The ship will not have a reentry burn - it will aerobrake.
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SpaceX Starship - Integrated Flight Test #2 - Starbase TX - Including Post Launch Dissection
- Thread starter Grendal
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So that graphic shows a booster flip maneuver in order to thrust "back" and cancel out the velocity, but the flamey end at the beginning of the dotted line and the end of the dotted line are opposite with no intervening flip...
Yeah, I think we're back to "artistic license" by suggesting that the booster actually flies back towards the launch site but then, inexplicably, ends up landing farther away from the launch site. The reality is that it'll do essentially the same as a Falcon 9 booster (but without reentry burn), and you've seen a million of those.
Here's SpaceX's current graphic to describe a Falcon 9 flight. That's what they should have done for Starship, and just compressed it horizontally. They don't need to use all that room on the left for ascent and staging. They could get reentry of both booster and Starship into the available space.
Why no entry burn for booster?
Entry burn is to reduce the speed the craft hits the atmosphere
It will be similar to an F9 RTLS flight profile but without reentry burn - so the booster will fly back towards the launch site. If I remember correctly the target booster soft landing location for test flight 1 was around 25 miles from the launch site. This makes sense as SpaceX will be trying to make the test flights as close as possible to the final RTLS profile.
On F9, they light the engines to slow it down and shield it from entry heating. Super Heavy engine section and profile are designed to not need that assistance. Future planned shift of fuel and delta-v to second stage means even less entry heating for SH.
Falcon 9 stages at 100 km and 7400 km/h (2.0 km/s). Starship is expected to stage at 70 km and 5700 km/h (1.6 km/s). There may also be advantages of dimensions of the boosters, with the Starship booster having a higher ratio of width to height (it's fatter for its size). Mongo also reminds me that the Starship booster is made of stainless steel, not aluminum. It's a beast.
Yeah, stainless steel for the win. It can withstand much higher heating loads, and its cross section acts as a very effective air brake.
It's why no one ever considered using steel in modern times for a rocket, and why Elon did. If you're going to throw away the first stage, then steel is just heavier for no advantage. If you plan on reuse, then it is able to withstand much higher heating loads on re-entry which eliminates carrying extra propellant for a re-entry burn.
But perhaps the additional weight of heavier steel (compared to Aluminum) negates the advantage of not carrying extra fuel..?
I am sure SpaceX would have all the details, but the decision to use steel has one key disadvantage of higher weight and many advantages of which one of them is the savings on landing fuel. The other I guess is perhaps much lesser costs
Stainless steel is the winner for now. I think a big part of that is the fact that you can build stuff fast and cheap - and destroy them. Test articles. Flight prototypes. Anything you like. It's consistent with the ethic of moving fast and breaking things. Another big part of it is that current missions are almost completely focused on roundtrips to LEO. That means reentry, and that means thermal protection. Taken on the whole, stainless steel is a great choice. Slap some tiles on it and you're good to go for reentry.
Down the road, they'll have solved all the problems, figured out all the unknowns, and can switch from moving fast and breaking things to straight up optimization. That's when they may well go to aluminum. The one place where aluminum fails is reentry. So SpaceX may stick with stainless steel reentry Starships for a while, but they can build a lot of other stuff with aluminum. The boosters themselves may be able to switch over. HLS can be aluminum. A fuel depot. Plus other stuff like station segments, space tugs, etc.
I don't know enough about the material properties of aluminum to know if it's actually the material of choice for optimization. Its thermal cycling properties may make it completely inadequate. Perhaps they'll go back to the original plan of carbon fiber. You don't want to build experiments with it, but you can build your production articles out of it.
Given the thermal issues that led to SS, as you mention, it would be interesting to see if Titanium ever has a role. Although Al or composite neeeded enough thermal shielding to effectively cancel out the weight savings, titanium alloy might fit both requirements.
Expensive and hard to work with (the SR71 stories about this are enlightening), but might be one of the few materials that would meet the requirements.
Right. Or a dozen other materials, some of whose appropriateness may not be recognized until operations are fully underway in space. Fortunately, NASA has been doing some basic research on how materials hold up in the environment of low Earth orbit.
I guess they'll have to start working on the Materials Lunar Experiment, though even a bit of that has been done on an ad hoc basis.
Edit: Here's a PDF of the paper summarizing what NASA learned from examining the parts that they brought back from Surveyor 3.
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Road closure for the 13th, as of yet not listed as a flight, but that can change.
It's even better than that, I think. There are road closures scheduled for the 13th through the 15th. They either want to really get something done (like a launch) because there are backup dates, or they're doing something that's going to take three nights to do; the closures are between midnight and 2pm each day.
The optimist in me thinks that the timing is suggestive of an early-morning launch, which would keep the winds down.
No Temporary Flight Restrictions or Notices To Airmen (Air Missions). Well, there's the TFR for Boca Chica itself, but that's it.
And it appears that the FTS charges are being installed, which implies launch reasonably soon:
The notice to mariners regarding the exclusion zone has been modified from including 11/13&14 to starting 11/15. The road closures for those days have been cancelled too.
So it looks like we could be a go for flight as early as next Wed... although still no word on if the FAA requested environmental studies have been completed...
The notice to mariners regarding the exclusion zone has been modified from including 11/13&14 to starting 11/15. The road closures for those days have been cancelled too.
So it looks like we could be a go for flight as early as next Wed... although still no word on if the FAA requested environmental studies have been completed...
NSF livestream last night showed what should be the final re-stacking. Also, yesterday the FTS charges were installed (First photo below, shown between the two workers)
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