Inside Gulfstream’s special mission modification facility in Savannah, Georgia, two green aircraft are bulking up – from sleek private business jets to action-ready military configurations. With their seasick pallor, the G550s have an almost Frankenstein quality as their iconic oval windows are closed up, noses are flung open and tails are stripped away to prepare for more robust missions.

For 50 years, Gulfstream has been doing this type of conversion of its business jets into special mission aircraft, starting with the delivery of a modified Gulfstream I for the US Navy’s bombardier and navigation training mission. Since then, the company’s special mission portfolio has expanded into executive airlift, medical evacuation, transport, airborne early warning and control, and intelligence, surveillance and reconnaissance (ISR). More than 2,500 Gulfstream jets fly around the world, including 207 built for special missions in 39 countries, counting 70 supporting the US government.

Currently, the US Air Force is grappling with two high-value aircraft recapitalisation contracts, to replace its Northrop Grumman E-8C Joint Surveillance Target Attack Radar System (JSTARS) and Lockheed Martin EC-130H Compass Call fleets. For Gulfstream, capturing both deals could cement its special missions business for the coming decades. But both replacement programmes are fraught with acquisition delays and industry squabbles. On the JSTARS side, the USAF has dragged its feet for years on a replacement aircraft. After battling other services on the need to replace its current Boeing 707-based E-8Cs with a manned jet, rather than an unmanned ISR platform, it finally appeared to have put the programme on track last year.

Israeli G550 AEW

The Israeli air force has operated G550-based special electronic missions aircraft since 2005


For these electronic warfare platforms, Gulfstream has some notable international experience. G550s are used by several air forces as VIP transports, but both Italy and Israel operate conformal airborne early warning variants. Israel, two operates a pair of G550s called “Shavit”, with special electronic missions payloads partly accommodated by the sort of belly canoe which characterises the USAF’s E-8C JSTARS fleet.

The JSTARS recapitalisation is slated to reach initial operational capability by 2024, and the USAF is scheduled to award a contract in fiscal year 2018. In July, Gulfstream revealed that its JSTARS offering would include a refuelling nozzle mounted on the G550’s nose. However, the company has also considered the more conventional refuelling position on the aircraft’s crown, so the nose design is subject to change. The G550 would not be alone in its nose-mounted design; both the USAF’s Fairchild Republic A-10 and Boeing B-1 have similar receptacles. No Gulfstream aircraft has been certified for air-to-air refuelling, but the air force requires the capability for the JSTARS ground surveillance mission. Current Gulfstream aircraft store fuel in the wings, rather than a separate bladder or tank.

Meanwhile, the Compass Call replacement programme has proceeded in fits and starts as a changing USAF acquisition strategy has come under fire. The service is proposing a so-called “cross-deck” plan to transplant mission equipment from legacy EC-130H aircraft into new airframes. It initially wanted to move to a G550-based platform, but last year competitors including Boeing and Bombardier demanded an open competition for the replacement.

So the air force changed strategy earlier this year, abandoning its push for a sole-source award to Gulfstream, and instead named L3 Technologies as the systems integrator for the Compass Call cross-deck effort. However, that plan failed to satisfy Boeing and Bombardier, which argued that a history of partnerships between L3 and Gulfstream would secure the aircraft award for their rival regardless.

As Boeing put it in a 25 May statement: “The air force's approach is inconsistent with Congress's direction in the 2017 National Defense Authorization Act and seems to ignore inherent and obvious conflicts of interest. We believe that the US Air Force and taxpayer would be best served by a fair and open competition, and that the air force can still meet its stated timeline of replacing the ageing fleet of EC-130Hs within 10 years.”

Notably, according to USAF documents both the Boeing 737 and Bombardier Global 6000 miss the requirement marks for Compass Call. The mission requires a total cargo capacity of 9,080kg (20,000lb), including 5,900kg of prime mission equipment. But in the Global 6000's battlefield airborne communications node configuration, its payload capacity is “marginally insufficient”, the service says. It has also noted that Bombardier’s offering does not meet aperture requirements without modification, and would require a supplemental type certification that could incur up to $180 million in additional costs and a three-year schedule delay.

Boeing’s 737 would be forced to burn significant fuel to reach its maximum 41,000ft altitude, trading loiter time for height, and is unable to meet both needs, the USAF says.

During a July media day in Savannah, Gulfstream officials pushed the G550 as the ideal solution for the both the air force’s JSTARS and Compass Call missions, but did not reach into as much detail as during a 2015 JSTARS media blitz. During a tour two years ago, Gulfstream and its prime contractor for the JSTARS competition, Northrop, showed off a modified G550 with a large belly canoe with room for radar sensors. While Gulfstream generally looks to re-use existing canoe designs, it is likely that a new design will be chosen for the JSTARS mission.

Troy Miller, Gulfstream’s vice-president of special mission sales, and Leda Chong, senior vice-president of government programmes and sales, hail the smaller business jet as more nimble – while characterising airliner-based offerings as cumbersome. Miller emphasises the G550’s higher altitude, comparing a traditional airliner certified to fly at 41,000ft with a Gulfstream’s 51,000ft capability, and argues that large engines hanging off an airliner's wing could affect the aircraft’s field of view.

“One of the biggest issues is terrain blockage,” Miller says. “That additional 10,000ft can make a huge difference in identifying enemy forces that are using mountains or rugged terrain to mask their movements. The radars themselves are able to perform at higher altitudes, and because of additional line of sight they can do more collection.”

Both Gulfstream and its competitors have argued that size matters for the JSTARS and Compass Call missions, but while airliner manufacturers are pitching “room for growth” as a selling point for their platforms, Gulfstream argues that those aircraft simply provide excess space. “One of the advantages of being smaller: I can be closer to the area of interest,” Miller says. “There is a significant number of airfields, for which the air force and navy evaluate annually, that business jets can operate from and airliners cannot.”

While business jets may be able to land in tougher spots and on more air bases, business jet manufacturers like Gulfstream must weather a stormier market this year. According to an industry outlook from Flight Ascend Consultancy released ahead of the 2017 European Business Aviation Convention in Geneva, predicted that deliveries would decline by almost 4% this year, and an excess of models would dampen prices. Ascend characterised Gulfstream’s G450, G550 and G650 models as “soft” and “on watch”.

Gulfstream counters that its business jet orders have not dipped, and that a significant backlog still exists.

“It has not dropped off,” the company said in July. “We continue to have a backlog stretching into 2018. We have approximately 245 G650s and G650 ERs [extended range] in service. It continues to be a very strong performer for us.”

The company does not split its backlog for the G650 and the ER variant, since both aircraft roll off the same production line. Demand has remained steady for the G650, although the airframer admits it expects sales to decrease from the 200 firm orders it received after the type's launch. Company officials also have answered with an emphatic “no” when asked whether G650 production would end in 2019. Gulfstream has also pushed back on the assumption that a year-long backlog was small in the grand scheme of orders.

“It’s really not a sneeze away,” says Gulfstream. “Typically it would be nine- to 12-months backlog for the 550, for example. So if you think late 2015 is actually 17 months, it’s almost double the nine-month backlog that we would typically have.”

Whether the declining business jet market means Gulfstream is pursuing the special missions sector more remains unclear, although Chong and Miller would like to see specialised G550 configurations expand. In an interview with FlightGlobal at the Paris air show in June, Miller said that while the magnitude of military aircraft demand was increasing, Gulfstream was focusing on the commercial market.

Back inside the modification facility, the two business jets fresh from the production line are stripped of their engines, avionics and interiors. Flight controls and wing leading edges are taken away, leaving a basic, reduced-weight aircraft ready to be optimised for the special mission role, Miller explains. On one aircraft, the tail is removed and replaced with a cone to make room for sensors in the rear of the aircraft. Gulfstream also makes a significant change to the nose, which now houses heavy sensors.

Part of the modification process seems redundant; bundles of wiring on business jets are removed and replaced when preparing special mission aircraft, because jets coming off the production line are all identical. That process, says Miller, is an advantage for Gulfstream, buying it the freedom to respond to a special requirement with any available aircraft. That freedom, he claims, is not available to competitors offering airliner-based products, which typically undergo some modification on the production line if destined for a special configuration.

One of the more perplexing reconfigurations is the removal of Gulfstream’s patented oval windows. On almost all special mission aircraft, the heavy windows are removed to either reduce weight or use the space for a different capability. Often, the space is outfitted with purpose-made plugs with connectors on both sides which attach to sensors outside the windows, Miller says.

Gulfstream continues manufacturing the jets with the windows, rather than omit them initially, since they are required for certification. The company could obtain a waiver, but Miller says designing aircraft without windows would reduce its flexibility. “It’s not a significant cost or time consideration to be able to do that [modification],” he says.

All the modifications are mounted externally to the green aircraft structure, which is engineered to include mounting points and contact points for sensors. Gulfstream not only designs the outer mould line of the aircraft, but works with its customers to understand where those sensors and equipment are to be placed.

“I would imagine that doing this as a third-party is even more challenging,” Miller says. “So we think it’s really important to have the same processes, people, facilities and certification flight test going on.”


Ground crew prepare an EC-130H Compass Call at Bagram air base, Afghanistan. Its mission equipment will be moved to another platform

US Air Force

Still, the actual installation and flight test of mission equipment would remain the responsibility of the prime contractor, he adds. In some cases, Gulfstream will install and fly an inert dummy resembling the shape and weight of the mission equipment, since some of the sensor work is classified and completed at the prime’s facility. But, Gulfstream remains engaged through the delivery of the aircraft and may even provide product support for the lifespan of the aircraft, he says.

“It’s not as if we do the group A modifications, hand the keys over to the prime and say goodbye,” he says. “It’s a relationship we have with the primes and the end users for the entire lifespan of the aircraft.”

Although the USAF has emphasised that there is no connection between the JSTARS and Compass Call competitions, Gulfstream is developing a 10-year plan that could include capturing both those contracts. The company is examining where it could expand facilities and realise synergies across programmes, such as by sharing tools.

“We have strategic planning sessions all the time about how do we best utilise all of these assets,” Chong says. “Whether it takes the form of human resources, facilities, materials, all of that. So it’s not one or the other thing. I call it an orchestration.”