JF Mezei wrote on Mon, 20 Aug 2018
23:43:50 -0400:

On 2018-08-20 23:31, Fred J. McCall wrote:

I assume so. Dragon V2 is supposed to be able to carry cargo rather
than people and I would think just removing seats and such to switch
to a cargo configuration wouldn't invalidate any 'test' flights for
man rating of Falcon 9/Dragon V2 system configuration.

Won't a cargo variant of Dragon 2 fly first, and test the docking
software and hardware (it goes to a PMA, right, instead of CBM ?)


I don't recall them saying that first test would be with a cargo
variant, but it certainly could be.


In terms of the crewed version, wouldn't NASA want to put instrumented
dummies in there to record G forces, vibration, noise and atmosphere
pressure etc? (especially for the landing).


Unnecessary. Any dummies will get the same g forces as the rest of
the capsule. Even if the capsule didn't have its own g sensor (it
does), you could figure out g forces just by tracking it and looking
at deceleration rates. WHATEVER it does on landing would have to be
gentler than Soyuz. Older versions of Soyuz hit 12+ g on the way
down. Aerodynamic studies indicate that Dragon V2 will peak under
3.5g.


If the mass on the crewed version will be significantly different,
perhaps NASA wants to emulate that mass as closely as possible for
liftoff, manoeuvering in space, re-entry and slashdown.


Things that don't matter just don't matter. That doesn't matter.


(Carrying cargo of same mass as what the crew would have would be
possible though).


CG would still presumably be different. You seem to be trying to make
the argument that the only way to man rate a system is to fly people
on it, which seems just a bit circular. And if you DO have to go that
route, just how many people do you fly, since Dragon V2 can carry up
to 7 people?


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn