32 AEROSPACEMANUFACTURING | jANUARy 2010
Metallics i Machining
“Our composite issues were a size/weight trade-off, and
have no bearing on larger aircraft,” Takigawa confirms. “The
MRJ will feature composites in its empennage. However, the
technology being used for the empennage is different to what
was tried for the wings, because the needs are quite different.
Empennage sections are under less stress than the wings.”
The company cites two other main reasons for switching to
aluminium: manufacturing flexibility and manufacturing speed.
Since announcing the launch of the new aircraft in March
2008, Mitsubishi has so far confirmed two aircraft in the
fleet: the MRJ-70, seating 78 people; and the MRJ-90, for 92
passengers. Following customer feedback, it has also drawn up
plans for a ‘stretch’ version – the MRJ-100 – but it has yet to
confirm that it will build this aircraft.
According to Takigawa, aluminium will allow the company
to design a different wing for each model in its fleet. With
composites, it would have needed to use the same wing in each
The MRJ’s first foreign customer: Trans States Holdings’ president, Richard Leach
with Mitsubishi Aircraft president, Hideo Egawa
case.
“Aluminium allows us to build the optimum wing for each
model,” he adds. “It is easier to scale up and down, and can be review. Following customer feedback, Mitsubishi made some
done so more quickly. With composites, we would have to use other alterations. Two separate cargo compartments will
the same wing structure for the MRJ-70 and the MRJ-90.” be combined into a single compartment, but taking up the
The composite wing design would have been optimised for same overall volume (644ft
3
). At the same time, the plane’s
the MRJ-90, which would have meant weight penalties for the dimensions have been increased slightly: a 2.5 inch increase in
MRJ-70. It is likely that composite wings would have needed fuselage height creates an extra 1.5

inches of headroom. The
reinforcement – adding further weight. volume of overhead bins has been increased by 12%, which will
“With an aluminium wing, one way to further reduce weight allow more carry-on baggage. A critical design review will take
is to scrape the surface,” he says. “You can’t do that with a place this summer.
composite wing.” And the company has already signed up two customers.
In addition, using aluminium should help Mitsubishi make Japan’s All Nippon Airlines (ANA) was first to pitch in, with
up for lost time: the MRJ-90 (which is ahead of the MRJ-70 an order for 25 planes (15 firm, 10 options). This coincided with
by about a year) was originally scheduled for completion in late the official launch of the aeroplane back in March 2008. More
2013. This has fallen back to early 2014 – with a first flight due recently, in October 2009, US regional carrier Trans States
in mid-2012. These dates would have been delayed even further Holdings (TSH) ordered 50 planes – with an option on 50
had the wings been made more.
from composites. TSH president Richard Leach said: “The MRJ is a game
“By switching to aluminium, changing regional jet that takes into account the environment,
we can eliminate many of as well as passenger and airline needs. It will reduce fuel
the composite tests – such consumption, noise and NOx emissions – this means savings on
as stress testing – which can operating costs. By combining the largest cabin in the regional
delay production,” claims jet market with innovative seat design and a very quiet cabin,
Takigawa. we can offer the best comfort of any regional jet.”
The wings were not the Neither TSH nor ANA has specified what proportion of
only change to be made at MRJ-90 and MRJ-70 models they will take. At the same time,
the September 2009 design neither is likely to have any interest in the MRJ-100 – should it
be built. According to Takigawa, that plane is aimed squarely at
Europe.
“In the US, small regional airlines can’t operate larger aircraft.
“Projected weight savings were not
That’s not the case in Europe. Announcing a launch date for
there for such a small aeroplane.”
the MRJ-100 will depend on the reactions of customers in
Europe – that’s the only market looking for 100-seat aircraft.” ❙
Yosuke Takigawa, Mitsubishi www.mrj-japan.com
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40