Author Topic: The Reaction Engines Skylon Master Thread (5)  (Read 441512 times)

Online pippin

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1120 on: 12/26/2015 09:06 AM »
The "how does SpaceX compare to Skylon" discussion was relevant.
The "does Elon ever have to change plan" discussion is not (here).

Online john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1121 on: 12/27/2015 07:08 AM »
The "how does SpaceX compare to Skylon" discussion was relevant.
The "does Elon ever have to change plan" discussion is not (here).
You're confusing SpaceX (the company) with Skylon (the vehicle)

But actually SX's changes of plan are very relevant to how these business differ.

SX has followed a fairly common Silicon Valley paradigm.

1)Create the system/software/whatever up to the difficult part
2)Hope that by then we've learned enough to figure a way to make the difficult part work
3)If we have, do it.
4)If not revise what we want to do or try and sell what we've got as it is.

REL's approach has been.
What is the vehicle needed to meet this market goal.
Work backward to find the engineering that can implement it.

One is bottom up, one is top down.

The difference is one delivers a working system early (IE an ELV) but might never deliver its ultimate goal. The 2nd delivers a working system at the end that will meet the end goal.

The first is a "bottom up" approach where the company "feels" it's way to it's goal. The second starts iwth the map and works out how to get the pieces needed to get there.

SX have built a superb ELV but Musk is adamant there will be no 2nd stage reuse. That's not an Apples to Apples comparison with Skylon. 

If you'd like a fair comparison between a true F9R and Skylon you'd have to

a)Give the F9 a reusable or "tug" stage like the SUS
b)Limit the F9 2nd stage to just need to get its payloads to LEO.
c)Make the 2nd stage survive and be reusable to the same planned limits as the 1st stage
d)Increase it's payload to LEO by about 1800Kg.
e)Allow the whole package to be purchased (and operated) by anyone not on the UN banned list.

That would make a true F9R a very interesting development in both the technical and the economic areas and might lower the normal cost / Kg by quite a lot, which is my key interest.
« Last Edit: 12/27/2015 07:10 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online pippin

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1122 on: 12/27/2015 08:37 AM »
If you want a fair comparison Skylon first would have to fly.
And in a "Silicon Valley" approach you don't have a goal that you could reach or not reach, you just have a vision. That's a difference.

Offline Paul451

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1123 on: 12/27/2015 09:52 AM »
Getting a first stage of a 2 stage vehicle down is an amazing achievement, but (provided it can be re-flown) it's still half of a reusable rocket.

9 engines recovered out of ten. 80% of dry mass recovered.

But "half".

Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft.

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1124 on: 12/27/2015 11:56 AM »
If you want a fair comparison Skylon first would have to fly.
Definitely.
Quote
And in a "Silicon Valley" approach you don't have a goal that you could reach or not reach,
And hence a point at which investors can say you've succeeded or failed.   :)
Quote
you just have a vision. That's a difference.
I think you're confused by what that word means.

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary.

Building a cheaper ELV? That's seems like the goal of every other aerospace startup since the 1980's.

Recovering and reusing the 1st stage? Every major aerospace contractor was talking about this in the 1960's and has been claiming they could do it (with enough funding of course  ;) ) ever since.  Implementing that goal has taken some ground breaking science and engineering.

Now Musk's ultimate goal, persuading a significant number of people to emigrate to Mars (and getting them to pay their way to do so  :) ), is visionary.

9 engines recovered out of ten. 80% of dry mass recovered.

But "half".
Economically it's more than 50% but operationally it's simply 1 stage of 2. With no chance of recovery of the 2nd, which will have to be replaced, versus a system where what goes up comes back down.
Quote
Changing the definition of a word to have a more limited meaning borrows from another Silicon Valley company, Microsoft.
Again semi reusable is not reusable.  Fully reusable is reusable.

I look forward to seeing SX's plans for the BFR, which they are now saying will be fully reusable.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline NovaSilisko

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1125 on: 12/27/2015 06:01 PM »
THIS THREAD IS NOT ABOUT SPACEx!

Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1126 on: 12/28/2015 01:48 AM »
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). Nothing about a HTOL vehicle prototype, let alone one near SSTO performance.

...additionally, Skylon is practically TSTO anyway, since almost all commercial payloads of note are GSO.

Lots of people have had ideas for RLVs, even SSTO and horizontally landing ones. So far, Skylon isn't even as far as X-33, nor do I see evidence that they'll get that far.

Europe, please prove me wrong.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Lars-J

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1127 on: 12/28/2015 05:03 AM »

SX has followed a fairly common Silicon Valley paradigm.

1)Create the system/software/whatever up to the difficult part
2)Hope that by then we've learned enough to figure a way to make the difficult part work
3)If we have, do it.
4)If not revise what we want to do or try and sell what we've got as it is.

REL's approach has been.
What is the vehicle needed to meet this market goal.
Work backward to find the engineering that can implement it.

One is bottom up, one is top down.

The difference is one delivers a working system early (IE an ELV) but might never deliver its ultimate goal. The 2nd delivers a working system at the end that will meet the end goal.

I see what you did there. :) So there is no risk at all in the 2nd approach? You forgot to add this: ... But it might never deliver anything at all.

But if that really is your opinion, then it explains a great deal about your cheerleading for Skylon.

Online john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1128 on: 12/28/2015 06:08 AM »
I see what you did there. :) So there is no risk at all in the 2nd approach? You forgot to add this: ... But it might never deliver anything at all.
You seem to have a very short memory.

I've repeatedly stated that SABRESkylon is a high risk/cost/reward project. 

Why would expect something the size of Airbus A380 to be less to build than A380?
Quote
But if that really is your opinion, then it explains a great deal about your cheerleading for Skylon.
Why don't you explain "my opinion" to me. I'd love to see the outsiders view.
« Last Edit: 12/29/2015 06:31 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline t43562

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1129 on: 12/28/2015 02:19 PM »
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). ....

They do need their heat exchanger even in their new design - they simply won't need to drop the temperature as much if they use SABRE4  and therefore won't need the anti-freeze system.  It's difficult to discuss when basic inaccuracies keep slipping in.


Offline Robotbeat

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1130 on: 12/29/2015 02:38 AM »
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level) and a heat exchanger (which I'm told they don't even need for their new design). ....

They do need their heat exchanger even in their new design - they simply won't need to drop the temperature as much if they use SABRE4  and therefore won't need the anti-freeze system.  It's difficult to discuss when basic inaccuracies keep slipping in.
I appreciate the correction, but the essence of what I meant stands: I remember a big deal being made of their fancy demoed heat exchanger that can prevent icing, but you say now it's not needed.

Just skepticism. I've seen too many things that are studied to death or a few low-level tests and then nothing. I want them to actually BUILD a vehicle. I like the idea of their battleship demo vehicle that I heard here. Anything like that would be better than now.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1131 on: 12/29/2015 06:29 AM »
I appreciate the correction, but the essence of what I meant stands: I remember a big deal being made of their fancy demoed heat exchanger that can prevent icing, but you say now it's not needed.
Your memory needs a little correction. The big deal about the REL HX technology is twofold It does not clog with ice (which they tested) and it's phenomenal power to weight ratio (IE power extracted from the airflow), which AFAIK they've also tested since the test unit was a full size module of the SABRE design.

The equivalent capacity HX used by nuclear power stations (such as the ones on the Nimitz class carriers for example, where weight is a factor) weigh 200 tonnes.

That's a 100-200:1 improvement.
Quote
Just skepticism. I've seen too many things that are studied to death or a few low-level tests and then nothing. I want them to actually BUILD a vehicle. I like the idea of their battleship demo vehicle that I heard here. Anything like that would be better than now.
Then we're all in complete agreement.  :)
« Last Edit: 12/29/2015 06:32 AM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Kharkov

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1132 on: 12/29/2015 07:10 AM »
...

Believing we are close to being able to build a vehicle that can do HTOL SSTO (when the "smart" money says VTO TSTO is the safe way to go) and pursuing it is visionary....
...who is pursuing it with whose army? I just see some R&D money, a few battleship pressure-fed rocket engine tests (not much more than amateur level)... (snip)
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.

"...a few battleship pressure-fed rocket engine tests..."?

I hope this isn't out of turn but could somebody explain that last bit?
Even Entropy Isn't What It Used To Be

Online john smith 19

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1133 on: 12/29/2015 07:45 AM »
I'm sorry, I've been doing my best to follow this thread but I think I missed a turn there.

"...a few battleship pressure-fed rocket engine tests..."?

I hope this isn't out of turn but could somebody explain that last bit?
he's referring to the series of uncooled engines REL have used to refine their design. These have typically been made from solid lumps of metal and are therefor quite heavy. Hence the term "battleship," as opposed to "flight weight."
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline RanulfC

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1134 on: 12/29/2015 05:44 PM »
Or a rocket powered Battleship! Lets face it that HAS to have some 'cool-is-the-rule' points :)

Randy
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Offline Jim

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1135 on: 12/29/2015 08:21 PM »

The question is how big a threat of leakage does a satellite pose if adequately sealed and how do other operators deal with these problem?


They are never "sealed".  There is always a chance of a leak.  The mitigation is to limit personnel exposure.  Only those necessary in performing work on the vehicle are allowed near the vehicle.  Hence, there are no offices facilities containing spacecraft loaded with propellants.

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1136 on: 12/29/2015 10:25 PM »
Or a rocket powered Battleship! Lets face it that HAS to have some 'cool-is-the-rule' points :)

Randy
Oh that's Niven and Pournell's "Footfall."  :)
« Last Edit: 12/29/2015 10:25 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline francesco nicoli

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1137 on: 01/01/2016 10:10 AM »
So, with SpaceX demonstrating first stage return and soon performing a static fire test with zero extra refurbishment, can we call the reusability space race on?

this has implications for Skylon. Huge implications, I believe: it is the only design out there which could compete, in the long run, with spaceX. Wouldn't you look at it if you were in the governing body of some classical launching providers starting to feel the heat?

(happy new year to all!)

Offline flymetothemoon

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1138 on: 01/01/2016 01:06 PM »
So, with SpaceX demonstrating first stage return and soon performing a static fire test with zero extra refurbishment, can we call the reusability space race on?

this has implications for Skylon. Huge implications, I believe: it is the only design out there which could compete, in the long run, with spaceX. Wouldn't you look at it if you were in the governing body of some classical launching providers starting to feel the heat?

(happy new year to all!)

Sadly I seem to have learned form all this that the only re-usability private might be willing to fund is 'doing something like SpaceX'.  Is it realistically only the U.S. or Europe (govt agencies) who might take it further on the grounds that it is important new technology to be developed for all - or technology that would give an edge?

Offline QuantumG

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Re: The Reaction Engines Skylon Master Thread (5)
« Reply #1139 on: 01/01/2016 10:08 PM »
Nah, there's plenty of money available for a venture like this.. you just have to come up with a business plan that scales. There's a reason why there's a dozen different smallsat launch startups.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

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