Author Topic: Developing the BFS - Phase 1 Big Falcon Hopper (BFH) Discussion - THREAD 2  (Read 488089 times)

Offline eriblo

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[...]

su27k,
Minor correction. Raptors are O2 rich, mix is 3.8:1

Ned
It's late, but isn't stoichiometric 2 O2 : 1 CH4 = 2*2*15.999 u : 1*12.011 u + 1*4*1.008 u = 63.996 : 16.039 = 3.99 : 1 ?

And less oxygen than stoichiometric is fuel rich...?

Offline NH22077

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[...]

su27k,
Minor correction. Raptors are O2 rich, mix is 3.8:1

Ned
It's late, but isn't stoichiometric 2 O2 : 1 CH4 = 2*2*15.999 u : 1*12.011 u + 1*4*1.008 u = 63.996 : 16.039 = 3.99 : 1 ?

And less oxygen than stoichiometric is fuel rich...?
eriblo,
I am not a rocket engineer. I have read it many times in these forums. Here is one place, post 61.
https://forum.nasaspaceflight.com/index.php?topic=41363.60

Offline NH22077

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After more research, it is fuel rich. I have read it called oxygen rich many times. I think people are confused by the oxygen rich preburner. And I just repeated them, oops.

Ned
« Last Edit: 01/26/2019 11:01 pm by NH22077 »

Offline su27k

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[...]

su27k,
Minor correction. Raptors are O2 rich, mix is 3.8:1

Ned
It's late, but isn't stoichiometric 2 O2 : 1 CH4 = 2*2*15.999 u : 1*12.011 u + 1*4*1.008 u = 63.996 : 16.039 = 3.99 : 1 ?

And less oxygen than stoichiometric is fuel rich...?
eriblo,
I am not a rocket engineer. I have read it many times in these forums. Here is one place, post 61.
https://forum.nasaspaceflight.com/index.php?topic=41363.60

I think the mixture ratio changed in the 2017 version, a slide in the IAC 2017 presentation shows BFS has 240t methane vs 860t LOX, this is in the thread you referenced too: https://forum.nasaspaceflight.com/index.php?topic=41363.msg1728730#msg1728730

« Last Edit: 01/27/2019 03:10 am by su27k »

Offline rakaydos

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They should just fly it with that that dome as the top. Looks aerodynamic enough?

I've been thinking the same thing. Maybe they'll just pretty it up a bit and fly it the way it is.

The problem is when it does a hover-translation, those fin/legs are going to shuttlecock it pretty bad, meaning has to compansate with vectored thrust. The shiny foil cone, when moving sideways, is an airbrake that compensates or even reverses the effect.

Offline OxCartMark

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Its time to start building Hopper #2, the backup plan hopper.  Just do it!
Actulus Ferociter!

Offline ZChris13

Falcon 9 is always the same on the return, it weighs the same, has the weight in the same place, and is the same shape every time.
That won't be the case for Starship, in the case of weight and weight distribution. Interesting.

Offline OxCartMark

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They should just fly it with that that dome as the top. Looks aerodynamic enough?

I've been thinking the same thing. Maybe they'll just pretty it up a bit and fly it the way it is.

The problem is when it does a hover-translation, those fin/legs are going to shuttlecock it pretty bad, meaning has to compansate with vectored thrust. The shiny foil cone, when moving sideways, is an airbrake that compensates or even reverses the effect.
That's a much more ambitious test than I think anyone here has seriously proposed for the hopper before.  Not saying you're wrong or right but previously the thoughts around here have been up / down and a bit of horizontal divert, same as Grasshopper.
Actulus Ferociter!

Online Johnnyhinbos

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Scaffolding is going up around the Hopper.
That’s a lot of bottles they’ve staged next to the hopper base. Assume that’s for welding.
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline OxCartMark

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Scaffolding is going up around the Hopper.
Thatís a lot of bottles theyíve staged next to the hopper base. Assume thatís for welding.

I can't explain the position of the scaffolding on the outside of it but it seems to me its about time for a truck full of thrust structure plates to show up and be welded onto the bottom of the lowest tank dome using scaffolding under the thing.
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Offline OxCartMark

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Or perhaps after Caldwell they've hired a gang of brick masons to go up the scaffolding and put shuttle brick on the thing.
Actulus Ferociter!

Offline FutureMartian97

Scaffolding is going up around the Hopper.

Hope that scaffolding can take some wind. Doesn't look like it could take much...

Offline OxCartMark

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Or perhaps the scaffolding is to act as framework for an enclosure of plastic sheeting or tarp, said enclosure being either to create a (more) clean room environment for some upcoming steps or to allow a lot of welding to happen without the hassle of shield gas being blown off.  Based on the number of gas cylinders I'd lean toward seam welding of the skin plates.
Actulus Ferociter!

Offline alienmike

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I see a lot of wires going into the bottom of the hopper. I'm trying to see if there are spools of wire underneath, indicating that they are permanently wiring the hopper for data and power, or if this is just for power tools being used inside. Also, that is a lot of welding gas they have brought in...

Offline Wargrim

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They might weld up the shiny stainless steel panel borders that were previously only spotwelded.

Not sure what other exterior works remain. Possibly some piping/wiring that doesnt go through the tanks. Possibly some polishing/flattening of the panels.

[Edit]
Or even simpler, with the bottom getting filled up with Thrust structure/plumbing/engines, the outer scaffolding might just be a more convenient, practical and safer access to the manholes than taking a cherrypicker/crane each time.
[/Edit]
« Last Edit: 01/27/2019 06:19 pm by Wargrim »

Offline Nomadd

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 There will be welding the upper bulkhead from the outside and probably putting something for the upper section to attach to other than the few tabs they used the first time and maybe reinforcing the shiny stuff. Half a day assembling scaffolding is a whole lot better than juggling four cherry pickers for two weeks.
« Last Edit: 01/27/2019 07:51 pm by Nomadd »
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline NH22077

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[...]

su27k,
Minor correction. Raptors are O2 rich, mix is 3.8:1

Ned
It's late, but isn't stoichiometric 2 O2 : 1 CH4 = 2*2*15.999 u : 1*12.011 u + 1*4*1.008 u = 63.996 : 16.039 = 3.99 : 1 ?

And less oxygen than stoichiometric is fuel rich...?
eriblo,
I am not a rocket engineer. I have read it many times in these forums. Here is one place, post 61.
https://forum.nasaspaceflight.com/index.php?topic=41363.60

I think the mixture ratio changed in the 2017 version, a slide in the IAC 2017 presentation shows BFS has 240t methane vs 860t LOX, this is in the thread you referenced too: https://forum.nasaspaceflight.com/index.php?topic=41363.msg1728730#msg1728730

Ok, I stand corrected.

Ned

Offline Wolfram66

Scaffolding is going up around the Hopper.
Thatís a lot of bottles theyíve staged next to the hopper base. Assume thatís for welding.

Can you explain the color codes for the bottles? Green is Oxygen I think

Offline Rei

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Unrelated to oxygen: with the scaffolding going up around the hopper... I presume that means they're getting ready to turn those tacks into proper welds?

Offline Scylla

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Scaffolding is going up around the Hopper.
Thatís a lot of bottles theyíve staged next to the hopper base. Assume thatís for welding.

Can you explain the color codes for the bottles? Green is Oxygen I think
Unfortunately, cylinder color has no standard across jurisdictions and is often unregulated. The only way to know what is in a bottle is to read the tag on the bottle. I have often seen oxygen in green bottles, but not always.
I reject your reality and substitute my own--Doctor Who

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