Hacker News Reader

Comment by sandworm101 | Hacker News Reader

My point would be that while SpaceX does save lots of money, it doesn't do so by producing cheap or less reliable rockets. It would never accept a failure rate any different than anyone else because, in aerospace, that isn't really a thing. SpaceX can certainly blast forwards with different business practices and different tolerance for developmental risks, but the final product will not be fundamentally different than anyone else: near-perfect machines resulting in near-perfect performance. There will never be a "cheap" version of a commercial rocket with an accepted less-than-perfect failure rate. Spaceflight is an all-or-nothing game.

View on HN

> My point would be that while SpaceX does save lots of money, it doesn't do so by producing cheap or less reliable rockets.

It does though. During the development process. SpaceX will do five launches with lower reliability vehicles before the big launch providers will even do a single launch, and those five will have be cheaper in total. Of course, they aren't putting essential cargo (or god forbid people) on these higher risk test flights. By the time they're doing that they have developed certainty in the design.

> Of course, they aren't putting essential cargo (or god forbid people) on these higher risk test flights.

A number of Tesla-related deaths can be attributed to Autopilot malfunction. Real people - really dead.

Different company. This is about SpaceX.

And statistically many more people would have died without AP. But you're correct in that Tesla is using the same playbook on FSD as SpaceX, launch HW (and SW) early and iterate often, and I'd bet they'll save way more lives trying to get to autonomy like SpaceX rather than like NASA (the Waymo approach).

> But you're correct in that Tesla is using the same playbook on FSD as SpaceX

Except Tesla, unlike SpaceX, is willing to put passengers in its test vehicles. The SpaceX approach would be to let a bunch of FSD Teslas crash into things and each other before giving them payloads.

Tesla is willing to put UNWILLING people in its tests (other road users, pedestrians).

I “unwillingly” have to share the road with people who murder 40,000 people a year with their vehicles. Thankfully we are developing the technology to get these reckless maniacs out of the driver’s seat.

Putting someone in an experimental rocket is quite different from being essentially a safety driver required to pay attention and take over at any time. If you have an accident on FSD is is probably (though not always) your fault for not paying attention.

> And statistically many more people would have died without AP.

Citation needed. Not Tesla's "stats" that if the people compiling them completed anything more than high school statistics are intensely misleading.

Comparing a subset of miles driven on the simplest and easiest roads (because the systems can't be used and are turned off) and comparing to accident stats across ALL roads is disingenuous to the extreme, and Tesla continues to tout it.

Short of pulling over, humans don't have the opportunity to say "let's disengage, because it's a bit challenging", and then not have to worry about "counting" any accidents from there forward.

Agreed. It’s like if I unit tested 0.01 percent of my code but ran the unit test 10 million times, with no failures, and claimed it was therefore “statistically” better than code that had been 100% manually tested.

No, they segment between _vehicles_ using AP vs not (still Tesla), not segmenting by miles. https://www.tesla.com/VehicleSafetyReport

I wasn't talking about Tesla though and I don't know why you assumed I'm pro-fake-Autopilot????

A number of Tesla related non-deaths can be attributed to Autopilot safety features working as promised. Tesla will argue that the number is higher, based on number of crashes per mile statistics. I'm not sure if that's true, but assuming for everyone who died due to an Autopilot failure, someone else survived a human error crash that didn't happen, would that be a good thing? What about if it was, for example, 10 people saved for every 1 killed?

I'm reminded of runaway trolleys.

I think it is a subtle difference.

SpaceX does not have a difference in intended reliability, or a difference in design reliability. (At least for the rocket as a whole. One could argue that 33 engines allows lower engine reliability through redundancy)

What they DO have is a significant difference in prototype reliability for live launch. This is clear when you look at their launch history.

Or one could say that SpaceX has basically the same tolerance for failure as the traditional rocket companies had back in the 50s and 60s when they too were first learning to build rockets. That pre-launch "tolerance" is basically zero, with every post-launch failure being investigated as a mistake to be corrected rather than an acceptable cost of doing business.

>That pre-launch "tolerance" is basically zero

I don't think that is accurate. There is a difference between 9%, 99%, and 99.999% confidence of success going into a launch.

You can almost always delay builds and launces to run more simulations, tests, and studies and increase confidence.

A simple example is SpaceX could have chosen to wait until they had a booster test with 100% engine ignition before moving on a full launch. Instead they choose move forward anyways without more stationary booster testing.

> There will never be a "cheap" version of a commercial rocket with an accepted less-than-perfect failure rate. Spaceflight is an all-or-nothing game.

Why? If you're launching people I see why you want near-perfect, but if you're launching something with a low replacement cost (ex: getting fuel to orbit to support other projects) it seems to me that as volumes get large enough eventually "use lower quality and accept a slightly higher probability of failure" starts to be cost effective.

Because there is no way of building a cheaper rocket with a less reliability. Take aircraft. Does anyone deliberately build cargo aircraft with less reliability than passenger aircraft? Does anyone build a smaller airliner with less reliability than the big airliners because fewer lives are at risk in the smaller aircraft? No. All aircraft are designed and built to amazingly high standards because, in such as complex high-energy environment, there is no money to be saved by building less-than-perfect machines.

I'm with you on spaceflight but people definitely have built small cargo carrying UAVs to a lower standard than passenger aircraft. Such a thing is conceivable anyway.

Ya but smaller UAVs aren't operating in the same energy environment. They are small enough that them randomly dropping on people's houses doesn't matter much. Aerospace is about things large/fast/high enough that all failures put lives at risk.

Okay, so you're not saying it has to be expensive, but almost the opposite? Perfect and slapdash have similar production cost, so properly designed rockets will all be just about perfect?

Most cargo planes are expected to run out of civilian airports where a failure could result in debris launching themselves into populated vehicles or buildings. In contrast a crop duster launching off a dirt runway and expected to go no more faster than highway speeds actually can be built fairly loose, and often are. For example, this duster here [1] won a award in the 70s for innovations like a "pressurized cockpit" and "air conditioning".

[1]https://en.m.wikipedia.org/wiki/Grumman_Ag_Cat

Listen, we don’t need to speculate. Read the History of Falcon9 development.

Your comments in this thread all go against the development approach of that rocket— Falcon9 is a stable platform now as it is used in production. In the development phase there were tons of explosions. This all happened in the past.

This is simply not true. Rockets require significant additional testing to become human flight rated, even if they are already cargo rated.

Is unarguably cheaper to forgo the additional testing and cost required for human flight.

No. All aircraft are designed and built to amazingly high standards because, in such as complex high-energy environment, there is no money to be saved by building less-than-perfect machines.

But this is totally false. There are entirely different standards applied if you want to design an aircraft for commercial airline passenger transport vs for general aviation. There are entirely different requirements for instrumentation reliability if you're building a day-VFR aircraft vs one that is allowed to fly in instrument conditions. And there are entirely different requirements for aircraft that you sell to the public vs ones that you build yourself.

The aviation side is full of examples of exactly the sliding scale you're saying doesn't exist.

> there is no way of building a cheaper rocket with a less reliability

Of course there is. The famous example is radiation hardening. SpaceX opted for redundancy instead. Not only cheaper, but more modern, too.

> in such as complex high-energy environment, there is no money to be saved by building less-than-perfect machines

SpaceX has launched zero humans. (EDIT: Totally wrong!) It aims to, so target reliability is high. (I would argue their track record in production is a product of their willingness to push the envelope in tests.) But there is a large market for cheap, if unreliable, launches. Because there is an emerging market of cheap satellite makers.

SpaceX has launched 9 crew missions with around 30 or so humans.

It is the only US entity with the capability to do so.

> SpaceX has launched 9 crew missions with around 30 or so humans

Sorry, had a brain fart, no idea how I typed that out.

Low quality rocket full of fuel? I don't think anyone wants it on their launch pad.

The testing rocket is less reliable (and unmanned). The tests happen earlier in development

> My point would be that while SpaceX does save lots of money, it doesn't do so by producing cheap or less reliable rockets

Indeed, if we assume that the each launch is an IID binomial coin flip (which isn’t really the right way to evaluate right-censored data), and observe (by reading Wikipedia) that SpaceX has had at least 450 successful Falcon 9 launches since the last in-flight failure, then they have at least five nines of reliability:

0.999995^450 ~= 449/450.

Which appears to be an industry-leading stat.

For context (excluding the Columbia re-entry failure), the space shuttle only had 4 nines:

0.99994^125 ~= 124/125

I'm going to challenge those numbers: Using a posterior probability density function for a binomial distribution, the lower bound in Falcon 9 reliability is .9934 with 95% confidence (assuming 450/450 successful trials). The reliability of F9 could be much lower than five 9s and still reasonably give you 450/450 successful trials. There's only a 0.44% chance that F9 reliability is at least five 9's given the data.

> it doesn't do so by producing cheap or less reliable rockets

I saw in another comment that each SLS launch costs $2B. Do you think SpaceX spent $2B on this launch? I find it hard to believe.

>There will never be a "cheap" version of a commercial rocket with an accepted less-than-perfect failure rate. Spaceflight is an all-or-nothing game.

substitute rocket and spaceflight with airplane and flight and see how that sounds

Sounds exactly the same. There are no cheap aircraft. Everything that flies is subject to innumerable laws and regulations to ensure that it is built to exceedingly high standards. There is no such thing as a discount aircraft with lesser reliability. Some are cheaper than others but none are deliberately less-reliable, not in any fundamental way. Even ultralights have to abide many regulations.

I can buy an ultralight with cash. I can't come close to a commercial aircraft with cash.

Yes ultralights have some regulations, but even general aviation has less regulations resulting in cheaper aircraft, to say nothing of ultralights.

Reply on news.ycombinator.com