By Bjorn Fehrm
December 20, 2017, ©. Leeham Co: The Super Sonic Transport (SST) has a new spring. Aerion announced its new partner Lockheed Martin Friday and Boom got a new investor in Japan Airlines (JAL) the week before.
The design of a supersonic transport aircraft is exciting and difficult. Yet it isn’t the key challenge. The engine is.
June 30, 2017, ©. Leeham Co: One of the areas I explored while at Paris Air Show last week was electric aircraft technology. With electric aircraft, we mean an aircraft where the propeller/fan is driven my an electrical motor.
We don’t talk about “more electrical aircraft systems” like for the Boeing 787.
One of the companies investing in technology for electric aircraft is Siemens. A Siemens-engined aerobatic aircraft, the Extra 330LE, made daily flight displays during the show.
June 21, 2017, © Leeham Co.: “It’s all about continuing the development strategy since thirty years” said Mike Delaney, VP of program development for Boeing. “It’s about continuing the development strategy for 30 years producing super efficient twins that support point-to-point networks.”
Delaney made the remarks at the Paris Air Show about developing the 737 MAX 10 and the NMA (New Medium size Airplane).
Figure 1 shows the Boeing products over the years, with the 737 MAX 10 and the NMA filling the gap between 180 and 270 two class seats (note the 748i is no longer part of the chart). The MAX 10 is in place and a tentative NMA is showing the way into the next decade. Read more
By Bjorn Fehrm
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June 15, 2017, ©. Leeham Co: We continued the comparison of Irkut’s MC-21 and COMAC’s C919 last week with an analysis of the cabins and systems. The week before, we compared project time plans, structures and aerodynamics.
Now we finish with an analysis of the economics of the aircraft.
By Bjorn Fehrm
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April 27, 2017, © Leeham Co.: We have in several articles gone through the sizing of an NMA (New Midrange Aircraft). We looked at the fuselage, cabin, wings and engines. Now we will sum the exercises and look at the performance of the resulting aircraft.
Boeing is seriously considering launching an NMA. The key to the launch decision will be the airplane’s economics: for development and production as well as operation.
The idea is the NMA shall have “twin aisle comfort with single aisle economics.” We will now use or performance model to analyze if the final aircraft has these characteristics.
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By Bjorn Fehrm
April 6, 2017, © Leeham Co.: After sizing the cabin of the NMA, the time has now come to size the fuselage. Can a fuselage be designed that gives an NMA “dual aisle comfort with single aisle economics”?
We will investigate the dimensions, the drag and the weight of an NMA fuselage. It will be based on the cabin and design techniques we described in Part 2. We then compare the efficiency of the result with the fuselages of the Airbus A321LR and Boeing 767. This will show if the necessary efficiency can be achieved.
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By Bjorn Fehrm
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April 3, 2017, © Leeham Co.: In the first part of our investigation on how good an NMA can be, we explored low weight and drag fuselage design. We will now continue with the design consequences for the fuselage construction and the cabin.
What drives whether one goes for an Aluminum or CFRP (Carbon Fiber Reinforced Polymer) fuselage?
What will be the typical dimensions for an NMA fuselage and what will be passenger capacities?
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By Bjorn Fehrm
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Introduction
December 15, 2016, ©. Leeham Co: In our article series around the engine for a Boom SST, we established the thrust requirements for the engines in Part 3.
To fulfill these requirements, we have now designed four different engines. Three are of the type that Boom says it is considering, an engine that is based on an existing core.
We based these around a military core with the right characteristics for a low-to-medium bypass SST engine. The fourth engine is a custom-designed straight turbojet, very similar to the engine that propelled the only operational SST, the Concorde.
We will use the reference turbojet to understand the difference to a turbofan in this application and why the selection of an engine for a SST follows different rules than for a normal airliner.
Summary:
By Bjorn Fehrm
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Introduction
December 08, 2016, ©. Leeham Co: Boom Technology and Virgin Atlantic plan to offer supersonic business class passenger traffic over the Atlantic. We covered the type of challenges that this poses in previous articles. The most difficult challenge is finding a suitable engine.
We described what type of engine will be required in Part 2 of the series. We will now investigate what thrust this engine must deliver at different parts of the flight envelope.
How “draggy” is supersonic flight? Why did Concorde and the Tu-144 need afterburners for the acceleration to cruise speed?
Summary:
By Bjorn Fehrm
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Introduction
December 01, 2016, ©. Leeham Co: Boom Technology and Virgin Atlantic plan to offer supersonic business class passenger traffic over the Atlantic. We covered the number of challenges that this poses in recent articles. The most difficult challenge is finding a suitable engine.
We started the investigation into a suitable engine in the last article. A Supersonic Transport Aircraft (SST) needs an engine which is very different from the latest crop of high-performance airliner engines.
The air entering the engine intake at Mach 2.2 is taken from standing still to a speed of 450m/s within a fraction of a meter. This raises the air pressure and temperature more than the combined intake/fan/low compressor does for a modern turbofan. The result is that the core’s high pressure compressor must adapt; it can’t have a high compression ratio (then things get too hot).
Add to that, that the engine must be slender. It can’t have a wide fan and therefore high by-pass ratio because the supersonic drag of such large engines would be too high.
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