B-17, B-24, or Lancaster

[renrich]

Milosh, I have two sources, "The Great Book of World War II Airplanes" and "Aircraft Of World War II" by Kenneth Munson. The Lancaster figures in one book show AC at mean weight, and the service ceilings are both 24500. One book shows service ceiling of B17 is 36000 feet. I expect that the service ceiling numbers are with typical load. They would vary a little depending on fuel load, because fuel is used outward bound and bomb load but I believe the numbers are accurate.

 

[syscom3]

The USSBS indicated that the higher you go, the lower your CEP, which had the perverse effect that 2 or 3 missions had to be flown to knock out the target.

The B17 flying at 30,000 feet might have been good for the survivability of the bomber and crew; but it was at the expense of what a bomber is supposed to do. Drop lots of bombs accurately.

 

[renrich]

I don't think there is any doubt that the higher the altitude the bombs are dropped from the more inaccurate the bombing will be in WW2. However, I don't think there is any doubt that the higher the bombers fly the harder for the Flak to bring them down and also the more difficult it is for altitude challenged fighters to intercept. The point is that the Lancaster was probably not as suited, for several reasons, as the B17 and B24 for daylight bombing.

 

[Milosh]

renrich, I was hoping you had a more authoritative source than those 2 books.

 

[RCAFson]

Bombing accuracy was a function of bombing altitude and bombsight design. The SABS sight on the Lancaster was extremely accurate. Here's an exhibition of truly pin point accuracy from 14000 ft :

Internet Archive: Free Download: RAF Sinks Tirpitz, 1944/11/22

The Lancasters that sank Tirpitz had to fly a ~2400 mile round trip with a 12000lb bomb load to the target.

The modded Lancaster 1 could carry the 22000lb Grand Slam to radius of 775 miles at a 15000ft cruise altitude with a 19000ft drop altitude. Total fuel carried was 1675 gallons and consumption was 720 gallons on the 775 mile outboard run and 620 gallons on the return 775 mile run. Take-off weight was 72000lb. Weight over the target was equivalent to the fully loaded gross weight of a standard lancaster. From a 1946 edition of Flight.

 

[syscom3]

Bombing accuracy was a function of bombing altitude and bombsight design. The SABS sight on the Lancaster was extremely accurate. Here's an exhibition of truly pin point accuracy from 14000 ft :

Internet Archive: Free Download: RAF Sinks Tirpitz, 1944/11/22

The Lancasters that sank Tirpitz had to fly a ~2400 mile round trip with a 12000lb bomb load to the target.

The modded Lancaster 1 could carry the 22000lb Grand Slam to radius of 775 miles at a 15000ft cruise altitude with a 19000ft drop altitude. Total fuel carried was 1675 gallons and consumption was 720 gallons on the 775 mile outboard run and 620 gallons on the return 775 mile run. Take-off weight was 72000lb. Weight over the target was equivalent to the fully loaded gross weight of a standard lancaster. From a 1946 edition of Flight.

The Norden bombsight was also accurate for its day. At 19,000 feet, it accomplished the same as the SABS.

 

[Shortround6]

As far as the service ceilings go. they are going to be very affected by the weight of the aircraft. see the flight manual posted here on this site:
http://www.ww2aircraft.net/forum/other-mechanical-systems-tech/b-17f-g-manual-one-piece-22716.html

See page 80 for climb rates a various altitudes and weights. also see page 98.

I imagine that the B-24 and Lancaster had similar charts and trade offs so when comparing it would be good to specify under what conditions the comparison is being made.

Service ceiling was usually defined as the altitude at which the plane could still climb at 100ft per minute (or close metric equivalent?). A B-17 that took of at 65,000lbs and burned off 8000lbs of fuel was going to have a lot of difficulty getting anywhere near 35,000ft.

 

[Waynos]

Ren, none of the allies heavies were particularly suited to daylight raids. US losses before the advent of long range escorts were every bit as horrendous as the RAF had told them they would be, that was why the RAF switched to night bombing and they regularly pleaded with the USAAF to make the same switch (by 'they' I mean Harris).

The US heavies were, perhaps better adapted to the day assalult by carrying less bombs (typically about half the average Lancaster load) and more machine guns. Maybe this is why they could fly higher? There were plans to make high altitude Lancs which involved only the removal of the front fuselage and replacement with a pressurised cabin (akin to the Wellington VI prototype) but this was never pursued to the hardware stage so, if it could fly so high that a pressure cabin might be needed, albeit with a lesser bomb load, there was no physical reason the Lanc could not match the US types for altitude, if required to, as far as I can see?

In a chapter referring to Tiger Force that I was reading recently there was a passage where a senior RAF officer was bemoaning the fact that the US seemed not to be able to appreciate just what the Lanc could do. In comparison with the B-17 and 24 he writes that neither of them could take off with an 18,000lb load from a 6,000ft runway, he also writes how the Lanc could carry a higher load of incendiaries than even the B-29. He explained how, if anyone is interested I'll scan that particular passage and post it up. Its nothuing earth shattering, but I found it quite interesting.

 

[RCAFson]

In a chapter referring to Tiger Force that I was reading recently there was a passage where a senior RAF officer was bemoaning the fact that the US seemed not to be able to appreciate just what the Lanc could do. In comparison with the B-17 and 24 he writes that neither of them could take off with an 18,000lb load from a 6,000ft runway, he also writes how the Lanc could carry a higher load of incendiaries than even the B-29. He explained how, if anyone is interested I'll scan that particular passage and post it up. Its nothing earth shattering, but I found it quite interesting.

I would certainly be interested.

 

[RCAFson]

The Lancasters that sank Tirpitz had to fly a ~2400 mile round trip with a 12000lb bomb load to the target.

BTW, on a earlier mission, 3 Lancasters flew back to base with their 12000lb tallboy after the Tirpitz was obscured. 2400 miles carrying the bomb the whole way.

 

[Waynos]

Here is the snippet, the officer in question was Air Marshall Sir Hugh Lloyd, and these are his own words and the extract is from page 499 of 'Lancaster' by Leo McKinstry, which has first hand accounts like this all the way through it from every aspect of the Lancasters history.

 

[FLYBOYJ]

That's good info Waynos, but as explained many times before, that's all in the bomb racks which could be removed, modified, and reconfigured and has little to do with the aircraft.

I question the runway length argument - that depends on fuel and bombload and there's a lot of variables built in there.

 

[FLYBOYJ]

RCAFson - you share a common IP with a FORMER member - dunmunro1. Please explain...

 

[ppopsie]

World War II Pilots

As a citizen of an ex-enemy nation I admire all three and as an airplane nuts I love all of them. I read and enjoyed the story listed above and the one titled "Wild Blue" a story of McGovern by E. Ambrose which was fully translated into our langage. Who said the B-24 was inferior to the B-17? What happened if we got one like the one of these in the war (plus petrol).

 

[DerAdlerIstGelandet]

RCAFson - you share a common IP with a FORMER member - dunmunro1. Please explain...

And the fact that he registered shortly after the other guy was banned...

Someone is playing you for dumb.

 

[FLYBOYJ]

And the fact that he registered shortly after the other guy was banned...

Someone is playing you for dumb.

Maybe naive, but never dumb!

 

[Lucky13]

Are we dealing with a split personality you say?

 

[Demetrious]

The Lancaster had a service ceiling of 24500, the B24 had a service ceiling of 28000 feet, the B17 had a service ceiling of 35000 feet. Which was most survivable against the heavy bomber's arch enemy, Flak?

I am quoting this post because it deserves to be re-iterated.

As for pin-point accuracy at angels 14 or even 19, that's no surprise. The Norden and it's British equivalent were marvelous technological devices more then capable of that accuracy. The reason daylight precision bombing was less then precise was because attacking at 15-20K in daylight with no fighter escort was tantamount to suicide. Consider the damage inflicted- and the horrendous losses received- by the B-24 low-level raid on Polesti.

Accuracy went to hell when you attacked from 30,000 feet- but by the same token, 30,000 feet was HIGH for the day. Enemy interception was greatly impeded and flak accuracy was reduced, and only the 88mm guns could reach you, as opposed to 40mm and up at mid-altitudes. The ability of the US to put armadas of hundreds of aircraft into the air also rendered the whole issue of accuracy somewhat moot, since everything within four square miles was obliterated.

Daylight vs. Night bombing- in the earlier days of the war, daylight bombing was obviously more effective. However, the British continued to develop remote-guidance technology (first used against them by the Germans in the 'Battle of the Beams') to the point where eventually British night bombing became more accurate then American daylight bombing.

Of course, long-range escorts were coming into their own at that point. In the early days, daylight bombing offered an offensive power available nowhere else.

 

[Waynos]

That's good info Waynos, but as explained many times before, that's all in the bomb racks which could be removed, modified, and reconfigured and has little to do with the aircraft.

I question the runway length argument - that depends on fuel and bombload and there's a lot of variables built in there.

I think he was speaking more in terms of internal volume, rather than the racks (of which the B-29 is said in the quote to have more than the Lanc, but the bombs accomodated int he Lanc were bigger) But that is just my interpretation of what was said.

Regarding the runway length, what sort of variables come into play with what is, I feel, a clear cut statement, that neither the B-17 or 24 could take off from a 6,000ft runway with a load of 18,000lb of bombs?

Are you saying that they could if they were not carrying any fuel?

 

[FLYBOYJ]

I think he was speaking more in terms of internal volume, rather than the racks (of which the B-29 is said in the quote to have more than the Lanc, but the bombs accomodated int he Lanc were bigger) But that is just my interpretation of what was said.

The key word was "hooks." If you listen to what he says you're talking about 800 pounds of additional incendaries.

Regarding the runway length, what sort of variables come into play with what is, I feel, a clear cut statement, that neither the B-17 or 24 could take off from a 6,000ft runway with a load of 18,000lb of bombs?

Are you saying that they could if they were not carrying any fuel?

You would have to do the math with data from performance charts and also consider what kind of head wind (if any) was available. It's obvious that the B-17 or B-24 isn't carrying that kind of bomb load, but I don't see where runway length would be a player in the way the war actually turned out.