Update – Embraer EMB-145

To simplify and speed up the design and development process, Embraer designers decided to base the new EMB-145 fanjet largely on the already successful Brasilia turboprop regional airliner. This design philosophy has been adhered to so successfully that the EMB-145 will actually incorporate a 75% component commonality with the already proven Brasilia design, so the aircraft structure utilises technology with which the company has already had much experience. It is anticipated that development of the EMB-145 will be speeded up as a result of the remarkably high degree of component commonality while basic development costs should also be kept to the minimum, or about $US300m. First flight is not expected till the end of 1991 and first delivery of a production aircraft to US regional airline, Comairshould be made during late 1993.

By virtue of the fact that the new aircraft is based so closely on the Brasilia design, the EMB-145’s fuselage resembles little more than a stretched version of its predecessor. Design of the new fuselage has literally only necessitated the insertion of just two plugs (one foreward and one aft of the wing) to increase total fuselage length to 25. 8m-total overall length is 27. 08m-and, of the two plugs, only the rear plug and its emergency exit are new Embraer products. The plug located forward of the wing is the same as the already existing section immediately aft of the Brasilia’s wing, so it is in effect already in production. Some modifications to the airframe have been made so it will be better suited to its intended role as a regional jet airliner, but overall fuselage diameter remains constant with that of the Brasilia at 2. 28m. Modifications to the fuselage structure include local reinforcements needed to compensate for the increased weights for operation to 40,000ft (12,200m) with a cabin altitude of 8,000ft (2,440m).

Cabin layout is, as would be expected, very similar to that of a stretched Brasilia, though several minor yet significant modifications have been made to not only improve passenger comfort but also cabin utilisation. Typical configuration of the EMB-145 is 45-50 seats; a double row of 30 seats is located on the starboard side with 15 single seats on the port side. In the 50 seat high density configuration, an additional row of four seats is located at the rear of the aircraft with the toilet relocated to the front of the cabin and the rear baggage compartment made smaller. The cabin aisle has been recessed by 5cm to increase aisle height to a full 1. 82m (6ft). It is 43cm wide at the base of the seating, increasing to 53cm in width at the top of the seats to make walking through the cabin easier. Overhead cabin baggage stowage bins have been increased in depth and their doors widened to accommodate larger items and provide greater total volume, while centre rails have been removed from under double seats to improve accessibility for under seat baggage stowage. An emergency exit door has been added at the rear of the cabin to facilitate rapid evacuation from the aircraft, adding to the existing forward and two above wing emergency exits.

The aircraft will typically be equipped with a galley located in the front of the cabin, very spacious carry on baggage compartments at both the front and rear of the cabin (as well as those above the passenger seats), suit hanging lockers and one toilet (located either at the front or the rear of the cabin, depending on chosen configuration). Thus, as is expected of regional airliners today, passenger comfort is enhanced by having carry on luggage stowed away from the seats to conserve legroom and enable a better standard of inflight service to be provided.

Baggage hold capacity of the EMB-145 compares very well with that of its two competitors, the Saab 2000 and Canadair RJ. The EMB-145’s cabin baggage compartments, underseat stowage space and rear baggage hold can carry some 15cu metres (34. 2cu cm per passenger) of carry on and checked in baggage. According to Embraer, this compares very favourably with the Saab 2000’s 11. 61cu metres (23. 2cu cm per passenger) and the Canadair RJ’s 14. 9cu metres (29. 9cu cm per passenger) of baggage capacity. The EMB-145 will also offer quick change passenger/cargo capability for airlines involved in both passenger and light freight operations.

The cockpit of the EMB-145 is also well equipped and laid out.

The aircraft is to be flown by a two pilot crew with control yokes and columns interconnected, though in the event of one unit experiencing elevator or aileron system jams the connection can be disengaged for flight by just one pilot. The cockpit systems package is available with either the Brasilia’s current avionics package of a mix of analog and digital instruments or with the CBA-123 type all digital instrument panel. With the more advanced avionics package, the cockpit will typically feature an engine indication and crew alerting system (EICAS) with triple redundant display and extensive onboard maintenance capabilities; a four cathode ray tube (CRl) EFIS system, including airspeed indicators in the electronic attitude direction indicators (EADI) and weather radar display in the electronic horizontal situation indicators (EHSI); dual air data computer (ADC) with cross side reversionary capability; dual attitude and heading reference system (AHRS) and cross side reversionary capability; digital high performance CAT IIIA autopilot/flight director system (JAR). Optional equipment includes a flight management system.

All ailerons and elevators are mechanically actuated as are all trims, though the elevator trim is also electrically actuated. The dual tandem configuration rudders are hydraulically operated by two independent actuators and an artificial feel and centring unit is provided as part of the rudder control system. Flap panels and the speed brake/ground spoilers are hydraulically actuated and electrically controlled.

Though the EMB-145 fuselage is quite noticeably that of a stretched Brasilia, it is perhaps the unusual (for a turbofan aircraft at least) above wing mounted engine configuration that is the most noticeable feature of the aircraft’s design. Very similar in position to those of a turboprop, the engines are mounted on two mainplanes each, with vertical/side loads absorbed at the forward mounting plane and vertical/side/torque/thrust loads absorbed at the rear mounting planes.

The mounting of the two Allison GMA3007 turbofans above wing actually offers several not immediately obvious advantages. Above wing mounted turbofans, for instance, offer the same basic weight and force distributions as the original turboprop design, thus minimising the number of necessary wing design changes to be made. Other advantages of the above wing engine mounting are an apparent reduction of foreign object ingestion damage, low inlet flow distortion, a reduction in flyover noise signature with the wings acting as noise shields, improved lift/weight ratio and the lessening of engine damage in the unlikely event of a crash landing.

Despite the fact that the mounting of the engines above the wing has helped to lessen the necessity for wing design changes, the wings have nevertheless experienced quite extensive airframe modifications. The wing profile has been modified for increased area and wing fuel tank capacity, while the lengthened wingspan- 22. 49m as against the Brasilia’s 19. 78m- plus the addition of wingtip winglets offers reduced drag at Mach 0. 75 cruise. Aspect ratio is 9. 3 while wing loading is 370kg per sq metre. The wing redesign thus goes a long way towards improving the original Brasilia design and allowing the EMB-145 to provide economical regional jet operations. Other changes to wing structure have been made necessary by the use of the turbofan engine. The wings have been strengthened to cope with higher cruise speeds and a heat resistant surface covering has been added aft of the engine for protection against the exhaust, which flows directly out over the upper surface of the wing.

The two GMA3007 engines which power the EMB-145 are 6,7501b APR class turbofans. Each is a two spool engine with a 5:1 bypass ratio single stage fan directly driven by a three stage power turbine. The gas generator incorporates a 14 stage variable geometry compressor driven by a two stage turbine, and each engine is controlled by two full authority digital electronic controls (FADEC) without mechanical backup. Currently rated at 6,200lb thrust and approved for operation at 6,640lb, the GMA3007 has been the subject of much attention by Allison to upgrade the engine’s performance. This work has been so successful that Embraer and Allison have been able to boost the predicted speed, range, time to climb and takeoff performances of the aircraft. Though the aircraft has yet to prove itself in flight, predicted figures for the EMB-145’s performance are quite impressive.

The most significant improvement in predicted performance brought about by refinement of the powerplant has been that of maximum cruise speed. Initially predicted to be around 405kts (750km/h) at 36,000ft (10,900m) in standard atmosphere (ISA) conditions, this has been corrected to at least 428kts (787km/h) at 36,000ft ISA at 95% maximum takeoff weight (MTOW). The engine improvements are expected to allow the aircraft to climb to 40,000ft (1,220m) in just 30 minutes at ISA and MTOW, or five minutes·faster than previously predicted. MTOW with a takeoff distance of 4,700ft (1,420m) has been raised to 17,400kg from 16,350kg while maximum landing weight has risen nearly 2,000kg to 18,000kg. Basic operating weight of the aircraft is 10,940kg while maximum fuel load is 4,210kg; maximum payload is 5,160kg. Range for the aircraft with 45 passengers and a MTOW of 18,500kg is 1,125nm (2,084km), though with 50 passengers maximum range decreases to 900nm.

To put these figures into some perspective, an EMB-145 operating out of Sydney with 45 passengers could comfortably reach all major eastern cities and needs just one stop to fly on to either Alice Springs, Darwin or Perth, according to Embraer. Out of Alice Springs, the aircraft can offer services to all mainland centres, except Perth, while from Brisbane the -145 can service the Australian east coast and even fly to Adelaide. If servicing Melbourne/Canberra, the aircraft, with 50 passengers and a MTOW of 18,500kg, could fly its passengers from point to point in about 56 minutes (congestion-induced delays not included), whilst on Newcastle/Brisbane a flight sector time of 1 hour 5 minutes with similar operating weights and flight conditions could be expected. This obviously compares very well with turboprop competitors.

The secondary non stop point to point route of course will be the future province of aircraft in the regional jet class and will open up a plethora of new route opportunities that previously have been undreamt of. Because the EMB-145 is not due to make its first flight until late 1991 it is of course impossible to corroborate flight per formance data though Embraer’s design figures show that the EMB-145’s 428kts maximum cruise speed should be below that of the Canadair RJ (459kts) but, naturally, above that of the Saab 2000 high speed turboprop (360kts). Similarly, fuel performance is between that of its two competitors with, according to Embraer, the RJ using 46. 3Ib/seat hr and the Saab 2000 using 33. 9Ib/seat hr, as against the -145’s 42. 8Ib/seat hr. Landing field length of the Saab 2000, at just 1,350m, is well below that of the two jet aircraft, the RJ’s 1,540m though being marginally shorter than that of the EMB-145 at 1,550m.

From the above figures the Canadair RJ would appear to be a superior aircraft performance wise, but Embraer claims that the projected cost of the EMB-145- around $US12m as against the RJ’s $US14-16m -and marginally cheaper operating costs help make up for this. Saab officials, acknowledging that the 2000 is a slower aircraft, claim the shorter routes to be operated by regional airliners almost negates any speed advantages held by either the EMB-145 or the RJ, especially when airport delays and holding patterns are taken into account. The 2000 is therefore seen as a serious competitor by Saab and to a lesser extent by Embraer, but it is without doubt the Canadair RJ which will provide the most competition for the EMB-145. Both regional jets are aimed squarely at the US regional market and have comparable performance figures to attract potential customers.

Embraer officials believe the recently announced BAe RJ70 can be discounted as a serious threat to their product. The RJ70 – along with the proposed shortened fuselage Fokker 100 and Fokker 60 – is both larger (seating 70 passengers) and features very different operating performances and costs.

The Canadair product at this stage has the advantage of having been flown for more than a decade in its well known corporate jet guise, whereas Embraer’s performance figures will be mere predictions until some time during the 1992 flight test program. It is significant, however, that despite the fact that the RJ does appear to have superior cruise speed performance figures, and has attracted at least 139 orders and options, no major US customer has been announced other than Skywest which has ordered 10. Embraer, on the other hand, has been able to achieve its the first significant US EMB-145 sales to US regional airlines, Comair (options on 30) and Westair (options on 60). These prospective sales are important for they are really the first sign of significant interest from US regional airlines in the still relatively new 50 seat regional jet class of airliners; it is, after all, the US regional market that both the RJ and EMB-145 are primarily aimed at. Embraer sees this market developing to the extent that some 1,000 regional jets will be required over the next 15 years, of which the EMB-145 is expected by Embraer to fill at least 50% of orders. At present Embraer holds 297 EMB-145 options and letters of intent from 19 customers in 12 nations.

From all accounts the Embraer EMB-145 is potentially a ‘winning’ design. It has already achieved the important first sale in the US market, but Embraer must now continue development of this promising aircraft so that its performance figures at least equal, and possibly better, the figures being forecast by the design team. Given Embraer’s proven ability to produce quality, high performance and fast selling aircraft, one should not be too surprised if the EMB-145 does perform as expected (if not better) and subsequently sells very well in the soon to takeoff regional jet market.