Developers of the Supersonic Business Jet Need Both
Technological & Market Progress
It's been 12 months since the supersonic business jet (SSBJ)
avalanche hit the 2004 NBAA convention. In Las Vegas that year two new
contenders — Aerion and SAI — lined up to join existing players like Gulfstream
in the notional race to build the first SSBJ. Aerion and SAI brought with them
high hopes and big name backers, with funding coming from billionaire Robert
Bass and the foundation established by the late Gulfstream founder Allen
Paulson, respectively.
Gulfstream already had its own irons in the fire, working on
several radical technology solutions to deliver the quiet flight
characteristics that it believes are the only way to make supersonic flight
over land practical. During the Paris Air Show in June the field became wider
still with an announcement by French and Japanese industrial groups that they
intended to team up to develop a supersonic transport also. Dassault has always
been one of the leading potential SSBJ builders and interest in this class of
radical new aircraft has never been higher.
However, the widespread enthusiasm unleashed at NBAA 2004
has been tempered by the cold realities that face all the SSBJ teams. The
difficulty remains the same — how to solve the towering equation of aircraft
cost plus aircraft noise, and make that equal sufficient customer demand to pay
the bills. Big bills.
Yet, despite the time and the effort and the cost that it
will take to bring an SSBJ to the market. Pretty much everyone in the business
is convinced that supersonic business jets will emerge — and that they are the
right way to go. One industry expert, with years of experience in the SSBJ
design field, told Show News, "Commercial supersonics has to start again with
the business jet market. It's right there where aviation started — small
aircraft for rich people. It can only work, at least to begin with, if you have
customers who don't care about the price. Right now we are not seeing any
strong interest from the military, so the civil market is going to have to
support this all alone. With Concorde we started too big, at the wrong end of
the market. This time we have to prove that it works — then move up the scale."
The three big names setting out their supersonic stalls at
NBAA are:
Aerion
This twin JT8D-219-powered SSBJ could be in service by 2011,
says the Reno-based Aerion team. The company's latest market research, released
in June, predicts sales of between 220 and 260 aircraft over the next 10 years.
For a 20-year program lifespan Aerion says it could build 500 of the $80
million jets. Crucially, Aerion's 'low boom' design does not require any change
to the existing rules that ban overland supersonic flight. The aircraft is
conceived to cruise at a maximum of Mach 1.6 while over water and then
decelerate to Mach 0.98 over land.
The basic aircraft weighs in at 90,000 lb MTOW and should
deliver a range in excess of 4,000 nmi.
The design is based around an unswept natural laminar-flow wing without
using any kind of airframe shaping to mitigate the sonic boom signature.
However, plans (and patents) exist for a follow-on aircraft that would use
airframe shaping. Aerion is now moving out of its initial SSBJ wind tunnel
testing phase and continuing the search for risk sharing partners.
Supersonic Aerospace International (SAI)
SAI is benefiting from its relationship with the Lockheed
Martin Skunk Works, where a two-year aircraft and system design co-operative
effort got underway earlier this year. Dubbed the QSST (Quiet Small Supersonic
Transport), SAI is planning a 12-passenger Mach 1.8-capable aircraft with a
4,000 nmi range. Initially it planned to build a 60% concept demonstration
aircraft but says it will no longer require this. SAI is now in Phase 2 of its
program, refining the design and making detailed decisions for the QSST, such
as its engine choice. The company says it is considering powerplant options
from General Electric, Pratt & Whitney and Rolls-Royce. Like the Aerion
aircraft, SAI's QSST is priced at around $80 million and a first flight is
anticipated in 2011. The QSST
differs from its other rivals by being a very large aircraft, at least in
business jet terms. With a wingspan of over 65 ft and some 130 ft in length,
the QSST weighs in at around 153,000 lb. This makes it a very big aircraft
indeed and SAI is already studying a potential stretched version that could
carry up to 40 passengers.
Gulfstream
Of the three American SSBJ competitors Gulfstream Aerospace
has been in the race the longest but has said the least about its intentions,
and its design.
The company is known to be working on a radical aircraft
configuration — the Quiet Supersonic Jet (QSJ) — that will deliver ultra-quiet
supersonic flight over land, with almost no noise signature. Gulfstream has
reduced its aircraft's signature at ground level to just 55 dB — literally whisper
level. All of Gulfstream's considerable developmental efforts have been poured
into noise reduction — transforming the classic N-shaped pressure wave of a
conventional sonic boom into a smooth, sinusoidal curve with none of the
pressure pulses that produce the twin bangs that accompany conventional
supersonic aircraft.
Gulfstream has optimized its aircraft to cruise at around
Mach 1.8, at between 51,000 and 57,000 ft. All Gulfstream will say about its
QSJ is that the aircraft will look "distinctly different" — the shape of the
integrated vehicle is absolutely key to delivering its performance and sound
levels. Gulfstream has not announced any engine selection, but the company is
thought to favor a straightforward turbofan, without too much diversion into
issues of bypass ratio or variable cycles. It is in discussions with all three
of the major engine manufacturers.
Added to this list is Dassault, leader of the pan-European
High-Speed Aircraft (HISAC) study group. This teaming of 37 partners is studying
several potential aircraft configurations — all of which are large transport
aircraft. This work could translate into the SSBJ realm, although Dassault says
that it has no intention to start work on such an aircraft before the end of
the decade.
Back in the U.S., major players in the SSBJ sectors joined
forces in 2004 to establish the Supersonic Cruise Industry Alliance. The group
comprises Boeing, Cessna, Gulfstream, Lockheed Martin, Northrop Grumman and
Raytheon, plus General Electric, Pratt & Whitney and Rolls-Royce's Allison
Advanced Development unit. The 10th member is fractional ownership operator
NetJets. The Supersonic Alliance is now working with the FAA and NASA to try
and launch a government-backed supersonic flight demonstration program that
would work out the technological and regulatory issues that still need to be
overcome. It remains to be seen if NASA's besieged budget can support the $1
billion that this initiative is expected to cost. Neither has it gone
unremarked that the U.S. aviation industry is now looking for public money to
help build an elite product for the super rich.
Perhaps the biggest hurdle for any attempt at building a
successful SSBJ is overcoming the regulatory bans that exist on overland
supersonic flight. Gulfstream has been the most vocal in its belief that any
meaningful SSBJ concept must be able to fly at maximum speed over populated
areas. Its analysis of typical Gulfstream IV sector lengths — that equate to
the proposed SSBJ ranges — show that only 25% of flights are over water, so an
overland solution is essential.
Any change to today's restrictions will require a worldwide
international agreement to ICAO standards. These standards, covering aspects
such as aircraft noise and emissions, are set out by ICAO's Committee on
Aviation Environmental Protection (CAEP). However, the CAEP meets only every
three years, so if SSBJ developers are able to submit some hard figures to the
CAEP by 2010 that would produce a world standard by 2013 that could only be
adopted by 2015, at best.
There is still some distance to run in the SSBJ race. —Robert Hewson
