Questions tagged [supersonic]

Use for questions relating to flight at speeds greater than sound and related effects from doing so.

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Ice Protection System for supersonic aircraft

How does a supersonic transport aircraft IPS system work? Does it work only for the engine nacelle or both engine and wing. I was thinking only for nacelle since the wings are usually highly swept. ...
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1 vote
2 answers
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Why can't supersonic flow work its way upstream?

I am reading this textbook today. And it described supersonic flow as follows: In a supersonic flow, because the local flow velocity is greater than the speed of sound, disturbances created at some ...
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Is fuel efficiency the only reason why hypersonic missiles don't use rocket engines?

Is fuel efficiency the only reason why hypersonic missiles don't use rocket engines? And why are rocket engine missiles relatively slow compared to scramjet missiles? In theory rocket engines can ...
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Are there reasons why hypersonic missiles can't be seen on radar? [closed]

military.com claims that hypersonic missiles cannot be seen on radar: And it's so fast that the air pressure in front of the weapon forms a plasma cloud as it moves, absorbing radio waves and making ...
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why normal surface pressure over wedged cone is greater than freestream pressure

I came across this question in "Fundamentals of Aerodynamics" by John Anderson, although I knew how to solve the question, I didn't understand why we had the surface pressure on the wedge 1....
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3 votes
1 answer
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How to calculate the inaccuracy in the "standard" turn radius equation, for supersonic airspeeds

I learned to calculate the radius of a level turn (r) using the function $ r = \frac{V^2} {g . tan(bank angle)}$. V is true airspeed, g is the local gravity constant. But now I have seen in the ...
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8 votes
2 answers
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At what altitude can the sonic boom no longer be heard at sea level?

As others have stated here, you can hear the sonic boom of planes flying by at a fairly high altitude, ~80 000 ft. At what altitude would the sonic boom no longer be noticable at sea level? To add to ...
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What's the relationship between mach number and drag force on an airplane?

From what i've read drag coefficient at mach 1 is several times (up to 10x) the drag coefficient below drag divergence mach number. It drops as the mach number increases. It's easy to find plots ...
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4 votes
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Thrust varaition of a Turbofan engine with altitude and mach number [duplicate]

my classmates and I are trying to find a mathematical model for a low bypass turbofan engine, we ended up finding a model given by Snorri on "General Aviation Aircraft Design", but the ...
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14 votes
1 answer
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What makes an engine suitable for supersonic flight?

I would like to know for example if someone can take the "core" of an CFM56 used on A320, redesign it by adding a supersonic intake, a convergent-divergent nozzle, and reduce its bypass ...
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Which would be the best placement of an engine for a supersonic buisness jet that has an intake of 2-D ramp? [duplicate]

I would also like to know if possible which would be the advantage/disadvantage of placing the engine under or over the wing for example.
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Are there planes designed for going supersonic in a dive only, not in leveled flight?

Are there any sub-/transsonic planes that are able to go supersonic in a dive without damage nor losing control but can't go above Mach 1 in horizontal flight? Some planes can go into leveled ...
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Would a ramjet be able to fly at 1% of sea level atmosphere and pure oxygen? [duplicate]

1% (0.01 atm) of the sea level pressure is a bit less pressure than at the SR-71 Blackbird's highest altitudes. If all that atmosphere was 100% oxygen (instead of 21%), would a (sc)ramjet still be ...
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10 votes
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What exactly is the pressure thrust component and why does it exist?

I'm teaching PowerPlants on a ATPL theory course and honestly have some trouble wrapping my head around this one: Most literature describes the term "pressure thrust" – as opposed to "...
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Are supersonic passenger aircraft still realistic? [duplicate]

I was wondering if supersonic passenger aircraft like Concorde or the Tupolev Tu 144 can still be made and flown profitably. The Tu 144 failed because it was poorly designed. And Concord failed ...
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11 votes
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Why did Concorde have a max pitch down attitude in supersonic flight?

In ITVV Concorde (documentary) as the flight's captain introduced the ADI (attitude director indicator) he explained the dotted line (circled above) as follows: [...] and the little orange dotted ...
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6 votes
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How does the drag coefficient behave at transonic and supersonic speeds for swept wing aircraft?

I was reading about wave drag and Concorde recently and found some contradictory information relating to drag. For example Wikipedia says: Afterburner was added to Concorde for take-off to cope with ...
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Why should Mach wave angle be less than wing sweep angle?

This is from my lecture notes: I see that this is so you can have subsonic flow over the wing planform, but why is this desirable? And are there more reasons? I can think of heat being an issue if ...
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Boundary Layer Ingestion - Would it also work at supersonic speeds?

I have searched the forum and the internet but can't find the answer to my question. Would the 10% increase in fuel efficiency from BLI function at supersonic speeds? The 10% increase is the number I ...
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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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1 vote
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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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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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8 answers
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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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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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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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5 votes
2 answers
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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 ...
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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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29 votes
5 answers
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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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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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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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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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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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15 votes
1 answer
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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14 votes
2 answers
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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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6 votes
1 answer
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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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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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1 vote
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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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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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1 vote
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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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3 votes
1 answer
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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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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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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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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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1 vote
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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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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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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.
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2 votes
1 answer
669 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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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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