
NASA’s X-59 Quiet Supersonic Research Aircraft Cleared for Final Assembly - hourislate
https://www.nasa.gov/press-release/nasa-s-x-59-quiet-supersonic-research-aircraft-cleared-for-final-assembly
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utopian3
I’ll be super excited to have low-to-null-boom supersonic transcontinental
flights! But if this becomes a passenger plane, what kind of fuel efficiency
would that have? Are supersonic aircraft more or less efficient (oranges and
apples I presume).

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dexen
_> Are supersonic aircraft more or less efficient_

Surprisingly enough, supersonic planes have good fuel economy while
supercruising - thanks to thin air at the high altitude, and speeds around
Mach 2 ... 3 being good for turbojet engines.

Expect worse taxiing, take-off and climb fuel economy, due to dense air and
also suboptimal (high) angle of attack. This means supersonic planes are best
suited for longer routes.

Even the grandpa Concorde had good fuel economy in cruise, however it was
overshadowed by atrocious fuel economy at low speeds, and the use of
afterburners in transsonic region[1]. The designed but never built Concorde
"B" would have notably better economy thanks to more advanced engines doing
away with the afterburners.

[1] [https://www.quora.com/How-fuel-efficient-was-the-Concorde-
co...](https://www.quora.com/How-fuel-efficient-was-the-Concorde-compared-to-
similar-sized-jets)

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everdev
> Expect worse taxiing, take-off and climb fuel economy, due to dense air and
> also suboptimal (high) angle of attack.

This reminds me, in the book "Skunk Works", SR-71 Blackbird pilots mentioned
their schedule of mid-air refueling 20-30min after takeoff. After that they
could make it 3-5hrs at high altitude before refueling again.

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skykooler
This is because the Blackbird took off with only partially filled tanks, to
lower the weight and therefore the takeoff speed. It was not designed to take
off or land with full tanks.

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gpderetta
Also the tanks leaked untill thermal expansion at supersonic speed sealed
them.

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utopian3
Wow, shouldn’t that be a safety concern? Fuel leaking all over the airbase
prior to takeoff?

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selectodude
The fuel was so resistant to ignition that it required an external source (TEB
in this case) to even get alight.

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etrautmann
The attached image of the assembly has a nice easter egg:

[https://imgur.com/a/df6XnAs](https://imgur.com/a/df6XnAs)

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CRUDite
Apart from the Aerion as2 i dont think there are many other credible
supersonic aircraft in development other than the Nasa one. Concorde, other
than the booms, had engines so loud, and i mean insanely loud they would not
be popular these days. I remember covering my ears as it flew overhead.

I do find Elon Musks frequent mentions of a vtol ss aircraft quite
interesting. Electric engines would not have the same issues at high altitude
as conventional ones. Battery density is starting to get in the right area to
make this feasible.

He is frequently distainful of flying cars but one logical conclusion of this
is indeed potentially flying cars (Tesla secret projects anyone?). When you
think about how much of the world is inaccessible, one of these would make a
great thunderbirds style exploration vehicle ( provided it had a large
expandible solar array stowed somehow) . Fancy a trip to the Kamchatka ground
zero? No problem! I wonder whether aerodynamically they would not need to be
so concorde like and maybe just bullet shaped. Perhaps on Mars you could have
supersonic blimps

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implements
> ... had engines so loud, and i mean insanely loud they would not be popular
> these days. I remember covering my ears as it flew overhead.

I lived near Heathrow and Concorde was such a thing of beauty that the noise,
if anything, just added to the spectacle!

Trust me, this never got old:

[https://m.youtube.com/watch?v=i1ShTUVIzCI](https://m.youtube.com/watch?v=i1ShTUVIzCI)

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ethagknight
Haha I personally would love it, but I cannot imagine car alarms going off
would be tolerated on a daily basis! Great video if thats yours. On the flip
side, I think about how we have tornado siren tests every week at 3p, and my
office tower is immediately adjacent to a fire station with the siren on the
rooftop blasting at my window for 2 minutes a week, we have to mute conference
calls and whatnot during the test... its just a part of life.. I mean, surely
they could test those things every month during tornado season and be just
fine.

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JumpCrisscross
Is anyone else around the world working on quiet supersonic passenger jets?

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ghaff
Boom is one company working on supersonic passenger jets. Various others also
pop up from time to time.

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DoofusOfDeath
Perhaps I'm in the minority, but I'm concerned that commercial-supersonic will
be a net-negative in my life.

I'm assuming that, as with the Concords, most of the benefit for supersonic
travel would be to very wealthy individuals and corporations. But everybody
living/working beneath the flight path would have to endure the added noise
pollution.

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ocdtrekkie
The entire point of this concept is removing that noise pollution.
Additionally, a more modern, efficient aircraft than the Concorde might
conceivably someday make sense for more widespread, and hence more affordable
use.

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DoofusOfDeath
> The entire point of this concept is removing that noise pollution.

My understanding was that the noise-reduction was specifically for sonic
booms. If I understand correctly, commercializing this would mean a transition
from _no_ sonic booms to _quieter-than-before_ sonic booms. From my own,
personal perspective that's a net-negative.

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ocdtrekkie
Speaking as someone who used to live pretty close to an airport, I'd point out
that normal airliners are not without noise pollution, and I'd rather it be
gone sooner rather than later.

The faster a plane crosses the horizon, the less of your time will have noise
pollution. Then the question becomes how much quieter these sonic booms are,
and how they compare to more traditional airliners' noise pollution.

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jhayward
The planes you are noticing are all below the 10,000 ft level (i.e., on
approach or takeoff) and are required to fly no faster than 250 knots. No
supersonic aircraft will be flying supersonic on approach or at low altitude.
If their engines are noisy they will be louder for the same amount of time as
others.

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baybal2
I'm very impressed that they managed to keep it going for so long.

It will be good to dispel the ideological status quo in aeronautics community
that "SST is dead and buried"

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ghaff
I'm not sure there's a "dead" status quo around technical feasibility so much
as there's a great deal of skepticism about economically viable commercial
supersonic passenger air travel. (At least, possibly, beyond a niche for the
very wealthy.)

~~~
baybal2
See, building aircraft is not so really that expensive. First supersonic
aircrafts were built with manufacturing equipment which will not sell even on
a liquidation sale today.

Military jet bombers, while expensive by all measures, did cost less in the
mid-20th century than equivalently sized airliners today.

A lot of cost increase since eighties in the industry was due to increasing
regulatory lockdown and decrease in efficiency due to decrease in competition.

The $100 per piece "aerospace grade" nuts and bolts is exactly what I am
talking about.

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starpilot
You seem to know a lot of things. Do you have like a newsletter I could
subscribe to?

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baybal2
I'm not really into aircraft engineering. I had a dip in it when I was really
into drones in my high school years, and then tried myself at motogliders.

For as long as engineering goes, I'm more into electronics and process.

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gertrunde
+1 for the googly eyes and mustache on the forward bulkhead...

(dunno if that's what it's called, it was the name that sort of felt most
right)

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homonculus1
A bulkhead is a wall inside a ship. The main structure of an aircraft is
called the _fuselage_ and the outer surface is the _skin_.

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api
Looks like its landing on Tattoine, which is appropriate for that thing.

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0xffff2
It's almost certainly a render of the plane landing at Armstrong Flight
Research Center (longstanding home to the NASA X planes), which does in fact
bear a striking resemblance to Tattoine.

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homonculus1
Tunisia looks a lot like Tatooine too!

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The_rationalist
How many seats?

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cheeko1234
This is an experiment rather than a finished product:

The X-59 will never carry passengers, but it will likely kick off a new
generation of quiet supersonic commercial planes that can fly over land and
dramatically reduce the time it takes to get you across the U.S. and to other
countries.

[https://www.nasa.gov/nasa-x59-quesst-takes-
shape](https://www.nasa.gov/nasa-x59-quesst-takes-shape)

The Quesst is an experiment to see if the annoyingness of the boom can be
mitigated by converting the boom into a "thump" (i.e. quieter boom).

Src: I work there

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The_rationalist
As for the boom, why don't they just wait to be in very high altitude or to be
at a place where there's almost no human in the surroundings?

