NASA's new jet will fly faster than the speed of sound without the supersonic boom


#1

Originally published at: https://boingboing.net/2018/04/17/nasas-new-jet-will-fly-faste.html


#2

For those like myself who were wondering “WTF HOW?!?”…

The answer to how the X-plane’s design makes a quiet sonic boom is in the way its uniquely-shaped hull generates supersonic shockwaves. Shockwaves from a conventional aircraft design coalesce as they expand away from the airplane’s nose and tail, resulting in two distinct and thunderous sonic booms.

But the design’s shape sends those shockwaves away from the aircraft in a way that prevents them from coming together in two loud booms. Instead, the much weaker shockwaves reach the ground still separated, which will be heard as a quick series of soft thumps – again, if anyone standing outside notices them at all.

From: https://www.nasa.gov/lowboom/new-nasa-x-plane-construction-begins-now

So, essentially, we’ve just been doing the aerodynamics wrong until now. Cool!


#3

“… plans to replace the sonic boom with a “gentle thump” sound that is likened to a car door closing. “

Sound of a car door closing? That “trigger” will create mass confusion among the millions of faithful dogs who rush to meet their master at the front door.


#4

What’s the mileage target?


#5

And cats. My cat always greets me at the door.


#6

No sonic boom?

Guile is unhappy
Guile-SF2-Sonic-Boom


#7

I’d say, yes and no… sort of. Being ‘back in the day’, there was much more consideration for the aerodynamic design required to achieve sustained supersonic speeds than for the environmental (acoustic) impact to the public. If the latter had seriously been in play, then the former would have involved more research ($$$$) in getting everything right.


#8

I stand corrected.


#9

That’s a breathless writeup for a one-off demonstrator.

Unless they figure out a way to go supersonic without burning too much extra fuel this is not going to turn into a commercial product. At least not one that you’ll be able to ride. At best there might be a tiny market for supersonic bizjets for billionaires that uses this technology.

The fundamental problem with supersonic flight is that drag goes up with the square of velocity so you have to burn way more fuel to sustain supersonic speeds. That makes the tickets expensive and people quickly ask themselves if they are willing to spend an extra $3000 on that $400 ticket to shave 3 hours off of the flight time. It’s a tough sell, and the low volume causes the prices to be even higher as you have to maintain a fleet of specialized high performance aircraft. And then you lose all of the time savings because your expensive supersonic plane only flies between hubs (where it can be maintained), so most people end up with a layover–one they wouldn’t have had if they had taken that direct flight on the cheaper subsonic airline flight.


#10

Oh, you’re no fun anymore…


#11

The air pressure at 60000 feet (20 km) is 4 times lower than at 30000 feet (10 km), so that will reduce quite a bit of friction. So, if I’m not mistaken, and my guess that friction will go up by the power of two with speed and diminishes linearly with the air pressure, they could fly at double the current speed and expend an equal amount of fuel.

Bert


#12

no, it still creates a sonic boom, it just aims it up.
So it’s like one of those Rainbow editions where his flash kick shoots a fireball and his sonic booms are anti airs.


#13

No more Boom Boom for you.


#14

Concorde ended its flights due to the deafening sonic boom, which lead the FAA to ban most of its flights

The Concorde ended its flights because it hemorrhaged money for decades and then had a spectacular fatal crash.

(Also, you mean “which led the FAA to ban. . .”. That’s a tricky one, with the present tense having an “a” and the past tense sounding like the metal, which also has the “a”.)


#15

I pity the people who live near airports where this thing will be taking off from. The noise will be deafening. While sonic booms occur during flight the thrust to get that frame into the air will be off the decibel charts. I guess with all this deregulation going down in the trump admin it will be a free for all across the country.

Note: There is still nobody in charge the FAA. Current efforts to control airport noise around the U.S. are being met with FAA no-shows to working group meetings.


#16

You beat me to this comment! That one sad crash finished it off. It was a shame, because had I known the Concorde was going to go away, I would have taken advantage of putting up $500 to upgrade a first class seat someone else paid for to fly Concorde in both direction on my trip to Saudi Arabia via Paris rather than just one way to Paris from NYC.


#17

Did you buy a house next to an airport or something? Better than a floodplain, I guess. I live near the largest air force base in the world, and I’ve never had a problem despite the unregulated nature of military aircraft.

According to the FAA website, no commercial aircraft is allowed to exceed 110 dB.

The video says they aren’t asking for this to change, they just want supersonic jets to also have to follow this same requirement, rather than the current regulation, which is an outright ban regardless of decibel level. It seems entirely reasonable to me to apply the same standard to all commercial aircraft.


#18

What the video really taught me is that we are wasting 4 hours screwing around on the ground before and after the flight. Screw faster planes. What we need are faster airports.


#19

Bunny and Tigra will not be happy about this.


#20

Load a plane from the back to the front? Impossible! How would the 1st class passengers be able to lord their comfort over the plebs?