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Boom Technology Overture M2.2 SST

red admiral

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Nobody says that it's all about CFRP. For example if I take two large extruded or casted body panels and glue them together with high Mega Pascal glue, my part counts just dropped from a hundred to... 3 (two panels plus a tube of glue)...

And then you'll need to rivet those panels together to make it airworthy... or rather demonstrably safe.
 

TomcatViP

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Why?
High Mega Pascal glue joints can have tremendous tear forces (the glue joint can be 100MPa high) and greater joint surface to sustain terrific loads at the end.

The only drawback is cost.
 

Sundog

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Something else to note, is the cruise speed has been dropped from M=2.2 to M=1.7. They said that's a result of the engines required to meet noise requirements. So my guess is, they realized they needed a higher bypass ratio to meet the noise requirements.
 

red admiral

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Why?
High Mega Pascal glue joints can have tremendous tear forces (the glue joint can be 100MPa high) and greater joint surface to sustain terrific loads at the end.

The only drawback is cost.
Cost can be much lower than equivalent mechanically fastened joints. But how do you prove the glued joint is good? This is not sojethingbthats currently been done apart from types that have significant departures from normal manned airfraft safety targets e.g. aerial targets
 

steelpillow

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A while back I saw a CFRP fuselage for a Biz jet which was to have been 20% lighter and cheaper than its aluminium equivalent. Only it didn’t turn out like that and not for the want of a lot of effort. The problem comes when you have to certify the thing you’re designing and the weight just keeps going in. Take for example conductivity, aluminium is and CFRP isn’t. So on the Ali fuse it’s inherently an earth return and lightening screened. But CRFP needs a remarkable amount of metal to provide the same functionality. When the magic -20% figure is banded about its a straightforward ratio of mass specific strength but the problem is designing something that works is anything but straightforward.
Let us not forget LearJet, who pioneered the first all-CFRP commercial airframe, fell foul of exactly this kind of issue, and collapsed penniless. On the other hand, wiser manufacturers in the more traditional markets have been steadily adopting CFRP and do now turn out high-fibre diets, I mean aeroplanes. It can be done, but it is a lot harder to get right than good ol' metal-bashing.

In a former life I was an EMP test engineer with B.Ae. The carbon does conduct in the direction of the fibres. A direct lightning strike causes the nearby resin matrix to evaporate and the fibres poofle up like a bog-brush around the hole. The trick is to design in an electrical path which the discharge current will naturally "prefer", and which avoids the paths of the main structural forces, and then to use hi-tech turkey foil and similar to encourage the current to stay on its preferred path.

The large and long-established corporates took decades to build up the necessary EM capabilities, and hence the ability to produce viable carbon composite airframes. If you do not have a suitably experienced electromagnetics engineer in the design team, your structural engineers will get it badly wrong and have to massively overdesign everything to satisfy the certification inspectors. I suspect that the average bizjet startup is too ignorant, impatient and cash-conscious to build up the necessary solid EM capability.

Even Elon Musk dropped 21th Century composites for plain old steel, to build Starship...
Steel is not a bad aerospace material, it has good strength/weight. The trick is to use it in very thin sections. Its two main problems are corrosion and stiffness. It has been used successfully since the pioneer days, from Junkers to Blohm & Voss to the MiG-25 "Foxbat" to the Starship. For a step-rocket, it spends too little time in damp air for corrosion to be much of a problem, while doubling the structure as a fuel tank leverages the tank pressure to stiffen it like a party balloon.
 
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Archibald

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Let us not forget LearJet, who pioneered the first all-CFRP airframe, fell foul of exactly this kind of issue, and collapsed penniless.

I wondered what you meant there, searched and found this.


Outch ! This plus the C-series... no surprise Bombardier ended with severe troubles, and into Airbus arms.
 

TomcatViP

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Why?
High Mega Pascal glue joints can have tremendous tear forces (the glue joint can be 100MPa high) and greater joint surface to sustain terrific loads at the end.

The only drawback is cost.
Cost can be much lower than equivalent mechanically fastened joints. But how do you prove the glued joint is good? This is not sojethingbthats currently been done apart from types that have significant departures from normal manned airfraft safety targets e.g. aerial targets
Oh it has been done. Particularly with wings. ;)

1622801777904.png

There is only an eight-hour time window from application of the adhesive to when the part must reach the ideal curing temperature.

 

Zoo Tycoon

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BAe 146 wings were adhesively bonded structure and sure there were others in the same timeframe. To the best of my knowledge they never had any significant problems with the bonding. However updates to certification rules have pushed big structures to be bolted together. Whilst I think this is a retrograde step, Boom will have to build a certified structure for their Overture. As the little one is not certified, what they’re doing on this is of no relevance.
 
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Arjen

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United Airlines is moving towards buying 15 Boom Supersonic Overture aircraft.
' once Overture meets United's demanding safety, operating and sustainability requirements '
 
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Grey Havoc

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steelpillow

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updates to certification rules have pushed big structures to be bolted together.
What is the reason for that? Bonded structures have always been around in one form or another and pretty much took over from bolts and rivets through the postwar era. They are mechanically cheaper, lighter and safer as they avoid the stress concentrations (in both work schedule and structure!) inherent in bolt- and rivet-holes.
 
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Reminds me of the joke about the Scotsman who flew with the RAF during the Bliz:

"There were fookers everywhere!"
"Oh, you mean Fokker 190s?"
"No, these fookers were in Messerschmitts!"
Ah, but was the Scotsman drinking Irn Bru? If there were Messerschmitts, they would have to clean it up, sorry, couldn't resist.
 

steelpillow

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Apparently the engines are expected to run on renewable biofuel, though nobody knows how sufficient quantities can be obtained. I am also staggered at how close to Concorde/Tu-144 the latest CAD graphic looks; what price all that vaunted technology advance and sonic boom reduction? See https://www.bbc.co.uk/news/technology-57361193
 

Archibald

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Independantly of that (I plaid guilty for not having been diplomatic),
My goal was to point personal fears of Boom being headed the same way of Aerion
- they have slowed from mach 2.2 to mach 1.7
- for reasons related to engine and noise
- the plane has also grown heavier
- RR will have to design an engine from zero at great expense.
 
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alberchico

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For anyone who wants to know what it takes to put an SST in service, I highly recommend this book. It covers the history of Concorde from inception all the way to its certification process as well as the route proving flights and initial entry into service. Many people at the time considered it to be Europe's equivalent to the Apollo program. I just cannot for the life of me fathom how a startup company can achieve this. Only if a heavyweight firm like Lockheed Martin signed up as a partner do I see them having a chance. That's assuming they can secure the 10 billion needed to put this aircraft in service.
 

Archibald

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For anyone who wants to know what it takes to put an SST in service, I highly recommend this book. It covers the history of Concorde from inception all the way to its certification process as well as the route proving flights and initial entry into service. Many people at the time considered it to be Europe's equivalent to the Apollo program. I just cannot for the life of me fathom how a startup company can achieve this. Only if a heavyweight firm like Lockheed Martin signed up as a partner do I see them having a chance. That's assuming they can secure the 10 billion needed to put this aircraft in service.

Not a bad point per se. When Aerion got Boeing support I got similar feelings and felt they may have assured their future.

I was wrong.

Boom however hopes going around this issue by designing a far smaller airliner: 55 to 75 pax when Concorde maxed at 140.

Technology on paper has progressed a lot and on paper at least this should help making their lives a little easier.
 

sienar

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Something else to note, is the cruise speed has been dropped from M=2.2 to M=1.7. They said that's a result of the engines required to meet noise requirements. So my guess is, they realized they needed a higher bypass ratio to meet the noise requirements.

Its almost like Barnes Wallis was right all those years ago....
 

steelpillow

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Something else to note, is the cruise speed has been dropped from M=2.2 to M=1.7. They said that's a result of the engines required to meet noise requirements. So my guess is, they realized they needed a higher bypass ratio to meet the noise requirements.

Its almost like Barnes Wallis was right all those years ago....
Not sure that Wallis ever banged on about cruise speed, noise and bypass ratio? OR.330, for which he submitted a Swallow design, called for Mach 2 cruise with Mach 3 sprint. I don't think his SST version was intended to cruise any slower or quieter, though I cannot find any performance estimates offhand.
 

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Archibald

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If you say so, I'm ready to accept it.

There was one British early SST concept which cruise speed was Mach 1.15, but can't remember which constructor / project number it was.
 

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If you say so, I'm ready to accept it.

There was one British early SST concept which cruise speed was Mach 1.15, but can't remember which constructor / project number it was.
Take your pick for the lower-end of the speed range:
AWA AW.P13 - Mach 1.2, 1956
Bristol Type 198 - started at Mach 1.3 with M-wing and ended up a Mach 1.8 delta, 1956
DH DH.130 - Mach 1.15 cruising with VG wings, 150 economy passengers, 2,350nm range, with Super Conway engines - this design morphed into the VG-wing HS.1101 from the Kingston Advanced Projects group in the 1960s, Mach 1.15 cruise, 160 passengers, 2,500nm range and no ground sonic boom
HP H.P.128 - Mach 1.15 cruising without ground sonic boom, 90-125 passengers, designed for 500 mile stage lengths, 3x Spey, 1962-64

The Supersonic Transport Aircraft Committee in 1956 wanted studies of medium-range 100-seat Mach 1.2 and longer-range 150-seat Mach 1.8 airliners, which is why the the companies split their efforts and the larger type won out to become Concorde. Barnes Wallis at Vickers was very much in the high-speed very long-range camp beyond the STAC types but quite a few manufacturers did tinker with Mach 2.2-3 designs.
But it seems that de Havilland and Handley Page by the early 1960s were both thinking of Mach 1.15 cruise with off-the-shelf engines and no boom at ground level.
 

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Scepticism is fine, but Boom do appear to be building actual hardware so lets give them a pass for now.
Boom is going about this the correct way, building a sub-scale demonstrator air vehicle to prove out their design, smart, lower risk. Business jets in general are luxury items but they also can make very nice special mission aircraft as well, a s-sonic special mission aircraft could offer significant capabilities as an example. I think supersonic biz jets will be a reality in the near future when boom mitigation/reduction is proved out. Aerion bit off more than they could chew, going right into a full-scale aircraft and not to mention big risk for the investors including their statement mentioning a potential Mach 4 aircraft, not smart at all. Also, smacked of Kistler Rocketplane, Kistler duped even some of the big guys into their funding black hole, big on promise but delivered nothing.
 

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[Boeing CEO Dave Calhoun] addressed United Airlines’ decision to order fifteen 65- to 88-seat supersonic Overture airliners from startup Boom Supersonic (financial terms not released), scheduled to enter passenger service in 2029. “I applaud the decision by [CEO] Scott [Kirby] and the team at United to go after technologies like these. If the technology comes out and comes to bear in the marketplace, in some time frame that matters, ‘congratulations.’ They’ll be at the front end of that. And I’m all for that. We don’t have to compete on every single form of aircraft.”

(double posting here)

 

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Did Overture get bigger or did they decide to make the seats smaller? Initial descriptions refer to it as a 55-seat aircraft but now we're hearing 65-88. Is that just down to shorter seat pitch or did the cabin get longer at some point?
 

yasotay

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Did Overture get bigger or did they decide to make the seats smaller? Initial descriptions refer to it as a 55-seat aircraft but now we're hearing 65-88. Is that just down to shorter seat pitch or did the cabin get longer at some point?
Since the flights are so short, you don't have to sit down. Tram handhold on the ceiling should suffice.
 

djfawcett

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Did Overture get bigger or did they decide to make the seats smaller? Initial descriptions refer to it as a 55-seat aircraft but now we're hearing 65-88. Is that just down to shorter seat pitch or did the cabin get longer at some point?
The overall length has grown from 170 ft to 205 ft. The foot print is getting real close to the size of the Concorde.
 

TomS

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Did Overture get bigger or did they decide to make the seats smaller? Initial descriptions refer to it as a 55-seat aircraft but now we're hearing 65-88. Is that just down to shorter seat pitch or did the cabin get longer at some point?
The overall length has grown from 170 ft to 205 ft. The foot print is getting real close to the size of the Concorde.

Interesting. So it isn't just seat pitch games.

I suspect that has to be related to United. If they want more seats, that's a major pressure.
 

TomcatViP

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Don't forget that Mach wave shaping tends to exacerbate any increase in length or cabin diameter (extended nose and tail cone).

It seems also logical that if they had to decrease the maximum mach, it was most probably for T.O and landing constraints (more wing surface was needed to decrease speeds or/and noise), something that would open the door for more passengers.
 

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