2 September 2023: Added an illustration of how the nose gear shock strut functioned.
7 June 2024: Added Mk 7 and Mk 8 Control Panels
This post incorporates material provided from the Greater St. Louis Air and Space Museum by Mark Nankivil.
Click HERE for my previous post on the "Nuclear Banshees". When I get a chance, I'll correct some of the discrepancies in it. Click HERE for my F2H Banshee Modeler's Notes: it includes links to several of my other posts on the Banshee.
By the early 1950s, the Mk 7 and Mk 8, tactical nuclear weapons small enough to be carried by single-seat fighters and bombers, had been developed. The U.S. Navy quickly modified two carrier-based airplanes to accommodate them, the Douglas AD Skyraider (see http://tailspintopics.blogspot.com/2022/04/ad-4-skyraider-variant-ad-4b.html) and the McDonnell F2H Banshee. The suffix B was added to the designation of these airplanes to identify them as having non-standard armament.
The Mk 7 was lighter (about 1,680 lbs) than the Mk 8 (about 3,250 lbs) but much larger (30.5 inches in diameter and 182 inches long). To fit it under the inboard wing of the F2H-2 required that the landing gear shock struts be pressurized to extend them to their full travel.
The nose landing gear extension;
With the help of Jerry Wells, I was finally able to establish how the nose landing gear shock strut extended:
The extension required the addition of small hydraulic reservoirs to add fluid to and remove fluid from the shock struts as required:
The result increased the height of the requisite pylon above the ground by 10 inches, providing just enough clearance for a carrier launch with a Mk 7:
Note that the tail cone had to be installed "upside down" to provide clearance from the underside of the wing. This also meant that the retracted tail fin could not be extended before the bomb was dropped, so the electric motor that did that was replaced by first one and then two springs; the fin was held in the retracted position by a locking device until the bomb was dropped and a lanyard attached to the pylon opened it.
An elaborate arrangement of sway braces and a spring-activated separation device on the inboard aft end of the bomb was required to carry and safely separate the bomb from the Banshee when it was dropped.
Loading the Mk 8 did not require extending the shock structs but did require that the left inboard flap extension be disabled.
(For a dimensioned drawing of the Mk 8, see the AD-4 link above.)
It necessitated a different pylon/shackle (30-inch distance between lugs for one thing), arrangement of sway braces, and a simpler separation feature.
The left inboard flap had to be locked up for clearance with the Mk 8 tail fin:
The pylon location, on the same wing station as the original inboard stores pylon, was the same for both bombs; a notch in the center section flaps was provided for Mk 7 clearance (not shown is the recess on the outboard center section flap for the Mk 8 fin clearance noted above).
It was essentially coincident with the outboard edge of the engine intake opening:
Note that this initial capability predated the development of the Low Altitude Bomb System (LABS) delivery (click HERE). Instead, the bomb was to be dropped from altitude, in this example in a dive utilizing a "loft" bomb deliver capability, not to be confused with the loft options provided by LABS,
The flight manual advised caution not to exceed G limits when the Mk 7 was released in the loft maneuver; use of loft delivery for the much heavier Mk 8 was prohibited.
A couple of details on the Mk 7 development:
Problems with its stability and trajectory were discovered during initial test drops. This was solved in part by adding wedges one one side of the tips of the tail fins that resulted in the bomb spiraling like a football.
Another was the initial use of barometric pressure to provide an air-burst capability for more wide-spread devastation. However, as the Mk 7 neared the ground, it was going faster than the measurement of the air pressure could keep up with from a detonation accuracy standpoint. As a result, speed brakes were initially provided between the tail fins that opened up when the bomb was dropped (it probably also provide a few vital seconds for the pilot to get far enough away to avoid getting "hoist by his own petard").
The addition of radar sensing of the height above ground resulted in them being deleted from the Mk 7.
Note that the Mk 8 did not have speed brakes because its raison d'etre was destruction of well-protected submarine shelters, accomplished by not detonating until as far below ground as possible, which meant that the faster it was going when it hit the ground, the better.
The development of bespoke pylons (to be described in a subsequent post
covering the F2H-3/4 nuclear-strike configuration) and more options for changing the angle of the tail cone allowed the Mk 7 to
be loaded with the fins pointed upwards and eliminated the separate sway
braces required for the Mks 7 and 8.
An important feature of the F2H-2B was the addition of the newly developed inflight refueling capability. This was accomplished by adding a fuel probe replacing one of the 20mm cannons on the right side of the fuselage.
Only the fuselage fuel tanks could be refilled in flight, probably because these early jets did not have single-point refueling capability. Also filling the tip tanks would have required the addition of additional fuel lines and flow management valves and controls. That was a tradeoff against the extra range that would be achieved, particularly since even though the store was mounted fairly close to the center line, the tip tank on that side could only be partially filled before takeoff since only so much lateral imbalance could be offset by the roll-control power (i.e. aileron effectiveness) available at low speeds. At cruise speeds, however, the imbalance could probably be accommodated, albeit at some increase in drag due to the control-surface deflection.
The early refueling probe had a tip that resembled a baby bottle nipple. It was subsequently replaced by the one that's now standard across U.S. and NATO probes.
There is currently a discrepancy in the number of F2H-2Bs. In my earlier post on Nuclear Banshees (see link above including comments) there were 25 to as many as 31, depending on the source. The effectivity given in the 15 January 1954 document provided by Mark Nankivil lists 60!:
125030-70
125500-05
125650-62
In any event, the F2H-2Bs were deployed in both "composite" squadron detachments and fighter squadrons:
This squadron's markings in color and regrettably, a bit out of focus:
The management of the store (arming, etc) was provided by a panel mounted on the right side of the cockpit above the console. Which panel was used depended on whether a Mk 7 or Mk 8 being carried.
Mk 7
Mk 8
