Author Topic: BO vs SpaceX - development methods  (Read 14932 times)

Offline JamesH

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BO vs SpaceX - development methods
« on: 01/25/2016 09:46 AM »
There is a discussion on the arocket mail list on the difference between SpaceX approach to reusability and Blue Origins.

It comes down to SpaceX starting with expendable rockets and adding reusability, v s BO's completely clean sheet design.

There are a few people who think BO will be (much) more successful than SpaceX at reusability, because of this clean sheet design, and that because Bezo's has so much more money at his disposal he can afford this clean sheet approach.

My own ponderings on the matter are : Will BO design start to move toward SpaceX as they scale up? Or the other way round - will SpaceX designs move towards BO? How much of an advantage does a clean sheet give you? Both companies have to deal with the same law's of physics, will convergent evolution mean they end up with similar craft? Have SpaceX got a big enough lead that even a clean sheet approach will not enable BO to catch them up, since SpaceX have shown themselves to be very adaptable.

I'm not sure many of the above questions are answerable just yet. Whichever comes out on top, it's all quite exciting!

As a corollary, what would people here think would be a good 'clean sheet design'
« Last Edit: 01/25/2016 09:48 AM by JamesH »

Online rpapo

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Re: BO vs SpaceX - development methods
« Reply #1 on: 01/25/2016 10:18 AM »
It is a clean sheet design, but with very different constraints on it, with the biggest difference (IMHO) being in the mass budget for the recovery hardware and for providing greater safety margins.   The different constraints by necessity result in different designs.

That said, whatever SpaceX may say, the Falcon remains an expendable rocket to which recovery provisions have been added.  That's not a bad thing: because it was designed that way it was able to get to work and bring in revenue at once, allowing them to work on recovery as a post-rollout, ongoing experiment.
« Last Edit: 01/25/2016 10:38 AM by rpapo »
An Apollo fanboy . . . fifty years ago.

Offline Jarnis

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Re: BO vs SpaceX - development methods
« Reply #2 on: 01/25/2016 11:08 AM »
I would venture a guess that F9 v1.1 is much more "clean sheet design" than you probably think.

They didn't just bolt on some legs to a F9 v1.0. Plenty of other changes were added.

Besides, SpaceX has always aimed for re-use - but instead of spending years and years just working on it, they spent that time launching stuff while working out the kinks. Iterative design.

I'm far more interest in seeing how the BO design will differ due to not being constrained by the requirement of having the booster road-transportable as their factory will be right next to the pad.


Offline Dante80

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Re: BO vs SpaceX - development methods
« Reply #3 on: 01/25/2016 11:46 AM »
The one approach is top-down, the other bottom-up. And both approaches have interesting challenges.

For example. Our current best guess with the info that we have available is that the New Shepard stage is really built like a tank (judging from the video data analysis we have, as well as the announced specs for the BE-3 engine). It can really afford to do so too, since the fuel mass fraction does not need to be very high for a straight up sub-orbital flight. And this really makes sense, since the goal for Blue is to be able to launch customers as fast as possible to make a market out of this.

Making a re-usable first stage for an orbital rocket though..is really a different beast. Your fuel mass fraction has to be very aggressive, as well as your stage TWR - for the simple fact that you need a bigger second stage to do most of the work of getting to orbit. This also means that you need to throttle A LOT to do a propulsive landing, like the SpaceX and Blue architectures are designed for. For reference, Falcon 9 throttles down to around 6-7% in the final landing burn, and still has to do a hover-slam instead of a soft hover landing like New Shepard (since the fuel mass fraction for the stage is apparently way above 0.93).

So margins have to be a lot stricter, and a lot more things can go wrong, or turn expensive (when you have to service the hardware afterwards). This is the big bet that both Blue and SpaceX must win, and none of them has managed that so far.

Which is why I'm really intrigued to see what architecture Blue is going to follow in their orbital rocket project (now 3 years into development). Just scaling the New Shepard won't do. Cheers...C:
« Last Edit: 01/25/2016 11:46 AM by Dante80 »

Offline kevinof

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Re: BO vs SpaceX - development methods
« Reply #4 on: 01/25/2016 12:07 PM »
BO can't change the laws of physics.

BO's New Shepard is small, agile, weighs (probably) very little, goes straight up, and back down again.  If they are to make an orbital stage that is capable of putting a reasonable payload into orbit then they will face exactly the same issues as Space X, ULA and everyone else. They will have to manage fuel margins, control issues (they haven't even scratched that yet), strut breakages, engine out scenarios, stability of a large stage coming in at speed, heating control, and everything else that Space X is and has encountered.

BO are only starting out on this adventure and while they have a nice (and probably the most potential) in a sub-orbital vehicle, there's a huge difference to taking the step to orbital stages, never mind orbital re-usable stages.

Space X started with a clean sheet. Their plan was always to re-use and that means return and land, and that means legs. They didn't just decide to stick them on as an afterthought. They didn't design them on the back of a napkin and say "this will do". We've all seen that Space X have smart engineers and solve problems and this was their engineering solution based on the data they have.

I'm not a betting man but I'll put $10 down that whenever BO/ULA or whoever build a re-usable orbital stage it will have many of the design and engineering decisions that we see in the Space X Falcon 9.

There is no magic sauce here. 

Offline JamesH

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Re: BO vs SpaceX - development methods
« Reply #5 on: 01/25/2016 12:48 PM »
BO can't change the laws of physics.

BO's New Shepard is small, agile, weighs (probably) very little, goes straight up, and back down again.  If they are to make an orbital stage that is capable of putting a reasonable payload into orbit then they will face exactly the same issues as Space X, ULA and everyone else. They will have to manage fuel margins, control issues (they haven't even scratched that yet), strut breakages, engine out scenarios, stability of a large stage coming in at speed, heating control, and everything else that Space X is and has encountered.

BO are only starting out on this adventure and while they have a nice (and probably the most potential) in a sub-orbital vehicle, there's a huge difference to taking the step to orbital stages, never mind orbital re-usable stages.

Space X started with a clean sheet. Their plan was always to re-use and that means return and land, and that means legs. They didn't just decide to stick them on as an afterthought. They didn't design them on the back of a napkin and say "this will do". We've all seen that Space X have smart engineers and solve problems and this was their engineering solution based on the data they have.

I'm not a betting man but I'll put $10 down that whenever BO/ULA or whoever build a re-usable orbital stage it will have many of the design and engineering decisions that we see in the Space X Falcon 9.

There is no magic sauce here.

I guess the magic source is at the root of my original question. Given a completely clean sheet, will BO end up with something very different from F9 due to magic sauce,. or something very similar due to lack of magic sauce.

I do like their fin arrangement at the top, I would expect that that can replace grid fins. But that is not a huge difference.

Offline Garrett

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Re: BO vs SpaceX - development methods
« Reply #6 on: 01/25/2016 01:06 PM »
Their plan was always to re-use and that means return and land, and that means legs. They didn't just decide to stick them on as an afterthought.
It was an afterthought. Look at the Falcon 9 - it's a regular looking rocket with legs stuck on the side.
Reuse was always their goal, but how exactly to achieve that goal was never set in stone. It still isn't.

The Merlin engines, on the other hand, were designed from the start to be reuseable.
- "Nothing shocks me. I'm a scientist." - Indiana Jones

Offline Kabloona

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Re: BO vs SpaceX - development methods
« Reply #7 on: 01/25/2016 01:28 PM »
It was an afterthought. Look at the Falcon 9 - it's a regular looking rocket with legs stuck on the side.

That's like saying tree branches were afterthoughts in the design of trees because they're stuck on the sides.

Offline sanman

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Re: BO vs SpaceX - development methods
« Reply #8 on: 01/25/2016 02:20 PM »
Airliners generally look alike, and so do submarines, because the laws of physics dictate their own optimal solutions.
These days a lot of SUVs are starting to look alike, too.

Furthermore, I'd imagine that when Blue engineers are looking for solutions, they'll be tempted to turn towards the ones already achieved by SpaceX.

But given that Blue's engine and fuel choices are very different from SpaceX's, these differences will surely result in significant differences for the overall vehicle.

What kinds of unique features from Blue's suborbital vehicle are likely to make it into their orbital rocket?
Will that ring-fin thing be there? And the drag brakes?

How likely is it that their orbital rocket will look just like this concept image?





Online edkyle99

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Re: BO vs SpaceX - development methods
« Reply #9 on: 01/25/2016 02:41 PM »
It was an afterthought. Look at the Falcon 9 - it's a regular looking rocket with legs stuck on the side.

That's like saying tree branches were afterthoughts in the design of trees because they're stuck on the sides.
SpaceX planned parachute recovery for the early Falcon 9 first stages (they even had a parachute contractor http://www.airborne-sys.com/pages/view/spacex-falcon-1-and-falcon-9 ) , so it seems that SpaceX didn't plan VTVL from the very start.

For me, the major difference between the two companies is their propulsion choices.  SpaceX uses all kerosene fuel and similar engines on both stages (in terms of the turbopump hardware at least).  Blue is methane and hydrogen and higher thrust first stage engines and more specialized engines on each stage.

 - Ed Kyle
« Last Edit: 01/25/2016 02:48 PM by edkyle99 »

Offline sanman

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Re: BO vs SpaceX - development methods
« Reply #10 on: 01/25/2016 03:16 PM »
Musk seems to broadcast his intentions ahead of time, so had he been thinking about reusability back in the Falcon-1 days he probably would have said so very publicly.

What I remember was that he announced the idea of powered landing for Dragon shortly after Boeing announced its CST-100 would use a pusher design for launch abort. I don't know if that's what inspired him, but I recall his announcement of thrusters on Dragon came soon after the CST-100 announcement.

Offline kevinof

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Re: BO vs SpaceX - development methods
« Reply #11 on: 01/25/2016 03:23 PM »
Musk was talking about reusability for years before dragon? Original aim was for both S1  and S2  to be returned.

Offline Lars-J

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Re: BO vs SpaceX - development methods
« Reply #12 on: 01/25/2016 03:49 PM »
I do like their fin arrangement at the top, I would expect that that can replace grid fins. But that is not a huge difference.

Really? To me the New Shepard fins on the top are the most hack-ish and inelegant part of the design. This is what I expect to change the most for an orbital launcher, as this will really make the interstage structure a challenge if you are going to have a real 2nd stage and payload massing 100+ tons on top of it.

Grid fins are IMO the most elegant and ingenious part of F9 - wraps perfectly around cylinder shape, and provides all the glide control the stage needs for *very little* mass and few moving parts.

I fully expect Blue's orbital LV booster to have fins more in line with F9 rather than a giant ring fin structure with lots of moving parts.
« Last Edit: 01/25/2016 03:50 PM by Lars-J »

Offline nadreck

Re: BO vs SpaceX - development methods
« Reply #13 on: 01/25/2016 03:52 PM »
Both companies wanted reuse from their inception. In that respect both were starting from clean sheets.

However, SpaceX went the route of saying while we are aiming for reuse, we will be building and flying orbital rockets for pay while testing the systems we believe can support reuse. Their process was to try and discard systems or refine the reuse potential of each system.

Another major difference is that BO started by developing and refining a single stage sub orbital craft and booster while the SpaceX first cut was an orbital design. Shep will never be an orbital 2nd stage with the current engine and lack of TPS. It must have a new vacuum version of the engine, it must have a re-entry system added. Whether or not the first orbital vehicle's upper stage resembles the Sheppard is a big question, but for sure the engineering effort to allow it or something else to perform what SpaceX has given up on with their current S2 has not been demonstrated.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline Stan-1967

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Re: BO vs SpaceX - development methods
« Reply #14 on: 01/25/2016 05:11 PM »

I guess the magic source is at the root of my original question. Given a completely clean sheet, will BO end up with something very different from F9 due to magic sauce,. or something very similar due to lack of magic sauce.

I do like their fin arrangement at the top, I would expect that that can replace grid fins. But that is not a huge difference.

I think for a first stage VTVL re-use scheme, design commonality will converge to F9 style choices.   New Shepard is a nicely optimized sub-orbital configuration that does not fully scale to a multi-stage rocket.   The "interstage section" of New Shepard, ( separating the rocket from the capsule) which contains the deployable fins and air brakes will not necessarily scale well for a first stage that has a S2 with a sizable vacuum nozzle utilizing the interstage volume. 

As mentioned already, there is no magic sauce, just design choices dictated by the weight constraints and control authority needed to get the acceptable cross range to precision landing capability.  When I make a list o differences and equivalents, it's pretty clear each is solving problems specific to the different flight conditions where choices differ, and where choices are the same ( or close) is because they are solving the same problem.
 
1. New Shepard has bottom fins ( for roll control?) vs. F9's 9 engines with TVC
2. F9 has vacuum restartable engines for boost back, no such capability on New Shepard, as it is not needed.
3. F9 has cold gas thrusters for vacuum  & atmospheric attitude control, New Shepard probably has equivalent.
4. F9 has restartable engines for supersonic retropropulsion, New Shepard does not, nor does it need it.
5. Both New Shepard and F9 have a final retro-burn for landing, with New Shepard having a greater T/W range.
6. Both deploy their landing legs at the last minute, and the differences are more stylistic vs. functional. ( insectoid vs. blossoming flower  :o)
7. F9 deploys grid fins in a supersonic flight regime, shifting CP aft for greater crossrange control & precision, New Shepard deploys fins that are stored in the "interstage" space.  From a control standpoint, why duplicate the fins on the bottom?  I think it is to move the CP aft, just like on F9, & for the same reasons.

A better question than debating it's comparability to the F9 first stage would be to ask if New Shepard scalable as a re-usable second stage?  Anyone with experience think air brakes and fins are good choices for the re-entry profile of an orbital second stage?  Or just a good clean sheet design for sub-orbital?   What would have to change on New Shepard to make it a reusable second stage?

Offline Elmar Moelzer

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Re: BO vs SpaceX - development methods
« Reply #15 on: 01/26/2016 12:53 AM »
To me it is rather simple.

SpaceX: established in 2002, first paid launch in 2010 (?) and that launch was to orbit, already is making profit.
Reusable orbital first stage.

Blue Origin: established 2000 (has it really been that long already?) and has yet to have a paid launch. Reusable suborbital(!) launch vehicle. No profit yet and probably not for several years.

Looking at it from a business POV, SpaceX is clearly ahead. Technically too, IMHO.

Offline ey

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Re: BO vs SpaceX - development methods
« Reply #16 on: 01/26/2016 06:49 AM »
The Blue Origin approach so far seems to be to design and test everything in a lab, and infrequently do test flights in relative secrecy. They don't have to set up and maintain a factory like SpaceX does since they only have one vehicle, but they also have no revenue and only limited flight experience so far to validate their designs.

It's possible that their plan is to skip over building a commercial medium lift rocket (leaving that to ULA Vulcan), and go straight to a BFR-style super heavy reusable booster where mass fraction is less important because it's overkill for most payloads. The high cost would be mitigated by only having to build one of them. But it's also quite risky because any failed flight or return, even for the prototypes, would be extremely expensive. They would have to be extremely confident that they have their design and manufacturing processes down pat.

Possibly in between they'd introduce a smaller reusable orbital rocket capable of launching very light payloads (OneWeb) to LEO, probably not profitable but would give them practical experience launching orbital payloads.

Offline fvandrog

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Re: BO vs SpaceX - development methods
« Reply #17 on: 01/26/2016 02:08 PM »

SpaceX: established in 2002, first paid launch in 2010 (?) and that launch was to orbit, already is making profit.
Reusable orbital first stage.


That's interesting. Do you have official numbers backing up the claim about profitability?

Offline Jet Black

Re: BO vs SpaceX - development methods
« Reply #18 on: 01/26/2016 03:36 PM »

SpaceX: established in 2002, first paid launch in 2010 (?) and that launch was to orbit, already is making profit.
Reusable orbital first stage.


That's interesting. Do you have official numbers backing up the claim about profitability?

They say they are

http://www.spacex.com/about
For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled. -- Richard Feynman

Offline sanman

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Re: BO vs SpaceX - development methods
« Reply #19 on: 01/26/2016 03:42 PM »
I too am inclined to think Bezos would go for a BFR type of rocket, skipping any Falcon Heavy iteration.

But both SpaceX and Blue have to stay on the Yellow Brick Road of where the money is. Neither can afford to go gallavanting towards the Moon or Mars while ignoring the bread-and-butter issue of revenues. Both companies will have to bow to the market demands of paying customers in order to stay in business. They will be forced to go where the market tells them to go, and can only deviate from that at their own peril. If one of them falters by sticking to a holy crusade at the cost of becoming sub-optimal for customers, then the other rival will swoop in and steal their lunch. (Heinlein's famous "TANSTAAFL" favorite quote comes to mind.)

But I'm wondering whether Bezos' bet on prioritizing the space tourist is a riskier-but-more-rewarding bet than Musk's reliance on serving NASA and satellite operators?
Musk's current customer base is safer, but satellite operators don't care about going to the Moon or Mars. Meanwhile, Musk's relationship with NASA also makes him hostage to the US Congress in a way that Bezos wouldn't be.

Are we going to see a Tortoise-and-Hare situation, whereby the late starter Blue Origin is able to outpace SpaceX in the long run, because it prioritized space tourists first?


--


Anyway, Blue's gone for developing reusability before orbital capability, while SpaceX has gone the other way for orbital capability before reusability.

People are saying that SpaceX's contract to develop Raptor will result in a more robust and capable engine than BE-4. But there's no reason why Blue couldn't evolve BE-4 further, or develop a BE-5 that does FFSC.


« Last Edit: 01/26/2016 03:45 PM by sanman »

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