Questions tagged [supersonic]
Use for questions relating to flight at speeds greater than sound and related effects from doing so.
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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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2answers
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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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2answers
101 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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Does an increase in Mach number lead to a decrease in Total Pressure Recovery (TPR) for supersonic inlets?
I am curious if the total pressure recover for supersonic inlets, in general, decrease for an increase in Mach number.
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8answers
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Could an airliner exceed Mach 1 in a zero-G power dive and safely recover?
(I looked for duplicates. I really did.)
Being as it is that "safety" and this are mutually exclusive:
I am stupid. I take a cruising A320, apply TOGA power, and push zero Gs until I exceed ...
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3answers
233 views
Was there ever a supersonic flight in a non-pressurized plane, and what is/would it be like for the pilot?
If you went supersonic in a plane that has no pressurized cockpit, would you be completely deaf (because of flying faster-than-sound)? Would it be dangerous to the pilot even if he/she was in an ...
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3answers
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Is it dangerous for a supersonic aircraft to fly at exactly Mach 1?
If a plane that is designed for supersonic flight, say the Concorde, kept flying at exactly the speed of sound, would there be any danger in that? If so, what could get dangerous at constant Mach 1 ...
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2answers
381 views
How much aerodynamic heating do jetliners endure?
At cruise altitude (~ 33,000 ft) and cruise airspeed (~ 500 mph) how much do present-day airliners heat up due to air friction during their journey? Probably not much because there's still ice on the ...
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Why aren't isentropic noses and tails used in supersonic aircraft?
An inside out paraboloid would theoretically produce isentropic compression for an inlet cone. But this question is about nose and tail cones on fuselages, and leading and trailing edges of wings.
An ...
5
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1answer
254 views
When and where are anti-ice required for supersonic flight?
Many aircraft have heating devices to prevent dangerous icing. Supersonic aircraft rapidly compress the air, leading to elevated temperatures. Concorde and Tu-144 used fuel as a heat sink.
How fast ...
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5answers
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Why was there no issue with the Tu-144 flying above land?
The Concorde didn't fly supersonically above land, it only could above the ocean. The Tu-144 however flew between Moscow and Almaty, so entirely above land; why did it fly like this? Didn't it have a ...
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1answer
121 views
How high can manned subsonic planes go?
What is the maximum altitude a manned plane that flies subsonically can reach? Subsonic airplanes can't go as high as super- and hypersonic ones of course, so record holders are the latter ones. But ...
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1answer
90 views
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 ...
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86 views
How is airspeed measured on supersonic aircraft? [duplicate]
Behind the shock wave air is subsonic, would that not cause an issue with the pitot tubes or any other sensor?
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1answer
142 views
Does the flow in an afterburner have to be subsonic?
This question is prompted by the problem on page 350 of the fluid mechanics book by Landau and Lifshitz. The problem states, "A small amount of heat is supplied over a short segment of a tube in ...
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1answer
3k views
Can a jet stream make a subsonic plane fly at a supersonic speed relative to the ground?
If a plane flies with a jet stream, its speed relative to the ground is the sum of the speed of the jet stream and the speed of the plane relative to the air in the jet stream. If the speeds that are ...
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2answers
509 views
Could one see stars from the Concorde in daytime?
The Concorde flew to an altitude of 60,000 ft (18.3 km) where stars should be visible at noon, aren't they? This question asks on how high stars become visible, and it is said Blackbird pilots could ...
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1answer
354 views
Why did the altimeter in an F-16 jump suddenly as it passed through Mach 1?
In this video, Destin — the creator of YouTube channel Smarter Every Day — rides in an F-16 with a USAF Thunderbirds pilot. If you start watching the video at the 11:06 mark, you will see what happens ...
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82 views
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?
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0answers
231 views
Why does drag coefficient decrease with Mach number in the supersonic regime?
I'm trying to understand why the drag coefficient decreases in the supersonic regime with Mach number. While it is easy show this using supersonic, potential flow theory, I'm looking for a more ...
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2answers
145 views
Why doesn't a wing in supersonic flow produce a shock that results in flow parallel to the leading edge?
When we look at a wedge in supersonic flow, a shock emanates from the leading edge such that the flow after the shock is turned and is parallel to the airfoil surface.
The shock angle is based on the ...
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1answer
121 views
How does wing shape impact shock structure?
I am trying to understand what the 3D shock structure would be for a wing in supersonic flow. Suppose we have a wing which is made of double-wedge airfoil cross-sections.
If we view the shock ...
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1answer
128 views
Does an airfoil in supersonic flow have zero circulation?
In incompressible flow, the Kutta-Joukowski theorem can be used to relate the lift (per unit span) to the circulation around an airfoil. However, if we look at an airfoil or the flat plate (see below) ...
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2answers
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Why does directional stability decrease at supersonic speeds?
As an aircraft accelerates through the transonic region from full subsonic to to full supersonic flow its directional or yaw stability decreases. What causes this reduction?
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298 views
Could an arrow planform be better for a supersonic aircraft than a delta? Why?
From this review paper
Page 11:
Strut-bracing for the SST allows very significant reductions in both vortex and wave DDL via an extreme arrow configuration and could be favourable to LFC via reduced ...
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1answer
164 views
Would supersonic bi/tri/multiplane wings have less lift interference drag than a subsonic version?
Biplane wings interfere with each other, reducing the total lift often to about only 20% more than a mono wing of the same chord and span.
But at supersonic speeds - say, Mach 2, where Mach angle is ...
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1answer
141 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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0answers
75 views
How to avoid shock (particularly Oblique shock) inside Cd nozzle?
Using the Area ratio (A/A*) and for the desired exit Mach number I have designed a cd nozzle. The Inlet total pressure (Po) and the total temperature (To) is calculated using Isentropic relations for ...
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1answer
134 views
How hot is supersonic intake air?
How hot is the air at the compressor inlet at supersonic speed? For instance the Concorde at mach 2.2 or other jet engines at even higher speeds.
2
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1answer
323 views
Does jet engine exhaust velocity relative to itself remain constant despite speed changes?
Maybe this is a stupid question.
I seem to have been told, the velocity of the exhaust leaving an airbreathing jet engine relative to the engine, is constant despite changes in airspeed. However, to ...
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1answer
175 views
How to identify shock waves and expansion waves on a representation of the mach number?
This image is a representation of the Mach number for $M_{\infty}=2.0$
I am very new to CFD and high speed aerodynamics. I'm trying to analyse this image, specifically to understand why the velocity ...
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228 views
Which 2-seat 4th generation fighter/engine/configuration (de-militarized) would the best supersonic long-range civilian private transport?
Seeing recently -with some surprise- that former military jets of fairly recent vintage can be bought e.g. here and operated by (skilled+licensed²+rich³) private individuals after all classified/...
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2answers
244 views
Why do shockwaves progressively move aft as speed increses?
As an airfoil moves from subsonic to supersonic, the shocks that develop over the surface move progressively toward the trailing edge. What is the physical explanation for this behavior?
As a side ...
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2answers
488 views
What are the aerodynamic design principles behind the “supersonic” propeller of Luigi Colani's C-309 racing plane?
One of Luigi Colani's designs that is particularly confusing to me is the second design iteration of the C-309 propeller racing airplane. Allegedly, its two propellers are designed to be supersonic ...
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3answers
345 views
Is it possible to use refrigeration technology to cool the skin of supersonic aircraft?
The fastest air breathing aircraft, the Blackbird SR71 flew at speeds above Mach 3. Its engines could achieve much higher speeds but were limited by the aircraft's skin which would melt due to ...
3
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1answer
283 views
Concorde thrust reversers engaged on parked aircraft, but not all engines?
Am I correct in interpreting this photo as showing one thrust reverser engaged, while the other is open? Do the thrust reversers fall into place on a fully powered down Concorde? Could this be caused ...
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3answers
275 views
Where to find NACA 65-110 Airfoil? [closed]
I'm working on a research project regarding the Bell XS-1, which used the NACA 65-110 airfoil. I haven't been able to find any data on this airfoil, and I'm wondering if anyone knows where I could?
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2answers
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How can an aircraft travel faster than speed of sound without breaking the sound barrier? [duplicate]
An excerpt from the BBC article here https://www.bbc.co.uk/news/uk-england-london-51433720
"Despite travelling faster than the speed of sound the plane would not have broken the sonic barrier as it ...
4
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1answer
121 views
Why is wave drag non-zero for a flow without shockwaves?
Wave drag is often defined as the component of drag that arises due to the presence of shockwaves. Shocks result in an entropy rise and a corresponding increase in drag. However, when using Supersonic ...
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1answer
265 views
How does a delta wing deal with supersonic boundary separation?
The question Why most of the supersonic or fighter aircraft use all-moving control surfaces? emphasis the importance of all moving stabilator for supersonic aircraft.
Many supersonic aircrafts ...
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1answer
195 views
What is the physical-based/theoretical reason why supersonic area ruling works?
Supersonic area ruling is used to reduce the drag rise that occurs as aircraft pass through the transonic regime. While it has been validated experimentally, what is the theoretical/physics-based ...
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1answer
143 views
About ramjet efficiency in supersonic speed. Is there an optimal speed?
I know there is an optimal speed for ramjet.
This are the results of my research.
The reason the efficiency increases with supersonic speed to an optimal value then decreases is related to the ...
8
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1answer
130 views
Since shock waves have non-negligible viscosity, why do the normal shock relations ignore friction/viscosity?
The normal shock relations (seen below) are derived by using steady, 1D, neglect potential, no shaft work, adiabatic and zero viscosity assumption. However, since shock waves are "thin regions of high ...
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92 views
Supersonic propellers for supersonic aircraft? [duplicate]
A propeller is a spinning wing. Supersonic wings work. So, provided that the blades are made wide-chord and thin like supersonic wings are, with a supersonic airfoil, can they not power efficiently a ...
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3answers
601 views
Do afterburners use excessive amounts of fuel?
The purpose of an afterburner is to provide additional thrust, and it is obvious that more fuel is needed for that.
But that is to be expected independent of an afterburner. That more thrust needs ...
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6answers
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Is an afterburner louder than the same jet engine without it?
I would speculate that an afterburner increases the noise because it is nearer to the exhaust. But it certainly causes so many changes in the exhaust flow that it could be less loud as well. It may ...
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1answer
5k views
Will you be able to hear a supersonic aircraft flying away from you?
I'm wondering if you could be able to hear the sound emitted by an aircraft say traveling at Mach 2 away from you.
I wondered if it might shift the emitted frequencies beyond the audible range. Would ...
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1answer
187 views
Is the “Boom” project vaporware or really going to happen? [closed]
Is this https://boomsupersonic.com viable or more vaporware?
Any solid information?
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0answers
133 views
What will happen to wing Vortices on supersonic aircraft?
Having looked at the new Aerion AS2 design I wondered whether anyone could tell me what happens to wingtip vortices at a cruise of Mach 1.4 with the strange wing shape of the AS2 design? I know that ...
3
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1answer
435 views
Why doesn't Concorde stall when passing Mach 1, where a normal airliner does?
As Jay Carr asked: What is a high speed stall?, Jan Hudec explained:
A difference from normal stall is that after supersonic flow separation the lift remains proportional to angle of attack and so ...
