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GROB SPn (2005 FIRST FLIGHT UPDATE)

September 2005

Category: Business Aircraft - Development & Certification

Author: Mike Vines

Response growing strong to SPn after maiden flight.

GROB Aerospace’s ‘seeing is believing’ philosophy of building new airplane designs, rather than talking them up, is definitely paying off according to Charles Porteous. He is the man in charge of marketing the all-composite GROB SPn Utility Jet. Zurich-based Porteous is employed by ExecuJet Aviation Group, which is jointly working with GROB as the exclusive worldwide sales distributor and maintenance support partner for the SPn.

"We are pleased with the customer interest in the SPn but can’t disclose the order book," said Porteous. "But since the launch at Paris and the first flight, the response for the aircraft has been very strong."

Before its Paris launch on June 14th very few people even knew of GROB’s desire to enter the business jet market. Rumors were rife that the company would announce a new aircraft program of some type at Paris, but imagine the surprise when GROB introduced its flight ready prototype and presented it at Le Bourget. We covered the story of the airplane’s introduction to the public in last month’s issue, but since then the newly registered aircraft (D-ISPN) achieved a successful 66-minute maiden flight in Germany on July 20th. The flight was an exercise in which aircraft system functionality tests and general handling characteristics were checked out.

"The prototype performed very well in terms of take-off performance and met its specification," Porteous told World Aircraft Sales. "We are very pleased with the way the program is progressing – we’re on schedule."

On its maiden flight the aircraft was commanded by Capt. Gerard Guillaumaud and co-testpilot Tore Reimers. According to Guillaumaud, "all systems and controls performed as expected, the aircraft was easy to handle and a pleasure to fly". A second flight test aircraft is due to join the program in March 2006 to speed the expected 1,000 hours flight test time required for certification.

The first flight was made from GROB’s neighboring ex-military airfield, now Allgäu Airport (EDJA), near Memmingen, southern Germany. According to a GROB spokesperson, once the aircraft’s short take-off and landing characteristics are confirmed further flight-testing will then continue at GROB’s factory airfield at Tussenhausen Mattsies. The aircraft’s flight test program is to reach full expansion of the flight envelope by the fourth quarter this year.

The first flight followed an intensive period of aircraft systems ground test activity. A static test airframe has, ‘successfully passed a program of full strength testing on the fuselage and wing’ says GROB. A third SPn airframe is currently being built and will become the program’s ground fatigue test vehicle.

"We’ve tried to combine the operational flexibility of the turboprop with the performance and comfort of a jet," explained Porteous. "We saw a significant market opportunity for an aircraft that has this performance capability. The design of the fuselage incorporating the large entrance door (53.9 inches high by 33.1 inches wide) is one of those specific design features which gives us real utility capability."

Rugged Aspirations

GROB’s ambition, with its clean sheet design, is to produce a rugged utility/passenger jet aircraft with a Balanced Field Length of 3,000 feet and capable of operating from ‘unimproved’ runways to deliberately challenge some of the industry’s twin turboprops.

To allow operations from un-improved runways, the SPn’s flaps will have replaceable armor plating on their under-surfaces and the aircraft’s belly clearance is set high to avoid debris damages and ingestion. The main landing gear legs are of the long travel, trailing link design, to accommodate rugged field performance.

The aircraft’s super light-jet sized cabin boasts a volume of 405 cubic feet, with headroom of 5 feet, 5 inches (thanks to a 3-inch dropped aisle running most of the length of the cabin), and a standard eight-seat double club configuration. The modular interior is aimed at quick conversion to dedicated cargo missions, a 50/50 cargo split, or for use as an air ambulance.

It is designed for a service ceiling of 41,000 feet, but even operating at FL 330 the cruise speed is estimated to be in the region of 407 KTAS. Pressurization will be 8.4 psi, giving a maximum altitude of 8,000 feet in the cabin. If all goes well GROB says the aircraft will be ‘the largest private jet certified for single-pilot operation’. The company expects that work towards certification will accelerate towards the first quarter 2007, with EASA approval followed by FAA qualification and customer deliveries in the second quarter. The current SPn cost, ‘equipped for operation,’ will be around €5.8 million euros ($7 million).

When fully equipped, SPns will be equipped with Honeywell’s APEX integrated glass cockpit to ease pilot workload and the popular FADEC controlled Williams International FJ-44-3A turbofans rated at 2,800 lbs thrust.

The mean-burn engines and the aircraft’s carbon fiber construction are expected to give the SPn an estimated range of 1,800 nautical miles with one pilot and six passengers (or equivalent freight) aboard, given standard NBAA reserves in ISA zero wind conditions.

This means that the aircraft could fly legs from Dallas-Bermuda, Dallas–Calgary or to Halifax-Nova Scotia from this central US oil town. In Europe the range figures link city pairs such as Munich–Reykjavik, Munich–Luxor, Egypt/Munich-Perm in Russia.

Indeed, even with eight passengers aboard and one pilot, GROB claims a range of 1,670 nm. This airplane would seem to be one to watch in the coming months.

á More information from www.grobspn.com

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