Starship IFT-3: Pi Day!

[brentius]

So, SpaceX just released the launch date for IFT-3 (14/3).



Stream starts at 7, and the NOTMAR ends at 11. Excitement guaranteed!

 

[brentius]

 

[NTP2]

Anyone want to place bets on working?

Ps I think it will, last time they got most of the way, just a few more minutes.

 

[brentius]

Anyone want to place bets on working?

Ps I think it will, last time they got most of the way, just a few more minutes.

My guess is S28 makes orbit but burns up on reentry, while Super Heavy impacts the sea and gets destroyed.

 

[NTP2]

My guess is S28 makes orbit but burns up on reentry, while Super Heavy impacts the sea and gets destroyed.

that’s my assessment except for reentry as it’s passive, as long as the tiles are all still attached it’ll be fine.

 

[brentius]

that’s my assessment except for reentry as it’s passive, as long as the tiles are all still attached it’ll be fine.

Yeah, Flight 3 will probably make it.

 

[ThirstyBarbarian]

I think Starship will probably make orbit. That’s what I’m most confident of.

And I think Superheavy is likely to “land” successfully in the ocean as planned, but I’m not as confident in that. It really depends on how reliably the Falcon 9 booster techniques scale up. It probably has a good chance.

The reentry has never been tested, so hopefully it works, but I’m not really sure what to expect. It’s bigger and heavier than the Space Shuttle was. Is this going to be the largest thing every to attempt a controlled reentry? Anyway, I’m less confident in this part. Assuming it makes it through reentry, I think it has a good chance of making a successful water “landing”.

If it completes all those tests, then I suggest celebrating with a pi day pie. It’s probably good Musk didn’t schedule this for 4/20, like he likes to do, because the celebration means a lost afternoon. Go with the pie.

 

[NTP2]

I think Starship will probably make orbit. That’s what I’m most confident of.

And I think Superheavy is likely to “land” successfully in the ocean as planned, but I’m not as confident in that. It really depends on how reliably the Falcon 9 booster techniques scale up. It probably has a good chance.

The reentry has never been tested, so hopefully it works, but I’m not really sure what to expect. It’s bigger and heavier than the Space Shuttle was. Is this going to be the largest thing every to attempt a controlled reentry? Anyway, I’m less confident in this part. Assuming it makes it through reentry, I think it has a good chance of making a successful water “landing”.

If it completes all those tests, then I suggest celebrating with a pi day pie. It’s probably good Musk didn’t schedule this for 4/20, like he likes to do, because the celebration means a lost afternoon. Go with the pie.

If anything being bigger makes it easier as surface area scales quicker than volume so you have less demand from each tile and a larger thermal mass.

 

[ThirstyBarbarian]

If anything being bigger makes it easier as surface area scales quicker than volume so you have less demand from each tile and a larger thermal mass.

That may be true that the surface area may work to its advantage. But it’s also likely more massive, so there’s more energy that needs to be dissipated.

 

[NTP2]

That may be true that the surface area may work to its advantage. But it’s also likely more massive, so there’s more energy that needs to be dissipated.

Well I agreed until I did the math, it turned out that space shuttle had a larger dry mass.

 

[ThirstyBarbarian]

Well I agreed until I did the math, it turned out that space shuttle had a larger dry mass.View attachment 634324

Interesting! I would not have guessed that. I thought a lot of the space shuttle was made of relatively lightweight materials compared to starship made of stainless steel.

I guess we will just have to wait and see what happens. It’s only a week away now. Should be exciting!

 

[brentius]

Interesting! I would not have guessed that. I thought a lot of the space shuttle was made of relatively lightweight materials compared to starship made of stainless steel.

I guess we will just have to wait and see what happens. It’s only a week away now. Should be exciting!

Excitement Guaranteed!

 

[techrat]

I thought a lot of the space shuttle was made of relatively lightweight materials compared to starship made of stainless steel.

The shuttle had a lot going on in it, not the least of which was a life-support system to keep 7 astronauts alive. There was a robotic arm, a lot of 1980's era computers, landing gear and a bunch of dead weight, like the main engines. The shuttle was mostly aluminum, but I'm wondering how think it needed to be versus the Starship's stainless, which as MUCH more strength, and therefore, might be thinner, leading to (ironically) less weight than the shuttle.

 

[brentius]

The shuttle had a lot going on in it, not the least of which was a life-support system to keep 7 astronauts alive. There was a robotic arm, a lot of 1980's era computers, landing gear and a bunch of dead weight, like the main engines. The shuttle was mostly aluminum, but I'm wondering how think it needed to be versus the Starship's stainless, which as MUCH more strength, and therefore, might be thinner, leading to (ironically) less weight than the shuttle.

Thing is, my guess is that starship's reentry profile is much steeper than the Shuttle's, as it's not a lifting body- SpaceX can't glide the thing down to the ocean.

 

[techrat]

I think Starship will probably make orbit. That’s what I’m most confident of.

Agreed. Starship was 3000kph from achieving target velocity when it suffered it's mishap last time. If they are coming down in the Indian ocean this time, they don't need to go as fast or as high this time as well, so, they can get to 25,000kph or so to achieve target velocity. That seems easy given what we know about IFT-2. Basically, if all 33 raptors light this time as well, they should have no issues with Starship -- the booster's "flip" is the only unknown at this stage (pun intended), and I believe the folks at SpaceX are smart enough to have worked this all out this time around.

Whether the Booster lands intact is a great unknown, but I'm not worried either way. For IFT-3 to work and be "successful" THE ONLY THING THAT'S IMPORTANT IS THAT STARSHIP ITSELF MAKES IT TO ITS DESTINATION. SpaceX can afford to blow up boosters for the next 5 years, as long as the payloads get to orbit.

 

[NTP2]

The shuttle had a lot going on in it, not the least of which was a life-support system to keep 7 astronauts alive. There was a robotic arm, a lot of 1980's era computers, landing gear and a bunch of dead weight, like the main engines. The shuttle was mostly aluminum, but I'm wondering how think it needed to be versus the Starship's stainless, which as MUCH more strength, and therefore, might be thinner, leading to (ironically) less weight than the shuttle.

That does make sense, I should note that I was using Elons number of 80 tons so it should be taken with a grain of salt.

 

[brentius]

Agreed. Starship was 3000kph from achieving target velocity when it suffered it's mishap last time. If they are coming down in the Indian ocean this time, they don't need to go as fast or as high this time as well, so, they can get to 25,000kph or so to achieve target velocity. That seems easy given what we know about IFT-2. Basically, if all 33 raptors light this time as well, they should have no issues with Starship -- the booster's "flip" is the only unknown at this stage (pun intended), and I believe the folks at SpaceX are smart enough to have worked this all out this time around.

Whether the Booster lands intact is a great unknown, but I'm not worried either way. For IFT-3 to work and be "successful" THE ONLY THING THAT'S IMPORTANT IS THAT STARSHIP ITSELF MAKES IT TO ITS DESTINATION. SpaceX can afford to blow up boosters for the next 5 years, as long as the payloads get to orbit.

My guess is the booster doesn't land, but Starship does.

 

[NTP2]

Thing is, my guess is that starship's reentry profile is much steeper than the Shuttle's, as it's not a lifting body- SpaceX can't glide the thing down to the ocean.

Actually I think it can glide a little, not gracefully but nether could the shuttle.

 

[brentius]

Actually I think it can glide a little, not gracefully but nether could the shuttle.

Well the fins are there for a reason, but it's no lifting body.

 

[cvanc]

My prediction is "it's all about how may tiles fall off".

Not too many = full success
Too many = Ship breakup on re-entry

 

[brentius]

My prediction is "it's all about how may tiles fall off".

Not too may = full success
Too many = Ship breakup on re-entry

Or, S28 makes it through the atmosphere but smashes into the Indian Ocean.

Still a success though.

 

[NTP2]

Well the fins are there for a reason, but it's no lifting body.

True it probably flys like a blue whale.

My prediction is "it's all about how may tiles fall off".

Not too may = full success
Too many = Ship breakup on re-entry

Why do you think they will come off?

 

[brentius]

True it probably flys like a blue whale.

Why do you think they will come off?

SpaceX had to replace a few thermal tiles on Ship 28, that's what they destacked it for (along with arming the FTS)

 

[techrat]

Actually I think it can glide a little, not gracefully but nether could the shuttle.

Truthfully, Starship and the Shuttle can glide about the same amount -- although the Starship would probably need a higher angle of attack to maintain that "glide" profile (which probably explain the canards). Both fly like a brick with some control surfaces.

If you've ever launched model rockets (wtf am I talking about, this is TRF after all), and had the nose cone pop, but the parachute doesn't deploy, and you've watched it come down sideways, you'll notice it still takes a LONG time for it to fall from 1000+ feet with that much air resistance. Contrary to what the Borg say, resistance isn't futile. It can save your rocket from destruction when falling onto grass. Most of the time, I don't even get a broken fin when it falls sideways.

Anyhow, that's kind of Starship works, but obviously, they have a bit more control.

 

[ThirstyBarbarian]

I think the fins on Starship were once described as being like the hands and feet of a skydiver. They can help control the fall and steer a bit, but they aren’t for lift. Starship comes in like a skydiver, not a glider.

 

[NTP2]

Truthfully, Starship and the Shuttle can glide about the same amount -- although the Starship would probably need a higher angle of attack to maintain that "glide" profile (which probably explain the canards). Both fly like a brick with some control surfaces.

If you've ever launched model rockets (wtf am I talking about, this is TRF after all), and had the nose cone pop, but the parachute doesn't deploy, and you've watched it come down sideways, you'll notice it still takes a LONG time for it to fall from 1000+ feet with that much air resistance. Contrary to what the Borg say, resistance isn't futile. It can save your rocket from destruction when falling onto grass. Most of the time, I don't even get a broken fin when it falls sideways.

Anyhow, that's kind of Starship works, but obviously, they have a bit more control.

I’ve never had it do that, I haven’t had the nose come off without the parachute.

 

[brentius]

Truthfully, Starship and the Shuttle can glide about the same amount -- although the Starship would probably need a higher angle of attack to maintain that "glide" profile (which probably explain the canards). Both fly like a brick with some control surfaces.

If you've ever launched model rockets (wtf am I talking about, this is TRF after all), and had the nose cone pop, but the parachute doesn't deploy, and you've watched it come down sideways, you'll notice it still takes a LONG time for it to fall from 1000+ feet with that much air resistance. Contrary to what the Borg say, resistance isn't futile. It can save your rocket from destruction when falling onto grass. Most of the time, I don't even get a broken fin when it falls sideways.

Anyhow, that's kind of Starship works, but obviously, they have a bit more control.

Yep, was almost killed when one of my friends' LPRs did just that and landed 2 meters from me.

 

[brentius]

From then on, I tie the parachute to a loop around the shock cord so the NC tugs it out.

 

[NTP2]

From then on, I tie the parachute to a loop around the shock cord so the NC tugs it out.

That is why it’s never happened to me.

 

[Aeva]

that’s my assessment except for reentry as it’s passive, as long as the tiles are all still attached it’ll be fine.

They’re still working on tile retention. Chances are a lot of tiles will be lost, but its hard to say if that’s enough to cause a failure during reentry. The space shuttles lost tiles all the time and still made it back fine. The exception, Columbia, was caused by damage to the hull of a wing. I don’t see that happening on starship since it doesn’t have that foam insulation or some other material to fall off and it’s arranged so that the reentry vehicle is above booster and tank rather than laterally adjacent to it.

I think it’s more likely we’ll see it self destruct like IFT 2, but later in the flight this time. E: read somewhere they were trying to do a vacuum start, and thought it was part of the reentry… i think i read wrong whoops.... E2: or maybe I was right? https://starship-spacex.fandom.com/wiki/Starship_Flight_Test_3 "objectives [...] the first ever re-light of a Raptor engine while in space". If anything goes wrong, I think it'd be here since that engine is one of the more complicated components that can fail if damaged.