Step 1 - Orignal Lancaster bomber bluprint alongside modified Original Lancaster Lancaster bomber blueprint. Blueprint for original Lancaster bomber
Modified
MODIFICATION OF THE AVRO LANCASTER B In order for the Lancaster to carry the bomb, the original plane needed to be modified. 23 Lancasters were modified however only 19 were used in the final mission.The mid upper gun turret and the bomb bay doors were removed to make space for the callipers to hold the bomb and a motor to spin it. A twin set of spotlights were fitted to measure how high the plane was flying. Finally a VHF radio was fitted so all the bombers could communicate also allowing Gibson to personally direct the raid.
d Lancaster
Blueprint for modified Lancaster bomber
PRECISION The dambusters mission was deemed so difficult the mission was almost not authorised. The Lancaster bombers had to fly at specific heights and speeds for the bouncing bomb to fall correctly. Due to the low fly height of the bombers, on board instrunments wouldn’t work. To find the height of the plane the twin spotlights were directed so when crossed on the water it would indicate the craft was at 60ft. A crew member would communicate with the pilot to either go up or down.To find the distance between the craft and the dam a crew member would use a wooden instrument so when the dam fit between the prongs it was time for the bomb to be released.
SPINNING In order for the bomb to project forwards towards the dam the bomb had to be spinning in that direction before it was released from the Lancaster. Once the bouncing bomb reached the correct RPM of 500 it could be dropped once the aircraft had reached the correct distance from the dam and the water.
CYLINDRICAL VS SPHERICAL
Originally the bomb was constructed as a sphere but Barnes realised it was much more efficient to create a cylindrical version of the bomb.The bomb was constructed to be 50 inch in diameter and 60 inch long.
WATER RESISTENCE
It was at this stage of the bombing that the design of the bomb really took effect.The weight, size and shape of the bomb needed to be specific so that the bomb would bounce and not sink.The design of the bomb displaced so much water upon impact that it created enough resistance for the bouncing bomb to then move upwards from the surface of the water and because the bomb was spinning it would then be projected towards the dam.
NETTING WATER RESISTANCE To protect the dams from attacks, the Germans installed netting that would prevent incoming missiles fired from submarines.This was the reason a new bomb had to be designed to counter this defensive measure. Because of the number of nets, specific timings had to be used to ensure the bomb would bounce between the nets and not get caught.
Once the bomb hit the water and the displaceme process has taken effect, t spinning of the bomb will project it forwards toward the damn. It was crucial t the bomb would bounce multiple times across the surface of the water to av the torpedo netting .
ent the l ds that
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DEP
The bomb w explode upo the wall and the most am them. The bouncin bomb would the bomb w time for the bottom of t
PTH CHARGES
wasnt supposed to bounce across the water and on impact with the wall. Instead it was designed to hit d fall to the bottom of the bank where it would inflict mount of damage to the dams and hopefully breach
ng bomb had depth charges set to 30m so that the d explode when it reached the bottom. Upon failure was set with a 90 second timer which was plenty of e bomb to bounce across the water and fall to the the bank.
MOHNE DAM
Flight height - 60ft Aircraft speed - 220mph The bombers had to approach the dam from over land which rose to 160ft.This provided some cover from oncoming fire. Once the bomb had been released the crafts had to make hard rights to avoid more flak from the left.
EDER
Flight height - 6 Aircraft speed The aircraft had approach throug surrounded valle had to go over a before having to the correct amo releasing the bo bomb was relea lancasters had t incline to miss t lies behind the d
R DAM
60ft 220mph d a night time gh a hill ey.The aircraft a 50 ft spit of land o alter altitude to ount before omb. When the ased the to make a sharp the 300ft hill that dam.
SORPE DAM Flight height - 60ft Aircraft speed - 180mph The bomb was dropped from the aircraft without spinning due to the shape of Sorpe dam. Due to this different approach the bombing mission in fact failed and only damaged the dam without breaching it.The bomber had to fly over a 180 ft hill and after the bomb was dropped it had to rise to avoid another 300 ft hill.