Superfast Drone

The drone, which resembled a rocket, flew 10 miles (16 km) at Mach 0.9 — over 680 miles per hour — using 80% of the engine's available thrust. This image is purely illustrative. (Image credit: Alexyz3d/Getty Images)




Venus Aerospace has completed the inaugural test flight of a drone fitted with its "rotating detonation rocket engine" (RDRE) — accelerating it to just under the speed of sound. The company wants to one day build superfast commercial jets using this new type of engine.


In the test flight, conducted Feb. 24, the company flew the drone, which is 8 feet (2.4 meters) long and weighs 300 pounds (136 kilograms) to an altitude of 12,000 ft (3658 m) by an Aero L-29 Delfín plane, before it was deployed and the RDRE was activated, company representatives said in a statement.


The drone flew 10 miles (16 km) at Mach 0.9 — over 680 miles per hour — using 80% of the RDRE’s available thrust. The successful flight proved the viability of RDRE and the associated onboard flight systems. Three weeks earlier, Venus Aerospace demonstrated the viability of its RDRE technology with a long-duration test burn — during which engineers showed their engine worked for the duration of this test flight.  READ MORE...

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.

Speed of Light and Sound
This isn’t something like the speed of sound. Early scientists wondered if we could ever go faster than that speed, not because of some fundamental rule of the universe, but because we didn’t know if our engineering and materials science capabilities could withstand the extreme turbulence generated by moving at such speeds. But everyday objects already surpass the speed of sound. For example, the crack of a whip is caused by the tip creating a sonic boom as it travels faster than the sound speed.

The problem with trying to surpass the speed of light is that as you go faster, the more kinetic energy you have. But relativity tells us that energy is the same as mass, so the faster you go the more massive you become (and yes, this means that a moving baseball has more mass than one standing still, but that’s a tiny effect).

As you approach the speed of light, your mass balloons up to infinity. The closer you get to the speed of light, the more out of control your mass becomes. With higher masses, you must push yourself harder to accelerate, and you quickly find yourself in a position where it would take an infinite amount of energy to overcome light speed.

Exploring Light Speed
This isn’t just a matter of clever engineering or figuring out some trick – this is built into the fabric of the universe.

That said, there are proposals out there for designing specialized devices that could supposedly overcome this limit without outright breaking relativity. These concepts work because special relativity is a law of local physics: It tells you that you can never measure nearby motion going faster than light speed.  READ MORE...

A New Hypersonic Plane

Venus Aerospace is building a hypersonic aircraft that can carry about a dozen passengers, traveling at Mach 9, nine times the speed of sound. The Stargazer, which measures 150 feet long by 100 feet wide, will travel between two cities in the world, says the Houston-based company, by flying 6,905 mph at an altitude of 170,000 feet.

Hypersonic is defined as five times the speed of sound. By comparison, the last commercial supersonic jet, the Concorde, traveled at Mach 2, or about, 1,535 mph. The fastest aircraft ever built, Lockheed’s SR-71 “Blackbird,” traveled at Mach 3.2 (2,455 mph).

Venus co-founder and CTO Andrew Duggleby plans to move Stargazer from science fiction to reality with a rotating-detonation engine that spins at 20,000 rotations per second. “Rotating detonation means the supersonic combustion happens continuously inside the engine and our video shows the detonation wave moving around the engine at supersonic speeds,” noted the company after its recent successful test of a prototype at its Spaceport Houston headquarters.

The Stargazer is one of several hypersonic aircraft trying to get off the ground.

Courtesy Venus Aerospace

The rotating-detonation concept, which burns 20 percent less fuel than a conventional engine, is being promoted by the US Navy. This technology has been successfully tested before. But the Venus test was the first time using a room-temperature storable propellant, which will make the engine more viable for aircraft. “We now have both the technical knowledge and engineering to fully advance into next steps of development and flight testing,” said Duggleby.

The 150,000-lb. Stargazer will take off with conventional jet engines, but then transition to rockets once it reaches altitude. The route it will fly is not technically on the edge of space, or the Karman line, which is 100 kilometers above the Earth’s surface. But it will be high enough to see the planet’s curve and the blackness of space.

“This represents a key advancement towards real flying systems, both for defense applications and ultimately commercial high-speed travel,” said Jim Bridenstine, former NASA administrator and US Congressman, following the test.  READ MORE...

Speed of Sound on Mars

Scientists have confirmed the speed of sound on Mars, using equipment on the Perseverance rover to study the red planet's atmosphere, which is very different to Earth's.

What they discovered could have some strange consequences for communication between future Martians.

The findings suggest that trying to talk in Mars' atmosphere might produce a weird effect, since higher-pitched sound seems to travel faster than bass notes. Not that we'd try, since Mars' atmosphere is unbreathable, but it's certainly fun to think about!

From a science perspective, the findings, announced at the 53rd Lunar and Planetary Science Conference by planetary scientist Baptiste Chide of the Los Alamos National Laboratory, reveal high temperature fluctuations at the surface of Mars that warrant further investigation.

The speed of sound is not a universal constant. It can change, depending on the density and temperature of the medium through which it travels; the denser the medium, the faster it goes.

That's why sound travels about 343 meters (1,125 feet) per second in our atmosphere at 20 degrees Celsius, but also at 1,480 meters per second in water, and at 5,100 meters per second in steel.

Mars' atmosphere is a lot more tenuous than Earth's, around 0.020 kg/m3, compared to about 1.2 kg/m3 for Earth. That alone means that sound would propagate differently on the red planet.

But the layer of the atmosphere just above the surface, known as the Planetary Boundary Layer, has added complications: During the day, the warming of the surface generates convective updrafts that create strong turbulence.  READ MORE...