First analysis of Mitsubishi Regional Jet, MRJ

Discussion

The MRJ is presented as a third generation regional jet which will enter service with launch operator ANA in 2017 if the program stays on track from now on. It is marketed as a 90 seater with a range just below 1800nm in its most capable variant, the MRJ90LR.  Entering service in quantity in 2018 with the new generation geared turbofans from Pratt & Whitney (PW), it competes with Embraer’s second generation E-Jet, 175 E2, rather than today’s regionals from Embraer, Bombardier or Sukhoi. It is clearly smaller than the CSeries CS100 at 110 seats, therefore we concentrate the comparison on its real competitor, the E-175 E2, which will be available 2020.

Sales

Mitsubishi has 223 firm orders and 184 options, a respectable number at this stage before EIS, but the customer base is a narrow six, including 20+20 from US start-up Eastern Airlines. SkyWest Airlines, the regional carrier that serves mainly Delta Air Lines, has 100 firm orders and 100 options, a customer concentration that is generally undesirable.

Cabins

As can be seen from Figure 1, the cabins between MRJ90 and E-175 E2 are virtually identical yet the fuselage dimensions are very different.

MRJ vs E2 175 side and cabins upd

Figure 2. Fuselage dimensions and cabins for MRJ90 and E-175 E2, 92 seats at 29-30 in pitch. Source: Mitsubishi, Embraer and Leeham Co. Click on image for crisp view.

The fundamental difference between the aircraft is how the designers have placed the luggage compartments. Embraer has placed the luggage in a lower bubble in its double bubble fuselage whereas Mitsubishi has placed the luggage after the cabin, in the rear fuselage. The cabin cross sections are almost identical, with the MRJ having a little narrower foot area and crown which makes a difference for the overhead bins. MRJ bins accepts roller bags on the side whereas E-175 E2 has managed to take them wheels first like CSeries, Figure 2. This means that MRJ will only have half the capacity for roller bags in the overhead bins.

Regional cross sections upd

Figure 2. Cross sections for CRJ, CSeries, EMB, E-Jet and MRJ. Source: Bombardier, Embraer, Mitsubishi and Leeham Co. Click on image for crisp view.

Dimensions

MRJ has a smaller cross section than E-Jet, it circular fuselage represents the top bubble in Ejet’s double bubble fuselage, consequently it stores the luggage behind the cabin, which makes for a long fuselage. Mitsubishi has projected both a shorter version, MRJ70 (-2.4m) and a longer, MRJ100 (+2.5m) of the present MRJ90. Of these, it is doubtful that the shorter will be built as the center of demand is moving up over the years and a shorter version would probably not be available before 2020. It would make more sense for Mitsubishi to put its money on the longer version when the MRJ90 is certified and in production.

Figure 3 shows the planform on the two aircraft and Figure 4 lists the main characteristics.

MRJ vs E2 175 planform upd

Figure 3. Planform with span for MRJ90 and E-175 E2. Source: Mitsubishi, Embraer and Leeham Co. Click on image for crisp view.

The 175 E2 wing has longer span and more efficient raked wingtips, it is further specially built for the E175 with a lower wing area which gives a higher aspect ratio. The low wingloading of MRJ90 (below 500 kg/m2) indicates that the wing was designed to cover the larger MRJ100 as well. This results in a somewhat higher drag as wetted  area increases. Low wingloading gives good takeoff performance but the takeoff performance of E175 is more than adequate at 6,200 feet on a normal day.

Production

The MRJ is a metal fuselage and wing. Originally Mitsubishi intended to have a composite wing, but after design and production challenges on the Boeing 787 program, for which Mitsubishi is the industry partner for the wing and wing boxes, Mitsubishi opted for the less complex metal design. Officials said that the smaller regional jet simply didn’t benefit enough to go with a composite wing, but there was widespread industry speculation that Mitsubishi learned from the 787 experience and went simpler for the MRJ.

It does use composites for the vertical and horizontal tail however and there it is breaking new ground. For the first time “out of autoclave” carbon fiber reinforced plastic, CFRP, is used for large structural parts in a modified resin infusion method called Advanced Vacuum assisted Resin Transfer Moulding, A-VaRTM. Mitsubishi has worked with Toray (Japan) [together with Hexcel (US) the dominant producer of CFRP fiber and production systems] to develop this first aircraft quality “out of autoclave” production system. By using glas fiber addtions to the weave and non epoxy additions to the low cost, low density, resin the curing process can be controlled in the mold so that only vacuum bagging is needed for first cure followed by owen cure to finalize the part.

The design of MRJ is very conventional with no real innovations in the design concept, it might be that its most important contribution to the aeronautical history will be its new CFRP production method. In our interview with Airbus CEO Fabirce Brégier from 2 weeks ago he pointed out that they do not know how to produce large CFRP parts like fuselage panels / barrels in a rate of 80 fuselages per month, a large part due to parts needing autoclave curing.

Main data and first look into efficiency

Figure 4 lists main data for the most capable of the MRJ90 versions, MRJ90LR with a Max TakeOff Weight of 42.8 tonnes. It is the variant which come closest to the range of E175 E2. Both use the PW GTF engine in its smallest variant, the 57 inch PW1700G. Therefore range differences come down to aero efficiency as MRJ, having the lower range, is not fuel limited whereas E175 E2 is. It can also be a result of the low maximum flight level of MRJ, FL 390. The aircraft with its low wingloading will reach this limit on most flights above 1000nm. E175 E2 has FL 410 as upper limit.

MRJ vs E2 175 data upd7

Figure 4. Main data for MRJ90 and E175 E2. Source: Mitsubishi, Embraer and Leeham Co.

The empty weight of the MRJ is given as 25 tonnes, we have put it the same as the target for E175 E2 which we understand is around 26 tonnes. Should MRJ90 come in at its target empty weight it would be the first aircraft program in history that does that, we have therefore put both at 26t to clearer see what the aerodynamic differences means on the typical distances these aircraft fly.

Using our propitiatory performance model we can see that E175 use 3% less fuel on a typical 500nm mission. On the occasional longer sector of 1500nm this increases to 4%. It remains to be seen how these programs finally perform on the weight side, on the short mission these aircraft fly, weight can be more important than aerodynamic performance.

Summary

Mitsubishi has designed an attractive airplane that we think will split the lower end market with Embraer. Bombardier’s aging CRJ series can’t compete on passenger experience. In our view, the CRJ is fast approaching the end of the line. The Sukhoi SSJ100 has a decent order book, but production issues and the overhang of Russian international politics work against this aircraft.

Scott Hamilton contributed to this article.

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