Let's open with:
TL;DR, (because sferrin is not wrong
)
My experience/background is from working with aircraft/munitions/electronics systems that in some cases have wildly exceeded their 'design/planned' life while in others have not failed for various reasons before even scratching the surface of that time so when I comment on a similar bit more of a 'clue' than you think I do. A truism for a system is that the design/planned lifetime for something that as of yet has not achieved anywhere near the stated number of flights is going to be based on assumed and extrapolated conclusions and by its nature therefore inaccurate. As time and testing improve this data so will the estimates be changed, possibly radically, in one way or another. This, in my opinion is what we're seeing from SpaceX. It does not invalidate the initial planning or design but it does affect them and future efforts.
Musk has clearly said Falcon 9 is designed for ten reuses before it needs major refurbishment, then it goes for another ten and so on.
Musk has clearly said Falcon 9 is designed for ten reuses before it needs major refurbishment, then it goes for another ten and so on.
Agreed. Main item of refurbishment are engines.
Here are citations of 100 flight re-use:
https://insights.globalspec.com/art...lcon-9-rocket-to-endure-a-100-launch-lifespan
https://www.popularmechanics.com/space/rockets/a20152543/spacex-test-fire-new-falcon-9-block-5/
https://en.wikipedia.org/wiki/Falcon_9_Block_5
My point has been that they still need to show that and they have yet to hit the 10 flights goal itself. My other point was that they MAY be seeing issues that may actually preclude that end goal. I wasn't the one who went off on a tangent that Musk must be "lying" to investors if that goal in fact cannot be achieved or they are finding it more difficult than originally thought to do so.
That is in fact how you determine the actual rather than designed/planned limits to an airframe.
Your posts implied a level of technical command and financial insider experience that I did not associate with "an ex-military aircraft/munitions/and-electronics maintenance worker". You can dismiss my posts as uninformed guesses and I can do likewise for you.
That's maybe because I may have a bit better 'grasp' than you were assuming in the first place
I could be making more informed "guesses" than you think because i have experience with similar complexity systems and economics. I could of course be talking out my backside and you're quite free to assume so and act accordingly but let me point out that it IS the operational, maintenance and practical economic side that we are currently discussing.
You asked earlier why I brought up the "100 flights" when we were "talking" about 10 fights but that's part of the point. When you get right down to it picking "100 flights" as a goal is a very telling point about the assumed and hoped for maintenance and serviceability factors of the Falcon. As one engineer I associate with has remarked on the current system I'm helping support likes to say, "We're 50 years into a planned 10 year deployment and some of our equipment amazingly still works" because planned and actual service life are not the same thing.
The goal is to fly the Falcon up to 100 times in 10 flight 'block' increments but that does not actually mean they assume that the booster will actually LAST for 100 flights. That's not how it works. Using rather standard "lifetime" assessment for an airframe a "life" of 100 flights means that as time goes on each successive "maintenance" block will have an increased chance of the booster and components NOT passing and therefore being retired. A design life of 100 flights literally means that by flight 99 the booster is likely to have around a 99% chance of failing due to fatigue and use. And that is based on the original assumptions and calculations being 100% accurate which is rarely the case.
A 100 flight "lifetime" is easily divided up into 10 each 10 'block' flights, which easily enough works out to about a 10% increase per 'block' of the booster being either too expensive, (costs for rebuilding/refurbishment also go up as lifetime decreases) or too "old" (accumulated damage over time) to be returned to flight. Note this isn't a hard rule but a rule-of-thumb but it pretty much generally holds true in aerospace terms. So once they complete the first 10 flight 'block' the booster would, according to their current assumptions be about 90% likely to need only engine and some other component replacement with a very low chance of any "major" airframe/component replacement or damage. But that can change as those flights accumulate and that can change the original assumptions and calculations reducing or even expanding the flight limits. In addition the example airframe itself could suffer some damage or malfunction that renders it unable or uneconomical to continue to use before it reaches any significant portion of its calculated lifetime. This may or may not also effect the original calculations.
And unlike rebuilding an engine, refurbishing an airframe doesn't 'reset' the time/number-of-flights counter so each flight has an increased risk of failure due to simple fatigue accumulation. So the time that a 50 flights on the clock it would be considered 'high-time' airframe and require even more extensive and in-depth checkout and refurbishment. Actually getting 100 flights out of a booster is highly unlikely and that is why the wording "planned" and "designed" is specifically used in that context. This in and of itself is not written in stone as the "planned/design' lifetime itself is based on some assumptions and extrapolations from data available for and from FAR fewer flights and by their nature could be incorrect.
We'll see of course, but in the very final analysis even JUST getting 10 flights out of a booster is a serious advance over current capability.
Randy
techcrunch.com
www.teslarati.com
