I'm replying to claims that the Lancaster VI had unreliable engines.
The Lancaster as a potential nuclear bomber in 1945
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I'm replying to claims that the Lancaster VI had unreliable engines.
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Based entirely on conjecture and massive leaps of faith. You've ignored the fact that increasing the Lanc VI's MTOW to be able to match the range and load figures would incur a considerable degradation in performance. This is why your entire scenario is based on fiction. You keep posting figures for the Lancaster VI, yet they are figures of a standard aircraft unencumbered by the modifications made to increase its MTOW etc, which nullifies your entire argument. The Lanc Specials had a lot of mods to reach an MTOW of 72,000lbs and that impact meant that their altitude, their range and their speeds were all lower, and this somehow has escaped you, despite being repeatedly advised of it in this thread.
Regardless of the unreliable engines, the Lancaster VI, just like any other Lancaster would have been too low, too slow and not enough range to have flown the missions, let alone been able to carry the Fat Man, which, again, there IS NO EVIDENCE that Chadwick said the Lancaster could carry a Fat Man bomb, so just fantasy, and as long as that distinction is made, then that's okay, you can fantasise about any scenario you like.
The only major mods on the Grandslam Lancaster Specials were strengthened landing gear and removal of the mid upper turret, and of course removal of the B-B doors to sling the bomb externally ( yet cruise speed, and AMPG was similar to a standard Lancaster at the same weight). Otherwise they were pretty much as any other Lancaster I. of course they had to reduce fuel load to accept a 22000lb bomb, but with a 10K lb bomb 12000lb of fuel can be added to the aircraft. All aircraft, including the B-29, will have lowered performance including ceiling, and will have restricted handling when operating at very high TO weights. Of course, as per the B-29, much of the fuel load will be burned off during the overwater flight to Japan, and so by the time the aircraft enters a combat zone, it's weight will be reduced considerably, increasing its performance and it will be able safely execute maneuvers needed for combat.
The data on Lancaster performance is available and it clearly shows that the Lancaster was mission capable. Why you continue to claim otherwise, when the data is online:
Lancaster Performance Trials
, showing you to be incorrect, is a bit of a mystery.
As far as I can see the Lancaster is suited to carry the Little Boy bomb but would struggle with Fat Man. By November 1946, i.e. just over 1 year after Nagasaki Oak Ridge was producing 3.5kg/day of U235 which is enough for one Little Boy every 3 weeks. Production at the end of 1945 must have been enough for 1 bomb every 2 months. Hence the solution would be to use the Lancaster VI only for Little Boy.
More concerning is the performance. The Lancaster VI had a cruise speed of 278 @ 24,000ft with a service ceiling of 28000ft. The maximum speed is unclear to me from this report but may only be 312mph with radiator flaps closed at 18000ft though one line is drawing at 324mph Can someone interpret the graph for me?
http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_VI_JB675_Performance.pdf
The Ki-84 had a maximum speed of 424 mph at 23,000ft with a service ceiling 37000ft. (Wikipedia) so the aircraft seems vulnerable. Little boy was dropped at 0800 or so, ie daylight.
A gain of 12mph is possible by deleting the dorsal turret.
More concerning is the performance. The Lancaster VI had a cruise speed of 278 @ 24,000ft with a service ceiling of 28000ft. The maximum speed is unclear to me from this report but may only be 312mph with radiator flaps closed at 18000ft though one line is drawing at 324mph Can someone interpret the graph for me?
http://www.wwiiaircraftperformance.org/Lancaster/Lancaster_VI_JB675_Performance.pdf
The Ki-84 had a maximum speed of 424 mph at 23,000ft with a service ceiling 37000ft. (Wikipedia) so the aircraft seems vulnerable. Little boy was dropped at 0800 or so, ie daylight.
A gain of 12mph is possible by deleting the dorsal turret.
The service ceiling is at 65000lb. Actual weight at the start of the bomb run would be ~55000lb due to fuel burn. Historically, Enola Gay dropped at 31060 ft (corrected from 30700) and 328mph TAS as per her log, Bockscar dropped at ~29K ft.
Maximum speed is 313mph at 18300ft and is given on page 4. There was some additional speed gain possible via deletion of the front turret. The other factor is that Merlin 86 engines could have been substituted (used on the Lincoln for high altitude variants), and these raise FTH by ~6000ft.
The line to the right of the maximum speeds graph shows boost levels.
Tests showed that carrying the Grandslam externally had little impact on speed. Cruise speed went from 214mph (4.6lb boost at 2350rpm) to 212mph (4.5lb boost at 2350rpm). A carefully faired FATMAN installation, along with turret deletions and a cleaned up airframe should minimize speed loss. The addition of fuel injection in place of carburetors would also help.
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Thanks, I'd originally misread the curves and assumed a speed of about 328 @ 24,000ft. With deletion of the dorsal turret a cruise speed of 292mph @ 24,000ft is possible. With fuel burn loss its probably possible to cruise at 292mph @ 27,000ft, perhaps a little higher. I would be reluctant to delete the front turret given the Japanese tactic of head on dives to deal with the B29 speed and altitude.
A quick scan of Japanese fighter types reveals that most could not exceed 360mph @ 6000m/20,000ft. The exceptions were the Ki 44, Ki 84, N1K1-J. (they did have improved turbo chargers and better superchargers under development but its nothing like a Ta 152)
- Ki 44 Maximum speed: 605 km/h (376 mph, 327 kn) at 5,200 m (17,060 ft)
- Ki 84 Maximum speed: 682 km/h (424 mph, 368 kn) at 7,000 m (23,000 ft)
- (N1K1-J) Shinden Kai Maximum speed: 656 km/h (408 mph; 354 kn) at 6,096 m (20,000 ft)
So our Lancaster is more vulnerable than a B-29 that can achieve 358mph @ 25,000ft and likely 360mph at 30,000 ft with the ventral and dorsal turrets removed and is beyond practical interception capability.
Fat Man was dia 1.5m x 3.3m long so with an area of 1.766 sqm. I suspect a Cd of about 0.1 which would degrade to 0.2 if half in the slipstream.
at 120m/s speed an air density of about 0.4kg/cubic meter seems to generate about 1272 newtons of drag that would take 152kW (about 200hp) to overcome. The drag is probably about the jet thrust one of the merlin's was producing. The engines are at about 1/2 power (so a total 4 x 1000Ho=4000hp) so we are loosing 5% maybe 10% so with a cubed law we are going to loose about 1.8% speed. Very rough calculation. I could be off by 100% in which case the speed drop is more like 3.3% (12 mph) about the same as turret deletion would gain.
Deleting the rather big dorsal turret compensates for Fat Man in a distended streamlined belly.
The risk to the bomber being shot down would be considerable unless it were part of an escorted formation.
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Twin .303mgs are probably a poor defense against head on attacks and I'd trade that for a speed and altitude gain.
The Merlin 86 produced 1440hp at 22250ft versus 1580hp at 16000ft ( 18300ft with ram air) for the Merlin 85, so there would be an improvement in higher altitude performance but it's not going to match a B-29.
There's no particular reason not to bomb at night.
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Do you have any further information on the Merlin 86? Sadly my "Merlin every Mark every variant" is missing. Did it use a larger impeller, faster gear or have a 3rd gear?
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Impeller is identical to Merlin 85 (12 and 10.1in) reduction gear was .42 but F.S gear ratio goes from 7.06 to 8.03 on the Merlin 86. M.S gearing was identical at 5.79.
Merlin 24 TO HP = 1610
Merlin 85 TO HP = 1635
Merlin 86 TO HP = 1605
Dash119
Senior Airman
I can think of two, precision of delivery and observation. Bombing by RADAR was a last resort, due to reduced accuracy. Keep in mind these weren't just any bombing missions, these were also tests of new and radically different weapon systems. Observation of the weapons delivery, ignition and immediate effects was almost as important as the delivery of the weapon itself.
Since bombing at night would be safer in terms of enemy interference, and was within the capability of the B-29 I wonder why both bombs were dropped in daylight...
The IJ air defense system was almost non-existent by August 1945 and both historical missions could have been intercepted by a competent GCI controlled fighter force, by existing IJAAF fighters:
http://www.wwiiaircraftperformance.org/japan/Jack-11-105A.pdf = 375MPH at 30K ft.
http://www.wwiiaircraftperformance.org/japan/Ki-84-156A.pdf = 400mph at 30K ft.
If the bomb had been ready a year earlier do you think they would have dropped in daylight? German targets would almost certainly have been hit at night.
Coastal cities provide good radar returns and allow for accurate radar bombing. Bockscar was going to drop by radar and almost did. The photoflash effect of the bomb would actually have allowed for good initial photography, but the main analysis of bomb effects was done by follow up missions because the bomb blast and smoke obscured the target anyways.
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Interesting discussion on Ki 84 performance here. Ki-84 - The Real Maximum Speed?
It's not as high as usually indicated due to derating of the engine while reliability issues were addressed. The B29 can pull away from a Ki 44 at 30,000ft.
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OK, but the fact is that the TAIC numbers were what the USAAF were working with in August 1945. It seems that they didn't think the IJAAF had the capability to intercept the A-bomb missions, even though their own data stated that the IJAAF had aircraft with the needed performance.
FLYBOYJ
"THE GREAT GAZOO"
You can debate the safety of a night attack with regards to enemy interference, overall it is safer to actually fly in the daytime although they took off in the middle of the night. Also consider there were many who wanted to witness the bomb going off and the aftermath and although there would have been a hell of a night time glow.
swampyankee
Chief Master Sergeant
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- Jun 25, 2013
Somewhere, I've read that, in Europe, the RAF night bombers were demonstrating about the similar or possibly better accuracy when compared to USAAF day bombers by mid to late 1944, so the accuracy argument may be moot.
I think it's also likely the USAAF did not consider Japanese air defenses to be a significant threat: both nuclear attacks were unescorted, day attacks. The choice of day attack was for damage evaluation and, possibly, to catch more people in the open.
I think it's also likely the USAAF did not consider Japanese air defenses to be a significant threat: both nuclear attacks were unescorted, day attacks. The choice of day attack was for damage evaluation and, possibly, to catch more people in the open.
special ed
1st Sergeant
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- May 13, 2018
I have looked for some time for my book on Silverplate and it remains lost in the magic trash pile, so I will have to use my faulty memory. The work up with B-29s began at Wendover, Utah, and took constant flying for nearly a year to develop the delivery flight profile. The 509th was subject to absolute secrecy. Some men were dismissed from the program for loose lips. Once at Tinian, there were comments about the 509th being a gold brick outfit because they didn't fly mission with the others. The 509th always seemed to be flying 3or 5 plane missions with no losses or damage. Now imagine if the 509th showed up with Lancasters on a island of B-29s. The troops would say "What the hell is that?" The Japanese would say "What the hell is That?" And any imbeded reporters would wonder "What the hell is that?" It would have been like hiding a mule in a herd of horses.
Dash119
Senior Airman
I agree that it is safer to fly a plane in the daylight rather than at night, and clearly a takeoff in daylight is safer than one at night. My point was that enemy observers, flak and fighters would be at a disadvantage at night, so from that standpoint the mission would have been safer if flown after dark when over enemy territory.
FLYBOYJ
"THE GREAT GAZOO"
Agree about being a harder target at night for sure.
Dash119
Senior Airman
Actually I have read that by flying just a few airplanes on each mission the Japanese air defenses would ignore them in favor of the large formations. Single plane weather/reconnaissance missions were often just ignored by the Japanese air defenses and people. One of the Japanese survivors from Hiroshima recalled seeing Enola Gay, but was not concerned because it was a single plane.
Dash119
Senior Airman
I believe the original point was that the B-29 has such insurmountable problems that it never comes online. We have to use the Lancaster because that is the only choice available.
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