Author Topic: Developing the BFS - Phase 1 Big Falcon Hopper (BFH) Discussion - THREAD 1 (Read 652360 times)

OxCartMark · « **Reply #640 on:** 12/31/2018 05:31 pm »

My position:

The rings are just rings to be added to the tinfoil hat. Not to be slipped into the water tower. Not tanks. Just more of the same, middle rings. Its easier to work on them when they're closer to the ground than to stack the whole of the tinfoil hat and then do everything from a platform in the sky. The tinfoil hat is either for visual appeal when Elon stands in front of it and makes his presentation and tries to enlist everyone's support for the great endeavor or perhaps more sportingly it may have the pressure bulkhead added at one end, be fully seam welded, and puffed up to be able to handle some amount of flight load (which I tend to think will happen). I lean toward some form of F9 tanks or something like a shortened Raptorized F9 first stage being inserted into it. Or perhaps some field made tanks. I don't think that the industrial storage tanks nearby are going to fly, there's just too many problems with that, standing them on end, fill / drain / vent in the wrong place, mounts in the wrong place, outlet too small for flow rate.

If it does turn out that these sections are just adding to the length of the cylinder that is the bottom portion of the tinfoil hat it seems to me that a better way to form that cylinder would be to lay strips of stainless sheet in parallel on a large concrete slab and weld them on the floor then ratchet strap the edges together to form a ring (weld).

If it were me having accumulated this army of workers and gobs of rental equipment, being on a roll, knowing that you're likely to turn the hopper into scrap metal or an unplanned artificial reef, and not wanting the schedule delay that would cause I'd be making another one in immediate succession. Either another same or another enhanced (longer build time with some nice to have features that didn't get into the first one) or a mini-Superheavy or a more # engines version.

Johnnyhinbos · « **Reply #641 on:** 12/31/2018 05:32 pm »

Quote from: Barrie on 12/31/2018 05:15 pm

Quote from: Johnnyhinbos on 12/31/2018 04:48 pm
Once again - these top sections are only rebar and foil metal spot welded in place. It's NOT structural, it's NOT built for holding pressure, it's simply shape. This early iteration (Phase I) of the BFH is once again a mass / shape simulator to test out the engines/thrust frame/avionics in atmospheric testing.

No esoterics (beyond the engines). Tanks will be small and off the shelf (most likely). Think KISS, think agile, think Phase I.

The more advanced stuff can come later.

Yes to everything, but I'm still thinking of F9 tanks as off-the-shelf. Now we know the fairing is going even higher, it is becoming more plausible that 1st stage tanks (tanks only, nothing else) might fit, but I take your point about relative fragility. I can't see a long thin tank, with maybe the bottom third stuck in the airframe like a fence-post, being robust enough. I still think we might see an upper stage tank turn up $:-\$ We shall see

I like the idea - however my concern is that I believe these tanks need to be pressurized to aid in structural rigidity. I have a feeling this beast will be a bit, er, clunky during landing. I also don't know if a F9 booster tank setup designed for RP1/LOX would work for methane/LOX.

Finally, if they do go with a F9 then perhaps an upper stage setup would be a better choice? 3 Raptors firing for a few minutes - consume how much (asking, no idea).

jpo234 · « **Reply #642 on:** 12/31/2018 05:34 pm »

Quote from: bocachicagal on 12/31/2018 05:31 pm

I hope you all wanted more pictures!

Ok. So they won't lift it back onto the base.

Lars-J · « **Reply #643 on:** 12/31/2018 05:36 pm »

Quote from: bocachicagal on 12/31/2018 05:31 pm

I hope you all wanted more pictures!

Well, they are certainly 3 in one line, just as I predicted.

But are they actual Raptors or placeholder mock-ups to test out initial ground ops? They lack any defining features...
EDIT: Looking closer - their alignment looks a little bit off, so I suspect they are just steel engine nozzles for fit checks. But I have been wrong before!

meekGee · « **Reply #644 on:** 12/31/2018 05:39 pm »

Quote from: bocachicagal on 12/31/2018 05:31 pm

I hope you all wanted more pictures!

Haha was it three days ago that someone figured it's take several weeks to get the thrust structure and engines in place?

DistantTemple · « **Reply #645 on:** 12/31/2018 05:41 pm »

ISTM that there is a long string of errors above, in the last two pages. However I may be proved wrong in at least a few places.
As I see it, the foil sections are the outside of the upper part of the ship, and the heavy stainless tank is the outside of the base. Nothing will slide inside anything else, apart from possibly a tiny overlap. I don't think there will be any extra layer inside or out side of what we see. All the pieces will be stacked vertically. There will be no double skin.

The dome sections are to go inside the base making a fake, but structural bottom of the spaceship, to take the engine mountings and thrust, in a similar way to the planned final Starship. This is because this is part of what they are testing, and is naturally a very strong shape and excellent for spreading the thrust forces without distortion, also engine mounting geometry and actuators will be able to approximate the real design, give more validity to data points acquired.

The "foil" (actually probably thin sheet not foil at all) sections are not structural and are mainly for show, (It will be absolutely stunning to see this thing fly, it will be all over the worldwide press, change perceptions - and make it easier to raise funding) and maybe to be slightly realistic for lateral air resistance if the hopper rolls, or transits... although I doubt that ...

The term balloon tanks does not apply to this vehicle, but the later iterations, where the tank will be structurally part of the ship, which is not the case here. The foil top could not contain more than a few psi, (although the care now being taken to cover the joins may indicate some pressurization, to help it hold its shape.) No balloon tank can be squashed and squeezed like a child's rubber balloon, or fill a space like a bladder.

As said by many the fuel tanks will be off-the-shelf tanks, and not constructed to fit the diameter of this vehicle. (However neither the O2 or CH4 will have tanks with flat ends!!!) I guess they will fit vertically on the centre line inside the triangular stiffeners, with external pressurisation using likely Nitrogen carried in separate tanks/bottles. This is because the short flight time and very low speed requires less propellant.

I agree the concrete base is a jig. It was used to start the lower section "true", and it is being used that way again with anything else placed there like the thin section reported today. It must be hard working on such flimsy constructions, and the concrete base will make it vastly easier. It will hold a lover ring in shape when an upper one is joined to it.

A separate point. For transport to the launch pad area, it can go in two pieces. However with a low CoG that will not be necessary, just an option.
16 posts since I started this essay... apologies if its now out of date!

meekGee · « **Reply #646 on:** 12/31/2018 05:43 pm »

ok so a few weeks ago I thought the video of the F9 recovering from the spin on the way to an ocean landing was "space vid of the year".

Imma take that back now.

meekGee · « **Reply #647 on:** 12/31/2018 05:47 pm »

Quote from: intelati on 12/31/2018 05:45 pm

Quote from: meekGee on 12/31/2018 05:43 pm
ok so a few weeks ago I thought the video of the F9 recovering from the spin on the way to an ocean landing was "space vid of the year".

Imma take that back now.

Well, of 2018

*pictures*

But you just know there's a video... I mean they can't possibly not have set up a camera overlooking this little operation, right?

billh · « **Reply #648 on:** 12/31/2018 05:52 pm »

This last set of pictures from BocaChicaGal is absolutely amazing! It seems impossible they could already be fitting this thing with a set of engines. Where did they come from? What are they attached to?

To the controversy about the "tin foil hat", I think it is there merely to give the whole thing an aerodynamic shape and to protect whatever is inside the base. I don't think the hopper will fly very high or fast, but I imagine it doesn't have to go too fast before aerodynamic forces will be significant. Hence the need for some kind of streamlining. And is it going to look cool, or what?

gin455res · « **Reply #649 on:** 12/31/2018 05:53 pm »

Quote from: Lars-J on 12/31/2018 05:36 pm

Quote from: bocachicagal on 12/31/2018 05:31 pm
I hope you all wanted more pictures!

Well, they are certainly 3 in one line, just as I predicted.

But are they actual Raptors or placeholder mock-ups to test out initial ground ops? They lack any defining features...
EDIT: Looking closer - their alignment looks a little bit off, so I suspect they are just steel engine nozzles for fit checks. But I have been wrong before!

Yes the centre one looks off. Could it just be a case of the steering (gimballing?) being just a tiny bit off 100.0% true?

OxCartMark · « **Reply #650 on:** 12/31/2018 05:55 pm »

Its December 31st. On December 14th (17 days ago) I was at the far edge in predicting this was this. All of this progress in just 17 days, most of them holidays. This is just freaky nuts vastly fastly progress. [predicting] I think that much of what you are seeing will be the pattern for making production flight versions. Not everything but much of it. Just wait until the crew from the Winnebago factory starts outfitting the interiors [/predicting]

As far as the engines being out of alignment as was commented on earlier that doesn't preclude them from being real and mounted, the direction they're pointed in doesn't make much of a difference during the periods when they aren't producing thrust.

envy887 · « **Reply #651 on:** 12/31/2018 05:57 pm »

Quote from: Lars-J on 12/31/2018 05:36 pm

Quote from: bocachicagal on 12/31/2018 05:31 pm
I hope you all wanted more pictures!

Well, they are certainly 3 in one line, just as I predicted.

But are they actual Raptors or placeholder mock-ups to test out initial ground ops? They lack any defining features...
EDIT: Looking closer - their alignment looks a little bit off, so I suspect they are just steel engine nozzles for fit checks. But I have been wrong before!

Looks like the outer engines are vectored toward the inner one. SpaceX does this on landed Falcon 9 as well, perhaps to give clearance around the engines when they are lowering it onto the stand where they remove the legs.

I would think they are real.

marokrile · « **Reply #652 on:** 12/31/2018 06:06 pm »

Waiting for Santa to take a ride

marokrile · « **Reply #653 on:** 12/31/2018 06:08 pm »

Are this real Raptors, or all is a mockup

matthewkantar · « **Reply #654 on:** 12/31/2018 06:09 pm »

There are two curves on these bells. Has this been shown before?

Cheapchips · « **Reply #655 on:** 12/31/2018 06:10 pm »

Surprised that the engine bells are protruding. Obviously the don't need shielding on the hopper, but I though they'd follow that element of the dearmoon design.

meekGee · « **Reply #656 on:** 12/31/2018 06:11 pm »

Quote from: [email protected] on 12/31/2018 06:08 pm

Are this real Raptors, or all is a mockup

Won't know until either Musk tells us or the water tower fires up.

AndrewSmith · « **Reply #657 on:** 12/31/2018 06:12 pm »

Quote from: matthewkantar on 12/31/2018 06:09 pm

There are two curves on these bells. Has this been shown before?

I noticed this too - nozzle steps are an altitude compensating feature. RVac might be off the table, but a stepped nozzle would allow a single engine type to have 2 discrete operating regimes with only a slight loss in ISP over an optimized bell.

CardBoardBoxProcessor · « **Reply #658 on:** 12/31/2018 06:14 pm »

So the inner nozzle is SL and the outer is kind of Vaccum?

Lars-J · « **Reply #659 on:** 12/31/2018 06:16 pm »

Quote from: AndrewSmith on 12/31/2018 06:12 pm

Quote from: matthewkantar on 12/31/2018 06:09 pm
There are two curves on these bells. Has this been shown before?

I noticed this too - nozzle steps are an altitude compensating feature. RVac might be off the table, but a stepped nozzle would allow a single engine type to have 2 discrete operating regimes with only a slight loss in ISP over an optimized bell.

No, that's not what is going on here. If anything the upper part is just a structural reinforcement of the throat of the engine, or an integrated debris shield. ... Assuming these are real Raptors.