Discussion Elon Musk: the F9 first stage can reach orbit as an SSTO.

[Urwumpe]

It has been argued that SpaceX didn't exactly do any ground breaking work on a "new" rocket motor, it's essentially old tech on a modern production line. There's a whole thread somewhere on the forum offering plenty of criticism over the whole thing.http://www.fireflyspace.com/

Also a lot of modern technology included cheaply by having modern production lines - the 3.something percent inert mass ratio is not achieved by aluminum alone, they are also doing state of the aerospace industry grade lightweight structures there.

Which is the important difference there: They are not relying on magic, not on untested theories.

 

[PhantomCruiser]

Yeah I meant to add metallurgy to my comment. And 3D printing, that's pretty cool. I'd like to see some of their NDI data. Between engines and main-mounts I spent many hours with dye penetrant and fluoroscope. This helped me get my current job too!

 

[RGClark]

You have? How? You have not even yet understood how altitude compensation works at the most abstract level, without any mathematical models. How did you calculate any performance value that is not worse than rolling dices? Do you even know the basic formula how to estimate the specific impulse of an ideal rocket engine right at the altitude it was optimized for?

Ok, show me. DO the calculation. Give the correct amount for the payload.

Bob Clark

 

[PhantomCruiser]

I think you are missing the point. We are not your students in a lecture hall. I/we have nothing to prove to you.

You have the title "Mathemetician" under your moniker. You show us. Prove your argument.

 

[Urwumpe]

Ok, show me. DO the calculation. Give the correct amount for the payload.

Bob Clark

You claim, you prove. Ever heard of scientific method?

When you claim or assume something, you either prove it in your own paper as your own work, or you cite somebody. If you construct circular references like your infamous "Blog post A is correct because of blog post B, which is correct because of blog post A", yes, I pay attention to such details, don't be surprised if people are not convinced.

Also, your question was, if a SpaceX Falcon 9 1.2 first stage can be used as expendable SSTO. Since not much data of a Falcon 9 is known to the public, I reconstructed a model of the Falcon 9 and then calculated the SSTO performance, and showed that it has only a subpercent payload mass ratio, which is a strong hint that more detailled calculations will not show a significant change. Also expending a 450 ton SSTO for the payload capacity of a much smaller and cheaper launcher (For example Epsilon) is sure not advancing mankind into space.

So, I had done more right now with just three hours of finding initial conditions, programming a genetic optimization algorithm and estimating the SSTO performance of the most suitable configuration, than you have done so far in the past months. You are highly in my debt now and demanding more from my side is only a sign of your dishonor and disrespect.

Also, what is the correct amount of payload? :lol:

I can of course do a second or third level calculation of the candidates. I can also include different engines and even largely risky technology like aerospikes. But that would mean far more work than just three hours of my life for a question, that is not mine. If the work will exceed 8 hours of my life, you won't find it here in the forum, but in a scientific journal that I can afford. :lol:

 

[RGClark]

It's a free internet, bud. Do as you will.

Bob Clark

 

[ADSWNJ]

/thread please mods

 

[orbitingpluto]

It wasn't literally ALL. It was only, say, 99.9%. And among them included some of the greatest intellects of the time. That is why these far more experienced even more brilliant scientists couldn't see how to do it. Because they already believed it couldn't be done.

Bull feces. If such a majority of learned people existed at the time, Octave Chanute wouldn't have had articles published in The Railroad and Engineering Journal, and Samuel Pierpont Langley wouldn't have gotten an audience at the War Department or the Smithsonian for his Aerodrome. Both men were firmly established in sober fields, Chanute being a railroad engineer and Langley a astronomer, and neither had their career or reputations damaged by getting involved with aviation. You are blindly asserting that 99.99% number because it suits a narrative convenient for your purposes.

Now, we have the heads of billion dollar aerospace companies with billion dollar launch contracts having to be dragged kicking and screaming to the idea reusable vehicles can cut launch costs. And they are being led there by a newcomer to the industry, not someone with decades of experience in the field.

There is a difference between "we won't do this because it is impossible" and "we won't do this because it would be stupidly expensive". Building or redesigning a rocket to be reusable takes larger coffers of cash than a expendable one, and should it not work, a company would be stuck recouping the cost of development while flying the rocket in expendable mode. That's why launch companies were, and still to some extent are, leery of getting deep into reusablity. Even SpaceX has worked in cautious steps, trying to keep from biting off too much at one time.

On the second thing, you might not know that it's mostly Mr Musk's personal emphasis on lower launch costs that SpaceX is spending time and dollars on reusabilty, not because he or his employees see something that the more established companies missed. It's also Mr Musk's fortune that allows SpaceX the capital to do the development that they do and take risks; a different company would have to plan on reinvesting profits in development or getting a loan from a bank or subsidy from a government to achieve something similar, and any route is fraught with potential complications and risks, on top of the potential complications and risks of reusable rocket development.

As Arthur C. Clarke famously said, "When a distinguished but elderly scientist says something is possible, he is very probably right. When a distinguished but elderly scientist says something is impossible, he is very probably wrong."

Bob Clark

Your quite reminded me of this one by the same man:
"The Information Age offers much to mankind, and I would like to think that we will rise to the challenges it presents. But it is vital to remember that information — in the sense of raw data — is not knowledge, that knowledge is not wisdom, and that wisdom is not foresight. But information is the first essential step to all of these." Arthur C Clarke

 

[Ravenous]

As Arthur C. Clarke famously said, "When a distinguished but elderly scientist says..."

My version:

Bumper Sticker quotes from distinguished authors does not constitute an argument.

If ACC were here telling everyone about SSTOs with whatever features you're talking about, he would have shown us his working by now (and possibly even a very rough design idea). He knew what he was talking about, and when he didn't know he admitted it and made sure he found out.