Nefrums
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Posts posted by Nefrums
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While we wait. Have anyone seen a flight plan?
From what I have read there will be a 6 hour cruse before the exit burn.
My guess: Factoring in the time of day of the launch and the fact the the exit will be in the general direction of earth prograde it does not look like they will go to GTO but rather a shorter 6 hour elliptic orbit followed by a exit burn close to PE.
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Btw are they planing to stream the ejection burn? I guess it will not be the same stream as that would be a 6+ hour stream then
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3 minutes ago, Scotius said:
"Clock management"? What in the space does that mean?
Probably that they will time the launch to one of the preprogrammed fight patch to get into the right orbit and get the right ejetion angle.
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1 hour ago, sevenperforce said:
Not sure separation will occur low enough for aerodynamic forces to have much effect. But if they did, they would most likely not cause significant rotation around the CoM, not enough to make a collision likely.
Keeping the adjacent engine burning through separation would certainly do the trick, but I don't know that they'd attempt something that risky.
After thinking more about it it is as simple as using the cold gas thruster at the top to push away and at the same time use the engine gimbal to prevent any rotation. Then both the engine and the thruster will push the booster away in a controlled way.
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14 hours ago, softweir said:
Announcements so far indicate that the core booster will throttle-down for Qmax and to limit acceleration once fuel load is reduced, so in consequence the side boosters would run out before the core does. (The side boosters will, of course, separate before they are dry so they can RTLS!) The core is intended to continue thrusting after side-booster separation. The side-boosters will cut all but one engine, and use that engine and cold gas thrusters to assist separation.
As soon as the side boaters tilt away from the center the air pressure will push them away from the center. But as the CoM is far back this will also cause additional rotation.
I think we will see a small tilt away and then the still running engine will gimbal to keep the booster from flipping due to aerodynamic forces, this will at the same time punch the bottom of the booster away from the center stage.
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7 hours ago, CatastrophicFailure said:
Because they were waiting around in case they had to tow a booster back...
Given that we’ve heard zero about fairing recovery from SpaceX, I’m guessing it’s not quite ready for prime time.
The fact that we have not heard anything about faring recovery indicates that the fairings where not recovered. Hard to say if that is due to that they did not try or that they tried and failed.
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I really like the launch time. It is like prime time entertainment for us that lives on the other side of the pond!
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The Martian dust storms can be a problem for solar panels. But I still think that thin film solar panels are the way to go.
You just have to figure out a way of getting the dust of them.
I doubt that the storms can cause any damage or even move the panels. As Martian storms has half the wind speed of Earth storms, and combined with the 1% pressure, that means they only have 0,5% of the power compared to earth storms.
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will they stream the static fire? I cant find any..
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11 minutes ago, KSK said:
Static fire in T-minus 6...6...6..
Never put a clock inside a pentagram.
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8 hours ago, sevenperforce said:
Random aside: does anyone have any idea how the proposed BFS is supposed to do the flip from prograde to retrograde for the landing burn?
I've tried modeling it, and...yuck.
It has to have CoM an CoL close, and have a powerful rcs system.
The landing burn propellant tanks is far back, inside one of the main tanks.
They probably have to light the engines halfway through the flip to gain more control through gimbal.
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What I meant is that the launch clamps only have to deal with a 0.5 G load after ignition, compared to the 1 G load before ignition. Most of the engine thrust is countered by the rockets weight.
Unless they run the static fire with partly empty tanks?
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12 hours ago, KSK said:
Ahhh, that would explain it. My previous jests notwithstanding, they don't want any problems trying to hold down 5 million pounds of thrust.
If the launch clamps are able to hold the rocket up before the engins start, they should have no problem holding it down after ignition.
With a twr of 1,5 the force the launch clamps have to hold down is only half of what the have to hold up before ignition.
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Just making the fuel tank of the second stage larger makes more sense.
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14 hours ago, Laie said:
I know that 4600m/s for Tylo landing and ascent is quite tight. Do the other figures have a similarly small margin of error?
Yes, And 4600 is a Tylo landing with good twr. Lower twr means more gravity losses.
It is possible to do the transfers from LKO to low tylo orbit and back with a single ion engine. Just add ~1000ec of batteries and a rtg. But that would mean several hundred 2min pe kicks.
I have flown that with a <10t ship, and even that required ~20 PE kicks to escape kerbin.
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18 hours ago, Cunjo Carl said:
Can I ask how you sussed the 1050m/s LKO to Tylo? Did that involve any gravity assists or was it just for the simple transfer?
That is when taking PLADs K-E-K-K-J route
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This would require a lot of dV, even with gravity assists
LKO -> Tylo: 1050m/s + another ~ 7-800m/s to get to low orbit.
Tylo landing: ~4600 m/s
Low Tylo orbit -> kerbin ~1000 m/s
So you would need to have ~7.5 km/s left in LKO. probably doable with ions, but you need twr for the tylo landing.
I would say that this is not possible, but still worth a try.
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If the BFR gets cheaper than the F9 per launch there will be no need to use F9 for smaller payloads.
Imagine what that would mean for the cube sats launch costs.
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This is hard, but possible. I did this back in KSP 1.1
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About the supposedly reusable heat shield on the BFR ship, are there any examples of heat shields that have been reused without extensive refurbishment today?
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20 minutes ago, TheEpicSquared said:
SpaceX should have a naming competition. Winner gets a free tour of the HQ or something.
"Rocky McRocketface"
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The first question boils down to who is the most likely to get the funding required to do a manned mars mission.
As had been said before the incentive to fund a mission like this is ether the pride of nations or the egos of billionaires.
Space X will try to raise the funds they need by them self. This sounds impossible, just like many of the other thins Elon has done..
NASA will not get the funds it requires, unless it looks like some other country is getting there first.
CNSA is more likely to be funded as the pride of the nation is still a big thing over there. And Chinas economy will be vastly larger then any other countrys middle of next decade.
I think the only thing that could trigger a manned mars mission before 2030 is if there is a second space race between NASA ans CNSA in the next decade.
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2 hours ago, CairoJack said:
Easily ?!!!
He he.
I meant that a ship can easily fit into the vab.. Not that it would be easy to build it.
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Of course it is possible, a few have done this already. Look at the ultimate challane threads.
And a ship to do this can easily be built in the VAB.
SpaceX Discussion Thread
in Science & Spaceflight
Posted · Edited by Nefrums
did SpaceX try a new landing procedure for the center core?
Landing is normally done on one engine, Side boosters landed with one engine.
Last week they tried a new shorter landing burn with three engines for soft splashdown on a expendable launch.
Now we hear that the core failed to land because only one out of three engines started...