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If I understand correctly, the Omnicalculator is the item I looked at, which does trajectory predictions in vacuum. If so, the lack of drag is exactly why it shows higher altitudes by a long ways. The velocity at that altitude will also be way too high. I would expect the velocity lost to drag would be at least 1000 mph, and I would not be surprised if it were closer to 2000 mph. And there is still KE to trade for PE.
As for a metal nose tip, at 5000 mph the stagnation temperature of the plasma that was air would be in excess of 5000 F. Even tungsten is liquid at that temperature. Right at the stagnation point on the nose tip, the metal will get quite close to that temperature, within a second or so. You are far better off with an ablative nose tip that you can replace, and there is no problem using a nose tip radius that is nonzero, to cut down the erosion rate. People do it all the time.
GW
Two points:
1. Dare trust nothing off an internet unpoliced for truth. Twitter (among very many) has long been notorious, and now as X, it is even worse.
2. Booster probably fell over sideways onto the sea after touching down, with a bit of propellant still aboard. Not being designed for that, it probably broke apart upon smacking the water sideways. An explosion would be expected.
Meanwhile: the hurricane came ashore closer to Houston than Brownsville. SpaceX seems to have dodged that bullet. I did see one comment somewhere on somebody's news feed: Musk wants to fly in 4 weeks. But as I said in point 1, I'll believe it when I really see it.
GW
Once you are very high supersonic to hypersonic, the sharp nose vastly increases the stagnation point heating. The old correlation H. Julian Allen used for warhead entry was Q/A = constant*[(amb.density/nose tip radius)^0.5]*velocity^3 for convective heating. This model goes infinite as tip radius goes to zero. That model behavior trend is quite accurate: experience very clearly shows that nothing sharp survives at entry speeds, and stays sharp.
Heating does not vary in proportion to overall drag, it varies proportional to skin friction drag. Sharper noses do reduce overall drag, because they reduce pressure drag. Heating varies with skin friction drag, which is a very minor and negligible component of the total nose drag at supersonic speeds. Pressure drag dominates over skin friction by far, at such conditions.
I feel qualified to say those things because my engineering master's degree was in high speed aerodynamics, to include heating. The BS that prepped in specialized in aerothermodynamics and propulsion (says so right on the diploma). I went to work with those degrees and did those very things for a competitive living in the defense industry.
The doctorate I earned late in life, after the defense career was over and I was doing a lot of teaching and some civil engineering. I studied manufacturing for it, but did my dissertation on by how much (and more importantly, why) ethanol and ether burn more efficiently in piston aircraft engines than gasoline does. It shows up on the dynamometer, and in flight.
GW
Looks like Beryl is going to come ashore somewhere close to Brownsville/Matamoros. That means SpaceX is going to see the winds, storm surge, and rain. If I were them, I'd pull my flight hardware inside until this passes.
GW
I would love to see a "shipyard" started in the form of a repair and maintenance bay of some kind. Building a pressurizable one is a real problem still, but building an unpressurized one is not! That's a space frame of light pipe or tubing, covered with space blankets, and with banks of electrically-powered lights inside, hanging on that space frame.
This space frame bay needs to attach to "something", which "something" also has the fittings to hang onto the vehicle being serviced, and also other fittings to provide a "footing" for the crew doing the servicing. Visibility is not an issue with the lighting. Temperatures are also not an issue, with the space frame covered, so that neither the sun nor deep space can be seen. Workpiece temperatures are controlled by the power of the lighting. It is a radiational balance thing.
If the servicing crew were using MCP suits, they could be far more effective, especially if these suits were of the vacuum-protective underwear type that were shown feasible back in the 1960's by Dr. Webb. Inside the temperature-controlled bay, there is little need for heavy insulating garments. It is even possible to doff the gloves and do very delicate fine work barehanded, for up to about half an hour at a time.
My first notion of this concept, without the protected bay, was posted on my "exrocketman" blog site 2 August 2011, as "End of an Era Need Not Be End of a Capability". I updated this with the enclosed, lighted bay (unpressurized) in an "exrocketman" article 11 February 2014, as "On Orbit Repair and Assembly Facility".
GW
The reporting on this is so lousy that you really have to hunt hard to figure out what is really going on. They cannot open up the spacecraft on orbit in a spacewalk, and look inside to see what is going wrong. It is simply not built to be serviceable. All Butch and Sunni can do is go run tests from the cockpit and report the data to people on the ground. Period.
Meanwhile, Boeing and NASA on the ground have been running some sort of simulations on the ground, in some sort of representative hardware, trying to duplicate what Butch and Sunni are seeing in their tests. I have yet to see anything that would provide the identity and nature of that ground test hardware.
They cannot bring the malfunctioning hardware home to open it up and find out what really went wrong. The troubled systems (so far) have been in the service module, discarded for entry, and lost. That begs the question of what might go wrong in the entry capsule itself. That was built by the same Boeing, and it also has essential attitude thrusters to prevent a tumble during entry, and those are the same type of hypergolic bipropellants, pressure-fed, as what's on the service module, powered by the same type of helium pressurant.
So far, after a month, they clearly have been unable to figure out what actually went wrong on the flight vehicle, or why. They are now planning to keep Starliner at the station past the nominal 45 day battery life (the same battery life expiration that stopped one of the launch attempts). Supposedly, the batteries are being charged at ISS, extending the time before they become untrustworthy (although that didn't seem to be an option for the launch attempt, as I recall).
I really do not like what I see happening.
My opinion: Leave the thing at ISS until there is a Starship flying well enough to come get it and take it home intact. That may be a year or so in the future, depending upon how soon SpaceX can solve the remaining troubles and actually equip one of these prototypes with a real cargo deck, payload door, and handling gear. Bring the Starliner crew home in a Dragon now.
Reality: they will delay until they have no choice (batteries starting to fail). Then they will risk the crew's lives coming home in a spacecraft so very clearly not yet ready to be man-rated.
Prediction: And we WILL see thruster issues pop up on the entry capsule, during that entry to bring the crew home. If the failures get bad enough, the capsule may tumble and break up, killing the crew. And we will see another attempted cover-up during the inquest hearings, should that happen.
GW
Tom:
I found the link in the SSTO section, and followed it to something posted on X that said and showed NOTHING, which in turn led to a posted article elsewhere, about European space. Specifically, a new start-up in Italy.
In that article there was not one single word or number about the Isp they achieved, only a burn time of 11 sec! There were words about a stage length of 4.2 m long, and a payload of 13 kg. And that is all there was! They have not yet flown at all. There was absolutely nothing (!!!) in the article about what their propellant might be.
What I showed with my bounding calculations was that anything over about 450 s could indeed be an expendable (only!!!) SSTO at a competitive payload fraction, at an inert mass fraction in the 4-5% range. There is not now, and never will be, anything reusable from orbit in that inert mass fraction range! You need a heat shield and more structural beef to bring it back from orbital speeds. Those are heavy! End of issue!
I used inert fractions in the 10-15% range (should probably be nearer 20%), and showed you must have well over 600-700 sec Isp to do the orbit and return in a single stage, even at 0% payload fraction! Which is entirely unattractive from a business earnings standpoint!
I'm pretty sure those results of mine are correct, and I'm also pretty sure any claims otherwise are BS, marketing hype, or plain advertising fraud, pure and simple (of which there is a lot out there on an internet entirely unpoliced for truth, especially X of late). Those 3 terms are synonyms, by the way.
GW
The 5000 mph speed and ~45 degree path angle apply at the moment of release from the spin launcher. That is NOT where the rocket fires! Not by a long shot!
The carrier vehicle is streamlined to coast up along a path of decreasing speed and path angle as altitude increases, that is an un-thrusted but very draggy gravity turn. Artillery shells follow a similar trajectory, except that most of them never leave the lower atmosphere. Most of the drag loss is way down deep in the atmosphere, even with spin launch, just like with an artillery shell, only worse, because the "muzzle velocity" is so much higher.
That trajectory reaches a near-zero path angle (essentially no vertical velocity component, but some significant horizontal velocity component) by design outside the sensible atmosphere, which if hypersonic, would have to be significantly above 100 km. If only supersonic, could be as low as 60-80 km. If not at orbital altitude (near 300 km), there is still a nonzero path angle that is required.
THAT is the point where the rocket fires, which puts it on approximately a surface-grazing or near-surface grazing ellipse with apogee at the desired orbital altitude. Depending upon the velocity (vector!!!) at the rocket ignition point and the rocket Isp, it may take 2 stages to reach the required velocity somewhere fairly early along another gravity turn, finally putting it onto the ascent ellipse.
If the launch from the spin device was at 5000 mph, this near-apogee rocket firing point will have a speed WAY BELOW that value! It is inherent, because of the super-high drag while at terrific speed very low in the atmosphere, and also "conservation" of mechanical energy: you must trade off KE for PE as you ascend. It's not exactly "conservation", because your sum of PE and KE is steadily decreasing as drag robs you of energy. There is NO WAY AROUND that little ugly fact of life!
But even that is NOT YET orbital entry! This is the same sort of automatically-reentering trajectory that two Starships have now flown. You have to a make a final burn for orbital entry to circularize at the ascent path apogee. That burn is on the order of 100 m/s dV here at Earth. Closer to 50 m/s for low Mars orbit.
And that completely ignores the question of maneuver to rendezvous and dock with the final destination.
It also completely ignores the dV required to de-orbit for proper disposal, so as not to create more space junk. That's about the same as the circularization dV, since you just get back onto a transfer ellipse whose perigee is at or near the surface, deep in the atmosphere.
This kind of ascent trajectory is only grossly similar to a TSTO ascent trajectory, in that each bends over horizontal as it finally arrives at orbit altitude. Down low in the atmosphere, they are quite different: one is at high speed and un-thrusted, the other is at very low speed and thrusted pretty hard. You will not see the correct ignition conditions for the spin launched rocket on a TSTO launch trajectory!
The rocket equation DOES NOT APPLY to ballistic trajectories without thrust! It ONLY applies to that portion of the spin launch trajectory where the rocket actually gets used. I have seen NO data in anybody's videos or writings saying what the flight conditions are at the rocket ignition point.
This is simply NOT the sort of thing you can do with a simple spreadsheet; this takes a real trajectory code. One with a real full aerodynamic drag model, a real design's weight statement(s), and a real model of the rocket thrust(s) vs time, in 2-D polar coordinates at least. Could be a point-mass type model. If it's 2-stage, there are weight statements and thrusts to model for each stage.
Even then, you still have to do the circularization burn, and you must somehow deal with rendezvous, and with deorbit for proper disposal.
GW
Rocket equation analysis makes ABSOLUTELY NO sense for the "first stage", that being where the carrier ends up launching whatever it contains. There would be speed, altitude, and path angle data for that point, and I have NEVER seen any credible data, not yet.
From that point, you could do rocket equation analyses of however many stages the rocket has, that pushes the actual payload into orbit from there. But you have to make some educated guesses for what the gravity and drag losses might be. And they would be only guesses.
GW
Solid or liquid, the components must be supported and stressed for centrifugal gee in the 10,000 gee class. It appears with the angled launch, they do not intend to recover and re-use the carrier vehicle. BTW, its pointed nose will be blunted by air friction heating on the way up. Sharp points do not stay sharp in hypersonic flow.
GW
PS -- that last sentence is also why I do not believe you can build an air inlet for high hypersonic flight in the atmosphere, or for flying into space with airbreathing propulsion. If the sharpness goes away, so does the inlet pressure recovery, and its mass ingestion characteristics. Its drag also goes up; a lot!
Not to mention that thrust is a factor times ambient air pressure, with any imaginable type of airbreathing jet engine. 10 times nothing is still nothing, no matter which way you try to "spin" the situation. No thrust is simply no climb rate and/or pathwise acceleration. Isp doesn't matter once that obtains.
They'll have to find some way around the leak hazards of toxicity and fire/explosion. Probably off-loading those propellants, and venting the tanks and plumbing to vacuum for a day or so, before bringing it inside for work.
Those hypergolic storable propellants for extremely-simple and utterly-reliable (except Starliner) thrusters are just too attractive. If you do LOX-LCH4, you can do them pressure fed, down at under-100 psia chamber pressures, but you must ignite the burn with "something". In vacuum. Cold.
About the only thing that I know works as that "something" is TEB injection just as the LOX flow begins, during which you start the methane. TEB is every bit as serious a toxicity risk and fire/explosion hazard as NTO and any of the hydrazines. And there is the enormous difficulty of utterly-precise timing. And the resulting more ragged-looking pressure & thrust traces with time.
There is a reason they use NTO/any of the hydrazines, despite the risks of toxicity and fire/explosion: it really works quite well, very simply and easily, and with good performance, including a nice clean ignition and a clean cut-off. And with small thruster propellant tanks, you can afford the weight of higher tank pressures, resulting in higher chamber pressures (100 psia and up) and the resulting better performance out of the thrusters (not CFvac, but c* is a function of Pc, with Isp proportional to c*).
GW
From AIAA’s “Daily Launch” for Monday 7-1-2024:
ARS TECHNICA
NASA orders more tests on Starliner, but says crew isn’t stranded in space
NASA and Boeing officials pushed back Friday on headlines that the commercial Starliner crew capsule is stranded at the International Space Station but said they need more time to analyze data before formally clearing the spacecraft for undocking and reentry. Commander Butch Wilmore and pilot Suni Williams will spend at least a few more weeks on the space station as engineers on the ground conduct thruster tests to better understand issues with the Starliner propulsion system in orbit.
My take on it:
No change at all in status. Just confirmation of my suspicions. Note the wording of the second sentence (there are two).
GW
The photo in post 75 shows the spin launch carrier vehicle, a streamlined dart. The side of it opens up laterally like a clamshell, to release the payload and its booster rocket. The clamshell closes and the dart falls back, finally slowed by a chute, for a landing near the launch site.
This kind of trajectory apogees in altitude (zero vertical velocity) with virtually-zero horizontal velocity. The payload's booster rocket has to take it from essentially zero speed to orbital speed, horizontally, in the desired direction. Since it is above the sensible atmosphere, and radius from the Earth's center is not changing during the burn, there are no gravity and drag losses to cover. Circular orbit speed up there is about 7.7-something to 7.8 km/s. A transfer ellipse from that point instead of just circularizing, has a higher velocity requirement.
In essence, the unpowered carrier dart has as its payload the actual payload, plus a booster rocket capable of delivering 7.8 km/s dV or more, while carrying that actual payload. That booster rocket will be quite a bit bigger than the actual payload. The rocket equation demands that.
Acceptable payload fractions and the booster stage Isp's determine how many stages are required. Bear in mind that to withstand 5000-10,000 gees laterally, the inert fractions for the booster stages are going to be much higher than you are used to seeing! Strength always costs more mass. It is inevitable.
While I hope they succeed, it is my opinion that the considerations I just described render the potential of this launch technique to be quite limited.
GW
An offset nozzle from motor centerline is a problem you can handle by making sure the nozzle axis points through the vehicle center of gravity (more complicated than it sounds, since the cg moves as you burn off propellant).
Any thrust axis that does not point right through the cg must be balanced by another opposing moment, and I do mean EXACTLY balanced! Any unbalanced moment WILL cause the vehicle to spin and tumble. That is NOT a feasible means to control or shape the trajectory.
GW
All the candidate spacecraft to repair use bipropellant hypergolic-ignition pressure-fed thrusters. The propellants are quite lethally toxic. What if you have a leak while you are trying to get into one of these craft to make repairs?
Even if you do an unpressurized (but enclosed and thermally stabilized) work bay, the leak risk is still a huge problem to solve. Residues get on your suit, and come inside the airlock with you. And if both species leak and touch, you have an explosion and fire.
GW
Hi Spacenut:
From what I understand, it is very difficult getting inside the service module to examine or replace anything. It has to go back to the assembly building and be demounted from the rocket, in order to do tasks like that before launch. You almost have to take it completely apart to get inside it at all. That's what the 45 day battery life thing is really all about. And that kind of work cannot be done hanging in zero gravity and vacuum, wearing space suits.
Any sort of small bay to work on things like that, needs to be able to close and pressurize. With the object firmly held, and supports for the work crew to "stand" on while exerting forces. Being enclosed and pressurized, temperatures can be controlled with the power of the lighting, so that technicians in street clothes can work bare-handed without risking thermal injury. And there is the inevitable risk of a toxic propellant leak, which would kill any such work crew.
A work space like that is a tall order to supply, especially one big enough to put a Dragon or a Starliner (or especially a Dreamchaser) inside. Besides the size and expense, I think the toxic leak is a killer for that concept.
Better to just do the high-quality design with careful attention to detail, so that these systems are simply very reliable. But you cannot rip the government customer off to make a high corporate profit, if you do these jobs "right". And THAT motivation is why Boeing did the crappy job it so apparently did on Starliner (and those airliners).
GW
Still no change for the Starliner crew that is supposedly "not stranded" aboard the ISS. The lack of change in the situation for over 3 weeks suggests nobody on the ground has yet figured out why all these troubles cropped up. Reporting on this is sparse, and from a technical standpoint, unreliable, but it appears the thrusters have some unspecified problem that causes the control software to lock the misbehaving thrusters out.
Pressure-fed bipropellant hypergolic-ignition thrusters are a technology that has been flying for over 6 decades now. There is no excuse for these troubles to be cropping up like this. But there might be a reason: crappy quality. The thruster technology is dangerous enough that you have to do it "right", in order to get reliable, safe results. "Right" means very careful attention to details, and very high quality.
Apparently 5 of the 28 on the service module "tanked" and got locked out, which is what delayed docking, because that was too many to lose, as programmed into the flight control software. They somehow manually restored 4 of the bad 5 thrusters, good enough to be able to override the control lockouts, and thus be able to dock. I may well be wrong, but I get the definite impression that thrusters are still showing up "unusable" in the software, and nobody can figure out why.
And, there's also the helium leaks, which threaten getting propellant into the thrusters. They flew with 1 small leak, but 4 more showed up on the way up, one which was actually very large. They may or may not yet understand what has been going wrong there, either, I dunno for sure. Only some of the reporting talks about flanges and seals. If so, there's no excuse for this, either. Even with easy-to-leak helium, the plumbing technology has been flying for over 6 decades now. Although a reason could be crappy quality.
Despite the press releases, NASA (and Boeing) have been very close-mouthed about all this trouble. I understand the delay, since there is no "smoking gun" hardware to look at, once the service module is discarded for entry after making the de-orbit burn.
What I'd hazard a guess about, is crappy quality building these things, forced by the same evilly-greedy corporate culture that screwed up the 737 MAX big time (killing 2 planeloads so far), and which has also screwed up the 777X and 787 programs, although those have yet to kill passengers.
Nobody has run into troubles with the entry capsule yet, so far. But that's coming! It was made by the same Boeing.
The batteries that power stuff aboard Starliner "time-out" after about 45 days, or so I heard. About half that time is now gone. If Boeing and NASA can't figure this out by then, they are faced with a choice fraught with consequences either way: either bring the crew home with untrustworthy batteries powering their capsule, or bring the crew home in a SpaceX Dragon.
Boeing management will likely push for risking the crew on bad batteries to avoid more bad publicity (to keep stock price from dropping further). And, after Columbia and Challenger, I do not trust NASA upper management to value crew lives above bad publicity. They didn't before, in either case, and actually attempted a cover-up during the Challenger investigation.
GW
Kbd512 is quite right.
There is some kind of car manufactured in India that uses a compressed air motor. As near as I understand, the range of the thing is quite limited, even compared to lead-acid batteries, much less lithium batteries. I could be wrong, but that is the impression I got reading about this air-powered car, some time ago, now. The brand name was Tata, or something pretty close to that.
Compressing the local atmosphere to usable pressures in such a device is way more difficult on Mars than here on Earth. It needs something like around 3-5000 psi to be practical, or around 200-300 standard atmospheres. On earth from near 1 atm ambient pressure, that's a compression pressure ratio of near 200-300:1. You do that with multi-stage positive displacement machines, and they are inherently heavy and power-consumptive. We call them air compressors.
On Mars you still need the same compressed pressure (200-300 atm) to make the air motors work the same way they do here, but the local ambient pressure is only in the vicinity of 0.006 atm. That makes the required compression ratio nearer 160 times higher than on Earth, or near 32,000 to 48,000 : 1. There is no way to do that with a positive displacement compressor. You will need a machine more closely resembling an extreme vacuum pump, infamous for very high power consumption at very little throughput massflow indeed!
GW
In any solid propellant motor, there must be a free volume in which to collect the gas coming off the burning surface, and then funnel it into the nozzle entrance. This same free volume affects c* efficiency (the "combustion efficiency"), because the stuff coming off the surface is not yet fully mixed or fully burnt. It's a residence time thing.
As for extreme gee, Spacenut is exactly right, if there is a path for the solid propellant to flow (like a liquid) out the nozzle, then it will flow out the nozzle under extreme acceleration. There is no such thing as a true solid. Under extreme temperature and extreme applied force, all materials flow like liquids. Only the detailed numbers vary from material to material.
As for asymmetry, that affects the moments applied, for forces off axis. This can be quite the severe effect.
GW
Bob:
I'm not sure what the modern consensus is, being long retired from the rocket and ramjet business. But long ago, in the 1970's-early 1990's, the consensus was about Mach 6 as the speed limit for subsonic combustion ramjet. That's a fuzzy number for a limit, and Fred Billig at JHU-APL thought it might be closer to Mach 7. Fred is no longer with us, but I sat in a hotel bar swapping ramjet tales with him in 1987.
The real problem is what kind of models can you use for a design analysis as the speed exceeds about Mach 6? The inlet air is becoming hot enough to start ionizing, at which point it is no longer really air, and the standard compressible flow analyses begin to fail, because their fundamental assumptions are being violated.
Something similar is happening in the combustor at about that same fuzzy speed, where the energy release of combustion is no longer just going into gas internal energy, but also into its ionization. Again, the onset of ionization starts violating the fundamental assumptions of compressible flow analysis.
At least back then, the consensus was that ionization energy was not recovered as flow acceleration in a conventional nozzle. Only the internal and pressure energies were recovered (together, those are the enthalpy).
The point is, beyond something like Mach 6, you start needing another design analysis model. Compressible flow is becoming increasingly inaccurate, and rather rapidly with speed increases beyond about Mach 6. That's not to say that ramjet won't work at higher speeds, but you have little way to model and predict it.
What you will notice as you look around is that there is very little in the way of design analyses that adequately model scramjet, other than CFD codes, whose input requires that you already have design drawings from which you can set up the analysis grids. The same sort of thing would be needed to model a Mach 7+ ramjet.
And even then, many crucial processes (such as physical chemistry) cannot really be included in a CFD code. Turbulence models seemed to be a fatal bugaboo in CFD codes when I last worked in the industry, but that seems to be resolved now. But without transient physical chemistry, you cannot model flameholding and ignition adequately. Which is why actual test is so often, and so vastly, different from what the computer predicted.
GW
From AIAA’s “Daily Launch” for Wednesday 6-26-2024:
About Starliner docked to ISS ---
THE WASHINGTON POST
Astronauts’ delayed return reflects high stakes for Boeing and NASA
Before Boeing’s first flight with humans on its Starliner spacecraft earlier this month, the company and NASA said repeatedly that a rigorous testing program following years of delays and costly setbacks meant it was finally ready to fly astronauts. Instead of coming home after about eight days, the spacecraft remains docked to the station, its return delayed indefinitely while teams continue to troubleshoot a series of problems in the capsule’s propulsion system.
About NASA’s new spacesuits ---
ARS TECHNICA
NASA’s commercial spacesuit program just hit a major snag
Two years ago NASA chose a pair of private companies to design and develop new spacesuits. Now, that plan appears to be in trouble, with one of the spacesuit providers—Collins Aerospace—expected to back out,
And ---
SPACE
ISS astronauts conduct 'spacewalk review' after spacesuit coolant leak
ISS astronauts are reviewing spacesuits and spacewalking procedures after a leak during a spacewalk on June 24. NASA's next spacewalk is still scheduled...
About Falcon-Heavy being successful yet again ---
SPACENEWS
Falcon Heavy launches GOES-U weather satellite
A SpaceX Falcon Heavy rocket lifted off June 25 carrying the final spacecraft in a series of geostationary weather satellites that also features several firsts. The rocket’s payload, the GOES-U weather satellite, successfully deployed from the Falcon Heavy’s second stage four and a half hours after liftoff, after the stage completed a sequence of three burns to place the satellite into a geostationary transfer orbit.
And, about the upcoming first launch of Ariane-6 ---
SPACE
Europe's new Ariane 6 rocket on track for long-awaited 1st launch on July 9
Following its wet-dress rehearsal on the launch pad in French Guiana, Europe's new Ariane 6 rocket is on schedule for its inaugural launch. The European Space Agency (ESA) announced during a June 25 press conference that the rehearsal was a "full success."
GW
Given the crappy valves they used in the NTO tankage and supply systems, I'm surprised it is rated for 45 days yet!
GW
The formula for plane change dV in the video is correct. It is also given in the orbits+ course materials. The estimate provided in the video is wrong, however, and way-underestimated.
The estimates for dV to change orbital altitudes in the video are incorrect, and underestimated. The correct procedures are in the orbits+ course materials.
The estimate for a deorbit burn in the video is incorrect, and an overestimate. The correct values and procedures to find it, are in the orbits+ course materials.
The estimates for the hypersonic airbreather space plane as a rescue vehicle are not just wrong, they are way, way, way wrong! Such will require nuclear propulsion to do that job as a single stage item.
It is possible to do it as a two-stage item, with chemical propulsion, but only with vertical launch. We have already been down that road here on the forums, and that argument continues, even today. But I stand by the results I have gotten!
Starliner is still badly flawed, but I am as yet unconvinced the two astronauts are doomed to death in it, if they try to return in it. I would recommend not certifying it for manned flights until the flaws are corrected (and they are numerous). But I really doubt NASA will do that.
Meanwhile, Boeing has pretty much gotten all the income-above-cost that they are likely to get out of Starliner. They know that. They are looking for a reason to cancel it, before it costs them more to correct the remaining numerous flaws, than the remaining flights to ISS are worth.
THAT ugly place is where we really are. It's not about lives, it's about money.
GW
Nice video Void, again. Thanks.
It was good to find out only the one flap had the entry heating damage. I'm just guessing it was the luck of the draw that the camera was looking at that one.
GW
Propellants with hard things embedded in it, historically did not prove to be very successful. As the composite structure deforms, the propellant-stiffener interface sees shear forces, and so the propellant then debonds from the stiffener. That not only weakens the composite structure, it also allows excess burning surface to be exposed to the flame as the surface burns back. That extra unintended burning surface results in a motor explosion, very nearly 100% of the time it occurs.
GW