Arado 234 bombing raid on Philips factory

[Von Schadewald]

In 1944/45 Arado 234 jets bombed the Philips factory in Holland. Are there any details how succesful was this raid and from what height? How accurate was the single-seat Arado as a bomber?

[Karl234]

This model ever fly???

[Soylent_Dan]

Sorry no answer from me but if anyone is near Washington D.C. you can see this plane in the new Air & Space museum out near Dulles...a nice restoration job!

[Paul Lakowski]

If a bomber is said to have a range of 1000 miles with 2000 lb bombload @ 500 mph, does that mean it can fly 1000mile drop the bombs and go home or does it mean that it has an endurance of only 2 hours no matter where it goes with that bomb load?

[Xavier]

the plane was first and mostly used in high altitude recon missions over Englad, yes, it flew..

Then Hitler decided he wanted a bomber, (if I recall correctly, it was nicknamed "blitzbomber or something like that) and all advantages in speed and endurance were lost to the bombload

another case of too litle, too few..
best regards

Xavier
Instandsetzungtruppfuhrer

[Paul Lakowski]

Those engines on the AR-234 look alot bigger than the Me-262 engines, how heavy were they?

[Huck]

Those engines on the AR-234 look alot bigger than the Me-262 engines, how heavy were they?

Both planes used Jumo 004, which had around 750 kg (I have exact weights at home if you are interested).
Truth is Me-262 was not really a small plane and Ar-234 was not very big.
Me-262 was twin engine fighter, Ar-234 a light bomber, those 2 classes often overlap.

[Paul Lakowski]

Those engines on the AR-234 look alot bigger than the Me-262 engines, how heavy were they?

Both planes used Jumo 004, which had around 750 kg (I have exact weights at home if you are interested).
Truth is Me-262 was not really a small plane and Ar-234 was not very big.
Me-262 was twin engine fighter, Ar-234 a light bomber, those 2 classes often overlap.

Thanks Huck, I guess thats the Artists perogative to exagerate for image effects!

Hey were here speaking of Jumo jet engines with Huck, so were Hop?Just kidding I appreciate the effort that both of you put into this and wouldn't trade it for the world.

The Ar-234C would have had two Jumo-004B per wing and that would have increased speed altitude and range payload.

Any way found this info online at http://www.freeglossary.com/Jumo_004


Interesting stuff! It speaks of C and D models that were ready for producion when the war ended [ ~ year after mass production began]. They feature a 10% increase in thrust in the C model and ~ 17% increase in thrust in the D model. Any clues as to how much this would increase velocity and altitude?



Next it speaks of the D & E model having a fuel flow regulator to eliminate the notorious 'fuel dumping' problem. That got me to wondering how much of a difference such a device could have made [if it worked as advertised]. I read that Jumo-004B was bench tested to 100 hours with out failure and I was wondering if the fuel dumping problem was the prime reason for why operational engines got so low life [10-25 hours] BTW the author notes that in the hands of veterans, engine life doubled.

I wonder if the plans were for these to be mounted on future production Me-262/Ar-234?

Finally The Jumo 004H looks to be an interesting future replacement for double mounted Ar-234C models offering same thrust for 1/2 the number of engines and saving 1000kg as well!

Any one got a clue how much more fuel efficent and reliable these "turboprop engines" are and is there any way of figuring out how "4600 ehp" compares to jet engine thrust?



BMW 003 turbo jet Specifications
Length: 3.53m (11' 7")
Diameter: .69m (27")
Weight: 562 kg (1 250 lb)
Thrust: 7.8 kN (1 778 lb)
Maximum RPM: 9 500
Fuel consumption: 1.31 kg/(km/h)

Jumo-004B Turbojet Specifications [8 Axial flow stages 6 individual combustion 1 turbine stages ]
Length: 3.86 m (12 ft 8 in)
Diameter: 810 mm (32 in)
Weight: 719 kg (1 585 lb)
Thrust: 8.8 kN (1 980 lb)
Maximum rpm: 8 700
Fuel consumption: 1.42 kg/km/h

[Theo]1944 Jumo-004C Turbojet Specs [8 Axial flow stages 6 individual combustion 1 turbine stages ]
Length: 3.86 m (12 ft 8 in)
Diameter: 810 mm (32 in)
Weight: 720 kg (1 585 lb)
Thrust: 1015kg (2240 lb)
Maximum rpm: 8 700
Fuel consumption: 1.39 kg/km/h

[Pro] 1945 Jumo-004D /E Turbojet Specs [8 Axial flow stages 6 individual combustion 1 turbine stages ]
Length: 3.86 m (12 ft 8 in)
Diameter: 810 mm (32 in)
Weight: 720 kg (1 585 lb)
Thrust: 1015kg (2315 lb)
Maximum rpm: 10,000
Fuel consumption: est 1.33 kg/km/h ? [life 150 hours due to fuel dump control?]

[Pro] 1946 Jumo-004H Turbojet Specs [11 Axial flow stages 8individual combustion 2turbine stages ]
Length: ?
Diameter: ?
Weight: 1200 kg (2646 lb)
Thrust: 1800kg (3970 lb)
Maximum rpm: 6,600
Fuel consumption: 1.2 kg/km/h ?

[Pro] 1946 Jumo-012 Turbojet Specs [11 Axial flow stages 8individual combustion 2turbine stages ]
Length: ?
Diameter: ?
Weight: 2000 kg (4410 lb)
Thrust: 2780kg (6130 lb)
Maximum rpm: 5,300
Fuel consumption: 1.2 kg/km/h?

[Pro] 1946 Jumo-012 Turbojet Specs [11 Axial flow stages 8individual combustion 2turbine stages ]
Length: ?
Diameter: ?
Weight: 2600 kg (5733 lb)
Thrust: 4600 ehp
Maximum rpm: 5,000


http://www.freeglossary.com/Jumo_004

[Huck]

If a bomber is said to have a range of 1000 miles with 2000 lb bombload @ 500 mph, does that mean it can fly 1000mile drop the bombs and go home or does it mean that it has an endurance of only 2 hours no matter where it goes with that bomb load?

A serious source always gives the range of a bomber together with bombload, speed and altitude. All those factors affect the range a lot.
For example climbing to cruise altitude for a full loaded ww2 bomber could take an hour and a lot of fuel.
Recalculating the range of a bomber after fuel tanks were hit was a maximum responsability task for the navigators and they had a lot of parameters to take into account.

[Huck]

Thanks Huck, I guess thats the Artists perogative to exagerate for image effects!

Hey were here speaking of Jumo jet engines with Huck, so were Hop?Just kidding I appreciate the effort that both of you put into this and wouldn't trade it for the world.

I'm happy that you found our efforts worthwhile, but we really do not deserve the credit. We are aviation enthusiasts, just like you.

The Ar-234C would have had two Jumo-004B per wing and that would have increased speed altitude and range payload.

Ar-234C was powered by 4 BMW 003 (not Jumo 004). I cannot say anything about the credibility of the performance numbers listed for both Ar-234B and C since I never saw Rechlin tests for either one, and available sources are often in disagreement. In contrast, Me-262 performance numbers are trustworthy.

Any way found this info online at http://www.freeglossary.com/Jumo_004

Interesting stuff! It speaks of C and D models that were ready for producion when the war ended [ ~ year after mass production began]. They feature a 10% increase in thrust in the C model and ~ 17% increase in thrust in the D model. Any clues as to how much this would increase velocity and altitude?

Jumo 004 D designation if for Jumo 004B-3 (or B-4 in British sources, I personally prefer the designation found in Soviet and French sources in this matter, because they did use the engine in their own applications - immediatelly after the war the was a hunt organized for those particular engines) without the RPM limitation, which brought a thrust increase, but engine life remained comparable with that of Jumo 004B-1.

Jumo 004B-3 was an improved B-1, the major difference being the use of hollow blades turbine. It is important to underline that for most of the Jumo 004 wartime production it did not have hollow blades turbine (most source are completely confused on the issue), B-1 did not have them. Once mounted on B-3 the engine life doubled, to aprox 100 hours. Initially Jumo 004 engine life was 25 hours, with an overhaul at 10 hours, later increased to 50 hours, when proper usage and maintenance requirements were enforced. In the final months of war, when Jumo 004B-3 arrived, engine life reached 100 hours, which is more than remarkable - it was better than of many high powered German piston engines (which were more expensive btw).

Jumo 004C designated an improved Jumo 004B-3 with the same RPM range and engine life, but having the thrust slightly higher than of Jumo 004D (I read the numbers last night, somewhere around 2400lb thrust for C and around 2300lb thrust for D). Jumo 004C mounted on Me-262 brought a 50km/h increase in speed (930km/h). Serial production for this variant just started when the war ended.

Next it speaks of the D & E model having a fuel flow regulator to eliminate the notorious 'fuel dumping' problem. That got me to wondering how much of a difference such a device could have made [if it worked as advertised]. I read that Jumo-004B was bench tested to 100 hours with out failure and I was wondering if the fuel dumping problem was the prime reason for why operational engines got so low life [10-25 hours] BTW the author notes that in the hands of veterans, engine life doubled.

I wonder if the plans were for these to be mounted on future production Me-262/Ar-234?

Here the authors you quote seem to be confused. E and F variants were experiments of thrust augumentation - E used afterburning, F used water injection. They were only bench tested, no test flights were tried. The thrust was similar to C series, with an increase in fuel consumption.

I don't know what are you refering at when you say "notorious fuel dumping problem", Jumo 004 seems to be notorious in the literature for defects never present on the actual machines. If you are talking about the fuel starvation and satiation problems that plagued all early jet engines, then we have to mention that Jumo 004 was actually one of the least problematic, Germans having 10 years experience in fuel injection, Allies having none (it's truth though, Russians had one fuel injected aero engine operational during the war, but all German fighter and bomber engines used direct fuel injection, they were very experienced).

Confusion occurs from the fact that flame outs and engine fires often happened at engine start, but this was caused by the starter, which did not have the power to spin the engine to the idle speed. In order to allow Me-262 operation from airfields not specially prepared for it, they used a small starter, the Riedel engine, which did not have the power to spin the engine shaft up to 5000-6000 RPM, the idle regime. Post war jets did not have this problem simply because they needed large starters that could not be mounted inside the engine, thefore they were required to spin the engine up to idle speed, once starters became land based and weight was not an issue any longer. When the starter was turned off the burn was already stable, which cannot be said for Jumo 004 at 3000RPM.

However Jumo 004 had advantages over post war jets too. Most of the early jet engines had a fuel pressure gauge, to allow the pilot to regulate the fuel flow - the throttle linkage was directly connected to the pump. This is why early jets often had flame outs and engine fires. Jumo 004 on the other hand used an "all speed governor" from 6000 to 8700 RPM that automatically regulated the fuel flow. Of course this kind of governors did not solve all the throttling problems that jets had - until electronic control was introduced, jets had to be throttled with care, unlike piston engines.

Finally The Jumo 004H looks to be an interesting future replacement for double mounted Ar-234C models offering same thrust for 1/2 the number of engines and saving 1000kg as well!

G and H variants were enlarged Jumo 004 for competing in Class II jet engines (RLM divided jet engines in 4 thrust categories), the category where HeS 011 was the most likely to see service first, development being virtually ended. It is possible that G was already built, H was certainly not. Those engine doubled Jumo 004 thrust with an minor increase in dimensions (from 3.8m to 4m length, similar diameter).

Any one got a clue how much more fuel efficent and reliable these "turboprop engines" are and is there any way of figuring out how "4600 ehp" compares to jet engine thrust?

4600 ehp is equivalent shaft horse power, which means the exhaust thrust, which was significant for early turboprops, was converted into horse power for a certain speed.

Jumo 022 was according to Russian sources was rated to 4600EHP at sea level and static and 3500SHP and 1200 kgp at 800km/h (which is roughly equivalent with 7500EHP).

4600EHP at 100mph is roughly 9500lb thrust
7500EHP at 500mph is roughly 4500lb thrust

Jumo 012 between 6000-6400lb thrust at sea level depending on speed.

Note that the thrust of the turboprop varies significantly with speed, making them more suitable for high lift low speed planes, whereas jets are much more powerful than turboprops at high speeds, making them more better suited for low lift high speed planes. Turbofans are between these two extremes.

Turboprop variant of a jet engine (the way Jumo 022 was developed from Jumo 012) typically gives better range despite having the same fuel consumption at the core, but this does not happen always. However turboprops certainly give better lift capabilities, because of the large thrust at take off (cargo), and also better endurance (marine patrol).

Reliability was similar to their jets counterparts, typical for post war gas turbine engines. BMW 018 and Jumo 022, had seen extensive service in their (more or less close) descendants, SNECMA ATAR and respectively Kuznetsov NK12.

[Cantankerous]

the plane was first and mostly used in high altitude recon missions over Englad, yes, it flew..

Then Hitler decided he wanted a bomber, (if I recall correctly, it was nicknamed "blitzbomber or something like that) and all advantages in speed and endurance were lost to the bombload

another case of too litle, too few..
best regards

Xavier
Instandsetzungtruppfuhrer

Even though this thread is almost 20 years old, let me emphasize that the Ar 234 was only officially called Blitz, and that the Me 262A-2a fighter-bomber version of the Me 262 jet fighter was the aircraft called Blitzbomber in official wartime German documents. A March 26, 1945 directive signed by Hitler, while formalizing use of the name Blitz for the Ar 234, calls the Me 262 Sturmvogel, so Ar 234 was not called Blitzbomber at all.

[ewest89]

If you want to learn about the use of the Ar 234, get this:

https://www.chandospublications.co.uk/n ... cted-2020/

[Cantankerous]

If you want to learn about the use of the Ar 234, get this:

https://www.chandospublications.co.uk/n ... cted-2020/

Alternately, you can read about combat use of the Ar 234 in the book Arado Ar 234 Blitz: The World's First Jet Bomber. The title of the book for which you provide the link has the Ar 234's official name and "bombers" as separate words.

[critical mass]

The -004 D-4 is often given with 920 or 930 kp static thrust only. It differed from the B-3 (B-4) notably in addition of the BMW-003´s accelerator valve, to prevent too much fuel injection under low rpm (<6,000 rpm, i.e. starting the engine), which was a major contributor to short engine life due to burned out cans or turbine blades. Fuel regulation still is a major factor in increasing service life of the engines. Thus, unlike the -004B4, the -D4 allowed the pilot to use the throttles less constrained as the fuel flow was better regulated at high and low rpm and under high or low altitude.