Mass Properties

Here are some details from today's weight session in the old mirror coater room.

-  Used a calibrated load cell in line with the crane rigging to measure weight, and appropriate tare weights have been removed in the numbers presented here.
-  Measurements here are for a fully assembled instrument, including the support triangles, mounting plate, cal source, and eBox.  No cryos on board (wet instrument might be 10-15 lbs. heavier)


-  Installation weight, including SI Cart, weighed with all four wheels off the ground, is 1331 lbs.
-  Cart weight, all four wheels off the ground, is 368 lbs. (from the October measurement).
-  Weight of full-up SI, minus cart: 963 lbs.

-  Installation weight borne by the two forward wheels: 422 lbs. (211/wheel).
-  Installation weight borne by the two aft wheels:  914 lbs. (457/wheel).

-  Weight of full-up SI, minus cart, measured at forward ring: 365 lbs.
-  Weight of full-up SI, minus cart, measured at aft ring: 588.3 lbs.

(Single-end weight measurements do not exactly add to the four-wheel suspended numbers due to minor differences in the fulcrum points for each measurement which have not been accounted for.)

-  'Paper test' shows contact patches of 1.25 sq. in. at aft cart wheels, and 0.86 sq. in. at forward wheels.  This gives a mean contact pressure of 457/1.25 = 366 psi aft and 211/0.86 = 245 psi at the forward wheels.  No problem with the floor loading ICD :)

-  Counterweight rack, fully populated and with all cables in place weighs 317 lbs. (no waiver required!)