Awesome video of the new Falcon reusable rocket launching and landing

In article ,
says...

On 4/22/2014 7:39 AM, Jeff Findley wrote:
Some people are making this whole thing out to be harder than it really
is. Losing a satellite, or putting it into the wrong orbit, because one
out of nine engines fails is absolutely unacceptable. To mitigate this,
Falcon 9's first stage*already* needs to carry extra fuel in order to
handle engine out scenarios.


OK I'm reaching a bit here but just for the sake of discussion...

I realize that you can't anticipate every possible failure, but one risk
that I see with the Space-X many-engine format is the possibility of a
major engine failure taking out adjacent engines.

This is true, which is why there is shielding between engines on Falcon
9.

Could there be a possibility of shuttle-style scenarios to return the
rocket, payload and all, following (say) the loss of two or three
engines rendering orbit impossible?

Possibly, but you'd have to design for that case, which would drive up
the mass of the landing legs, especially if you're talking about trying
to land with both the upper stage and the payload on top. This might
become easier if the 2nd stage can land independent of the first and if
it's designed to land with a payload on top.

But I wouldn't expect this from a "first generation" reusable. It's
going to be hard enough just to recover the empty stages, let alone
trying to recover a payload.

Control under asymmetric thrust conditions might be one obvious
deal-killer, plus the CG of the entire package would be totally
different. The shroud could be sacrificed before landing to reduce
weight. Second stage fuel dumping would also be theoretically possible,
at the price of increased complexity.

Control typically isn't a problem, with the exception of things like
engine failure before clearing the launch tower. The first stage
engines gimbal and they can be throttled.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In sci.space.policy message orfairbairn-963DEE.20412520042014@70-3-168-
216.pools.spcsdns.net, Sun, 20 Apr 2014 20:41:25, Orval Fairbairn
posted:

In article ,
Brad Guth wrote:


A truly reusable fly-by-rocket is a serious game changer.

Wondering how much extra fuel was consumed.

Propellant usage would also be my top question -- followed by heat
damage to the base of the rocket.

1. If you use such a large mass fraction of propellant backing down to
landing, it loses all utility as a launch vehicle. It is nice to see
that Space-X can maintain enough control to back down to a powered
landing, but the utility question remains.

Non-reusable Falcon 9 sees an adequate market for fairly large payloads.
Even if reusable F9R could only lift half of that payload and was only
recovered with 90% success, by effectively reducing the dry cost of the
first stage to 10% of what it was the F9R would dominate the market for
that size of payload - and AIUI they are expecting to do better than
those figures.

2. If the base gets so much heat and flame damage that it warps the
structure, the vehicle is only semi-reusable.

If the base gets so much heat and flame damage that it warps the
structure, then the design can be modified to include more insulation or
less warpable structure.

AIUI, F9R uses three engines before it enters much atmosphere, at which
time the exhaust has nothing to stop it; but only the central engine
after aerodynamic deceleration, at which time the eight inactive bells
will shield much of what is above them

--
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Web http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
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Dr J R Stockton wrote:
AIUI, F9R uses three engines before it enters much atmosphere, at
which time the exhaust has nothing to stop it; but only the central
engine after aerodynamic deceleration, at which time the eight
inactive bells will shield much of what is above them

Would they need/want to be running a little bit of either fuel or
oxidizer through the non-operating bells to keep them sufficiently
cool?

rick jones
--
Process shall set you free from the need for rational thought.
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

In article id,
lid says...

In sci.space.policy message orfairbairn-963DEE.20412520042014@70-3-168-
216.pools.spcsdns.net, Sun, 20 Apr 2014 20:41:25, Orval Fairbairn
posted:

Propellant usage would also be my top question -- followed by heat
damage to the base of the rocket.

1. If you use such a large mass fraction of propellant backing down to
landing, it loses all utility as a launch vehicle. It is nice to see
that Space-X can maintain enough control to back down to a powered
landing, but the utility question remains.

Non-reusable Falcon 9 sees an adequate market for fairly large payloads.
Even if reusable F9R could only lift half of that payload and was only
recovered with 90% success, by effectively reducing the dry cost of the
first stage to 10% of what it was the F9R would dominate the market for
that size of payload - and AIUI they are expecting to do better than
those figures.

True.

Another bit of news fairly recently was the announcement that SpaceX has
secured a 20-Year lease agreement with NASA for use of Launch Complex
39A (i.e. one of the former shuttle/Saturn pads since SLS will fly so
infrequently that it only needs one of the two pads).

http://www.americaspace.com/?p=58044

Falcon Heavy ought to be able to make use of three Falcon 9R first
stages (as two boosters and one first stage core). Recovering these
would mean that SpaceX would be reusing three out of four stages which
means 27 out of 28 main engines. This would be huge since even with the
payload "penalty" of reuse, I've got to believe that it would have quite
significant payload (larger even than a completely expendable Falcon 9).

Still, SpaceX is focusing on the right problem, which is reducing the
total life cycle costs of launching payloads into orbit. This means
they are optimizing for cost, not "performance" as in in the traditional
approach which leads to maximizing payload mass while minimizing the dry
mass of the launch vehicle (i.e. the approach taken in the 50's and 60's
to develop ICBMs designed to nuke the USSR from launch sites in the US).

It's a bit shocking that SpaceX's competition is still approaching the
problem like their predecessors did well over a half a century ago and
poking fun at SpaceX using metrics more applicable to expendable ICBM
design than sane launch vehicle design.

2. If the base gets so much heat and flame damage that it warps the
structure, the vehicle is only semi-reusable.

If the base gets so much heat and flame damage that it warps the
structure, then the design can be modified to include more insulation or
less warpable structure.

I doubt that this is really going to be an issue. First stage Merlin
engines are regeneratively cooled, so the engine(s) running shouldn't be
a problem. The stage will see some heating, but during launch, exhaust
gas recirculation is a real problem which already requires thermal
protection of the base of the first stage. Even if it's required,
"upping" the thermal protection a bit for the base of the first stage
doesn't seem like a big deal.

AIUI, F9R uses three engines before it enters much atmosphere, at which
time the exhaust has nothing to stop it; but only the central engine
after aerodynamic deceleration, at which time the eight inactive bells
will shield much of what is above them

Of course, that first recovery burn is done at supersonic speeds with
the stage pointed such that the engines are traveling into the velocity
vector (i.e. it's flying *backwards*). So, some people have been a bit
nervous about this (it's similar to the burn the shuttle would have done
for a RTLS). But, on this last flight, it seems like the Falcon 9R
first stage made it all the way to sea level and "landed" successfully.
This demonstration should help inspire confidence in SpaceX's approach
to first stage reusability.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article ,
says...

Dr J R Stockton wrote:
AIUI, F9R uses three engines before it enters much atmosphere, at
which time the exhaust has nothing to stop it; but only the central
engine after aerodynamic deceleration, at which time the eight
inactive bells will shield much of what is above them

Would they need/want to be running a little bit of either fuel or
oxidizer through the non-operating bells to keep them sufficiently
cool?

That's one approach to keeping them cool if radiative cooling of the
non-operating engines isn't enough. I'm not sure LOX would be a good
idea since LOX in the presence of intense heat and *any* fuel source
(even some metals) is going to lead to a "bad day".

But, such things can be done with careful engineering. Modern Russian
regenerative LOX/kerosene engines seem to be able to run the turbine(s)
in their engines oxygen rich without them melting down, which is a feat
once thought impossible by western aerospace engineers.

Why Russian rocket engines are so popular today
http://tinyurl.com/mfw422l

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

To reduce landing weight in a off nominal launch, they could use a escape tower for both human and unmanned but high value payloads, since the escape system and fault detection will already be designed

many payloads cost millions just might be worth it

On Monday, April 21, 2014 4:43:34 PM UTC-7, Greg (Strider) Moore wrote:
"Brad Guth" wrote in message

...



On Sunday, April 20, 2014 5:41:25 PM UTC-7, Orval Fairbairn wrote:

In article ,



Brad Guth wrote:







On Saturday, April 19, 2014 8:34:35 PM UTC-7,

wrote:



"Behold the first test of the Falcon 9 Reusable rocket, launching and

then







smoothly landing in another location--an entire rocket going up and

landing



back







on Earth ready to be refilled and launched again. Unlike the

Grasshopper,



this



thing is huge!"











See:







http://sploid.gizmodo.com/awesome-vi...able-rocket-la



unchi-1564763284/+jesusdiaz







That's a terrific demonstration, as proof of accomplishing what other

space



agencies (including our NASA) still can not do.







A truly reusable fly-by-rocket is a serious game changer.







Wondering how much extra fuel was consumed.







Propellant usage would also be my top question -- followed by heat

damage to the base of the rocket.





1. If you use such a large mass fraction of propellant backing down to

landing, it loses all utility as a launch vehicle. It is nice to see

that Space-X can maintain enough control to back down to a powered

landing, but the utility question remains.





2. If the base gets so much heat and flame damage that it warps the

structure, the vehicle is only semi-reusable.



Perhaps a brief refueling in LEO before attempting its fly-by-rocket

landing. Of course we'd have to place a sufficient spare amount of HTP

plus a little something else of a hydrocarbon on orbit first.





You just made the problem much harder.



The fuel you need to get the 1st stage into orbit is what you would use for

landing.



And if you get it into orbit, it has a LOT more energy you have to lose

before landing.



--

Greg D. Moore http://greenmountainsoftware.wordpress.com/

CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net

Being that the landing mass is greatly reduced (inert mass being the same), I'd think it would only demand a little over half as much fuel (possibly 2/3) for the soft landing phase.

In article ,
says...

To reduce landing weight in a off nominal launch, they could
use a escape tower for both human and unmanned but high value
payloads, since the escape system and fault detection will
already be designed

"They" could, but such systems are quite heavy and introduce their own
failure modes (e.g. see example of the escape tower originally designed
for or Orion on top of Ares I). On top of that, after the "escape"
burn, such systems are typically equipped with parachutes and have no
ability to "fly-back" to the launch site. For KSC or Cape Canaveral AFB
launches, this means dunking your expensive payload in salt water, which
is *not* advisable for typical aerospace payloads.

Ditching the solids and parachutes in favor of liquids would mean
duplicating the systems already on the reusable stages, which seems
quite silly.

In other words, this is a very bad idea any way you look at it.

many payloads cost millions just might be worth it

No, it wouldn't. Expendable, single purpose escape systems originally
designed to get manned capsules off ICBMs have little to no utility when
paired with sanely designed reusable launch vehicles.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In article ,
says...
Perhaps a brief refueling in LEO before attempting its fly-by-rocket
landing. Of course we'd have to place a sufficient spare amount of
HTP plus a little something else of a hydrocarbon on orbit first.

You just made the problem much harder.
The fuel you need to get the 1st stage into orbit is what you would
use for landing.

And if you get it into orbit, it has a LOT more energy you have to
lose before landing.

Being that the landing mass is greatly reduced (inert mass being the
same), I'd think it would only demand a little over half as much fuel
(possibly 2/3) for the soft landing phase.

You've got to actually do the math, but given the velocity of the
vehicle at staging (and the *squared velocity* term in the kinetic
energy equation), it's quite clear that far less delta-V is needed to
land than would be needed to get to orbit, especially when one considers
that much of the braking needed for landing can come from atmospheric
drag.

If your goal is to get the separated stage to orbit, you've got both
atmospheric drag and gravity losses fighting you all the way to orbit.
That would literally be an uphill battle.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

In sci.space.policy message
-september.org, Wed, 23 Apr 2014 07:41:10, Jeff Findley jeff.findley@s
iemens.nospam.com posted:

In article id,
says...

AIUI, F9R uses three engines before it enters much atmosphere, at which
time the exhaust has nothing to stop it; but only the central engine
after aerodynamic deceleration, at which time the eight inactive bells
will shield much of what is above them

Of course, that first recovery burn is done at supersonic speeds with
the stage pointed such that the engines are traveling into the velocity
vector (i.e. it's flying *backwards*). So, some people have been a bit
nervous about this (it's similar to the burn the shuttle would have done
for a RTLS). But, on this last flight, it seems like the Falcon 9R
first stage made it all the way to sea level and "landed" successfully.
This demonstration should help inspire confidence in SpaceX's approach
to first stage reusability.

I believe that the first, three-engine, recovery burn is done in near-
vacuum, so the heating effects will be about one-third overall of what
they were at Stage 1 MECO 1, just before the release of Stage 2.

The shuttle RTLS burn is different; it would have been done with an
initially less empty Tank (if there had been a sufficient failure near
STS MECO, they would have gone on, to land in Europe).

It appears that it took 8 seconds from reaching the water to loss of
signal, which is a reasonable duration, AFAICS, for the falling over of
a Falcon which would have made a good landing had there been land
instead of sea at the touchdown point - and therefore the matter of
getting down in one piece to zero altitude at zero speed while pointing
upwards is substantially solved but perhaps not perfected.

Next time legs are deployed, I suggest that they might try to land on a
tangible floating target, one with a middle to aim for, but not
necessarily one from which a Falcon could be recovered in a moderately
dry condition. Or on an aircraft carrier, but one with a WWII UK-style
deck.

--
(c) John Stockton, nr London, UK. For Mail, see Home Page. Turnpike, WinXP.
Web http://www.merlyn.demon.co.uk/ - FAQ-type topics, acronyms, and links.
Command-prompt MiniTrue is useful for viewing/searching/altering files. Free,
DOS/Win/UNIX now 2.0.6; see my http://www.merlyn.demon.co.uk/pc-links.htm.