A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Space Science » Policy
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

First Falcon Heavy Launch



 
 
Thread Tools Display Modes
  #1  
Old April 2nd 17, 12:23 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default First Falcon Heavy Launch

The first launch of a Falcon Heavy is currently scheduled for late
this summer. According to Elon Musk, the test flight will be with two
reflown Falcon 9 Cores (plus one new one) and they may attempt to
recover the upper stage to prove full reusability, although he
considers the odds of that succeeding on the first attempt to be low.


--
"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
  #3  
Old April 2nd 17, 02:03 PM posted to sci.space.policy
Vaughn Simon
external usenet poster
 
Posts: 55
Default First Falcon Heavy Launch

On 4/1/2017 11:46 PM, Jeff Findley wrote:
Hopefully nothing will happen to disturb that schedule.


Unfortunately, history predicts otherwise. SpaceX's published schedules
are historically optimistic, sometimes laughingly so.

That said, I'm looking forward to the day that the SpaceX heavy finally
launches, and I have little doubt that it will actually happen.
  #4  
Old April 3rd 17, 12:14 AM posted to sci.space.policy
Brian T.
external usenet poster
 
Posts: 14
Default First Falcon Heavy Launch

On Sun, 2 Apr 2017 14:18:51 -0400, JF Mezei
wrote:

1-If both boosters separate at same time, what sort of logistics are
involved in landing them, presumably at same time?


None. They are GPS-guided. Just tell each booster where it is to go.

two barges a few km apart ? 2 landing pads on ground ? (at what distance?)


SpaceX is preparing satellite (as in secondary) landing pads around
the main pad at LZ-1. So far, SpaceX has not had a problem reaching
the center of LZ-1 or the barges, so landing two stages a few hundred
meters apart probably isn't going to be an issue.

The core stage will land on the barge on operational flights, unclear
what they'll do on the Demo Flight.

Brian
  #5  
Old April 3rd 17, 12:51 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default First Falcon Heavy Launch

JF Mezei wrote:


Questions:


Do you EVER bother to try to find your own answers?


1-If both boosters separate at same time, what sort of logistics are
involved in landing them, presumably at same time?

two barges a few km apart ? 2 landing pads on ground ? (at what distance?)


Trivial to find. One has to wonder why you don't bother.

https://arstechnica.com/science/2017...sters-at-once/

https://www.youtube.com/watch?v=4Ca6x4QbpoM


Apart from extra-terrestrial missions, what sort of commercial payloads
*need* this?

Or is this about launching multiple satellites at the same time?

Or is the goal to use the extra power to deposit second stage at a
higher GTO orbit so it has less work to do?


Again, trivial to find. One wonders why you can't be bothered.

http://www.spacex.com/missions

Generally Falcon Heavy is the alternative for payloads that would
otherwise max out a Falcon 9. It will also allow satellites to carry
much more station keeping fuel, which means they last longer.


But if stage 2 starts at 28° inclination but at higher altitude, doesn't
it make it harder for it to correct inclination to 0° equatorial? Or is
that a minimal concern?


Not a concern at all. Plane change is easier higher up because you're
moving more slowly.


(Or is it expected the 1st stage will make a large contribution to
reduce inclination)


They're going to do what makes sense, just like every other launcher.
Yeah, it's rocket science.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
  #6  
Old April 3rd 17, 03:22 AM posted to sci.space.policy
Jeff Findley[_6_]
external usenet poster
 
Posts: 2,307
Default First Falcon Heavy Launch

In article om,
says...

Questions:


1-If both boosters separate at same time, what sort of logistics are
involved in landing them, presumably at same time?

two barges a few km apart ? 2 landing pads on ground ? (at what distance?)


Nope, two separate landing pads at Cape Canaveral. The boosters
separate fairly early compared to the Falcon 9 first stage, so they'll
have enough leftover fuel to return to the cape safely.

Apart from extra-terrestrial missions, what sort of commercial payloads
*need* this?


All payloads so far where the Falcon 9 first stage was deliberately
expended. This has been due to heavy satellites headed to
geosynchronous orbits.

Or is this about launching multiple satellites at the same time?


Possibly, but this is often difficult to arrange, since both satellites
have to be headed roughly to the same orbit.

Note that Heavy still doesn't have a "high energy" upper stage. It's
essentially got the Falcon 9 upper stage. So even though the LEO
payload of Heavy is quite impressive, the geosynchronous transfer orbit
payload isn't as impressive as you'd think.

The key about Heavy is that they'll recover and reuse both the boosters
and the core (first) stage. So 27 out of 28 engines and 3/4 of the
stages. This will reduce costs, even if the payloads aren't anywhere
near its maximum (mass) capacity. Remember, you have to sacrifice
payload capacity to reserve fuel to return those 3 out of 4 stages.

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.
  #7  
Old April 3rd 17, 04:48 AM posted to sci.space.policy
Fred J. McCall[_3_]
external usenet poster
 
Posts: 10,018
Default First Falcon Heavy Launch

Jeff Findley wrote:


Note that Heavy still doesn't have a "high energy" upper stage. It's
essentially got the Falcon 9 upper stage. So even though the LEO
payload of Heavy is quite impressive, the geosynchronous transfer orbit
payload isn't as impressive as you'd think.

The key about Heavy is that they'll recover and reuse both the boosters
and the core (first) stage. So 27 out of 28 engines and 3/4 of the
stages. This will reduce costs, even if the payloads aren't anywhere
near its maximum (mass) capacity. Remember, you have to sacrifice
payload capacity to reserve fuel to return those 3 out of 4 stages.


Price for a 'new build' Heavy launch is currently about half again as
much as a Falcon 9 (something like $90 million vs $63 million). Price
per pound for a 'new build' Heavy launch is under $1,000/lb at heavy
loads vs around $1350/lb or so for Falcon 9.

Once you start reusing stages prices drop pretty sharply. Falcon 9
goes under $1,000/lb and Falcon Heavy drops to $500/lb or less.
Looking at the latest capabilities chart, Heavy will take about 2.4x
as much payload to LEO as a Falcon 9 can, but can get almost 2.7x as
much to GTO, so it's not horrible. Both start giving up capability if
used as 'non-expendables'.


--
"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
  #8  
Old April 3rd 17, 04:12 PM posted to sci.space.policy
William Mook[_2_]
external usenet poster
 
Posts: 3,840
Default First Falcon Heavy Launch

On Monday, April 3, 2017 at 6:18:53 AM UTC+12, JF Mezei wrote:
Questions:


1-If both boosters separate at same time, what sort of logistics are
involved in landing them, presumably at same time?

two barges a few km apart ? 2 landing pads on ground ? (at what distance?)


Apart from extra-terrestrial missions, what sort of commercial payloads
*need* this?


(1) Launching satellite constellations -
to capture the world's telecom market with direct broadcast two way satellites.
$1.7 trillion per year market (100x NASA budget)

http://www.patentlyapple.com/patentl...ps-beyond.html

(2) Launching solar power satellites -
to capture the world's energy market with energy beaming from space..
$3.5 trillion per year market (200x NASA budget)

https://dspace.mit.edu/openaccess-di...e/1721.1/57581

Capturing even a fraction of these revenue streams provides more than adequate funding for Musk to achieve his goal of making humanity a multi-planet species.



Or is this about launching multiple satellites at the same time?


53 tons is about a dozen powerful communications satellites

or

530 MW solar power satellite at 10 MW per metric ton.


Or is the goal to use the extra power to deposit second stage at a
higher GTO orbit so it has less work to do?


The weight tradeoff for more energetic orbits depends on the specific impulse of your kick stage.

The Falcon Heavy uses propellants that are generally more energetic than solid kick stages

Advanced communications satellites, and presumably newer solar power satellites will use solar
powered ion engines to maximise payloads to higher orbit.

https://www.extremetech.com/extreme/...ines-is-online



But if stage 2 starts at 28° inclination but at higher altitude, doesn't
it make it harder for it to correct inclination to 0° equatorial? Or is
that a minimal concern?


Depends on details. Generally speaking a lower orbit involves a higher delta vee for a given plane change. That's why you boost to a higher orbit, and then do the plane change, if required.

If you are at a 28degree latitude, your minimum inclination at launch is 28 degrees. However, you can launch into a higher inclination orbit. So, if you want to do a sun synchronous polar orbit , you don't need to do any plane change.

(Or is it expected the 1st stage will make a large contribution to
reduce inclination)


Its a trade off of propellant weight versus payload weight. If you add hardware like a separate kick stage, you have to include structure weight. There are other factors as well, but this is the primary one.

The Falcon Heavy Payload User's Guide isn't easily available on line. However, the Falcon 9 Payload User's Guide is! This gives you a detailed look at how you can configure your rocket to achieve the mission you have for it - and the trade offs you will make

http://www.spacex.com/sites/spacex/f...de_rev_2.0.pdf


* * *

SpaceX could continue the excitement, especially if Musk arranges to capture a even a small portion of the energy and telecom markets.

Reinvesting a portion of the funds earned by delivering energy and data to Earth, into advanced propulsion will build bigger hotter rockets going forward. The same satellite hardware that delivers data and power on earth, could be redesigned to service Mars, or the Moon, and the asteroid belt, and beyond.

Power satellites also do double duty powering deep space propulsion systems, without the need of a large solar collector or nuclear power source on the deep space system itself. This is a vast improvement over the chemical kick stage.

For example, a 500 megawatt solar power satellite that uses microwaves, could beam energy to an energetic deep space stage that produces 1.9 metric tons of thrust whilst sustaining a 54 km/sec exhaust speed. At 1/30th gee a 53 ton payload is boosted to Mars in 2.2 hours.

Such a deep space stage is quite capable, and delivers a very large fraction of the orbital payload to its destination. An automated high energy stage like this would also be highly reusable because of short cycle times of less than a day are possible.

For example, a chemical booster is is just about equal a payload to Mars, kicks that payload into a transfer orbit.

An energetic maser powered ion rocket could be as small as 1/10th the size of the chemical booster. (see calculations below)

The chemical booster is limited in its energy, so to recover it, requires that once the payload is on track for Mars, small changes in the chemical boosters course to come back to Earth precisely two years later. So, that it intercepts Earth slows and lands for reuse. Which is just in time for another minimum energy transfer to Mars, which has a 2.15 year synodic period.

But that means the chemical booster spends 2 years in space, and can be used only a handful of times over its life, amortising its cost over fewer flights makes it more costly.

The maser/ion stage considered here powered by a commercial solar power satellite, as an alternative to the chemical booster, is small enough and energetic enough, so that it could slow down after boosting the Mars payload, and return to start position in a matter of hours. Allowing hundreds of times more flights, amortising over more flights, lowers costs by that factor. Reducing the number of launches to support the kick stage, also reduces costs by the same factor.

Calculations

Lox/Methane Booster - with 50% propellant fraction;

Vf = Ve * LN(1/(1-u)) = 3.8 * LN( 1/(1-0.5)) = 2.63 km/sec delta vee

Maser/Ion Booster - with same delta vee

u = 1 - 1 / EXP( 2.63 / 54.00 ) = 0.0476

about 5% - or 1/10th the weight of the chemical booster. That is 53 tons of propellant in the chemical booster is replaced by 5.3 tons of propellant in the ion booster.

Now, if the structure plus recovery propellant of the maser powered ion stage is the same as the chemical stage, say 4.7 tons - to adjust the speed of the empty chemical booster by 0.8 km/sec to place it on a recovery path - requires 0.9 tons of propellant for the chemical stage- leaving 3.8 tons for structure for the chemical booster.

And, to adjust the empty ion booster by 5.3 km/sec - which basically stops the stage and reverses its direction after releasing the 53 ton payload toward Mars- requires only 9.3% or 0.44 tons for a 4.7 ton stage weight - due to its higher exhaust speed - leaving 4.26 tons for structure.

So, launching a 53 ton propellant tank for the ion booster from which a ion kick stage refuels many times, and kick 10 Mars bound payloads to the red planet, with each fuelling flight, whereas the chemical booster kicks only 1 payload every fuel launch.

The hardware is used far more many times and
can put larger payloads into a variety of orbits.

A power satellite network and a communications satellite network around Mars based on the hardware developed for Earth, extends the demand for power and data off world.

It can also be used to power energetic stages to capture and slow incoming payloads, and return those payloads efficiently to Earth, or even send them further into space,

Of course, if powerful gigawatt scale laser beams or maser beams are used to energise rocket on Earth, or on the Surface of Mars, or Venus, reusable single stage stages quite different from the type we are used to that use chemical propellants, become possible.

This not only continues the decline in space launch costs, but also expands the use of space launch going forward. Ballistic transport from point to point on Earth will displace air travel and all other forms of travel going forward, and make access to space seamless, while increasing the demand for energy as the wealth of the world increases as well.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Could Delta IV Heavy use the same technique as Falcon Heavy Alan Erskine[_3_] Space Shuttle 1 May 20th 11 07:56 AM
Falcon Heavy David Spain Policy 8 April 12th 11 08:49 PM
Falcon Heavy Snidely Space Shuttle 2 April 12th 11 08:49 PM
Falcon 9 Heavy vs. Soviet N-1 Pat Flannery Policy 0 November 9th 09 09:52 PM
SpaceX Announces the Falcon 9 Fully Reusable Heavy Lift Launch Vehicle [email protected] News 0 September 12th 05 05:21 PM


All times are GMT +1. The time now is 09:54 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.