The new SSTs & Congress may create some disconcord

supersonic flight congress safety
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Supersonic Transport

Timelines for Safety & Environment

For those who may have no knowledge of the international competition to build a commercial Supersonic Transport, the history is filled with intercountry pride, governmental financing (or not?), brilliant engineering, contentious, litigious environmental battles and operations which did not nor could not break even based on private enterprise accounting.

concorde supersonic history

Suffice it to say, the battle was a major aeropolitical debate around the globe. Some would say that its environmental impact was the cause of its death. Others would assert that the technology (powerplant and airframe) was not mature enough. The data would assert that its operational costs exceeded the price which passengers were willing to pay for the faster, shorter flights.

The SST debate is BACK:

nasa supersonic flight

Not surprisingly, the US Congress has weighed ina bill supporting ending the ban on supersonic flight, voices urging moderation and environmental opposition are all before Capitol Hill:

top airplane speeds records

There are many SST prototypes being developed around the world (Japan, Russia and China; US— Aerion). Boom, a Denver based company and a staunch supporter of Lee Gardiner, calls its plane XB-1 will fly at 2.2 times the speed of sound. It supports the bill because it would also establish a deadline for a rulemaking to allow civil supersonic flight over the United States for the first time since 1973.

The XB-1 is the only proposed commercial supersonic aircraft. The specifications project that this plane would reduce supersonic fuel burn, lower ticket prices, extend aircraft range, and reduce carbon emissions. 

boom xb-1 supersonic flight

To add to the hopes and expectations of the SST Renaissance industry is new technology which NASA and Rockwell Collins are working on. They have developed “a way to visualize a sonic boom.” The goal is to give pilots a tool with which to adjust their flight plans to reduce the noise heard on the ground. That’s a key obstacle for the new generation of supersonic aircraft, which need to be able to fly over land.

Another NASA project (this one in conjunction with Lockheed) is based on a hypothesis that they can change the paths of the shockwaves caused by supersonic flight. By simply locating a single engine on top of the plane should create a “sonic thump” instead of the jarring boom.

sonic boom carpet

In supersonic flight, the plane’s fuselage forces a gap in the air molecules and that phenomena creating shockwaves that are similar to a boat’s bow wave. That wave of air molecules hits the ground surface and creates a sharp noise called the boom carpet.

supersonic transport nasa

NASA’s and Lockheed’s research shows from modeling that these waves emanating from the aircraft waves can be made to not pile up on one another. The data shows that the engine on the top of the fuselage results in the spacing the waves farther apart, creating a less jarring “shaped boom.” Part of the problem with current supersonic booms is “the startle factor.” Peter Iosifidis, a Lockheed Martin engineer who manages the Quiet Supersonic Technology (QueSST) program said, “When you look at traditional supersonic airplanes, they weren’t designed for a low sonic boom. They were designed for speed, and some might argue, efficiency.”

The optimism associated with these evolving technologies needs to be tempered by the reality of the public’s heightened sensitivity to noise— hyperacusis as well as increased expectations of the populace to “quiet” enjoyment of their property. The FAA has encountered stiff resistance to the implementation of environmentally positive (on a macro basis) NextGen Flight paths.

The testing of the BOOM, AERION and other SSTs must include rigorous assessment of psychoacoustics to be sure that the perceptions (the science of human hearings, acoustics, has found that the peoples’ response includes a heavy subjective component) are acceptable. A well-designed education program to explain the technical difference between the N-Wave and the shaped boom may improve the introduction of these innovative aircraft.

If, as expected, the reintroduction of the SST receives major environmental opposition, the FAA in approving these new aircraft should call the NASA-identified new boom as the Lee-Gardiner sonic boom.

Technology advancement is difficult because the government must design standards to assess the new aircraft, in the FAA sphere. Entrepreneurs have invested billions of dollars to create aircraft innovation and that significant risk capital outlay demands a short time in which to recoup that investment. The timelines for safety and environmental certification are not as susceptible to abbreviation as the financial backers would like. Compressing the time to issue an NPRM is one thing and if enacted, the FAA will struggle to get the work done in time. Hopefully, Senators Lee and Gardiner will not demand that safety and the environment be given short shrift.

supersonic transport aerodynamics

 


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