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AdminsFuckedMeAgain t1_jamfwaa wrote

Doesn’t this flight make Falcon 9 the most reliable rocket in history now?


AWildDragon t1_jamlalr wrote

It’s got the longest current success streak of any currently operational rocket.

Older Soyuz may have beater it but that’s the only thing that could. Recent Soyuz qc is a mess and they don’t have the flight rate anymore.


OSUfan88 t1_jamu519 wrote

It's slightly complicated, and depends on how you measure.

Many consider the Falcon 9 Block 5 to currently have the lowest chance of failure of any rocket. That being said, An earlier version had a failure on ascent (and 1 more on the pad testing).

Atlas V has never had a total mission failure, so you can't get better than "100% mission success". That being said, it has had some partial failures. People can debate the semantics of whether it is or not, and depending on which metrics they find most important, be correct. It can be said that it's an EXTREMELY safe rocket in it's current form.


Here is an awesome post which makes the case that Falcon 9 landings are now more reliable than any rocket ever. The basis of this is that Falcon 9 has successfully landed 101 times consecutively. The highest any non-SpaceX rocket has had success launching is the Delta II, with 100 consecutive successful launches.


Bewaretheicespiders t1_jamwrro wrote

Atlas V would have a pretty tight confidence interval on that 100% reliability yeah.

With that number of flight there is only a 0.6% probability that Atlas' V "actual" reliability (partial or total success, were it to fly an infinite number of time) is less than 95%

So if I remember my Stats correctly, and its been over 20 years so bear with me, we can say with 99% confidence than Atlas V's is at least 95% reliable?


Jakebsorensen t1_janauba wrote

Doesn’t the Saturn family of rockets have a 100% success rate?


Doggydog123579 t1_japetb6 wrote

Yes, however sample size matters. The odds of having a run of 5 launches without failures is better then 10. So if both have a perfect record, but one has only flown half as much, the one with the higher number of flights is statistically more reliable


Whoelselikeants t1_jant4qu wrote

Delta IV heavy is 100% reliable


Chairboy t1_japzcsu wrote

Tell that to Sparkie and Ralphie from the inaugural launch.


Shrike99 t1_jauoplw wrote

Over a small number of launches though. It's commonality with Delta IV Medium gives it some more credit, but generally speaking I'd rather fly on a rocket with 1 failure in 100 than 0 failures in 14, even though 99%<100%.

I used to make the point that Epsilon is also 100% reliable, but that since it only has 5 launches under it's belt that doesn't amount to much in practice.

I was quite vindicated when it recently failed on it's 6th launch, though also a little saddened that I'd no longer be able to use it as an example.


Whoelselikeants t1_jaxry2g wrote

Well I expect Delta heavy to fly more also since the interest in mars science is ramping up along with Falcon heavy. Still, not having a failure in 14 launches of one of under a dozen special case rockets is pretty good.