monophonic

All it comes down to is the non-delivery clauses in the commercial crew contract. Boeing will go whichever way costs less, whether that is pushing through with the currently contracted launches, or canceling Starliner and paying whatever fines they must. Now I do not know what sort of penalty clauses the contract includes, so it very well may be the cheaper option to break it. Even free, knowing how some governement contracts in my country are...

ASRAAM, AIM-9X and probably Python use imaging infrared seeker heads. At least Python is purported to be capable of choosing which part of the target aircraft to attack. I presume such functionality would use pre-AI image recognition technology. This is, as mentioned above by a few posters, a short range technology. However some anti-aircraft missiles do now combine radar and infrared seekers into a dual method solution. These include RIM-66M Standard Missile 2 Block IIIB, and Stunner missile of Israel's David's Sling system. However, at least AIM-9X has been proven to still be at least somewhat vulnerable to simple flare countermeasures ( https://en.wikipedia.org/wiki/Ja'Din_shootdown_incident ). Below is a QF-4 target drone as seen by ASRAAM seeker. Image sourced from a post at f-16.net ( https://www.f-16.net/forum/viewtopic.php?f=18&t=7883&start=18 ).

Thanks! That sounds like a kerbal design all right. I did go through all the links, but all I saw was the black image. I have no account of any kind though, so might not need to be verified to see.

Well, they could use Vulcan for the cargo Starliner (Starhauler?) launches. Of course that would require work to integrate the capsule with the launcher, but not needing to crew rate all that should help some. Also, unless Boeing has already decided to cancel Starliner after current contract, that work is in the engineering roadmap anyway. Whether that can be done in time for launches in 2025 is another question though...

I'm not sure I follow your vectors correctly here. As I understand this, the advancing blade generates more lift while the receding blade generates less. This tries to tilt the rotor sideways, not back to vertical. This effect increases with the airspeed. A helicopter compensates with the cyclic so the receding blade has a higher angle of attack than the advancing blade. A multirotor does not have cyclic control. Are you trying to imply that in a two rotor situation the drone would settle to a drift perpendicular to the line between the working rotors? Also, are you sure the restoring torque you mean will try to restore the rotor axis back to vertical in the world sense and not perpendicular to line of movement? Because the latter is unlikely to be exactly horizontal, and likely to deviate even more from horizontal as the small imbalances cause disturbances. Even a small downward pitch will lead to a crash unless corrected by active measures, and a small upward pitch will lead to a large downward pitch when dropping air density leads to a rotor stall. There is a reason full size helicopters are not considered stable even in a perfect weather. A small multicopter is a lot more susceptible to the atmospheric disturbations, that will disturb even a full size helicopter to a crash, if not actively stabilized by pilot or electronic controls. Also, I realised it isn't possible to arrange the (quad) rotors so in a two rotor situation the remaining rotors would spin the opposite ways. Doing that would couple torque control with rotation about a horizontal axis, which is not conductive to a stable flight. So we end back to needing a minimum of four (fixed) rotors to stay aloft.

Two out of four leaves no control over rotation around the line between the two working rotors. May be survivable in a high school textbook (ignore all other physics) scenario, but you don't need much imbalance in weight or air resistance of the two dead rotor arms, or turbulence in the air to get the airframe rolling uncontrollably. Yes, someone needs to mention the CH-47. Those have control over the rotor to rotor line by varying the blade angles on either side of said line. Cyclic control could make two engine situations survivable, however the cost and complexity would be exorbitant. Technically doable, though. RC helicopters existed already in the 80s, probably earlier. Even if the rotor could run in reverse, you would lose all torque control in that situation and start rotating wildy around the vertical axis. Another unsurvivable scenario right there. You simply need at least four and an even number of fixed rotors working to have control of the flight attitude. You can replace one rotor by adding tilting on another, but the total number of moving mechanisms stays the same. Plus you complicate the math, add to the count of different parts required and one rotor needs to be connected via a moving joint. All things conspire to make four rotors the optimal number.

Those engineers have access to a myriad of chips that take full advantage of the benefit of Earth's magnetic field protecting them from the radiation of space. Exposing them to deep space conditions would quickly turn them from "network chips" to "random number generators with extra steps." When you combine the requirements of radiation hardening and certified for space, you are left with a very short list of potential chips. It is very possible that only one chip can provide those and the required network performance. Now, replacing failed chips is one thing. It is a lot harder problem, if said defect is in the design of the chip. In that case replacing chips does nothing. There are only two ways around that. You could use a different chip, assuming one is available. That will require re-designing, manufacturing all the surrounding electronics, which takes time and money. Or you can try and work around the defect in software, to prevent the defect from triggering. That also takes time and money. Even if it is individual chips failing and not a design defect, there must be time and money spent to understand why they failed and if that could happen again during the operational lifetime of the station. So, no way out of this that does not require time and money.

But most importantly you can not certify a vehicle that has uncertified software. I bet a lot of components in DreamChaser already have their certifications, and any changes requiring re-certifying would be expensive...

I feel the issue of adding catenary has been exaggerated there. Many lines in the New England area used to have one as well. What exact infrastructure are you thinking of? This side of the pond the railbed is often lowered by a couple of feet to get the needed extra height in a tunnel or under a bridge. Through trusses can be a little more difficult, we have a few where the top cross members have been replaced with upward arcing parts to make room. A bigger issue I see is the extremely tall pantographs needed to reach a catenary that fits US style double stackers and autoracks underneath. The rectifier thing is a non-issue. Most currently in production electric locomotives use a DC intermediate circuit anyway, thus have such a rectifier circuit. It is an off the shelf part. Also battery-electric trains are now available from multiple manufacturers (Siemens, Alstom at least) and starting to enter service in Germany. They are mostly replacing diesel units on unelectrified rural lines though, charging in the cities where catenary power is available. Torque balancing with an odd number of rotors is a complex issue even in a drone. You need the ability to tilt at least one rotor, extra anti-torque rotor like on a single rotor helicopter, or very precise tilt and RPM equalization like on the Cierva. Meanwhile even number of rotors makes it trivial, as you can rotate equal numbers of rotors in opposite directions and adjust with minor changes to RPMs. I see no advantages in having three rotors over four. The driving force on tunnel sizes in high speed rail is the impact from the pressure spike caused by the train entering the tunnel at high speed. Removing the catenary will not allow reducing the size of the tunnels. Only limiting speed in tunnels would, but that would negate the advantages of building high speed rail in the first place. The arc caused by the air gap would eat at the wire and pantograph like no tomorrow. This is already an issue with traditional wire and carbon brush panto in freezing conditions. Newest locomotives here have an option to have the forward pantograph disconnected but up just to brush ice off the wire so the connected rear pantograph can make better contact with the wire. The need to prematurely replace wire due to pitting from arcing is just that expensive. The electric company won't provide the power lost in the arc for free, either. I once traveled in the first car behind an earlier generation electric locomotive in a cold winter night. The light from arcing lit up the terrain by the track well enough you could have read a book there, and it was an almost constant light. There was a lot of energy lost as light that night.

Fully buried in constantly wet terrain is no problem. The multitude of swamp mummies discovered attests to the ability of matter to stay together in a low oxygen environment. For railroad sleepers the problem is that they are by necessity exposed to air from above, and thus get wet and dry out repeatedly as weather, well, weathers. If that wood can handle that for a century, I'm amazed! Regular creosoted wood ties last about thirty years, I think. Future is in concrete or new materials though. As amazing as wood is, modern management methods make the consistent predictability of those a very valuable property. Trees are always individuals and sleepers made from any wood have much higher variability on durability and dynamic behaviour under load.

Wooden railway sleepers is the only remaining allowed use for creosote in the EU. It is in general forbidden due to the carsinogenicity, but no-one has been able to devise a treatment that makes wood survive even half as long buried in ground, thus creosote is still allowed in sleepers. Wood and concrete sleepers have somewhat different properties making replacement of one with the other not a straightforward process, unless you can accept a severe downgrade in allowable travel speeds. The crushed stone ballast used with concrete sleepers breaks down over time, as passing trains causes movements that grinds the individual rocks against each other. Natural erosion processes also occur, even cracking stones in halves. Thus the ballast needs to be renewed or replaced periodically. Renewing includes filtering out undersize stones and adding fresh ballast to balance the lost amount. Some filtering machines use rubber beaters rotating at high speeds. Sufficiently large stones get thrown a small distance by the beaters while too small, lighter stones fly farther and are discarded beside the railbed. They should be caught and funneled down though, as big-ish rocks flying at high speeds in open areas are a safety risk.

No KSP being marketed, no incentive for the publisher to pay to keep the forum online.

I'm pretty sure the units I've owned all worked with bang-bang magnetron power control. Mind you majority of them have been visually identical other than the front panel, so probably all came from the same factory in china. The "PWM" frequency appears to be on the order of 0.1Hz or so, judging by the cyclical changes in the hum and how melting of butter in the first few seconds is not affected by the power setting. The spinner does not stop though so it must be powered separately from the magnetron. Never took one apart though, and ain't gonna touch the current unit as it still works.

So when an accident renders your top performing crew member a quadriplegic, out the airlock he goes? Where do you draw the line between a deadbeat and someone worthy of sustenance due to their prior performance? Who gets to draw that line? Does the rest of the crew just take it and wait for their turn to slip below that line?