The Navy was unhappy with the F-111B's tip-back angle. In other words, the main landing gear was too close to the airplane's center of gravity with the wings swept back, so if the brakes were applied while the airplane was being pushed back into a parking spot, the momentum would cause the airplane to tip back. This might also result from the roll of the carrier. And there were dire consequences: it might result in the airplane and brake rider being lost over the side if the tail skid was past the deck edge.
One early solution was a moment-carrying tow bar to move the cg forward. It was evaluated but determined to be inadequate, not to mention awkward to handle.
The decision for F-111B production was to move the wheels eight-inches farther aft.
I had noted that F-111B landing gear installation had changed at some point early on (probably with 151973 but certainly with 974 and 152714/5) to move the wheels aft.
(Note that 972 has the early Air Force tires while 715 has the Navy tires. Also see
http://tailspintopics.blogspot.com/2009/10/grumman-f-111b.html)
The landing gear was definitely rotated more around the retraction pivot point, moving the wheels aft. However, a rough layout indicated that the shift aft was almost certainly less than eight inches.
Steven Hyre recently posted some F-111B illustrations on his Facebook page, The F-111 Historical Association, that were new to me. One of them was for ECP 1000 and revealed the planned change:
On close inspection of the dashed lines, you'll see that the landing-gear crossbeam has been redesigned to move the axle aft by eight inches. Like the raised cockpit, this was a production change that was not present on 152714 or 715.
You are doing a fantastic job of nailing down all the detail changes Tommy. How long before a Second Enlarged edition of the F-111B book? Please keep up the fantastic work you're doing.
ReplyDeleteNicholas - thanks for the compliment. Steve Ginter is just about sold out and I only have a few left. He doesn't think that there would be enough demand to justify the investment in a second edition. I'm open to suggestions as to how to update it myself.
ReplyDeleteI raised this at my model club meeting this evening. Keeping your comments in mind the consensus is that offering an errata/addendum as a PDF would work. Payment by PayPal. Looking over my saved copies of your blog pages I think you've already done most of the work. If you can get an agreement with the F-111 Historical Association I think it would be pretty close to complete.
ReplyDeleteThanks for the thought. At the moment, I've decided not to do an update unless I can get a copy of the at-sea trials aboard Coral Sea. That's the one big hole left in my file of reference material.
Delete972 was my aircraft T lakehurst used for jet blast testing never could get to 4 or 5 afterburner compressor stalled every time Harry conover bertram31@optonline.net
ReplyDelete