NASA/Lockheed Martin X-59A Quiet Supersonic Technology (QueSST)

Orionblamblam said:
Yup. The trick is *what* particulate. Something that will reflect sunlight during the day and filter down out of the sky by night and not cause environmental ruin. I wonder if studies can determine whether getting spewed by an SST would be better than a subsonic jet.
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You did miss some sarcasm in there.
 
martinbayer said:
I guess that's why they're called testbeds...
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The difference being that the SSBD tried a novel and possibly practical configuration, whereas the X-59 is a configurational dead-end that could have come off a 1950s sketchpad.

Why not put the money towards something potentially practical, like an airliner-proportioned fuselage using adjustable aerospikes and ventral ramps? Then we'd get sound-pressure data plus a starting point for a usable design.
 
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Kiltonge said:
The difference being that the SSBD tried a novel and possibly practical configuration, whereas the X-59 is a configurational dead-end that could have come off a 1950s sketchpad.

Why not put the money towards something potentially practical, like an airliner-proportioned fuselage using adjustable aerospikes and ventral ramps? Then we'd get sound-pressure data plus a starting point for a usable design.
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Because the X59 will fly to determine what the maximum legally allowed sonic booms would be.

Then you build a commercially shaped plane to make booms at that level.

Remember, supersonic flight over land is generally banned! You need to determine what levels the public is willing to tolerate in order to change the flight restrictions, and determining those levels is exactly what the X-59 is designed to do.
 
Kiltonge said:
The difference being that the SSBD tried a novel and possibly practical configuration, whereas the X-59 is a configurational dead-end that could have come off a 1950s sketchpad.
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You are grossly misunderstanding the roles of the two aircraft.

The SSBD was the experimental proof that you could manipulate sonic boom loudness via airframe shape, as was the "Quiet Spike" tested on an F-15. The Quiet Spike didn't do enough on its own to reduce boom levels, so the SSBD got into how to shape an airframe to reduce sonic booms.

The X-59 is to establish the tolerance levels of the public towards sonic booms, to inform the regulation changes for just how much boom is allowed over land. It's not supposed to be an operationally representative shape for a commercial passenger hauler or even a business jet.

Only once the boom levels are established can we start designing a commercial airframe to meet them, likely using some combinations of the Quiet Spike and a whole lot of airframe shaping.
 
So my contribution to this vehicle is that I worked at NASA Armstrong Flight Research Center in Code-421, the Avionics and Instrumentation Branch. I worked in the Research Aircraft Integration Facility's "Dryden Avionics Lab" where we had mockups of the bays that the data acquisition units were to go in. I'd build the wire harnesses and flight hardware for the DAUs and install them in the mockup to check fit and function. I performed pressure tests on the pitot static manifold as well. I also read the FADEC controller manual for the engine and determined a lot of the signal pathways between the engine and the aircraft sensors, and wrote a summary of this for the benefit of my coworkers.
 
It has been so far interesting to see how such an experienced team as NASA and LM managed to be so much slower during the same time than Boom, a newbie, with a very similar airplane (only the supersonic tests in effect differentiate them).

But let´s rejoice that the Ice Age of US shiny aviation has ended with the election.

TheIceAgeHasEnded .jpg
 
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Scott Kenny said:
Good, I want the data for acceptable sonic boom footprint soon! (Yeah, it's gonna be like 4-5 years out, minimum. Doesn't stop me from wanting it sooner!)
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Plenty of studies have already been carried out. We know what people will tolerate; the USAF flew hundreds of sorties in the 1960s and 70s to determine that.

What we don't know is how to build a practical airframe to achieve that.

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Kiltonge said:
Plenty of studies have already been carried out. We know what people will tolerate; the USAF flew hundreds of sorties in the 1960s and 70s to determine that.

What we don't know is how to build a practical airframe to achieve that.

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Right. All that data shows that basically NO sonic boom would be acceptable at 0.3lb/ft^2 overpressure levels, looking at the Nellis data showing ~25-30% high annoyance.

Getting the Loudness Equivalent down to "distant thunder" instead of BOOMBOOM! is probably the only way to get that tolerable to the general population instead of just tolerated by the aircraft nerds.
 

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