Author Topic: General Falcon and Dragon discussion (Thread 14)  (Read 156646 times)

Offline gongora

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #360 on: 05/07/2017 02:28 AM »
I don't recall seeing this posted yet, although I may have missed it when I was on vacation.  It's a pretty good interview with Gwynne.

[Via Satellite] Shotwell: Ambitious Targets Achievable This Year

Quote
...
What Shotwell envisions as a great year for SpaceX would mean launching every customer that wants to launch and is ready to launch this year. But, even Shotwell can’t fully predict how many launches that goal would entail. “Who knows how many launches that is? That could be up to two Falcon Heavy flights and maybe 24 Falcon 9 flights, but there is a bunch of movement in the manifest at the end of the year so I don’t know how many people need to fly this year or how many are ready. But we want to be prepared for everybody that wants to fly this year,” she says.
...
In terms of when we might see significant price declines, Shotwell admits “it will take a few years” for the contracts to come in. However, SpaceX has invested a lot of money in this particular area. “We want to make sure we are fair about that cost. Frankly, the final spin on Falcon 9 will be rolling out a little bit later than mid-year, and that is really the stage that rolls in all the lessons learned on reusability that we have learnt to date. Those vehicles will be highly reusable — 10 times at least. When those vehicles are flying regularly, we will start seeing more pressure around the launch price side,” she adds.
...
In terms of trends, Shotwell sees a trend of a bifurcation in the market. She says there are a couple of satellite providers making their satellites bigger. “Some of that is basically putting a giant satellite on Falcon 9 with a lot of propellant, which would normally be a very heavy satellite, even potentially hard for Falcon 9 to throw. But when you put so much propellant on that satellite, they can get themselves to orbit even from a sub-synch. A couple of manufacturers are doing that … [sending] an over 7-ton satellite on Falcon 9 to GTO.
...

Online Ben the Space Brit

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #361 on: 05/10/2017 10:05 AM »
So, we know that SpX-CRS-11 has a reused Dragon spacecraft. Is there any talk of a reused Dragon flying on a reused first stage any time soon? CRS-12 is a bit too soon but, by 2H 2017, at least two or three cores will have re-flown and NASA could be at least given some measure of assurance that they do fly instead of just blow up.
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Online Rebel44

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #362 on: 05/11/2017 11:59 AM »
Any opinions, when will SpaceX eliminate Static firing in McGregor and/or on a launch pad?

Offline rockets4life97

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #363 on: 05/11/2017 12:09 PM »
Any opinions, when will SpaceX eliminate Static firing in McGregor and/or on a launch pad?

It looks like going to McGregor has been eliminated for the re-use of b1029.2 for the upcoming BulgariaSat launch. So, it looks like re-use will eliminate stops back at McGregor.

As for new boosters, no idea. No sooner than block v and even then I expect them to keep testing them at McGregor.


Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #364 on: 05/11/2017 02:16 PM »
Any opinions, when will SpaceX eliminate Static firing in McGregor and/or on a launch pad?
I think they'll keep all test firings in McGregor for new boosters. The goal is to fly them at least 10x moving forward, and eventually the "flight proven" mantra is likely to be proven with stats, that creates the interesting conundrum that if new boosters are slightly less safe than reused ones, they must be tested plenty.
Once a booster has been recovered, it has been to hell and back, as long as it shows no sign of damage, it only gets the pre launch static fire.

Which creates an interesting challenge, once upper stages are recovered, they probably should be test fired before relaunch, will they go to McGregor for that, or will there be an upper stage test stand at the cape ?
« Last Edit: 05/11/2017 03:02 PM by macpacheco »
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Online AncientU

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #365 on: 05/11/2017 07:15 PM »
Any opinions, when will SpaceX eliminate Static firing in McGregor and/or on a launch pad?
I think they'll keep all test firings in McGregor for new boosters. The goal is to fly them at least 10x moving forward, and eventually the "flight proven" mantra is likely to be proven with stats, that creates the interesting conundrum that if new boosters are slightly less safe than reused ones, they must be tested plenty.
Once a booster has been recovered, it has been to hell and back, as long as it shows no sign of damage, it only gets the pre launch static fire.

Which creates an interesting challenge, once upper stages are recovered, they probably should be test fired before relaunch, will they go to McGregor for that, or will there be an upper stage test stand at the cape ?

According to SpaceX, the pre-launch static fire is going away.  haven't heard the same for McGregor firing of new cores.

My bet would be on pre-launch static fire to disappear for reused boosters after the first 5-10 Block 5 reflights, and for all Block 5s soon after that.  With the 24 hour 'refurb' target, there isn't time for much of anything but getting the booster back into the HIF.
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Offline IanThePineapple

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #366 on: 05/11/2017 07:24 PM »
Any opinions, when will SpaceX eliminate Static firing in McGregor and/or on a launch pad?
I think they'll keep all test firings in McGregor for new boosters. The goal is to fly them at least 10x moving forward, and eventually the "flight proven" mantra is likely to be proven with stats, that creates the interesting conundrum that if new boosters are slightly less safe than reused ones, they must be tested plenty.
Once a booster has been recovered, it has been to hell and back, as long as it shows no sign of damage, it only gets the pre launch static fire.

Which creates an interesting challenge, once upper stages are recovered, they probably should be test fired before relaunch, will they go to McGregor for that, or will there be an upper stage test stand at the cape ?

According to SpaceX, the pre-launch static fire is going away.  haven't heard the same for McGregor firing of new cores.

My bet would be on pre-launch static fire to disappear for reused boosters after the first 5-10 Block 5 reflights, and for all Block 5s soon after that.  With the 24 hour 'refurb' target, there isn't time for much of anything but getting the booster back into the HIF.

I wouldn't be surprised if they did a dry dress rehearsal in the HIF to save time but also to check the stack preflight
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Offline Space Ghost 1962

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #367 on: 05/11/2017 07:38 PM »
Static fires at pad and stage testing at McGregor do different things.

Static fires (and WDRs) are rehearsals for launch by the launch team.

Stage testing validates systems under test conditions/instrumentation, where you can tear down if there's an anomaly present.

The first asks the question, "Can I launch this booster?" with my processes. The second asks the question "Is this stage operating as expected, perhaps even outside of its margins, as a vehicle for use?".

If you believe they can step-up to doing 24 hr "gas n go", they are doing repeated "can I launch this booster" back to back by launching the booster.

If they have any doubts, its no longer a qualified booster, and perhaps back it goes for McGregor for them to ask "is this stage operating as expected" again.

Online AncientU

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #368 on: 05/11/2017 11:25 PM »
The need for WDRs goes away if you are launching weekly or more frequently, unless there are unique characteristics of the satellite.
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Offline Lars-J

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #369 on: 05/16/2017 05:56 AM »
After 4 and half months of 2017, the launch stats look interesting:
(Data from Ed Kyle's great Space Launch Report - http://www.spacelaunchreport.com/log2017.html#log )

Quote
Vehicle            Overall
                   Launches
                  (Failures)
===============
Falcon 9              6(0)
Atlas 5               3(0)
R-7                   3(0)
Ariane 5              2(0)
CZ (DF-5)             2(0)
H-2A                  2(0)
Delta 4               1(0)
CZ-7                  1(0)
GSLV                  1(0)
PSLV                  1(0)
Vega                  1(0)
KT-2                  1(0)
KZ-1A                 1(0)
SS-520-4              1(1)

Quote
Vehicle            Overall
                   Launches
                  (Failures)
===============
United States        10(0)   <-- 6 of those being SpaceX!
China                 5(0)
Europe                3(0)
Russia                3(0)
Japan                 3(1)
India                 2(0)

If SpaceX was counted as its own country, it would beat all other countries.  :o And SpaceX is only warming up... There could be 5 more F9 launches before the end of July!  8)
« Last Edit: 05/16/2017 06:11 AM by Lars-J »

Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #370 on: 05/19/2017 07:56 PM »
If F9/FH upper stage could coast for several hours, would performance to GTO improve if launches used a 98% east heading, with just a tiny southerly component so the upper stage would only get to the Equator past Hawaii ?
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Offline intrepidpursuit

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #371 on: 05/19/2017 08:35 PM »
If F9/FH upper stage could coast for several hours, would performance to GTO improve if launches used a 98% east heading, with just a tiny southerly component so the upper stage would only get to the Equator past Hawaii ?

A circular orbit, by nature, is going to pass the equator halfway through its orbit.

Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #372 on: 05/19/2017 10:16 PM »
If F9/FH upper stage could coast for several hours, would performance to GTO improve if launches used a 98% east heading, with just a tiny southerly component so the upper stage would only get to the Equator past Hawaii ?

A circular orbit, by nature, is going to pass the equator halfway through its orbit.
Yes, I know, but that's not the question.
The question is if instead of using, let me guess a parking orbit heading about 15 degrees south of true east, if an orbit just 1 or 2 degrees south of true east is used, and the upper stage can coast until that parking orbit intersects the equator, would this require less total DeltaV for GTO-1800 or a super sync injection ?
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Offline Herb Schaltegger

Re: General Falcon and Dragon discussion (Thread 14)
« Reply #373 on: 05/19/2017 10:26 PM »
If F9/FH upper stage could coast for several hours, would performance to GTO improve if launches used a 98% east heading, with just a tiny southerly component so the upper stage would only get to the Equator past Hawaii ?

A circular orbit, by nature, is going to pass the equator halfway through its orbit.
Yes, I know, but that's not the question.
The question is if instead of using, let me guess a parking orbit heading about 15 degrees south of true east, if an orbit just 1 or 2 degrees south of true east is used, and the upper stage can coast until that parking orbit intersects the equator, would this require less total DeltaV for GTO-1800 or a super sync injection ?

That's generally what they do already, unless the vehicle has excess performance and a guidance system designed to lets them launch into a different azimuth and do yaw-steering into the desired plane as part of the ascent.
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Offline envy887

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #374 on: 05/19/2017 11:00 PM »
GTO launches already head due East. If they launch at a more southerly azimuth, it actually increases the inclination of the parking orbit. Parking orbits lower than 28 degrees can't be reached from KSC (at least without a very expensive plane change after coasting to the equator).

Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #375 on: 05/20/2017 01:21 AM »
I don't get it, which is certainly a result of my ignorance about orbital mechanics. When you think you understand it, you find you don't yet...
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Offline envy887

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #376 on: 05/20/2017 01:38 AM »
Look at the ground track of a 28 degree orbit. What direction is it traveling as it travels out the Cape?

If it launches with a more southerly azimuth, the track will sweep further south, then further north... That's a higher inclination.

https://spaceflightnow.com/atlas/av038/images/map_full.jpg

Offline ClayJar

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #377 on: 05/20/2017 01:57 AM »
GTO launches already head due East. If they launch at a more southerly azimuth, it actually increases the inclination of the parking orbit.

The way I try to explain that to people is to imagine it with the earth not spinning (meaning you'll always pass right over the launch pad after one orbit).  If you launch pointed anywhere north of due east, you'll obviously immediately be north of where you started.  On the other hand, if you launch pointed anywhere south of due east, you'll be coming back over the pad from behind you, i.e. north of where you started.

And of course, it's *really* obvious if you take it to the extreme and launch due south, as you'll go over both poles just as you would launching due north on our non-rotating planet.  The only direction where neither your face nor your back is pointing at all northerly is due east/west.

Offline cppetrie

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #378 on: 05/20/2017 02:11 AM »
GTO launches already head due East. If they launch at a more southerly azimuth, it actually increases the inclination of the parking orbit.

The way I try to explain that to people is to imagine it with the earth not spinning (meaning you'll always pass right over the launch pad after one orbit).  If you launch pointed anywhere north of due east, you'll obviously immediately be north of where you started.  On the other hand, if you launch pointed anywhere south of due east, you'll be coming back over the pad from behind you, i.e. north of where you started.

And of course, it's *really* obvious if you take it to the extreme and launch due south, as you'll go over both poles just as you would launching due north on our non-rotating planet.  The only direction where neither your face nor your back is pointing at all northerly is due east/west.
I think part of the reason it messes with people is because they don't consider the effect of the tilt of the earth axis. Without it a launch straight east would never cross the equator. However, with a tilt the ground track becomes sinusoidal and crosses the equator. Launching with a southerly heading gets you to the equator faster but means a higher inclination for the reason you point out above. Instead you launch straight east and let the tilt of the earth's axis do the 'work' of getting you to the equator. At least that's my pre-K understanding of orbital mechanics.

Edit: Please correct me if my understanding is incorrect and I actually don't even qualify for pre-K yet. Thanks.
« Last Edit: 05/20/2017 02:13 AM by cppetrie »

Offline Lars-J

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Re: General Falcon and Dragon discussion (Thread 14)
« Reply #379 on: 05/20/2017 02:31 AM »
I think part of the reason it messes with people is because they don't consider the effect of the tilt of the earth axis. Without it a launch straight east would never cross the equator. However, with a tilt the ground track becomes sinusoidal and crosses the equator. Launching with a southerly heading gets you to the equator faster but means a higher inclination for the reason you point out above. Instead you launch straight east and let the tilt of the earth's axis do the 'work' of getting you to the equator. At least that's my pre-K understanding of orbital mechanics.

Edit: Please correct me if my understanding is incorrect and I actually don't even qualify for pre-K yet. Thanks.

No, the tilt has nothing to do with it. It is basic gravity. Think of a extreme case near the North Pole. Launching straight east, will you just have a short circle above the pole? No, all orbits cross the equator.

Ignore the poles and equator. Whatever direction you launch, you'll continue straight, all the way around, always coming back over where you launched. (If the earth did not rotate)
« Last Edit: 05/20/2017 02:40 AM by Lars-J »

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