BFR early next year.

In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.

That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.

For use as a possible military transport, it might be considered safe
enough. But even then, you can only land and take off at facilities
that have at least a concrete pad and LOX/liquid methane in quantity.
So even for the military, it would require quite a big of infrastructure
investment for something that's not really useful on a day to day basis.
So I doubt even the US military would be very interested in it as a
troop transport.

Now for rapid launch response, I could see DOD being very interested. A
fully reusable TSTO means you would have a huge surge capacity to launch
a lot of stuff into orbit in a short amount of time. Space marines,
here we come.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Jeff Findley wrote on Fri, 16 Mar 2018
10:30:05 -0400:

In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.


That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.


But that's sort of the point of the thing, whether you're talking P2P
on Earth or Earth to elsewhere. Until proven otherwise, I'm inclined
to take Musk at his word with regard to 'airliner reliability' for the
thing.


For use as a possible military transport, it might be considered safe
enough.


Say what? If it's not safe for civilian passengers it's not safe for
military passengers.


--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney

In article ,
says...

Jeff Findley wrote on Fri, 16 Mar 2018
10:30:05 -0400:

In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.


That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.


But that's sort of the point of the thing, whether you're talking P2P
on Earth or Earth to elsewhere. Until proven otherwise, I'm inclined
to take Musk at his word with regard to 'airliner reliability' for the
thing.

I'm hopeful, but simultaneously cautious. No one has attempted a
reusable orbital spacecraft quite like BFS. Being a first anything is
bound to create issues to chase.

We're up to Block 5 for Falcon 9, but even it hasn't flown yet. I
believe it should be flying quite soon though. This will hopefully be
the last block for Falcon 9. Falcon 9 first flight was June 2010, so
it's taken 8 years to mature the design from first flight. No doubt
BFR/BFS will take many years to mature its design as well.

For use as a possible military transport, it might be considered safe
enough.


Say what? If it's not safe for civilian passengers it's not safe for
military passengers.

Really? The V-22 Osprey (new tech in the 1990s) has crashed with some
regularity ever since it entered service:

https://en.wikipedia.org/wiki/Accide...lving_the_V-22
_Osprey

A disturbing number of these crashes were during training missions, so
it's not like they were in active combat. And the last time I checked,
we still fly the V-22 Osprey because of its unique capabilities.

I assert that BFR/BFS would be little different than the V-22 in terms
of both unique capabilities and could be little different when it comes
to its reliability as an air/space transport craft.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On 3/16/2018 10:30 AM, Jeff Findley wrote:
In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.

That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.


We disagree on this point. Because 1st gen will have to do for a lot of
the "heavy lifting" when it comes to crew. There is a lot of engineering
going into BFS, but "generations" if needed will come quickly, ala Block
1..n. Some of Elon's plan as revealed last year hints that this is
viewed as a means of revenue generation to at least earn back some of
the NRE since government isn't financing this "directly". Plus with no
other enhancements planned for F9 or F9H or beyond the current
non-propulsive landing Dragon V2, this is the all eggs in one basket for
SpaceX's future. I suspect P2P will start maybe with one or more drone
ship landings at sea, followed quickly with a short hop land-based P2P,
likely my guess from Boca Chica to Cape Canaveral LZs, pending FAA
approval. The path from this to passenger service seems far more direct
to me than building a Mars (or Moon) colony. At least in the short term.
But admittedly, that's just me.

Another question is whether the current drone ship is capable of BFS
landings? I understand there is some new activity at Marchand. So I
suspect the answer is no. But I could be wrong. There is some rumbling
about using anchored platforms in the Gulf of Mexico. Stay tuned.

As a final note, in reviewing the comments made by Elon at least year's
conference, he made an almost aside comment that BFS was sort of like a
mashup of a 2nd stage and Dragon. I suspect that possibly one of the
reasons Elon may not be far off on his estimates for 1st flights of BFS
is because there is a good deal of truth behind that statement. Which
might also mean that at least Block 1 BFS has less capability than the
Mars version Elon talks about. If the OD (outer diameter) of the
fuselage stays constant that might mean the interior of Block 1 BFS is
much much less capable. Perhaps almost 1-for-1 on par with current
Dragon V2. But enhancement would not require modifications to the
exterior or stage couplings. Only the dry mass increases, which ought to
be able to be handled by propellant loading. There's a whole lot (more)
to come here....

Dave

In article , says...

On 3/16/2018 10:30 AM, Jeff Findley wrote:
In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.

That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.


We disagree on this point. Because 1st gen will have to do for a lot of
the "heavy lifting" when it comes to crew. There is a lot of engineering
going into BFS, but "generations" if needed will come quickly, ala Block
1..n. Some of Elon's plan as revealed last year hints that this is
viewed as a means of revenue generation to at least earn back some of
the NRE since government isn't financing this "directly". Plus with no
other enhancements planned for F9 or F9H or beyond the current
non-propulsive landing Dragon V2, this is the all eggs in one basket for
SpaceX's future. I suspect P2P will start maybe with one or more drone
ship landings at sea, followed quickly with a short hop land-based P2P,
likely my guess from Boca Chica to Cape Canaveral LZs, pending FAA
approval. The path from this to passenger service seems far more direct
to me than building a Mars (or Moon) colony. At least in the short term.
But admittedly, that's just me.

The SpaceX communications satellite network will play a big role in
filling BFS flights. Considering how many satellites they're proposing
(what is it now, 1k+ or 2k+?) and that they'll last 5 years, SpaceX
could be launching their own satellites pretty much "forever".

Another question is whether the current drone ship is capable of BFS
landings? I understand there is some new activity at Marchand. So I
suspect the answer is no. But I could be wrong. There is some rumbling
about using anchored platforms in the Gulf of Mexico. Stay tuned.

I'm going to say no. The barges aren't that big and they're subject to
rough seas. A recent Falcon 9 flight had to cancel the barge landing
due to bad weather. You won't want to do that with BFR. You'll almost
certainly want a bigger more stable platform if off shore landings are
required.

As a final note, in reviewing the comments made by Elon at least
year's
conference, he made an almost aside comment that BFS was sort of like a
mashup of a 2nd stage and Dragon. I suspect that possibly one of the
reasons Elon may not be far off on his estimates for 1st flights of BFS
is because there is a good deal of truth behind that statement. Which
might also mean that at least Block 1 BFS has less capability than the
Mars version Elon talks about.

Block 1 will almost certainly not be Mars landing capable.

If the OD (outer diameter) of the
fuselage stays constant that might mean the interior of Block 1 BFS is
much much less capable. Perhaps almost 1-for-1 on par with current
Dragon V2. But enhancement would not require modifications to the
exterior or stage couplings. Only the dry mass increases, which ought to
be able to be handled by propellant loading. There's a whole lot (more)
to come here....

This bit I have no idea what you're talking about. ASCII doesn't put an
accurate picture in my head.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Jeff Findley wrote on Fri, 16 Mar 2018
12:44:48 -0400:

In article ,
says...

Jeff Findley wrote on Fri, 16 Mar 2018
10:30:05 -0400:

In article , says...

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.


That's the one part of BFR/BFS I don't take seriously. As a first
generation VTVL TSTO it's not likely to be safe enough for routine
passenger transport. Maybe the second or third generation will be.


But that's sort of the point of the thing, whether you're talking P2P
on Earth or Earth to elsewhere. Until proven otherwise, I'm inclined
to take Musk at his word with regard to 'airliner reliability' for the
thing.


I'm hopeful, but simultaneously cautious. No one has attempted a
reusable orbital spacecraft quite like BFS. Being a first anything is
bound to create issues to chase.

We're up to Block 5 for Falcon 9, but even it hasn't flown yet. I
believe it should be flying quite soon though. This will hopefully be
the last block for Falcon 9. Falcon 9 first flight was June 2010, so
it's taken 8 years to mature the design from first flight. No doubt
BFR/BFS will take many years to mature its design as well.


Yes, I expect we'll see some 'block improvements' along the way, but I
would bet they have more to do with the 'reusability' than any
reliability or safety issues in flight.

For use as a possible military transport, it might be considered safe
enough.


Say what? If it's not safe for civilian passengers it's not safe for
military passengers.


Really?


Yes, really. The idea that "they're only military guys so we don't
care so much about killing them in accidents" is both insulting and a
preposterous notion.


The V-22 Osprey (new tech in the 1990s) has crashed with some
regularity ever since it entered service:

https://en.wikipedia.org/wiki/Accide...lving_the_V-22
_Osprey


I see 12 crashes and 8 'incidents' over a span of a quarter century.
Did you look at the figures for helicopters or commercial aircraft?
They seem to crash fairly regularly, too, and commercial aircraft
aren't doing anything complex or difficult.


A disturbing number of these crashes were during training missions, so
it's not like they were in active combat. And the last time I checked,
we still fly the V-22 Osprey because of its unique capabilities.


Why would that be 'disturbing'? Most military aircraft crashes are
during training. It's the nature of the beast. We 'still fly the
V-22' because there is nothing wrong with the aircraft and the
accident rate isn't particularly high given what they do with it.


I assert that BFR/BFS would be little different than the V-22 in terms
of both unique capabilities and could be little different when it comes
to its reliability as an air/space transport craft.


I hope it isn't. What that means is that there will be some teething
pains early and a couple design defects to correct and then it will be
a perfectly fine vehicle.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw

JF Mezei wrote on Fri, 16 Mar 2018
17:05:50 -0400:

On 2018-03-16 03:16, Niklas Holsti wrote:

I hope that SLS is also a transitional temporary project, and that BFR
will replace it. In this ephemeral role, too, Falcon Heavy competes with
SLS.


Since SLS has no commercial goals, has limited set of test flights with
no planned use beyond one crewed flight around the moon, it is not in
any competition except for sucking up government funding away from from
more productive uses.


I'm sure we've covered this before. While of course stuff out more
than half a dozen years tends to get tentative, there are certainly
'planned uses' for SLS beyond one flight around the Moon. That flight
is EM-2 (EM-1 is the same mission but unmanned) currently scheduled
for 2022. I see 9 more missions planned after that, mostly involved
with putting together the Lunar Orbital Platform - Gateway. Is any of
this sounding at all familiar to you or have you once again lost all
memory of anything that was told to you before lunch?


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

JF Mezei wrote on Fri, 16 Mar 2018
17:31:33 -0400:

On 2018-03-16 16:15, Jeff Findley wrote:

Block 1 will almost certainly not be Mars landing capable.

If it is able to propulsively land on Earth, doesn't that more or less
imply ability to land on Mars?


Not necessarily. You get a lot of help from aerobraking on Earth.
Mars is much more difficult because the air is so thin.


How much bigger would the paddles have to be to have same aerodynamic
control in Mars atmosphere vs Earth?


Atmospheric pressure on Mars is about 0.6% that of Earth.


In making the initial design, don't they have to make sure the
architectire will allow a Mars landing? For instance, calculate how
many engines will be needed to land and take off from Mars with X
payload, verify that there is enough space for whatever aerodynamic
devices will be needed (or failing that, allow for enough side thrusters
to provide attitude control during re-entry/landing etc ?


You'd certainly like it to, but go back to the example of Space
Shuttle Enterprise. It was built for drop testing. As such, they
didn't need to shave weight as aggressively, etc. It was originally
intended to rebuild it to 'space standard' after the tests were over,
but that just proved to be much more expensive than they'd
anticipated. The same thing could wind up being true of the first
Block of BFR Spaceship.

I'd be more inclined to think of it as 'Block 0', since I doubt if it
will consist of more than a couple ships, at most.


In other words, doesn't the 1.0 design have to inherently be
conceptually able to land on Mars, with subsequent iterations just
improving on the situation? (I use "conceptually able to land" because
I realise the 1.0 version may not have the software to do it, and
aerodynamic controls designed for Earth atmosphere).


Don't blame the software. The DESIGN might be fine, but they might
not build totally to that design. Again, think about Space Shuttle
Enterprise.


If your 1.0 design is say 25% short on thrust needed to land on Mars,
can you really bank on being able to improve engine performance by 25%
within say 15 years?


I'd say they probably can. They lowered the chamber pressure of
Raptor to make them easier to build and safer to run/reuse. SpaceX
plans to increase chamber pressure by 20% on future Raptor blocks.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw

JF Mezei wrote on Sat, 17 Mar 2018
02:40:04 -0400:

On 2018-03-16 21:57, Fred J. McCall wrote:

Not necessarily. You get a lot of help from aerobraking on Earth.
Mars is much more difficult because the air is so thin.


Which would mean BFS needs to have more oumph! from its engines, right?
So when they make the general design, upon which, the first test flight
will be based, they need to factor in enough Raptor engines for it, right?


Yes, they have to actually design things, which seems to be what
you're wailing about.


Enterprise didn't have engines and didn't even have fake engine bells,
it had a aerodynamic cowl in the bacjk, but the dimensions of the engine
area were the "right" ones for the 3 SSMEs and 2 OMS engines. And this
was "sized" right from the size for the types of missions the Shuttle
would be able to fly.


So?



Shuttle Enterprise. It was built for drop testing. As such, they
didn't need to shave weight as aggressively, etc.


Modern design/manufacturing make this different. The prototype tanks
cannot be built by hand. The precise fibre weaving patterns have to be
developped because you will be fueling the first prototype. You can't
just put an oversize plastic coke bottle in its place until the real
tank is designed. And SpaceX has designed the real tank.


What are you gibbering about now?


Similarly, you can't put an aérodynamic cowling below the BFS in lieu of
engines. You have to have the real engines if you want the prototype
rocket to lift off and land.


You don't need the vacuum engines to lift off and land. You do need
some if you're planning on going clear to space, but even then you
probably don't need all of them until you start flying heavy cargos.


So while Enterprise only had to demonstrate its glider capabilities,
the BFS prototype will have to demonstrate a far greater proportion of
its mission profiles. It needs real engines, real tanks, and real
landing legs and software. As a vehicle, it will lack the heat shield.
(or may have it, but won't be tested) and obviously, lack a man rated cabin.


If you don't need the heat shield then you don't need the vacuum
engines. I don't know why you're so wrapped around the axle about the
damned tank, since we all know that's done.


The other difference is that while NASA was able to greatly reduce
weight after Enterprise prototype, this doesn't happen anymore because
the modern design software already optimizes structures and generally,
some parts need to be beefed up after prototype is built. (aka: 787
ended up significantly heavier than originally predicted by Boieing,
same with the A380 from Airbus).


Untrue. It certainly does still happen.


Consider Falcon Heavy which also had to be beefed up once SpaceX
realised it needed much strenghtening.


One core out of three.


What remains to be seen is whether the first flying prptotype will have
some "heavy" skin to simulate the weight of a heat shield. (more to
measure landing/guidance than to measure launch performance).


Heat shields aren't that heavy compared to other structure. And do
you not pay attention or does your memory really reset at midnight
every day. Musk has said that they will probably build the
'Grasshopper' article without either vacuum engines or the heat shield
because that gives them a bigger fuel margin during early testing and
those things can be added later.


In most cases, modern airplanes tend to have first production units
being heavier than first prototype. During flight testing, they notice
the need to strenghten a certain area etc etc. (and then over the years,
they manage to reduce weight bit by bit).

The Shuttle was different because Enterprise was designed as a proof of
concept


No, it was designed as a test article, which is not the same thing.



It was originally
intended to rebuild it to 'space standard' after the tests were over,
but that just proved to be much more expensive than they'd
anticipated. The same thing could wind up being true of the first
Block of BFR Spaceship.


With Modern design techniques, Enterprise would have been built
pre-optimized.


Horse****. They didn't design the thing using bearskins and stone
axes, you know.



Don't blame the software. The DESIGN might be fine, but they might
not build totally to that design. Again, think about Space Shuttle
Enterprise.


Everything from tanks to bottom should have a "dinal" design aspect to
it (one which will be tweaked, but nevertheless, planned to be
functional. Sicne the "spaceship" portion won't be done and BFS 0.1
might as well carry another car inside, the top portion may just be an
aerodynamic shell from the composite design point of view (no load
bearing capability). But the "business end" should be fully designed,
unlike Enterprise whose business end had an aérodynamic cowling instead
of the real stuff.


No vacuum engines and no heat shield. Say it with me....


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

In article ,
says...

On 2018-03-16 16:15, Jeff Findley wrote:

Block 1 will almost certainly not be Mars landing capable.

If it is able to propulsively land on Earth, doesn't that more or less
imply ability to land on Mars?

Block 1 might not be able to be refueled, so it couldn't get to Mars in
the first place. The first block will almost certainly be less capable
than later Blocks. Even SpaceX might not know all its limitations until
it's tested. There is no real substitute for test flights.

I write engineering software for a living. It's "garbage in, garbage
out". If the engineers don't input exactly the right constraints,
loads, material properties, and etc. the best simulation in the world is
still going to give you a wrong result. That's why you test, to verify
that your design actually works the way you intended.

Look at how many tries it took SpaceX to land a Falcon 9 first stage.
Many things had to be tweaked until they got it right.

The first Block of BFR/BFS will not be perfect.

How much bigger would the paddles have to be to have same aerodynamic
control in Mars atmosphere vs Earth?

From pictures and drawings, there are no grid fins on the Big Falcon
Spaceship (2nd stage).

The Big Falcon Rocket (1st stage) has them, but it's entirely
suborbital. It's never going to orbit let alone Mars.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.