What technology existed in 1940 that could have been used to provide better targeting guidance for Barnes Wallis's earthquake bombs? At night and through cloud?
Keynes' Cruisers Volume 2
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What technology existed in 1940 that could have been used to provide better targeting guidance for Barnes Wallis's earthquake bombs? At night and through cloud?
The B-29 had a radar used for final target acquisition as well as some use in navigation. Flying at night the radar would be perfectly adequate to find the target if you are going after a city. Many German cities had features such as rivers (crossed by bridges with strong radar returns) which would be adequate for an aiming point for an atomic weapon.
Though a 2 ton "Small Slam" would have been much easier to develop and cheaper to build than the 5 ton "Tall Boy" (let alone the 10 ton "Grand Slam") it would still have been initially in short supply. IMHO they would be used initially by a small number of "sniper squadrons" (as OTL by 617 and 9).
For such units Operational and training issues were just as important as technology. Post the Dam raids but before Earthquake bombs became available, 617 carried out a number of precision raids at night where electronic aids were of little significance e.g attacks on French factories supplying the Nazis at Limoges, another at Albert and an even tighter site at la Ricamerie. it is true that some raids were called off or aborted due to weather in this period but IMHO that policy should have been wider used anyway.
Even when Tallboy become available, the first raids were at night not using Gee, Oboe or H2S though they did have the advanced Stabilized Automatic Bomb Sight. This had been invented in 1941 at Farnborough. It was a tachymetric sight equivalent to the Norden but simpler and cheaper. None the less it was judged unsuitable for mass deployment by Harris because it did not suit BC Bomber stream tactics. Like the Norden it required a somewhat longer fixed approach by the aiming aircraft.
Cochrane persuaded his superior to try it on a small scale. For a small precision strike, the SABS resulted in spectacular accuracy e.g. the famous Saumur Tunnel attack in support of Overlord and an later attack on a rail junction in Paris (both at night). However even SABS was less effective when used with light case bombs e.g. in raids on the Antheor Viaduct where the largest 12Klb version did no damage despite dropping within yards,
It was the combination of better accuracy and an earthquake bomb that really made a difference in late 44 and IMHO would have done the same in late 41/early 42 even in small numbers. Once Small Slams could be mass produced and used by the main force the effect would have been multiplied. Consider how BCs effectiveness grew when other better weapons were introduced whether light case, MC and incendiaries.
The Small Slam could not have hit truly giant targets but was a beginning. By '43 The Snipers would have moved on to larger earthquake weapons and more hardened targets.
In addition in OTL part of the technique 617 developed to improve their accuracy was low level marking of the targets . Once again the method was perfected in smaller raids against less well defended targets in late 43 and early 44 e.g. an aircraft plant at Toulouse and a major Nazi airbase at St Cyr. Note: that for such French targets the accuracy was important both for the effect and to reduce possible friendly civilian casualties.
However this method could be applied to much larger formations including aircraft lacking SABS.
iOTL 617 began helping the Pathfinders mark and light a series of targets during the campaign vs rail hubs in spring '44. This started in France, moving to Germany. Blind bombing aids were only to be used if there was ttal cloud coverage.
This series culminated in a raid on the heavily defended marshaling yards at Neuhausen, a mile west of the Hauptbahnhof in Munich. Cochrane evaluated that one attack as doing many times more damage than all the previous attempts over 2 years.
Clearly an earlier introduction would have helped BC.
Note: Cheshire eventually decided that lighter, faster aircraft were better suited for low level marking. By night he began using Mosquitos and eventually by day using Mustangs loaned by the USAAF. This proved important when 617 was switched to day attacks on V weapon sites and then escorted raids into Germany.
Again that might have seen wider application.
Aside: apologies for multiple edits. hand eye coordination shot again
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I have been summoned....
Yes and no - H2S was pretty useless over the Ruhr and over Berlin, the mass of ground returns swamped the screens, other cities had a very low contrast making them difficult to find, others were protected by their terrain, Stuttgart for example, as it was built in a series of hills and valleys, was almost impossible to locate on H2S.
B-29 radar in 1945 is a different kettle of fish from anything BC ever had, bridges did not show up well on HS2, at least not on the ones in service, there was an experimental low level H2S being trialled in 1945 that gave much better resolution but it never entered service. The only cities that really showed up well on H2S were coastal cities with distinctive coastline features.
BC blind bombing with H2S was lucky to achieve 2-3 miles CEP, the improvements in blind bombing accuracy that Bomber Command achieved in late 1944 and early 1945 were more to do with navigational improvements than with H2S - it remained a difficult to use device up until the end of the war.
If you want to blind bomb with H2S accurately you need the equipment fit of the V Bombers - H2S MK IX and the electro mechanical Bombing Navigation System.
It is interesting to note that RAF BC V Force held bombing and navigational competitions similar to SAC in the 50's and early 60's - and while the winning scores were often measured in hundreds of yards, the average scores were measured in several miles.
There is also the simple matter that many targets don't actually show up all that well on analogue radars with little video post processing of the return images. SAC called these targets 'non cooperative' targets.
This plagued SAC from the 50's to the 70's - huge numbers of strategic targets were planned to be bombed from 'radar offsets', even cities, during Linebacker II 100% of targets for (conventional) bombing were via radar offset for example, often using the same aiming point, a hill outside Saigon for example and a point on the river delta for Haiphong.
TL : DR radar bombing in the 40's is not the radar bombing of today, and you would need a better H2S than what was available.
Yes and no - H2S was pretty useless over the Ruhr and over Berlin, the mass of ground returns swamped the screens, other cities had a very low contrast making them difficult to find, others were protected by their terrain, Stuttgart for example, as it was built in a series of hills and valleys, was almost impossible to locate on H2S.
B-29 radar in 1945 is a different kettle of fish from anything BC ever had, bridges did not show up well on HS2, at least not on the ones in service, there was an experimental low level H2S being trialled in 1945 that gave much better resolution but it never entered service. The only cities that really showed up well on H2S were coastal cities with distinctive coastline features.
BC blind bombing with H2S was lucky to achieve 2-3 miles CEP, the improvements in blind bombing accuracy that Bomber Command achieved in late 1944 and early 1945 were more to do with navigational improvements than with H2S - it remained a difficult to use device up until the end of the war.
If you want to blind bomb with H2S accurately you need the equipment fit of the V Bombers - H2S MK IX and the electro mechanical Bombing Navigation System.
It is interesting to note that RAF BC V Force held bombing and navigational competitions similar to SAC in the 50's and early 60's - and while the winning scores were often measured in hundreds of yards, the average scores were measured in several miles.
There is also the simple matter that many targets don't actually show up all that well on analogue radars with little video post processing of the return images. SAC called these targets 'non cooperative' targets.
This plagued SAC from the 50's to the 70's - huge numbers of strategic targets were planned to be bombed from 'radar offsets', even cities, during Linebacker II 100% of targets for (conventional) bombing were via radar offset for example, often using the same aiming point, a hill outside Saigon for example and a point on the river delta for Haiphong.
TL : DR radar bombing in the 40's is not the radar bombing of today, and you would need a better H2S than what was available.
Story 1892
Panama February 1, 1943
USS Essex slowly moved forward. The large ship was moving at a walking pace. Seven minutes later, the lock was empty. Two hours later, her escorting destroyers were also clear. They pulled in to refuel at the navy docks. By noontime the five warships were at sea and heading to Hawaii.
USS Essex slowly moved forward. The large ship was moving at a walking pace. Seven minutes later, the lock was empty. Two hours later, her escorting destroyers were also clear. They pulled in to refuel at the navy docks. By noontime the five warships were at sea and heading to Hawaii.
Driftless
Donor
So the Essex will shortly be in theater, functionally to replace the Saratoga. I would imagine there will be some caution about getting her blooded with limited risk operations.
I believe there are also two CVL's working up in the Caribbean as well.
What's the next American Battleship(s) to replace South Dakota in the Pacific?
I believe there are also two CVL's working up in the Caribbean as well.
What's the next American Battleship(s) to replace South Dakota in the Pacific?
Indiana Beach Crow
Monthly Donor
"We have a deal running right now where if you buy ten, you get the eleventh one free."
US Navy: "I'll take twenty."
Bit of a red herring there ... or should it be "pink elephant"
Conceived in 1943 by the British Navy specifically as an "concrete piercing" weapons to attack U Boat pens.
It was therefore way too late for the timeframe of the POD
(though I suppose it might have been started earlier if the 3" rocket motor had also been conceived earlier)
It weighed 4000lbs but only carried 500lbs of explosive (the rest being the rockets and armoured cap).
Even my proposed "Small Boy" roughly the same size would have around 1500 lbs of explosive.
Tallboy had weighed only 3 times as much but carried 10 times the explosive.
Grandslam 5.5x the weight for 22x the bang.
This smaller charge meant a Disney needed a direct hit to do damage
unlike BWs earthquake bombs that were designed for "near misses"
They worked by the earthquake effect or even a "hangman's drop" under the foundations.
This is very well seen at two of the famous V sites ... V-3 supergun at Mimoyeques and the V-2 depot at La Coupole.
BTW :There is a conversation reported in several books between BW and Cheshire where the inventor advises that the new bombs should be aimed around 20yds from a large concrete structure to undermine the foundations.
The fact that Tallboy and Grandslam did penetrate so well was a bonus not a design aim
which is why Disney was originally conceived, later given priority by the British but never in fact used by them.
The only operator was the USAAF who at the time could not touch these fortified structure.
Aside: the same problem caused them to try the disastrous "Aphrodite" radio controlled Kamikazes
which killed Joseph Kennedy Jr when one exploded before the crew needed for takeoff could bail out
USAAF deployed 2 Disneys in under wing pylons of a few adapted B-17s and staged small raids
but in total only 158 devices were ever dropped in the ETO to almost no effect.
(none were ready for PTO before VJ day)
Disney was rocket boosted to get better penetration but in consequence had erratic fall characteristics.
It was LESS accurate than conventional AP bombs let alone BWs designs, which were spin stabilised.
The concept of a high level unguided rocket assisted penetrating bomb was not a success in WW2.
That needs effective precision guidance as we have today.
So again I don't estimate even an "early Disney" would have useful ...
as in OTL cool
but not worth the trouble as compared to an early "Small Slam"
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Random question- would a rocket propelled, spin stabilised AP bomb work? I’m thinking rocket ignites after the bomb has got to almost its natural terminal velocity.
Would likely only cause the bomb to have increased CEP.
Same reason why RAP shells were not practical until the 70's/80's - rocket propellant technology advances added to electronic miniaturization.
I recall that the Tall boy and Grand slam also benefited from a very predictable 'drop'
It was noted that the bomb did not wobble for example or vere off like smaller bombs and would be less likely affected by wind shear
Also the crews dropping them were among the best and most experienced in the game
All of which contributed to the very good CEP that the weapons experienced in operation
It was noted that the bomb did not wobble for example or vere off like smaller bombs and would be less likely affected by wind shear
Also the crews dropping them were among the best and most experienced in the game
All of which contributed to the very good CEP that the weapons experienced in operation
Designed to have a very high terminal velocity and the fins were canted so they were spinning just as it they were fired from a rifle. Combined with the weight it gave the same advantage as a rifle bullet to a musket ball in terms of accuracy.
The Tallboy was not designed to go through a mass of concrete. The best effect was for a very near miss and the explosion occurring under the target. I was originally under the impression that the Grand Slam was just a bigger version however there is at least one article that posits that they were designed to penetrate concrete.
Both Tallboy and Grandslam were given the MC nomenclature by the RAF (Medium Capacity), neither were referred to as SAP (Semi Armour Piercing). Grandslam was given a slightly thicker case and it was subjected to a special oil hardening treatment to improve its effectiveness against heavily armoured targets.
However, for all the publicity that both get for use against U-Boat pens and V-Weapons bunkers etc. the BEST USE of these weapons was against railway viaducts, canal viaducts and bridges. The campaign in March 1945 against railway viaducts in northern Germany finally paralysed transport in the 3rd Reich. Forget sexy targets, forget oil, the jugular of the 3rd Reich was rail and canal transport, and the viaducts and bridges that dotted northern Germany were the critical vulnerability of this system.
The latest comments about strategic bombing encouraged me to post a new thread about a highly speculative way to develop an early all weather precision guided bomb. I made a new thread because it's a long post and I didn't want to derail @fester thread anymore than the normal amount.
https://www.alternatehistory.com/fo...arthquake-bombs-and-tarzon-with-radar.460873/
https://www.alternatehistory.com/fo...arthquake-bombs-and-tarzon-with-radar.460873/
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