Author Topic: Developing the BFS - Phase 1 Big Falcon Hopper (BFH) Discussion - THREAD 2 (Read 502583 times)

eriblo · « **Reply #1240 on:** 01/26/2019 09:32 pm »

Quote from: NH22077 on 01/26/2019 08:23 pm

[...]

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...?

NH22077 · « **Reply #1241 on:** 01/26/2019 10:46 pm »

Quote from: eriblo on 01/26/2019 09:32 pm

Quote from: NH22077 on 01/26/2019 08:23 pm
[...]

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

NH22077 · « **Reply #1242 on:** 01/26/2019 11:00 pm »

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

su27k · « **Reply #1243 on:** 01/27/2019 03:09 am »

Quote from: NH22077 on 01/26/2019 10:46 pm

Quote from: eriblo on 01/26/2019 09:32 pm
Quote from: NH22077 on 01/26/2019 08:23 pm
[...]

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

rakaydos · « **Reply #1244 on:** 01/27/2019 01:38 pm »

Quote from: flyright on 01/26/2019 05:43 pm

Quote from: frostbit_canadian on 01/26/2019 02:02 pm
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.

OxCartMark · « **Reply #1245 on:** 01/27/2019 03:16 pm »

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

ZChris13 · « **Reply #1246 on:** 01/27/2019 03:16 pm »

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.

OxCartMark · « **Reply #1247 on:** 01/27/2019 03:20 pm »

Quote from: rakaydos on 01/27/2019 01:38 pm

Quote from: flyright on 01/26/2019 05:43 pm
Quote from: frostbit_canadian on 01/26/2019 02:02 pm
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.

Johnnyhinbos · « **Reply #1248 on:** 01/27/2019 04:31 pm »

Quote from: bocachicagal on 01/27/2019 04:27 pm

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.

OxCartMark · « **Reply #1249 on:** 01/27/2019 04:57 pm »

Quote from: Johnnyhinbos on 01/27/2019 04:31 pm

Quote from: bocachicagal on 01/27/2019 04:27 pm
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.

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.

OxCartMark · « **Reply #1250 on:** 01/27/2019 04:59 pm »

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

FutureMartian97 · « **Reply #1251 on:** 01/27/2019 05:20 pm »

Quote from: bocachicagal on 01/27/2019 04:27 pm

Scaffolding is going up around the Hopper.

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

OxCartMark · « **Reply #1252 on:** 01/27/2019 05:32 pm »

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.

alienmike · « **Reply #1253 on:** 01/27/2019 06:04 pm »

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...

Wargrim · « **Reply #1254 on:** 01/27/2019 06:14 pm »

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]

Nomadd · « **Reply #1255 on:** 01/27/2019 07:46 pm »

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.

NH22077 · « **Reply #1256 on:** 01/27/2019 07:51 pm »

Quote from: su27k on 01/27/2019 03:09 am

Quote from: NH22077 on 01/26/2019 10:46 pm
Quote from: eriblo on 01/26/2019 09:32 pm
Quote from: NH22077 on 01/26/2019 08:23 pm
[...]

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

Wolfram66 · « **Reply #1257 on:** 01/27/2019 10:37 pm »

Quote from: Johnnyhinbos on 01/27/2019 04:31 pm

Quote from: bocachicagal on 01/27/2019 04:27 pm
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.

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

Rei · « **Reply #1258 on:** 01/27/2019 10:48 pm »

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?

Scylla · « **Reply #1259 on:** 01/27/2019 10:54 pm »

Quote from: Wolfram66 on 01/27/2019 10:37 pm

Quote from: Johnnyhinbos on 01/27/2019 04:31 pm
Quote from: bocachicagal on 01/27/2019 04:27 pm
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.

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.