SpaceX Falcon 9/Dragon COTS Demo (C2+) GENERAL DISCUSSION

[Lars_J]

If crewed Dragon had to do a water landing, would they use the SuperDracos, or just go with chutes?

We are not even sure that crewed Dragon will have chutes. I am guessing that it will but I don't think that we know for sure. 

SpaceX has stated that it will have chutes as backup.

[Robert Thompson]

Any media / publicity numbers for this moment?

[lcs]

We had a nice camera view all the way up, so why can't we get a similar camera view while coming down?

I know there's a blackout period due to re-entry plasma, but outside of that can't they give us something?

You need a stable platform to get a high-bandwidth satellite link.  Not easy from aircraft or boats bobbing around in the water. 

[plank]

Nobody seems to be celebrating something went wrong?   

[psloss]

Nobody seems to be celebrating something went wrong?   

Party thread:
http://forum.nasaspaceflight.com/index.php?topic=28920.0

[yg1968]

Nobody seems to be celebrating something went wrong?   

I am still waiting for the boats to fish Dragon out of the water before celebrating.

[sanman]

So I'm thinking that seawater must inflict a bit of corrosion on a capsule. Will the later helicopter-precision land-based landings then help keep things more reusable than if they'd splashed down at sea?

[Ben the Space Brit]

So I'm thinking that seawater must inflict a bit of corrosion on a capsule. Will the later helicopter-precision land-based landings then help keep things more reusable than if they'd splashed down at sea?

There is probably quite a bit of structural damage from the splash-down too. How many instantaneous gees do returning craft pull on contact with the water?

[Nomadd]

We had a nice camera view all the way up, so why can't we get a similar camera view while coming down?

I know there's a blackout period due to re-entry plasma, but outside of that can't they give us something?

You need a stable platform to get a high-bandwidth satellite link.  Not easy from aircraft or boats bobbing around in the water. 

 Guess I better take all those 3 mbs ku band dishes back off my boats.

[docmordrid]

So I'm thinking that seawater must inflict a bit of corrosion on a capsule. Will the later helicopter-precision land-based landings then help keep things more reusable than if they'd splashed down at sea?

There is probably quite a bit of structural damage from the splash-down too. How many instantaneous gees do returning craft pull on contact with the water?

IIRC the C1 spashdown was only about 12 fps - pretty low because of those huge 'chutes.

[SiriusGrey]

So I'm thinking that seawater must inflict a bit of corrosion on a capsule. Will the later helicopter-precision land-based landings then help keep things more reusable than if they'd splashed down at sea?

There is probably quite a bit of structural damage from the splash-down too. How many instantaneous gees do returning craft pull on contact with the water?

From the SpaceX update page on the drop test:

Under nominal conditions, astronauts would experience no more than roughly 2-3 g’s during this type of descent—less than you’d experience at an amusement park.

[Ben the Space Brit]

From the SpaceX update page on the drop test:

Under nominal conditions, astronauts would experience no more than roughly 2-3 g’s during this type of descent—less than you’d experience at an amusement park.

I'm presuming that is sustained, which sounds about right (they'd want to keep it close to the Shuttle experience, after all).  I meant the momentary force at the moment of spacecraft contact with the water's surface.  I remember Jim once mentioning an eye-poppingly high figure.

[SiriusGrey]

They mention 16-18 ft/s which is 4.9-5.5 m/s. This is equivalent to a fall from 2.4-3.1 m.

Assuming for simplification that they sink ~0.5m into the water (guesstimate) at constant deceleration, that deceleration would be around 2.5g-3g.

[Jim]

 
 Guess I better take all those 3 mbs ku band dishes back off my boats.

That is for downlink.  Pointing requirements for uplink quite different

[Jim]

Agree it would be the logical place, however isn't this a Boeing owned facility?  Thought Sealaunch only uses the services?   

It is Energia owned.

[Jim]

I thought Shuttle purged its fuel before re-entry

Some of it, not all.

It emptied the FRCS.

[Jorge]

Why do they jettisonned the Trunk so late?

You de-orbit with it to control when it re-enters.  (Like Soyuz does.)

So that the trunk doesn't because space debris? It seems like an additionnal failure point (especially if you had crew in the capsule).

If it didn't separate on a manned flight, they might be able to do an abort burn to raise the perigee back up to give them time to troubleshoot and fix. That would likely imply having to do a water landing though, because they would have burned more propellant on the abort back to orbit, and the second deorbit burn.

~Jon

If the umbilicals separated but the trunk did not, they wouldn't have long due to loss of power/heating. Couple of orbits, based on C1.

[Jorge]

Why do they jettisonned the Trunk so late?

You de-orbit with it to control when it re-enters.  (Like Soyuz does.)

So that the trunk doesn't because space debris? It seems like an additionnal failure point (especially if you had crew in the capsule).

It's nothing new; every other capsule has done it that way.

[Jorge]

Question - they say the Dragon de-orbit burn is a 100m per second burn.

1g, if I recall, is about 10m/s.

Does that mean Dragon is experiencing ~10g deceleration?

Don't confuse velocity with acceleration. 1g = 9.8m/s^2, not 9.8 m/s.

[peter-b]

100 m/s over 600 s gives a deceleration of 1/6 m/s^2, or about one sixtieth of a gravity.