wumpus

Makes a lot more sense than Jessica Dubroff. https://en.wikipedia.org/wiki/Jessica_Dubroff I have to point out that I like to compare putting a kid in a barnstorming flight to the idea of a kid to the ISS. I'd imagine that parents might regret not letting their kids go in such a flight (I think a few astronauts were inspired by such flights), but the danger is likely the same (granted, the danger for everything else is so much lower that modern safety precautions likely make sense).

Yikes. Just how often is central Texas under a burn ban, or does Texas simply not dare violate a property owner's right to create wildfires? Maybe the brush is thin enough that those roads are enough of a firebreak, but I suspect that central Texas wind can move sparks a good long way. Maybe the Californians running spacex know a lot more about wildfires than me (I'm on the East Coast, they're unheard of here) and understand why it isn't a problem (or at least wasn't when the fire in the picture happened).

At least one of Japan's small rockets designed for orbit (not sure if it succeeded) didn't have a proper guidance system and simply was angled and rode the gravity turn to orbit. This was presumably due to Japanese hostility to nuclear weapons extending to potential ICBMs. There are plenty of parts of 1950s state of the art that are hard to duplicate. I can't believe that guidance systems are one of them.

For takeoff, I'd assume that such a spacecraft could be launched off a rail. This is a "build *lots* of infrastructure to make *many* launches cheaper" strategy. I can't see the rail approaching the cost of the lasers/power supplies for same.

At the time (i.e. well before the movie. I know I've heard more of it directly from real (small plane) pilots than people who saw the movie), my memory is that the air traffic controllers were surprised that Scully picked the Hudson as his place to land (they assumed an airport even if their screens didn't indicate sufficient velocity or altitude). Obviously you should never look to movies (especially the Hollywood variety) for facts. How many fully autonomous UAVs are made with the budget and requirements of an Airbus autopilot? If we get sufficiently large UAVs flying over populated areas (the UAV company I worked for moved from Washington DC to Texas for a reason. Much easier to pay a rancher for a cow collision than deal with landing on a school) we may see such software. Ask the good folks at the University of WV and others who discovered less than ethical software in VW diesel controls. An autopilot does what it is programmed to do, and certainly doesn't value its life if the plane manufacturers (or whoever sources the autopilot) want it to look like it is saving money.

That number is almost certainly 32 bit (or rounded to 32 bits in an important place somewhere). This is where the kraken steps in: your spaceship resides in the center of a 32 bit reference system bubble defined relative to a 32 bit reference system defined by Kerbol. These were sufficient to slay the kraken for any standard use of KSP, but really pushing the boundaries might raise the kraken. The whole kludge is due to Unity using only 32 bit floats. It was built to be for highly portable games (don't try doubles on phones, old [non-x86] consoles, or GPUs) and not scientific calculations (which nearly always use 64 bit doubles). https://www.youtube.com/watch?v=TSaNhyzfNFk (Scott Manley explains 64 bit in KSP and Star Citizen. Note he's not a hardware guy so I don't think this is *quite* right, but it is close enough down to roughly the assembler level).

I went and read the blog, and was really wondering on the suggested "amature" method of booster construction. While I'd agree that it is quite likely that you could manufacture carbon tubes at reasonable cost, this still leaves the issue with filling them with ammonium perchlorate (and similar high-Isp cores). The (currently pinned) amature rocket to orbit thread considered "off the shelf" ammonium perchlorate boosters (for the last stage) and possibly homemade "candy rockets" (to get the first stage going), but I don't think anybody considered whipping up their own ammonium perchlorate and filling a homemade tube: that type of thing should be done with sufficient automation to be done without human involvement and with certainty that an "all clear" whistle can be blown to allow the humans to enter. This type of thing is possible in an ongoing commercial environment, but I have my doubts about amature builders.

Interesting, that's the first I've seen official information on booster separation velocity (although you can slow-mo through the video and get the data in km/h). Expect much scarier velocities on Falcon Heavy (success of the mission wouldn't be nearly the surprise that spacex is warning people of, landing the center stage is far beyond any landing they've pulled off (because the upper stage needs so much more of a push, and the center stage is the only thing that can push it).

Air would make a lot of sense and easily hit any "magic Isp number" (although I think it also means that you wouldn't get 800 above the atmosphere, there were a few catches in delivering that number too far away from the laser. But getting mach 6 roughly drops the "magic Isp" number in half (and I think Isp bottomed out around ~600, in theory). I also don't think laser "complexity" was so much the issue as that lasers with the needed power simply don't exist (or only deliver said power for milliseconds). Somebody might try this once the Navy has fielded tested laser weapons, but I suspect that such small startups can't develop powerful continuous lasers out of burst ones.

The famous counter argument would be Flight 401, a plane that crashed because the entire flight crew was trying to diagnose a burned out light bulb. http://articles.sun-sentinel.com/1992-12-29/news/9203090325_1_landing-gear-jumbo-jet-plane Not to mention the presumed deliberate crash of Germanwings Flight 9525 in 2015. MH370 (Malaysian plane that completely disappeared over the Indian Ocean) was worth several billion dollars in parts. The exact reason it disappeared is likely to never be known, but piracy is certainly a possibility (it worked for BJ Cooper). Presumably it would be easier to subvert a programmer than a pilot/flight crew (since it would be easier to kill the pilot when he landed). I'm guessing that terrorist attacks/hacking are a better justification. To commandeer a plane with a pilot, a terrorist has to force his way into the cockpit (and all passengers can fight him off). To commandeer a pilotless aircraft, a hacker needs to find an exploit in the control software and fly the plane into the ground/buildings/whatever. To a certain extent, this is already true of Airbus planes, and the also attempt to avoid crashing due to pilot error. Early data shows that the Boeing system (trust the pilots) is better, but I suspect in the long run the Airbus software will remove bugs from their software (human error will always be with us). Note that the FAA (and presumably similar agencies worldwide) actually has standards for software. You can't put a windows machine in charge of your aircraft: *every* line of code needs a justification for its existence (don't expect this to be true for automobile "autopilots"). Terrorist hackers are much more likely to find easier targets elsewhere (such as automobile/truck "autopilots"). One final thing: if you want to argue humans would do better in "Sully" like situations, it might be better to hand over the controls to a "harbor pilot" on the ground [and use encrypted radio controls] with "impossible" amounts of takeoff/landing experience (for that airport) relative to normal pilots (much the way that harbor pilots have the advantage over normal captains in their harbor). Assuming they would be physically located at "their" airports, latency wouldn't be an issue.

April 8, 2024. Mexico City is dead center of an eclipse (this might make travel more expensive, but still...). This might require some kind of KSP 2.0 (or more than just one DLC) to keep Squad sufficiently active in KSP to have a KerbalKon, but it really makes a one time and place for KSP types to show up.

If the badS flag isn't set, you will have to set if manually.

NASA's X-43 data (the fastest airbreather so far) hits net thrust~=0 at mach 10. At mach 7, net thrust should be higher than error (but apparently actual data is classified) but remember the catches in the X-43: It is a tiny little aircraft launched by a giant SRB (in pictures it is that tiny shiny blob on top the SRB). It is optimized for a single speed. It only carries about 10 seconds of fuel and no "higher stage". The drag and mass of all that could easily drag mach 7 flight down to zero The actual acceleration is completely obscured (just "more than error") and axises are unlabeled. https://hapb-www.larc.nasa.gov/Public/Documents/AIAA-2006-1-317.pdf Depending on the leftover fraction of delta-v needed, you might end up needing three stages. Expect the economics of this to ruin any benefit of using airbreathers (exception: recovering two stages out of three stages could easily have advantages over recovery one or two out of two).

As KSK mentioned, nothing in rocket science is ever simple. Second, there already exists a Merlin to work in the atmosphere. They are on stage 1. You really can't afford to use one for stage 2 power. If you meant Draco engines, that is possible if painful. The catch is that adding dry mass to stage 2 is wildly more painful than in stage 1. Instead of a heatshield you might do a more powerful backboost. This should be effective as the payload is missing and your delta-v should be much higher. Note that light heatshields are ablative and limited use, something that Spacex historically shys away from (although they may think it worthwhile like the landing legs/crush zones). Last I heard, the plan involved a relatively high glide ratio to kill most of the velocity, but actual landing methods weren't released (note that stage 1 is not a place you want heavy parachutes, and I'm not sure that extra draco engines are any lighter). Stage 2 recovery has always seemed like a wild dream. Most of the reason Falcon 9 appears to be more reusable that the Space Shuttle is that 90% of the thing doesn't go past Mach 6 or so (at least the ones to be recovered don't), so the booster has far less wear and tear. The upper stage will suffer all the damage the Shuttle orbiter did, has to kill all the velocity somehow on the way down, all to recover the final 10% of the spacecraft. Spacex probably expects this to be more like Falcon 1 recovery plans: try to test the first idea for ITS before it goes into final design. Failure is likely expected and only means more data for the next design (this might mean that there is no "final landing" system like parachutes or landing engines: they just want to see a good terminal velocity near Earth's surface. Everything else just uses up the customer's payload capacity). One quick and dirty means of making stage 2 recovery easier would be to add a third stage. Since the dragon capsule already has draco thrusters, the idea would be that adding an expendable drop tank to dragon would allow stage 2 to max out at a lower velocity and have an easier recovery. The biggest issue is is that even with zero-mass fuel tanks (I suspect they are vacuum fed, which might throw off the calculations at even this lousy wet/dry ratio), the difference between CRS mass and maximum mass to LEO with recovery nets about ~2km/s with draco's Isp of 300. While this would presumably mean considerably less fuel in stage 2 (and could presumably trade a bit more), it isn't clear if this is enough to make a difference in recovery. Oh, and expect a lot of paperwork when increasing your hazardous materials (dracos use hypergolics) by a factor of 3-4.

Are the boosters that use three engines useable? Those burns cut the landing time by a lot (I don't think a single engine can get a TWR>2, so gravity losses add up). Not sure if they need fuel in separate tanks for side engine cutoff or simply use the main tank (obviously they need some reserves to avoid fuel-out, landing with separate fuel reserves would hurt dry mass).

Probably the biggest reason that asparagus staging is no longer popular (or at least why I don't use it, SSTO craft are another favorite alternative) is that it is generally cheaper and more efficient to simply grab a larger part. In reality, it costs huge amounts of money to design a new rocket or even a larger fuel tank. Of course, building something like a Falcon Heavy or Delta Heavy out of their "base" rockets is also wildly more expensive than you would think (it sounds like Musk was shocked at the time and effort), but still cheaper than custom designing new engines, fuel tanks and custom plumbing. In KSP "asparagus staging" pretty much came to mean horizontal staging of identical engine/fuel tank combos, all dropped in pairs. This was pretty much due to both the original aero model (as noted above, it didn't care if things were horizontal or properly vertically occluded) and the souposphere. A TWR of 2.0 was ideal for the souposphere during the entire ascent, so identical stages were almost universally employed. After looking deeper into it, I was pretty sure a "nautilus staging" with exponentially decreasing masses (more fuel even with the same engines, but changing engines too) would be better far better in terms of delta-v (although possibly not for Kerbin's old souposphere or even current Eve (which is where you would want these tricks anyway). There are still many lessons you can learn from cross-feeding stages in KSP that don't employ traditional asparagus. Drop tanks are typically a great idea (empty fuel tanks in KSP are far heavier than in real life, mostly to compensate for Kerbin's lower orbital velocity) even if they don't have engines on them. A favorite trick of mine is to put a drop tank above the payload and pump that tank empty and stage it (in at least vacuum, you don't want to hit it). I'll admit that the cost and mass of a terrier engine makes that less needed.

If you want to experiment with TWR balances, expect to spend a lot of time adjusting mechjeb to create repeatable (or ideally optimal for that TWR) flight paths. You can get wildly wrong data by simply firing sounding rockets vertically into the sky (I think those work best ~2.0 TWR for a single stage. This didn't help me for getting to orbit).

They were launched over a 20 year period (a long time for a satellite to do nothing). And I'm not sure that cheap rockets existed between 1990-2010 (Pegasus probably *was* the cheap solution). And while it certainly requires a lot of military ties to use surplus missiles, it is pretty odd thinking of something that "beats swords into ploughshares" by using surplus ICBM stages to launch satellites as a "military program". The satellites seem to be a mix of military, NASA-science, and commercial birds. I suspect that the "ATK" bit of the company (I think bullets are their main product, although with big companies it is hard to tell) has a larger portion of sales to military.

Is this an issue of "you need the right background", or a matter of "even with a team of experienced engineers it still takes extended amounts of time and lots of prototypes and expensive lab equipment?" A lot of the controls issues (even for things like trying to build something like Rocket Lab's electric turbopump motor) isn't out of reach of many electrical engineers. Building any circuit board tends to add a million dollars to the cost of the project (although typically such boards are larger than anyone wants to use in amature rocketry), but that has more to do with engineer-hours and costs (note that it should be pretty easy to get an engineer to build a one-off. About 90%+ of the time is spent for reasons that are really only necessary for corporations and can be ignored for this type of project). Any project like this is going to need some pretty specific backgrounds. Of course, if you were starting from scratch (instead of starting with a KSP forum plan) you would presumably plan your rocket around your team's skills. So the idea is to require only reasonably common skills (or at least common among those willing to spend the time needed to get a rocket into space. That likely includes more people with turbine knowledge).

If you really want to do an ideal landing, I would recommend Minmus. First it is far more forgiving (less gravity), second you can really do a perfect horizontal burn in the flats (add wheels perpendicular to your engines) and then land on the wheels. Trying to land on Mun (especially without being able to pick your landing zone) with extreme horizontal velocity means crashing into a ridge or similar. If landing a spaceplane that can land backwards, it might help to put an octo probe at the rear and press "control from here", this will allow all RCS input to be properly reversed. As noted above, on all surfaces this is extremely dangerous for little savings (while it might be less dangerous on Minmus, the delta-v saved is tiny).

I remember a Scott Manley video (collaboration station, if I recall) when Scott mentions he is launching during an eclipse. I thought that was pretty cool, but rare enough not to care about. Then I looked at today's xkcd comic and realized that for stock KSP (where *everything* is on the elliptic, and KSC is on the Equator), eclipses should happen at KSC every month. Anybody seen an eclipse at KSC? Is my physics wrong? Does anybody make a point at launching during an eclipse?

The Pegasus rocket was created and is run by Orbital Sciences Corp (now Orbital-ATK) and I think was the dawn of commercial satellite launches (back in 1990). While they started with the B-52, Orbital now owns a L-1011 (bought in 1994) for launches. It isn't exactly a popular launch system anymore, with 3 launches since 2008 and one scheduled for November. However, with 43 launches (3 failures), it was more than enough to get Orbital in the space business. A follow up (minotaur-C) replaces the air-launch with a surplus ICBM (Peacekeeper/MX) and provides three times the payload (but also has 3 failures in far fewer (6) launches). Pegasus (at least the rockets, but without the wings) seems to be largely flown on top of surplus ICBMs and similar early stages (see Antares with NX-1 rockets).

There was a small startup called Escape Dynamics which made an effort to develop a SSTO with an Isp of ~800s. The "engine" would consist of ground based lasers (or masers) that would heat up the reaction mass tank (full of hydrogen) and launch that way. The power output from the lasers doesn't really seem to be something Escape Dynamics seriously attempted to provide, but it is an ongoing military research program by the US Navy. While it is only concerned with power during pulses (which is a great way to destroy missiles), it is also the most likely means of providing the power needed to launch a heat-powered rocket such as Escape Dynamics proposed. No idea if 800s is enough for SSTO to be viable, although reducing dry weight enough to change a log by 80% is heroic. Perhaps once the lasers get it going supersonic, it could use Ramjets/SCRAMJETS to assist to mach 3-7. In any event, you need an unbelievable number of flights to justify such a contraption over reassembling conventional rockets (and don't expect to be saving much fuel, if any). I doubt that missing any "magic Isp number" was what did in Escape Dynamics, lack of available lasers was much more likely. Another possibility (based on a test vehicle that has already flown) would be based on the X-43. This would greatly resemble any effort using the SABRE, although it might extend the staging velocity a bit. I should be noted that the paper that the NASA investigators published didn't include any measurements of thrust/acceleration. Acceleration was clearly positive (although not labeled) at mach 7 (faster than SABRE) and roughly similar to the negative acceleration due to drag (so presumably pretty good). Acceleration was only "most likely positive, statistically speaking" at mach 10 and clearly not useful for accelerating a spacecraft (although more research might allow sustained mach 10 flight). I've mentioned another paper before (likely by students digging through NASA data) which included Isp measurements, but couldn't find it today. Isp is projected to be 2900s at mach 6, measured Isp was not included (although I'm pretty sure it was over 2000 for mach 7). https://hapb-www.larc.nasa.gov/Public/Documents/AIAA-2006-1-317.pdf Note that I think Spacex can a put commercial payload into orbit for less than the projected "government accounting" price listed for the proposed scramjet rocket, with the possible exception of the final SSTO (no speed listed for switch to supplying oxidizer). I have no doubt that Spacex can break the $1000/lb mark first (note that any marketing saying as much is quoting prices for "with recovery of first stage" and payload mass "without recovery"). Don't be too surprised if Blue Origin beats Spacex to it (if and only if you have a truly massive payload).

Way back when I was young (and the Apollo program was fresh in people's minds, if already canceled), there was a made-for-TV movie called "stowaway to the Moon". A kid sneaks on board a Saturn V and proceeds to make it to the Moon (no idea how they convinced anyone that you could hide in a space capsule). I doubt there was any more realism involved. Another space-kid-stowaway was shown in "The Twilight Zone" (1980s edition, probably a reaction to "Space Camp" above). Things didn't go as well for anyone onboard, especially the kid. It was called "the Cold Equations".

The following is something I posted a couple of years ago (presumably after reading the book and getting an idea of the timescale of how long rocket science theory has been understood and how tricky it is to put into practice). While the name "asparagus staging" apparently barely predates KSP, the idea has been around a long time: And obviously it is harder than it looks like in KSP. The book I am quoting is from 1958 (presumably hastily published after the Sputnik launch). It is a nifty book I found in my parents old collection: being from 1958 it starts *everything* from first principles, without launching into extremely specialized engineering. I've looked through some fairly well stocked used bookstores for other Kerbal-type books on rocket science, but haven't seen anything close. http://www.amazon.com/Space-Flight-Early-thoughts-projections/dp/B0000CK2Z4/ref=sr_1_1?ie=UTF8&qid=1451578393&sr=8-1&keywords=space+flight+by+carsbie+adams