F-111B Conversion Part Two: Landing Gear

 A work in progress

The nose gear of the F-111B was very different but so was the main landing gear to a degree. As it happened, with two exceptions, the landing gear of the first three F-111Bs (BuNos 151970/71/72) was essentially identical to the landing gear on production F-111As, making the landing gear in the Hasegawa/Hobby 2000 kits usable as-is for them The two exceptions were that the nose gear on BuNo 151972  was damaged in the first of its two emergency landings and replaced with an F-111B nose-tow gear (at some point prior to its retirement, an F-111A nose landing gear was reinstalled) and the different aft main landing gear door on all seven F-111Bs.

BuNo 151972 with a nose-tow nose landing gear:

The aft main landing gear door was originally identical on the prototype F-111As and Bs. During extension and retraction it was articulated on two pairs of links so that on extension it swung down and back, remaining parallel to the bottom of the fuselage.

One pair of links was attached to pivot points on the main landing gear trunnion to which all its other parts were attached, one on either side of it, just below its pivot point on the back of the wheel well. The other pair were attached on the door just outboard of the first pair and to pivot points on each side of the wheel well. When the landing gear was extended or retracted, the door was driven by the first pair of links and remained parallel to the bottom of the fuselage when extended and retracted by the second pair of links (idlers).

Note that the trunnion on the 172 Hasegawa/Hobby 2000 kits is an open frame that should be covered with a thin piece of plastic.

A montage to illustrate the shape of the links and the location of the door: 

Apparently the rigging of the original aft main landing gear door was both finicky and subject to going out of adjustment, requiring a gear swing to remediate. As a result, early in F-111A production/operation, the door was simply mounted on the back side of the trunnion. This required that about six inches be removed from the back end of the door to clear the bottom of the fuselage when the landing gear was extended, so when it was retracted, there was a six inch wide opening on the bottom of the fuselage aft of the door.

This is the arrangement on all the F-111 kits except for the Revell, which has a simplified version of its original articulation. All seven of the F-111Bs flew with the original door, although in production it seems likely that it would have been mounted on the trunnion as well. While no aftermarket F-111B main landing gear tires are available, the F-111 kit tires can be narrowed and reduced in diameter accordingly.

All of the F-111Bs after the first three were delivered with the Navy landing gear. The F-111B main landing gear was the same as the F-111A’s and subsequent shore-based F-111s with the exception of the tires and the aft main landing gear door. At some point, to minimize a tipback problem in service, at least BuNo 152715 was modified to move the main landing gear wheels eight inches aft.

The Navy nose landing gear was completely different, however, except for the tire size. It was redesigned to add the nose-landing-gear tow and hold back for catapult launch as well as the Automatic Carrier Landing System radar corner-reflector. Both the strut and its actuation reflect the requirement that the nose landing gear react both the hold back and launch loads. Although no aftermarket F-111B nose landing gear is available, scratch building one is relatively easy.  Except for the wheels, the USAF nose gear isn't much use in that regard, though.

 Note that its shock strut angles forward (this is 151970 with the USAF nose gear) and ends well above the tire; the red markings on the nose wheel door were there to verify that the gear was fully extended:

 The Navy nose gear had a somewhat longer (the shock strut extended down to the axle) and beefier shock strut; the retraction actuator was also much beefier and attached above the shock strut piston:

 The Navy nose gear strut was mounted vertically (note the location of the wheel relative to the nose landing gear door):

 Ready to launch (the trail bar would hold the airplane back at full thrust and then release at the fitting to the strut when the catapult fired, remaining on the ship for reuse):

 The radar reflector was attached to the scissors so when the strut was extended in flight, it was raised to be vertical and above the right tire. Note the amber approach light, indicating to the LSO that the pilot is at the proper angle of attack.