By Bjorn Fehrm
November 17, 2016, ©. Leeham Co: Boom Technology plans to do a 45-seat airliner for supersonic passenger traffic with service entry by 2023. Richard Branson’s Virgin Atlantic has already placed an optional order for 10 units of the aircraft.
The idea is to fly 45 business class passengers between New York and London in 3 hours and 25 minutes. This means the Boom Super Sonic Transport shall be 10% faster than the Aerospatiale/BAC Concorde.
What makes the Boom SST succeed where the Concorde failed?
We will look at the challenges that Concorde had and see how Boom SST plans to attack them. We will also discuss what the chances are that Boom SST can master these challenges.
Proof of concept
The company rolled out an engineering mock-up of a one third proof of concept aircraft this week, Figure 2. Plans are to fly the smaller “Baby Boom” before the end of 2017 with the help of three GE J85 turbojets.
The idea is to prove the low speed handling at the company’s Centennial airport Denver (CO) location with later supersonic flights to be made at Edwards Air Force Base. The Spaceship Company (TSC), the Mojave-based manufacturing arm of Branson’s Virgin Galactic will assist with the flight testing.
The Boom SST will only focus on the business traveler. For a normal long range aircraft departure from New York or London, Boom argues that around 40-50 of the passengers are full fare Business Class passengers. The rest of the passengers for the aircraft are lower yield economy passengers. Boom will now offer the full fare business passenger between New York and London (or other suitable city pairs) a flight which halves the flight time.
A typical business ticket between New York and London cost around $5,000 round trip, argues Boom, and this will make the cost of operating the Boom SST a viable business case. By combining 45 seats and a high frequency (due to the short flight time), the problem of filling a 100-seat Concorde with the resulting lower departure frequency should be avoided.
Boom has got some points right in the business discussion. But it all depends on the per-seat costs of the flight. Flights to the US market can only be made over water as supersonic passenger transport flights are forbidden over US land territory.
So, there are also few city pairs that are viable within the range of the aircraft, which is 4,500nm. The unrefueled range makes trans-Oceanic flights problematic. The intra-Asia market could work with destination like Singapore-Tokyo (3,000nm) or Singapore-Sydney (3,300nm).
Can Boom SST succeed where Concorde failed?
If Boom Technology has some points around the business case, the larger challenge is the technical realization of a supersonic passenger aircraft which can achieve the specification that Boom outlines.
Boom plans an aircraft that will fly 4,500nm at Mach 2.2, 10% further and faster than the Concorde. And it will do that at an operating cost that will make the operation of the aircraft profitable.
Let’s examine what’s involved and what technical challenges needs to be mastered.
Low drag needed
The first challenge is to find an aircraft configuration that gives the low supersonic drag needed for economical flight. At the same time, takeoff and landing speeds must allow operation from normal international airport’s runways.
Boom chose to go a conventional way. There is no low sonic boom or laminar supersonic flow technology as with competing projects (QSST and Aerion biz. Jet). The aircraft configuration is a 75% copy of the Concorde when one looks at the configuration and the data, Figure 3.
The figure is created by taking the Boom data and renderings and comparing it to the Concorde. The Boom is an almost true 75% version of the Concorde configuration. Lately a third engine has been added in the tail (not shown in our drawing) to allow for ETOPS-free routes with up to 180min diversion time.
Having flown a predecessor to this configuration (the compound Delta SAAB Draken), I know the advantages and drawbacks by heart. The configuration is well known and gives very good transonic and supersonic characteristics. The low speed regime is challenging however.
Engines are always the key
A compound Delta has a high drag at low speed due to the low aspect ratio of the wing (around 1.5 compared to 8-9 for a normal airliner). This requires a lot of thrust from the engines at take-off and landing. The Concorde engines had afterburners for a takeoff thrust boost and later for the push through the sound barrier and climb to cruise altitude of around 50,000ft. At cruise, the straight jet Olympus engines were operated without the afterburners.
Boom says they will manage this envelope with moderate bypass turbofans without afterburners. Such engines are not available in the market. The lack of suitable engines is a major culprit for all present supersonic transport projects.
An engine for supersonic flight must have a high jet speed leaving the engine at supersonic flight. This is not the case for today’s airliner engines. The only high jet engines are military fighter engines, but these do not have the fuel economy nor the reliability required for civil transport operation.
The development of a suitable transport engine is a multibillion dollar business and no engine manufacturer can do such an investment based on 10 optional aircraft for Virgin Atlantic. The engine is also where the most advanced supersonic business jet project is struggling, the Aerion AS2. It has still not announced which engine it will use after years of discussions with engine companies.
Boom says they have identified existing cores that could be used, but the complete low pressure system (fan, low pressure compressor and turbine plus all the major castings) would have to be developed and the finished engine need to go through testing and certification.
The engine is perhaps the hardest nut projects like Boom SST must crack. Once the engine is fixed, there remains other challenges. One is the nose up attitude that a compound Delta needs to have for attaining a suitable landing speed. Concorde and Tupolev 144 used droop noses.
Boom seems to do nothing to improve the “over the nose” visibility. It could pose certification problems dependent on their proposed solution.
Another major problem area is the noise a SST aircraft/engine combination generate. As mentioned an SST engine must be a high jet speed engine (it must achieve about three times the jet speed of a conventional engine).
The speed of the jet leaving the engine is the primary source of noise. A high jet speed engine is noisy. Boom say they can meet future regulations but it acknowledges that it’s a challenge. The risk is that engine noise and performance can be contradictory for an SST project; achieving the one can mean not achieving the other.
An additional problem will be the fuel consumption of the aircraft. Aerodynamic data for the compound Delta chosen is known, as is the fuel economy of the type of engine which can be achieved. The fuel consumption per seat and nautical mile with be around three times that of a modern twin aisle airliner flying between London and New York.
Cutting the travel time in half between London and New York is an attractive proposition. With available technology, it seems to be achievable at the cost of three times higher fuel consumption per seat and nautical mile.
For a business class passenger, that might still be an acceptable price to pay for the shorter travel time. But to get to the cost per seat of fuel and other factors that one can project for a SST airliner, the Boom team must crack a number of hard nuts. That the company should be able to do that to a certification by 2023 is unrealistic. The question is not when the certification will be probable, rather will Boom succeed at all?
Airframe construction and certification will be tough, but finding a suitable engine partner that is prepared to develop the needed engine will be even harder. All other supersonic transport projects have so far failed at the engine challenge, except for Concorde. The Tupolev 144 SST was killed by engines that had to run with afterburner at cruise when the base engine thrust was not sufficient for cruise at Mach 2.0.
Three engine would reduce the required power per engine significantly over a dual engine configuration.
If X is the thrust is required to meet TO V1, V2 requirements, the engines of a twin each have X thrust, while those of a trijet only need to be 0.5X.
Concorde had 4x 38k lbs installed, so needed around 114k lbs. If this aircraft needs half and is a tri jet, those engines would required around 29k lbs per engine.
Similar thrust to a CFM, but entire different. Here’s a schematic how a Concorde engine airflow & cooling worked.
The turbofan NK-144 engines were a provisional installation
due to unavailability of a fitting turbojet type at the time.
The final Tu-144-D model sported RD-36-51 engines.
These allowed supercruise.
What Tupolev managed quite well was low speed capabilities.
IMU the Soviet Union had no sensible use for supersonic transport. ( neither did the West, really, but squandering resources is an established way to show off wealth.
Booms design appears to be a direct Concorde copy http://www.concordesst.com/concordeb.html that hopes to compensate losses from scaling via improved engine sfc performance. not a simple task.
Would you be able to provide some insight in your series of the turbofans on the differences between normal jet engines and supersonic ones? Like how are the higher speeds achieved, where does the higher fuel burn come from etc. That would be very interesting to read.
the best is to read this article which describes how thrust is generated and why you need engines with different exhaust speeds and what the exhaust speed does to efficiency and thrust.
Branson is being used to pitch funding and claimed feasibility. Good luck to both.
A 3 hours 25 minutes flight from Heathrow to New-york may look like a good business case. But if the costumer have to take 2 or 3 hours to travel from Downton to the airport. Jumping into the A318 or the CS100 from the City airport become a good alternative then.
The thing that really made Concorde work was the ground arrangements. None of this check-in 3 hours ahead lark – turn up with 20mins to go at the dedicated terminal facilities. On arrival, none of the nonesense of queuing up at immigration and baggage reclaim, dedicated facilities were used for both of those too.
Result – I reckon the dedicated ground arrangements knocked a good 3, 4 hours off the total journey time too. So you were about 6 or 7 hours ahead of someone who’d gone by 747 LHR JFK – a massive time saver.
Does BA run that A318 from City to JFK in the same way they ran Concorde, with dedicated ground arrangements? If so, then Baby Boom is looking at beating BA’s A318 total journey time by only 2 or 3 hours if flown from Heathrow compared to the A318 from City (assuming you’re starting from the middle of London). And there’d have to be dedicated ground facilities at Heathrow and JFK for it to achieve that, otherwise it’d be slower overall!
Anyway, forget all that. I hope it gets built!
2-3h from Central London to LHR? Heathrow Express does the run from Paddington to LHR in 15 minutes. Combine that with some dedicated concierge service at either end, and you can get from Central London to the gate in well less than an hour.
But I agree that ground arrangements need to be top-notch in order for this to show real time savings.
Westbound I would prefer a sleeper seat & don’t wake me up after 4 hours in the middle of the night.
And Eastbound TATL you’re ok anyway.
Blinded by technology / enthousiasm?
And your sleeper seat will cost you another 5K!
But with SST you could take an early-morning flight from JFK, still get to London for a late afternoon meeting and business dinner, and then catch a late-night return flight to JFK.
I think the business case can work, if the technology can.
Given the debacle with delays and changing propellant choice with Space Ship 2, I cant see this working out at least in that time frame. Something like an A321 neo is so far ahead in terms of the engines that are available to it. Boom would be bust. Agree with Andre Allard.
An engine for supersonic flight must have a high jet speed leaving the engine at supersonic flight. This is not the case for today’s airliner engines. The only high jet engines are military fighter engines, but these do not have the fuel economy nor the reliability required for civil transport operation
Could the GE’s research into more flexible and efficient military engines come in here?
But what you need is a convergent / divergent nozzle.
first you constrict flow to increase speed than you expand …
The Concode ‘B’ model which was supposed to follow the initial production version had improvements to the Olympus engines to remove the need for afterburners ( only used on takeoff and transonic flight)
‘modification consists of replacing the low-pressure compressor by a compressor with increased diameter and the low pressure turbine assembly by a two-stage turbine. The installation of a discharge system to increase the margin of air flow through the engine would result in an increase in air flow which reaches 25 % on takeoff and 35 % during approach.’
At supersonic cruise flight the engines were only providing 10,000 lb thrust. Not sure if no afterburner but supercruise means the convergent/divergent nozzle is required
IMU the adaptive cycle stuff is designed to enable low sfc for lingering while allowing high thrust for a dash.
Problem is a Supersonic Transport is in contiuous dash mode so to speak.
Same as any of the CODOG, CODAG, whatnot arrangements of diesel and gasturbine propulsion do not make much sense for a high speed freighter.
( see the early gas turbine driven container ships of Euroliner series. https://de.wikipedia.org/wiki/Gasturbinenschiff#Euroliner-Containerschiffe )
I just don’t see the commercial business case for supersonic east coast to Europe panning out. Bizjet business case is more clear cut if you can get it to take off and land at small secondary airports (5000ft or smaller runways which this plane won’t be able to do). vanity and extreme wealth will go a long way in the bizjet world.
at the end of the day, you still need to drive an hour to the airport, be there an hour and a half before the flight, wait half an hour for your luggage, wait half an hour at customs, drive an hour into the city. you are really taking only talking about a 25-30% reduction in overall travel time. (from 10.5ish to 7.5ish). and in exchange you get to pay a lot more money and create a lot more pollution.
plus the reality that the engine alone is a $1B minimum development exercise (all new LP section on a LEAP or PW GTF core).
this whole project seems like the least viable of the currently active SSBJ/SSCJ projects and the others don’t look very viable either.
The target customers for this kind of service will generally not be checking luggage, to be sure.
I did a pretty fast read of the article but didn’t see any discussion of how much it would cost to build this plane, how much it would sell for, and how many they would need to sell, to recoup development costs.
I”m not sure Boom Technology have reliable estimates of the development costs yet. As said they have some pretty hard nuts to crack and until you have found how to get e.g. your engines and what that will cost in money and time you can’t really estimate the development costs.
Boom for sure has estimates but looking at the 30-50 people they have on the pay list and 2023 for certification I would not give much for their estimates. They shall have quoted a $200m list price for the aircraft.
Costs are unknown apparently.
It’s a commercial airliner with a lot of new engine, advanced materials, R&D, supply chain, systems, production facilities, more then a regular passenger aircraft. So maybe the investment is 1.5 x a new NB.
I would think a new NB these days easily requires $6-8 billion investment, if everything goes right, and take about 7-8 years.
So this machine would require around 10 Billion and 10 years? If someone promises anything else, be cautious, he’s after the money. An assembly is an assembly, a production line a production line, an fte an fte & the EASA/FAA take no short cuts on quality procedures, reliability and flight safety.
A major government pushing in billions seems required, specially because the business case is going nowhere at this stage.
What about cabin exit ? Aren’t they supposed to ba at each end of the cabin? (FAR25.807 §f (3) )
Another problem there…
Naming this embryonic project as Boom is highly ill thought through & one questions if as much consideration has been applied to the concept. With so many technical hurdles to jump it smacks of another ill conceived dream that throughout aeronautical history have ultimately disappeared into the ether.
Setting aside the technical issues, it’s reasonable to question the business case. Should the project ever reach fruition I as many would struggle to see the projects success within such a restricted routing market.
We will see after the test flights. RR could fairly easy mix a scaled down Olympus with Trent XWB hot section hardware and get it certified as an Olympus derivative. The increased heat and pressure entering the Engine after an effecitve supersonic engine inlet for hours was solved on the Olympus. The Concorde had to slow down at cruise to below M2.2 due to wing l.e. temperatures and the alumium alloy used. Boom looks like a 10-15 year program and costing $20-50bn to get certified if starting from scratch, there might be some military research program that is the origin to this program cutting the cost and time to certification?
Baby Boom = LG (Life is Good) ! Take-Off from London at 10h:00 local time, arrival New York at 08h:00 local time, ideal for a full workday somewhere in Manhattan … then you dine chez Pierre or attend a Broadway performance, whereupon you catch the midnight Boom-line departure and again you arrive in London at 08h:00 local time, fresh awake for a full workday in the City : this is a winner ! You can’t expect a better service than with this Baby-Boom marvel ?!
“midnight Boom-line departure and again you arrive in London at 08h:00 local time, fresh awake for a full workday in the City : this is a winner !”
I missing the “fresh awake” part after a 2-3 hr sleep in a seat thing. 5-6 hrs in a flat bed would be better. Unless the Baby Boom is much cheaper.
I have a problem with the statement that Concorde was “unsuccessful”. Granted it was not the success the originators envisaged, but it flew and flew well. I was lucky enough to fly from New York to London in one once. That experience remains in my memory even today. During that flight, we looked down at a 747 that appeared to stand still in the sky as we flew past.
No sir, the safety record and passenger experience of that service is unsurpassed. Mildly successful, I say. Just as old jets are currently being withdrawn from service due to high fuel costs, it is no different to Concorde’s withdrawal.
Did the Boom people draw up their business plan on the back of a Jackie Collins novel? Their glossy US-UK business travel market belongs in another age. This technologically impossible and financially unachievable never-jet will be ready just in time to flit between the ashes of Trump’s America and Brexit Britain, as the last lights are switched off. Good luck filling those uncomfortable seats.
It is a daring project that need loads of money and a certified supersonic commercial engine. They might be lucky if RR promises Sir Richard Branson a certified engine and Dassault want to get on and finish the design and certify it. Still it will take 10-15 years and cost as many $bn. Maybe The Donald will order it as a new supersonic Air Force One:1 with the USAF paying for military certification, just replace RR with PWA and Dassault with Gulfstream/Boeing St. Louis.
Layman, I would say that Concorde was both a commercial success for BA (marketing & US route) and a technological success. This revisionist history that it was a commercial disaster is nonsense. It is true that Air France never made any money on their route. But it is also true that BA offered to buy out Air France (engines + planes) and Air France refused. For obvious, to them, reasons.
The big question for you to check into is the price AF and BA paid for their Concordes. Was it realistic, or low for political reasons?
“British Airways predecessors (BOAC) paid the manufacturers more than £155 million for the Concorde fleet.”
Boac initially had a fleet of 7 ( last delivered in 1980 )
that is £22+ million per airframe. @ 1978 exhange rate : $40.95m
Now: what year pound? 🙂
For the purchase timeframe that is not cheap.
( 1 pound sterling was 7..8 DMark, remember that from early travels )
Thanks for the info. However, as with all data numbers are meaningless without context. Therefore we would have to access the cost of similar high end planes of the period to arrive at objectivity.
You should also bear in mind that BA spend many millions upgrading their fleet shortly before the “joint” decision was made to discontinue the Concorde service, does this sound like the act of a company that is not happy to continue the operation? I would also mention that this cost, amortised over the fleet duration seems small in any event. However, again running costs/comparative running costs would have to be taken into account, on one side of the equation.
On the other side of the equation, I believe it was mentioned recently by another contributor, that 60% of average airline profits are generated by business/1st class passengers. Concorde was a 1st class only service, which also generated huge marketing benefits for BA, amongst its target premium flyers, which rivals, apart from Air France, were not able to match.
Maybe Scott has some numbers from around that time? 767 numbers I saw are from 2016, 707 numbers from 1957. not a good fit.
premium seats may present a significant part of profits but they need the “tween decks” seats to provide for cost reduction from scaling.
“The development costs of Concorde were around £1.134 billion, which was funded by the UK and French governments. The cost to build the 16 production Concordes was £654 million of which £278 million was recovered through sales returns (this included spares, technical support, etc.). This debt was also funded by the 2 governments. ”
This and more info from: http://www.concordesst.com/faq.html
cost recovery per item and sunk devel cost seems to compare to the 787.
Difference: States paid up front where for the 787 payment via tax gifts is made over a longer period. 🙂
The question is did the price AF and BA paid for the Concorde reflect much of the development costs.
Again, does the money paid for 787 reflect the development cost?
The expectation was to sell more and that development would have been less costly.
What good is a glass dagger
Note the similar LE configuration, there’s a reason the Concorde used that, technical papers are available on the Internet.
I agree with the suggestion that this would appear to be a micky mouse organisation, and not surprised Branson has leant his name, since options cost nothing (without product delivery). With no realistic engine strategy this is a no go. Normal commercial engines will not do the trick, you just don’t bolt on more engines to increase speed! There is a reason Concorde used a fighter jet engine. There is also a reason that commercial planes with four engines have fallen heavily out of favour in view of two engine planes. The engine is the most expensive part of the plane, to suggest you would have three instead of two or even one, for a small business jet makes no sense, especially as the weight of an engine and extra petrol brings diminishing returns.
Figuring out the actual cost and selling price of Concorde takes some effort, I haven’t done it.
Compounding the task are anomalies like selling two of them for one pound each _but_ as part of a large deal.
Along the way the UK government sold its interest in the IP to BA, perhaps writing off some costs in the process (I forget what the French government did).
Airbus Group – didn’t Boeing have severe problems delivering airplanes because of shortcomings of suppliers of cabin furnishings?
ITAR/EAR sure seems to be a mess. Two examples:
– arcane rules such as needing export approval for a large food mixing device, because it might be used to mix rocket fuel.
– ignorant bureaucrats trying to administer technology.
And game playing, such as what UTC was accused of for an engine to be provided for a Communist Chinese project (accusation of not being forthright about the application, plus unrealistic rules about civilian versus military application).
Please check the definition of the word “culprit”.
As a former airline employee, (UAL from 1966 to 1980), I took full use of my employee travel benefits to attend both the Paris Air and Farnborough Air Shows so many times, I actually became fairly well aquainted with many of the BAC staff assigned to airshow duty, indeed, to the extent, as to be extended an invitation to the final assembly plant at Filton, after attending Farnborough, the next year, which, to say the least, I accepted. A high point of my life, and lead me to learn, first hand that much of the mythology about the Concorde was just that. MYTH!!! The aircraft had the same “mileage” as a first gen subsonic B-707 or DC-8, with either using JT-4 enginges, with the noise not that much different either. What actually killed that bird was the rapid, and unforeseeable, rise in jet fuel costs, due to shifting political changes in the Middle East, and THAT’S ALL!! In any case, it was a grand adventure, and the effort for a successor of any kind doomed to be mooted by the vast improvements in electronic communications making much of business travel, the intended market, unnecessary, especially when one can video conference with someone on the other side of the globe, FAX the documents to be signed, and, rather than overnighting at a hotel, and the end of the day, just drive home to one’s family. In short, it was not economics, nor environmental concerns that have doomed high speed commercial travel forever, but “Moore’s Law”, declaring, as it has, a literal DOUBLING(!!) of computer capability every two years, if not sooner! For those who have not noticed, this is also why there has also been no increase in military aircraft speeds in the last five decades either, since nothing, be it a Concorde or a Blackbird, that must actually move from “point-A” to “point-B” has even the slightest chance of DOUBLING(!!!) its flight speed every 24 months to match the speed of computers, be they providing flat-screen conference calls in the boardroom, or fire control solutions in the nose of a Mig-31 or Su-35. Oh, and BTW, Moore’s Law has since been exposed as an… UNDERSTATEMENT!!! The actual re-doubling is more like every 18 months!!
If you have a skilled specialist surgeon or a technical expert that can solve a problem to get a plant running again you’ll want to put him or her on an SST. This will be popular. We are now in a global market place.
The takeoff/landing visibility problem can be addressed with cameras and screens; much simpler and lighter than a drooping nose.
The premise that Concorde ‘failed’ must be clarified.
As a moneymaking i.e. profitable aircraft, it in fact succeeded for more than 2 decades. BA ran a consistently profitable operation with Concorde following the establishment of the Concorde Division (a stand-alone business unit) in 1982 even with tickets priced just 20% more than First Class.
As an operational aircraft type for BA, it was demonstrably a success (i.e. its Revenue per Available Seat Mile (RASM) exceeded its Cost per Available Seat Mile CASM) and remained profitable until the worldwide traffic decline post 9/11.
If we are talking about a production run profit (i.e. design/development cost vs sales) then it was not a success and this is the case for a number of commercial aircraft like the DC-10/L1011
The reasons for sales failure are multiple and more to do with US politics, the dramatic increase in fuel costs following the 1970s fuel crisis, and the imposed limitation of ‘no supersonic flight over’ land which was not in existence when Concorde was designed and can hardly be blamed on the designers.
That Concorde could remain profitable for so long, proves the concept but this restriction still exists for any SST and Boom will be no different.
Higher subsonic flight over land doesn’t work either. Boeing’s failure with the Sonic Cruiser was predictable as Mach 0.92 -95 flight sits right up against the Mach drag curve, so this won’t work for Boom as fuel burn is too high.
It remains to be seen if Boom will go the way of Aerion.
I would love to see another SST in my lifetime but until someone works out how to make a no-boom SST (i.e. alter the laws of physics) it will suffer the same restrictions that prevented a wider market for Concorde.
The key reason the Concorde was operationally profitable is the governments absorbed the capital costs, relieving the airlines of actually paying for the airplanes.
Hi Scott, that certainly would have had some impact on how much profit the aircraft made but the proposition is more complicated than it looks.
Douglas and Lockheed didn’t make made the airline customers pay for the short production run of the DC-10 and L1011. They charged an acceptable market price for the aircraft and absorbed the loss as did Airbus for the A380, so to expect BAC/Aerospatiale to somehow include the design and production cost in the purchase price of Concorde is not close to reality.
Many more Concordes (90+) were ordered but unforeseen external factors caused these to be cancelled. Had these factors not emerged it is likely that more still would have been ordered lowering purchase costs.
It was never going to be produced in large numbers (a la B-737) as it was designed for a specific role and the purchase prices would have reflected this.
Having said that, given a realistic purchase cost for the time and the consistent profitability of the aircraft over more than 2 decades, would have been profitable even if a purchase cost was included.
Deciding on how to amortise design and production costs for a specific type can however, be an iffy proposition as you get into murky areas such as the US Govt effectively paying for the design, production and development of the B-707 by commissioning and purchasing over 800 of the KC-135 relieving Boeing of most of the cost of doing so..
Boeing also received enormous sums from the US Govt to design and build the B-2707 and it has been reported that the overall spend exceeded the Concorde program and yet did not produce a single aircraft.
Best to judge Concorde on a fair basis rather than an artificial one.