The X-43: The Speed Record Set by an Unmanned Aircraft
April 7, 2004 – Completed April 8, 2004
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Added on July 18, 2007
The entire press has picked up the story. Americans have just broken a speed record with an unmanned vehicle, carried to altitude beneath the wing of a B-52 and then launched at Mach 7 by a large solid-fuel booster. At this speed (8,000 km/h), the vehicle reportedly maintained its velocity for a dozen seconds, propelled by its "scramjet"—a supersonic ramjet engine.
Everyone believes it. Thus, "Americans are envisioning a future, albeit distant, in the realm of hypersonics. The figures are announced: 10,000 km/h, a machine capable of circling the Earth at 60–80 km altitude."
Yet I still have a question. The SR-71, the famous US spy plane flying at Mach 3 and a bit more, at 3,500 km/h, has been in the museum in Seattle since 1991. That’s thirteen years. What do the Americans have to replace it?
In general, when something is retired, it’s because we have something better. Nothing replaces the airplane. The satellite performs only a ballistic flight. It’s expensive to launch. The rocket isn’t reusable. You can’t say, “Could you please make a detour here, fly over this?” The satellite follows a circular orbit. We’re forced to make choices. Moreover, it can’t descend below a certain altitude, otherwise the air slows it down. Yet, if we believe the Americans, they no longer have a spy plane. If they did, it would have taken over from the Blackbird SR-71. How did the latter work? With turbojets. It had air intakes equipped with conical spikes where shock waves attach, compressing and heating the air. Compression is desirable—combustion couldn’t occur in air too rarefied. That’s why, at the inlet of a turbojet, there’s an axial compressor with blades, which then directs the compressed air into combustion chambers.
But beyond Mach 3, the shock wave produces air downstream that’s too hot to be sent to turbine blades. Those blades would vaporize. Between Mach 3 and Mach 5 lies the ramjet. You simply remove the turbine—the shock wave alone provides sufficient compression. You can arrange for the flow downstream of the shock to be subsonic. But for higher Mach numbers, this becomes problematic again. We then enter the realm of the scramjet, a ramjet where combustion occurs in supersonic flow. Very difficult to operate. Not flexible at all. But it can work between Mach 5 and Mach 7. There are Franco-Russian studies where vehicles with rotational symmetry are tested, brought to high speeds by surface-to-air Sam 7 rockets, I believe. In this configuration, the fuel is liquid hydrogen, which is circulated beforehand through the leading edges of the vehicle.
Beyond Mach 7 lies the "heat barrier."
Let’s summarize. If the Americans are truly at the stage claimed—testing a 2.5-meter model for ten seconds—then a piloted vehicle will emerge in 10 to 20 years. For 15–20 years, while kids play with the Blackbird at the Seattle museum, the Americans will remain "with nothing." Just like us with our military nuclear program, without tests since 1996. That’s already eight years. It seems we’ll manage this with a supercomputer and a laser simulator.
Ah, if you read this month’s Air et Cosmos, you’ll see that Americans are considering using MHD (magnetohydrodynamics) to ease atmospheric reentries and even pilot warheads. We’re living in a fantastic era. We’re informed of progress day by day. Secrecy is passé. We’re shown systems at the pre-study stage. In the past, we were kept in the dark about the existence of the U-2 (until Gary Powers was shot down over the Soviet Union), the F-117A, and the Blackbird. But today, everything is known. We’re kept informed. It’s nice.
Iwrote a book expressing my thoughts on all this. There has been no debate anywhere. Aside from scientifically incompetent ufologists like Gildas Bourdais, my writings have been ignored. I even read, regarding the famous photo taken over 20 years ago at Groom Lake, showing a dotted trail, that an "ONERA expert" (National Office for Aerospace Studies and Research) concluded it was pulsed combustion, noting that such a regime would be extremely uncomfortable for any passengers or pilots. I recall I offered a different explanation in my book: that the semi-guided nozzle of the vehicle wasn’t operating at its designed altitude, creating a classic standing wave pattern—alternating nodes and antinodes—in the exhaust jet, with shock waves.
My mind is made up. I’ve published files on my website about the curiosities of the B-2. In truth, I’m completely off the mark. For long-range bombing, subsonic flight with multiple in-flight refuelings is the future. For reconnaissance and stealth, I predict a strong comeback for the hot air balloon. On the naval front, the ideal is sailing ships. It’s obvious—the wood is completely stealthy. We don’t go fast, but we’re totally invisible to radar.
It’s pointless to fight against the dominant idea. Besides, I’m not fighting anymore. In astrophysics, long live dark matter, dark energy, inflation, and the time before the Big Bang. It seems that in labs, people are equipping themselves with extremely fine and short needles (Planck length: 10⁻³³ cm) to knit branes for winter, of course using superstrings. Since the future appears so problematic, I thought, “Let’s turn our attention to the past.” Hence my interest in ancient Egyptian ships, the drifting rafts of ancient Peruvians, and a few other things not particularly bug-like. In about a month, I expect we’ll be able to proceed with tests of the “Coelacanth,” of course subsonic. It was supposed to happen in February, but we had ten centimeters and a meter of snow. Now the lake is dry. We’ll find another one.
A reader sent me a few photos taken at an American site, showing the X-43 from various angles. The comments are his.
Note the two flashing lights on the top of the stainless steel plate, used to signal turns.
In this close-up view, the headlights or side lights (port and starboard) are clearer.
In fact, when searching for other images, we see that these large protrusions made of lightweight alloy aren’t the aircraft’s turn signals. They serve at least one function. The flats they bear (and which are oriented differently on each side) indicate that these parts are screwed onto the structure. These components also have conical machining features (with a similar mechanism underneath) that allow the vehicle to be clamped securely in a fixture for handling and transportation.
The following close-up shows technicians manipulating the vehicle, firmly secured in a...