Problems with the Starship tiles?

RGClark · 2022-09-21 11:02:09

Saw this discussed on the NASASpaceflight forum:

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Don't know if you know about it but this site has some useful articles

https://www.nasaspaceflight.com/2022/09 … f-testing/

As previously reported, Ship 26 and Ship 27 may be undergoing a radical change in plans, omitting thermal protection system (TPS) tiles and not installing aerodynamic flaps. So far, this seems to be holding true with parts of Ship 26 seen now bare of tiles and on stand-by at Starbase’s ring yard for stacking.
Ship 27 parts are also proceeding similarly to Ship 26 parts. In some cases, there seems to be a strange mix-match of parts for these vehicles.

https://www.nasaspaceflight.com/2022/08 … nal-tests/

While all of this is happening, workers have been seen doing unusual work on future Starship vehicles and more concretely on Ship 26.
Workers were seen removing Thermal Protection System (TPS) tiles and blankets from Ship 26’s nosecone, while some of its barrel sections, which were supposed to receive the installation pins for the TPS tiles, are already staged outside in the ring yard ready for stacking.
While there has not been any official reason provided, some indications point to SpaceX trying to fast-track Ship 26 and Ship 27 builds by not installing TPS tiles or even flaps in order to quickly deliver Starlink v2 satellites into orbit, which the company may need in order to accelerate deployment once Starship proves itself worthy of going into orbit

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https://forum.nasaspaceflight.com/index … msg2409134

With every test firing of the Starship some tiles pop off. There is some speculation Starship may be launched on the first test flight without the tiles, obviously in an expendable mode.

Here’s a picture of the pins that hold on the tiles:

It seems you could get stronger type pins than that. For example you could use spring-loaded wing nuts:

Apparently SpaceX does not want to glue the tiles on like what happened with the shuttle because it takes too much maintenance time for replacement and refurbishment.

But with the wing nuts you can adjust the strength to be removable but strong enough to hold on during flight.

By the way, according to the discussion in that thread on NasaSpaceflight.com SpaceX is looking to improve on the tiles they are using. Perhaps, GW’s ultra lightweight, reusable tiles could come to the rescue?

GW Johnson - Reusable Ceramic Heat Shields - 16th Mars Society Convention.
https://youtu.be/3MXYY3jnNr0

Robert Clark

Last edited by RGClark (2022-09-21 22:11:40)

GW Johnson · 2022-09-22 16:06:49

Dunno how my stuff might help, for 2 reasons. (1) it's a panel made to a backing plate, which bolts to vehicle framing, not its skin. That is NOT what Starship has. Putting such a panel atop skin is way too heavy! (2) I show inadequate temperature capability for Earth entry at 8 km/s, even if blackened for emissivity 0.8, unless the radius of curvature is very flat indeed! Starship's is not!

The other consideration here is what do you do with Starship if the entry speed exceeds 8 km/s? Such as 10.9 coming back from the moon? Or 12-17 coming back from Mars? Above 10 km/s, only an ablative is feasible! There is no re-radiative cooling for a refractory, because the plasma sheath about the vehicle is getting opaque to thermal IR. It's already opaque to radio and radar at only 8 km/s.

GW

SpaceNut · 2022-09-22 20:33:35

You know you have a problem when the moving of the ship to the launch pad has them falling off.
SpaceX Struggles With Heat Shield Tiles On World’s Largest Rocket

They have also fallen off during the engine tests as well as during the test flights of the starship as well.
Just think how many will fall off during a flight to orbit and how the number and location would cause a loss of ship and people that we experienced with 2 shuttles.

GW Johnson · 2022-09-23 09:10:30

SpaceX's means of adding the PICA-X tiles is showing deficiencies. Those have to be fixed. Period.

The steel hull of the ship coming back during entry at 60 degree angle-of-attack is very nearly broadside to the wind, with air pressures on its windward side at peak deceleration in the 1 ton per square foot range. Part of the strength that keeps it from collapsing will be the tank framing, and part will be its internal pressure. Burn a hole in the tank, and you lose the pressure; it is NOT double-hull!

Anybody else here foresee the danger of that?

The landing propellant is in the smaller header tank nested inside the main tank. That isolates it thermally from the heating experienced at the shell of the main tank. But if you burn through during entry, that allows very hot gas entry into the tank (assuming it does not collapse from loss of pressure), which then causes higher evaporation rates for the landing propellant in the header tank.

Anybody else here foresee a problem with that?

What I found half a century ago in the hypersonic wind tunnel was an interaction of the separated flow over the backside of the nose with the twin vortices formed by the cross-flow component at high angle of attack. This pulled the separated flow back down into contact with the lee-side of the nose, which destroyed windscreens in seconds for any imaginable shuttle nose shape.

The same flow physics should obtain about Starship at 60 degree angle of attack during entry. The leeside of its nose is very likely to get strongly scrubbed by a jet of hypersonic air coming right over the nose, and pulled down to contact by those twin leeside vortices.

Right now, none of the Starship prototypes has any ablative tiles there, and in the crewed design, that is where they envision putting windows. Does anybody else here foresee a possible problem with that?

Prediction: they will lose a lot of these vehicles in orbital flight attempts, especially during entry and maybe landing, before they get this design right. It is still one hell of a long way from being the operational spaceship all of us want it to be.

GW

Last edited by GW Johnson (2022-09-23 09:12:58)

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#1 2022-09-21 11:02:09

Problems with the Starship tiles?

#2 2022-09-22 16:06:49

Re: Problems with the Starship tiles?

#3 2022-09-22 20:33:35

Re: Problems with the Starship tiles?

#4 2022-09-23 09:10:30

Re: Problems with the Starship tiles?

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