For Safe Landings On Two Planets
The 2013 National Air and Space Museum Trophy Winners.
- By The Editors
- Air & Space magazine, April 2013
NASA / JPL-CalTech
(Page 3 of 5)
That’s something that the team flying in 2020 is going to look long and hard at, whether to put on a third antenna. For the layperson, the Sky Crane will look identical, but there will be some subtle changes the team will make to strengthen its reliability.
In his 2006 book 747, written with aerospace historian Jay Spenser, Joe Sutter recalls the struggles, company politics, and flashes of genius that characterized the design of what was then the world’s largest airliner. In this excerpt, he describes a crisis he faced late in the design process.
Like all airplanes in development, the 747 gained weight during its design. In April 1966, when the contract with Pan Am launched the 747 program, the airplane’s projected gross weight was 655,000 pounds. A year later, it had risen to 680,000 pounds and was still climbing.
This weight growth threatened the entire program. A heavier airplane meant Pan Am and other customers wouldn’t be able to carry as much revenue-generating payload. Juan Trippe [the leader of Pan American Airways] was personally monitoring the progress of the 747. Concerned about its weight growth, he spoke directly with [Boeing president] Bill Allen. It was agreed that Trippe, his assistant Sanford Kauffman, chief engineer John Borger, and other Pan Am officials would come out to Seattle so that I could brief them on this issue.
Pulling no punches, I told Trippe to his face that this weight growth wasn’t just a Boeing problem. In front of Bill Allen and the others, I pointed out that more than half the excess weight was the direct result of ongoing changes specified by Pan Am, which had added to the equipment and amenities they wanted aboard the airplane. The upgrades they had specified for the 747’s seating, passenger lounges, lavatories, galleys, cargo systems, and so on made sense, but every bit of it added weight. “It’s just as much your problem as ours,” I concluded.
Juan Trippe obviously didn’t like what he’d heard but he reserved comment. Nobody else was happy with me either as that meeting ended, but on the basis of that key meeting we redefined the 747’s takeoff weight from 680,000 to 710,000 pounds, which was clearly the right thing to do. If we hadn’t taken that painful step in agreement with Pan Am, the airplane would not have met its mission goals.
Airplane design is the ultimate exercise in compromise. If you increase the fuel load, for example, you need a stronger, roomier structure to house it, so airplane weight and drag go up. You also need more powerful engines to lift it all, which means higher fuel consumption. The design team’s job is therefore to define the optimal balance between these elements that yields the best results. The exception is safety, which is never the subject of compromise. Then as now, my guiding belief is that you’re not living up to the faith placed in you if you don’t play things the way you see them. When you’re in a position of responsibility, you need to do what’s right. In the aerospace arena, if you don’t have the courage to face up to difficult situations—and that includes making sure that unwelcome truths are heard and acted on—then you have no business being a chief engineer.
Weight was now the issue that woke me up at night in a cold sweat. The numbers were coming in very, very high. Worse still, we didn’t know precisely where we stood. Our evolving design was so different in scale from anything the industry had built before that we couldn’t estimate its weight with any certainty.