Starship looks more and more like a space shuttle?

[cubinator]

2 hours ago, Wjolcz said:

Anybody knows any material that is glass-like and heat resistant?

Aerogel? Kinda brittle but absurdly light and insulating.

[farmerben]

 

Spoiler

 

The feathered reentry was first described by Dean Chapman of NACA in 1958.^[48] In the section of his report on Composite Entry, Chapman described a solution to the problem using a high-drag device:

It may be desirable to combine lifting and nonlifting entry in order to achieve some advantages... For landing maneuverability it obviously is advantageous to employ a lifting vehicle. The total heat absorbed by a lifting vehicle, however, is much higher than for a nonlifting vehicle... Nonlifting vehicles can more easily be constructed... by employing, for example, a large, light drag device... The larger the device, the smaller is the heating rate.

Nonlifting vehicles with shuttlecock stability are advantageous also from the viewpoint of minimum control requirements during entry.

... an evident composite type of entry, which combines some of the desirable features of lifting and nonlifting trajectories, would be to enter first without lift but with a... drag device; then, when the velocity is reduced to a certain value... the device is jettisoned or retracted, leaving a lifting vehicle... for the remainder of the descent.

https://en.wikipedia.org/wiki/Atmospheric_entry

 

 

 

Spoiler

 

 

 

[Wjolcz]

11 hours ago, cubinator said:

Aerogel? Kinda brittle but absurdly light and insulating.

Wouldn't aerogel ablate really quickly without any protection?

[magnemoe]

43 minutes ago, Wjolcz said:

Wouldn't aerogel ablate really quickly without any protection?

Yes, you can probably make some who is more resistant but not something who work with rapid reuse. 

Pretty sure they go with ceramic but with much harder tiles than the space shuttle as you don't care so much if some heat leaks trough, might have an extra insulated layer between the hull and the tiles. 

[mikegarrison]

20 hours ago, Dragon01 said:

 it should glide surprisingly well. Not quite like the Shuttle, but perhaps even enough to make glide landing an abort option.

Not a chance. Yes, sometimes shapes like that can work as a lifting body, but it would need landing gear. Here's what a lifting body looks like if it lands without landing gear:

 

Edited November 25, 2019 by mikegarrison

[StrandedonEarth]

4 hours ago, mikegarrison said:

Not a chance. Yes, sometimes shapes like that can work as a lifting body, but it would need landing gear. Here's what a lifting body looks like if it lands without landing gear:

 

Wasn’t Steve Austin aboard that thing? 

[Guest]

4 hours ago, mikegarrison said:

Not a chance. Yes, sometimes shapes like that can work as a lifting body, but it would need landing gear. Here's what a lifting body looks like if it lands without landing gear:

Yes exactly. See how it falls into a billion pieces on touchdown? Oh wait, it doesn't. It kind of proves my point, really. FIY, the pilot survived. For an abort procedure, this is all you're asking for. If the engines die, it'd make sense for Starship to attempt a belly landing either on water or a specially prepared runway. Without propellant, it'd have very little density for its weight, and more than enough lift to land in a somewhat controlled manner.

[.50calBMG]

But starship doesn't fly that way. It falls like a skydiver. It doesn't have the proper control surfaces to fly like that. The only time it will be flying somewhat nose first is on re-entry, but still at such a high AOA that the lift coming from the body is a secondary side effect from coming into the atmosphere at an angle, which will happen to basically any shape moving that quickly.

[magnemoe]

2 hours ago, .50calBMG said:

But starship doesn't fly that way. It falls like a skydiver. It doesn't have the proper control surfaces to fly like that. The only time it will be flying somewhat nose first is on re-entry, but still at such a high AOA that the lift coming from the body is a secondary side effect from coming into the atmosphere at an angle, which will happen to basically any shape moving that quickly.

Yes also starship will try to kill most of its horizontal speed before flipping upright, also depend a bit on aiming, you probably want to keep some as it help with the flip but guess 50-100 km/h would be enough, you are falling faster, say you are at 45 degree angle and folds the lower fins back while extend the upper to max and you will flip to 90 degree and probably continue but then the engine fires, you use flaps to help stabilize it upright and gimbal also help.

If engine don't work well you fire another and you still has one engine left, see engine fail as an unlikely fail source. See the fins or software as more likely
It also depend on how aggressive you want to land, an manned mission is likely to have more fuel and flip higher while tankers would not have full header tanks once they nail this. 

[mikegarrison]

2 hours ago, Dragon01 said:

Yes exactly. See how it falls into a billion pieces on touchdown? Oh wait, it doesn't. It kind of proves my point, really. FIY, the pilot survived. For an abort procedure, this is all you're asking for. If the engines die, it'd make sense for Starship to attempt a belly landing either on water or a specially prepared runway. Without propellant, it'd have very little density for its weight, and more than enough lift to land in a somewhat controlled manner.

I know the pilot survived, but with pretty severe injuries.

At the speeds required to make something like that (or like Starship) have enough lift to maintain any sort of reasonable vertical velocity, it must have a very large horizontal velocity. At those speeds, water is pretty nearly the same thing as land, except you can also drown after the crash.

6 minutes ago, magnemoe said:

If engine don't work well you fire another and you still has one engine left, see engine fail as an unlikely fail source. See the fins or software as more likely
It also depend on how aggressive you want to land, an manned mission is likely to have more fuel and flip higher while tankers would not have full header tanks once they nail this. 

Doesn't matter how many engines you have if there is a problem in your fuel delivery system (or just a lack of fuel in the tank).

[magnemoe]

4 minutes ago, mikegarrison said:

I know the pilot survived, but with pretty severe injuries.

At the speeds required to make something like that (or like Starship) have enough lift to maintain any sort of reasonable vertical velocity, it must have a very large horizontal velocity. At those speeds, water is pretty nearly the same thing as land, except you can also drown after the crash.

Doesn't matter how many engines you have if there is a problem in your fuel delivery system (or just a lack of fuel in the tank).

if you have an lack of fuel you launch an tanker or rescue craft or abort to Africa if that is not an option. 
You use the header tanks for the deorbit burn, low chance that system will fail during reentry and if it fail somehow you would not notice before the burn, yes they might pump back the fuel and oxidizer in the feed lines during reentry and fill them back on during atmospheric flight, if the pipes are the one inside the raceway they will empty them, if they pass trough the tanks it don't matter much. 

An abort system would be better and as the header tanks is above the crew module its an easy way to make an abort system. 

[mikegarrison]

Right, yes, just like the Space Shuttle in the final years -- if you have a problem you know about in orbit then you send another ship up to either fix it or at least recover the crew. But if you have a problem you only find out about after you have started re-entry? You have a *very* limited amount of time to solve it.

[sevenperforce]

On 11/23/2019 at 8:40 PM, Boyster said:

Yeah, i really hope so as well.I love SpaceX but the more i think about Starship and Earth, it doesnt make sense to my mind.For other planets for sure but here...i think like its not really any better than Space Shuttle, even so feels more dangerous and complicated.

Starship needs to fly to Mars, enter and land, refuel, fly back to Earth, and enter and land. So they had to design something that would be able to do controlled EDL on both worlds.

[magnemoe]

46 minutes ago, mikegarrison said:

Right, yes, just like the Space Shuttle in the final years -- if you have a problem you know about in orbit then you send another ship up to either fix it or at least recover the crew. But if you have a problem you only find out about after you have started re-entry? You have a *very* limited amount of time to solve it.

Abort to Africa is an option if refueling is not, note that refueling is an integrated part of the starship system so one fallback might even be an powered reentry on earth. 

[mikegarrison]

58 minutes ago, magnemoe said:

Abort to Africa is an option if refueling is not, note that refueling is an integrated part of the starship system so one fallback might even be an powered reentry on earth. 

We appear to be talking at cross-purposes. Africa is not a land of magic -- why would "abort to Africa" be something for re-entry problems? Once the craft starts re-entry, it's probably completely committed. If something jammed or broke in the fuel/oxidizer delivery system, this would mean no amount of redundant engines meant anything. With a powered landing as the only option, there *must* be fuel delivery to the engines or the ship is a total loss.

I'm not saying it will happen. It's just that airplanes or helicopters, for instance, have flight modes which they can use to attempt safe landings in an unpowered state. Starship will not have that, because even if it can generate enough lift to make a controlled glide, it will be moving way too fast to safely belly land or ditch. (And besides that, I don't think it has the control surfaces to maintain a controlled lifting glide anyway.)

Starship is not unique in having a non-redundant landing option. Pretty much all spacecraft have had this issue to date. But it apparently will be the first Earth orbital spacecraft whose non-redundant landing mode is rocket power.

[magnemoe]

3 hours ago, mikegarrison said:

We appear to be talking at cross-purposes. Africa is not a land of magic -- why would "abort to Africa" be something for re-entry problems? Once the craft starts re-entry, it's probably completely committed. If something jammed or broke in the fuel/oxidizer delivery system, this would mean no amount of redundant engines meant anything. With a powered landing as the only option, there *must* be fuel delivery to the engines or the ship is a total loss.

I'm not saying it will happen. It's just that airplanes or helicopters, for instance, have flight modes which they can use to attempt safe landings in an unpowered state. Starship will not have that, because even if it can generate enough lift to make a controlled glide, it will be moving way too fast to safely belly land or ditch. (And besides that, I don't think it has the control surfaces to maintain a controlled lifting glide anyway.)

Starship is not unique in having a non-redundant landing option. Pretty much all spacecraft have had this issue to date. But it apparently will be the first Earth orbital spacecraft whose non-redundant landing mode is rocket power.

Going subobital and landing in Africa was an shuttle abort mode, unlike the shuttle starship is not limited to one runway but can land anywhere pretty flat. 
Fuel delivery system, or at least the centralized one is very simple its an valve on top of the header tank, then it might be an central cutoff for the three surface level engines. They each has an cutoff and an main regulator valve but this is redundant, assume the valve controls are also redundant as in it has two motors.

Starship can not glide land trying to make it capable of it would be much heavier than an abort system and unlike an abort system it would not show up until to late to use because the flight profile. 
Some pointed out that the reason they went for 2 set of fins rather than Tintin was that Tintin would put center of drag in front of center of mass making it dynamic unstable while an starship with fins folded back a bit would have center of drag behind center of mass making it stable. 
 

[Serenity]

9 hours ago, mikegarrison said:

Starship is not unique in having a non-redundant landing option. Pretty much all spacecraft have had this issue to date. But it apparently will be the first Earth orbital spacecraft whose non-redundant landing mode is rocket power.

What do you mean pretty much all spacecraft?

Most of them have redundant abort/parachute systems .

[magnemoe]

1 hour ago, Boyster said:

What do you mean pretty much all spacecraft?

Most of them have redundant abort/parachute systems .

Agree, yes capsules have multiple parachutes but one hatch and release system as I understand. Granted this can be build very reliable.

An design like starship, the shuttle, the air force spaceplane and dreamliner has way more failure modes than an capsule, yes capsule maneuver on the way down to reduce g forces and to aim but this is not required on an return from orbit. 

[mikegarrison]

2 hours ago, Boyster said:

What do you mean pretty much all spacecraft?

Most of them have redundant abort/parachute systems .

Typically they can survive the failure of one parachute, but they will crater if the whole parachute system fails. This is similar to Starship having redundant rockets but will fail if something (like fuel problems) systemically prevents all rockets from working.

Edited November 26, 2019 by mikegarrison

[Serenity]

28 minutes ago, mikegarrison said:

Typically they can survive the failure of one parachute, but they will crater if the whole parachute system fails. This is similar to Starship having redundant rockets but will fail if something (like fuel problems) systemically prevents all rockets from working.

Hey if it works like airplanes that can fly even with one engine then i am fine with it.

If it has multiple ways to keep some rockets alive and still make a somewhat safe land, then its perfect.

We have to remember that we talking about deploying parachutes and keeping rockets alive.Thats so different, it might look the same as a number, but for the hatch of parachutes to fail...i mean..

I bet the odds are way lower than having a rocket/fuel system fail.

But yeah its true in the end i see your point of most of spacecrafts in the end depending in one thing that if it fails there is no return.

Edited November 26, 2019 by Boyster

[sevenperforce]

On 11/25/2019 at 4:11 PM, mikegarrison said:

With a powered landing as the only option, there *must* be fuel delivery to the engines or the ship is a total loss.

I'm not saying it will happen. It's just that airplanes or helicopters, for instance, have flight modes which they can use to attempt safe landings in an unpowered state. Starship will not have that, because even if it can generate enough lift to make a controlled glide, it will be moving way too fast to safely belly land or ditch. (And besides that, I don't think it has the control surfaces to maintain a controlled lifting glide anyway.)

Starship is not unique in having a non-redundant landing option. Pretty much all spacecraft have had this issue to date. But it apparently will be the first Earth orbital spacecraft whose non-redundant landing mode is rocket power.

Unpowered landing is not a huge problem for airplanes. It's tough for helicopters, but doable. With airplanes it is fairly straightforward.

Comparing Starship's engines to airplane engines, then, is a bit of a tricky proposition because their role is different. Airplanes can land unpowered but they cannot land without control surfaces. Multiple engine failure on Starship would be less like dual-engine-out on a jetliner and more like locked elevators and ailerons on a jetliner. If a jumbo jet loses its ailerons and elevators, it is dead. In contrast, as long as 1 of Starship's 3 SL engines is working and at least 2 of its 4 control surfaces are working, it can land.

I remember watching this landing live and thinking about fault tolerance on landing gear....

 

On 11/26/2019 at 3:25 AM, mikegarrison said:

This is similar to Starship having redundant rockets but will fail if something (like fuel problems) systemically prevents all rockets from working.

If a systematic problem prevents all control surfaces on a jetliner from working, it would crash. This is why control surfaces have triple+ redundant subsystems. The engines on Starship all have independent turbopumps, plumbing, ignition systems, and so forth for the same reason.

If the tanks are breached and there is no propellant, then yes, Starship will crash. But that seems obvious. If an airliner's wings break in half, it will crash too.

[AngrybobH]

4 hours ago, sevenperforce said:

If a systematic problem prevents all control surfaces on a jetliner from working, it would crash. This is why control surfaces have triple+ redundant subsystems

United Airlines flight 232 managed a quite amazing landing (mostly crash) with a failure mode that was considered unflyable(all 3 hydraulic systems failed). I really doubt that starship would have a capability to pull something out like that with a similar level of failure. Of course, I would still get on a starship if it were man rated.

[StrandedonEarth]

1 hour ago, AngrybobH said:

United Airlines flight 232 managed a quite amazing landing (mostly crash) with a failure mode that was considered unflyable(all 3 hydraulic systems failed). I really doubt that starship would have a capability to pull something out like that with a similar level of failure. Of course, I would still get on a starship if it were man rated.

Yes, that was a remarkable crash landing, saving around 100 lives IIRC. When that failure was run through the simulator, no other pilots could even get to the airport. The key was that they still had engine power, so they steered it with differential throttling. 

If StarShip had a complete engine failure, it would hit like a brick. I wonder how many dorsal parachutes would be needed to slow it enough for a survivable crash landing? Not pleasant, but neither is an ejection seat. Severing the cabin would help, but that mechanism just becomes another failure point if it triggers by accident. 

[magnemoe]

6 hours ago, sevenperforce said:

Unpowered landing is not a huge problem for airplanes. It's tough for helicopters, but doable. With airplanes it is fairly straightforward.

Comparing Starship's engines to airplane engines, then, is a bit of a tricky proposition because their role is different. Airplanes can land unpowered but they cannot land without control surfaces. Multiple engine failure on Starship would be less like dual-engine-out on a jetliner and more like locked elevators and ailerons on a jetliner. If a jumbo jet loses its ailerons and elevators, it is dead. In contrast, as long as 1 of Starship's 3 SL engines is working and at least 2 of its 4 control surfaces are working, it can land.

I remember watching this landing live and thinking about fault tolerance on landing gear....

 

If a systematic problem prevents all control surfaces on a jetliner from working, it would crash. This is why control surfaces have triple+ redundant subsystems. The engines on Starship all have independent turbopumps, plumbing, ignition systems, and so forth for the same reason.

If the tanks are breached and there is no propellant, then yes, Starship will crash. But that seems obvious. If an airliner's wings break in half, it will crash too.

I say unpowered landings is an serious problem if you can not reach an airstrip, its an reason why two engine planes long was not allowed to be used over the Pacific or the Atlantic. 
Its still lots of paperwork to get an new engine qualified for this. You have two issues, today first is probably fuel use, with one engine out you need to run the reminder at higher trust, you also has to use rudder to compensate for off center trust increasing drag. Second is that the second engine can manage the increased trust until it reach the emergency landing runway but I assume this is solved today.  
Events  like one engine fails during takeoff and you will redline the reminding engine hard, but then you just turn around and land. 

An helicopter can land everywhere, outside of cliffs, this is an common KSP issue, you do not want to get into the mountain range west of KSP. 
You don't want cities or forest either, but else you are fine, as long as you are high enough up as you need some height or speed to use counter rotation. 
Still helicopter are much less safe than planes. 

[sevenperforce]

On 11/27/2019 at 3:01 PM, AngrybobH said:

United Airlines flight 232 managed a quite amazing landing (mostly crash) with a failure mode that was considered unflyable(all 3 hydraulic systems failed). I really doubt that starship would have a capability to pull something out like that with a similar level of failure. Of course, I would still get on a starship if it were man rated.

Yes, that was quite amazing. They were able to use differential thrust to produce some degree of control. Fortunately the control surfaces were trimmed for roughly level flight.

That's kind of like if all four of Starship's control surfaces became locked in a stable config and they had to use hot-gas thrusters for roll and pitch. Of course, it may have propellant reserve problems. It can land with extra reserves when carrying humans.

Starship will have completely, truly independent drive systems for each of the four control surfaces, so there is no such single failure mode.

On 11/27/2019 at 5:28 PM, magnemoe said:

An helicopter can land everywhere, outside of cliffs, this is an common KSP issue, you do not want to get into the mountain range west of KSP. 
You don't want cities or forest either, but else you are fine, as long as you are high enough up as you need some height or speed to use counter rotation. 
Still helicopter are much less safe than planes. 

Helicopters are much closer to Starship for this particular analogy. For a jetliner, the engines are independent of the glide mode; for a helicopter, the engine is the glide mode. If a helicopter lost hydraulic control of its main rotor it would be unable to autorotate.