47

I like the X-15, it was certainly an amazing airplane, but the truth is there were few benefits to the space program from the X-15. It was far from a critical or necessary step: The Mercury space suit was a direct derivative of the BF Goodrich Navy Mark IV, which had been in use for years. It wasn't developed for the X-15 The rockets used in the space ...


26

I'll complement GdD's answer from a slightly different perspective. In the history of aerospace engineering... Wait, there is a problem right there. Due to various historical reasons, there was no aerospace industry in the USSR, at least the way it is known in the West. The very word "aerospace" was almost never used before the 90s. Aeronautics and ...


22

The only way to get anything that far that quickly is to send it into space, and that's exactly what Musk is suggesting. The BFR will launch a passenger carrying spacecraft out of the atmosphere and into a sub-orbital path, it will re-enter the atmosphere close to its destination. Rockets launch pretty much straight up and a sonic boom would have to compete ...


11

No. Currently the altitude record for a jet is 37,650m (This is a zoom and climb record, not sustained flight). Ralph J sum up the issue pretty well, but let me add some data: Ramjets are the kind of engines that looks the closest to what you want to achieve. They top out at 2km/s Orbital speed would be 7km/s. And that's with a minimal payload. There is ...


10

I'm reasonably certain the speed limit (so to speak) on the SR-71 wasn't to prevent its skin from melting. The hottest the skin got during flight was less than 600 C. That's definitely hot--but it's a long ways short of the melting temperature of titanium (1668 C). Early supersonic aircraft often had control problems, because the leading edge of the air ...


10

Great question, but no, the X-15 was not a "critical and necessary step on the path to manned space flight" at all, it was used to test the feasibility of sustained and controlled hypersonic flight of an aircraft at very high altitudes and speeds. The X-15 was an extension of the X program, started in the 1940s, to continuously push the speed envelope of ...


9

The linear theory makes certain assumptions in its formulation: The flow is irrotational and isentropic. The perturbations are small; i.e. the bodies are small at small angles of attack. However, hypersonic flow violates these assumptions: For a body in hypersonic flow (blunt body with detached bow shock), an entropy gradient is developed that varies ...


8

This is the heat distribution during reentry for the Orion capsule: So the leading edge is hotter than the trailing edge, even for very large angles of attack (almost perpendicular). I assume a disk would have a similar heating profile. So spinning the disk would move the edge of the disk from a high-heating area to a less hot area. This suggests ...


8

No. Sonic booms are caused by shockwaves which form on the aircraft structure as it moves through the air, not by the engines. Completely unpowered craft can create sonic booms, for instance the Space Shuttle and other spacecraft on re-entry. Even if you accelerate the air along the airframe you aren't going to be able to stop the boom, because it's not ...


8

A converging shape at hypersonic speed in a low-pressure medium will produce close to vacuum pressure on its surfaces (hypersonic shielding). A small sideslip angle will only result in a very small pressure difference between both sides. Contrast this with a diverging shape which produces higher than ambient pressure on both sides. In hypersonic flow this ...


7

Business jets are developed to different rules than airliners. The biggest difference is that, indeed, fuel price and fuel efficiency are not an issue when what counts are bragging rights for the fastest plane on the ramp. Their speed has steadily increased and is now at Mach 0.935 for the fastest models. Compare that to Mach 0.78 to 0.85 for regular ...


7

A waverider will prevent the compressed air under the airframe from escaping sideways. An equivalent view is that the sideways component of the air displaced by the body is used for lift creation by straightening it and pushing it down at the wingtips. This allows it to fly at a lower angle of attack for the same lift, which reduces supersonic lift-related ...


6

TL;DR Probably not. Assuming we would have a very good mechanical solution/design we would still need a way to get rid of the heat, i.e. a heat-sink. Imagine the panel (or what ever we will call a part of the skin) is rotated away from the flow (into the inside of the vehicle), than we would need to cool it but where would we store the heat? We cannot ...


5

Scramjets There's only a couple flying examples. The early Soviet-born Kholod, the HyShot series, and the recent ISRO ATV all flew small scramjet engines, although none were designed for net thrust. By far the most [publicly] successful vehicles have been the X-43A and the X-51. Both were fully controllable, independent flight vehicles (rather than just ...


5

The idea of using small air holes to cool a surface is not completely 'out there'. In turbine engines, the turbine blades are cooled by blowing bleed air from a compressor stage over the blades. Here, cooling with bleed air makes sense, because the air in the turbine is hotter than the compressed bleed air, due to the added energy from fuel combustion. ...


5

I read that very high g forces could kill a pilot, brain pushing into the skull. High G-Forces cause blood flow to the brain to be impeded due to blood pooling low in the body under high acceleration. This causes the pilot to black out eventually. Is there a way of decreasing or surviving these forces and how would it work if you ignore aircraft ...


5

How long does the lithium take to evaporate and then to react with oxygen? Air in a scramjet is moving extremely fast (supersonic by definition!), so there is very little time left for mixing and combustion if you desire to create thrust from the the combustion heat energy. Your lithium engine will most likely trail a bright contrail of burning lithium but ...


4

Well, 2 G's is 2 G's, regardless of what speed you're flying. A level (coordinated) turn with 60 degrees of bank is 2 G's, regardless of your airspeed. What changes is your turn rate and turn radius; at 20 knots, a model plane at 60 degrees bank can probably complete a 360 degree turn in a few seconds and a radius of maybe 10 yards. At 300 knots and 60 ...


4

Pressure is the greatest just before the combustor in both jet and ramjet engines - therefore air would have against the pressure differential for this to happen (turbine only has therefore an indirect role)


4

Are you asking about current production or through out time? The SR-71 was powered by a Pratt & Whitney J-58 engine which operated as a partial ram jet at high speeds. At lower speeds it operated like a turbojet changing its internal shape as it increased its speed. The SR-71 was capable of departure under its own power from the ground. You can find ...


4

Technically yes, you could use hydrazine in a scramjet. But there's no reason to do so. The singular purpose of building a scramjet is to get air into the combustion chamber, so that you don't have to use a monopropellant, which all have high cost and poor energy density. Kerosene or H2 won't burn without air, so you need a scramjet or an oxygen tank to ...


3

René Lorin invented the ramjet in 1908, and his ideas were tried in flight for the first time from 1941 onwards. Different sizes were tried; below are two pictures, one of a Do-17 Z with a small Lorin engine (source) and below that one of a Do-217 with a much larger version (source). Speed increases of up to 150 km/h were recorded, but efficiency was poor. ...


3

I'm don't research hypersonic flight, but I bet the primary barriers of hypersonic flight are less technological and more political/economical. After all, we pay money and conduct research in order to solve technological problems. You would think that developing an engine is primarily a task for aerodynamicists since they can design better intakes, ...


3

Why Mach 10? Would Mach 3 or 4 not be enough? See here and here and here for the complications which arise at higher speeds. The linked article is full of misrepresentations - of course will the Busemann biplane create lift at sub-supersonic speed (what is that, anyway? I read it as subsonic speed). Give it a proper subsonic airfoil and it will do so just ...


3

Agility means that you can change the speed vector rapidly. The way this is done in aircraft is to point the wing's lift into the desired direction and then to increase lift as much as possible. The lift force over time results in a kinetic energy change which accelerates the aircraft in the new direction and decelerates the old speed away. Flying faster ...


3

Primarily the pressure differential between the stagnation pressure at the inlet and the ambient static pressure. Combustion takes place in an isobaric environment with the enthalpy of the exhaust gases being converted to kinetic energy by exiting the nozzle per Bernoulli’s Principle. Therefore the pressure differential between the combustion section and ...


3

You couldn't do it to control reentry, but you certainly could do it for a vertical landing system that might be a bit less technically demanding than a rocket that can descend under control with its engine running as SpaceX does. You are limited by the mach# of the tips of the rotor, which have to be subsonic while spinning. You would want a rotor that ...


3

There were three competing ways to space pursued in the US while in the USSR everything was centrally managed, so they followed only the way that Konstantin Tsiolkovsky had first proposed. What were those three ways? The US Navy used a home-grown team to develop a rocket at the Naval Research Laboratory. Their Vanguard rocket failed several times, however, ...


2

True Air Speed limit is Mach 1. Ground speed is not relevant to this question. The reason there are currently no flying supersonic business aircraft is that designing and building an aircraft capable of supersonic flight is very expensive and technically challenging.


2

This has long been a desire of the aviation community; in fact, at the beginning of the space race the Air Force side tried to get to space using planes. That led to scores of studies on reentry vehicles and culminated in the X-15 program. On the other side were the Army guys who got substantial help from other Army guys (on both sides of the Iron curtain). ...


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