Was Falcon 9 1.1 overbuilt to support launch rates higher than needed?

[R7]

OP: "No, 80,000 people are waiting for high launch rate."

OCCUPY MARS!!!!!

http://silencedmajority.blogs.com/silenced_majority_portal/2012/08/occupy-mars.html :



P.S. SuperDraco

[sdsds]

No. F9 was designed to bring about (extremely) inexpensive access to space; F9v1.1 enables SpaceX to provide inexpensive access to GEO, which as it turns out was a necessary piece of extremely inexpensive access to space overall.

[RanulfC]

FWIW, I agree with almost everything in the above post, and its including quotes, well, except maybe the last sentence. Why Falcon 1 was cancelled, and what that means is one of the inconconclusive things I sometimes wonder about.

Why Falcon 1 was cancelled is off topic for this thread. I'll try to edit in where it could go, if I can find it. So far no luck...

Here probably:
http://forum.nasaspaceflight.com/index.php?topic=33686.0;all

Randy

[LegendCJS]

Irrelevant/ not applicable. Even if it was it is not a bad thing. To the extent that a rocket takes less time to get ready to launch it saves money. The question is only relevant if applied to the Falcon v1.1 factory/ tooling/ workforce / infrastructure, not the rocket.

[RedLineTrain]

In answer to the OP, we don't know if Falcon 9 v1.1 was overbuilt, because we don't know the spec to which it was built.

Is its design life 5 launches?  15 launches?  It seems possible to me that the current v1.1 vehicle is not really designed for reuse without further modifications.  In other words, SpaceX more or less might have tried to feel its way through the design.

However, even if reusability is taken off the table, sizing the factory to 400 engine peak annual output seems ambitious.

[faramund]

In answer to the OP, we don't know if Falcon 9 v1.1 was overbuilt, because we don't know the spec to which it was built.

Is its design life 5 launches?  15 launches?  It seems possible to me that the current v1.1 vehicle is not really designed for reuse without further modifications.  In other words, SpaceX more or less might have tried to feel its way through the design.

However, even if reusability is taken off the table, sizing the factory to 400 engine peak annual output seems ambitious.

But the 400 engine figure, as far as I know, was based on 10 Falcon 9's, and 10 Falcon Heavys. Which, as long as SpaceX can stick to their advertised prices, seems highly achievable. (yes.. I know that only makes 380 engines, but a 5% margin is fairly small)

[rpapo]

I just see a lot of posting all over the site where markets and waiting payloads are the overriding driver in in the specs of what SpaceX flies, to which I disagree.

And to which I disagree as well.  One must keep in mind that SpaceX's reason for existence is not to be a business launching satellites for the currently existing market.  That is simply a way to generate revenues to finance what they really want to do.

[Oli]

In answer to the OP, we don't know if Falcon 9 v1.1 was overbuilt, because we don't know the spec to which it was built.

Bingo, we don't know the specs.

Looking at...

http://www.spacelaunchreport.com/falcon9.html

...it doesn't seem to be overbuilt.

[Wigles]

In reply to the OP, I am not sure we have enough information to know if F9 is overengineered for an expendible launcher (which I assume you were implying due to the added weight to support reusability).

I believe that at a high level the concept would be proven that it supports growth into a reusable design. I am sure that the majority of the first stage could be reused at least one or two times already. The key will be when they start getting in-tact stages landing safely and can measure the deformation/stress on the airframe compared to their models.

They will find that some areas are probably overengineered and others are under, then they can add strength where needed.

So I hope that they havent overengineered the whole thing to support 100 reuses from the beginning because it is a lot of work and weight. But I dont doubt that they have a good idea already of what areas are likely to be the weak points and will be working to review and modify as they go.

[Dudely]

True, we don't know, but we can infer that robustness is an important feature from two important facts:

1) Quotes from engineers expressing their frustration at Elon's insistence on extreme reliability. I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.

2) They increased the weight of the baffle between the engines. It does not make sense to take a payload hit to protect the engines from each other unless you plan on routinely flying in situations where you expect an engine could fail (flying the same engines multiple times, for example). You would not want an engine failure to ruin an otherwise reusable stage.

You could also expand 1) to quotes from Spacex management, though I take those with a grain of salt. They have always claimed that reusability was a concern going way back.

But really we don't know.

[rpapo]

I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.

IIRC, this was one of the things they did with the F-1 engine.

[Lar]

I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.

IIRC, this was one of the things they did with the F-1 engine.

Which was, IMHO, an awesome engine for the day, and would still be a good engine today. I believe that it would have been possible to achieve reusability with at least some of the Saturn stages, if flight rates justified the investment.

(I may be even more of a "Saturn hugger" than I am a "Shuttle hugger")

[macpacheco]

True, we don't know, but we can infer that robustness is an important feature from two important facts:

1) Quotes from engineers expressing their frustration at Elon's insistence on extreme reliability. I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.

2) They increased the weight of the baffle between the engines. It does not make sense to take a payload hit to protect the engines from each other unless you plan on routinely flying in situations where you expect an engine could fail (flying the same engines multiple times, for example). You would not want an engine failure to ruin an otherwise reusable stage.

You could also expand 1) to quotes from Spacex management, though I take those with a grain of salt. They have always claimed that reusability was a concern going way back.

But really we don't know.

Elon is a perfectionist, won't settle for less, plus it's not like SpaceX has 30 years of rocket experience. So it's the wise thing to do, maybe they can engineer Raptor rockets with a little less extra margin. But given that's when reusability should start to happen in high volume, maybe should use the exact same margins.

It's not like F9R has a crappy payload, is too expensive, or some other bad consequence of an over-engineered rocket.

So this thread seem very out of touch with reality. Elon wants to do everything ULA can, he wants a rocket that stands a good chance of never ever loosing a primary payload, so that's the natural way to achieve that.

[Wigles]

True, we don't know, but we can infer that robustness is an important feature from two important facts:

1) Quotes from engineers expressing their frustration at Elon's insistence on extreme reliability. I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.

2) They increased the weight of the baffle between the engines. It does not make sense to take a payload hit to protect the engines from each other unless you plan on routinely flying in situations where you expect an engine could fail (flying the same engines multiple times, for example). You would not want an engine failure to ruin an otherwise reusable stage.

You could also expand 1) to quotes from Spacex management, though I take those with a grain of salt. They have always claimed that reusability was a concern going way back.

But really we don't know.

Elon is a perfectionist, won't settle for less, plus it's not like SpaceX has 30 years of rocket experience. So it's the wise thing to do, maybe they can engineer Raptor rockets with a little less extra margin. But given that's when reusability should start to happen in high volume, maybe should use the exact same margins.

It's not like F9R has a crappy payload, is too expensive, or some other bad consequence of an over-engineered rocket.

So this thread seem very out of touch with reality. Elon wants to do everything ULA can, he wants a rocket that stands a good chance of never ever loosing a primary payload, so that's the natural way to achieve that.

True, f9 doesnt have a crappy payload. But had it been designed as a single use it would have more. Designing an expendible means you arent limited by low cycle fatigue issues (pressurisation cycles etc). I am sure the large components that are difficult to change manufacturing processes are already designed for full reusability, but simple components or ones where it is easy to integrate a design change might have been left as less robust versions to be changed later when there was more flight data available.

[macpacheco]

True, f9 doesnt have a crappy payload. But had it been designed as a single use it would have more. Designing an expendible means you arent limited by low cycle fatigue issues (pressurisation cycles etc). I am sure the large components that are difficult to change manufacturing processes are already designed for full reusability, but simple components or ones where it is easy to integrate a design change might have been left as less robust versions to be changed later when there was more flight data available.

1 - Pressurization cycles ? That's aircraft stuff. Rocket's suffer from thermal and structural stresses, the only static pressure diferentials outside dragon are between the rp-1/lox tanks and the outside, and the critical areas of the rocket are more likely the combustion chamber, the turbopumps and the more critical structure areas of the rocket.
2 - Like I said, Elon doesn't want to risk having one catastrophic failure right in the process of proving F9R is an extremely reliable rocket, undoing all the good work.
So again, this idea doesn't make sense. SpaceX isn't interested in a rocket 99% reliable, they want a rocket that is at least 99.99% reliable, and that requires some level of over engineering, which makes the rocket a more natural fit for reusability.
Go ahead and speculate all you want... But I'm sure this is something he wouldn't compromise on, given F9R is already a very cost effective rocket, designed and built with methods conductive to very high scale for a rocket.

[Wigles]

But reliability for 1 launch is different to reliability for 100. It could be 99.99 for 1 launch but only 50 for a second depending on design. And when you are designing for minimum weight, all structural failure modes are important.
Aircraft stuff? How about fuel line pressurisation cycles, tanks, feederd, accumulators, helium tanks, low cycle thermal stresses, etc...

[mme]

But reliability for 1 launch is different to reliability for 100. It could be 99.99 for 1 launch but only 50 for a second depending on design. And when you are designing for minimum weight, all structural failure modes are important.
Aircraft stuff? How about fuel line pressurisation cycles, tanks, feederd, accumulators, helium tanks, low cycle thermal stresses, etc...

First of all, Elon Musk has publicly stated “We will never give up! Never! Reusability is one of the most important goals. If we become the biggest launch company in the world, making money hand over fist, but we’re still not reusable, I will consider us to have failed.” (see http://www.transterrestrial.com/?p=27574, and I've heard him say that in interviews.) Second, SpaceX clearly believes in constant, incremental, improvement. Third, they plan to put landing legs on the v1.1 because they believe they will be landing and reusing the v1.x version of the Falcon 9 soon. Finally, SpaceX has mentioned an eventual goal of $5-$7 million dollar launches and reusing a rocket a 100 times. That may be a pipe-dream, but that's their eventual goal and they are pushing to get there as fast as they safely can.

Therefore, the answer to the original question, "Was Falcon 9 1.1 overbuilt to support launch rates higher than needed?" is clearly "no." The Falcon 9 v1.1 is designed to be reliable, reusable, transport humans, and to the best of SpaceX's ability not fail catastrophically thereby losing a payload or killing people.

It makes no sense to use less robust parts when your goal is to be reusing it as soon as possible and you already are the least expensive LV actually flying. Doing so would add to the design complexity and not give you any data on the parts you intend to reuse.

[Wigles]

I agree that their goal might be to be fully reusable, but i doubt that they would intentionally hinder themselves upfront designing everything to be used 100 times when the first 10-20 over the first 10 years of flights will not be fully reusable.
Apple probably had the goal of making a colour multi purpose device with apps and a camera etc when they built the first ipod, but they didnt build this device initially because it would have been a massive cot and too expensive for the market.
I believe that there are elements of the f9 1.1 that are already reusable to a large degree but others may have required more data before being able to design them correctly. Nobody is building reusable launchers, they need to build the skills and technology incrementally.