Boom Supersonic Overture M1.8 SST

Scott Kenny said:
Then, when the FAA finally comes up with a specification for maximum footprint noise level and profile (not just sheer overpressure or decibels, but whether one large boom or multiple smaller booms etc), Boom will have confidence that what their computer models say will happen actually will happen on the full scale prototype.
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Boom isn't trying for quiet supersonic. Their plan is to fly subsonic (at Stage 4 noise levels, IIRC) until they get over water, then crank it. Which is why they can't make it as a bizjet, because bizjets aren't often used exclusively for overwater routes.
 
djfawcett said:
That is if they are building with sonic boom suppression in mind. Boom is not. They are building for routes where sonic boom is not an issue - i.e. - over water for the most part.
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Combined response:
TomS said:
Boom isn't trying for quiet supersonic. Their plan is to fly subsonic (at Stage 4 noise levels, IIRC) until they get over water, then crank it. Which is why they can't make it as a bizjet, because bizjets aren't often used exclusively for overwater routes.
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I believe that is a terrible business model.

Assuming that their airframes do get bought, that means that any airline who bought Boom would be disadvantaged compared to a company that bought quiet supersonics. (I'm using the SouthWest Airlines model here, one pool of pilots, one pool of mechanics, etc)
 
NMaude said:
I'm baffled by the fact that the pilot doesn't appear to have an ejection-seat.
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My best guess is because it's not meant to operate in a hostile/combat/unknown environment/flight envelope.
 
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Halcyon66 said:
Not sure how that works, orders for what exactly?

Regards,
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It's a paper option. So the airline pays a negotiated payment as sort of a down payment on a purchase option at a set price per airframe.
Boom says, I'll sell you X-number of airframes for $150m. United says, I'll give you Y-dollars to secure a rolling option for X-number of airframes at $150m if you can deliver by 2035.

Because Boom has nothing to sell but hope to investors right now, the options are probably extremely cheap. They might be willing to take a loss on the first orders just to secure the funding now and have the orders in the pocket.

It's good for the airline because it gets their name in the paper with the word supersonic next to it and it locked down a price. Even if Boom later decides to price it at $200m per airframe later, the airline has a contracted option at X-number for $150m. It gives Boom a relatively small amount of money up front, and they can tell investors they have pre-orders.
Win-win. Usually. Airlines do it seed technology they want and will use for a relatively very small amount of money up front. They are gambling with their spare change knowing the preorder helps get Boom to the finish line and locks down what is usually a bargain price for purchasing.

If they buy options or a rolling option from Airbus, it's going to be much more expensive, because Airbus is selling a well-defined purchase date or product. From a start up, it's just seed money and a locked in price.
 
I am all for Boom but I think at this stage we are all wondering how much they spent to get beyond the Mach wall. I see a lot of video and many short flights in restricted airspace. I fear now it's time to increase that pace to get to their test corner faster.
We haven't yet seen things that regulators will embrace, like stalls and spins, max Alpha and cross wind landing, aborted takeoff and heavy touch downs... An airliner, even a fast one, is a bit more than a needle than can zip through the air. Safety is first, even beyond the Mach speed.
 
Flyaway said:
Decision to do our own engines was probably the single most important one in Boom history. Company most likely would have died waiting for the big guys to get stuff done.
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I wish them the best of luck, but it is a fact that the entire history of aviation shows that prototypes which also used brand new, untested engines didn't fare very well... A proven engine will allow to focus solely on fixing the airframe's problems. But when both the airframe and the engine are new, it's harder to tell if the aircraft's problems result from one or the other, or a combination of both.
 
This Flight Defines the Next 100 Years of Aviation
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This is beyond ridiculous. I mean, if my grandmother could run supersonic we would call her a Concorde.

It's a paper option. So the airline pays a negotiated payment as sort of a down payment on a purchase option at a set price per airframe.
Boom says, I'll sell you X-number of airframes for $150m. United says, I'll give you Y-dollars to secure a rolling option for X-number of airframes at $150m if you can deliver by 2035.

Because Boom has nothing to sell but hope to investors right now, the options are probably extremely cheap. They might be willing to take a loss on the first orders just to secure the funding now and have the orders in the pocket.

It's good for the airline because it gets their name in the paper with the word supersonic next to it and it locked down a price. Even if Boom later decides to price it at $200m per airframe later, the airline has a contracted option at X-number for $150m. It gives Boom a relatively small amount of money up front, and they can tell investors they have pre-orders.
Win-win. Usually. Airlines do it seed technology they want and will use for a relatively very small amount of money up front. They are gambling with their spare change knowing the preorder helps get Boom to the finish line and locks down what is usually a bargain price for purchasing.

If they buy options or a rolling option from Airbus, it's going to be much more expensive, because Airbus is selling a well-defined purchase date or product. From a start up, it's just seed money and a locked in price.
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Fun fact: Concorde by 1972 also had 130 -something "orders". Guess what happened the next year, even before the first oil shock in october ? the orders dried out, right off January 1973 starting with PanAm. https://simpleflying.com/concorde-orders/

I believe that is a terrible business model.
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Readily agree. Supersonic over water only ? it's like saying aloud "oops, we didn't properly solve that pesky sonic boom issue." It's a suicide note.
Concorde back in the day ran against sonic booms, because NIMBY angry people. Back then global warning and CO2 emissions were not a concern. Today however : they are. Massively.
Just ask Boeing and Airbus which trend is the most important : going faster, or going with less CO2 ?
Boom is running straight into a brickwall, like Aerion before them.
They are running against their time. Also "flying supersonic is a rich man pollution fest."
 
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TomcatViP said:
I am all for Boom but I think at this stage we are all wondering how much they spent to get beyond the Mach wall. I see a lot of video and many short flights in restricted airspace. I fear now it's time to increase that pace to get to their test corner faster.
We haven't yet seen things that regulators will embrace, like stalls and spins, max Alpha and cross wind landing, aborted takeoff and heavy touch downs... An airliner, even a fast one, is a bit more than a needle than can zip through the air. Safety is first, even beyond the Mach speed.
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Their current design they are working on is so far removed from this prototype that I'm not sure the regulatory aspect plays into it yet.
This is current flight test program is essentially about saying, "We have competent engineers and can actually build hardware that works, and our models we're using to design (hopefully) have demonstrated high fidelity to flight test conditions."
Things investors like to hear.
 
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Josh_TN said:
If true, that would more than justify the demonstrator. That would potentially open up a much larger market of overland routes.
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It's a well-known phenomenon.


Sonic Boom Refraction

Depending on the aircraft's altitude, sonic booms reach the ground two to 60 seconds after flyover. However, not all booms are heard at ground level. The speed of sound at any altitude is a function of air temperature. A decrease or increase in temperature results in a corresponding decrease or increase in sound speed.

Under standard atmospheric conditions, air temperature decreases with increased altitude. For example, when sea-level temperature is 58 degrees Fahrenheit, the temperature at 30,000 feet drops to minus 49 degrees Fahrenheit. This temperature gradient helps bend the sound waves upward. Therefore, for a boom to reach the ground, the aircraft speed relative to the ground must be greater than the speed of sound at the ground. For example, the speed of sound at 30,000 feet is about 670 miles per hour, but an aircraft must travel at least 750 miles per hour (Mach 1.12, where Mach 1 equals the speed of sound) for a boom to be heard on the ground.
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So will the production aircraft feature a modified nose to stop Sonic Booms from happening? That after all was what plagued Concorde through out it's career.
 
TomS said:
It's a well-known phenomenon.

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Fascinating, that led me to a 2016 NASA paper:

Mach Cutoff Analysis and Results from NASA's Farfield Investigation of No-Boom Thresholds - NASA Technical Reports Server (NTRS)

In support of the ongoing effort by the National Aeronautics and Space Administration (NASA) to bring supersonic commercial travel to the public, the NASA Armstrong Flight Research Center and the NASA Langley Research Center, in partnership with other industry organizations and academia...
ntrs.nasa.gov ntrs.nasa.gov
NASA_Mach_cutoff.png
 
FighterJock said:
So will the production aircraft feature a modified nose to stop Sonic Booms from happening? That after all was what plagued Concorde through out it's career.
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If they are relying on Mach cutoff, they don't need to reshape the aircraft. Any supersonic aircraft can benefit, because the effect basically is a function of altitude/temperature.

The paper @Kiltonge posted is quite informative. In a perfect world, you can get up to Mach ~1.3 without an appreciable boom reaching the ground, but they found that in practice, they were getting booms to the ground at Mach 1.17 and just about 39,000 feet in some trials. So it's a really limited capability.
 
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TomS said:
but they found that in practice, they were getting booms to the ground at Mach 1.17 and just about 39,000 feet in some trials. So it's a really limited capability.
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The Concord for example had a cruising altitude of 60,000Ft so that I imagine would have some mitigating effect on how low the boom was at sea-level.
 
But in their marketing material they used to claim only something like mach 0.9 over land , now they are just pumping it ,aside from possibly new engines only conceptual change from the 70's is synthetic vison vs old drooping noses
 
TomS said:
but they found that in practice, they were getting booms to the ground at Mach 1.17 and just about 39,000 feet in some trials. So it's a really limited capability.
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Just had one of those 'Eureka' moments; read a long time ago that Concorde didn't boom until about Mach 1.15, depending on conditions, which gave the pilots some leeway in where they could start accelerating. Now it makes sense why...
 
Well among Concorde ancestors is a Handley Page Mach 1.15 airliner which tried to play smart with the boom to get a little faster than a CV-990... only to run right into a brickwall called transonic drag. As Boeing found later with its Mach 0.98 Sonic Cruiser: it isn't worth the hassles. Only perhaps bizjets can afford Mach 0.92 or Mach 0.94...
 
Archibald said:
Well among Concorde ancestors is a Handley Page Mach 1.15 airliner which tried to play smart with the boom to get a little faster than a CV-990... only to run right into a brickwall called transonic drag. As Boeing found later with its Mach 0.98 Sonic Cruiser: it isn't worth the hassles. Only perhaps bizjets can afford Mach 0.92 or Mach 0.94...
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Yep, your best cruise speed is about M0.82 or 0.84. Faster than that and the transonic drag spikes and burns fuel way faster.

So you either cruise distinctly subsonic in the M0.8 range or above M1.2. And even the mighty Blackbirds needed help pushing through M1.
 
NMaude said:
The Blackbird would go into a shallow powered dive when accelerating to supersonic speed.
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Yeah, the dipsy doodle flight path maneuver probably wouldn't go over too well with supreme speed superior class paying passengers while they're trying to scarf down Beluga caviar with a generous helping of Dom Pérignon...
 
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Scott Kenny said:
Yep, your best cruise speed is about M0.82 or 0.84. Faster than that and the transonic drag spikes and burns fuel way faster.

So you either cruise distinctly subsonic in the M0.8 range or above M1.2. And even the mighty Blackbirds needed help pushing through M1.
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I think Bombardier has the best option on the table at the moment with a long-range cruise of 0.85, transcontinental of 0.92 and 'get me there' at 0.94.

Plus 'showboating' at 1.015...
 
Scott Manley has just uploaded a video concerning the Boom XB-1 SST demonstrator:


The US banned supersonic flight in 1973, partly because of the noise, partly because US plane builders had decided they didn't want to compete with Concorde. However, NASA kept working on the boom problem, developing new understanding of how sonic booms form and propagate, and in turn technologies which might mitigate these.
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Last week Boom Supersonic announced they wanted to get the FAA rules modified to be based on sound levels, rather than sound speeds, and now NASA is gearing up to fly their X-59 Quiet supersonic test aircraft.
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Selected References:
https://ntrs.nasa.gov/api/citations/2...https://www.youtube.com/redirect?event=video_description&redir_token=QUFFLUhqa0RPY2tuQWwtNUozQlNUd0NadW00ZHNsR2JrZ3xBQ3Jtc0tuWFlkSzJIemt2UHVXU2J4dGRRYmJQTHU3YlpvZkk1d0ZyVzNDZkdrenc4SFhsMVRoZEJSSXRJcjdBdW9vVERmRC00VFFlWV93QXpoSk1ZVlZoMHl4OG1la2VnOWJuM0MxVDdVM2R2MG5EcExRUHlYQQ&q=https://ntrs.nasa.gov/api/citations/20220005452/downloads/Rathsam%20DATAWorks%202022%20Presentation.pptx.pdf&v=CM5lbIzH2kc
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Quieting The Boom
https://www.nasa.gov/wp-content/uploa...https://www.youtube.com/redirect?event=video_description&redir_token=QUFFLUhqa3JCdlRmWFMzQTV0eVk1cEFCblBqcFg5eUI5UXxBQ3Jtc0tsSEdmS3dqTkRwQktqYklFYklsUjB0Yy1uSktOYlFTWFNWODg4LWRhRXItcWgydjF1X1JGZEZkenNpMEdCWDlPV1N6WTVxcjVtajYwTVlKZnY4RVhRTnlaM3EyMm1OdXBMeGx0QV8yWUtnUGx5eDRwMA&q=https://www.nasa.gov/wp-content/uploads/2020/03/quietingtheboom-ebook.pdf&v=CM5lbIzH2kc
Report on the 2018 Experiment over Galveston
https://ntrs.nasa.gov/api/citations/2...https://www.youtube.com/redirect?event=video_description&redir_token=QUFFLUhqa2F4eFlhRDhndXpNLXRucGNfSTZwVU5UeTg1d3xBQ3Jtc0tsUzBLaFBkRVhDTWNWY0t5b2lINVQ0SS1nOHFRM1VmdktIQzU5dF9MUzJmZk5lSGJBNHAwWngxV002ZV9uQ3B6Y1Aza1ExVzRFNllWWEJzV2hBTWVuMklQVy1hR2ZGaHNQMVFaOG9FcE5ncFJrcVhzWQ&q=https://ntrs.nasa.gov/api/citations/20200003223/downloads/20200003223.pdf&v=CM5lbIzH2kc
Falcon 9 Sonic Boom
https://pubs.aip.org/asa/jel/article/...
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Maybe this has been discussed already but I don't understand how there were discussions on here saying Boom wasn't targetting quiet flight but simply using technology advances to be more efficient.

Now out of nowhere they go boomless? Did they change direction, seems they pulled it out of nowhere.
 

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