SpaceX News

[Giorgio]

Tile survival whether on chopsticks or a pad (landing impact shockwave) is yet to be proven. Greater shock absorbing is possible with the chopsticks, still that said, Mars will have no chopsticks in the beginning. Perhaps the issue with landing shockwave & tiles is why EM has kept reentry active cooling on the table?
There will be ship legs for Moon & Mars.

You are right for landing legs, there must be landing legs for Mars and Moon landing, but there is no need of heat protection tiles for moon and most probably for Mars too.
Considering that the max temperatures during Mars entry for previous probes was around 1000C, it would mean that the thermal flux could be probably be absorbed directly by the Stainless steel skin.

I believe this is one of the point they will investigate in their first landing attempt and if proven right it would make more sense to have a ship for mars/moon landings to act as shuttle from earth orbit.

[KitemanSA]

Yes I was talking about the booster, but in general the issue is the same also for the ship even if more limited.
Your point on the forces during acceleration is a good one, and for sure the design of the ship skirt is more strong than the booster.
But one very important point is that the forces on the skirt of the ship during launch are progressive from Zero to MaxQ over a very long time, while during landing the forces goes from value "X" to value zero in a very short time. This force impulse is what creates the pressure wave propagation into the skirt that i was mentioning in my first post, and this is why you need shock absorbers.

The force on the ship skirt starts at a high level due to being fully loaded with propellent under 1g. It steps up by a factor of, what, three times (?) at liftoff (hardly “zero”) and climbs thru Max-Q. At landing, the force on the skirt starts at zero (ship hover at touchdown) and climbs to the empty weight of the ship over as long as they wish thru the slow reduction of thrust and via compliance of the landing grid and its support systems (spring/dampers). All in all, impuse approximates ZERO. That is the whole point!

[KitemanSA]

Tile survival whether on chopsticks or a pad (landing impact shockwave)

What part of NOT PAD are you not getting? Compliant grill.

[Giorgio]

The force on the ship skirt starts at a high level due to being fully loaded with propellent under 1g. It steps up by a factor of, what, three times (?) at liftoff (hardly “zero”) and climbs thru Max-Q. At landing, the force on the skirt starts at zero (ship hover at touchdown) and climbs to the empty weight of the ship over as long as they wish thru the slow reduction of thrust and via compliance of the landing grid and its support systems (spring/dampers). All in all, impuse approximates ZERO. That is the whole point!

So your idea is to have a grid with Dampers over which the rocket will land? Same principle of the actual landing system but instead of landing over 2 pins on the top it lands over a grid in the bottom that incorporate all the structures for absorbing all the dynamic landing forces.
Did I understand it well?

[KitemanSA]

The force on the ship skirt starts at a high level due to being fully loaded with propellent under 1g. It steps up by a factor of, what, three times (?) at liftoff (hardly “zero”) and climbs thru Max-Q. At landing, the force on the skirt starts at zero (ship hover at touchdown) and climbs to the empty weight of the ship over as long as they wish thru the slow reduction of thrust and via compliance of the landing grid and its support systems (spring/dampers). All in all, impuse approximates ZERO. That is the whole point!

So your idea is to have a grid with Dampers over which the rocket will land? Same principle of the actual landing system but instead of landing over 2 pins on the top it lands over a grid in the bottom that incorporate all the structures for absorbing all the dynamic landing forces.
Did I understand it well?

Do you understand it well? From the apparent snideness of your tone, I suspect not. But maybe I miss-read you.
The issue with catching at the top is the fragility of the TSP tiles. And with the repositioned flaps, there are no centerline hard points that do not interrupt the fragile tiles. Landing on a compliant grid with damped springs at the corners (4 if square, 6 if hex…) avoids interaction between a moving sheet of ceramic tiles and a massive moving pair of clamp-arms.
Just a thought.
Heck, they could rig the grid over the flame trench at the gun range and land there for added safety! Build the grid-work onto one of their newer mobile carriers. Hmmm.

[Giorgio]

Do you understand it well? From the apparent snideness of your tone, I suspect not. But maybe I miss-read you.

There was no snideness at all, I was actually trying to understand what you had in mind.
Forums posts are prone to bend one's intentions unfortunately.

The issue with catching at the top is the fragility of the TSP tiles. And with the repositioned flaps, there are no centerline hard points that do not interrupt the fragile tiles. Landing on a compliant grid with damped springs at the corners (4 if square, 6 if hex…) avoids interaction between a moving sheet of ceramic tiles and a massive moving pair of clamp-arms.
Just a thought.
Heck, they could rig the grid over the flame trench at the gun range and land there for added safety! Build the grid-work onto one of their newer mobile carriers. Hmmm.

So it is like I imagined.
I am not convinced it will work unless you increase the footprint of the landing area by adding landing legs as I believe the actual center of gravity of the Spaceship is still pretty high when the rocket is almost empty, even more so for the next gen Spaceship that is even taller.
The issue than will be to see if the tradeoff weight between adding legs and structural supports to the Spaceship is beneficial versus potential tile damage.
Unfortunately I think that this is a question that only SpaceX can reply.
That said, a system like the one you are envisioning can indeed work as I don't see any particular engineering issues for the ground equipment side.

[KitemanSA]

The issue with catching at the top is the fragility of the TSP tiles. And with the repositioned flaps, there are no centerline hard points that do not interrupt the fragile tiles. Landing on a compliant grid with damped springs at the corners (4 if square, 6 if hex…) avoids interaction between a moving sheet of ceramic tiles and a massive moving pair of clamp-arms.
Just a thought.
Heck, they could rig the grid over the flame trench at the gun range and land there for added safety! Build the grid-work onto one of their newer mobile carriers. Hmmm.

So it is like I imagined.
I am not convinced it will work unless you increase the footprint of the landing area by adding landing legs as I believe the actual center of gravity of the Spaceship is still pretty high when the rocket is almost empty, even more so for the next gen Spaceship that is even taller.

They landed SN15 (?) on a solid concrete pad with itty bitty landing stubs that did not provide any extra “stance” Indeed, they did it with the rocket exhaust careening out from under the skirt thru the tiny gap provided by the landing stubs. Seems the greater controlability of the exhauster thru the grill would make the landing easier than what they already did.
But they seem to have decided on a different path. Too bad!

[ladajo]

Flight 9 executed, arguably once again proving the axiom "Space is Hard".
I would call it a 2 steps forward, 1 step back event.
Booster 14 successful 2nd use for boost (B14-2), then died a heroic death testing the limits of re-entry to landing profiles. It made it all the way employing a high angle of attack falling profile (more friction, less burn needed to slow for landing concept) to the full landing braking burn, then ka-boom.
Ship 35 successful launch atop B14-2, stage hot separation testing a new Booster clearing technique successfully, orbital burn was good, then once on (sub) orbit, attitude control was lost due to a leak somewhere bleeding off ullage gas employed for control. Accelerating tumble, with uncontrolled re-entry and break-up over Indian Ocean. S35 did not get to deploy dummy Starlink satellites as cargo door failed to fully open. Loss of attitude control precluded an on orbit engine re-light test. Re-entry testing of heat shield options also not done due to break-up.

Of note, Flights 7 & 8 ships failed to survive orbital insertion burns, both failing at end of burn sequence for distinct reasons, first was a fuel harmonics issue, second was an engine failure. S35 is assessed to not have either issue as a result of changes made. New (old) issue of leaking ullage to be corrected for Flight 10, maybe some other improvements too. Mush says SpaceX will be stepping up Starship flight cadence to about 3 week intervals going forward. FAA and NASA have already signed off on increased flight tempo.

[baking]

I've not heard him called that before.

[KitemanSA]

Flight 9 executed, arguably once again proving the axiom "Space is Hard".

Space is easy. ORBIT is hard. New Shepard vs New Glen.
Just quoting.

[KitemanSA]

I've not heard him called that before.