# What Mach Is The Speed Of Light?

Mach 874,030 Answer and Explanation: The speed of light is Mach 874,030. This is because the speed of light in air is 874,030 times faster than the speed of sound in air. Sound travels are a speed of 1234 km/hr while light travels at 1,078,553,020 km/hr.

### Is Mach 1 the speed of sound or light?

What does Mach 1 mean? A Mach number is the ratio of an object’s speed in a given medium to the speed of sound in that medium. Mach 1, then, is the speed of sound, around 761 mph at sea level on a standard day. The term is also used as a metaphor for high speeds more generally.

#### What is Mach 10 speed?

NASA – Mach 10 Marvel Blazing like a meteor through the sky at nearly Mach 10 on Nov.16, 2004, NASA’s third X-43A scramjet flight looked as easy as the second flight did months earlier, but looks are deceiving. Image right: Infrared image of the world-record Mach 6.8 flight of the second X-43A scramjet on March 27, 2004.U.S.

1. Army photo.
2. This high-risk flight, following the March 2004 world record-smashing Mach 6.8 flight, demanded that no details be overlooked, no matter how small.
3. When the second X-43A research vehicle flew at Mach 6.8, or nearly seven times the speed of sound (the speed of sound is about 760 mph at sea level), the friction-generated 2600-degree Fahrenheit temperature on the leading edges of the vehicle’s horizontal tails was more than enough to melt unprotected metal.

Carbon-carbon thermal protection material kept them cool enough to withstand the searing heat. This is a challenge for even the most advanced thermal protection materials. As the final X-43A flew, blistering temperatures created by the nearly Mach 10 (7000 mph) speed were in the neighborhood of 3600 degrees, the hotspot this time being the nose of the vehicle.

• The heat distribution was different this time around due to material differences.
• For further protection, Vehicle 3 had additional thermal coatings on the horizontal tails’ carbon-carbon leading edges.
• Another change in preparation for the third flight was the fact that Vehicle 3’s vertical tails were solid, as opposed to the ribbed structure construction used on Vehicles 1 and 2.

Carbon-carbon leading edges were added to the vertical tails as well. The separation of the research vehicle from the booster was performed at a higher speed than the Mach 7 flight, but dynamic pressure was lower due to the planned higher separation altitude this time.

• An important product of flight research is data collection, and one of the prime data objectives for the Hyper-X program was validation of scramjet ground predictions.
• Prior to the Mach 7 flight, engineers were able to use hypersonic wind tunnel data for risk reduction tests.
• However, they couldn’t do this in preparation for the Mach 10 flight, as fewer ground test facilities were available.

“One of the more significant challenges we faced in preparing for the Mach 10 flight was the reduced amount of ground test data,” said Laurie Marshall, NASA Dryden Flight Research Center’s X-43A Vehicle 3 chief engineer. “For Flight 2 we were able to do more wind tunnel work than we could for Flight 3.

• In some cases the same tests couldn’t be repeated; the facilities and capabilities just aren’t there.
• So having to design a vehicle and engine that could survive the environment and complete the mission successfully without some of that data was a challenge,” Marshall said.
• Another of the exciting things about the Mach 10 flight of the X-43A was that NASA gathered data that has never been obtained before.

“That’s why we do this, that’s why we fly,” Marshall said. “The research data that we obtained with this flight can’t be obtained on the ground.” Gray Creech NASA Dryden Flight Research Center : NASA – Mach 10 Marvel

### How fast is the speed of light in?

Light from a stationary source travels at 300,000 km/sec (186,000 miles/sec).

## Can a human survive Mach 20?

Why the Human Body Can’t Handle Heavy Acceleration Our bodies are surprisingly resilient in many situations, but rapid acceleration is not one of them. While the human body can withstand any constant speed—be it 20 miles per hour or 20 billion miles per hour—we can only change that rate of travel relatively slowly. Speed up or slow down too quickly and it’s lights out for you, permanently.

## Has anyone hit Mach 20?

The results are in from last summer’s attempt to test new technology that would provide the Pentagon with a lightning-fast vehicle, capable of delivering a military strike anywhere in the world in less than an hour. In August the Pentagon’s research arm, known as the Defense Advanced Research Projects Agency, or DARPA, carried out a test flight of an experimental aircraft capable of traveling at 20 times the speed of sound.

The arrowhead-shaped unmanned aircraft, dubbed Falcon Hypersonic Technology Vehicle 2, blasted off from Vandenberg Air Force Base, northwest of Santa Barbara, into the upper reaches of the Earth’s atmosphere aboard an eight-story Minotaur IV rocket made by Orbital Sciences Corp. After reaching an undisclosed altitude, the aircraft jettisoned from its protective cover atop the rocket, then nose-dived back toward Earth, leveled out and glided above the Pacific at 20 times the speed of sound, or Mach 20.

The plan was for the Falcon to speed westward for about 30 minutes before plunging into the ocean near Kwajalein Atoll, about 4,000 miles from Vandenberg. But it was ended about nine minutes into flight for unknown reasons. The launch had received worldwide attention and much fanfare, but officials didn’t provide much information on why the launch failed.

1. On Friday, DARPA said in a statement that the searing high speeds caused portions of the Falcon’s skin to peel from the aerostructure.
2. The resulting gaps created strong shock waves around the vehicle as it traveled nearly 13,000 mph, causing it to roll abruptly.
3. The Falcon, which is built by Lockheed Martin Corp., is made of durable carbon composite material, which was expected to keep the aircraft’s crucial internal electronics and avionics – only a few inches away from the surface – safe from the fiery hypersonic flight.

Surface temperatures on the Falcon were expected to reach more than 3,500 degrees, hot enough to melt steel. “The initial shock wave disturbances experienced during second flight, from which the vehicle was able to recover and continue controlled flight, exceeded by more than 100 times what the vehicle was designed to withstand,” DARPA Acting Director Kaigham J.

1. Gabriel said in a statement.
2. That’s a major validation that we’re advancing our understanding of aerodynamic control for hypersonic flight.” The flight successfully demonstrated stable aerodynamically controlled flight at speeds up to Mach 20 for nearly three minutes.
3. Sustaining hypersonic flight has been an extremely difficult task for aeronautical engineers over the years.

While supersonic means that an object is traveling faster than the speed of sound, or Mach 1, “hypersonic” refers to an aircraft going five times that speed or more. The Falcon hit Mach 20. At that speed, an aircraft could zoom from Los Angeles to New York in less than 12 minutes – 22 times faster than a commercial airliner.

1. Take a look at what that looks like from the ground in the video below.
2. The August launch was the second flight of the Falcon technology.
3. The first flight, which took place in April 2010, also ended prematurely with only nine minutes of flight time.
4. There aren’t any more flights scheduled for the Falcon program, which began in 2003 and cost taxpayers about \$320 million.

RELATED: Flying car aims to take wing in the commercial market F-35 fighter jet’s escalating costs are on Washington’s radar With so much at stake, companies turn to hired hackers Follow Hennigan on Twitter @wjhenn

## Can anything fly at Mach 1?

As an aircraft moves through the air, the air molecules near the aircraft are disturbed and move around the aircraft. If the aircraft passes at a low speed, typically less than 250 mph, the density of the air remains constant. But for higher speeds, some of the energy of the aircraft goes into compressing the air and locally changing the density of the air.

1. This compressibility effect alters the amount of resulting force on the aircraft.
2. The effect becomes more important as speed increases.
3. Near and beyond the speed of sound, about 330 m/s or 760 mph, small disturbances in the flow are transmitted to other locations isentropically or with constant entropy.

But a sharp disturbance generates a shock wave that affects both the lift and drag of an aircraft. The ratio of the speed of the aircraft to the speed of sound in the gas determines the magnitude of many of the compressibility effects. Because of the importance of this speed ratio, aerodynamicists have designated it with a special parameter called the Mach number in honor of Ernst Mach, a late 19th century physicist who studied gas dynamics.

Subsonic conditions occur for Mach numbers less than one, M < 1, For the lowest subsonic conditions, compressibility can be ignored. As the speed of the object approaches the speed of sound, the flight Mach number is nearly equal to one, M = 1, and the flow is said to be transonic, At some places on the object, the local speed exceeds the speed of sound. Compressibility effects are most important in transonic flows and lead to the early belief in a sound barrier, Flight faster than sound was thought to be impossible. In fact, the sound barrier was only an increase in the drag near sonic conditions because of compressibility effects. Because of the high drag associated with compressibility effects, aircraft do not cruise near Mach 1. Supersonic conditions occur for Mach numbers greater than one, 1 < M < 3, Compressibility effects are important for supersonic aircraft, and shock waves are generated by the surface of the object. For high supersonic speeds, 3 < M < 5, aerodynamic heating also becomes very important for aircraft design. For speeds greater than five times the speed of sound, M > 5, the flow is said to be hypersonic, At these speeds, some of the energy of the object now goes into exciting the chemical bonds which hold together the nitrogen and oxygen molecules of the air. At hypersonic speeds, the chemistry of the air must be considered when determining forces on the object. The Space Shuttle re-enters the atmosphere at high hypersonic speeds, M ~ 25, Under these conditions, the heated air becomes an ionized plasma of gas and the spacecraft must be insulated from the high temperatures.

For supersonic and hypersonic flows, small disturbances are transmitted downstream within a cone. The trigonometric sine of the cone angle b is equal to the inverse of the Mach number M and the angle is therefore called the Mach angle, sin(b) = 1 / M There is no upstream influence in a supersonic flow ; disturbances are only transmitted downstream. The Mach number appears as a similarity parameter in many of the equations for compressible flows, shock waves, and expansions, When wind tunnel testing, you must closely match the Mach number between the experiment and flight conditions. It is completely incorrect to measure a drag coefficient at some low speed (say 200 mph) and apply that drag coefficient at twice the speed of sound (approximately 1400 mph, Mach = 2.0). The compressibility of the air alters the important physics between these two cases. The Mach number depends on the speed of sound in the gas and the speed of sound depends on the type of gas and the temperature of the gas. The speed of sound varies from planet to planet. On Earth, the atmosphere is composed of mostly diatomic nitrogen and oxygen, and the temperature depends on the altitude in a rather complex way. Scientists and engineers have created a mathematical model of the atmosphere to help them account for the changing effects of temperature with altitude. Mars also has an atmosphere composed of mostly carbon dioxide. There is a similar mathematical model of the Martian atmosphere. We have created an atmospheric calculator to let you study the variation of sound speed with planet and altitude. Here’s another JavaScript program to calculate speed of sound and Mach number for different planets, altitudes, and speed. You can use this calculator to determine the Mach number of a aircraft at a given speed and altitude on Earth or Mars. Press-> Output Speed Speed of Sound Mach To change input values, click on the input box (black on white), backspace over the input value, type in your new value, and hit the Enter key on the keyboard (this sends your new value to the program). You will see the output boxes (yellow on black) change value. You can use either English or Metric units and you can input either the Mach number or the speed by using the menu buttons. Just click on the menu button and click on your selection. If you are an experienced user of this calculator, you can use a sleek version of the program which loads faster on your computer and does not include these instructions. You can also download your own copy of the program to run off-line by clicking on this button:

#### Can a human go Mach 10?

Could The Human Body Survive Mach 10? – Tom Cruise’s character’s feat of Mach 10 speed in Top Gun: Maverick is one scientifically improbable stunt out of many featured in the film. That being said, is it possible for the human body to be able to withstand such acceleration? The most likely answer is a resounding no.

• Mach 10 speed has never been achieved by a manned aircraft, though, so it has never been tested.
• Mach 10 has, however, been achieved by a spacecraft – on November 16, 2004, NASA launched the X-43A, an air-breathing hypersonic vehicle, and was able to reach real Mach 10 while being pushed into the atmosphere.

But that was an unmanned craft. The problem with humans withstanding such a speed has to do with the acceleration needed to reach it, and the resultant G-force. A normal human could withstand up to around 4-6Gs. Real fighter pilots, on the other hand, are able to take a whopping 9Gs for a second or two, but that only comes with extensive training.

## Is anything faster than Mach 1?

From Wikipedia, the free encyclopedia Supersonic speed is the speed of an object that exceeds the speed of sound ( Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately 343.2 m/s (1,126 ft/s; 768 mph; 667.1 kn; 1,236 km/h). Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic,

Flights during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic, This occurs typically somewhere between Mach 0.8 and Mach 1.2. Sounds are traveling vibrations in the form of pressure waves in an elastic medium. Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium.

In gases, sound travels longitudinally at different speeds, mostly depending on the molecular mass and temperature of the gas, and pressure has little effect. Since air temperature and composition varies significantly with altitude, the speed of sound, and Mach numbers for a steadily moving object may change.

#### Did Tom Cruise fly Mach 10?

Top Gun: Maverick has achieved Mach 10. In fact, if you’ve seen the film, you know that Pete “Maverick” Mitchell (Tom Cruise, of course) does achieve the previously unthinkable when he hits Mach 10 in the opening sequence of the film, working as a test pilot for the Navy.

The scene is thrilling and ends with Maverick, once again, getting screamed at by a Navy official (played by Jon Hamm, no less), only to be told he’s been summoned by an even higher-ranking officer, one Admiral Kazansky (you remember him from the original Top Gun as Iceman, played by Val Kilmer) to teach a bunch of Top Gun pilots how to handle a seemingly impossible mission.

In real life, the mission of the film, to delight and seduce millions of people back into the movie theater to see Cruise return to the role that made him famous way back in 1986, has been a massive success. Top Gun: Maverick has soared into the record books for the second weekend in a row.

1. After a historic opening over Memorial Day Weekend, T op Gun: Maverick zoomed to an astonishing \$86 million haul in 4,751 theaters in North America in its second weekend.
2. That’s a very tiny drop of 32% from its gangbusters opening, the smallest second-week drop for a movie that opened to \$100 million or more.

It’s proof of the film’s pull on moviegoers, who have poured into theaters to see Cruise and the cast flying in real Navy jets. Maverick ‘s superb craft and emotional connection to the original have made it irresistible, highlighted by the relationship between Mav and Bradley “Rooster” Bradshaw (Miles Teller), the son of Mav’s long-dead best friend and radar intercept pilot, Goose (Anthony Edwards).

Most blockbusters like Maverick see a significant drop after their opening weekend, even beloved, critically lauded, massively successful blockbusters like Spider-Man: No Way Home, which dropped 67% after its opening weekend. Yet Maverick keeps cruising. So far, the global haul for the film is \$548 million, which would be an incredible success even if you were measuring the movie by pre-pandemic standards.

It’s also proof that the time everyone involved took to make sure they got Maverick right paid off. Filmgoers are responding to a film that was made with great care, and one that gives us some old-school movie magic with practical effects, big emotions, and a decent dollop of nostalgia.

1. It’s a winning formula that, crucially, doesn’t feel formulaic.
2. It seems like a safe bet that Top Gun: Maverick could keep flying high into its third weekend in theaters.
3. For more on Top Gun: Maverick, check out these stories: Tom Cruise’s Historic “Top Gun: Maverick” Opening Weekend Going to Flight School With “Top Gun: Maverick” Stars Glen Powell & Greg Tarzan Davis “Top Gun: Maverick” Gets Five-Minute Standing Ovation at Cannes “Top Gun: Maverick” Soars as Critics Hail Riveting Sequel Featured image: Tom Cruise plays Capt.
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Pete “Maverick” Mitchell in Top Gun: Maverick from Paramount Pictures, Skydance and Jerry Bruckheimer Films. Credit: Scott Garfield. © 2019 Paramount Pictures Corporation.

#### Is anything faster than Mach 5?

Hypersonic – At this speed, an aircraft is traveling faster than Mach 5. The hypersonic, a joint venture that NASA conducted with the Air Force, the Navy, and North American Aviation, Inc., flew at Mach 6.7. The X-15 flew from 1958 to 1969 and provided insights that later contributed to the Mercury, Gemini, and Apollo piloted spaceflight programs.

1. It also helped inform the Space Shuttle, which flies at hypersonic speeds while in the earth’s upper atmosphere.
2. It slows down to supersonic speeds as it re-enters the lower part of the earth’s atmosphere.) Most recently, China launched its experimental “waverider” hypersonic aircraft, which soared at about Mach-5.5 for 400 seconds (after being carried by a rocket to an altitude of 18 miles or 30km).

The reason for the distinction between supersonic and hypersonic is due to temperature changes. At speeds above Mach 5, most metals will melt or become so soft that they can’t be used for any type of structure. As a result, hypersonic aircraft must go to extreme measures for heat protection (such as the tiles and blankets protecting the space shuttle).

• While it’s challenging to imagine what happens to an aircraft at such temperatures, here are two examples: aluminum will melt at approximately 1,200° F or 648° C and steel will melt at approximately 2,500° F or 1,371° C.
• To learn more about speed versus temperature, click for a great blog about why air is hot when you fly fast and why there’s no such thing as “cooling air” once you’ve achieved Mach 1.

: Beyond supersonic? Defining the 4 speeds of flight

#### How fast is hypersonic?

A hypersonic weapon is a weapon capable of travelling at hypersonic speed, defined as between 5 and 25 times the speed of sound or about 1 to 5 miles per second (1.6 to 8.0 km/s).

### How fast is 100% of light?

Home References Science & Astronomy

The speed of light is a speed limit on everything in our universe. Or is it? (Image credit: Getty/ Yuichiro Chino) The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That’s about 186,282 miles per second — a universal constant known in equations as “c,” or light speed.

• According to physicist Albert Einstein ‘s theory of special relativity, on which much of modern physics is based, nothing in the universe can travel faster than light.
• The theory states that as matter approaches the speed of light, the matter’s mass becomes infinite.
• That means the speed of light functions as a speed limit on the whole universe,

The speed of light is so immutable that, according to the U.S. National Institute of Standards and Technology (opens in new tab), it is used to define international standard measurements like the meter (and by extension, the mile, the foot and the inch).

Through some crafty equations, it also helps define the kilogram and the temperature unit Kelvin, But despite the speed of light’s reputation as a universal constant, scientists and science fiction writers alike spend time contemplating faster-than-light travel. So far no one’s been able to demonstrate a real warp drive, but that hasn’t slowed our collective hurtle toward new stories, new inventions and new realms of physics.

Related: Special relativity holds up to a high-energy test

#### How fast is 100% light speed?

Physics > Train of Thought > Light Speed. Light is fast! It can reach the universal speed limit — 186,000 miles per second. (If you could travel as fast as light, the universe would look very different.)

#### Why is light so fast?

Making it mean something – Continued measurements over the course of the next few centuries solidified the measurement of the speed of light, but it wasn’t until the mid-1800s when things really started to come together. That’s when the physicist James Clerk Maxwell accidentally invented light.

• Maxwell had been playing around with the then-poorly-understood phenomena of electricity and magnetism when he discovered a single unified picture that could explain all the disparate observations.
• Laying the groundwork for what we now understand to be the electromagnetic force, in those equations he discovered that changing electric fields can create magnetic fields, and vice versa.

This allows waves of electricity to create waves of magnetism, which go on to make waves of electricity and back and forth and back and forth, leapfrogging over each other, capable of traveling through space. And when he went to calculate the speed of these so-called electromagnetic waves, Maxwell got the same number that scientists had been measuring as the speed of light for centuries.

Ergo, light is made of electromagnetic waves and it travels at that speed, because that is exactly how quickly waves of electricity and magnetism travel through space. And this was all well and good until Einstein came along a few decades later and realized that the speed of light had nothing to do with light at all.

With his special theory of relativity, Einstein realized the true connection between time and space, a unified fabric known as space-time. But as we all know, space is very different than time. A meter or a foot is very different than a second or a year.

They appear to be two completely different things. So how could they possibly be on the same footing? There needed to be some sort of glue, some connection that allowed us to translate between movement in space and movement in time. In other words, we need to know how much one meter of space, for example, is worth in time.

What’s the exchange rate? Einstein found that there was a single constant, a certain speed, that could tell us how much space was equivalent to how much time, and vice versa. Einstein’s theories didn’t say what that number was, but then he applied special relativity to the old equations of Maxwell and found that this conversion rate is exactly the speed of light.

Of course, this conversion rate, this fundamental constant that unifies space and time, doesn’t know what an electromagnetic wave is, and it doesn’t even really care. It’s just some number, but it turns out that Maxwell had already calculated this number and discovered it without even knowing it. That’s because all massless particles are able to travel at this speed, and since light is massless, it can travel at that speed.

And so, the speed of light became an important cornerstone of modern physics. But still, why that number, with that value, and not some other random number? Why did nature pick that one and no other? What’s going on? Related: The genius of Albert Einstein: his life, theories and impact on science

### Is Mach 27 possible?

Hypersonics pose a serious challenge to air defenses – A villager passes by debris of private houses ruined in a Russian attack in a village in Zolochevsky district in the Lviv region, Ukraine, on Thursday. Ukrainian forces said the Russian barrage included the use of hypersonic missiles. Mykola Tys / AP Hypersonic missiles such as the Kinzhal are a fairly new breed of weapon that combine superior speed with the ability to maneuver to evade being shot down.

1. Not only are they difficult to detect, but they make radical and unpredictable course changes as they get close to a target.
2. The, unveiled by Russian President Vladimir Putin five years ago, can accelerate to Mach 4 — four times the speed of sound — and may be capable of speeds of up to Mach 10, with a range to about 1,250 miles.

The missile is also believed to be nuclear-capable. An even more sophisticated weapon, Russia’s Avangard hypersonic glide vehicle, can fly at speeds as high as Mach 27, according to the Kremlin. Another hypersonic, the Zircon anti-ship missile, has also reportedly been developed, but there are no reports of the Zircon or Avangard being used in combat.

## Is Mach 15 possible?

Can a hypersonic plane reach Mach 15? – A: Mach 15 is about 5104.35 meters per second. The only plane that was slated to move that fast was the (unmanned) NASA X-43, which recorded speeds over Mach 10. The X-43A used a rocket booster to get to speed after being dropped out of a B-52. Posted on June 6, 2015 at 7:51 am Categories:

## How fast is 1 g-force?

Acceleration and forces – The term g-“force” is technically incorrect as it is a measure of acceleration, not force. While acceleration is a vector quantity, g-force accelerations (“g-forces” for short) are often expressed as a scalar, with positive g-forces pointing downward (indicating upward acceleration), and negative g-forces pointing upward.

Thus, a g-force is a vector of acceleration. It is an acceleration that must be produced by a mechanical force, and cannot be produced by simple gravitation. Objects acted upon only by gravitation experience (or “feel”) no g-force, and are weightless. g-forces, when multiplied by a mass upon which they act, are associated with a certain type of mechanical force in the correct sense of the term “force”, and this force produces compressive stress and tensile stress,

Such forces result in the operational sensation of weight, but the equation carries a sign change due to the definition of positive weight in the direction downward, so the direction of weight-force is opposite to the direction of g-force acceleration: Weight = mass × −g-force The reason for the minus sign is that the actual force (i.e., measured weight) on an object produced by a g-force is in the opposite direction to the sign of the g-force, since in physics, weight is not the force that produces the acceleration, but rather the equal-and-opposite reaction force to it.

If the direction upward is taken as positive (the normal cartesian convention) then positive g-force (an acceleration vector that points upward) produces a force/weight on any mass, that acts downward (an example is positive-g acceleration of a rocket launch, producing downward weight). In the same way, a negative-g force is an acceleration vector downward (the negative direction on the y axis), and this acceleration downward produces a weight-force in a direction upward (thus pulling a pilot upward out of the seat, and forcing blood toward the head of a normally oriented pilot).

If a g-force (acceleration) is vertically upward and is applied by the ground (which is accelerating through space-time) or applied by the floor of an elevator to a standing person, most of the body experiences compressive stress which at any height, if multiplied by the area, is the related mechanical force, which is the product of the g-force and the supported mass (the mass above the level of support, including arms hanging down from above that level).

• At the same time, the arms themselves experience a tensile stress, which at any height, if multiplied by the area, is again the related mechanical force, which is the product of the g-force and the mass hanging below the point of mechanical support.
• The mechanical resistive force spreads from points of contact with the floor or supporting structure, and gradually decreases toward zero at the unsupported ends (the top in the case of support from below, such as a seat or the floor, the bottom for a hanging part of the body or object).

With compressive force counted as negative tensile force, the rate of change of the tensile force in the direction of the g-force, per unit mass (the change between parts of the object such that the slice of the object between them has unit mass), is equal to the g-force plus the non-gravitational external forces on the slice, if any (counted positive in the direction opposite to the g-force).

For a given g-force the stresses are the same, regardless of whether this g-force is caused by mechanical resistance to gravity, or by a coordinate-acceleration (change in velocity) caused by a mechanical force, or by a combination of these. Hence, for people all mechanical forces feels exactly the same whether they cause coordinate acceleration or not.

For objects likewise, the question of whether they can withstand the mechanical g-force without damage is the same for any type of g-force. For example, upward acceleration (e.g., increase of speed when going up or decrease of speed when going down) on Earth feels the same as being stationary on a celestial body with a higher surface gravity,

Gravitation acting alone does not produce any g-force; g-force is only produced from mechanical pushes and pulls. For a free body (one that is free to move in space) such g-forces only arise as the “inertial” path that is the natural effect of gravitation, or the natural effect of the inertia of mass, is modified.

Such modification may only arise from influences other than gravitation. Examples of important situations involving g-forces include:

• The g-force acting on a stationary object resting on the Earth’s surface is 1 g (upwards) and results from the resisting reaction of the Earth’s surface bearing upwards equal to an acceleration of 1 g, and is equal and opposite to gravity. The number 1 is approximate, depending on location.
• The g-force acting on an object in any weightless environment such as free-fall in a vacuum is 0 g.
• The g-force acting on an object under acceleration can be much greater than 1 g, for example, the dragster pictured at top right can exert a horizontal g-force of 5.3 when accelerating.
• The g-force acting on an object under acceleration may be downwards, for example when cresting a sharp hill on a roller coaster.
• If there are no other external forces than gravity, the g-force in a rocket is the thrust per unit mass. Its magnitude is equal to the thrust-to-weight ratio times g, and to the consumption of delta-v per unit time.
• In the case of a shock, e.g., a collision, the g-force can be very large during a short time.

A classic example of negative g-force is in a fully inverted roller coaster which is accelerating (changing velocity) toward the ground. In this case, the roller coaster riders are accelerated toward the ground faster than gravity would accelerate them, and are thus pinned upside down in their seats.

In this case, the mechanical force exerted by the seat causes the g-force by altering the path of the passenger downward in a way that differs from gravitational acceleration. The difference in downward motion, now faster than gravity would provide, is caused by the push of the seat, and it results in a g-force toward the ground.

All “coordinate accelerations” (or lack of them), are described by Newton’s laws of motion as follows: The Second Law of Motion, the law of acceleration states that: F =  ma., meaning that a force F acting on a body is equal to the mass m of the body times its acceleration a, This acrobatic airplane is pulling up in a +g maneuver; the pilot is experiencing several g’s of inertial acceleration in addition to the force of gravity. The cumulative vertical axis forces acting upon his body make him momentarily ‘weigh’ many times more than normal.

In an airplane, the pilot’s seat can be thought of as the hand holding the rock, the pilot as the rock. When flying straight and level at 1 g, the pilot is acted upon by the force of gravity. His weight (a downward force) is 725 newtons (163 lb f ). In accordance with Newton’s third law, the plane and the seat underneath the pilot provides an equal and opposite force pushing upwards with a force of 725 N (163 lb f ).

This mechanical force provides the 1.0 g-force upward proper acceleration on the pilot, even though this velocity in the upward direction does not change (this is similar to the situation of a person standing on the ground, where the ground provides this force and this g-force).

If the pilot were suddenly to pull back on the stick and make his plane accelerate upwards at 9.8 m/s 2, the total g‑force on his body is 2 g, half of which comes from the seat pushing the pilot to resist gravity, and half from the seat pushing the pilot to cause his upward acceleration—a change in velocity which also is a proper acceleration because it also differs from a free fall trajectory.

Considered in the frame of reference of the plane his body is now generating a force of 1,450 N (330 lb f ) downwards into his seat and the seat is simultaneously pushing upwards with an equal force of 1,450 N (330 lb f ). Unopposed acceleration due to mechanical forces, and consequentially g-force, is experienced whenever anyone rides in a vehicle because it always causes a proper acceleration, and (in the absence of gravity) also always a coordinate acceleration (where velocity changes).

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Whenever the vehicle changes either direction or speed, the occupants feel lateral (side to side) or longitudinal (forward and backwards) forces produced by the mechanical push of their seats. The expression “1 g = 9.806 65 m/s 2 ” means that for every second that elapses, velocity changes 9.806 65 metres per second (≡ 35.303 94 km/h ).

This rate of change in velocity can also be denoted as 9.806 65 (metres per second) per second, or 9.806 65 m/s 2, For example: An acceleration of 1 g equates to a rate of change in velocity of approximately 35 kilometres per hour (22 mph) for each second that elapses.

1. Therefore, if an automobile is capable of braking at 1 g and is traveling at 35 kilometres per hour (22 mph), it can brake to a standstill in one second and the driver will experience a deceleration of 1 g.
2. The automobile traveling at three times this speed, 105 km/h (65 mph), can brake to a standstill in three seconds.

In the case of an increase in speed from 0 to v with constant acceleration within a distance of s this acceleration is v 2 /(2s). Preparing an object for g-tolerance (not getting damaged when subjected to a high g-force) is called g-hardening. This may apply to, e.g., instruments in a projectile shot by a gun,

### Has a jet ever went Mach 10?

NASA’s X-43A Scramjet Achieves Record-Breaking Mach 10 Speed Using Model-Based Design Design and automatically generate flight control software for a scramjet vehicle traveling at Mach 10 speed Use Simulink to model and validate control systems, Simulink Coder to automatically generate flight code, and MATLAB to process and analyze postflight data

Reduced development time by months Accurately predicted separation clearance Aided in achieving SEI CMM Level 5 process rating

“Our autopilot worked on the first try, which is amazing given that a vehicle like this had never been flown before. MathWorks tools helped us design and implement control systems that kept the vehicle stable throughout the flight.” Dave Bose, Analytical Mechanics Associates On November 16, 2004, NASA made history by launching the X-43A, the first-ever air-breathing hypersonic vehicle, into the atmosphere, achieving Mach 10 speed.

The X-43A separated from its booster and accelerated on scramjet power at nearly ten times the speed of sound (7000 MPH) at roughly 110,000 feet. The experiment enabled NASA to validate key propulsion and related technologies for air-breathing hypersonic aircraft. Dubbed Hyper-X, the project was a collaborative effort involving engineers from a variety of organizations, including NASA Dryden Flight Research Center, NASA Langley Research Center, Analytical Mechanics Associates (AMA), and Boeing PhantomWorks.

These teams used MathWorks tools for Model-Based Design to develop and automatically generate flight code for the vehicle’s propulsion and flight control systems. They also used MATLAB ® to analyze preflight assumptions and postflight results. NASA was tasked with developing controls for the X-43A and its subsystems, including flight control, propulsion, actuators, and sensors.

1. These controls would keep the unmanned vehicle stable within a half-degree angle-of-attack and ensure sufficient clearance between the research vehicle and the adaptor on the front of the booster when the two parts separated.
2. The engineers would need to complete the project under a wide range of environmental conditions and an uncharted flight regime.

Because this unique project involved multiple teams and a highly complex design, NASA would need a common modeling environment and a proven design process based on reliable models. With a high likelihood that system requirements and models would change as the program matured, they also sought to automate development and minimize manual coding and debugging.

1. Finally, NASA would need tools for efficiently analyzing gigabytes of multidimensional telemetry data.
2. The Guidance, Navigation, and Control team at NASA worked with Boeing and AMA to develop the propulsion and flight control laws for the X-43A scramjet and integrate them into the onboard system.
3. All teams collaborated on the project by applying Model-Based Design with MathWorks tools.

“There aren’t any software packages out there that can match the capabilities of MathWorks tools,” says Dave Bose, vice president of modeling and simulation at AMA. “From the team’s perspective, it really was an easy decision to choose MathWorks tools.”

#### Can anything go Mach 25?

From Wikipedia, the free encyclopedia Hypersonic flight is flight through the atmosphere below altitudes of about 90 km at speeds greater than Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Speeds of Mach 25+ have been achieved below the thermosphere as of 2020.

## What’s the highest Mach we’ve gone?

The Top Ten fastest planes in the World – Before we start – here is a nice video showing you the 10 fastest planes in the world: There are very many aircraft that has exceeded the speed of Mach 2.0. Some of them are research aircraft, some are military and some are simply flying for reconnaissance purposes.

But there is always something special with supersonic aircraft. Just imagine flying at an altitude of 5 kilometres, hearing a “go” from the radio and pushing that throttle backwards while feeling the 100+kN engine accelerating you to speeds higher than any other life form has ever been seen doing. But you are not the fast one, you are just the passenger.

The aircraft that you are flying in, the machine that gives you powers to rise above the clouds in mere minutes is the true masterpiece. The masterpiece of military engineering. In this article, we will look into ten of the fastest military aircraft ever flown and see what they have in the trunk. Su-27SKM Number 10: Sukhoi Su-27 Flanker. Its top speed of 2.35 Mach brings it to the very edge of USSR craftmanship with a twin engine and the first fly-by-wire control system on a Russian jet ever. It was built for air superiority to counter the new American 3.5 gen fighters such as the F-15 Eagle.

It is armed with a 30 mm gun and 10 external pylons that can hold both Air-to-Air, heat-seeking, short and medium-range missiles. Due to all its accomplishments and popularity, it has very many different variants. Some of which are top-modern even today, 35 years after the first flight of the Flanker (1977).

Some of them are:

Sukhoi Su-30 Sukhoi Su-33 Sukhoi Su-34 Sukhoi Su-35 Sukhoi Su-37

And – the Sukhoi Su-27 Flanker was once available for passenger fun flights with MiGFlug! Read more here, Picture of an F-111 showing its variable sweep wing. Number 9: General Dynamics F-111 Aardvark. Number nine on this list is not a fighter but a tactical bomber capable of flying at Mach 2.5. It had, before its retirement in 1998, 9 hardpoints and 2 weapon bays, together with being able to deliver a payload of 14,300 kg of bombs, a nuclear bomb, air-to-air missiles or a 2000 round machine gun could be fitted. F-15C during Operation Noble Eagle Number 8 : McDonnell Douglas F-15 Eagle The F-15 has been claimed to be one of the most successful aircraft ever built and is still in service with the US Air Force. The Eagle’s twin-engine and thrust-to-weight ratio of almost 1:1 can propel the 18,000 kg aircraft to more than 2.5 times the speed of sound.

It was introduced in 1976 and will continue to be a part of the air force beyond 2025. There has almost 1200 F-15s built and it has been exported to among others Japan, Saudi Arabia and Israel. The current plan is to keep producing them until 2019. It was first designed as an air-superiority aircraft but later the F-15E Strike Eagle was built, an Air-to-Ground derivative.

The F-15 can load a variety of Sparrow, Sidewinder, 120-AMRAAM, drop bombs ( for instance Mark 84 or 82) or external fuel tanks on its 11 hardpoints. Together with its 20 mm M61A1 Vulcan gun, it is no surprise that this buster has over 100 confirmed aerial combat victories. MiG-31 flying over Russia Number 7: Mikoyan MiG-31 Foxbat With a top speed of Mach 2.83, the next aircraft on our list is the Mikoyan Gurevich-31 Foxhound (also this one was once available for tourist flights !). Due to its enormous twin-engine with a thrust of 2*152kN, it was able to fly at supersonic speeds at both high- and low altitudes.

One 23 millimetre gun with 260 rounds. Under fuselage:

4x R-33 Air-to-Air (heavy) or 6x R-37 Air-to-Air missiles.

On pylons:

Long or medium-range missiles, short-range IR missiles or a special medium-range Air-to-Air missile for high-speed targets.

The production ended in 1994 but is unknown exactly how many MiG-31 that were built but between 400-500 is said to be a qualified guess. The MiG-31 is still today in service with the Russian and Kazakhstan Air Forces. The MiG-31 is a derivative of the MiG-25 which can be read about further down (place 4) and in the link at the very end of the article. XB-70 Valkyrie (taking off) Number 6: XB-70 Valkyrie. The XB-70 Valkyrie was a unique aircraft with six engines which together could accelerate the 240,000-kilogram aircraft to a velocity of Mach 3. This speed resulted in the frame of the aircraft being heated up to as much as 330°C in some areas.

The extreme speed was needed for two reasons: 1: To accelerate away from Soviet interceptors and 2: To be able to escape the blast of the nuclear bombs that it was capable of dropping. The big size (weight) was needed to carry the fuel needed for the 6,900-kilometre flight into the Soviet Union and escape without refuelling and to house the 14 nuclear bombs that it was capable of carrying.

The aircraft had its first flight in 1964 and is now retired, only two were built. X-2 Starbuster together with its crew Number 5: Bell X-2 Starbuster. The Starbuster was an American research aircraft which had its first flight in 1955 and was retired in 1956. It was a continuation of the X-2 program and so Its area of investigation was to see how aircrafts behaved when flying at speeds higher than Mach 2.0.

It did, as can be understood, not carry any weapons and featured a back-swept wing which made it have little air-resistance and was by that able to achieve the stunning speed of Mach 3.196 in 1956. However soon after this speed was attained the pilot, Milburn G. Apt, made a sharp turn and the aircraft tumbled out of control.

He could not regain control of the aircraft and bailed out. Unfortunately, only the small parachute of the escape shuttle was opened and he hit the ground with too high speed. This fatal crash ended the Starbuster program. Mikoyan Gurevich 25PU Number 4: Mikoyan MiG-25 Foxbat. This jet was a Soviet machine built to intercept American aircraft during the cold war like the SR-71 and high- slow flying surveillance aircraft. Since it was built to intercept the SR-71 it was required to have an extreme speed, hence its Mach 3.2 top capability.

The Foxbat, unlike the Blackbird, featured 4 air-to-air missiles which made it an interceptor rather than a reconnaissance aircraft. It has never shot down a Blackbird but it has had many other combat missions which have been successful, for instance in the Iran-Iraq war. Over 1100 Foxbats were built between 1964 and 1984, however, today the use is limited, with its only users being Russia, Syria, Algeria and Turkmenistan.

For more information about this astonishing bird see the link at the bottom of the article. The MiG-25 was also the fastest plane ever offered for fun flights by MiGFlug – it was mainly used for Edge of Space flights, YF-12A, the first YF-12 Number 3: Lockheed YF-12. This jet was an American interceptor prototype with a top speed of Mach 3.35. It looked almost like the SR-71 Blackbird and featured three Air-to-Air missiles. The reason for it looking a lot like the SR-71 was because the SR-71 was based on the YF-12, and also because both of them had the same designer, the extremely famous Clarence “Kelly” Johnson. SR-71B (double cockpit) Number 2: Lockheed SR-71 Blackbird After its introduction in 1966 it has been used by both the USAF and NASA.32 Blackbirds were built, all used for reconnaissance and experimental research. It featured stealth technology but if it was, against all odds, spotted by enemy forces, it could outrun the interceptors or surface-to-air missiles that were fired at it, due to its fantastic speed.

1. The Blackbird was so fast that the air in front of it did not have time to escape, hence building up a huge pressure, and raised the temperature.
2. The temperature of the aircraft, which could reach several hundred degrees high, expanded the metal, hence it had to be built by too small pieces.
3. Because of this, the SR-71 actually leaked oil when standing still.

The Blackbird holds the record for manned, air-breathing aircraft, see here, A nice documentary about the SR-71 for those who love this plane as much as we do: The winner of our top 10 – the X-15! Number 1: North American X-15 This aircraft has the current world record for the fastest manned aircraft. Its maximum speed was Mach 6.70 (about 7,200 km/h) which it attained on the 3rd of October 1967 thanks to its pilot William J.

Pete” Knight. To be stable at these super high velocities, it had to feature a big wedge tail, however, the downside of this was at lower speeds the drag was extremely big from such a tail. Therefore a B-52 Stratofortress had to carry it up to an altitude of about 14,000 meters before dropping it at which it ignited its own engines.

Just imagine sitting in a rocket measuring only 15 m in length and then being dropped, must have been a truly magnificent feeling! The X-15 was used at such extreme speeds so that it did not use traditional ways to steer (using drag over a fin) but instead it used rocket thrusters! This made it possible to reach altitudes higher than 100 kilometres, which was one of its world records.

It was the first operational space plane. It got to a height of more than 100 km. It flew more than six times the speed of sound (Mach 6.70).

#### How fast is Mach 20 in flash?

While crunching the numbers to determine how much time he needed to build up the speed to travel in time, Barry calculated that he needed a 40,000 mile long runway to reach Mach 20 in two minutes. This meant that Barry would have had to run 15,345 mph (24,696 km/h).

#### Is there a speed faster than the speed of light?

Einstein’s special theory of relativity governs our understanding of both the flow of time and the speed at which objects can move. In special relativity, the speed of light is the ultimate speed limit to the universe. Nothing can travel faster than it. Every single moving object in the universe is constrained by that fundamental limit.

#### What can fly at Mach 20?

Mach 20 or Bust Target date 2025: A pilotless, Mach 20 Hypersonic Cruise Vehicle. Paul DiMare THE HYPERSONIC REALM is out there, just beyond our reach, above Mach 5. And so it has remained for decades. We’ve touched it briefly, even built vehicles—notably the X-15 and the space shuttle—capable of traveling at hypersonic speeds for short periods as they dive down from the edge of space.

1. Yet we always seem “10 years away” from a true aerospace plane that can cruise long distances through the atmosphere at many times the speed of sound without burning up.
2. The vision of hypersonic flight has seduced aviators, warriors, engineers, and presidents.
3. It was Ronald Reagan who in 1986 pitched the National Aero-Space Plane, the most ambitious hypersonic flight program ever conceived, a vehicle that was supposed to, “by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within two hours.” It never even came close.

And it took the field of hypersonic research years to recover from the letdown. After Reagan’s State of the Union speech, the media immediately branded the National Aero-Space Plane “the Orient Express.” The program was canceled in 1994, never having emerged from the research phase.

1. Many post-morta have been done on the NASP program,” says Mark Lewis, a professor of aeronautics at the University of Maryland and currently chief scientist for the U.S.
2. Air Force.
3. I think most people will agreethat they oversold the program.
4. They bit off much more than we could chew.
5. They were looking to get to Mach 25 with a single-stage-to-orbit the first time out of the hangar!” Looking back on NASP and the other flameouts, former Air Force historian Richard Hallion sees more than a string of failures, however.

“Hypersonics has had this image that it has been nothing but a huge rat hole for money,” he says. “But when you look at it, you can see the value of the research.” In fact, Hallion believes the many less-publicized successes since NASP have put hypersonic research on the verge of a real breakthrough.

• To make an historical analogy, this is like 1937 with the jet engine, which appeared in ’39,” he says.
• Or it’s like 1944 in supersonic, which we achieved in 1947.
• We’re right there.
• We’re starting to close theory and practice.
• We’re starting to see the reality of what we can achieve in terms of performance prediction and construction and materials.” In 2000, Hallion participated in a study for the Air Force Scientific Advisory Board, which concluded in its report, “Hypersonics could be the next great step forward in the transformation of the Air Force into a completely integrated aerospace force.” Partly as a result of the study, the Pentagon took the lead in U.S.

hypersonic research, though NASA is still involved. “My suspicion is that this is a technology that first and foremost is going to be a military technology, then a space access technology,” Lewis says. “Then maybe down the line it will have some civilian applications.” So forget about the Orient Express for now.

1. Think hypersonic weapons—Mach 6 missiles, more than six times as fast as today’s cruise missiles.
2. Launched from a distance, such weapons could destroy hardened targets with their high-speed impact alone.
3. The Pentagon wants the capability to reach any place on Earth—say a terrorist’s temporary hideout—within two hours.
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And unlike an intercontinental ballistic missile, a hypersonic missile could change course in flight or even abort its mission. That vision has spawned a mini-boom in hypersonic research—this time without the hype. Dozens of projects are under way worldwide, several of which will lead to test flights within the next few years.

• A trio of inter-related U.S.
• Military projects—HiFire, X-51A, and FALCON—are intended to solve different pieces of the hypersonic puzzle, from propulsion to aerodynamics to the peculiar physics of hypersonic flight.
• THE CURRENT BOOM began in the summer of 2002, with researchers at the University of Queensland in Australia launching a small hypersonic test vehicle on top of a sounding rocket.

For the first time, the experiment, called HyShot, proved that a key component of hypersonic propulsion, the scramjet, or supersonic combustion ramjet, could work in the atmosphere and not just in wind tunnels (see “Outback Scramjet,” Oct./Nov.2002).

By scooping oxygen from the atmosphere as they fly, scramjets liberate hypersonic vehicles from the need to carry heavy tanks of oxidizer for combustion. Since HyShot’s 2002 launch, international researchers have successfully flown air-breathing engines three times, reaching speeds just short of Mach 10.

In 2004, NASA took the next step by flying a scramjet engine that accelerated a 14-foot-long, surfboard-shaped unmanned vehicle called the X-43A to an astounding Mach 9.8 before the craft made a planned plunge into the Pacific Ocean (see “Debrief: Hyper-X,” June/July 2005).

1. The X-43 was a turning point, says Jim Pittman, principal investigator for hypersonics at NASA.
2. We learned two things: Scramjets really do work—you really can get positive thrust out of a scramjet—and you really can integrate a scramjet with a vehicle that you can fly and control.
3. And both of those things are huge.” As a hypersonics engineer at NASA for 30 years, Pittman has been through flush times and lean times.

“Living through it is frustrating,” he says. “It’s a cycle, and you just have to tough it out.” Pittman worked on the NASP as well as the X-43, which was part of a larger NASA program called Hyper-X. Ironically, around the time the X-43 succeeded, the agency’s aeronautics budget got slashed, one reason NASA now finds itself playing a supporting role to the Pentagon.

Which is not to say the space agency’s contributions are insignificant. This fall NASA will launch a small experiment on a commercial sounding rocket from NASA’s Wallops Flight Facility, off Virginia’s eastern shore. Called HyBoLT, for Hypersonic Boundary Layer Transition, the wedge-shaped payload should provide valuable data on the fundamental physics of high-Mach flight.

“When you hear the term ‘hypersonics,’ you should always think heat transfer,” Pittman says. “The single most important distinguishing feature of hypersonics is heat—the heat caused by the frictional forces of the air passing over the surfaces. In hypersonic flight the heat transfer is extremely large, and the higher the Mach number, the higher the heat transfer.” These problems are especially tricky in what’s called the boundary layer, the air that washes over the vehicle’s skin.

Though the boundary layer has been studied in wind tunnels and with computer modeling, how it behaves in actual hypersonic flight is still poorly understood. What is known is that as speed increases, the layer goes through a transition, eventually becoming fully turbulent. As that happens, temperatures double or triple.

And as the heat ratchets up, so does drag, which can radically affect flight characteristics. “We need to better understand it,” says Pittman. “It’s the most critical thing in hypersonics.” The HyBoLT test article, which looks like the flat tip of a screwdriver, will be launched on its suborbital rocket to an altitude of 250 miles, while instruments record temperatures and pressures on different parts of the surface.

It’s a modest experiment—the kind of basic data collection that supports the sexier test flight programs. Not far from Pittman’s office at NASA’s Langley Research Center in Virginia, testing is under way for one of those high-profile programs—the X-51A scramjet demonstrator, a \$240 million collaboration between the Defense Advanced Research Projects Agency (DARPA) and the Air Force.

A scramjet engine for the vehicle has been fired dozens of times at Langley’s 8-Foot High Temperature Tunnel. With four test flights over the Pacific Ocean slated to begin in 2009, the X-51A will ultimately attempt record-breaking engine burns lasting five minutes, which should propel the craft to about Mach 7.

1. Like the X-43, the X-51A is a wave rider.
2. After being boosted to high altitude, the vehicle will light its engine and surf its own shock wave, compressing the air in front of it and lowering drag.
3. Though the immediate goal is to flight test a propulsion system for a superfast missile, the project received the X-plane designation in recognition of its potential to advance the field of hypersonics generally.

For Mark Lewis, the X-51A is all about the scramjet. “We want to see a scramjet engine work for more than 10 or 11 seconds,” he says, referring to the burn times of the two Hyper-X flights. Engine burns of several minutes would demonstrate to skeptics that long-duration scramjet-propelled flight is feasible.

1. Skeptics might be forgiven their doubts.
2. Achieving combustion in an air-breathing engine moving at thousands of miles per hour has been compared to keeping a match lit in a hurricane.
3. Hyper-X protected the precious flame in its combustion chamber behind carefully focused shock waves, but only for seconds.

The X-51A engine will have to run at least 30 times longer. To cover their bets, DARPA and the Air Force have two companies, Pratt & Whitney Rocketdyne and ATK, developing two kinds of hypersonic engines. One major difference from Hyper-X is that the X-51A will burn conventional jet fuel instead of the liquid hydrogen that very-high-performance rocket and scramjet engines normally use.

It won’t be the first scramjet to do so: In December 2005, a DARPA-Navy project called HyFly launched a missile perched on a booster rocket from Wallops Island in Virginia. The missile’s air-breathing engine, which ran on JP-10 aviation fuel, flew for more than 15 seconds under scramjet power. Pratt & Whitney’s engine is called the X-1.

When flying at hypersonic speeds, JP-7 aviation fuel rushes into the X-1’s three-foot-long combustion chamber at 3,300 feet per second. A closed-loop system cycles the fuel around the engine, using it as coolant to draw heat and pressure off the combustion chamber.

• In the process, the extreme heat—more than 3,000 degrees Fahrenheit—”cracks” the fuel’s molecular structure.
• The cracking shortens the molecules and allows the fuel to burn more quickly, which is imperative.
• If the fuel doesn’t ignite in the microsecond in which it flows through the chamber, it will spew out uselessly, producing zero thrust—and a very fast falling object.

Over the past year, the X-1 engine has worked as advertised in Langley’s test chamber, culminating in a 50-second-plus, simulated X-51A flight at more than Mach 5 last April. In less than two years, the X-51A will have a chance to prove itself in the atmosphere.

1. Each test flight will begin with a B-52 taking off from Point Mugu, California.
2. The airplane will carry the 14-foot vehicle up to 49,500 feet over the Pacific, where it will be released attached to a booster derived from an Army missile.
3. The booster will get the demonstrator to over Mach 4, whereupon the scramjet engine will fire to propel it to full speed.

With the X-51A attempting to prove that hydrocarbon scramjets can propel hypersonic missiles, it’s up to other projects to sort out how to achieve higher Mach numbers. For some of those answers, Lewis and the Air Force made a long flight down under to work with the Australians who came up with HyShot.

EVEN AT 500 MPH, it takes a long, long time to reach Australia. “Just eight movies and you’re there,” Australians joke. The country’s remoteness may account for its fascination with hypersonic flight; someday the travel time from London to Sydney may come down to one movie. The Australian hypersonics program has been making steady progress for a decade, but it really took off in 2002, when HyShot fired the world’s first scramjet engine in flight.

Building on that accomplishment, the Australian Department of Defense joined its U.S. counterpart, along with NASA, Boeing, and other partners, in an innovative international project called HiFire, for Hypersonic Flight International Research Experimentation.

1. Funded with \$54 million, HiFire includes a series of experiments and at least 10 test flights to be conducted over the next six years.
2. Mark Lewis, who signed the agreement for the United States last November, says that the project complements the X-51A and other U.S.
3. Hypersonics efforts.
4. In HiFire, we’re looking at very fundamental science: all the problems we think we would anticipate in hypersonic flight.” Next year the HyShot team will test a new free-flying vehicle as part of the HiFire program (earlier HyShots stayed attached to their booster rockets).

One research goal is to try different shapes for scramjet engines in the search for greater efficiency, starting with the air inlet. Instead of a simple rectangular slot, shaped like the front of a Dustbuster vacuum cleaner, the inlet for the REST (rectangular-to-elliptical shape transition) engine is three-dimensional and more complex.

The opening is still generally rectangular, but it includes faces that slant in toward the combustion chamber. Michael Smart, an associate professor in the HyShot group at the University of Queensland, explains: “The reason these 3-D inlets are more efficient is that the air is compressed by all surfaces of the inlet.

A 2-D inlet only compresses the air in one plane: The side walls create drag, but don’t do any compression.” The outer rectangular shape of the inlet offers an advantage: Stacking engines side by side is easier. But inside the vehicle, the inlet connects to an elliptical combustion chamber.

• Joined together, the pieces look like the different sections of a car’s exhaust system.
• This is a departure from the X-43A, which had a rectangular combustion chamber.
• Elliptical combustors are better, says Smart, because “round shapes are inherently stronger than rectangles.
• This leads to thinner walls and less weight.

They have less surface area for the same amount of air flow through the engine. Less surface means less drag, less heating, and less weight.” And since energy tends to ebb in rectangular combustors’ corners, getting rid of the corners can increase overall thrust.

• HiFire flights will launch from southern Australia’s Woomera test range, the largest testing grounds in the world.
• The size of the range, its isolation, and the chance to fly frequently are real benefits, says Lewis.
• The costs are low enough that if the things break, if they don’t work, if they crash into the Australian Outback, we’ll keep the program going.

We’re not going to give up because of one failure.” It’s a small-is-beautiful approach. “When you go to really, really expensive demonstrators, suddenly you’re so terrified of things not working or not flying that you paralyze your flight test program,” he says.

1. And that’s one of the things we’re trying to avoid.” Of the three major hypersonic programs under way, the most ambitious is FALCON.
2. HiFire’s short, up-and-down flights will reach Mach 10 or so.
3. FALCON aims to fly up to Mach 20 over a distance of thousands of miles.
4. Led by DARPA, FALCON is short for Force Application and Launch from CONUS (continental United States).

As the name implies, FALCON was conceived as both a potential weapons system with global reach and a capability to launch military space payloads as a quick response. The distant goal of the program is to develop, by 2025, an unmanned, reusable Hypersonic Cruise Vehicle (HCV) approximately the size and weight of a B-52.

• Taking off and landing like an airplane, the HCV would be able to deliver a 12,000-pound payload 9,000 miles from the continental United States within two hours.
• It’s the Orient Express turned into a bomber, without the pilot or passengers.
• HCV is the vision vehicle,” says Steven Walker, who manages DARPA projects related to hypersonic flight, including FALCON.

A four-year veteran of the agency with degrees in aerospace engineering, he knows he’s working against physics as well as skepticism in the military ranks. Many Pentagon strategists would rather extend the capability of conventional missiles like Tridents than pursue a notoriously elusive and costly technology.

“We need to fly some hypersonic vehicles—first the expendables, then the reusables—in order to prove to decision makers that this isn’t just a dream,” he says. “We won’t overcome the skepticism until we see some hypersonic vehicles flying.” Walker and DARPA, working with the Air Force, NASA, and Lockheed Martin, hope to commence the airshow in December 2008, launching a series of small, expendable Hypersonic Test Vehicles (HTVs) to demonstrate sustained flight between Mach 10 and 20.

One long-standing problem FALCON hopes to solve is how to build an aeroshell that won’t self-destruct in long-duration, high-temperature flight. Easier said than done. Before it had even been assembled, let alone flown, the first test vehicle, the HTV-1, hit a rough patch—literally a bunch of bubbles.

The subcontractor for FALCON’s aeroshell was laying up the carbon-carbon prototype material in small sections to provide samples for aerodynamic and thermal testing. Each piece was made of six or seven layers, and as the technicians applied each layer, the material would stretch and pull the layer beneath it, creating voids and air pockets, particularly around curves.

It was a potential showstopper. In flight, intense heat would cause the bubbles to burst, destroying the airframe. With advice from experts, Walker and the team made a tough decision: abandon the highly curved HTV-1 design and go straight to HTV-2. That meant the first vehicle would not fly as planned this fall.

“When you’re dealing on the edge of what’s been done before, it’s never going to be perfect the first time,” says Walker, trying to make the best of the schedule slip. “Dash-2” is now being assembled by Lockheed Martin’s legendary Skunk Works in Palmdale, California. Like Dash-1, HTV-2 is an expendable vehicle, but with a narrower delta shape, a dagger tip, and sharper leading edges for sleeker aerodynamics.

With fewer curves, it should be easier to construct. In December 2008, the 10-foot-long HTV-2 will launch from Vandenberg Air Force Base in California. As a boost/glide vehicle, it carries no power of its own, but will be accelerated to over Mach 10 on top of a rocket booster.

1. On the downslope, the vehicle will glide at Mach 20 over the 4,800-mile stretch between California and Kwajalein Atoll in the Marshall Islands, home to the Ronald Reagan Ballistic Missile Defense Test Site.
2. As it pushes up through the upper atmosphere and begins its glide path down, Dash-2 will generate more than 3,000 degrees of heat, burning off, or ablating, layers of carbon-carbon from its aeroshell.

FALCON engineers will study the test data carefully to see how the shape changes affect the aircraft’s aerodynamics. The second flight, in June 2009, will be a more circuitous course, with the craft attempting a sharper angle of attack while performing pitch and yaw maneuvers.

The last of the proposed FALCON test vehicles is HTV-3, which would add vertical and horizontal stabilizers for maneuvers at lower, but more sustained, speeds of around Mach 10. Originally scheduled to fly in 2010 as a recoverable boost/glide vehicle, Dash-3 may instead fly two years later in a different mode—taking off and landing like an airplane, under its own power, using an engine developed by DARPA under another project, called FaCET, for FALCON Combined-cycle Engine Technology.

The FaCET engine combines a turbojet (to get up to around Mach 4) with a hydrogen-fueled scramjet (to reach Mach 10). The turbojet is itself a challenge; the fastest turbojet yet flown, the J58 used on the SR-71 Blackbird, could only manage Mach 3.2. Like the Australian engine, FaCET has a fancy 3-D air inlet—a good example of how the different hypersonic research programs feed one another.

1. If successful, the flights would prove by 2012 that a reusable thermal protection system works in actual hypersonic flight.
2. And that would be a big step toward building Walker’s hypersonic-cruise “vision vehicle.” “If the country wants to put a real operational system together, we’ll be in a position to do that in 2020,” he says.

“If we don’t do these demonstrations now, then we’ll never get there.” While there’s less hype associated with the current hypersonic boom, there’s still plenty of hypothetical. One wild card is politics—how this technology will play in the policy arena.

1. Richard Hallion is certain that missiles capable of flying at speeds between Mach 5 and Mach 7 will transform global warfare.
2. I would not be surprised at all to see somebody in the next decade unveil a hypersonic weapon that they are able to put into service,” he says.
3. Though he declines to say which somebody he has in mind, many nations other than the United States—allies, foes, and neutrals—are known to be working on the problem.

The first weapons, Hallion says, are likely to be small missiles, like the X-51A, fitted with efficient scramjets, able to be fired from mobile transports on land, sea, or air. He further predicts that hypersonic technology will become “common currency,” like the jet engine.

## Is the speed of light faster than Mach 1?

The speed of sound in air is 343 m/s (Mach 1) the speed of light in atmosphere approximates at 3×10^8 m/s. So to answer your question the speed of light is approximately Mach 874,635.6.