On 7/19/2019 12:01 PM, Niklas Holsti wrote:
On 19-07-19 18:13 , David Spain wrote:
On 7/19/2019 9:19 AM, Niklas Holsti wrote:

They might even use propulsive landing for cargo flights.

I forgot about the landing legs that are needed for that. They may have
been removed from the Dragon2 design and might be hard to refit.

Yes that is correct they have been removed from the architecture. I had
missed that point as well. Truth is, AFAIK the original design called to
the landing legs to extrude from the heat shield. NASA was definitely
not big on this idea. And to the best of my knowledge, other than the V2
mock-up this was never implemented.

When first shown I was surprised they planned to do it that way rather
than just follow the method they adopted on F9, and just have them swing
down from the body of the capsule.

I suppose they could still go for propulsive landing over water. At sea
and then move to a large fresh water tank on dry ground? Or if
up-welling steam is a problem maybe a high boiling point oil?

If that was the plan before replacing the check valve(s) with burst
disks, I wonder if that remains the plan?

If so it would imply that they (SpaceX) intended to fly all the way down
with pressurized engines all along anyway,

AIUI, there is an actuated valve at the He tank, before the check
valves, which would not be opened until just before the SuperDracos are
fired. So the engines would not be pressurized until needed.


Yeah but once needed always on is the point. After a landing I'd think
you'd want to vent that helium pressure off. But maybe you shouldn't
until the bi-propellant is drained? And if back flow is a problem with a
check valve you can imagine the issues you might run into if you kill
helium pressure with a now a burst burst disk.

Not enough data...

Dave