The lack of a four engined bomber

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Topspeed
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Post by Topspeed » 05 Aug 2004 22:28

GP,

Interesting I never tought or knew that. So alied were really far more advanced than the germans..did the 87 octane fuel have something to do with this ?

JT

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Post by Witch-King of Angmar » 05 Aug 2004 22:31

gabriel pagliarani wrote:The Alieds used a simple electronic device used as wave-form detector of HV sparks (hoscillograph ?= oscillografo in italian..sorry but I have not found the corresponding british term) by mean of that the engineer on board was able to look for the closest at the "drew point" of the air-gasoline mixture in the way to reach the best stechiometric values before sparking against pistons and making an hole in those.(This phoenomenon is well known by everybody as "head-beating" in the cruise roar of any Otto-engine.) The lack of electronic cathodic tubes in the whole Reich never allowed a so intensive use of those "wave-form detectors" (...one each engine!) as Allieds did. Axis were obliged to build only 2 or 3 engines powered planes because they never managed the " full stechiometric live control" of fuel consumption as Allieds did during WW2.
Germans had a similar device under development for large overseas aircraft, which allowed the flight engineer to overlook the engine data(mixture, spark timing, rpm etc) and run all engines from a central station - for them it was to be easier to implement the device, since most German aircraft flew on fuel-injected engines, not carburettor. (Nowadays all fuel injection engines do this stoichiometric live control). Me-264 (which flew during the war as a prototype) could fly in theory over 6,000km.

~The Witch-King of Angmar

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Post by gabriel pagliarani » 06 Aug 2004 21:34

Witch-King of Angmar wrote:...Germans had a similar device under development for large overseas aircraft...
Exactly, Witch. The same German device was commonly employed in Italy too by Regia Aeronautica. The only problem was in the fact that there was one of those devices each ground handling unit! At least an instrument any 24 planes plus T-planes. American flight engineers had to watch 4 of them continuosly on EACH Fortress. Ratio = 1 german device Vs. 98 allied devices. The born of popular TV in USA during '40s had something to share with this wide quantity of small cathodic tubes produced at low prices...Any way the stechiometric live control had to be performed both on injection fuel systems and /or carburetors. The only difference is in the fact that actual microprocessors do the same job made by the American flight engineers billions of times per second without any error. Any cheapest korean car has a small electronic american flight engineer in it. This is a real progress. About Octane number it has great importance about the quality of the steels used on the engines, but the calorific power is about the same of 140 N.O.R.M. used by Allieds and the energy lost during the ride is directly proportional to the calorific power of the fuel. Calorific power = (joules* mol) in SI or (joules * gram) in CGS). At the contrary I think that 140 NORM fuel had a smaller calorific power than 87 NORM because mixed with methanol and alcoholes have less calorific power than
gasoline. But I am not totally sure of the mix. Therefore the best savings in range were performed only by the live stechiometric control exerted by flight engineers during long range raids.

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Post by Witch-King of Angmar » 07 Aug 2004 00:38

gabriel pagliarani wrote:The born of popular TV in USA during '40s had something to share with this wide quantity of small cathodic tubes produced at low prices...
Germans did also mass-produce TV sets with their respective CRTs since 1936, this was less of an issue for them compared to Italy.
gabriel pagliarani wrote:Any way the stechiometric live control had to be performed both on injection fuel systems and /or carburetors. The only difference is in the fact that actual microprocessors do the same job made by the American flight engineers billions of times per second without any error. Any cheapest korean car has a small electronic american flight engineer in it. This is a real progress.
It's near the border of impossibility to perform mixture control on carburettors, that is any producer back in the 1980s dropped the idea and concentrated on the fuel injector/electronic distributorless ignition couple. And also mechanical injection systems had all the time been a pain in the ass, since Daimler-Benz employed them on airplanes and later(1950s) on cars.
gabriel pagliarani wrote:About Octane number it has great importance about the quality of the steels used on the engines, but the calorific power is about the same of 140 N.O.R.M. used by Allieds and the energy lost during the ride is directly proportional to the calorific power of the fuel. Calorific power = (joules* mol) in SI or (joules * gram) in CGS). At the contrary I think that 140 NORM fuel had a smaller calorific power than 87 NORM because mixed with methanol and alcoholes have less calorific power than
gasoline. But I am not totally sure of the mix. Therefore the best savings in range were performed only by the live stechiometric control exerted by flight engineers during long range raids.
Octane number is not a measure of fuel quality or BTUs/lbs, it's a measure of the ability to resist detonations/knocks. That is, 87 octane = 87% of the resistance of pure octane. Once the engineers had higher-octane gas on hand, they could design an engine with higher compression ratios and advanced ignition timing, yet higher octane on an engine designed to run on lower brings no advantage. (Try to run a car designed for 91 octane gas on 95, 98, 100 and 106 octane, it runs just the same) Germans had two types of aviation gasoline, type B(87 octane) and type C(100 octane), and aircraft engines were designed for them. Rolls-Royce Merlin & Griffon engines needed 153 octane avgas, for the record.

~The Witch-King of Angmar

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Post by Huck » 07 Aug 2004 02:24

Lkefct wrote:None of those planes is avalible for the BoB. The comparision being made is the 2 engined bombers of the day vs 4 engne planes from late in the war. How can that be an accurate assesment of the improvement of the planes? Of course a 4 engine late war plane is going to have better performance towards winning the BoB. That is like saying that the USAAF would perform better in the late with smart bombs. You are applying the wrong era of technology.

The issue is not do 4 engine bombers perform better, that is obvious. The question is would it have beneftied germany in WW2. Agin, the only targets that they could not hit because of a lack of range are

1). Soviet factories
2). US anything
3). NAval recon.

[...]

Building 4 engine bombers make little or no sense to the german military. It just does not add that much to what they are doing, if you examine what they are doing critically. For the Allies, they are an indespencable part of the war effort. By the situations faced by the 2 sides is not reversible. What do you need a heavy bomber for that the medium bombers the germans did use can't do? My answer is that the only thing they cannot do that makes any sense is naval recon.

I'm sorry, I was just making a general observation, it was not an direct answer to your post. I do agree with your points. Germany did not really need a 4 engine bomber, unless there was a serious plan for an antishipping campaign.

Indeed a commited antishipping campaign could inflict disastrous losses to convoys operating in Atlantic, also to warships. It is not well known, but LW destroyed more British medium size warships (light cruisers, destroyers) than Kriegsmarine, and all this in absence of an official LW campaign against RN.

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Post by Huck » 07 Aug 2004 02:32

Lkefct wrote: The HE 177 was a poor design in that they could not find a way to cool the engines adequately. Putting 2 engines on the same shaft reduces drag, but was too difficult to keep cool, and the engines where always bursting into flames. There was also a lot of very complex engineering on the gears that onnected the engines to the shaft, and it was never a reliable aircraft. My understanding is that they where also used mainly as bombers, and not in the role that might have been the most fruitful.


700+ He-177 new airframes (this total does not take into consideration refits to later versions) saw active service with LW, for a total period slightly larger than 2 years. Until autumn of '43 He-177 was in operational tests (it flew combat missions for tests on plane and tactics). The first groups to adopt He-177 were I./KG50 and I./KG40 in mid '42, I./KG50 being the first group to reach operational status. Most of the other groups that used He-177 became fully equipped sometime in late '43 - early '44. Engine problems were rectified by a team specially designated at the beginning of '43. DB-610 equipped He-177 ran as reliable as any other LW bomber provided adequate maintenance and operation.

During this period ~140 He-177 were lost due to enemy action (40 unserviceable He-177 were captured and/or destroyed in June '44 in France) and ~130 He-177 were lost in various accidents. This is actually a good loss rate for a ww2 bomber. You can compare it with B-29 loss rate, B-29 and He-177 sharing many elements (from design complexity and engine problems to comparable capabilities, operations and loss rate): in slightly more than 1 year of service B-29 groups lost 500 planes from the 1500 delivered. From the 500 lost only 128 were lost due to enemy action, the rest of them being accidents, mostly engine related.

Lkefct wrote: In any case, there were never that many He 177 or FW 200 Conders produced, not enough to have a large role in WW2. Neither was avalible in sevice during the BoB, which is when I thought most people where assuming it was to be used. The Ural Bomber idea is just nuts since target identification, and navigation through Central russia would be almost impossible. If you don't use a 4 engine plane for that, the only other role that makes sense is the naval recon idea. Otherwise, you can use a 2 engine bomber to reach the tactical targets that are left, and you don't need a 4 engined plane to do that.
Fw200 could never be an effective bomber. He-177 was another matter. The only problems He-177 had were behind closed doors at RLM.

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Post by Huck » 07 Aug 2004 02:47

gabriel pagliarani wrote:Effectively there was a wide technological gap in 4 engined planes among Axis and Allies: evidently the Allied " know how" in this field was the leader one. ...
Quite the opposite is true, German engines had the best SFC, I have the original ww2 engine charts for all major ww2 engines. R-2000 (C54 engine - DC6, DC7 are postwar developments) was a simple enlargement of R-1830, I really doubt there is something to mention about this engine (the only thing I found is that it had a 2 position manually selected spark advance, however dropped with later variants). If you want to prove that this most of the time overlooked engine was a technological marvel, please post its SEFC chart (specific engine flight chart) and we'll compare it with German engines.

BTW He-177 had similar payload/range capabilities with B-29, though it was roughly two times smaller. Could it be because He-177 had more efficient engines (and a more efficient design overall)?

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Post by Huck » 07 Aug 2004 02:53

Witch-King of Angmar wrote:
gabriel pagliarani wrote:The born of popular TV in USA during '40s had something to share with this wide quantity of small cathodic tubes produced at low prices...
Germans did also mass-produce TV sets with their respective CRTs since 1936, this was less of an issue for them compared to Italy.
gabriel pagliarani wrote:Any way the stechiometric live control had to be performed both on injection fuel systems and /or carburetors. The only difference is in the fact that actual microprocessors do the same job made by the American flight engineers billions of times per second without any error. Any cheapest korean car has a small electronic american flight engineer in it. This is a real progress.
It's near the border of impossibility to perform mixture control on carburettors, that is any producer back in the 1980s dropped the idea and concentrated on the fuel injector/electronic distributorless ignition couple. And also mechanical injection systems had all the time been a pain in the ass, since Daimler-Benz employed them on airplanes and later(1950s) on cars.
gabriel pagliarani wrote:About Octane number it has great importance about the quality of the steels used on the engines, but the calorific power is about the same of 140 N.O.R.M. used by Allieds and the energy lost during the ride is directly proportional to the calorific power of the fuel. Calorific power = (joules* mol) in SI or (joules * gram) in CGS). At the contrary I think that 140 NORM fuel had a smaller calorific power than 87 NORM because mixed with methanol and alcoholes have less calorific power than
gasoline. But I am not totally sure of the mix. Therefore the best savings in range were performed only by the live stechiometric control exerted by flight engineers during long range raids.
Octane number is not a measure of fuel quality or BTUs/lbs, it's a measure of the ability to resist detonations/knocks. That is, 87 octane = 87% of the resistance of pure octane. Once the engineers had higher-octane gas on hand, they could design an engine with higher compression ratios and advanced ignition timing, yet higher octane on an engine designed to run on lower brings no advantage. (Try to run a car designed for 91 octane gas on 95, 98, 100 and 106 octane, it runs just the same) Germans had two types of aviation gasoline, type B(87 octane) and type C(100 octane), and aircraft engines were designed for them. Rolls-Royce Merlin & Griffon engines needed 153 octane avgas, for the record.

~The Witch-King of Angmar

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Very good points, Witch-King of Angmar.
One mention: Allies used for late war planes 100/130 fuel. The 150 octane was used solely by the British planes exclusively for low level interception (mostly V-1s). Americans had a similar fuel, 115/145 grade fuel, but it was used only in Pacific in '45.

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Post by gabriel pagliarani » 08 Aug 2004 00:44

Witch-King of Angmar wrote:... It's near the border of impossibility to perform mixture control on carburettors, that is any producer back in the 1980s dropped the idea and concentrated on the fuel injector/electronic distributorless ignition couple. And also mechanical injection systems had all the time been a pain in the ass, since Daimler-Benz employed them on airplanes and later(1950s) on cars.....

[Witch-King :D
Engines on airplanes, expecially bombers or cargos, work at steady cruise regime (fixed nos. of revolutions of the crankshaft per second).
At the contrary of your own statement it's easy to trim the quantity of moles of gasoline spraied into air even if the engine is fed thru a carburettor . The right mix gasoline! air might be between those 2 extreme ratios 1/14 (rich or fat) and 1/24 (poor or slim) . The difference is enormous because the fuel consumption is little less than doubled when the mix is rich!Cars are not planes and there is no fixed cruise regime. However Mitsubishi just sold a beatiful car with a carburettor trimmed by a computer. The same device was fitted on some Yamaha and Honda bikes and both Mikuni and Keihin carburettor producers have those models on list price till 1985. consequently you are right if you say tha on cars it is very difficult. "Impossible" is a word beloved by weak people only. :idea: About NORM nobody said there is a link between octane and fuel quantity or BTU (...why this fool thermal unit , Witch? It is just used only in air conditioning: have you some interest in air cooling? 8) Pls use SI or CGS units) But there is a link between gasoline chemical composition and the energy fred when burned.
But the job of the wave detector was not in in looking for the slimmest mix was possible but in adjusing the leading time gap between spark and detonation. The slimmest mix was trimmed at ground by handling during tune up procedures: Allied ground engineers were fred to look for the best "poor" mix useful for extreme long ranges while on Axis planes their opponents were obliged to look for an half-tuning.
I never supposed thaT in 1937 in Germany there was a TV in any family as in USA in 1948. Please revise this wrong statement.


EMPEROR GP 1° :lol: :lol: :lol:

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Post by Witch-King of Angmar » 08 Aug 2004 13:51

gabriel pagliarani wrote:BTU (...why this fool thermal unit , Witch? It is just used only in air conditioning: have you some interest in air cooling? 8) Pls use SI or CGS units)
Could it be because our American friends seem helpless when someone talks about calories per kg? ;)
gabriel pagliarani wrote:I never supposed thaT in 1937 in Germany there was a TV in any family as in USA in 1948. Please revise this wrong statement.
Neither was in USA in 1937....

~The Witch-King of Angmar

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Post by gabriel pagliarani » 08 Aug 2004 15:21

Witch-King of Angmar wrote:....Could it be because our American friends seem helpless when someone talks about calories per kg? ;)....Neither was in USA in 1937....
British Termal Unit (BTU) is not american but British only.This kind of unit of measure is wordwide used in air-conditioning only, and planes are not coolers even if they have more than a fan. :lol: About cathodic tubes in 1940 any 4 engined allied bomber had 4 of them fitted in the flight engineer's panel, in the while Germans had not the 4 engined bomber nor the panel nor the 4 cathodic tubes to fit into a never built cockpit. That's enough? :roll:

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Post by Hop » 08 Aug 2004 15:43

One mention: Allies used for late war planes 100/130 fuel. The 150 octane was used solely by the British planes exclusively for low level interception (mostly V-1s).
This is often written in books etc, but it's not actually true.

100/130 octane fuel remained more widespread than 100/150, but 100/150 was used for a lot more than just chasing V-1s.

The British began trials of 100/150 in 1943, and began converting all the Spitfire IX squadrons in Britain in the spring of 1944. In early summer 1944, all US 8th AF fighter units switched to 100/150, and remained on it until March or April 45.

RAF fighter command, which was renamed Air Defence Great Britain, used 100/150 in almost all it's fighters from the summer of 44 until the end of the war. 2nd Tactical Air Force, the British AF based on the continent after the Normandy landings, switched to 100/150 in January 1945.

In July 1944, the RAF used 12,000 tons of 100/150, the USAAF 20,000 tons, by Jan 45 the figures were USAAF 20,000 tons, ADGB 10,000 tons, 2nd TAF 15,000 tons.

As a guide to how much fuel that actually is, Fighter Command used 22,000 tons during the 4 months of the Battle of Britain.

British production figures for 100/150 and 100/130 octane, in US barrels:

Code: Select all

Date          100/150    100/130
March 44    221400     138400 
April 44      315400     137700
May 44        43800      471000
June 44       71400      340700
July 44       217300     118100
August 44   344800     136000
Sept 44      278900     143200
Oct 44        316800     159200
Nov 44       214700     211100
Jan 45        294800     184900
Feb 45        284300      84300
March 45    298000     127200
April 45      209500     219300
As you can see, 100/150 production overtook 100/130 production from summer 1944 onwards.

All this info has been uncovered from the British national archives over the last couple of years by Neil Sterling, and the original docs have been posted on a couple of aviation related boards. Some of the stuff, but more how it realtes to performance than production, can be found at http://www.fourthfightergroup.com/eagles/spit9.html

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Post by gabriel pagliarani » 10 Aug 2004 00:10

Not a barrel of 87 NORM fuel in the whole Allied assett! The imprecision among 100/150 NORM was probably due to an intensive use of additives. I don't think it was possible to reach 150 NORM by adding lead tetrahetyle only and the refinetion process by cracking tecnology never permitted the mass production of aromatics like benzene. Too much lead caused the formation of a lead bridge shortcircuiting the electrodes of spark plugs during long cruises, and actual aromatics distilled by reforming technology (benzene) were not intensively produced yet: consequently I think the Octane additive had to be alcoholic . A lot of methanol for Fortresses and their escorts had to be added to the barrels listed by Hop just before any mission. At least 5-10% to be added to the total reported. About the differences between ETO and PTO gas quality thre was no technical reason: simply gasoline for USAAFs was distilled directly in England. Logistic considerations, not technicals. Surely the same gasoline was distributed among allied sqdns in England and additives made the differences reported.

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Post by gabriel pagliarani » 10 Aug 2004 00:50

Huck wrote:...Quite the opposite is true, German engines had the best SFC, I have the original ww2 engine charts for all major ww2 engines. R-2000 (C54 engine - DC6, DC7 are postwar developments) was a simple enlargement of R-1830, I really doubt there is something to mention about this engine (the only thing I found is that it had a 2 position manually selected spark advance, however dropped with later variants). If you want to prove that this most of the time overlooked engine was a technological marvel, please post its SEFC chart (specific engine flight chart) and we'll compare it with German engines...
I will show you a booklet my dad left among his own flight manuals. It was related to the procedures to tun up the engines of DC-7. And I am not sure that DC-7C was equipped with radials...Gimme me the time to find it...your SEFC has nothing to share with this tune-up procedure. R1830 "overlooked" in comparison with Piaggio engines? :lol: :lol: :lol: "Overlooked US radials" Vs. "Superseeded Italians" 4:0
About He-177 any comparison with allied 4 engines is specious. You said tha it was a 4 engine bomber because it had a twin tandem linear 12 cylinders engine per nacelle. but R1830 engine was a tandem radial 9x2 engine consequently B29 was a 4 nacelles-8 engine bomber.... no comparison hence allowed. :P About the performances you pretend I am convinced that He-177 was the biggest flop in the long story of LW. Without defensive 360° heavy gunned turneable turrets and 2 nacelles offering an only target for any couple of engines, He 177 was disposed on Eastern front only because western fighters had to reduce it in hamburgers too easily. B29 was a masterwork in comparison with He 177, papers or not.

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Post by Witch-King of Angmar » 10 Aug 2004 11:59

gabriel pagliarani wrote:About He-177 any comparison with allied 4 engines is specious. You said tha it was a 4 engine bomber because it had a twin tandem linear 12 cylinders engine per nacelle. but R1830 engine was a tandem radial 9x2 engine consequently B29 was a 4 nacelles-8 engine bomber.... no comparison hence allowed. :P
He-177 had 4 engines, each DB-610 powerplant was made up by two DB-605 engines united by a gearbox, but each of the DB-605 engines had it's own fuel feed, ignition and controls. Mounting each DB-605 engine separately with it's own propeller would bring no advantage, only increase drag.

On the other side, it had, like most German bombers, a low ceiling (about 8000m full loaded). The Allied were interested to develop high-altitude bombers before 1939, for they expected a fierce AA defense from the potential enemy which Germany was, and hoped they could overcome it by climbing up; Germans did not have to deal with this problem.

~The Witch-King of Angmar

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