Engineering:Boom Technology Overture

Short description: Proposed supersonic transport aircraft

Overture
Role	Supersonic transport
National origin	United States
Manufacturer	Boom Technology
Introduction	2025–2027

The Boom Technology Overture is a Mach 2.2 (1,300 kn; 2,300 km/h), 55-passenger supersonic transport with 4,500 nmi (8,300 km) of range, which is proposed to be introduced in 2025–2027 by Boom Technology. With 500 viable routes, there could be a market for 1,000 supersonic airliners with business class fares. It had gathered 76 commitments by December 2017. It would keep the delta wing configuration of Concorde but would be built with composite materials. It would be powered by three dry 15,000–20,000 lbf (67–89 kN) turbofans, a derivative or a clean-sheet design were to be selected in 2019.

Market

Five hundred daily routes would be viable: at Mach 2.2 over water, New York City to London would be 3 hours and 15 minutes apart; Miami and Santiago, Chile would be 3 hours and 48 minutes apart. With 4,500 nmi (8,300 km) of range, transpacific flights would require a refueling stop: San Francisco and Tokyo would be 5 hours and 30 minutes apart; Los Angeles and Sydney would be 6 hours and 45 minutes apart. There could be a market for 1,000 supersonic airliners by 2035. Boom targets a $200 million price, not discounted and excluding options and interior, in 2016 dollars: less expensive than premium available seat miles in a subsonic wide-body aircraft. The Boom factory will be sized to assemble up to 100 aircraft per year for a 1,000 to 2,000 aircraft potential market over 10 years.

Boom targets $5,000 fares for a New York to London round-trip, while the same on Concorde cost $20,000 adjusted for inflation: it was its only profitable route. The same fuel burn enables similar fares to subsonic business class among other factors. For long-range routes like San Francisco–Tokyo and Los Angeles–Sydney, 30 lie-flat first-class seats could be proposed alongside 15 business-class seats.

In March 2016, Richard Branson confirmed that Virgin Group holds options for 10 aircraft and Virgin Galactic's subsidiary the Spaceship Company will aid in manufacturing and testing the jet. An unnamed European carrier also holds options for 15 aircraft; the two deals total 5 billion dollars. At the 2017 Paris Air Show, 51 commitments were added for a backlog of 76 with significant deposits. In December 2017, Japan Airlines was confirmed to have pre-ordered up to 20 jets among the commitments to 76 from five airlines. Boom CEO Blake Scholl thinks 2,000 supersonic jets will connect 500 cities and promises £2,000 for London to New York one-way, comparable with existing subsonic business class.

Development

In March 2016, the company had concept drawings and wooden mockups of the aircraft. In October 2016, the design was stretched to 155 ft (47 m) to seat up to 50 passengers with ten extra seats, its wingspan marginally increased, and a third engine was added to enable ETOPS with up to a 180 minutes diversion time. The plane could seat 55 passengers in a higher-density configuration. In 2017, its introduction was scheduled for 2023. By July 2018, it was delayed for 2025. At the time, it has undergone over 1,000 simulated wind tunnel tests.

While other supersonic transport projects have traded cruise speed for lower noise, Boom wants to maintain a Mach 2.2 cruise to fit with transoceanic airline timetables and allow higher utilization, while keeping airport noise to Stage 4, similar to subsonic long range aircraft. Configuration should be locked in late 2019 to early 2020 for a launch with engine selection, supply chain, production site. Development and certification of the airliner and its engine should cost $6 billion, needing Series C investors. Enough money was raised in the B round to hit key milestones: flying the demonstrator to prove the technology; growing the orderbook to prove the market; taking key suppliers for engines, aerostructures and avionics; and lay out the certification process, with many special conditions but with precedents.

At the June 2019 Paris Air Show, Brett Scholl announced the introduction was delayed from 2023 to the 2025–2027 timeframe, following a two-year test campaign with six aircraft.

Design

Its wing configuration is a conventional compound delta for low supersonic drag, it is designed to be like a 75% scale model of Concorde: no low sonic boom unlike the SAI Quiet Supersonic Transport (QSST), or laminar supersonic flow technology from the Aerion AS2. Due to the low 1.5 wing aspect ratio, low speed drag is high and the aircraft requires high thrust at take-off. Boom also needs to address the nose up attitude on landing. Airframe maintenance costs should be similar to other carbon fiber airliners. It should operate at a quarter of the costs of Concorde by relying on dry engines, composite structures and existing technology. The 55-seat airliner would weigh 77,100 kg (170,000 lb). It should be 170 ft (52 m) long by 60 ft (18 m) wide and could accommodate 45 passengers including 10 in first class or 55 with a 75 in (190 cm) seat pitch.

The FAA and the ICAO are working on a sonic boom standard to allow supersonic flights overland. NASA plans a Low Boom Flight Demonstrator in 2021 to assess public acceptability of a 75 PNLdB boom, lower than Concorde's 105 PNLdB. It should not be louder at takeoff than current airliners like the Boeing 777-300ER. Supersonic jets could be exempted from the FAA takeoff noise regulations, reducing their fuel consumption by 20–30% using narrower engines optimised for acceleration over limiting noise. In 2017, Honeywell and NASA tested predictive software and cockpit displays showing the sonic booms en route, to minimize its disruption overland.

Engines

Boom wants to use moderate bypass turbofans without afterburners, unlike Concorde's Rolls-Royce/Snecma Olympus. The only available are jet fighter engines, which have neither the fuel economy nor the reliability required for commercial aviation. As of November 2016, no engine manufacturer can develop such an engine based on sales of only 10 options. Boom needs to address the noise of the high jet speed engine and the tripled fuel consumption per unit distance and per seat of a modern wide-body aircraft. The ICCT also estimated it would burn at least three times as much fuel as a subsonic business-class passenger.

Engines won't be an exotic new design but a modified version of current turbofans, although they will have higher maintenance costs. They should be selected in 2018: a derivative of a commercial engine or a clean-sheet design, unlikely a military engine due to export controls. The 55-seat airliner will be powered by three 15,000–20,000 lbf (67–89 kN) engines without afterburners, with shorter maintenance intervals than subsonic jets. A development of an existing commercial engine core with a new low-pressure spool is preferred over a clean-sheet design. Larger-diameter fans have higher cruise thrust requirements for a higher fuel-burn and lower range but are preferred for higher bypass and lower takeoff noise.

Intake compression would need a low pressure core, and derivatives of existing 3–4:1 bypass-ratio turbofans are a compromise between takeoff noise and wave drag with a good fuel efficiency. For Lockheed Martin Skunk Works' Dave Richardson, suitable engines with low overall pressure ratio are scarce. Development of 1950s–1960s engines like the GE J79, GE YJ93, GE4, PW J58 or Rolls Olympus ended when more efficiencies were pursued and subsequent advances in materials for much hotter cores are not optimized for long supersonic endurance. The PW JT8D or GE J79 are better suited than current engines and staggering development costs render new low-bypass-ratio turbofans unlikely.

Specifications

Data from Aviation International News

General characteristics

• Capacity: 45 passengers including 10 in first class or 55 with a 75 in (190 cm) seat pitch.
• Length: 170 ft (52 m)
• Wingspan: 60 ft (18 m)
• Max takeoff weight: 170,000 lb (77,111 kg)
• Powerplant: 3 × medium-bypass turbofans without afterburners, 15,000–20,000 lbf (67–89 kN) thrust each

Performance

• Maximum speed: Mach 2.2
• Range: 4,500 nmi (5,200 mi, 8,300 km)
• Balanced Field Length: 10,000 ft (3,048 m)

See also

• Supersonic transport
• Supersonic business jet

Related development

• Boom XB-1 Baby Boom

Related lists

• List of airliners