USAF Hypersonic Scramjet Successfully Scrams 201
cold fjord writes "It looks like another milestone for hypersonic flight has been reached. From the story: 'The final flight of the X-51A Waverider test program has accomplished a breakthrough in the development of flight reaching Mach 5.1 over the Pacific Ocean . . ."It was a full mission success," said Charlie Brink, X-51A program manager for the Air Force Research Laboratory Aerospace Systems Directorate. The cruiser traveled over 230 nautical miles in just over six minutes over the Point Mugu Naval Air Warfare Center Sea Range. It was the longest of the four X-51A test flights and the longest air-breathing hypersonic flight ever. . . This was the last of four test vehicles originally conceived when the $300 million technology demonstration program began in 2004. The program objective was to prove the viability of air-breathing, high-speed scramjet propulsion. The X-51A is unique primarily due to its use of a hydrocarbon fuel in its supersonic combustion ramjet, or Scramjet, engine. ... The use of logistically supportable hydrocarbon fuel is widely considered vital for the practical application of hypersonic flight.'"
longest flight.... (Score:5, Informative)
A short definition for all those non-native speakers who wonder - like me - how 6 minutes of flight are more than hours of flight by a Concorde:
Supersonic: Above speed of sound but only up to Mach 5
Hypersonic: Above Mach 5
The fact that both the latin Super [latinwordlist.com] and the greek Hyper [answers.com] translate into the same word does not really help the distinction.
Re:Goodness me! Was that a Whooosh? (Score:5, Informative)
We haven't had a public breakthrough weapons technology as good as megaton nukes, since the 60's.
I don't think that is correct. The impact of precision guided munitions has already had a huge impact, and it continues to grow. The following except refers to events around Operation Desert Storm in 1992. At that time precision guided munitions were largely bombs and missiles, and a few expensive anti-tank artillery rounds. Now that capability is finding its way to more mundane artillery and mortars as well, not to mention much smaller missiles. The devices are becoming smaller, lighter, more precise, easier to use, and cheaper, so there will be a lot more of then in the future. A large strike by precision weapons could easily reverse the tide of battle in a way that nothing short of a nuclear weapon could in the past. Compared to nukes there are few drawbacks and many substantial advantages, such as not contaminating the battlefield and the fact that their use doesn't really have any of the political problem that nuclear weapons have.
IMPACT OF PRECISION WEAPONS ON AIR COMBAT OPERATIONS [af.mil]
We are writing a new and exciting chapter on air power--a chapter made possible in part by precision guided munitions (PGM). Air power advocates have long dreamed of a day when the weapon, platform, and willingness to use them properly would come together to make air power a decisive force. Today, those dreams are reality. One need only look back to our raids on Schweinfurt, Germany, in World War II to see how dramatically precision weapons have enhanced our capabilities over the last 50 years. Two raids of 300 B-17 bombers could not achieve with 3,000 bombs what two F-117s can do with only four. Precision weapons have truly given a new meaning to the term mass.
To shut down an industry in World War II, we were forced to target entire complexes because of the inaccuracy of our weapons; today we would need to hit only a couple of key buildings. What we historically achieved with volume we now can accomplish with precision. After all, the objective has never been to see how many bombs we could drop, but to produce results.
Precision weapons may also constitute a revolution in mobility. Of the 85,000 tons of bombs used in the Gulf War, only 8,000 tons (less than 10 percent) were PGMs, yet they accounted for nearly 75 percent of the damage. If we had wanted to, we could have airlifted all of our PGMs with just five C-5s or nine C-141s a day.2 . . . more [af.mil]
To circle the globe (Score:4, Informative)
The average radius of the Earth is 3,959 miles (6,374 kilometers).
The equitorial diameter of the Earth (distance from one side of the Earth to the other at the equator) is about 7,926 miles.
The ratio of the circumference to the diameter of a circle (circumference/diameter)
is written as the symbol pi.
Pi is approximately 3.141592.
3.14159265
3.1415926535
Therefore, to determine the circumference from the diameter given above:
equitorial diameter x 3.141592 = equitorial circumference
| |
7,926 x 3.141592 = 24,900
| |
The earth has a circumference of approximately 24,900 miles.
More precisely the circumference of the earth
at the equator is 24,902 mi / 40,076 km.
Source:http://lyberty.com/encyc/articles/earth.html
5.1Mach = 1.7355km/s
Source: http://www.metric-conversions.org/speed/mach-to-kilometers-per-second.htm [metric-conversions.org]
It depends on what type of plane you are flying in and what air routes you plan to take. The typical duration is usually 2 days to 4 days.
For instance, an F-16 could theoretically circumspect the world in slightly less than 78 hours. But that's only possible if all the refuellings are conducted as in-flight refuellings, via airborne tankers. With luck and some good currents around, it might shave 2 hrs or so off the total time needed. But then again, unless you can stay awake for 3 days without sleep, its damn near impossible to do that.
For a civilian airliner like a Boeing 747 or an Airbus, it would take around the same amount of time, largely due to the need to bring it down to an airstrip for refuelling. But because of its huge internal fuel capacity, it could remain airborne far longer than an F-16.
To help you with your essay, I'm going to list the conditions required to accomplish this in a realistic manner:
1) Type of aircraft and its configuration
A civilian airliner jet (like those 2 mention earlier) typically have intercontinental ranges in excess of 3,000km. Also, they are capable of carrying huge quantities of internal fuel. Assuming you take a Boeing 747, removed all the seats in the passenger compartment and turn them, along with the cargo area into fuel storage, that range will be increased dramatically, from 3,000km to 7,000km.
Taking it further, by adding a refuelling receptor to the jet itself, similar to those used by the Air Force for its planes like the C-17 Globemaster III, the maximum range effectively becomes unlimited.
2) The human factor
Flight operations are no trivial task. While computers and automated intelligent system have made it easier for modern day pilots, the task of flying itself is still a tiring activity. Pilots need to maintain vigilance not only over the flight systems on the aircraft but also need to keep an eye out for weather conditions. Although the availability of long range radar and weather satellites have made detection of distance storms easier and earlier, its ultimately a human that takes actions to avoid it.
Maintaining wakefulness is a mentally exhausting affair, especially when is also an extremely dull affair, since an un-occupied mind is a bored mind, which translate into mental lethargy, which is also sleepiness. A human being usually loses his ability to react quickly after 12 hours of continuous flying. After 18 hours, that ability falls by 10% for every 2 hours after that.
3) Flight profile and weather conditions
The reason why airliner jets can sustain long range flights is because it cruises along at high altitudes. This is one of the aspects of aerodynamics, the higher you fly, the less fuel you burn, thus allow maximum milage per pound of fuel.
Air currents can aid and also hinders an aircraft's performance. With the proper air currents available (dependant on the time of
Re:longest flight.... (Score:5, Informative)
It's the first success with a radically new regime of flight surface/engine. The SR-71 was the evolution of the Wright Flier pushed to its very limit (well, the ramjet represents a slight break, but not a tremendous leap).
Once you start getting a long way over the speed of sound combustion cannot propagate fast enough to push you along. Your airfoils don't work the same at supersonic speeds either.
The principles on which slower than air flight works don't really apply over about mach 3. A scramjet produces lift in a different way, the engine is based on different principles. Your engine is this bizarre thing which is formed partly by the airflow around the aircraft and much of the useful combustion/fuel heating happens on the outside in order to stop your intake melting.
A working scramjet allows evolution from that platform (ie. now that there is one to modify, you can tweak it to get the ignition speed down, the thrust up, and so on). They're also the only other option to rockets that can provide a meaningful amount of energy to a spacecraft (learn the rocket equation, then realise that your propellant in an air breathing engine comes pretty close to free to understand why this could make a big difference).
Re:To circle the globe (Score:3, Informative)
> 5.1Mach = 1.7355km/s
Summary: so it's a little over a mile a second, 24500/3600 = ~6.8 hours.
Applications? (Score:5, Informative)
A fascinating development, but I worry that the applications are limited to delivering bombs. Since the engine doesn't even function below hypersonic speeds, a plane and rocket are necessary to even launch them, and that naturally limits the size. As such, I don't particularly see the development as a positive thing in the near term, nor does it make me feel any better that the US military is the one doing it.
A hybrid jet/rocket engine like the SABRE [wikipedia.org] is far more attractive, as it can deliver Skylon [wikipedia.org] from runway to space, and is efficient throughout. The remarkable enabling technology is a precooler which cools incoming air from 1000C to -150C in milliseconds, and has already been successfully demonstrated.
Furthermore, there is a also a variant optimized for atmospheric flight called Scimitar [wikipedia.org], which uses the precooler with a high-bypass turbofan engine, giving it good efficiency and subsonic exhaust velocities at low speeds. This flexibility and broad efficiency allow the A2 [wikipedia.org] to operate over land as well, overcoming the limitations of the Concorde. It has the potential to make commercial hypersonic flight ubiquitous.
Re:Goodness me! Was that a Whooosh? (Score:4, Informative)
The middle east has the same problem china has: The US Navy and lots of deep, deep water inbetween us and their hatred.
Mass producing american goods != coming up with new ones of their own. I don't think they're still fighting with bamboo sticks. I think they're fighting with Su-30 aircraft with a range of 3k miles and the j-20 with a range of 1,400 miles. They have a single aircraft carrier, but only a handful of either have a navallanding package. Their main battle tank was developed during the cold war and probably does not have active armor as all pictures of them have been shown with blocks of laminate armor (it's larger than active armor) and relies on lazer dazzlers to block incoming mistles, but cannot stop heat seaking, GPS guided, or visually guided weapons. It's a joke, but they have lots and lots of them.
Their infantry fights with the type 88 LMG, Type 81 (AK Clone), and QBZ-95 bullpup. The first two are great guns, the last is crap according to all reports I've ever seen. Either way, they have no soldiers with experience using them while people are shooting back and no way to get those soldiers to our shores.
They can launch mistles at us, but we can drop many of them into that large, wet ocean I've previously mentioned. Those that do make it to the US would be retaliated against with our own mistles which the chinese have no way of shooting down. They can launch chemical and nuclear weapons, but as Pearl Harbor and 9/11 both showed the world, when you attack the US, the US attacks back at a much higher ratio. We have the equipment and the men who are willing to use them. We have armies of volunteer citizen soldiers instead of conscripted subjects. Citizens fight much harder than subjects and run away far less often.
I sith "back just playing these guys off" after a long carrer sitting in wet damn holes with a rifle in my hand. I'm a nerd and slashdotter as a hobby, war has always been my profession. When I speak of war, it's as an expert, not an armchair general.
Re:longest flight.... (Score:5, Informative)
Now, ~50 years later, a missile flies at Mach 5.1 for 6 minutes. That is a 50% increase in speed in ~50 years. This is hardly the tremendous breakthrough that is claimed.
What kind of comparison is that?
The technology behind the Blackbird topped out at about the speed you mention. The technology that has made this scramjet possible is just getting started at mach 5.1.
If that doesn't convince you, bear in mind that at this level even the difference between mach 5.0 and 5.1 is rather considerable, much like the difference in required engine power between 300kph and 350kph.
A milestone! A breakthrough! (Score:3, Informative)
Ease off the hyperbole.
1991: The first recorded successful scramjet test, when a modified Russian SAM was used as a booster for an engine which achieved supersonic combustion for 5 seconds.
1992: Another similar test, with French funding, pushed that out to 15 seconds.
2002: HySHot demonstrated the first controlled flight with supersonic combustion ...
2013: A milestone! A breakthrough!
Re:A milestone! A breakthrough! (Score:5, Informative)
Re:Goodness me! Was that a Whooosh? (Score:5, Informative)
Four things. First, Professor Ray Stalker is indeed a credit to Australia and I look forward to his continued success.
Second, the article is about the successful test of a US Air Force test vehicle. They are entitled to celebrate their success.
Third, your history is a bit off.
Scramjets integrate air and space [aip.org]
Scramjets have a long and active development history in the United States. On the basis of theoretical studies started in the 1940s, the U.S. Air Force, Navy, and NASA began developing scramjet engines in the late 1950s. Since then, many hydrogenand hydrocarbon-fueled engine programs have helped scramjet technology evolve to its current state. The most influential of these efforts was NASA’s National Aerospace Plane (NASP) program, established in 1986 to develop a vehicle with speed greater than Mach 15 and horizontal takeoff and landing capabilities. The program ended in 1993, but the original NASP engine design, significantly modified by NASA, provided the foundation for the power plant used during the X-43A’s recent flight.
Fourth, you diminish yourself when you associate yourself with Alex Belits' bile filled, historically illiterate, diatribes.
Re:Goodness me! Was that a Whooosh? (Score:4, Informative)
This whole thread ^ is the reason why we have Governments. If regular people were left in charge, the entire world would be choking to death from a Nuclear Winter.