Author Topic: Many smaller sized Raptor engines on future BFR's?  (Read 11851 times)

Offline OneSpeed

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #100 on: 09/21/2017 01:23 PM »
Where can I get that "Nozzle Pack" software? Google isn't being particularly helpful in this case.

NozzlePack is just a C# tool I wrote for myself, but if anyone else finds it useful, that's great. I've recently updated it in an attempt to make it more user friendly. The attached zipfile contains the program, a config file, and two directories containing .xml configuration files for rockets and engines. E.g. here are the file contents for the Falcon S1:

F9S1.xml:
<?xml version="1.0" encoding="utf-8" ?>
<danceFloor>
  <diameter>3.66</diameter>
  <engines>
    <circle>
      <name>Merlin1D</name>
      <radius>0</radius>
      <count>1</count>
      <offset>0.125</offset>
    </circle>
    <circle>
      <name>Merlin1D</name>
      <radius>1.35</radius>
      <count>8</count>
      <offset>0.125</offset>
    </circle>
  </engines>
</danceFloor>

Merlin1D.xml:
<?xml version="1.0" encoding="utf-8" ?>
<diameters>
  <bell>0.89</bell>
  <chamber>0.3</chamber>
  <throat>0.178</throat>
</diameters>

When you run the program, go to File/Load and select the rocket configuration file you are interested in.
I've include F9S1, F9S2, BFR, BFS and New Glenn as starters, but you can copy them and create your own.
You'll need MS Windows with the .NET Framework 4.5.2, which is a free download here: https://www.microsoft.com/en-au/download/details.aspx?id=42643

Offline rsdavis9

Re: Many smaller sized Raptor engines on future BFR's?
« Reply #101 on: 09/21/2017 02:47 PM »
Has anybody considered that instead of individual TVC for each engine that the whole rocket could be steered with differential thrust?
So for example with the falcon 9 get rid of TVC and use differential thrust on different engines around the ring of engines on the outside of the rocket.
Still might have a problem with roll but that could be solved by making the outer ring slightly pointed right then left as you go around the ring and just applying different thrust to the odd or even engines.
For landing you probably want one engine with TVC.

It could save a lot of weight.
With lots of engines I would expect finer control of the vector.
Should be a greater vector with larger diameter rockets.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Online TrevorMonty

Re: Many smaller sized Raptor engines on future BFR's?
« Reply #102 on: 09/21/2017 05:42 PM »
Things can be done in parallel. You don't have to wait for the engines to pass qualification before you design the rest of the booster.
True but the engine needs to have completed some test fires. In case of full scale Raptor we've not heard of any being tested.

Online Peter.Colin

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #103 on: 09/21/2017 05:51 PM »
Thinking about the proportionality of rockets and rocket engines made me wonder about the following:
 
Would it have been easier to colonize mars if the human species was smaller than it is now, or bigger than it is now?
Or are we ourselves as a humans at 1,80 meter coincidently at the optimal size to build similar sized rockets engines and become a space fairing civilization?

If we where smaller we might have built smaller rocket engines with higher T/W or build the exact same “optimal” engine size as we do now, but less of them where needed, to get 100 people to Mars. Or if we would have been bigger than now, we would be able to build large engines more easily, but maybe get in trouble with material properties not being sufficient. The only option then would be to get many small engines on a large rocket.

And what size would an alien space fairing civilization be, if compared to our own size?

« Last Edit: 09/21/2017 06:34 PM by Peter.Colin »

Offline envy887

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #104 on: 09/21/2017 06:35 PM »
Has anybody considered that instead of individual TVC for each engine that the whole rocket could be steered with differential thrust?
So for example with the falcon 9 get rid of TVC and use differential thrust on different engines around the ring of engines on the outside of the rocket.
Still might have a problem with roll but that could be solved by making the outer ring slightly pointed right then left as you go around the ring and just applying different thrust to the odd or even engines.
For landing you probably want one engine with TVC.

It could save a lot of weight.
With lots of engines I would expect finer control of the vector.
Should be a greater vector with larger diameter rockets.

Last year's ITS booster was presented with rings of differential thrusting non-gimballing engines surrounding a TVC gimballed central cluster. Dragon 2 uses differential thrust steering for the abort motors. And N-1's booster used differential thrust for steering.
« Last Edit: 09/21/2017 06:35 PM by envy887 »

Offline rsdavis9

Re: Many smaller sized Raptor engines on future BFR's?
« Reply #105 on: 09/21/2017 06:56 PM »
Has anybody considered that instead of individual TVC for each engine that the whole rocket could be steered with differential thrust?
So for example with the falcon 9 get rid of TVC and use differential thrust on different engines around the ring of engines on the outside of the rocket.
Still might have a problem with roll but that could be solved by making the outer ring slightly pointed right then left as you go around the ring and just applying different thrust to the odd or even engines.
For landing you probably want one engine with TVC.

It could save a lot of weight.
With lots of engines I would expect finer control of the vector.
Should be a greater vector with larger diameter rockets.

Last year's ITS booster was presented with rings of differential thrusting non-gimballing engines surrounding a TVC gimballed central cluster. Dragon 2 uses differential thrust steering for the abort motors. And N-1's booster used differential thrust for steering.

So why even bother with the center TVC gimballing? Only for landing?
If you could get rid if the TVC system completely that would eliminate some weight...
 
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Online yokem55

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #106 on: 09/21/2017 07:02 PM »
Thinking about the proportionality of rockets and rocket engines made me wonder about the following:
 
Would it have been easier to colonize mars if the human species was smaller than it is now, or bigger than it is now?
Or are we ourselves as a humans at 1,80 meter coincidently at the optimal size to build similar sized rockets engines and become a space fairing civilization?

If we where smaller we might have built smaller rocket engines with higher T/W or build the exact same “optimal” engine size as we do now, but less of them where needed, to get 100 people to Mars. Or if we would have been bigger than now, we would be able to build large engines more easily, but maybe get in trouble with material properties not being sufficient. The only option then would be to get many small engines on a large rocket.

And what size would an alien space fairing civilization be, if compared to our own size?
Throttle levels are much slower to respond and less precise than hydraulic TVC. Whether differential throttling could be fast  or precise enough I think is unlikely.

Online jpo234

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #107 on: 09/21/2017 07:28 PM »
Things can be done in parallel. You don't have to wait for the engines to pass qualification before you design the rest of the booster.
True but the engine needs to have completed some test fires. In case of full scale Raptor we've not heard of any being tested.

Why? You actually need a working exemplar is, when you assemble the first booster. You can and have to do a lot of design work before that happens.
Best example is Blue: The New Glenn design is obviously fairly advanced and yet a complete BE-4 hasn't even been test fired on the stand.
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline envy887

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #108 on: 09/21/2017 07:52 PM »
Thinking about the proportionality of rockets and rocket engines made me wonder about the following:
 
Would it have been easier to colonize mars if the human species was smaller than it is now, or bigger than it is now?
Or are we ourselves as a humans at 1,80 meter coincidently at the optimal size to build similar sized rockets engines and become a space fairing civilization?

If we where smaller we might have built smaller rocket engines with higher T/W or build the exact same “optimal” engine size as we do now, but less of them where needed, to get 100 people to Mars. Or if we would have been bigger than now, we would be able to build large engines more easily, but maybe get in trouble with material properties not being sufficient. The only option then would be to get many small engines on a large rocket.

And what size would an alien space fairing civilization be, if compared to our own size?
Throttle levels are much slower to respond and less precise than hydraulic TVC. Whether differential throttling could be fast  or precise enough I think is unlikely.
This, and it has less control torque than a typical gimbal setup.

Online Peter.Colin

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #109 on: 09/29/2017 10:33 PM »
After seeing the presentation today, I feel like the new size and new design of the BFR makes it a perfect multi utility workhorse.
It could be in service for a long time before the next BFR will be realized.
What size would make this one seem like a rowboat, as Musk said the 12 meter would seem in the future.
And is a bigger size even nescerry?
« Last Edit: 09/29/2017 10:33 PM by Peter.Colin »

Online wannamoonbase

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #110 on: 09/29/2017 10:36 PM »
After seeing the presentation today, I feel like the new size and new design of the BFR makes it a perfect multi utility workhorse.
It could be in service for a long time before the next BFR will be realized.
What size would make this one seem like a rowboat, as Musk said the 12 meter would seem in the future.
And is a bigger size even nescerry?

I think that if this BFR actually gets built and flies that it's the larger BFR doesn't get built. 

A 12 million Lbf rocket, is not a small rocket, this could do a ton of work.
Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline rakaydos

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #111 on: 09/30/2017 12:22 AM »
After seeing the presentation today, I feel like the new size and new design of the BFR makes it a perfect multi utility workhorse.
It could be in service for a long time before the next BFR will be realized.
What size would make this one seem like a rowboat, as Musk said the 12 meter would seem in the future.
And is a bigger size even nescerry?

I think that if this BFR actually gets built and flies that it's the larger BFR doesn't get built. 

A 12 million Lbf rocket, is not a small rocket, this could do a ton of work.
I disagree. Once we start developing Ceres and beyond, a Nova-class rocket isnt going to cut it- we'll need a (non-nuclear) Orion class for the really big space construction.

But that might not be an EARTH lift vehical, if we can manufacture it on a lighter celestial body, like a moon base.

Online Peter.Colin

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Re: Many smaller sized Raptor engines on future BFR's?
« Reply #112 on: 09/30/2017 07:19 AM »
We might draw parallels on the current Earth transport system.
If the “Falcon 31” is like the semi truck and it could contain one stackable container.
We could have a really big container ship for plannet to plannet transport, maybe with a different kind of propulsion. This container ship stays in space (stays in the sea), and the containers are offloaded again by Falcon 31 Spaceships on for instance Mars.

However not everything fits in a container, heavy mining equipment, bulldozers, parts of chemical plants, large spaceship bulkheads, huge vessels etc etc.
There could be a real need for a bigger “Falcon X” (Bigger Falcon Rocket version x,x presented at IAC 20xx)
Also Elon Musk explaned yesterday that the living conditions are quite suitable for this first BFS, implying there will be a next probably bigger one.

I do think there is no real physics determined size limit to the large cargo spaceship that stays in orbit.
But for the Falcon X there probably are some physics determined size limits, like rocket height.
I do believe physics would allow the rocket diameter to be at least 10 times bigger.
But maximum height maybe only twice as high, since one engine can only lift a certain collumn of rocket wheigt above it.



« Last Edit: 09/30/2017 09:57 AM by Peter.Colin »

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