Questions tagged [hypersonic]

Questions about flight at hypersonic speeds, typically defined as above Mach 5.

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Are shockwaves responsible for heating in very sparse atmospheres?

I recall learning about hypersonic flow in high atmosphere. I think one of the modelling assumptions used is that the relative air flow is so fast, and the average space between molecules is so great, ...
1 vote
91 views

What limits the speed of a hypersonic aircraft flying in the lower atmosphere? Are there estimates for its max possible speed?

I'm guessing it is the heat resistance of the missiles leading edge material. Hypersonic cruise missiles all seem to attain Mach 6 and below. The boost-glide weapons fly faster but up much higher. I ...
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Hypersonic Boost Glide Range

Looking at an article earlier about hypersonic boost glide vehicles and I noticed how small their L/D ratios were ~2.5/1. If they begin their hypersonic glide at 50km in altitude would they not ...
41 views

Formula for comparing drag on planes flying at different speeds at different altitudes. Ex: Mach .80 at 40,000 ft, vs Mach 5 at 100,000 ft

I am interested in getting a sense of how much extra energy is needed to overcome drag at different speeds and altitudes. For example, for me a baseline would the drag on an airplane flying something ...
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1 vote
161 views

Does lift-to-drag ratio asymptote to 4 (or 6) at high Mach numbers?

The Kuchemann equations for L/D at high mach numbers, approximately verified by wind tunnel tests, were: $$\left(\frac{L}{D}\right)_{max} = \frac{4\cdot(M+3)}{M}$$ and, for wave riders \left(\frac{L}...
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1 vote
126 views

How do the shockwaves (supersonic and hypersonic) interact with the structure?

My main question is why spaceplanes are conceptualized as pointy and lengthy, dart-like machines. What would happen if they were more like flying wing? I'm hypothesizing a bit and I am not sure what ...
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Below what altitudes do shock waves form?

For a shock wave to form, the air must have a certain density. Surely in Thermosphere or even upper parts of Mesospheres the air is very thin. I was wondering if there is a formula related to the Mach ...
72 views

What should the inlet to throat area ratio be for a CD rocket nozzle on an aircraft flying at Mach 10?

I am analysing a rocket CD (convergent-divergent) nozzle at a altitude of 15,000m. I am stuck on how to calculate the areas so that at the throat of the nozzle Mach number equals to one. The ...
129 views

What missile defense systems would be used against hypersonic glide vehicles? [closed]

What missile defense systems would be used against hypersonic glide vehicles and cruise missiles (like Avangard or Sky Star)? What challenges would nations face developing them?
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What would an inlet look like on a hypersonic aircraft? Would it be fixed or movable?

What would an inlet look like on a hypersonic aircraft? Would it be rectangular or like a cone (assymetric). Would it move and if so how?
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What happens when a "ground effect" plane approaches the sound barrier?

Does the shock wave inhibit or contribute to lift? What is the ideal speed to fly near or on the speed of sound while using the ground effect?
340 views

Are there any hypersonic planes in service today?

Are there any hypersonic (Mach 5+) planes in service or officially being built? Or all the talk I here about the SR-72 rumor. Thanks!
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1 vote
168 views

What is the speed above which painting an aircraft black (or dark) results in lower skin temperature?

The Concorde is painted white for thermal reasons. If I understand correctly, it is done to reflect as much radiation as possible in order to lower tempereture. But when the skin is really hot (SR-71, ...
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1 vote
112 views

What are the effects of separation at hypersonic rarefied flows?

Shock wave causes an adverse pressure gradient which causes an airfoil to stall. Also because gas density is much lower boundary layer becomes laminar and unable to prevent separation. Correct me if ...
123 views

what is "Shock on shock heating"?

Can anybody enlighten me on the nature and physics behind what is referred to as Shock on Shock heating. Both , "Hypersonic: The Story of the North American X-15 , Jenkins and Landis" and "Lessons ...
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1 vote
585 views

Does an engine that combines an air-breathing rocket and non-air-breathing rocket exist?

Does a rocket engine that combines air-breathing and non-air-breathing modes exist? The advantage would be it would have to carry a smaller tank and less oxygen, leaving more room for payload on a ...
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Why Didn't the USSR Build An X-15?

In the history of aerospace engineering in the United States, the X-15 is lauded as a critical and necessary step on the path to manned spaceflight. Throttle-able chemical rocket propulsion systems, ...
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513 views

Why is a blunt trailing edge a better stabilizer at hypersonic speeds?

Here is what I read about the X-15 spaceplane: The X-15 had a thick wedge tail to enable it to fly in a steady manner at hypersonic speeds.[14] This produced a significant amount of drag at lower ...
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1 vote
173 views

What rotors would be best for atmospheric reentry?

What rotor blade set up would be the best for entering Earth atmosphere or to shed speed before landing in place of a parachute? I understand that the longer blades are more efficient, but are not as ...
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1 vote
330 views

Could liquid alkali metal fuels be used for ramjet/scramjet propulsion?

In particular, I'm thinking about lithium, but sodium could be considered as well. Lithium has low molecular weight, very high propellant density, and low melting point. At sufficiently high ...
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Are there any special considerations involved in designing manual flight controls for supersonic/hypersonic aircraft?

What things, if any, might need to be taken into account in the design of manual flight controls for supersonic or hypersonic aircraft that wouldn’t need to be taken into account with manual controls ...
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Can electroaerodynamic propulsion be used to circumvent sonic booms?

MIT researchers have created and flown the first plane that doesn’t require any moving parts. “Although it is still a long way off from commercial gas turbine propulsion … electroaerodynamic ...
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341 views

Could hydrazine be used as a scramjet propellant?

Hydrazine is used a monopropellant in Satellite OMS rockets. But interestingly enough, it's highly exothermic decomposition into ammonia, nitrogen, and hydrogen provides heat for an endothermic ...
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277 views

What mechanism or design aspect prevents jet blast from escaping the front of a Ramjet or scram jet?

Enormous air pressures result in the thrust of a Scram jet or ramjet engine, more so the pressure required to drive the aircraft forward at supersonic and hypersonic speeds. Given that these engines ...
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787 views

What technical problems stopped scramjets from being used on hypersonic aircraft?

I have been researching hypersonic aircraft and scramjet engines after running a few calculations looking at ramjet/rocket hybrids for making single stage to orbit vehicles. After doing the analysis ...
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Would pressurised air holes on supersonic aircraft mitigate the heat problem?

Would air holes or tubes of 50mm diameter blowing pressurised air outside the surface of a hypersonic or supersonic aircraft mitigate the problem of heat? They would be placed such that when they blow,...
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798 views

Is there currently any heat shielding and paint for speeds of up to Mach 6?

The Blackbird SR71 could travel faster than Mach 3 but its speed was limited to prevent its skin from melting. Its newer variant is said to be named the SR72 and it and other, civilian hypersonic ...
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What is the theoretical maximum speed of a rocket-powered aircraft in the atmosphere?

I read that the scram jet has a theoretical maximum speed of Mach 24. What is the theoretical maximum speed of a rocket-powered aircraft designed to operate in the atmosphere?
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Would a rotating skin design mitigate the heating problem limiting hypersonic flight?

Would a rotating skin design - where the skin of the aircraft rotates (powered either by an electric motor or the colluding wind) - mitigate the heating problem limiting hypersonic flight? Would a ...
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10k views

Are there any planes that have ramjet or scramjet engines?

Are there any planes that have ramjet or scramjet engines? If so, how did they reach the required mach speed for the engines to start functioning?
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Spinning wing heat dispersion dynamics for Mach 24 and beyond?

Could a spinning disk dropped from orbit survive speeds faster than conventional aircraft in our atmosphere? Does the rate of spin matter when dispersing heat? Does a spinning disk create stability ...
3k views

Won't sonic booms prevent Space X's BFR intercity transport plan from being acceptable?

Considering that Space X have just announced that their BFR can take anyone anywhere in the world in under 1 hour, that would be enormous speed, does this rocket not produce sonic boom? If not is it ...
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Is hypersonic flight possible with a Busemann's Biplane?

The modifications to the Busemann's Biplane design reported in this article have proven that it is possible to design a modified Busemann's Biplane wing design that actually produces lift at ...
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493 views

What is the maximum speed for regulation of sonic boom noise?

If fuel cost and fuel efficiency were not the issue, what is the maximum speed (air speed and ground speed) that business jets or airliners could travel at without exceeding the maximum noise and ...
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87 views

Sonic boom impediment to hypersonic passenger flight [duplicate]

Given that the ramjet and scram jet engines could achieve hypersonic flight, is sonic boom the major impediment to passenger hypersonic flight today? If so, why is it that space shuttles could travel ...
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376 views

Can a plane with air-breathing engines in level flight achieve enough velocity to make a single orbit?

A rocket uses engines that carry both fuel and oxidizer. Most are composed of multiple stages and lift a payload to orbit. They are able to burn their engines anywhere in or out of Earth's atmosphere ...
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22k views

What are maximum G forces humans can survive?

I read that very high g forces could kill a pilot, brain pushing into the skull. Is there a way of decreasing or surviving these forces and how would it work if you ignore aircraft capabilities. If ...
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2k views

Can hypersonic aircraft be agile without the G forces harming the pilot?

I read that high G forces associated with hypersonic flight could kill the pilot. Is there any way of making this survivable yet keeping agility at hyper sonic speeds (irrespective of the plane's ...
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585 views

Why does linear airfoil theory break down at hypersonic speeds?

Why can't we just extend linear supersonic theory beyond M = 5? I've looked at NASA papers discussing everything from geometric effects, air disassociation, and thermal coupling, but no clear and ...
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