RCgothic

It looks like two deck extensions have been retracted over the centre in order to narrow the barge down for transit.

More legs is heavier, so that's an arbitrary assessment of "better". Five legs is the minimum that can tolerate one failure on a reasonably flat surface.

Apr pressure tends to straighten out joints. To counteract that you could have mechanically assisted joints.

What you've just written is exactly equivalent to "the electromagnet stops working when the truck runs out of battery." In order to generate motion, you must transfer momentum to an expelled fuel. If you recapture the fuel, it is not expelled. The sum of momentum of the craft has not changed. If you want to preserve your propellant for the life of the nuclear fuel you can use it more sparingly, which will result in it being hotter and faster and carrying more energy away per kg, but that requires the engine and reactor to operate at higher temperatures. Rocket engines work on the principal of conservation of momentum. (DryMass+FuelMass) * InitialVelocity = DryMass*NewVelocity + FuelMass*FinalExhaustVelocity Bear in mind that velocities are vectors and opposite vectors have opposite signs. If you recapture the exhaust, doesn't matter how, then FinalExhaustVelocity = NewVelocity = Initial Velocity. No exceptions.

You are willfully considering the forces on only a portion of the vehicle and not the sum of all forces.

So just to point out that the US withdrew from the IRNF treaty this week in protest about "new kinds of Russian cruise missile". And I remember another news bulletin earlier in the year about potential Russian hypersonic nuclear power cruise missiles with unlimited range. Could be one of them that let go in testing?

Point of interest, Falcon 9 requires just six more successful flights to equal Soyuz at 97.4%.

I think the precept of this thread basically misunderstands what's happening in a fission reaction. In a Fission reaction atomic nuclei and their protons and neutrons are arranged into a more stable configuration. Iron is the most stable configuration. That's why Fusion, joining small nuclei together, and Fission splitting large atoms apart, both release energy. To go the opposition directions consumes energy. That's why stars tend to die when they try to fuse iron, and the heavier elements are only really formed in hugely energetic events like supernova. What do I mean by a "stable configuration"? I mean a state that takes a lot of energy to disturb. The harder it is to disturb, the more stable. An atomic particle in free space has a lot of energy. It can't just join another particle and hold onto that energy - that amount of energy is by definition enough to disturb it from the stable state, but the particles want to be stable so the energy has got to go. That "binding" energy gets released. Particles generally aren't in free space. But if you compare their starting and end states you can work out how much energy will be released by the net difference in the stability of the two states. This is exactly the same theory as chemical reactions. The difference is that nuclear binding energy is comparatively vast, and vast quantities of energy have non-negligible mass of their own. It may appear like fission has reduced the mass of the atomic particles, but actually they've only given up the mass associated with their binding energy. Once you've reached iron, there is no more binding energy to give. You can't "hyperfission" to get more. Furthermore, many elements either side of iron are nearly stable. It takes a lot of energy to disturb them into iron and the net return isn't great. Then consider that generating the required energy isn't 100% efficient and you get a prospect that isn't worth attempting. That's why we only attempt to split very unstable nuclei like Uranium.

The reason that accelerated flow exhibits a lower pressure is that a greater proportion of the air molecules are moving in the same direction. In highly simplified form, if all the air molecules are moving parallel to a surface, they are not colliding with that surface so zero pressure. Bernoulli is just Newton for air. Obviously it's more complicated than that because fluid flows do not behave simply.

Consider flat disc moving at some arbitrarily stupidly large velocity, presenting its flat side to the airflow. On the reverse side, every air molecule will be removed from its path. Effectively a vacuum. The limiting low pressure is -1atm gauge at standard temperature and pressure, or 0atm absolute. You can't get an air pressure lower than zero. On the other side the plate is colliding with vast quantities of air molecules. The faster the plate goes, the more collisions, pretty much without limit. The high pressure upstream can therefore be arbitrarily high. So there is no limit to the potential pressure differential across the plate, as determined by velocity. Now angle the plate into the airflow. Now the pressure difference is at an angle to the airflow. Congratulations, you've now got an arbitrarily high lift component. Everything else about aerofoil design is about chasing efficiency or operating window.

Newton's laws always apply. In equilibrium, the force of gravity is balanced by lift pushing on the wings. The wings push equally on the air. (3rd law). A mass (in this case of air) experiencing a force is accelerated (2nd law). The air is pushed down.

A tug doesn't necessarily have to be a pusher.

Launch Escape System. Usually a solid rocket attached above the capsule.

Docking's a solved problem. Being bigger doesn't make it harder. Potentially it makes it easier as more minute corrections are possible.

There is zero requirement for a man-rated superheavy launcher. You don't need a superheavy to put a crew in orbit, and you don't need to man-rate a cargo superheavy and make everything five times more expensive than it needs to be. RS-25 only had to be uprated because of the poor launcher architecture. Does Raptor need to withstand the heat and vibration of solid boosters? No, it doesn't. Because raptor will only fly on competently designed vehicles.

So the engines alone for SLS cost as much as five or six band new falcon heavys. Insane.

For the starlink constellation it might be that you don't need a hot spare. Because you have so many sats in the same plane, you just space out the survivors and absorb a slight reduction in signal strength.

My brother and his family just moved from the UK to Australia. There's a good chance I'd be willing to pay to turn days of travel into 20 minutes even at a one in a thousand failure (instant death) rate.

If a flight is only 20 minutes and it involves anything close to a full g or greater, there won't be any bathrooms. In the first instance, the trip isn't long enough for them to be necessary and in the second it won't be safe for people to move about the cabin.

Nearly, I was watching on a minute delay. Actually had more of a heart in throat moment for the side booster entry burn. The centre core was disappointing, but we knew that was a dicey prospect going in.

Could be throttle valve controller. Failure to throttle down might trigger a last moment abort.

Yeah, propellors and wings are both aerofoils. They both create thrust by deflecting quantities of air by Newton's third law. An understanding of Bernoulli just allows you to design shapes that do so efficiently. There's no special distinction for propellors or turbine blades. They just have twist and chord variation to compensate for the varying effective velocity vector of the incident airflow over the aerofoil due to the circumferential speed of the blade varying from the root to the tip.

You learn more from your failures. At least this was a non-mission-critical failure. The side cores did look very much like a RUD. I think it was the infra-red camera getting super-saturated by the exhaust gases, causing the landing burn to look more spectacular than usual!

Ionising radiation only comes in three types.

Or don't turn it off and just hover. If the device uses less energy to run than it would take to accelerate to orbital velocities, you just wouldn't. And if it does use more energy than it takes to get to orbital speed, might not be worth having it at all. The ascent is a relatively small part of the energy requirement for accelerating to orbital speed.