View Full Version : Imperial or Metric measurements for US rockets

2014-Mar-22, 05:01 PM
When did the Americans change over from using imperial to metric measurements for building their rockets?

Was the Shuttle originally designed in imperial?

Is there any practical easement for a rocket metal-worker creating from a draft plan a screw measured as 3/32" or measured as 2.38mm?

2014-Mar-22, 05:33 PM
Don't know most of your answers but you say 3/32 screw, so that's an opening for threads. There are many systems of threads, one of the most international is pipe threads, the original bsp system still in use most places, in USA as npt . For bolts the metric system was mostly reinvented although M6 is close to 0BA at 1 mm pitch, different thread angles. There is both metric fine and coarse series, for most jobs and none is the same as previous threads. Plus there are special threads such as self tapping,( why do extrusions always use the strange M3.5?). most old threads hang on because of spares so you can still get whit worth bolts etc. unf, unc, bsf, . And there's the head forms.......

2014-Mar-22, 08:10 PM
The Soviets managed with great effort to reverse engineer near exact copies from captured imperial-designed US B-29s, but in metric!


The Soviet Union used the metric system, thus sheet aluminum in thicknesses matching the B-29's imperial measurements were unavailable. The corresponding metric-gauge metal was of different thicknesses. Alloys and other materials new to the Soviet Union had to be brought into production. Extensive re-engineering had to take place to compensate for the differences, and Soviet official strength margins had to be decreased to avoid further redesign, yet despite these challenges the prototype Tu-4 only weighed about 750 lb more than the B-29, a difference of less than 1%

2014-Mar-24, 02:47 AM
Seems that NASA does indeed still use imperial measurements to this day