The Anonymous Widower

United Airlines Eyes A Supersonic Future With Deal To Buy Boom’s Overture Jets

The title of this post, is the same as that of this article on The Times.

Some may feel that the future of supersonic aviation is about as rosy, as an empty glass of tap water.

But!

  • A flight across the Atlantic in three-and-a-half hours, as is promised by the Boom Overture, is below the four-hour travel limit, where average people start to get anxious about being banged up!
  • Not for nothing do UK train companies want to get London and Edinburgh services below, the magic four-hour time.
  • Technology will get better to reduce the noise and carbon emissions of all aircraft and not just supersonic ones!

I don’t put it outside the genius of engineers to by 2050, be able to create a supersonic, almost noise-free aircraft.

I do have a few thoughts about the Boom Overture.

A Comparison With Concorde

These are comparisons of the Boom Overture to Concorde.

  • Engines – Three as opposed to four.
  • Length – Similar
  • Wingspan – 71 % of Concorde
  • Passengers – 75 % of Concorde

It’s almost as if the Boom Overture is a three-quarter scale model of Concorde.

The Wing/Airframe

When I left Liverpool University in 1968, I wasn’t totally sure, what I wanted to do. So I visited a lot of engineering and aerospace companies including both BAC and Hawker Siddeley. Including my own University, I must have visited about four or five large wind tunnels in that period and every one had a Concorde-like model for the wind tunnel.

Every company had their own ideas on what a supersonic wing, should look like.

And surprise-surprise they were all very similar!

Take the advertising off Formula One cars and paint them all silver and very few could tell them apart.

Aerodynamics defines the shape so strongly, they all look the same.

It’s the same with supersonic aircraft and I’m not surprised that wing planform of the Boom Overture appears to be similar to Concorde, but narrower.

Perhaps the more dart-like shape significantly reduces the drag? It should be noted that drag is proportional to cross-sectional area.

In Concorde’s Wikipedia entry there is a section called Development, which explains how the Royal Aircraft Establishment developed the slender delta wing planform, used by Concorde and now likely to be used by Boom.

Although, it would be different inside the wing, as Concorde was mainly made from metal and the Overture is a composite aircraft.

Perhaps composite construction helps with creating the perfect aerodynamic shape. I don’t have any experience of composites, but they surely mean more aerodynamic shapes and they are regularly used for airframes.

This page on the Heritage Concorde web site gives details of the airframe production materials.

I suspect that Concorde was a nightmare to build, but that the challenge helped develop a large number of machining and fabrication techniques.

The Fuselage

As I said earlier, the length of the plane is similar to Concorde, but the wingspan is 29 % smaller and the number of passengers is around 25 % less.

But if you look at the picture of the aircraft in the Times article, where it is emerging from the hangar, it’s almost as if the fuselage has a square cross section than Concorde.

I wonder about this square cross section. I remember an interview on the radio with Barnes Wallis, where he talked about his latest idea for a fast supersonic aircraft capable of flying between the UK and Australia.

This paragraph is from Barnes Wallis’s Wikipedia entry.

In the late 1950s, Wallis gave a lecture entitled “The strength of England” at Eton College, and continued to deliver versions of the talk into the early 1970s, presenting technology and automation as a way to restore Britain’s dominance. He advocated nuclear-powered cargo submarines as a means of making Britain immune to future embargoes, and to make it a global trading power. He complained of the loss of aircraft design to the US, and suggested that Britain could dominate air travel by developing a small supersonic airliner capable of short take-off and landing.

It sounds to me that he would have been a Brexiteer.

Could this supersonic airliner, be what I heard him talking about?

I distinctly remember that he was advocating a fuselage with a square cross section for supersonic flight.

  • It would have given more space inside for passengers.
  • Concorde was a bit pokey with small windows!
  • The picture in The Times of the interior of the Boom Overture is certainly spacious.

Have Boom, been looking through Barnes Wallis’s ideas?

One quote I heard Barnes Wallis say, in an interview with Chris Brasher was this.

There is no greater thrill in life, than proving something is impossible and then showing how it can be done.

Boom may not have been able to develop a small supersonic airliner capable of short take-off and landing, but it does sound, they’ve developed a smaller supersonic airliner capable of shorter take-off and landing.

The Engines

In the Boom Overture’s Wikipedia entry there is a section called Engines, where this is the last sentence.

In July 2020, the company announced that it had entered into an agreement with Rolls-Royce to collaborate on engine development.

As Rolls-Royce built the engines for Concorde, they probably have some experience locked away.

The design of the Olympus 593 engines for Concorde wasn’t simple.

  • The engines were based on an Olympus engine used in aircraft like the Avro Vulcan and the TSR-2.
  • The engines were fitted with afterburners, as the extra thrust was needed for take-off.
  • According to Wikipedia the engines had a high thermal efficiency in supersonic cruise.
  • According to Wikipedia, there was an engine without afterburning for a longer range Concorde under development.

Over the years, there have been various proposals for supersonic aircraft, in military, commercial and business fields, so I suspect Rolls-Royce have done significant work in powering supersonic flight.

But then other engine companies would have gone down similar routes!

Rolls-Royce though probably have all the data on the engine ideas for Concorde that failed.

I wouldn’t be surprised, if one of the major aero-engine companies has a solution to the powerplant for the Boom Overture, based on the chase for supersonic speeds forty and fifty years ago.

But Rolls-Royce because of the Concorde experience could be closer to a successful development.

So I think signing with Rolls-Royce could be a very sensible move.

The Afterburners

The Wikipedia entry for the Boom Overture says this about afterburners.

Boom wants to use moderate bypass turbofans without afterburners, unlike Concorde’s Rolls-Royce/Snecma Olympus.

Could that be one piece of complication, that improvements in technology has eliminated?

The Engine Intakes

The Wikipedia entry for the Olympus 593 engines has a section called Intakes.

They were thought to be clever in the 1960s, but they just look complicated to me, with all my extra experience.

The intakes seem to have used very comprehensive digital control systems, but these days controls like these will be even more comprehensive and a lot more sophisticated, as computing has moved on.

I very much feel that if the Boom Overture needed sophisticated variable-geometry engine intakes like Concorde, we have the knowledge to create them and the computer expertise to make them act as needed.

The Exhaust Nozzle

The Wikipedia entry for the Olympus 593 engines has a section called Exhaust Nozzle.

These too are complicated and a lot of what I said for the intakes, would apply to the nozzles.

The Fuel

The Wikipedia entry for the Boom Overture says

The aircraft is intended to run on Sustainable Aviation Fuel.

It is likely, that Sustainable Aviation Fuel will be used for commercial aviation until there is a significant move to hydrogen.

  • In the UK, a company called Altalto is building a large plant to make the fuel at Immingham from household and industrial waste.
  • One idea being pursued by some companies is to create the fuel from used disposable nappies.
  • Wikipedia indicates that the fuel could cut CO2 emissions by between 20-98%.
  • Altalto is backed by British Airways and Velocys, who are a spin-out from Oxford University.

There is certainly a lot of money and technology being thrown behind Sustainable Aviation Fuel to make it a net-zero alternative for the powering of aircraft.

The Noise

This Youtube video shows Concorde’s last take-off from New York.

It was certainly a noisy aircraft.

  • Concorde’s engines had afterburners.
  • It also needed a long take-off run, so it made more noise on the ground.
  • It used to take off with a high angle of attack with the nose high.

All of these factors would have increased real and perceived noise levels.

I feel that if the Boom Overture is going to have significantly lower noise levels than Concorde, then its design will need to be radically different.

The lack of afterburners will make some difference.

It carries only about 75 % of the passengers of Concorde.

It is roughly, the same length as Concorde, but the wingspan is nearly thirty percent smaller.

To be continued…

 

 

June 6, 2021 - Posted by | Design, Hydrogen, Transport | , , , , , , , , ,

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