SpaceX Dragon 2 Updates and Discussion - Thread 3

[woods170]

Neither the original design for Crew Dragon, nor the original design for Starliner, had manual abort capabilities. Manual abort capabilities were added because NASA asked the CCP providers to do so.

Woods, any idea for the official rationale for that decision?
Are the manual abort controls actually functional?

Yeah, the manual abort control on Crew Dragon (singular, not plural) is the T-shaped handle at the botten edge of the instrument panel. It is functional in that it instructs the flight computer to take Crew Dragon back to Terra Firma the soonest possible way. It does NOT manually initiate SuperDraco thrusters or anything; all that is done by the flight computer.
Using the handle is like fly-by-wire: issue a request to the flight computer to do something. Much like fly-by-wire on the F-16 is like the pilot requesting the flight-computer to turn the aircraft to the left when he/she turns the control stick to the left.
The rationale behind the decision is as I reported it earlier: having an escape possibility in the unlikely event that the crew sees trouble coming sooner than the flight computer does.

[Comga]

Close up photos:

https://twitter.com/SpaceX/status/1081405732107370497

And the full-size images

In the photo of the Dragon 2 capsule with the extended CAA, there are two dark ovals just below the edge of the nose cap and between the Super Draco housings. 
What are these?
The ACS Draco ports are covered for launch with something white.
Are they windows for docking aides like lidar?

[woods170]

Close up photos:

https://twitter.com/SpaceX/status/1081405732107370497

And the full-size images

In the photo of the Dragon 2 capsule with the extended CAA, there are two dark ovals just below the edge of the nose cap and between the Super Draco housings. 
What are these?
The ACS Draco ports are covered for launch with something white.
Are they windows for docking aides like lidar?

Likely not, given that the windows for the docking aides are all protected underneath the nose cap. See image below.

[Nomadd]

 So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

[Basto]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

Why would that need to be initiated by the crew though?  Seems like that scenario would have more time for ground controllers to issue new commands.

The paradigm shift away from a human at the wheel seems foreign and scary... but humans often make poor choices when under stress.

[su27k]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

There's a "Water Deorbit" button and a "Deorbit Now" button, I assume you press one them then press "Execute".

[Nomadd]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

Why would that need to be initiated by the crew though?  Seems like that scenario would have more time for ground controllers to issue new commands.

The paradigm shift away from a human at the wheel seems foreign and scary... but humans often make poor choices when under stress.

You assume comms failure isn't a scenario?

[Johnnyhinbos]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

There's a "Water Deorbit" button and a "Deorbit Now" button, I assume you press one them then press "Execute".

Thanks for that image su27k. Hadn’t seen as high fidelity of an image of the buttons before.

What the heck is Breakout?

[guckyfan]

Both "Water Deorbit" button and "Deorbit Now" sound like quite extreme emergency measures. When they can't reach the ISS but have some time a deorbit can be calculated and initiated from the ground to enable quick recovery. A few more hours in space are better than many hours in the water until recovery is possible. That's assuming water is prefered over land landing as the naming indicates.

[mme]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

See su27k’s response re: deorbit buttons. And for less “do it now!” Commands they have touchscreens. There are probably all sorts of crazy menus they can drill into.

edit: typos. Always typos.

[HMXHMX]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

There's a "Water Deorbit" button and a "Deorbit Now" button, I assume you press one them then press "Execute".

"Use only after landing"

Good advice!

[punder]

"Use only after landing"

Good advice!

Nice place for an old-fashioned safety cover.   

Perhaps that switch isn't even functional until splashdown is detected, and the legend is a little SpaceX joke.

Or a Photoshop job...

[AC in NC]

Nice place for an old-fashioned safety cover.   

It's a "new-fashioned safety cover".  The three "ledges" are pressed to flip down a plastic cover over all those buttons are emergencies.

See the same picture enlarged to highlight the connection of the plastic covers to the "Commands", "Power", and "Pyros" ledges.

[rpapo]

Nice place for an old-fashioned safety cover.   

It's a "new-fashioned safety cover".  The three "finger ledges" are pressed to flip down a plastic cover over all those buttons are emergencies.

"Pyros"   I thought that was bitter poison to the SpaceX people...

[Johnnyhinbos]

Nice place for an old-fashioned safety cover.   

It's a "new-fashioned safety cover".  The three "finger ledges" are pressed to flip down a plastic cover over all those buttons are emergencies.

"Pyros"   I thought that was bitter poison to the SpaceX people...

Pyros are required for the parachute system.

[biosehnsucht]

From looking at that picture, in the Pyros section there's a button to jettison the nose cone. Is that for emergencies or are they throwing it away on every landing ? Renders have always had it be retractable... so it can be reusable.

[woods170]

From looking at that picture, in the Pyros section there's a button to jettison the nose cone. Is that for emergencies or are they throwing it away on every landing ? Renders have always had it be retractable... so it can be reusable.

Those pyros are mostly for off-nominal situations.

- Nose cone jettison: that pyro is there to jettison the nose cone (in orbit) in case the nose cone fails to close after undocking from the ISS. The nose cone is not necessarily needed to protect the docking assembly on reentry. Just see how Cargo Dragon has an exposed CBM on reentry.
But having the nose cone in place, in it's opened position, is a NO-GO for reentry. Hence the capability being there to manually jettison the nose cone.

- Cut Mains. This pyro is there in case the flight computer fails to automatically jettison the main parachutes after splash-down. Failure to jettison the main parachutes after landing can lead to a scenario similar to what was witnessed on the Dragon C2+ mission: the capsule was dragged thru the water for hundreds of meters because one of the main parachutes was caught by the wind (see image below).

- The pyros for deploying the drogues and main parachutes are there to allow the crew to manually deploy those chutes in case the flight computer is incapable of doing so.

[geza]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

There's a "Water Deorbit" button and a "Deorbit Now" button, I assume you press one them then press "Execute".

Thanks for that image su27k. Hadn’t seen as high fidelity of an image of the buttons before.

What the heck is Breakout?

Pad/launch abort?

[woods170]

So, what happens when you stop calling it an abort and it's just an unscheduled return? Say, it can't dock because of a performance shortfall or mechanical difficulties, but it's not critical to return instantly. I assume they can do better than pull a handle. How do they implement commands for unscheduled maneuvers?
 Sorry about being so lazy if this was already covered.

There's a "Water Deorbit" button and a "Deorbit Now" button, I assume you press one them then press "Execute".

Thanks for that image su27k. Hadn’t seen as high fidelity of an image of the buttons before.

What the heck is Breakout?

Pad/launch abort?

No. The abort handle is for manually initiated pad/launch aborts.

The abort handle is circled in red in the image below.

[IntoTheVoid]

Thanks for that image su27k. Hadn’t seen as high fidelity of an image of the buttons before.

What the heck is Breakout?

I'm presuming that 'Breakout' is to force the capsule door open to allow them to physically get out of the capsule. Probably after landing, since the IVA suits aren't EVA suits.