One company is working with smart partners to start test flights of kinder and gentler supersonic planes as early as next year.
So what does it mean that Boom Supersonic has “sold” 76 supersonic commercial jets to date, the number 76 being, I suppose, a milestone of sorts, with “76” being the year of America’s freedom to create its own percussion sounds.
Boom’s program, whether you believe such a thing as overland supersonic flight will ever happen or not, is still really cool science. It might not mean much to us as pilots of smaller airplanes. For the record, light sport aircraft are restricted by regulation from busting the speed of sound and even Bonanzas would need a redesign. But this research does have important implications in the worlds of commercial air carriers and business air travel. Some of them have never been tried before, too.
Those of us in aviation who scoff at the concept of a “sound barrier” might want to reconsider. Our thinking has always been that the idea was a hand-me-down fiction from late WWII times when all attempts to go faster than the speed of sound were doomed to failure. We knew back then that objects could break the speed of sound. Bullwhips and gym towels were known to do so long before the advent of supersonic airplanes.
But there are very real phenomena that act as, or very much like, physical barriers to objects breaking the speed of sound. The most well known is the sharp, non-linear rise in drag that occurs as an object approaches Mach 1. The push to defeat that rise in drag means planes must be that much more aerodynamically efficient in order to push on through. If that is not a barrier, it is at least one hell of a speed bump. So while sub-sonic aircraft designers could be and are forgiven for being a bit lazy with their aerodynamics…a Piper Cub does just fine with its aerodynamically prehistoric Clark Y airfoil…the same cannot be said for designers of trans- and supersonic craft, where every one of the plane’s curves and bends matter a great deal.
On a somewhat less literal level, there are other very real barriers to planes flying faster than the speed of sound. When I was a kid living in the high desert of Southern California, on a couple of occasions we had windows broken by big booms, and we knew just what it was that caused the breaking glass. Sixty miles to the west was Edwards Air Force Base, and some of what they were up to we knew all about, as the existence of the X-15 and SR71 were long known. We suspected, however, that there might be some even cooler stuff going on that they weren’t talking about. We happily replaced those panes of glass while busy speculating, putty knives in hand, about what the folks at NASA were up to.
Such is not the state of public opinion in most places these days, so the act of flying supersonic over populated areas is right out. In fact, it’s prohibited by international law. But what if, ask the scientists, we could reduce the supersonic signature from a boom to a little pop? It’s hard to imagine how that would upset many people, who in all fairness put up without comment with trucks roaring past on the street and 737s at takeoff power climbing still low over city centers.
Boom is approaching this whole thing in a really smart way, not by pretending it knows all things supersonic or can solve all of the problems inherent in supersonic overland flight by itself. Instead, it’s working with the likes of Honeywell and GE, among others, to make the magic happen.
The company plans to make the first subsonic flights of its smaller scale XB-1 demonstrator from near its home in Denver, Colorado next year with follow-up supersonic sorties departing from Edwards later in the year. The plane, which is about the size of a light to light-midsize jet, will be capable of pushing past Mach 2.2 with its General Electric J85-21 turbojet engines. Yes, relatives of the J85s developed in the 1950s. The avionics for the demonstrator will be by Honeywell, which announced at Paris that it was working on avionics designed to provide routings around people on the ground based on the sonic signature, altitude and population.
It’s all cool tech, and I would like to believe unconditionally that it will result in supersonic airliners. But the economics of supersonic flight are tough, as we learned from Concorde, which set a record for the service life of an airplane that lost a lot of money from day one.
Will the curiously named Boom Supersonic be able to create a pathway to viability? It all depends, as it seems to know, on making its namesake booms into boomlets and convincing regulators that its planes will provide little more than background noise as they wing their way from coast to coast at Mach 2.2.
For now, it remains the stuff as much of sci-fi as actual science. But if Boom can get past the very real regulatory and economic barriers to supersonic flight, the company will certainly make a boom, though they hope that it sounds more like a pop.