zolotiyeruki
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Posts posted by zolotiyeruki
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31 minutes ago, magnemoe said:
Does the arm has to move much? Superheavy can move pretty well and will have the hot gas thrusters for this, I don't see trying to counter with an arm will help much.
Now having some suspension on the arm would be nice and this has to be an downward motion not tilting as in flexing the arm.
Yes you could put hot gas thrusters on the arm, problem is that its hard to move heavy stuff fast.Hard? Actually, no. It just takes beefier equipment. Really big hydraulic rams, with really big pumps behind them. I'm reminded of a job I had several years ago, where a large work barge (probably 100x250ft) was next to a big oil platform. The barge's thrusters kept it quite precisely aligned with the mostly-stationary oil platform, despite the motion of the waves.
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7 minutes ago, SpaceFace545 said:
So all of y’all just said that spacex is able to do it and that’s the reply I have gotten on most of my criticism but that doesn’t prove anything.
What we'all are saying is that SpaceX have a history of taking ideas that sound a bit on the far side of crazy to doubters like you, and then making them happen, while you consistently post doubts that appear to be founded on nothing but intuition.
The shoulder analogy fails on even a superficial level. It'll be a hinge, not a ball and socket joint. It'll be made from steel or titanium, not bone and cartilage. Super heavy can hover, or nearly hover, when empty, while the human body does not have that ability. The catching tower will have shock absorption, if not outright active suspension, while the steel beams in your analogy do not. -
3 hours ago, StrandedonEarth said:
Nah, that should make it green and looking like a giant Kerbal catching the booster
Call it “The Jeb Tower,” or simply, “Jeb”
I wanna see a SH painted as a kerbal!
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2 minutes ago, JoeSchmuckatelli said:
@mikegarrison might have input. I've read, but don't know for sure, that high-altitude airliners while pressurized are not actually holding sea-level pressure while in flight. Perhaps there's a structural reason beyond keeping the minimum pressure required to keep the cargo alive.
I can answer that. Airliners are typically pressurized to about 8,000 feet. That's a high enough pressure to keep everyone alive and cogent (10,000 ft is where some people start getting hypoxia), while decreasing how much pressure the fuselage has to maintain. Atmospheric pressure at 35,000 ft is about 3.5 psi, at 8,000 ft it's about 10.9, and at sea level, 14.8. Instead of withstanding (14.8-3.5 = ) 11.3psi, the fuselage only has to hold up to (10.9-3.5=) 7.4psi.
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4 hours ago, wumpus said:
That's mostly true, but the merlin engine was designed for Falcon [1], which they never really attempted to recover. Future plans for both Falcon [1] and Falcon 9 were based around parachutes. Oddly enough, the merlin engine doesn't appear to have had issues lighting while falling with air blasting into the nozzle while the raptor engine (which was designed with retropropulsion in mind) has crashed a few times thanks to failing to ignite while falling.
...
Don't forget, "plan A" not only failed for recovering boosters (parachutes), it also failed for fairing recovery (catching it in nets). Plan B (fishing it out of the water) is working well enough that plan A was scrapped.
So while you might claim that Spacex was "lucky" that merlins have a property that was never a design goal, recovery appears to be more due to a dogged insistence of solving the problem than pure luck. The original recovery plans wouldn't work (although presumably merlins *were* designed for long enough working life for reuse), and they simply kept at it. You shouldn't be surprised if some parts are eventually found to have the properties needed to solve the problem in *some* way (if not the original plan, i.e. parachutes).
I would argue that catching fairings in a net *did* work. SpaceX just came to the conclusion that making the fairings water-tolerant was a better approach.
Even if the Merlin engine wasn't originally designed for relight, I'd be shocked if its design hasn't evolved to better facilitate relight.
And Raptor's failures on landing have generally been the fault of the fuel tanks, rather than Raptor itself.
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15 minutes ago, magnemoe said:
I read the ULA reuse is to expensive as true for ULA. their problem is that they has to design and build an entirely new rocket to reuse the first stage.
SpaceX was lucky with their Falcon 9, as it was pretty easy to set up for reuse. 9 engines with an center one and as one vacuum version is used in the upper stage is was created to be restarted, their testing strategy also involves multiple test burns so engines was kind of designed for reuse from the start.
And they could develop reuse on the cheap testing on stages after they was used for paid missions.You're right that ULA would likely have to do a whole bunch of redesign in order to recover their boosters, but I wouldn't call SpaceX "lucky." Reusability was a primary goal from Day 1 for Falcon, and a whole lot of engineering (and money, and explosions) went into making that happen. As a disposable launch vehicle, F9 has been pretty doggone reliable from the beginning.
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When engaging in this sort of debate, it's helpful if you have a similar historical situation to refer to by comparison.
...and we do, at Cape Canaveral, where the ecosystem doesn't seem to be terribly bothered by the presence of the world's largest rocket launch complex.
Also, six acres is a drop in the bucket compared the size of the area it's in. Pull it up in Google Earth, and you can see just how small a footprint the SpaceX facilities are.
Also also, if SpaceX blow up a starship prototype, they scatter liquid oxygen, liquid methane, (or maybe a whole lot of CO2 and straight carbon), and stainless steel, plus a tiny fraction of other materials. With the exception of the "other materials," the local ecosystem isn't going to care--methane and oxygen evaporate, stainless steel isn't going to taint the environment, and the rest of the stuff is generally at the back of the rocket and stays on or near the
crashlanding pad. -
4 hours ago, Lukaszenko said:
It's indeed ugly and it looks old-school and like they patched it together with a hammer; it's certainly not winning any beauty contests and perhaps it never will.
I'll definitely agree that sending anything to space; many-billion dollar probes on many-hundred-million-dollar sweet-looking rockets in your examples, is indeed special. I'll argue however, that sending whatevertf you want, whenevertf you want, for a tiny fraction of the price is even more so.
It reminds me of the short story Superiority by Arthur C Clarke.
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3 hours ago, SunlitZelkova said:
I think it is intended to be similar to N1-L3 or Energia-Buran, but without the dash and reversed. So if Orion were to launch on Superheavy it would be Orion Superheavy.
Out of curiosity, are there any other rockets that use an adjective as a name? Sometimes when I see people discussing Superheavy it makes me think "Superheavy what?".
Is Superheavy a relative in name only to Falcon? So technically it is Falcon Superheavy, which makes more sense as there is Falcon Heavy.
"Heavy" and "Super" are terms used by Air Traffic Control when referring to particularly large aircraft--"Heavy" for aircraft over 300,000 lbs, and "Super" for two types: the Airbus A380 and the Antonov An-225
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43 minutes ago, GuessingEveryDay said:
@tater has the answer:
I didn't see anything there about the duration of the first stage burn, only that SpaceX are basically going to keep reusing boosters until they break.
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Is it normal for the 1st stage to burn until 2:35 or so? I was under the impression that MECO is usually around 2:20.
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If a hypothetical dragon landing burn failed, wouldn't the landing legs be moot? I mean, if a capsule impacts at terminal velocity, I don't know that having the landing legs retracted is gonna save the occupants.
Ah, I suppose if you had a mostly-good landing burn and the engines started just a bit late or cut out just a bit early, but that seems like a pretty narrow risk probability. Although I supposed Starship is proving me wrong, here. -
2 hours ago, mikegarrison said:
It's all a matter of cg location.
Unfortunately, for dynamic stability you want the cg to be toward the nose, while for stability standing on the surface you want the cg to be toward the tail.
At least on the Moon there are no wind loads.
The "cg toward the nose" is applicable if you're 1) in the atmosphere, and 2) intending to fly nose-first. Neither are true on the moon. The concern about CG on the moon is a valid one, though-- the SS prototypes up to this point have all been landing very tail-heavy, with nothing but empty space and a header tank in the nose. On the moon, there won't be a need for a header tank in the nose (no bellyflop), which should help shift the CG toward the engines, but it *will* have a whole bunch of cargo in the nose, which will shift the CG way up.
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1 hour ago, JoeSchmuckatelli said:
I'm reading this... and my first thought is, 'Here's why SX has been pushing out (and almost landing / crashing) so many Starships, so fast.'
The general public may not recognize that an 'almost land' and a 'did land, but blew up' is an amazing technical feat... but NASA engineers certainly do. So by getting so ever-freaking close to pulling off the miracle they're aiming for (as merely a stepping stone), along with their proven ability to reuse Falcon... the subconscious / unpublished reason SX got chosen wasn't merely cost, or reusability, or 'failed to comply with requirements' - it was belief that they could do what they offer.
"so ever-freaking close" is right. Honestly, the engines are doing pretty well, as long as they're properly fed. Sure, one caught fire on SN11, but SpaceX are iterating so rapidly that they can handle failures and slipstream the fixes into later models. Contrast this to SLS, where it absolutely has to work perfectly the very first time.
That rapid iteration really synergizes well with their design--welded sheet metal tanks/fuselages are cheap. Their goal is $250k per Raptor. Let's say they're at $2m right now. For a couple dozen million dollars, tops, they're getting to basically test the entire spacecraft through just about every regime, from launch to hover to flop to descent to flip to hover to landing, all in actual real space under real conditions. -
36 minutes ago, kerbiloid said:
Any known aerobraked cylinder?
Why did the shuttle have a lifting body bottom? Its fuselage was more or less cylindric.
And I believe that aerodynamics hasn't changed since 1960s.
The shuttle had a lifting body and wings because 1) one of the requirements was for 1000 miles of crossrange capability, i.e. it could land anywhere within 1000 miles of its intended target, and 2) it needed to be rapidly reusable (which never happened), and a horizontal landing had the potential for minimizing how much refurbishment was required before relaunch.
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If you're going to catch SS in a net, you could also add parachutes to slow the descent. Since stopping distance is proportional to the square of the starting speed, assuming constant deceleration, dropping the terminal velocity, say, in half would reduce the stopping distance by 75%.
The approach seems a bit odd to me, given SpaceX's decision to scrap a similar approach with the fairings. Of course, the fairings have a much lower vertical velocity, and are presumably much more susceptible to wind, and SpaceX have figured out how to fish them out of the ocean without damage.
I *would* be concerned about potential damage to heat shield tiles with a Giant Net approach.
How much lighter would SS be without the propellant needed for the flip, hover, and landing? How much would that affect its terminal velocity?
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Is there a corrosion issue with storing LOx in a mild steel tank?
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So....no big net to catch F9 fairing halves, but yes to a really, really big net for catching SS? That's gonna be somethin' to watch...
WRT the tanks, it might also just be a matter of "Hey, the welding crew has a couple days with nothing on the schedule. Since we're paying them anyway, why don't we get them to build us a GSE tank?"
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5 minutes ago, tater said:
I'm still unable to stop thinking about this.
Shipping oversize loads in the US can run "well in excess of $10/mi" according to a company that does that for specialized gear, but they also quote $3/mi as being common (those are surcharges past the normal base per weight I assume). Even if it cost $100/mi to ship the tanks available for sale in McGregor to Boca Chica, that's only ~$100k each. No idea what the tanks cost, but it can't be that much more than the alibaba price, right? 2X and $50k in shipping and it's $100k total cost, times 4.
That makes a Starship "hull" (tank? fuselage?) cost under $1,000,000, and SH maybe 1.5M$.
<blink>
It may also be an issue of delivery timing. With the pace of fabrication on-site, SpaceX may have realized that, setting cost aside, it would be faster to build their own tanks than to bid it out, select a supplier, wait for the supplier to get the materials, fit it into the supplier's schedule, and then somehow ship a 9m-diameter tank across some distance. Time is money, after all, so even if it ends up being more expensive, they'd get it WAY sooner, and wouldn't have to worry about the specs/requirements being misinterpreted.
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3 hours ago, sevenperforce said:
One of Von Braun's ideas was to build "floors" into the interior of the terminal stage, with all of the floors being built out of an open grid which would be lightweight and would also allow the propellant to drain through. That is only a slight drop in propellant capacity and at least, gives you a rough sort of internal organization. But then -- what do you even do with the space?
Well, I suppose all the accoutrements could be packed into the payload section, as you'd do with a moving truck, and then unpacked into the larger volume once it's in orbit and the fuel has been vented. It'd be a bit like building a house from the inside.
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19 hours ago, kerbiloid said:
Space Shuttle also had the SpaceLab, which was amusingly complex being compared to the dimensional expectations.
Skylab and all Soviet stations and modules are fuel tanks with windows. So, the Starship could be a 9-m wide one.
I LOVE the idea of using spent SS's as a space station, but question the cost. I mean, the whole raison d'etre of Starship is reusability, which entails bringing it back down to earth to save money. If you just leave it in LEO, that sorta defeats the purpose. Is there a way to loft large, empty vessels into orbit AND bring SS back to earth? Deployable somethings like that inflatable module they put on the ISS? Some way to decouple the engines and avionics from the tanks, and then recover the expensive bits?
Or, since they're currently just disposing of F9 second stages, maybe they could modify that design so it could dock with some sort of truss, and the F9S2 tanks could be finished into hotel rooms. Eh, if you're going through that much trouble, it'd make more sense to just load four cylindrical, purpose-built, pre-finished hotel room modules into a SS and launch 'em that way.
Or just design your new space station to use 8m-diameter modules, and launch 'em on SS.
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1 minute ago, magnemoe said:
This, you only have fuel in the header tank then landing. Now you could offset the header tank but this would change CoM more sideways during landing.
And the LOX header tank in the nose shifts the CoM higher, away from the engines, making the gimballing even more effective
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Given that they're planning to land on 1-2 engines anyway (i.e. center of thrust is offset), plus the gimbal range, I'm not particularly concerned about the small shift in CoM due to the tiles. Besides, if you double-hull the windward side, that would shift the fuel leeward, but you'd be adding a whole second layer of stainless steel on the windward side, too, therefore adding more weight where you don't want it.
[1.10.x] Precise Editor 1.4.0.1 [August 31 2020]
in KSP1 Mod Releases
Posted
I'm having trouble understanding what you're looking for here. Can you elaborate a bit more?