# Questions tagged [supersonic]

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

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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 ...
6k views

### 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 ...
89 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 ...
24 views

### 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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### 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 ...
3k views

### Could a test crew replicate the 1961 DC-8 supersonic dive in a more modern airliner?

The first airliner to ever break the sound barrier was the DC-8, doing so in a semi-famous dive from 52,000' to 35,000' over the Edwards test range on August 21, 1961. Could this supersonic dive be ...
230 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 ...
368 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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### 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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### What was the first jet-powered supersonic aircraft?

Just to clarify: I am explicitly not referring to the Bell X-1, or any other early experimental supersonic aircraft that were rocket-powered. I'm curious as to the first supersonic aircraft powered by ...
288 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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### Was the Boeing 747 designed to be supersonic?

I heard a rumour that the Boeing 747 was originally designed for supersonic cruising. Is this correct? Are the airframe and wings able to cross the sound barrier without damage?
456 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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### 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 ...
250 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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### 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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### Why do suborbital planes feature H-tail and/or large wingtips?

Spaceplanes that are suborbital are mostly supersonic and feature H-tail or rather large wingtips. This looks to be similar to a H-tail configuration but I'm unsure abut how it works, which is why I ...
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 ...
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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### 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 ...
1k views

### How will the Boom SST not require an afterburner?

The company Boom is developing a supersonic airliner (SST). In one of their blog-entries1 they state they would not need to use after-burners because they use modern turbo-fan engines. Does this ...
584 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 ...
1k views

### If no low-speed compromises were made, what would an ideal Mach-3 wing look like?

Things like the Concorde and Tu-144 and many other supersonic craft need a wing that has good high-speed and good low-speed performance. After all, it needs to be able to take-off and land. Good low-...
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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### 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 ...
309 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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### 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 are the merits of an inlet cone/spike/centerbody vs. a 2D inlet?

And which is better for a scramjet? Is a 2D inlet basically a "2D cone"? Similar to how an aerospike engine is made "2D" in the linear aerospike? What's inside the cone/spike? Or is it just hollow?
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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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### How does supercruise thrust compare with static thrust ASL?

As I understand it, turbojet thrust decreases both with altitude due to rarefied air reducing massflow, and airspeed due to a smaller speed increase between intake and exhaust relative to the airframe....
193 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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### 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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### What is the effect of Mach number on efficiency, thrust and specific fuel consumption of a ramjet engine?

My graphs show that overall efficiency and thrust first increase, reach a peak and then fall in the supersonic range (M=1-5) whereas SFC first drops and then increases rapidly near M 5. Why does this ...
122 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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### Could Mach 1.4 be a better design point for SST?

There's been a number of recent proposals for design work on low-supersonic bizjets that would cruise at Mach 1.1-1.6, the common theme being avoiding a sonic boom. The conventional wisdom is to ...
1k views

### 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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### 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 ...
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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### 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 ...
133 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.
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### 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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### Why did the FAA ban all supersonic flights over the United States, rather than only supersonic flight in densely-populated areas?

A major part of why the Concorde was far less of a hit than predicted, and of why the many 1980s and 1990s supersonic transport projects never got off the drawing board, was that the FAA had banned ...
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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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### Aerospike nose cones for supersonic jets?

Not to be confused with aerospike nozzles. This is about the big pin-like rod in front of ICBM nose cones. This answer (from Space) about aerospike nose cones notes that one of the potential ...
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### Why are many military fighter aircraft designed to fly supersonic?

It is my understanding that these aircraft rarely fly at supersonic speeds anyway—the ordnance they carry, the increased fuel burn (even with supercruise), and the increased chance of detection make ...
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### 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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### 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/...