NASA’s X-59 Quiet Supersonic Research Aircraft Cleared for Final Assembly
nasa.gov
nasa.gov
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...
Concordes were wasting double digit of their fuel reserve while flying in the holding pattern if runways were not available for some reason.
Though note this was uncommon; they were typically cleared for a direct approach all the way from cruise to touchdown. Part of the reason why they rarely got put in the holding pattern was the fact that it would quickly turn into a low fuel emergency, and part was giving the SST preferential treatment.
And Concorde powerplant had at some point the highest overall thermal efficiency at max speed:
https://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593
The overall thermal efficiency of the engine in supersonic cruising flight (supercruise) was about 43%, which at the time was the highest figure recorded for any normal thermodynamic machine.
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.
As for books, I wholeheartedly recommend the excellent https://www.barnesandnoble.com/w/sled-driver-brian-shul/1123... written by one of the pilots.
You can compensate by cramming in seats closer or trying exotic designs. And there's some efficiency buy-back by operating at higher altitudes where the engine can expand to lower pressures (and thus increase the pressure ratio), but overall, roughly half as efficient is a decent guesstimate.
Then again, conventional aircraft are about double the efficiency they used to be, so supersonic aircraft today could conceivably be approximately the same efficiency as transonic aircraft of yesteryear.
I think exotic designs could enable decent range low supersonic electric flight (i.e. Mach 1.5 or something). Going to need good batteries, though, and extremely high aspect ratio wings.
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
You could maybe get some sort of inflatable lifting body to work at high speeds though.
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:
Some of them they still do. Their air is still less dense, so if you force the same volume out per second, you generate less thrust anyways cause there is less mass per volume (and thus less thrust for you)
Fun fact/rumor: in the early 2000s, Lockheed SW was rumored to have a mature design for a QSP bizjet that they were shopping around to hedge funds for funding into production, since Wall Street were avid customers of the Concorde. Cessna was also working on something that has probably been abandoned.
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.
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.
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.
From another source:
The X-59 has been designed to achieve a PLdB of 75, similar to what might be heard when standing next to a heavily trafficked road.
It will be good to dispel the ideological status quo in aeronautics community that "SST is dead and buried"
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.
For as long as engineering goes, I'm more into electronics and process.
(dunno if that's what it's called, it was the name that sort of felt most right)
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
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