XF-87 Blackhawk

Development of the XF-87 began at Curtiss-Wright in 1946, it would eventually be intended to be an all-weather interceptor. The Blackhawk was developed from an earlier ground attack, tactical bomber design, the XA-43. The Blackhawk was a response to the initial specification for a jet-powered night fighter, capable of speeds up to 530 mph, issued by the US Army Air Force in August 1945.

A number of companies responded including Bell Aircraft, Consolidated-Vultee, Douglas Aircraft, Northrop, Goodyear and Curtiss-Wright. The US Army Air Force down-selected Northrop’s design – then known as the N-24 and the Curtiss-Wright design- known as the Model 29A.

Curtiss-Wright XF-87 (US Air Force)

The XP-87 had a two-man crew seated side-by-side and was powered by two pairs of Westinghouse XJ34-WE-7 turbojet engines mounted on the wings. In comparison to the sleeker Northrop design, the Blackhawk was a slightly larger, bulkier and heavier aircraft with a straight wing profile. The XJ34-WE-7 turbojets only provided 12,000 lbf and Curtiss-Wright’s test pilot B. Lee Miller described performance in initial tests as sluggish. The Blackhawk’s armament was to consist of four 20mm cannons mounted in a nose turret.

The US Army Air Force designated the Curtiss-Wright jet the XP-87, while Northrop’s N-24 became the XP-89 and full-scale models of both were ordered.

The Curtis XP-87 (Curtiss-Wright, courtesy of Mark Lane)

In June 1948 the newly formed US Air Force re-designated fighters from P to F and the XP-87 became the XF-87 when prototypes were ordered. The XF-87 made its first flight in March 1948. During subsequent flight evaluations in October 1948, the Northrop XF-89 was found to be faster than the XF-87 and the US Navy’s XF3D (Douglas F3D Skyknight). While the Blackhawk was a capable and generally satisfactory aircraft it was deemed to be underpowered. It also reportedly suffered from buffeting at relatively slow speeds.

Walter Tydon’s patent for the Blackhawk’s landing gear (US Patent Office)

Evaluators disliked the Northrop and reportedly favoured the XF-87, however, one evaluating pilot likened its handling to a medium Bomber. An improved faster and more powerful Blackhawk was planned with J47 engines from General Electric. The fate of a second prototype is unclear and sources conflict. Most sources state that the XF-87 never had its armament fitted, however, photographic evidence clearly shows an aircraft, not with a turret, but with four nose mounted guns. This aircraft may be one of the airworthy prototypes or it could be a full-scale mock up built to show the USAAF during the selection process.

Despite the trials favouring the XF-89, the USAF initially ordered 57 F-87A fighters and 30 RF-87A reconnaissance aircraft from Curtiss-Wright in June 1948. Curtis-Wright and the USAF began a publicity campaign to unveil the new fighter, even appearing on the cover of an August edition of Aviation Week and in numerous other aviation publications, but the orders were abruptly cancelled in October 1948 and the USAF moved forward the development of the Northrop XF-89 instead. Check out our video on the F-89 Scorpion linked above.

The ‘F-87’ Blackhawk on the cover of Aviation Week (courtesy of Mark Lane)

The reason for this reversal of the decision is unclear. Only minor faults had been identified during testing and the more powerful J47 engines would have greatly increased the Blackhawk’s speed. The official reason for the cancellation was reportedly a disagreement on the price of a redesigned wing profile. According to his memoir, Walter Tydon, Curtiss-Wright’s chief engineer at the time, believed that some bad blood between Curtiss-Wright’s management and the then-President Harry S. Truman may have led the F-87 contract to be cancelled. Truman was Senator for Missouri from 1935 to 1945 and during that time Tydon believed he had come into conflict with the Curtiss-Wright’s management, perhaps regarding the company’s factory in St. Louis. Without substantial archival research it is difficult to verify either the official reason or Tydon’s theory.

Another potential reason for the cancellation was raised during the Congressional Hearings regarding the B-36 Program, Congressman Charles B. Deane noted that both Curtiss-Wright and Northrop had been informed that “unless they agreed to merge with Consolidated Vultee, business would be bad for them.” The testimony before the hearing notes that Curtiss-Wright were unenthusiastic about a potential merger and this might have been why the F-87 contract was cancelled. The Secretary of the Air Force denied this, however, stating that the cancellation was the result of “operating difficulties with the experimental model of the F-87, plus increasingly satisfactory operating data on competitive all-weather fighters.”

The XF-87 Blackhawk taking off (courtesy of Mark Lane)

Sadly, the prototype XF-87 Blackhawk’s was reportedly scrapped and photographs and footage of the initial flight testing of the Blackhawk is all we have left. The loss of the interceptor contract to Northrop led to the end of Curtiss-Wright’s aircraft production, with the Blackhawk being their last fighter design.

Special thanks to Mark Lane, the grandson of Walter Tydon, Curtiss-Wright’s chief engineer, for taking the time to discuss the Blackhawk and his grandfather’s role in its design.


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Bibliography:

Saga of the P-40 and Curtiss Airplane Division: Its Rise and Demise, W. Tydon

Newest Fighter In the Skies, Aviation Week, 2 Aug. 1948

Ad featured in Army & Navy Journal, Vol. 85, No. 40, 7 Aug. 1948 (source)

Ad featured in Air Force, Vo.31, No.9, Sept. 1948 (source)

‘Investigation of the B-36 Bomber Program’, US Congressional Hearing, Aug.-Oct. 1949, (source)

Curtiss Aircraft, 1907-1947, P.M. Bowers (1987)

American Attack Aircraft Since 1926, E.R. Johnson (2008)

The Big Book of X-Bombers & X-Fighters: USAF Jet-Powered Experimental Aircraft and Their Propulsive Systems, S. Pace (2016)

Curtiss-Wright Aeroplane Factory, Missouri, National Register of Historic Places, US National Park Service (2016) (source)

The Battle of Palmdale – WW2 Drone Hellcat vs F-89 Scorpion Jet Interceptors

The Battle of Palmdale is one of those historic events that could easily spawn clickbait titles: US Navy vs US Air Force, Drone vs Manned Fighter, Runaway WW2 fighter vs Rocket-armed Jet Interceptor. None of these would be a lie! 

Artists impression of the ‘battle’ (Pageant magazine, 1957)

On 16th August, 1956 a US Navy Grumman F6F-5K Hellcat a target drone went rouge over California and the USAF scrambled a pair of Northrop F-89 Scorpions to shoot it down. The F-89s failed to down the Hellcat but did manage to start a serious wildfire. 

Check out the video below:


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The B53 ‘Bunker Busting’ Thermonuclear Bomb

In the late 1950s the US military began development of a bomb capable of destroying deeply buried bunkers. The result was a bunker busting unguided thermonuclear bomb. Durng a visit to the Atomic Testing Museum, in Las Vegas, Matt had the chance to take a look at a decommissioned B53 up close.

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B53 on display at the Atomic Testing Museum (Matthew Moss)

The B53 is a two-stage high-yield thermonuclear weapon, designed as a bunker buster, that could deliver a massive shockwave deep underground to the deepest Soviet command and control bunkers. Developed between 1958 and 1961, the B53 was intended to combat deeply emplaced Soviet bunkers with a yield of 9 megatons. It used a highly enriched uranium core as its primary fission stage with Lithium-6 deuteride as its second stage fusion element. The warhead itself was developed from the earlier Mk46 warhead, the experimental TX-53 was tested at the Pacific Proving Grounds as part of Operation HARDTACK I, which saw no less than 35 nuclear test detonations. Codenamed HARDTAK OAK, the TX-53 was detonated aboard a floating barge on 28th June 1958, with a yield of 8.9 megatons. The detonation created a cloud 78,000 feet (23.8 km) tall.

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Cloud produced by HARDTACK OAK (Los Alamos National Laboratory Archive)

Designed to be dropped from the Strategic Air Command’s B-47, B-52 or B-58 bombers, the B53 is a gravity bomb which free fell to its target and could be air or surface detonated. The bomb itself weighed 8850 lbs or 4014kg and the casing is 12.5 feet long (3.8m) and just about 50in (1.27m) in diameter. The bomb’s outer-casing is split into a nose section, a two-piece central casing and the rear assembly with four fins which housed the parachute assembly. They were built by the Atomic Energy Commission between 1962 and 1965, over 340 bombs were built. Initially designated the Mk53 it was re-designated the B53 in 1968, when the US Air Force updated its ordnance nomenclature.

The bomb itself could be deployed in four ways: a delayed surface burst, a free fall air burst, a parachute retarded air burst (the B53 had five parachutes at the rear which can be deployed) or an immediate contact surface burst. Here we can see the panel to control the parachute deployment, with markings for safe, free fall and retard.

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Declassified general diagram showing the assemblies of the B53 (US DoD)

The B53 was obsolete in terms of its safety by the early 1980s with none of the more modern safety features such as an Enhanced Nuclear Detonation Safety (ENDS) additionally its explosive lens, consisting of a mix of RDX and TNT was not an insensitive munition – meaning it wasn’t designed to resist detonation from external stimuli or damage. The B53 also had no Fire-Resistant Pit (which prevents the spread of radioactive material in the event of a far), Permissive Action Link (which prevent unauthorised arming) or Command Disable safety measures.

B53 at the Pantex Plant in Texas about to begin the dismantling process (National Nuclear Security Administration)

Many of the B53s in US inventory were decommissioned in the mid-1980s, and by 1987 just 50 were retained in inventory. The last of these were disassembled and decommissioned by October 2011 – after being in service for 50 years. The B53 was replaced in its bunker busting role by the smaller B61 Mod 11.


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Bibliography:

Operation Hardtack I Fact Sheet, US Strategic Command Centre for Combating Weapons of Mass Destruction, (source)

Operation Hardtack I 1958, US Defense Nuclear Agency, (source)

‘Scrapping the Unsafe Nuke’, Federation of American Scientists, (source)

Hardtack OAK footage courtesy of Atomicarchive