There have been 2 Musk TweetStorms this weekend, and he states tests by March-April, followed by a full tech briefing.
A custom 300 series stainless steel alloy. They’re building their own foundry and using external sources.
9m diameter, but shorter than Starship, Hopper being built/flown at Boca Chica, with a Mk 1 Starship being built in San Pedro. First Super Heavy will be full scale.
3 Raptors in Hopper, and it’s been redesigned. 100,000 hp pumps.
Polished skin, max reflectivity & far less shielding.
FCC application says the Hopper will fly to 5km. Perhaps the Mk 1 after that?
What a stunning number (at least to me). The size of these new rocket ships is difficult to visualize, mostly because they are viewed by the likes of me (Joe Public) through benefit of a very long telephoto lens.
Discuss would not let me upload an image, claiming that I wasn’t logged in (I was):
Stainless steel sounds like the old idea about “Big Dumb Rockets” (or for smaller ones, and as Mitch Clapp once put it, “Micro Moronic Rockets”.) Using easily produced and welded materials is very inexpensive. It’s mass inefficient, but there is a good case that the low cost outweighs the inefficiency. That might be the idea behind SpaceX using steel.
Steel is also easier to repair if something gets a hole punched in it. Laying up CF in Mars’ dusty, cold atmosphere doesn’t sound like fun, but with stainless steel you can apply a patch and use a portable welder. Zip-zap.
Apparently the idea is that steel (honeycomb panels, as used on the B-70?) with high surface reflectivity will allow it to tolerate entry heating better than carbon fiber panels of similar mass. Of course the RCC panels on the Shuttle could take a lot of heat, but they were relatively heavy for composite structures.
Steel is a _really_ good structural material. The only way aluminum and titanium alloys can outperform it in applications is via their low density. So if the piece already has to be X strong, steel can actually handle the loads with less mass, and much less volume. And if you bring heat into the equation (high structural loads under high thermal loads, AKA reentry), steel comes second only to some superalloys, way ahead of titanium, and carbon fiber melts and/or burns.
In other words, since this is a honking big thing that is going to be massive and has to handle relatively big structural and thermal loads, as long as you don’t have to make the walls so thin you have to go with pressure-stabilized balloon structures like the old Atlas, why the heck not steel.
It could even be said it is obvious in retrospective. I know I have speculated a lot that probably BFR can make do with metallic TPS due to the low ballistic coefficient. It’s all about engineering trades!
Which at the size of that monster, probably gave him a crazy good structural fraction, good enough to give any fancy Al-Li alloy modern EELV a run for its money. Size actually works in favor of rockets, theoretically speaking. Then are some real world limitations, of course… the size of Sea Dragon’s combustion chambers is what really made it impractical.
IIRC, Sea Dragon concept was even bigger. To be built in a shipyard, floated out to sea, fueled from tankers, and launched from the surface of the water. I worked for RCT at Aerojet’s Advanced Propulsion Dept., as a college student in the summer of 1962. Bet he’s smiling down from wherever he is! Ad Luna! Ad Ares! AD ASTRA!
The Atlas is pressure stabilized stainless steel, so thin you can indent it with your hand. But in the display area at Kennedy Space Center, where the salt air inevitably corrodes the aluminum rockets, the 50 year old Atlases still look new – and still hold pressure.
It is probably harder to work with composites then originally envision. The weight reduction is not an issue with the hopper version so they are building it out of easy to use steel. Work out the take off and landing systems and the rest will be easy.
BTW a similar path was followed with DC-X. The original tanks were made by Chicago Birdge and Iron. Then replaced by composite ones in the DC-XA.
Composites are good for structures that have few penetrations, simple shapes, and limited connections to other stuff. NASA was determined that the crew compartment for Orion be made out of composites. LockMart trade studies showed that aluminum alloys were better given the large number of penetrations, the loads, and the items that needed to be attached to the structure. NASA didn’t like the conclusion, so the trade was repeated several times. LM had experts from the fleet ballistic missile program, F-35, F-22, C-130 and other programs (all of which used composities) involved each time. That said, Orion does make extensive use of composites in other areas. Tankage, non-load bearing panels, etc. all had composite components.
Penetrations and load attachments are big bugaboos as you have to insert metallic fittings at all of them and build up the structure around them to accommodate them as I understand it. (I’m not a structures guy, but I was in meetings where the trades were presented to NASA.)
Your description of how NASA approached this issue, and their decision making process, is illuminating. I had already been thinking about how radical a change that SpaceX seems to be making took relatively little time, considering the news about their carbon fiber mandrel being purchased and used at Port of Los Angeles was not too long ago. Shows how a private company can turn on a dime (or a few million bucks more likley!) and pivot to a more logical solution in so little time. Time is money in this case, since I think Elon can see Jeff Bezos (with the New Glenn) in his rear view mirror coming ever closer!
Most famously on the X-33 where LM engineers concluded that the multilobed, semiconformal LH2 tank would be lighter if made of metal rather than composites, but were ordered to use the latter.
Boeing build the mandrels so stingers are laid in and bonded to the fuselage the same time the body is made. And tape laying machines automatically make built up area where penetrations or whatever will be. It ain’t the 60s.
That actually puts what SpaceX is trying to do into perspective. The 787 took eight years to develop, the program cost something like $30 billion, and the unit cost is around $200 million per aircraft. SpaceX is talking about developing and flying a spacecraft for less and doing so in shorter time.
They learned that composites are a bitch to work with, that steel has strength advantages, and that steel predictably behaves in high energy (heat) environments that are advantageous, among other things already discussed. At least that’s what the Pod World is saying.
They will cool the side of a ship facing the most heat on entry with liquid methane, presumably as it moves from storage to engines. I suppose, not really knowing, that this is well-understood technology analogous to nozzle cooling.
But it sounds like an engineer’s nightmare as well. The liquid fuel will be subjected to all sorts of heat regimes as it passes finally to the combustion chamber; and in each of these regimes the liquid/gas will affect the volume and local pressure of the material.
when I look at the Dragon and CST the artistic concept is totally different. Dragon with its curves and fins is straight out of “Astounding Stories”, CST is from “2001 A Space Odessy”.
Yeah exactly. That 1950 Robert Heinlein inspired (he was also the technical consultant) is science fiction that was already science. He made sure the movie stuck to the factual universe. A nuclear powered space ship built in the desert by private enterprise. It a somewhat Popular Mechanics science fiction but had more viability than many SF films that followed for a long while.
By the by Bob the other ship, on the right, is the space ship from When World Collide. Looks like an artist grabbed that and reframed it. Tho that may have been an art concept for the movie. However that ship was NOT in a desert. In the film looked more like the Santa Cruz mountains.
Many Robert Heinlein novels referenced a “captain of industry” or a “rich industrialist” that were building space ships. After Apollo, this was treated as so much fantasy, since it was established that only nations could afford to do space. And yet, here we are…
Apollo was actually the outlier with most innovation and progress coming from Captains of Industry. Arthur C. Clarke’s first novel of a rocket to the Moon also featured it as a private venture. Elon Musk and Jeff Bezos are just returning us to the historic path to Tomorrowland ?
Not just in the desert, but in the dirt. I’m figuring this is a proof of concept, unless it’s just a prop. But then a prop wouldn’t have obviously fixed landing legs. So, PoC prototype.
So if I’m reading the tea leaves right, it seems they have done their engineering trades for structural and thermal loads, and steel has been the victor (for the upper stage at least, I doubt the story is quite the same with the booster), hence the latest “delightfully counterintuitive” redesign. The other thing that’s settled down is Raptor, I imagine, since they have a long test campaign under their belts and should be producing full-size engines for the hopper.
This is all great and good, at least they can settle now their general performances (structural mass ratio+engine specs dominate final performance), but I must say, there are still A LOT of things to bolt on top of that to produce a CDR-worthy design.
Which is to say, I won’t trust any payload numbers for a good long while yet, since they have a heck of a lot of systems engineering and system integration design in front of them, and a lot of things could change. But the basic bones of the design have been laid, and it would be a very big setback to change them now. Personally, I must say like the shinies, and wish them the best of luck. It would be truly awesome to see this thing fly.
A highly reflective rocket that lands rear-end first on retro propulsion is straight out of a large number of the old scifi tales.
Heck, the annual SciFi Hugo Award is shiny and shaped pretty much like the BFS/Starship-upper-stage. The universal symbol of SciFi literature is a rocket, shaped very close to that…but with a more joint-shaped, streamlined look.
Elon couldn’t have picked more marketable optics to excite people to the next space race…or sell more of our SciFi literature for that matter. 😉 He deserves his own Hugo award for it. NASA would never have built a ship shaped like that.
I know the main space/starship is going to be skin with stainless steel but is he using stainless steel for the booster to? The main starship needs stainless steel to handle the heat of reentry but the booster does not need it.
At last! I now understand Donald Trump’s obsession with the wall – it isn’t a wall, the thing is obviously the launch track for the Starship. Everything makes perfect sense now! Obviously, he’s too important to escape on the first flight – he’ll have a VIP suite on the ‘B’ Ark… …simples!
It’ll be interesting to see what SpaceX’s engineers have found that have driven this change.
Hopefully what we’re looking will be doing test flights soon, much like Grasshopper did.
There have been 2 Musk TweetStorms this weekend, and he states tests by March-April, followed by a full tech briefing.
A custom 300 series stainless steel alloy. They’re building their own foundry and using external sources.
9m diameter, but shorter than Starship, Hopper being built/flown at Boca Chica, with a Mk 1 Starship being built in San Pedro. First Super Heavy will be full scale.
3 Raptors in Hopper, and it’s been redesigned. 100,000 hp pumps.
Polished skin, max reflectivity & far less shielding.
FCC application says the Hopper will fly to 5km. Perhaps the Mk 1 after that?
Nice, concise summary.
‘100,000 hp’.
What a stunning number (at least to me). The size of these new rocket ships is difficult to visualize, mostly because they are viewed by the likes of me (Joe Public) through benefit of a very long telephoto lens.
Discuss would not let me upload an image, claiming that I wasn’t logged in (I was):
https://www.teslarati.com/s…
It’s a ‘tank tooling tool’ that I found helpful.
Stainless steel sounds like the old idea about “Big Dumb Rockets” (or for smaller ones, and as Mitch Clapp once put it, “Micro Moronic Rockets”.) Using easily produced and welded materials is very inexpensive. It’s mass inefficient, but there is a good case that the low cost outweighs the inefficiency. That might be the idea behind SpaceX using steel.
Steel is also easier to repair if something gets a hole punched in it. Laying up CF in Mars’ dusty, cold atmosphere doesn’t sound like fun, but with stainless steel you can apply a patch and use a portable welder. Zip-zap.
In light of this weekend’s tweet storms I’m posting this from December 8th –
Super Heavy construction starts in spring.
https://twitter.com/elonmus…
Active cryocooling TPS ?
https://twitter.com/elonmus…
Apparently the idea is that steel (honeycomb panels, as used on the B-70?) with high surface reflectivity will allow it to tolerate entry heating better than carbon fiber panels of similar mass. Of course the RCC panels on the Shuttle could take a lot of heat, but they were relatively heavy for composite structures.
Steel is a _really_ good structural material. The only way aluminum and titanium alloys can outperform it in applications is via their low density. So if the piece already has to be X strong, steel can actually handle the loads with less mass, and much less volume. And if you bring heat into the equation (high structural loads under high thermal loads, AKA reentry), steel comes second only to some superalloys, way ahead of titanium, and carbon fiber melts and/or burns.
In other words, since this is a honking big thing that is going to be massive and has to handle relatively big structural and thermal loads, as long as you don’t have to make the walls so thin you have to go with pressure-stabilized balloon structures like the old Atlas, why the heck not steel.
It could even be said it is obvious in retrospective. I know I have speculated a lot that probably BFR can make do with metallic TPS due to the low ballistic coefficient. It’s all about engineering trades!
Yes, Bob Truax wanted to build the massive Sea Dragon out of steel at a shipyard.
Which at the size of that monster, probably gave him a crazy good structural fraction, good enough to give any fancy Al-Li alloy modern EELV a run for its money. Size actually works in favor of rockets, theoretically speaking. Then are some real world limitations, of course… the size of Sea Dragon’s combustion chambers is what really made it impractical.
IIRC, Sea Dragon concept was even bigger. To be built in a shipyard, floated out to sea, fueled from tankers, and launched from the surface of the water. I worked for RCT at Aerojet’s Advanced Propulsion Dept., as a college student in the summer of 1962. Bet he’s smiling down from wherever he is!
Ad Luna! Ad Ares! AD ASTRA!
The Atlas is pressure stabilized stainless steel, so thin you can indent it with your hand. But in the display area at Kennedy Space Center, where the salt air inevitably corrodes the aluminum rockets, the 50 year old Atlases still look new – and still hold pressure.
It is probably harder to work with composites then originally envision. The weight reduction is not an issue with the hopper version so they are building it out of easy to use steel. Work out the take off and landing systems and the rest will be easy.
BTW a similar path was followed with DC-X. The original tanks were made by Chicago Birdge and Iron. Then replaced by composite ones in the DC-XA.
Composites are good for structures that have few penetrations, simple shapes, and limited connections to other stuff. NASA was determined that the crew compartment for Orion be made out of composites. LockMart trade studies showed that aluminum alloys were better given the large number of penetrations, the loads, and the items that needed to be attached to the structure. NASA didn’t like the conclusion, so the trade was repeated several times. LM had experts from the fleet ballistic missile program, F-35, F-22, C-130 and other programs (all of which used composities) involved each time. That said, Orion does make extensive use of composites in other areas. Tankage, non-load bearing panels, etc. all had composite components.
Penetrations and load attachments are big bugaboos as you have to insert metallic fittings at all of them and build up the structure around them to accommodate them as I understand it. (I’m not a structures guy, but I was in meetings where the trades were presented to NASA.)
Your description of how NASA approached this issue, and their decision making process, is illuminating. I had already been thinking about how radical a change that SpaceX seems to be making took relatively little time, considering the news about their carbon fiber mandrel being purchased and used at Port of Los Angeles was not too long ago. Shows how a private company can turn on a dime (or a few million bucks more likley!) and pivot to a more logical solution in so little time. Time is money in this case, since I think Elon can see Jeff Bezos (with the New Glenn) in his rear view mirror coming ever closer!
Large companies are prone to the same group-think and management-by-inertia as NASA. SpaceX is unusual even for business and especially for aerospace.
(That said, I’m as horrified by these kinds of insider reports of manipulation of trade-studies as you are.)
Most famously on the X-33 where LM engineers concluded that the multilobed, semiconformal LH2 tank would be lighter if made of metal rather than composites, but were ordered to use the latter.
Boeing build the mandrels so stingers are laid in and bonded to the fuselage the same time the body is made. And tape laying machines automatically make built up area where penetrations or whatever will be. It ain’t the 60s.
I wonder how the 787 would be described in terms of penetrations, of which there are many?
That actually puts what SpaceX is trying to do into perspective. The 787 took eight years to develop, the program cost something like $30 billion, and the unit cost is around $200 million per aircraft. SpaceX is talking about developing and flying a spacecraft for less and doing so in shorter time.
They learned that composites are a bitch to work with, that steel has strength advantages, and that steel predictably behaves in high energy (heat) environments that are advantageous, among other things already discussed. At least that’s what the Pod World is saying.
They will cool the side of a ship facing the most heat on entry with liquid methane, presumably as it moves from storage to engines. I suppose, not really knowing, that this is well-understood technology analogous to nozzle cooling.
But it sounds like an engineer’s nightmare as well. The liquid fuel will be subjected to all sorts of heat regimes as it passes finally to the combustion chamber; and in each of these regimes the liquid/gas will affect the volume and local pressure of the material.
The SR-71 also used fuel to absorb some of the surface eating.
Reminds me of Destination Moon.
when I look at the Dragon and CST the artistic concept is totally different. Dragon with its curves and fins is straight out of “Astounding Stories”, CST is from “2001 A Space Odessy”.
Yeah exactly. That 1950 Robert Heinlein inspired (he was also the technical consultant) is science fiction that was already science. He made sure the movie stuck to the factual universe. A nuclear powered space ship built in the desert by private enterprise. It a somewhat Popular Mechanics science fiction but had more viability than many SF films that followed for a long while.
By the by Bob the other ship, on the right, is the space ship from When World Collide. Looks like an artist grabbed that and reframed it. Tho that may have been an art concept for the movie. However that ship was NOT in a desert. In the film looked more like the Santa Cruz mountains.
Ya, those wing rocket pods are a dead give-away. I recognized it immediately. I read both books the movie is based on as a teen, very enjoyable.
Funny when I first saw that picture, the first thing that popped into my mind was that they look more like props for a movie than flight hardware…
Many Robert Heinlein novels referenced a “captain of industry” or a “rich industrialist” that were building space ships. After Apollo, this was treated as so much fantasy, since it was established that only nations could afford to do space. And yet, here we are…
Apollo was actually the outlier with most innovation and progress coming from Captains of Industry. Arthur C. Clarke’s first novel of a rocket to the Moon also featured it as a private venture. Elon Musk and Jeff Bezos are just returning us to the historic path to Tomorrowland ?
Not just in the desert, but in the dirt.
I’m figuring this is a proof of concept, unless it’s just a prop.
But then a prop wouldn’t have obviously fixed landing legs. So, PoC prototype.
It’s on a concrete slab.
So if I’m reading the tea leaves right, it seems they have done their engineering trades for structural and thermal loads, and steel has been the victor (for the upper stage at least, I doubt the story is quite the same with the booster), hence the latest “delightfully counterintuitive” redesign. The other thing that’s settled down is Raptor, I imagine, since they have a long test campaign under their belts and should be producing full-size engines for the hopper.
This is all great and good, at least they can settle now their general performances (structural mass ratio+engine specs dominate final performance), but I must say, there are still A LOT of things to bolt on top of that to produce a CDR-worthy design.
Which is to say, I won’t trust any payload numbers for a good long while yet, since they have a heck of a lot of systems engineering and system integration design in front of them, and a lot of things could change. But the basic bones of the design have been laid, and it would be a very big setback to change them now. Personally, I must say like the shinies, and wish them the best of luck. It would be truly awesome to see this thing fly.
A highly reflective rocket that lands rear-end first on retro propulsion is straight out of a large number of the old scifi tales.
Heck, the annual SciFi Hugo Award is shiny and shaped pretty much like the BFS/Starship-upper-stage. The universal symbol of SciFi literature is a rocket, shaped very close to that…but with a more joint-shaped, streamlined look.
Elon couldn’t have picked more marketable optics to excite people to the next space race…or sell more of our SciFi literature for that matter. 😉 He deserves his own Hugo award for it. NASA would never have built a ship shaped like that.
I know the main space/starship is going to be skin with stainless steel but is he using stainless steel for the booster to?
The main starship needs stainless steel to handle the heat of reentry but the booster does not need it.
The Ori on Stargate also built large spaceships in the desert…
https://uploads.disquscdn.c…
…but the design and purpose were somewhat different. 😉
At last! I now understand Donald Trump’s obsession with the wall – it isn’t a wall, the thing is obviously the launch track for the Starship. Everything makes perfect sense now! Obviously, he’s too important to escape on the first flight – he’ll have a VIP suite on the ‘B’ Ark… …simples!
Here is the equilvalent from “Destination Moon”. Both panitings were done by the pioneer space artist Chesley Bonestell
https://www.imdb.com/title/…
But his image of the Destination Moon rocket on the Moon really does recall the image of the Starship on its surface.
https://www.imdb.com/title/…
Reminds me of a pathfinder mockup used to check clearances at the launch site, or just a big water tank to draw attention to SpaceX…………