When I went to work for Rockwell, in Downey, Calif. in 1973 ( before going up to Edwards for the Approach and Landing Test “ALT” program in 1974) the shuttle design had been pretty well hardened and the max gross weight for lift off was to be something like 168 K pounds, and it was stretched some, even then, to get that amount so as to accommodate a big 35K payload the Air Force needed to carry. Now, the orbiter  goes off at about 230K pounds.  These numbers are not precise, but the magnitude is about correct.   Yep, those jet engines would have been a pain in the “payload’.
Naturally, Fitz is correct about not being able to get the Orbiter off of their back during ferry flights. BUT, let me hum a few more  bars about attaching the orbiter to the 747:
 Re the nose strut: We had two different nose struts; one for the ferry flights and one for the ALT flights. The separation system consisted of  “ONE” explosive bolt on the ALT nose strut, with 3 explosive bolts at each of the main gear support locations, armed and ready to go on nearly all of the ALT flights as I remember it.  There were a couple of flights or so at the very beginning (as I recall) with no one in the Orbiter. In those cases  I doubt the explosive bolts were armed, in which case Fitz could not have gotten rid of the Orbiter if he wanted to. My thinking is that they would have had no idea, that early in the test, as to what a “dead” orbiter might do if released. Obviously in the ferry flight configuration there were no  explosive bolts on any of the struts, so you were/are stuck with the Orbiter up there for all ferry operations (no jettisoning capability).
 Also, (FYI) that ALT nose strut, could be adjusted by manually changing pin positions on it, to change the angle of incidence of the orbiter in relation to the the 747, as needed for a particular flight investigation (changed on the ground). Someone told me Fred Haise, the Orbiter astronaut,  had said they could adjust it in flight (electrically/hydraulically).  WRONG!  ( see photo of ALT strut).
 That”One” explosive  bolt on the ALT nose strut always bothered me, however, in that It was not a solid bolt. It was a hollow bolt, no larger than 2 inches in diameter, with only about 3/8 inch of actual metal (that would be the doughnut part of a doughnut), leaving about a 1 and ¼  inch diameter hole in the middle of it. That was all that was holding down the nose of the Orbiter in flight. If I had designed that bolt it would have been a solid 3 inches of metal and so strong it would likely never have been able to be blown apart.----- One of my many jobs, was sometimes being in the DFRC  control room and helping monitor oscilograph (sp?) readings, coming down from different parameters they were measuring during the flight.  One day I was monitoring the readings on that bolt and old Fitz was up there putting in rudder pulses and I sweating, as I saw the loads he was putting on that bolt (within limits, but right out there near them). I may be wrong, but I doubt that Fitz had ever actually looked at that bolt like I had, or he would not have been so cavalier, but then Fitz was Fitz; the world’s greatest test pilot.
 Also, probably not commonly known was the fact that on “MY” 747 they put in an escape system for the 747 flight crew, i.e. if you walked (or ran as the case may be) back out of the cockpit area a couple yards or so, there was a man hole size hole (with a lid over it, and railings as I recall) that you could open up in an emergency. This  hole was the entrance to really a big metal tube that went down and to the left and was affixed to the lower left side of the fuselage.  The emergency exit procedure for the flight crew was: get out of your  seat, go back and remove the cover over the hole, activate an pyro initiator that fired a shaped charge around the portion of the  fuselage that abutted the tube ( cutting a big hole in the side of  the 747), and JUMP IN THE METAL CHUTE ( making sure you had your parachute on---- yes, they had parachutes in the 747 on the ALT program). I do not know, of course, if they still have it set up that way for ferry flights in ‘MY “747” or not, but I would hope so. I have no knowledge of how the second carrier aircraft was/ is configured in this regard. Again, I would hope it is similar.
 NASA bought a second set of the attachment struts from Boeing, like you see in the  pictures. It was sort of lying around, up there in an old hangar at North Base, where all of our offices were; all during the program.------- Another job I was given, was to write the Deactivation plan for Rockwell activities, when the program was completed. So as part of the plan, I had to decide what to do with that second set of attachment equipment. I conferred with one other guy, about as knowledgeable as me, and we turned it over to salvage.  I have often imagined the hunt that must have gone on, looking for that second set of equipment, when they decided to fix up a second 747 carrier aircraft.

                            Right Main Strut

Edwards AFB /  Dryden Research Flight Facility (DFRC),  mate/demate device where the Orbiter is mated to the Carrier aircraft for it's return to Florida, when it lands at Edwards AFB today.         

Robert L. Mosley

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