Engineers blame 'intentionally conservative' test parameters for premature end to Space Launch System hotfire After the weekend's shorter-than-hoped-for test firing of the core stage of NASA's monstrous Space Launch System (SLS) rocket, engineers have confirmed the hardware remains in "excellent condition" and blamed "test parameters that were intentionally conservative." The parameters were designed for ground testing and were …
I'm not so sure - and that may be the reason that Space X and Blue Origin to a lessor extent are moving much faster than Boeing. They leave it to fail and gather more information.
In this test Boeing stopped it at the first sign of trouble - no doubt to try and protect a politically imposed launch date - but now have no idea if the problem would stabilize or get worse and cause a catastrophic failure and when. Space X would just let the bastard blow up and thus characterize the whole thing.Yeah it ain't cheap - but when you have stuff rolling off an assembly line instead of hand crafted by a cost plus band of artisans then it's a quick turnaround and another learning experience.
SLS has effectively been in development since 2005 (if you include the Constellation program) - only 3 years less than Space X has been in existence. Not only that they even had the engines 'gifted' to them so they didn't have to develop them. Since 2011 the development costs for the first stage booster alone are running at somewhere north of $20B and all they have to show for it are some politicians getting fat bribes. For reference Space X developed the Falcon 1 and 9 for around $400M.
You misunderstand. The purpose of NASA is pork - i.e. to spend money in lots of political districts so politicians can say how good they are at creating and/or keeping jobs. The short-term purpose of SpaceX is to build a successful, cheap, profitable rocket launching business, including unmanned and manned launches, as a stepping-stone to their longer-term goal of establishing a colony on Mars.
Both organizations are being very successful at achieving their goals. They're just completely different goals.
(Edit to add: I know there are lots of really smart people working at NASA who genuinely believe in advancing scientific knowledge and/or sending humans to explore. However, their mission and budget are set by politicians, and they set the goals of NASA to align with their desires for pork).
I think the thing you described happened well over 50 years ago, it was one of the reasons that LBJ was so keen on NASA and the space program after becoming president and why so much of it was based in Texas.
He certainly wanted to make use of the astronaut's families for PR purposes but they found that the astronauts and their wives were less compliant than hoped.
I worked at NASA years ago and the then old timers would love to reminisce about how the energetic moon flight days were the true NASA. They felt what other comments here are saying... that NASA has become a political football instead of an agency to advance science with a goal to keep America a world leader in technology. I am losing faith that America will continue to lead the world in technology for much longer.
If they did, they would be wrong, because the original purpose of NASA was cold war propaganda. You will recall that the Soviets had launched Sputnik. It was not at random that the Saturn V was chosen for the launch vehicle. It was also the launch vehicle for our ICBMs. My understanding is that Kennedy's science advisor agreed to support NASA on the condition that it was NOT to be pitched as "science".
> even had the engines 'gifted' to them so they didn't have to develop them
That is actually a large part of the problem from what I can figure out. This program is trying to take hand me downs designed and built by engineers that are dead or long retired now and having to reverse engineer them to fit them in. Many times this is much harder than just going pure greenfield and do something new. They HAVE to be ultra conservative on tests, because many of the parts just aren't replaceable currently. The consequence of that is later when failures happen with the old space shuttle components (again) with live humans aboard (again).
Figured out a while back as a software engineer that legacy code will eventually hit a point where F it, it's time to create something new as it takes too much time to maintain that mass of spaghetti.. Also found similar on my house, where after starting "renovations" it turned into a rebuild, and would have been cheaper, easier and FASTER to bulldoze and build new.
Figured out a while back as a software engineer that legacy code will eventually hit a point where F it, it's time to create something new as it takes too much time to maintain that mass of spaghetti..
Doesn't really work that way with rocket engines. These burn H2 and LOX - the recipe for the best in-vacuum performance. H2 is bastard hard stuff to work with, and a fresh design is going to be at best only incrementally better than the existing design. Redesigning those things is likely not going to produce any worthwhile benefits.
SpaceX are avoiding H2 by using methane - basically a compromise between very difficult engineering and performance. It performs better than kerosene, but isn't as hard to engineer for as H2. That's fine, because the only performance targets they need to meet are their own. But AFAIK they won't be able to achieve as high interplanetary velocities as the SLS.
It doesn't really work that way with many other things too. If you want a Mach 2 airliner, it's always going to end up looking a bit like, and share many of the same basic technologies, as Concorde. No one's really improved on the car.
Assuming that SpaceX can get the in-orbit refueling to work then the SpaceX rockets should manage higher velocities than the SLS . Starting from Earth orbit with full fuel tanks should easily beat the maximum performance of the SLS.
If (fat chance!) NASA and the US politicians were honest, they would admit that the SLS is totally outclassed by SpaceX and terminate the program immediately.
Icon for what should happen to the SLS program =========>
How is SpaceX going to get the extra fuel into orbit so that it can do the in-orbit refueling?
It seems to me that most of the fuel is used up getting to orbit. The more payload they try to lift, the more fuel it will take. As you can tell, I'm not a rocket scientist by any measure.
"How is SpaceX going to get the extra fuel into orbit so that it can do the in-orbit refueling?"
For that type of mission profile, I think you launch one or more rockets that just carry fuel to orbit. Then you launch your interplanetary vehicle, rendezvous with the tanker vehicle(s) and top off the tanks.
Alternatively, if you develop the ability to manufacture fuel on the moon, you use the moon as your gas station on the way to another planet.
I've never even played KSP, so hopefully someone more informed than iI can confirm.
Which is why hydrolox is used in upper stages. There are trade offs though. Hydrolox requires much larger tanks increasing dry mass. Boil off is much harder to manage. Hydrogen is far more likely to leak. If the stage is reusable hydrogen embrittlement becomes a significant concern. These other factors mean hydrolox doesn't necessarily have the best performance despite having the highest Isp(Well for chemical rockets. Electric propulsion is far better). To be sure we have to work the trades.
The problem with your argument is we are talking about a first stage. First stages need high thrust much more than higher fuel economy. Hydrogen's low energy density is a huge penalty here which is why the SRBs are required. Consider that without the SRBs SLS would have less thrust than Falcon 9 and it makes sense why we would want to use hydrocarbon fueled first stages.
As to, "But AFAIK they won't be able to achieve as high interplanetary velocities as the SLS." that's only true if you ignore refueling. SLS doesn't have this capability so assuming Starship works as advertised Starship will allow much higher interplanetary velocities.
With all that said what really matters is cost. SLS launch cost estimates are now exceeding $2 billion. Falcon Heavy(FH) fully expended has a list price of $150 million. FH can send roughly two thirds as much payload through TLI so a Moon program based on FH would be able to send about nine times as much mass per tax dollar compared to SLS. Starship should be even better.
SLS is good for distributing pork though.
Sorry for the delayed response. There is too much politics on the left side of the pond.
Agreed, but recall Red Dragon. TMI(Trans Mars Injection) is 4.3 km/s while TLI(Trans Lunar Injection) is only 3.2 km/s. This means we know Falcon Heavy can send Dragon through TLI. Thicken Dragon's heat shield, upgrade the comms system, and Dragon could replace Orion for crew transfer. We don't have any other massive payloads because Congress never funded any so you've raised a moot point.
>>Doesn't really work that way with rocket engines.
The engines regardless of what they're using for fuel need engineers experienced with the design and building of same. NASA hasn't kept their core competency for engine designs, and let that go decades ago. Hence trying to use old engines thinking it was the safe route, but maybe without the full expertise needed to actually re-use the old engines in a new rocket design
Doesn't really work that way with rocket engines. These burn H2 and LOX - the recipe for the best in-vacuum performance. H2 is bastard hard stuff to work with, and a fresh design is going to be at best only incrementally better than the existing design. Redesigning those things is likely not going to produce any worthwhile benefits.
Don't forget that there's only a finite number of the Shuttle's RS-25 engines in existence. We're not going to run out because SLS won't launch more than twice - but if there was some risk of it being used regularly then we'd have to start manufacturing new ones, which we haven't done for decades. If that happened, they're not going to do it how they did it in the 1980s. They're going to use modern manufacturing techniques - many-axis CNC, DMS. Major components are going to be redesigned to be manufactured using modern methods. If you're doing that, then you'll end up optimising and improving the design, at which point you're not far off doing a clean-sheet design using the existing engines as a reference.
No one's really improved on the car.
Err... Modern car design is a whole different beast compared with the 1970s - yet many rocket engines in use are only a few iterations from Apollo. Cars have improved annually - safety, efficiency, comfort, reliability. SpaceX's Raptor engine may use less-efficient Methane, but are massively innovative, being the first Full-Flow Staged Engine to make it off the test stand and fly - they've traded off fuel for a more complex design which wins efficiency gains over the (Fuel-Rich) Partial Staging of the Shuttle's RS-25.
SpaceX are avoiding H2 by using methane - basically a compromise between very difficult engineering and performance. It performs better than kerosene, but isn't as hard to engineer for as H2. That's fine, because the only performance targets they need to meet are their own. But AFAIK they won't be able to achieve as high interplanetary velocities as the SLS.
That's absolutely true.
But at this stage, nobody cares. Multi-billion-dollar single-launch moon missions worked for Apollo when no other infrastructure existed, but they aren't sustainable for running a moon base and are wasteful in a solar system where you have space stations and intermediate ports. SLS is never going to send people to Mars because the capsule is far too tiny for multi-month voyages. Inevitably you'd assemble the Interplanetary ship in orbit, launch crew in conventional capsules and transfer (as per The Martian) - or if you're SpaceX, launch the lot on StarShip and refuel in LEO.
There's possibly a niche use for lobbing up science probes going to outer planets, but at this stage the costs are working out far in favour of using a BFR to truck mass LEO. If you need a super-efficient H2 stage for going to Uranus, then F9H/New Glenn/Starship can take you to (or past) LEO and you can use your own H2 upper stage to boost you out - using it for the first stage is of very marginal benefit given the difficulties in handling and engineering. Maybe it's a bit more efficient and elegant - but if it costs you a billion dollars instead of $100m, then you'd be a fool (or a pork-barrelling politician) to pick the SLS option.
>SpaceX are avoiding H2 by using methane - basically a compromise between very difficult engineering and performance. It performs better than kerosene, but isn't as hard to engineer for as H2.
It can also be made on Mars, waiting for Mars to have an oil industry makes a kink in their return schedule
>Figured out a while back as a software engineer that legacy code will eventually hit a point where F it, it's time to create something new
And I figured out that young guns always think they can do better, which is why we end up with so many wheels.
Good code does not inevitably corrode. But it does require intelligent maintenance. It's the hacking around by incompetents which does the terminal damage.
And it's the same with hardware, and absolutely with houses. Get a good builder.
Starting again is always more fun of course, as Elon knows very well...
>> Figured out a while back as a software engineer that legacy code will eventually hit a point where F it, it's time to create something new
When you start from scratch, you always - always - encounter all the undocumented exceptions to the rule and oddities that made the original code more complex than it appeared to require. I'm not saying a redesign isn't a good idea, but it's going to take longer than you've estimated, guaranteed.
(first in an infinitely long series of "things I've learned the hard way after 30 years of writing software". Sadly not all of my team have hit this point, hence anon)
>> When you start from scratch, you always - always - encounter all the undocumented exceptions to the rule and oddities that made the original code more complex than it appeared to require. I'm not saying a redesign isn't a good idea, but it's going to take longer than you've estimated, guaranteed.
Yep. Also been around the block for 30+ years. I HATE starting over from scratch, but at a certain point, it's time. And strangely enough, when it's time, if you've been around long enough you seem to know. Don't like it, but you know. This is versus exuberant pups who want to rebuild everything just because X language is so much cooler. :) Nothing worse than dealing with barely doc'd or undoc'd spaghetti code that over the years just kept getting tacked onto and ultimately used inconsistently with how it was originally architected. Then there are the stupid things in the old program that you find out WHY they were there on your first run. :)
Just yesterday, I was talking to a recruiter about a project that was doing a rebuild from scratch. My considered response? "There be dragons--so get your lance & full armor on, because it's gonna get hot."
Yes, there are times that full redo is the right decision. I've seen two in 25 years. Neither were actually attempted.
SLS - Senate Launch System. It's a pork program, like most of everything in government.
Government cost plus - $20B development (with gifted engines), plus operations, plus vehicles and launches ~ $30B?
Private Enterprise - SpaceX Starship $? total unknown. However, Falcon Heavy can launch the same amount of payload of SLS with three launches and still be 1/3 the operational cost of SLS.
Any question about why government should do as little as possible is well illustrated here. Unless of course you are one of those contractors...
exactly - a 'Total Inability To Sustain Usual Parameters' event resulting in a ginormous "ooh, aahh" ball of "system integrity loss" would have cost a LOT more and set them back a LOT further. 400 additional seconds of fuel would make ONE HUMONGOUS FIREBALL, after all.
A look at Apollo 2 through 6 would confirm this approach (wikipedia articles on them are interesting and appear to be accurate). After Apollo 1, they needed to be more careful to identify potential problem before they become fireballs. Similarly with the shuttle losses. Space is (currently) a dangerous business, just like flying was 100 years ago.
This.
100% is engine power at optimal fuel ratio. For liftoff you want a little bit of extra oomph to get things moving, so you go a bit "extra" and get more out of the engine for a bit. The engines throttle down as the craft gets moving and approaches "Max Q" then throttle back up to 100% for most efficient burn until MECO.
They had equipment failure and their test failed under perfect conditions, and the problem is the test parameters were too restrictive and everything will be all right when we put people on top of it and light the candle?
Well, failure to make orbit was a success previously. So maybe.
If you test engine gimballing over its full range while in flight you will also test the vehicle's performance in pointy-end-down configuration quickly followed by an ambitious lithobraking manoeuvre. With enough duct tape the booster can be strapped to the test stand and remain flamy-end-down whatever you do with the thrust vector controls.
On the space shuttle the hydraulics had to work days after the hydrogen tank had been emptied and dropped into the ocean so they were powered by hydrazine. Hydrazine is sufficiently unpleasant to work with that hot high pressure hydrogen is actually easier - especially as you have 4x RS-25 engines each producing more than you would ever need to power the hydraulics.
Someone sensible proposed testing this new power system by gimballing the engines over their full range about one minute into the test (when the rocket would start to tip over onto its side when in flight). I assume the relevant politician leaped out of his seat jumped up and down with excitement shouting "Yes! Yes!!", calmed down and ask what was the largest amount of money taxpayers could contribute for this without looking completely silly.
On the plus side the test covered a range of motion that is extremely unlikely on a real flight. The power for the hydraulics is provided by multiple redundant systems and failure of any one would not cause loss of mission, let alone loss of crew. On the minus side this was not a SpaceX experiment with manufacturing test article 9 performed with test article 10 ready, waiting and using much needed space in the high bay. This was a verification of years of simulation and modelling that was supposed to prove the design before any construction even started. A sensor reading out of range shows there is an important detail missing from the model that makes the simulation invalid.
There are two obvious ways to proceed: identify the missing feature of the model, re-do all the simulations, correct the design and manufacture a new booster. Or you could just widen the acceptable ranges on the sensor data.
Normally I would expect congress to wet themselves and vote "YES!" to any opportunity to increase the costs and extend the project for another two years. This time there is a huge deficit, a trashed economy, a pandemic and Republican senators will riot over any spending where the Democrats might possibly be able to take some credit. On top of that SLS's days are numbered by the progress of Starship. Extra delay just reduces progress before cancellation rather than actually increasing the number of welfare cheques to Boeing.
Normally I would expect congress to wet themselves and vote "YES!" to any opportunity to increase the costs and extend the project for another two years. This time there is a huge deficit, a trashed economy, a pandemic and Republican senators will riot over any spending where the Democrats might possibly be able to take some credit. On top of that SLS's days are numbered by the progress of Starship. Extra delay just reduces progress before cancellation rather than actually increasing the number of welfare cheques to Boeing.
Ah, the politics around the Senate Launch System. Arguably the Democrats should take some credit, ie Obama's 2010 NASA funding bill, and then various stipulations like SLS must use recycled shuttle components. And then Trump telling NASA to get back to space, but AFAIK not allocating all the funding NASA said it needed. Which then led to more politicing, and interesting suggestions like using RD-180 engines instead of RS-25. But the RD-180's are Ukrainian/Russian, so politics.
So much of the anticipated launch cost comes from having to use/re-use the old Shuttle engines, and there's a finite number of those. Arguably it would/could have been better if NASA had just been given budget and mission parameters to develop from a clean sheet and find the 'best' engine. A bit like with ULA's replacement for the Atlas rockets, and choosing Bezos's BE-4, or developing a domestic version of the RD-180.
Either way, the pork will continue to flow, just to different maws. Starship is running on hype and welfare, ULA's Vulcan is slipping. Politically, it probably makes sense to keep competition, or keep pork barrels rolling for the US to maintain capability & skills across it's aerospace industries rather than relying on picking a winner. Commercial launches can do that, but many launches are funded with tax dollars.
SLS was a bi-partisan effort. Obama cancelled funding for Constellation and wanted to go with fixed cost commercial contracts to supply and staff ISS. The whole of congress threw a tantrum at the loss of Constellation pork and demanded they have their SLS project to handle as they saw fit in return for commercial resupply and commercial crew. By all means blame Obama for CRS and CC but the whole of congress, Democrat and Republican should take credit for SLS and requiring NASA to use existing Space Shuttle parts and manufacturers.
I do not know who said "boots on the Moon by 2024" to Trump, but the result was as anticipated: Trump approved congress supplying mountains of pork to all the usual suspects (but not enough for the project to stand any chance of completing on time).
Starship is running on hype and welfare
I missed that. What percentage of Starship funding comes from the US government? (If you mention government purchases of Falcon 9 launches I will take that as negative funding: {SpaceX launch price} - {cheapest competitor price})
I do not know who said "boots on the Moon by 2024" to Trump, but the result was as anticipated: Trump approved congress supplying mountains of pork to all the usual suspects (but not enough for the project to stand any chance of completing on time).
Yup, politics. Make it so, and make it so it happens during my second term. Oops. But I think a renewed focus on space, especially manned spaceflight was a bit of an achievment for Trump. Which was also probably a bit political given the space endeavors from China, India etc. The US put man on the moon, then gave up.
I missed that. What percentage of Starship funding comes from the US government? (If you mention government purchases of Falcon 9 launches I will take that as negative funding: {SpaceX launch price} - {cheapest competitor price})
Challenge with SpaceX, and some of it's competitors is it's private. But just cribbing from wiki-
US$12 billion EELV payloads
US$396 million Cargo Dragon development
US$1.6 billion Commercial Resupply Services
US$75 million Launch Escape development
US$440 million Dragon 2 development
US$2.6 billion Complete & certify Dragon 2
US$290 million Launch 3 GPS satellites
US$316 million 1 NSSL launch
And then $900m from the FCC to subsidise Starlink. There might be some overlap in the above, but still an awful lot of pork flowing from NASA and the US military. Strangest part for me is this statement-
These Space Act Agreements have been shown to have saved NASA millions of dollars in development costs, making rocket development ~4–10 times cheaper than if produced by NASA alone
Now, if I were President, I'd be putting a rocket under NASA to find out how & why for-profit venture(s) can do it so much cheaper than the Federal entity that's supposed to do this stuff.
But I think a renewed focus on space, especially manned spaceflight was a bit of an achievment for Trump.
The successful US manned space flight was Crew Dragon which was half of Obama's Commercial Crew program (It is remotely possible that the other half: Boeing Starliner will be successful too). Trump did do one good thing for US Space flight: he delegated the whole thing to Mike Pence. There are plenty of horrible things to say about Pence (some of which Trump said before he found out no-one else would run with him) but Pence does understand politics and government. My personal bet is Pence came up with bipartisan support for Artemis pork then said "Boots on the Moon by 2024" to Trump. Trump (or Pence?) came up with Jim Bridenstine for the new administrator for NASA. Bridenstine has proved outstandingly competent compared to other Trump appointees. He successfully defended CC budget against attempts to divert it to SLS. He reduced the number of NASA employees who were working for Boeing. CC succeeded because Trump left all the work to others. Artemis is currently 90% pork project, 10% space project. I think Hilary would not have been able to stop it any more than Obama and SLS but she might have got a better deal for US taxpayers.
Thank you for making my point about Starship not being government welfare. Lets take that $1.6B for for CRS1. That bought 12x Cargo Dragons with a payload capacity of 6000kg each to the ISS. As a part of CRS1 NASA also bought 8x Cygnus flights for $1.9B. As Cygnus can only take 2000kg to the ISS it would need 36 flights costing $8.55B. Even if you throw in the other costs you mention related to Cargo and Crew dragons the CRS1 deal with SpaceX still saved NASA $3.3B. Likewise that $12B for EELV payloads would have cost far more from any other supplier. To really rub salt in your wounds, I just included some CRS2 and CC costs without including CRS2 benefits, future CC benefits and the benefit of having cargo taken from ISS to Earth.
Likewise that $12B for EELV payloads would have cost far more from any other supplier. To really rub salt in your wounds, I just included some CRS2 and CC costs without including CRS2 benefits, future CC benefits and the benefit of having cargo taken from ISS to Earth.
No salt, simply pointing out the amount of pork thrown SpaceX's way.. Which includes NASA paying R&D on various elements of SpaceX's systems. Which seems normal for NASA, ie Boeing, Rocketdyne etc etc.. But there's undeniably a lot of corporate welfare thrown SpaceX's way, which can (and arguably does) distort competition. Especially if you lowball bids to win those, and then cross-subsidise. But like much of the space programme, a classic way to socialise costs & privatise profits.
None of which really answers the question as to why NASA can't design a rocket engine at close to current market rates.
"A sensor reading out of range shows there is an important detail missing from the model that makes the simulation invalid"
Or, if only one of four attached to that test article, a dodgy sensor? Which is more likely; three sensors would, to the millisecond, fail to record an error that gets spotted by one lone sensor, or one lone sensor fails and indicates a problem that does not, in reality, exist?
That was bad writing on my part as a separate problem was a bad redundant sensor. The actual cause of the abort was low hydraulic pressure. That pressure was correctly measured by sensors and the software responded as instructed by shutting down when then pressure dropped below 50psig. There is discussion about whether 50 is the right number. Presumably the simulations showed correct operation at 50 and that the pressure would not drop lower than that hence something about the model is not correct.
(I have since seen an unconfirmed rumour that the low pressure was cause by a valve opening 0.2 seconds late.)
This was a verification of years of simulation and modelling that was supposed to prove the design before any construction even started. A sensor reading out of range shows there is an important detail missing from the model that makes the simulation invalid.
This is what bothers me. When I'm testing software I never worry about the things I know to test. I build my test cases and expect everything to pass. I don't make excuses why something 'almost worked'. If it's test parameters then you fix them just like a defect. What worries me is there are ALWAYS things that could fail that you don't know about. You either find them and fix them during testing, or it bites you in the ass in the real world.
Boeing isn't going to build a dozen test vehicles and 'fail early' like SpaceX does. With their recent track record, saying "no worries, it's just a bad test parameter" isn't good enough. It was just a 'bad test parameter' on a clock that caused their launch problem on their test capsule.
Scott Manley reviews it here-
https://www.youtube.com/watch?v=Yi-fBKK7nME
In which I learned that 747s came with a hardpoint. Wonder if there was ever any plans to use them as 'stealth' bombers, rather than an ability to haul a spare engine. Been looking to see if I can find any images of that, but a 5 engine 747 must be a strange sight.
Back in the 1970s, Boeing - sniffing the air for delicious pork - came up with a plan to use the 747 to launch cruise missiles:
https://foxtrotalpha.jalopnik.com/why-boeings-design-for-a-747-full-of-cruise-missiles-ma-1605150371
And here's a photo of a 747 ferrying a spare turbine - as you say, it looks strange:
https://www.flightradar24.com/blog/how-qantas-ferried-an-engine-on-the-wing-of-a-747/
Cheers for the pic! And I guess a 6 engined 747 would look a little more balanced. I also remember when I lived in Cambridge, an aircraft flew into Marshalls Aerospace with a big launch tube slung underneath it. Can't remember what aircraft it was, but think it was an experiment to do what Virgin just did, ie a potential satellite launch system.
Does that mean A) the thing was liable to blow up or B) extreme limits were set too low?
If (A) then they are in trouble as it's liable to blow up ...
If (B) then why? Either they were extreme limits or they were limits that someone dreamt up for no reason and that means the design methodology is fundamentally wrong and they are in trouble ...
Conclusion 1 ... they are in trouble.
Conclusion 2 ... any astronaut riding this thing based on 'tweaking' the limits rather than fixing the fundamental issues needs their heads tested.
...and that horse is SpaceX.
When you look at what SpaceX has achieved in what is actually a very short period, you realise that Boeing is so far behind.
Everytime I see a vid of SpaceX standard launches for satellites, and see the boosters come back down to land with almost metronomic predictability, that must be very depressing for the legacy space manufacturer.
Quite frankly, I found the flight of Grain Silo 8 , sorry SN8, nothing short of remarkable for what looked to have the aero of a brick in so many ways.
But then, when you see how backwards Boeing seem to be going in standard aviation, should we be surprised?
Boeing was doomed the second it was taken over by MD management and put the managers in charge and in a different city, so they couldn't be bothered by those pesky engineers.
The Boeing of the past, that put out the 747 as a side project just in case the SST didn't workout, that designed the iconic 737 and played a huge role in the development of military and passenger aviation was led by engineers first and foremost. People that had a feeling for their product and understood what it was they let roll out of the hanger doors at the end of the production line.
If the intent was to stress the system, an APU fault and the resultant system adjustment to the fault would be valuable information. As a test engineer, stressing a system means one has verified the "tighty-whity" parameters and it's time for the relaxed bounds testing to begin. SO, either the person quoted doesn't understand what a stress test is (Typical manager), the test team doesn't understand that to stress a system means relaxing bounds (More than a bit scarry), or someone missed a pre-test step to relax said parameters... I'm going with the goof.
Depends on what the hydraulic pressure controls. If the fuel/oxidizer control valves run off that same hydraulic circuit for instance I could imagine you'd want to shut things down before pressure drops to a level where you might no longer be able to control the valves.
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