World War II Database

Country of Origin	United Kingdom
Type	Rocket-Assisted Aerial Bomb
Length	5.030 m
Width	430.000 mm
Weight	2040.000 kg
Machinery	Nineteen 3-inch diameter rockets, bundled
Explosive Charge	230kg Shellite

Contributor: David Stubblebine

ww2dbaseThe Disney Bomb was rocket-assisted gravity bomb with a reinforced nose for penetrating hardened concrete structures. Officially designated as the "4500 lb CP/RA" (4500-pound Concrete Piercing/Rocket Assisted), it was most commonly known as the Disney Bomb (sometimes the Disney Swish).

The concept was for a conventional bomber to drop the bomb from an altitude of 20,000 feet. Thirty seconds after release, when the bomb was at about 5,000 feet, nineteen rocket motors in the bomb's tail section would fire for three seconds. This surge in speed was meant to increase the bomb's "punch" when it struck the target. The warhead contained 500 pounds of high explosive inside a slender, pointed, hardened steel casing that, with the added boost from the rockets, could theoretically pierce a thick reinforced concrete submarine pen or bunker.

The Disney Bomb was developed by a team headed by Royal Navy Captain Edward Terrell. The prevailing story is that Terrell got the idea for a rocket-assisted bomb from the animated 1943 feature film called "Victory Through Air Power" produced by the Walt Disney studios. In the film, there was a brief animation of a rocket-powered bomb diving through the roof of a reinforced submarine pen and exploding inside. It is thought that Disney's connection with this film is what gave the Disney Bomb its name.

Previous British large bomb designs, such as Tall Boy and Grand Slam, were designed as Earthquake Bombs that could still be effective when merely landing near their targets. The same design features that allowed these bombs to burrow into the ground also gave them some success against reinforced concrete targets, such as submarine pens. When used against such targets, Tall Boys and Grand Slams were meant to destroy the facilities themselves. The Disney Bomb, on the other hand, was intended to travel through the reinforced roof and then explode inside the structure, where it would hopefully destroy whatever was inside.

Disney Bomb prototype testing did not begin until very early 1945. Preliminary tests at bombing ranges in England were needed to understand how to aim the bombs, since their trajectories were very different from free-falling bombs. The recently captured rocket launching bunker at Watten, France was also used for testing both the accuracy of the bomb aiming and the effectiveness of the penetration. Post-war assessments of the Disney's characteristics established that the rocket boost gave the bombs a 26% increase in velocity, resulting in a 60% increase in the energy imparted on impact.

Although conceived by British Naval designers, the bombs were not fitted to British bombers. Some sources speculate this was due to inter-service rivalry but it is perhaps more likely that the bomb's need for precise aiming meant the Americans' experience with daylight precision bombing made the United States Army Air Forces the logical choice. Either way, the USAAF was enlisted to test and deploy the weapons. The bomb's design required a long and slender shape that made them too long for the bomb bays of the B-17 Fortresses, so bomb racks were fitted under the wings of certain bombers. The first operational use of the Disney Bombs was on 10 Feb 1945 against the reinforced Schnellboot pens at IJmuiden, Netherlands. Disney Bombs were only used in a total of five attacks on German targets and a total of 158 bombs were expended. The other four raids, ending on 4 Apr 1945, included two more attacks on the Schnellboot pens at IJmuiden, bombing the reinforced U-Boat yard at Hamburg, Germany, and on the reinforced U-Boat yard at Farge near Bremen, Germany. All of these targets had also been bombed on several other occasions with Tall Boy and Grand Slam bombs, as well as large quantities of conventional bombs. Many of the targets the Disney Bomb was created for, like the submarine pens along the French coast, had already been captured by Allied forces before the Disney Bomb was completed, making it unnecessary to bomb them from the air.

Other factors brought the war in Europe to an end. The Disney Bomb was not deployed in the Pacific so the weapon's combat career was over. However, the American and British frustration with the stubborn reinforced concrete buildings used by the Germans led to a brief afterlife for several of the "bunker buster" bombs. The USAAF and the RAF engaged in the joint Project Ruby to more fully determine the effectiveness of six of the "bunker buster" weapons, including the Disney Bomb. The same German reinforced structures served as testing targets for Project Ruby, although many of the bombs dropped were inert and were dropped mainly to evaluate their penetration qualities. The one German facility that Ruby bombed heavily with a variety of live bombs were the submarine pens on the island of Heligoland in the North Sea, since the island had been evacuated during the war and was not repopulated until after Operation Ruby had closed. The purpose behind Project Ruby was not only to work out how to better disable hardened targets like those the Germans had built, but also to evaluate how to construct better hardened targets of their own.

The biggest impediment with all of these weapon systems, however, was their accuracy, or lack thereof. These were all unguided, high altitude, free-fall weapons needed to hit a reasonably precise aiming point. On that basis, the concept was nearly unachievable from the start. It was not until the introduction of guided munitions that came much later that lessons learned in Operation Ruby about bomb construction could be applied more usefully.

In 2009, an unexploded warhead from a Disney Bomb was extracted from the heavily reinforced roof of the Watten Bunker near Watten, France after over 60 years. This was probably from a post-war test but it was still noteworthy in that the warhead's hardened steel nose was not the slightest bit deformed by the impact that burrowed the bomb nine feet into the reinforced concrete and, even without exploding, the impact alone evacuated a large crater.

Sources:
United States Army Air Forces/United States Air Force
Donald A. Neill – Diehard Empiricist (17 Mar 2012)
Britain at War Magazine
Secret Projects Blog
The Northern Historian (YouTube) – "The Concrete Piercing - Bunker Busting - Rocket Powered Bomb"
Le Blockhaus d'Eperlecques
Wikipedia ww2dbase

Last Major Revision: Oct 2023

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Disney Timeline

3 Feb 1945	USAAF B-17 Fortress bombers dropped Disney Bombs on the recently captured Watten Bunker near Watten, France as a test of the new bomb design.
10 Feb 1945	Nine B-17 Fortresses of the 92nd Bomb Group flying from RAF Podington in Bedfordshire carried out the first operational attack with Disney rocket-assisted bombs on the E-Boat pens at IJmuiden, Netherlands.
14 Mar 1945	Nine B-17 Fortresses of the 92nd Bomb Group flying from RAF Podington in Bedfordshire dropped Disney rocket-assisted bombs on the E-Boat pens at IJmuiden, Netherlands.
21 Mar 1945	In a Disney operation, three B-17 Fortresses attacked the E-boat pens at IJmuiden, Netherlands with rocket-assisted bombs.
30 Mar 1945	The USAAF 306th Bomb Group flying from RAF Thurleigh launched twelve B-17 Fortress bombers against a submarine yard within a reinforced concrete structure at Farge near Bremen, Germany. This was the 306th's first use of the Disney Bomb. Twenty B-17s from another Eighth Air Force bomb group also bombed Farge with Disney Bombs. A total of 14 bobmers were damaged on this mission.
4 Apr 1945	Twenty-two B-17 Fortresses flew a Disney mission attacking the Finkenwarder U-boat yard at Hamburg, Germany.
27 Jan 2009	An unexploded warhead from a Disney Bomb was extracted from the reinforced concrete roof of the Watten V2 rocket launching bunker in Watten, France, over 60 years after it was dropped.

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