- Yes
- No
De Havilland DH 98 Mosquito B Mk.IV "Highball"
Vehicle History and service history:
During the development of the Highball Anti-shipping weapon, a suitable airframe platform had to be established. The logical choice was to utilise the already existing DH 98 Mosquito B Mk.IV, as it possessed both the speed and handling to make it suitable as a naval strike platform for the new weapon. The integration of the Highball bomb system wasn’t as simple as just enlarging the bomb bay, though, and serious modifications were required to the normal release mechanism, as unlike conventional bombs, Highball needed to be span up to speed prior to release from the carrier aircraft, to ensure it behaved correctly after release.
The Highball itself was a spherical bomb, with flattened sides, filled with around 600lbs of its 1,280lbs of weight being composed of Torpex. The weapon was detonated by a shot from a hydrostatic pistol set to fire at a depth of around 27ft, causing it to cause massive damage to the targeted vessel below the waterline. Due to the Highball needing to be spun backwards at around 700-900 rpm, a special fairing was fitted within the converted bomb bay of the MK.IV, which was powered by a ram air turbine mounted centrally in the bomb bay, with an extendable air intake. In this configuration, the Highball was then dropped from a maximum altitude of 60ft at a speed of 360mph, allowing the bomb to skip towards the intended target like a tossed stone, similar to the Upkeep weapon used during Operation Chastise.
The system required a lot of testing to get the spin and speed correct, and it was found that releasing both Highball bombs from the same aircraft with a 1 second delay was the best method of delivery for the bomb. The main testing took part in the first half of 1944, against the battleship Malaya, with one inert bomb actually punching a hole in the side of the battleship, albeit accidentally. Happy with the results of the testing, and the suitability of the delivery system, 27 Mosquito B Mk.IVs were converted for special operations and assigned to No 618 squadron RAF , with their intended target being the German battleship Tirpitz, under the code name Operation Servant. Delays in the development of the Highball scuppered this plan though, and Tirpitz would ultimately be attacked in Operation Catechism, where Lancasters dropped Tallboys on the battleship, sinking it and removing the main reason for the Highball’s development, as no remaining German surface vessels were deemed worthy of a specialised project to eliminate.
This wasn’t the end of the Highball project though, as 618 Squadron was deployed to Australia with the intent of using the Highball against Japanese Naval targets. The 27 Mosquitos were transported to Oz via Gibraltar and Ceylon aboard HMS Fencer and Striker, with the training taking place at RAAF Station Narrowmine, in New South Wales, with the unit becoming active in Feb of 1945. By this point in the war though, the Highball was deemed surplus to requirements, and No 618 was disbanded in July of 1945, marking the end to a promising, if totally unrealized operational capacity.
Aircraft Specification:
| Specifications: | ||
|---|---|---|
| Engine: | 2x Rolls-Royce Merlin 21 | |
| - | Take-off Power: 1.280 hp (954 kW) @ 3.000 RPM | |
| - | Combat Power: 1.490 hp (1.111 kW) @ 12.500 ft (3.810 m) | |
| Maximum Speed: | 380 mph (610 km/h) | |
| Crusing speed: | 265 mph (426 km/h) | |
| Service Ceiling: | 34.000 ft (10.000 m) | |
| Climb Rate: | 2.500 ft per min (12,7 m/s) | |
| Length: | 40 ft 9 ½in (12,43 m) | |
| Wing Span: | 54 ft 2 in (16,51 m) | |
| Height: | 15 ft 3 in (4,65 m) | |
| Empty Weight: | 13.400 lb (6.084 kg) | |
| Gross Weight: | 21.462 lb (9.744 kg) |
Armament:
- 2x Highball bouncing bomb
Additional Photos:
Sources:
- De Havilland Mosquito - Wikipedia (Wiki for mossies)
- The 'other' secret bouncing bomb of World War Two (Direct history of the highball modification)
- https://www.youtube.com/watch?v=sioR6aXEzUM&ab_channel=ArmouredArchivist (Video and history with heaps of footage)
- No. 618 Squadron RAF - Wikipedia (Squadron history)
- Mosquito Highball and other experimental versions | Secret Projects Forum (Heaps more photos and info)