Heavy Lifting

June 14, 2011
'Facts' don't add up.
Re: "The Saturn V Rocket and Supply Chain Innovation," May 2011

Andrew R. Thomas notes that the Saturn V "weighed 6.3 million pounds, about the weight of... 50 Boeing 747s."

Not so much. The latest 747-8 aircraft have a maximum certificated take-off weight (MTOW) of 975,000 pounds, so the Saturn V was only as heavy as six or seven 747s, not 50. Don't know how you did the math on that. Even the earliest /100 747s had a MTOW of 833,000 pounds.

Later in your article you state that the Saturn V had a takeoff thrust of 7.7 million pounds, and "getting a jumbo jet into the air requires a mere 66,500 pounds of thrust."

Again, not so much. The 66,500 number you mention is correct for the 747/8 engine, but there are four of these hanging on each aircraft, for a total of 266,000 pounds available thrust at takeoff. If you tried to accelerate an aircraft that weighs 975,000 pounds with just 66,000 pounds of thrust, ignoring all friction and drag losses you'd get only .07 gs acceleration, or 2.2 ft/s^2. At that acceleration, ignoring all friction and drag, it would take over 100 seconds to get to a 140-knot takeoff speed, and the runway would then need to be over 12,000 feet long just to get to the takeoff point.

You might want to get a fact checker to read your articles before you send them off, just to see if they pass the "giggle test."

Jerry LeCroy, P.E.
Boeing Advanced Programs

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