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"NASA conducted five manned spaceflight programs: Mercury, Gemini, Apollo, Skylab, and Shuttle. The latter four programs produced spacecraft that had on-board digital computers"

Wow, how did they launch something to the orbit without any computer on-board? Was it just like a "dumb slingshot projectile"?

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> Wow, how did they launch something to the orbit without any computer on-board? Was it just like a "dumb slingshot projectile"?

There was no on-board digital computer but there was quite sophisticated electronic circuitry for the era on board the Mercury spacecraft and the various launch vehicles that were used with it.

The guidance systems used mechanical gyroscopes wired to analog PID controllers built from vacuum tubes in early rockets and later from transistors and opamps.

There isn't a lot of control that you put into a space launch. After the initial subsonic pitchover maneuver, the spacecraft is just kept pointing nose to the direction of the travel. Any attempt to change the attitude of the space craft by turning it would cause the aerodynamic stress to tear the vehicle to shreds. Diverging from the nominal trajectory will start an abort or self destruct procedure. Errors accumulated from the launch will be corrected by the 2nd (or 3rd) stage (or the Mercury spacecraft in this case) using radar measurements from the surface.

"Project Mercury was America's first man-in-space effort. The McDonnell-Douglas Corporation developed the Mercury spacecraft in the familiar bell shape. It was barely large enough for its single occupant and had no independent maneuvering capability save attitude control jets. Its orbital path was completely dependent on the accuracy of the guidance of the Atlas booster rocket. Re-entry was calculated by a realtime computing center on the ground, with retrofire times and firing attitude transmitted to the spacecraft while in flight. Therefore, it was unnecessary for the Mercury spacecraft to have a computer, as all functions required for its limited flight objectives were handled by other systems."

http://history.nasa.gov/computers/ch1-1.html

Perhaps they used "analog computers"? One example: http://en.wikipedia.org/wiki/ELWAT

Not so much. For Mercury, they used two IBM 7090's on a ground station. So the majority of calculations was done on the ground, with the vessel sending telemetry data.