Questions tagged [unit-systems]

Questions that involve the choice of a system of units for measurement or calculations. For example, metric, U.S. customary, or Imperial units.

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3
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0answers
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Are there examples of errors caused by the use of two English units?

The Mars Climate Orbiter was infamously lost because of software which used metric units in some places and U.S. Customary units in other places, without conversion factors. The incident is discussed ...
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3answers
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How is foot-pounds of energy defined?

Tom Lodgson's classic textbook Orbital Mechanics: Theory and Applications frequently measures energy in foot-pounds, which I'd always thought to measure torque. The book doesn't define it. Is it the ...
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2answers
502 views

Why was the LRV's speed gauge displaying metric units?

In the question Why did NASA use U.S customary units? it was basically stated in the answers that even when metric units were used "internally" (e.g. the AGC), the units presented to the astronauts ...
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Was Arthur J. Schwaniger one of very few US born NASA scientists using metric units?

Free-return trajectories were studied by Arthur Schwaniger of NASA in 1963 with reference to the Earth–Moon system. Those trajectories were used for the first Apollo missions. Mr. Schwaniger, who ...
7
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1answer
359 views

Which unit system was used by german rocket scientists at NASA for calculations?

There were numerous german rocket scientists at NASA, see wikipedia 1, 2. They were used to the metric system which they used when working for the V-2 at Penemünde. But what unit system did they use ...
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3answers
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Why did NASA use U.S customary units?

NASA was using U.S customary units (inches, feet, nautical miles, pounds, tons, US gallons etc.) during the Mercury and Apollo programmes, and beyond. There are significant disadvantages to using U.S ...
4
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1answer
215 views

What set of units does the Orion capsule cockpit instrumention use?

Shuttle was English, ISS is metric. What's Orion? For example: What units are inertial velocity displayed in?
4
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1answer
375 views

Martian Names for the Year and Month Time Units

A Martian day unit is called a Sol. A week is supposedly still 7 days/sols. Have there been any (real or fictional) suggestions for new names for other time units like the Martian year? How about ...
36
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4answers
6k views

Why wasn't the Mars Climate Orbiter's fatal error caught prior to launch?

The Mars Climate Orbiter failed in 1999 due to: ground-based computer software which produced output in non-SI units of pound (force)-seconds (lbf·s) instead of the SI units of newton-seconds (N·s) ...
27
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1answer
4k views

ISS nuts and bolts; Metric, SAE or both?

The International Space Station (ISS) is a joint construction of many countries around the world. Most of whom use the metric system for measuring including sizing of bolts, nuts and fasteners. ...
13
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1answer
6k views

Did NASA use metric units for the Mercury missions?

Did NASA use metric or English units for Project Mercury? For example, did they measure delta-v in meters/second or in feet/second?