barnes Wallis designed the Lancaster. Barnes Wallis was a remarkable engineer but credit forthe Lancaster belongs to Roy Chadwick


Sorry my bad, I was thinking of the work Barnes Wallis did at Vickers on the Lancaster and the armament developments for the aircraft.

Roy Chadwick deserves full credit for the Manchester design and the development of that underpowered aircraft into the Lancaster.

The Wellington was designed by Barnes and was the main bomber for the RAF right through the war.
It is a shame there are no flying ones left.

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#120 24gerrard

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Posted 01 October 2011 - 13:44

The whole issue of the lack of development in the US aircraft industry should have been noticed at the enquiry stage,let alone placing orders and then finding out that they weren't good enough in service,because of what were obviously flawed designs with not enough development behind them.It seems to me to just show yet more confusion and lack of knowledge,about the products they were looking for,within the British and US government/s where they should have been placing greater demands on the aircraft manufacturers at an earlier stage before the war and providing the funding to match.


Both the Merlin or the Griffon weren't really the ideal choice for civil aviation applications.That really needed something that could provide more power for less stress than a 27 or 37 Litre V 12 fighter based engine could provide even allowing for the fact that they were adaptable to the heavy/bomber role.The idea of the Breda BZ .308,using four Bristol Centaurus engines,seemed much better than the Tudor in that regard.The question is why didn't Bristol take that design over from Breda when the issue of it's obvious superiority over the Tudor and even the Constellation and it's resulting cancellation caused by 'war reperations' demands by the ex allied powers civil aviation producers.Yet again it seems like the British aviation industry shot itself in the foot by handing a competitive advantage back to America by building the Brabazon where it could have used a better more practical design.


It was the criminal bankers just like today.

#121 Vanishing Point

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Posted 01 October 2011 - 14:45

It was the criminal bankers just like today.


That doesn't seem to add up.There was a plane already developed,tested and proven that could carry 55 passengers,weighed 40 tonnes total,using 4 Centaurus engines,at around 300 mph + and which was scrapped because the old allies of WW2 decided it presented a threat to their own aircraft manufacturing industries where the British already had the engine side of the deal.Bristol then went on to invest who knows how much,probably provided by the banks,in the abandoned Brabazon project,weighing 130 tonnes,carrying 100 passengers,at around 250 mph,using 8 Centaurus engines,which anyone could see wouldn't get off the ground literally or comercially.Meanwhile the Constellation went laughing all the way to the bank even with it's grenade US engines.

Just like the idea of building the Griffon Spit from day one and cancelling the Hurricane my logic says why didn't Bristol take on the Breda instead of going for the Brabazon and surely everyone at Bristol,including the firm's bankers,lost out as much, or more,than Breda did by cancelling the plane instead of just taking the drawings from the Italians and getting on with it. :drunk: :stoned:

Edited by Vanishing Point, 01 October 2011 - 14:50.


#122 WPT

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Posted 01 October 2011 - 17:11

Something that should be said and that I don't really understand: The American made plane flown by the pilot with the highest air kills was the P-39, and the pilot was Russian. Russia took all the P-39s they could get and the bulk of the P-63 production. Guess air combat on the Eastern Front was different. WPT

#123 Vanishing Point

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Posted 01 October 2011 - 19:08

Something that should be said and that I don't really understand: The American made plane flown by the pilot with the highest air kills was the P-39, and the pilot was Russian. Russia took all the P-39s they could get and the bulk of the P-63 production. Guess air combat on the Eastern Front was different. WPT


What was different about the Russian front was that Russia was able to sustain the type of losses that turned the whole idea of kill ratios and the idea of air superiority upside down.The Russian kill rate for the P39,or in fact any Russian operated aircraft,would have been irrelevant if it was applied to the Western front.That high rate of kills needs to be looked at in comparison to how many German and Russian operated aircraft were committed to the battles on the Eastern Front and the rate of losses actually sustained by the Russians to make those kills. :eek:

This JG fought in both theatres and their kill rate and ratios in Russia,versus that in the West,actually shows just how good the German aircraft were and therefore how good the aircraft used on the Western front,by the allies,actually needed to be.

Luckily the allied command didn't use the Russian statistics to cloud their judgement into thinking that aircraft like the P 39 would have won out in the western theatre.If the German v Russian kill rates and ratios were applied on the Western front the Germans probably would have won in the West easily and actually shows how good that,with the exception of the Hurricane, Merlin,Griffon and 2800 powered aircraft actually were.Especially when the performance of aircraft like the Corsair and the Bearcat in the Pacific theatre are included together with the T Bolt.

http://wikipedia.org...gdgeschwader_54

If you can find a copy of the book Alert in The West,by the Green Hearts pilot Willi Heilmann,it really says everything about what the Germans were up against with Griffon Spits,T Bolts and Mustangs versus Me 109's and FW190's during the later part of WW2.However it was the Griffon Spit that seems to have performed best and that was feared most of all.

Edited by Vanishing Point, 01 October 2011 - 22:46.


#124 Wuzak

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Posted 01 October 2011 - 23:39

Something that should be said and that I don't really understand: The American made plane flown by the pilot with the highest air kills was the P-39, and the pilot was Russian. Russia took all the P-39s they could get and the bulk of the P-63 production. Guess air combat on the Eastern Front was different. WPT



I believe that aerial combat on the Eastern Front generally took place at lower altitudes than on the Western Front. The P-39's lacking altitude performance wasn't such an issue, and the inclusion of a hub mounted cannon (37mm, though I believe many were refitted with 20mm Russian weapons) was appreciated.

#125 JtP1

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Posted 02 October 2011 - 18:59

A few points in the above thread.
A Sabre on its own cost more than a complete Spitfire. looking at the complexity of the sectioned one at Hendon, the cost is understandable. Iirc a sabre cost £15,000 in 44

There was never a shortage of fighters in the RAF in the BoB, there was a shortage of pilots. Fortunately there was an even bigger shortage of pilots in the Luftwaffe as any aircraft shot down fell mainly on British soil or the Channel. When the positions were reversed in 41 and the RAF carried daylight raids over France, the RAF lost more pilots than in the BoB.

The preference of radials over in inlines in commercial airliners is a maintainance thing. A defective cylinder can be changed in situ in a radial, the same with an inline, such as a Merlin involves an engine change or removal at the very least. When jet airliners came into service many airlines thought they would be uneconomic, that is until the own time was taken into consideration. an airliner flying the Atlantic with a combustion engine could expect to spend the folowing day having the engines serviced. The jet just turned round and flew back.

That leads to the question, what is the firing order for gas turbine engine?

#126 gruntguru

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Posted 02 October 2011 - 22:45

1

#127 Lee Nicolle

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Posted 03 October 2011 - 22:12

Sorry my bad, I was thinking of the work Barnes Wallis did at Vickers on the Lancaster and the armament developments for the aircraft.

Roy Chadwick deserves full credit for the Manchester design and the development of that underpowered aircraft into the Lancaster.

The Wellington was designed by Barnes and was the main bomber for the RAF right through the war.
It is a shame there are no flying ones left.

The Wellingtons may have been used right through the war but were hardly a mainbomber in the latter parts as they were out of date by then.

#128 mariner

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Posted 13 December 2011 - 22:34

My only excuse to resurrect this thread on aero engines is because today I read one of those " gosh - how amazing" bits

I have a book from the library I would highly recommend to any plane fan - " Big Wings" by Philp Kaplan ISBN 1 84415 187 6.

It is about the largest planes ever built over the years ,for the 1940's this was the B-36D US bomber with six piston engines and later four jet engines as well.

The " amazing" fact is that it carried five tons of engine oil for each full range mission , that equals one seventh of the actual bomb load.

Logically six 28 cylinder engines running for 18 hours on a 6,800mile mission will burn a lot of fuel but the idea of loading 11,000lbs of just engine oil into a plane is amazing.

I think it works out at 100lb per engine per hour ( roughly 14 gallons per hour?)

It makes you realize that a big side benefit of full jets ( like the B-52) was the reduced engine oil consumption which , at least partially, offset the terrible fuel burn of early jet engines.

Can you imagine using individual five litre containers to fill it up?

#129 GreenMachine

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Posted 14 December 2011 - 01:21

The " amazing" fact is that it carried five tons of engine oil for each full range mission , that equals one seventh of the actual bomb load. ... I think it works out at 100lb per engine per hour ( roughly 14 gallons per hour?)


:eek: :eek:

I know aero engine oil consumption is a fact of life that has to be accomodated, as it doesn't do to run out, especially over enemy territory :rolleyes: , but that figure I find astonishing, to the point of incredulity. I wonder what the Superfortress oil capacity is/was, as that would be the closest operational comparison to the B36.

I would also be interested to know what a Merlin consumption rate is, as another comparison, or the Griffins on the MR Shackletons. I presume that a liquid cooled engine would have tighter tolerances, and therefore lower oil consumption, but that would only affect oil consumption on start-up ... maybe?

Must spend more time googling methinks ...

On preview, 35 tons of bombs? I think not - 35,000 pounds perhaps. I wonder if the book author has got his units crossed ... for both bombs and oil.



#130 Wuzak

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Posted 14 December 2011 - 01:28

On preview, 35 tons of bombs? I think not - 35,000 pounds perhaps. I wonder if the book author has got his units crossed ... for both bombs and oil.



I think the B-36 could carry up to 80,000lb bombs.

#131 GreenMachine

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Posted 14 December 2011 - 05:08

I think the B-36 could carry up to 80,000lb bombs.



:blush: I think you are correct :blush:

Bllody hell! That thing is huge, especially for its time! 39 tons max bombload, or 4.5 tons over 6400kms, according to wikipedia. MTOW of 186 tons, payload 110 tons - no wonder they needed all those engines, and later versions could top 50,000ft.

Wikipedia says that each engine had a 100 gallon oil tank. On my maths that comes to about 2.7 tons assuming oil weighs about the same as water. As they could be aloft for 40 hours, that gives a consumption of around 2.5 gals/hour/engine, but the rate would presumably increase as range was traded for speed and the engines started working harder.

Actually, the consumption would be higher, as I am guessing they planned on landing with some oil left in the tank.

Thanks Mariner, I have leaned something today!


#132 cheapracer

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Posted 14 December 2011 - 06:52

That leads to the question, what is the firing order for gas turbine engine?


Just turn it over and follow the blades and see which get to top dead center in which sequence....


#133 Wuzak

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Posted 14 December 2011 - 08:00

:blush: I think you are correct :blush:

Bllody hell! That thing is huge, especially for its time! 39 tons max bombload, or 4.5 tons over 6400kms, according to wikipedia. MTOW of 186 tons, payload 110 tons - no wonder they needed all those engines, and later versions could top 50,000ft.

Wikipedia says that each engine had a 100 gallon oil tank. On my maths that comes to about 2.7 tons assuming oil weighs about the same as water. As they could be aloft for 40 hours, that gives a consumption of around 2.5 gals/hour/engine, but the rate would presumably increase as range was traded for speed and the engines started working harder.

Actually, the consumption would be higher, as I am guessing they planned on landing with some oil left in the tank.

Thanks Mariner, I have leaned something today!


IIRC the span of the tailplane was greater than the wingspan of a B-29.

originally the B-36 was intended to have 6 Lycoming XR-7755 liquid cooled radials (yes, that's 7755 cubic inches) rated at 5000hp, but had to settle for R-4360s rated at 3500-3800hp instead. The B-36 was chronically underpowered, so jet engines were added to give the beast some speed.

#134 Tony Matthews

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Posted 14 December 2011 - 10:19

One summer evening, many years ago, I was on the flying field of Letchworth Model Aero Club, a clear sky turning pink as the sun set, and everyone chatting before heading home, when a distant, low growl became apparent. Everyone looked around, up, then further up, until we saw it - a B36, very high up and crawling across the sky. Wonderful!

#135 mariner

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Posted 14 December 2011 - 11:53

The B-36 never fired a gun nor dropped a bomb in anger and was obsolecent whilst in production bcause the Boeing B-52 first flew in 1952. Nonetheless it apparently served one very valuable role for the USAF in that 25% of the 300 B-36's were kitted out as reconnaisance aircraft. Although they were slow they had very high ceiling for the day of 50,000 ft and very longe range so they were ideal for "spy" flights.

It is interesting that a piston engined plane could reach 50,000 ft. I guess the turbo-chargers worked pretty hard to get it up there.

#136 Wuzak

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Posted 14 December 2011 - 12:20

The B-36 never fired a gun nor dropped a bomb in anger and was obsolecent whilst in production bcause the Boeing B-52 first flew in 1952. Nonetheless it apparently served one very valuable role for the USAF in that 25% of the 300 B-36's were kitted out as reconnaisance aircraft. Although they were slow they had very high ceiling for the day of 50,000 ft and very longe range so they were ideal for "spy" flights.

It is interesting that a piston engined plane could reach 50,000 ft. I guess the turbo-chargers worked pretty hard to get it up there.


The Spitfire PR.XIX had a service ceiling of nearly 50,000ft and was recorded, on occasion (post war) above that altitude. No turbos for them.

Not sure what turbos the B-36 used. I think they may have been 2 CH turbos per engine - that is a C series (for use with 1800-2200hp engines) high altitude rated turbocharger. The critical altitude of the CH turbo was around 30,000-35,000ft IIRC. Up to that altitude the engine could maintain sea level power. Above that power fell away.

#137 Wuzak

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Posted 14 December 2011 - 12:29

The B-36 never fired a gun nor dropped a bomb in anger and was obsolecent whilst in production bcause the Boeing B-52 first flew in 1952. Nonetheless it apparently served one very valuable role for the USAF in that 25% of the 300 B-36's were kitted out as reconnaisance aircraft. Although they were slow they had very high ceiling for the day of 50,000 ft and very longe range so they were ideal for "spy" flights.


The B-36 program began early in the war, perhaps even before the US entered the war - around 1941, IIRC.

By the time it matured into a production ready aircraft the jet engine had demonstrated its advantages and was taking over, at least in military aircraft.

The B-47 would also have made the B-36 obsolete, flying before the B-52.

At least one B-36 was converted to become a YB-60. They removed the piston engines, cut the wings near the root and swept them back, adding an infill piece at the root. B-47/B-52 style podded jet engines were slung under the wing. But the performance wasn't up to that of the B-52, so it went no further.

Posted Image

Another proposal was to have large underslung turboprops.


#138 Kelpiecross

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Posted 14 December 2011 - 12:35

:eek: :eek:

I know aero engine oil consumption is a fact of life that has to be accomodated, as it doesn't do to run out, especially over enemy territory :rolleyes: , but that figure I find astonishing, to the point of incredulity. I wonder what the Superfortress oil capacity is/was, as that would be the closest operational comparison to the B36.

I would also be interested to know what a Merlin consumption rate is, as another comparison, or the Griffins on the MR Shackletons. I presume that a liquid cooled engine would have tighter tolerances, and therefore lower oil consumption, but that would only affect oil consumption on start-up ... maybe?

Must spend more time googling methinks ...

On preview, 35 tons of bombs? I think not - 35,000 pounds perhaps. I wonder if the book author has got his units crossed ... for both bombs and oil.


The Merlin was pretty fierce on oil consumption - up to a couple of gallons per hour. I think even small aero engines like the DH Gypsies used a lot of oil.

To put B36 etc. weights etc. into a modern perspective:
http://en.wikipedia...._Takeoff_Weight
I think the maximum take off load is usually about half the MTOW.

And they still seem to climb away from takeoff at a 45 degree angle - shows what a couple of hundred thousand horsepower can do.



#139 Magoo

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Posted 14 December 2011 - 14:53

I'm not sure the true operating ceiling of the Convair B-36 was ever disclosed. High enough.

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#140 Bob Riebe

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Posted 14 December 2011 - 20:24

Like Wuzak said, the R-4360 used in the FG-2 (a F4U built by Goodyear) was developed for low altitude intercept of Kamikaze. Top speed at altitude not as high as the ~445MPH of the F4U-4. Prodution of the R-4360 by the end of the war totaled ~135 units. Only ~20 FG-2s were built. The XP-47-J managed 505MPH. A P-51G (only two built) managed 495MPH and the P-51H (555 built, but too late for the war) managed 483MPH.
Have read RR had on the test bed during the war a Merlin on 150 fuel, 100"Hg, and ADI that produced 2640HP (maybe the 17.5SM?). What does anyone know about this? WPT

The XP-47J used the 2800; the XP-72 used the 4360 and attained ( I believe) 480 some mph.

The P-47J was killed due to acceptance of the XP-72 which never went into production.

--------------------------I screwed up corrected------------------

Edited by Bob Riebe, 15 December 2011 - 03:33.


#141 Bob Riebe

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Posted 14 December 2011 - 20:30

I think the B-36 could carry up to 80,000lb bombs.

Internally it could carry two 42,000 lb bombs designed just for it.
Short range load I read years ago was 85,000 lbs. of bombs.

The B-60 could carry a similar load internally.
Those forty thousand plus bombs would have made quite the impression in Vietnam. (or Afghanistan)


#142 Wuzak

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Posted 14 December 2011 - 20:38

The XP-47H used the 2800; the XP-72 used the 4360 and attained ( I believe) 480 some mph.

The P-47H was killed due to acceptance of the XP-72 which never went into production.



The XP-47H used the experimental Chrysler IV-2220 - an inverted V-16 using 16 separate liquid cooled cylinders based on the "hyper" cylinder design evolved by the USAAC's engineering division at Wright Field. This meant 2 valves per cylinder in a hemispherical combustion chamber.

Power was taken from the centre of the crankshaft to drive the prop and accesories.

It was very similar in capaciy to the Griffon (2240ci) but weighed 400lb+ more and was 40" longer than the 2 stage Griffon.

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#143 Wuzak

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Posted 14 December 2011 - 22:11

XP-47H

Posted Image

Edited by Wuzak, 14 December 2011 - 22:12.


#144 GreenMachine

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Posted 14 December 2011 - 22:55

Internally it could carry two 42,000 lb bombs designed just for it.
...
Those forty thousand plus bombs would have made quite the impression in Vietnam. (or Afghanistan)


Sure would - they were the 1st gen nukes ... :eek:

I understood that they could only carry one, as it required the merging of two of the three bomb bays - I take that as implying the capacity 'cubed out' as the truckies say. In any event, due to the slow speed of the aircraft, survival from a single nuke blast was problematic at best, I wouldn't want to try a second if I managed to escape the first, might be seen as tempting fate ...



#145 Lee Nicolle

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Posted 14 December 2011 - 23:08

:blush: I think you are correct :blush:

Bllody hell! That thing is huge, especially for its time! 39 tons max bombload, or 4.5 tons over 6400kms, according to wikipedia. MTOW of 186 tons, payload 110 tons - no wonder they needed all those engines, and later versions could top 50,000ft.

Wikipedia says that each engine had a 100 gallon oil tank. On my maths that comes to about 2.7 tons assuming oil weighs about the same as water. As they could be aloft for 40 hours, that gives a consumption of around 2.5 gals/hour/engine, but the rate would presumably increase as range was traded for speed and the engines started working harder.

Actually, the consumption would be higher, as I am guessing they planned on landing with some oil left in the tank.

Thanks Mariner, I have leaned something today!

The Lancs carried 22400 aprox lbs[10 ton] during the war. Bomb bay doors were a thing of the past!
I feel those numbers for oil tanks may be skewed too, and they would not have used that much oil anyway. It would have been a thick cloud of blue smoke all the way to use 2 and a half gallons an hour. 2 1/2 gallons per mission for 4 engines would be closer to the mark. Maybe they used one oil tank for the 4 engines. Though that would never be very clever as one stray bullet would bring the plane down wheras an individual engine with a 10 gallon oil tank would be closer to the mark. And those tanks would probably be well protacted and self sealing [to a degree] anyway.

#146 Wuzak

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Posted 14 December 2011 - 23:27

Sure would - they were the 1st gen nukes ... :eek:


No, they weren't.

They were a larger development of Barnes Wallis' Tallboy and Grand Slam. It was a deep penetration bomb designed to destroy hardened bunkers and the like.

T-12 Cloudmaker

Note that the B-36 bomb bay was designed around this bomb.


I understood that they could only carry one, as it required the merging of two of the three bomb bays - I take that as implying the capacity 'cubed out' as the truckies say. In any event, due to the slow speed of the aircraft, survival from a single nuke blast was problematic at best, I wouldn't want to try a second if I managed to escape the first, might be seen as tempting fate ...


The B-29s Enola Gay and Bockscar were modified to carry Little Boy and Fat Man because neither of these bombs would fit in the standard bomb bay. The B-29s modified to carry nuclear bombs were called Silver Plate.

Little Boy and Fat Man were both around 10,000lbs. Physically Little Boy could have fitted inside the bulged bom bay of the Mosquito B.XVI, but getting off the ground may have been a different matter.

The B-29 used a similar bomb bay and bomb rack to teh B-17 - which limited the size of bombs that could be carried. The nominal max bomb load for the B-29 was 20,000lbs, more than enough to carry the A-bombs, but needing modifications to allow the bomb to fit. B-29s were also modified to carry the Grand Slam (22,000lbs), with the bomb half proturuding beneath the fuselage, and were also fitted with a pair of Tallboys (12,000lb each) on under wing pylons.

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#147 Wuzak

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Posted 14 December 2011 - 23:27

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#148 GreenMachine

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Posted 15 December 2011 - 01:13

Thanks Wuzak, I missed that bit :rolleyes: . I should also clarify that these were 1st gen H-bombs, not A-bombs.

Both T12 and Mk 17 were similar weight and dimensions, and I haven't been able to find any dimensions for the bomb bays to see how they could accomodate two internally. Seems like they had the lifting capacity for two anyway. Bob, can you elaborate any further regarding the customisation of the design around the bombs?

Given the difference between max bombload and bombload at max range, I wonder what the range (or operational radius) would have been with one, or two, of these. Beyond the wiki article, seems like most of the detail is in books, or at least I have not found it on the web.

I must say that the investment in resources for its original purpose is rather staggering, and could only have been considered by America (realistically). Apparently predicated on Britain losing out to Germany, they would build this aircraft as a trans-oceanic bomber, to deliver 4.5 tons of bombs to Germany. If that strategic scenario had come to pass, they would have needed a lot of them, over a long period, to seriously weaken Germany.

My curiousity about this aircraft has been seriously piqued, and I feel an overpowering urge to visit a couple of the local secondhand bookshops ... :) .

#149 bigleagueslider

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Posted 15 December 2011 - 02:06

More impressive than the B-36's engine oil consumption rate or bomb load was the size of the tire on the original single wheel MLG. :eek:

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#150 Wuzak

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Posted 15 December 2011 - 02:18

Here's one that I have (but not readily to hand)

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As for customising the bomb bay, it is simply arranging the doors, attachment points, bulkheads and whatever to fit the required bomb.

The Lancaster's bomb bay was the result of an official requirement to carry a very large torpedo, and not bombs. Thus it was a long uninterupted bomb bay, which could take quite large bombs (Tallboy fitted, but needed slightly bulged doors, Grand Slam could only be fitted with doors removed).

Lancaster Bomb Load Configurations

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Compare that to the B-17

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The B-17 bay didn't allow for long bombs - the largest bomb that could be carried internally was a 2000lb GP bomb, and then only two of them at a time. The B-29 had a similar bomb bay arrangement, only it had 3 of them.

Here's a pic of the B-36 bay (part thereof)

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If you are ever in Ohio, check out the USAF museum at Dayton. They have a B-36 in their hangar including an original single wheel main landing gear assembly (changed it to multiple wheel bogies later).

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