I remember as a kid hearing sonic booms and thinking it was so cool. I guess it was military planes in my area. I wonder how many people now even knows what it sounds like.
The article mentions commercial air flights taking half the time, but I wonder who needs that kind of speed when I see this-
“According to ICCT, supersonic flights would burn up to 9x more fuel per passenger per kilometer than their subsonic flying buddies.“
When I was a kid, my dad was a naval officer stationed on an aircraft carrier and I got to go on something called the “Dependent’s Day Cruise” where we sailed out offshore and got tours of the ship and they did a full-on airshow for us. Because we were out at sea, they could break the sound barrier with impunity, and it was mind-blowingly cool to have fighter jets flying over low enough that we could see the pilots, absolutely silently until that massive shockwave hit your chest. It’s surreal.
> would burn up to 9x more fuel per passenger per kilometer
That number seems a bit hyperbolic, even for Concorde, which was 1960s technology. Modern supersonics will be far lighter, use turbofans instead of turbojets, not require (or even have) afterburners etc.
They also claim that they will be net-zero Carbon due to advances in sustainable aviation fuels, with processes like CO2-fuel direct air capture.
The Concorde is still pretty top notch, tech wise. As far as supersonic and supercruise jet engines go, they are all military. Civilian engine development went all in improving noise levels and fuel economy. And without a viable market, no engine OEM will invest the billions needed to develop a civil supersonic engine. So it is either a huge market, or various governments foot the RnD bills. Both of which are far, far away.
All technological promises regarding civilian supersonics only exist in fancy renderings and pitch decks, there is no substance behind. Even less than there is with the various eVTOLs, at least those actually fly. Well, some of them that is...
The 9x factor seems in the ballpark when you consider a Mach 2 jetliner will be going 2.5-3x faster than a subsonic one, and drag increases with the square of the airspeed.
My girlfriend and I were hanging out at a lake east of Issaquah near seattle and suddenly two Growlers came down low over the lake and we were subject to two sonic booms which was amazing. They sounded sort of like a resonant crack of thunder but much louder. They flew over a boat in the middle of the lake and I shit you not someone on it screamed "AMERICA F YEAH." It turned out this lake was one of the ones they filmed for the new Top Gun film, but it was common for Whidbey pilots to buzz it on their way back to the NAS.
My daughter lives relatively close to Cape Canaveral and hears sonic booms from the returning Spacex first stage quite frequently, as does the surrounding neighborhood.
I read some contemporary articles in a Private Eye annual from the 1960s and the problem was not really the noise but the structural damage that was (allegedly) being caused. I don't know how real that was, but in the UK concerns over structural damage to buildings was what lead to the ban.
As for this plane, what are the elements of the design that reduce sonic booms? The comically long nose?
Given that it’s 14ft tall, I’d say no, though I agree they could’ve made it clearer. It says 99’7 In, or 99 feet and 7 inches (ideally, it would be 99’7”).
Is there a rule / scaling relationship about the maximum passenger volume + payload of a supersonic aircraft and the fuel burn? Just wondering if by physical law, these transports are destined to be only ever extremely premium / luxury travel.
Energy argument follows: higher speed = higher drag (increases with square of speed) = higher thrust to overcome that drag = more fuel = more weight = more structure overall (larger wings etc.).
Higher speed -> you reduce the angle of attack -> lower cross-section. The drag per unit of area increases, but the area decreases. Overall, you still have higher drag, but you get faster to where you need to get. It is not pre-ordained that you need to burn more fuel overall.
In fact, you can end up burning less, not more fuel.
Here's why: drag per se doesn't matter. What matters is the lift-to-drag ratio [1]. To keep the plane at a constant altitude, the lift needs to be equal to the gravitational force acting on the plane. To keep the plane at constant speed, the thrust needs to equal the drag. If the lift-to-drag ratio is 10, the thrust needs to be one tenth of the weight of the plane.
Now, the fuel consumption per second is roughly proportional to the thrust. If you double the speed and the lift-to-drag ratio gets cut in half, your overall fuel consumption is the same. But here's the thing: in supersonic regime, the lift-to-drag ratio does not get cut in half. The empirical lift-to-drag ratio is 4(v+3)/v, where v is expressed in Mach number. For example at Mach 3 you get LTD ratio = 8 and at Mach 6 you get 5.33.
Of course, things are not that rosy: on one hand the airplane needs to be sturdier, because it needs to withstand higher vibrations. On another hand, even if in cruise mode you may save fuel, it's difficult to optimize the plane in a very wide range of velocities. Concorde was horrible at low speeds, so it was burning a lot of fuel at take-off; it is quite obvious that a plane is the heaviest at take-off, so if you burn more fuel at that point, you really burn more fuel.
But design has made huge advances in 50 years. We may be able to optimize better an airplane now than we could when the fastest supercomputer was slower than the iPhone in your pocket.
Bottom line: it is not at all obvious that a supersonic plane needs to burn a lot of fuel, and it may be that it could actually burn less than a subsonic one.
I'm curious to see the fuel efficiency. Wind resistance has to be way way higher at these speeds, but it also appears to be flying at much higher elevation so they may cancel out to a certain degree.
Even if fuel economy was somehow better, it would still lead to more fuel getting burned. Because the super rich only have so much time in their lives to spend in the stratosphere or elsewhere and shorter flight times could noticeably shift their trade-off decision about the inconvenience of flying vs the inconvenience of not being where they'd like to be. Outliers in wealth aren't quite as much outliers in ecological footprint because fortunately there's only so much you can consume, but a supersonic revival would help close that gap.
A part of me sure loves the nostalgic idea of technological bigger-better-faster, but the rest is fully aware that this is not the progress we are looking for. It's bad enough when private investors put money into destructive technology like this, but if it was my tax money, I'd be shouting at them.
"Creates a sound as loud as a car door closing" -> I assume this means at ground level? I can't imagine even the propulsion being that quiet let alone the sonic boom.
Yes, the noise level is measured on the ground directly below the flight path of the plane.
Interestingly, it’s not just the volume but also the pattern of the boom that can be altered by changing the design of the plane. There’s a great discussion of this here: https://www.elidourado.com/p/50-years-supersonic-ban
(Scroll down to the images of the sound wave)
It’s nice when they put it like that. Now imagine you trying to relax or concentrate in your home and hearing a “car door closing”, every minute, regularly, all day. And if in the end it sounds more like the car’s tire blowing up - well… “we are looking at ways to resolve the issue”, “we are aware of the issue and working on it”, “you are the only one complaining”, “it looks you may be too sensitive to noise”, and so on. Who cares in the end. It’s just people.
Unrelated but... My brain can't tell me if 14 foot is a lot or not... I can't imagine how is it possible to do CAD design in imperial measures, it was always making me think why is not whole world moving to metric- is it not a de-facto standard now?
Too fast for it to be useful I'd guess, you're reliant on the computer anyway so why have a front window be a design constraint restricting aerodynamics, tough enough glass/plastic (a lot more force on it than the overhead/side window it does have) etc.?
Readit News
The article mentions commercial air flights taking half the time, but I wonder who needs that kind of speed when I see this-
“According to ICCT, supersonic flights would burn up to 9x more fuel per passenger per kilometer than their subsonic flying buddies.“
That number seems a bit hyperbolic, even for Concorde, which was 1960s technology. Modern supersonics will be far lighter, use turbofans instead of turbojets, not require (or even have) afterburners etc.
They also claim that they will be net-zero Carbon due to advances in sustainable aviation fuels, with processes like CO2-fuel direct air capture.
The truth will probably be somewhere in-between.
This fig leaf is transparent.
All technological promises regarding civilian supersonics only exist in fancy renderings and pitch decks, there is no substance behind. Even less than there is with the various eVTOLs, at least those actually fly. Well, some of them that is...
As for this plane, what are the elements of the design that reduce sonic booms? The comically long nose?
https://www.thedrive.com/the-war-zone/44307/behold-the-x-59-...
Is metric used to actually design the plane, or does Skunkworks still use US customary measurements?
Your question did make me think of the Boom XB-1; a scaled down version of a passenger jet that I'm skeptical will ever fly commercially.
https://www.instagram.com/p/Cp-YjLNDUf6/
Can it fly from New York’s Idlewild Airport to the Belgian Congo in 17 minutes?
I'm guessing it should read 99ft 7in. That would put it at just over 3m, which still seems pretty small to me.
Yep.
> That would put it at just over 3m
Nope.
Higher speed -> you reduce the angle of attack -> lower cross-section. The drag per unit of area increases, but the area decreases. Overall, you still have higher drag, but you get faster to where you need to get. It is not pre-ordained that you need to burn more fuel overall.
In fact, you can end up burning less, not more fuel.
Here's why: drag per se doesn't matter. What matters is the lift-to-drag ratio [1]. To keep the plane at a constant altitude, the lift needs to be equal to the gravitational force acting on the plane. To keep the plane at constant speed, the thrust needs to equal the drag. If the lift-to-drag ratio is 10, the thrust needs to be one tenth of the weight of the plane.
Now, the fuel consumption per second is roughly proportional to the thrust. If you double the speed and the lift-to-drag ratio gets cut in half, your overall fuel consumption is the same. But here's the thing: in supersonic regime, the lift-to-drag ratio does not get cut in half. The empirical lift-to-drag ratio is 4(v+3)/v, where v is expressed in Mach number. For example at Mach 3 you get LTD ratio = 8 and at Mach 6 you get 5.33.
Of course, things are not that rosy: on one hand the airplane needs to be sturdier, because it needs to withstand higher vibrations. On another hand, even if in cruise mode you may save fuel, it's difficult to optimize the plane in a very wide range of velocities. Concorde was horrible at low speeds, so it was burning a lot of fuel at take-off; it is quite obvious that a plane is the heaviest at take-off, so if you burn more fuel at that point, you really burn more fuel.
But design has made huge advances in 50 years. We may be able to optimize better an airplane now than we could when the fastest supercomputer was slower than the iPhone in your pocket.
Bottom line: it is not at all obvious that a supersonic plane needs to burn a lot of fuel, and it may be that it could actually burn less than a subsonic one.
[1]https://en.wikipedia.org/wiki/Lift-to-drag_ratio
A part of me sure loves the nostalgic idea of technological bigger-better-faster, but the rest is fully aware that this is not the progress we are looking for. It's bad enough when private investors put money into destructive technology like this, but if it was my tax money, I'd be shouting at them.
It's also not a place you'd want to spend too much time considering you're outside of the radiation protection of a large part of the atmosphere.
Interestingly, it’s not just the volume but also the pattern of the boom that can be altered by changing the design of the plane. There’s a great discussion of this here: https://www.elidourado.com/p/50-years-supersonic-ban (Scroll down to the images of the sound wave)
https://www.faa.gov/newsroom/supersonic-flight
But I know I'm just over 6 foot tall, I know a foot is about the length of a ruler.
Acres are completely alien to me, same with lbs and oz's