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GSLV III Successful Launch



 
 
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  #11  
Old June 7th 17, 01:33 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 1,618
Default GSLV III Successful Launch

In article ,
says...
I think there is still quite some difference between landing a passenger
aircraft, loading new passengers and fuel and taking off again for the
next flight, and re-using a Falcon launcher.


Yes, for Block 4 Falcon 9 first stages I would agree. But, the intent
of the Block 5 first stage improvements is to land them, inspect them,
and refly them up to 10 times before having to do any "tear downs" or
major refurbishment. That's pretty close to "gas and go". Musk has
even publicly stated he'd like to see a rapid first stage reflight (as
in a day) of a Falcon 9 first stage. He is setting the bar so high that
there will soon be much less difference between a liquid fueled first
stage reuse and reflying a passenger aircraft.

I think that no one can dispute the fact that SpaceX is making rapid
progress on first stage reuse. This progress is far more rapid than the
global competition who is either not trying to reuse anything, or have
so far only flown suborbital reuse flights (i.e. Blue Origin).

We're at the cusp of a launch vehicle revolution, yet it appears that
the nay-sayers still aren't convinced.

Jeff
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  #12  
Old June 7th 17, 04:53 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 9,679
Default GSLV III Successful Launch

Rob wrote:

Jeff Findley wrote:
In article ,
says...
Same. India is in the same boat as every other launch company when it
comes to reuse. But, labor costs are far lower in India than in most
other countries launching payloads into orbit, so I'm betting they'll be
able to get away with being all expendable longer than say the US or
Europe (Russia is hard to tell).

It is always hard to tell. The cost per launcher of course goes down
when you make more of them, re-using launchers reduces the number being
produced and increases the cost per launcher. Re-usable launchers could
be more expensive to begin with. There are also costs for refurbishing
the recovered launchers (it is not like they are simply hoisted back on
the pad and re-filled) and there may be an increased risk of failure.
Making the launcher recoverable also reduces its performance.

Only the very naive will think "this launcher costs 50 million so when
we use it twice we go down to 25 million per launch and using it 10 times
our launch costs go down to 5 million".


SpaceX has already reflown one first stage and it reportedly cost them
less than half the cost of new (refurbishment cost versus the cost to
manufacture a new one). But yes, much of what they do is the same
regardless of whether the stage is new or used (like test firing it), so
you don't ever get to recoup those costs by flying a reused stage.


There can be a reduction in cost, but it is not obvious. Apparently
they now have saved some money (2 launches for 1.5 times the cost).


Well, actually it is pretty obvious, which is why almost everyone but
NASA is headed in that direction.

Still, they're saving money and they still have not "worked all the bugs
out of the process". This year, they'll start flying Block 5 first
stages which incorporate changes to make reuse easier and cheaper.
They're learning and improving.


When a refurbished launcher fails, and it turns out to be due to the
re-use, they need quite some launches to recover that cost.


That's what insurance is for, if you think you need it.

Plus, you are ignoring the very real "infant mortality" problem. On an
expendable, there is always the possibility that some manufacturing
defect will creep into the vehicle causing it to fail. Since it's
expendable, its first and only flight is both test flight and
operational flight.


Of course. But there is also the problem of failures due to using a
refurbished launcher that may have damage or wear.


This same risk exists for your car or an airliner and is about the
same order of magnitude. It's probably lower for the reused rocket,
since it gets a much more thorough going over than your car or the
airplane.

From the very beginning Falcon stages have been test fired before flight
(in Texas) to prove them out. So even on an "expendable" Falcon 9 first
stage, its first flight is not the first time it's been fired.


This is not specific for SpaceX, component and system tests are done
by other companies as well.


Actually that kind of is specific for SpaceX. I'm not aware of any
other company that test fires flight engines before flying them or
does a full-up stacked fuel of the vehicle before the main event.

Also, note that even new copies of an existing passenger jet design are
test flown at least once before putting paying passengers on board.
Only the very naive would put paying passengers on the very first flight
of a newly built aircraft. Yet some people don't even blink when a very
expensive payload is put on top of a never before flown copy of a launch
vehicle.


I think there is still quite some difference between landing a passenger
aircraft, loading new passengers and fuel and taking off again for the
next flight, and re-using a Falcon launcher.


Why do you think this?

In the early days of Space Shuttle there was also the myth (probably
mainly among the public and press) that this space vehicle would operate
like a plane: land, re-fuel and take-off. In practice it was (or turned
out to be) quite different from that.


In the early days of Space Shuttle it was a very different vehicle.
They compromised that design when they took USAF money. As I said
earlier, it is certainly possible to do reuse badly, but you have to
work at it. NASA deliberately made a 'reusable' vehicle that was
hideously expensive to fly. The thing of note with regard to the rest
of your case against reusables is that they never lost a vehicle due
to wear and tear from it having flown before.


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




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