Slide rule use in space

[4ster]

(05-06-2016 04:03 PM)Accutron Wrote:  

(05-06-2016 01:59 PM)4ster Wrote:  my very smart, slightly older, civil engineering friend snorted and said there was no way a slide had the precision necessary to navigate a space craft.

I guess that's why NASA hires aeronautical engineers for such things instead of civil engineers. The early space program was built with slide rules. Here's a quote from NASA engineer Bob Bobola:

"Computers were around, but they were great big in size. Most reports were handwritten, and a lot of the calculations – weight, center of gravity – were mostly done by hand using a slide rule. It's a wonder we were successful."

Faith 7 (Mercury-Atlas 9) lost altitude readings on the 20th orbit, and lost power to the automatic stabilization and control system on the 21st orbit. Gordon Cooper had to manually calculate everything with a Bulova Accutron Astronaut 214 wristwatch and a circa 1949 Keuffel & Esser slide rule, and pilot the capsule manually. It was the most accurate splashdown in the whole Mercury program, landing about four miles from the recovery ship.

I'll relay your observation about NASA's engineering preference to my civil engineering friend, which reminds me of a joke proving that God is a civil engineer...but I digress.

I looked into the Faith 7 flight, a truly inspiring story of a great pilot overcoming his craft's system failures, thanks for relating the incident. I'm not sure it proves my supposition about navigation using slide rules since ground support supplied the timing of the re-entry burn. I would assume that Cooper double checked the NASA math with his slide rule but from what I read the start of the burn was relayed via radio by Glen.

From the NASA history site:
Twenty-three minutes later Cooper came into contact with Glenn again, reporting himself in retroattitude, holding manually, and with checkoff list complete. Glenn gave the 10-second countdown, and Cooper, keeping his pitch down 34 degrees by his window reticle, shot his retrorockets manually on the "Mark!" Glenn reported: "Right on the old gazoo. . . . Dealer's choice on reentry here, [501] fly-by-wire or manual . . . It's been a real fine flight, Gordon. Real beautiful all the way. Have a cool reentry, will you."

Cooper timed his burn with his watch.

Except for re-entry and time spent on the far side of the moon, NASA was almost always in contact with their spacecraft. NASA probably generated all navigation data and relayed it to the spacecraft via radio on the Mercury missions. Which to me implies that the heavy lifting would have been done by computer. I did find that the Gemini space craft were the first with a "solid state computer" on board.