Technology reshaping Aviation Partners’ winglets by Ian Goold Pushing the technology envelope as far as physics will allow, Aviation Partners’ winglets research has succeeded in minimizing drag and improving performance. The firm has introduced winglets for the Raytheon Hawker 800 series (below) and Boeing Business Jet (left), and is said to be on the verge of bringing the technology to other models as well. New wingtip technology that Dr. Louis Gratzer, who claimed it “will raise eyebrows” is being de- eliminates concentrated wingtip veloped by Aviation Partners and vortices, which account for nearly may be revealed at the EBACE half of the induced drag gener- show this week. Declining to re- ated during cruise. veal details ahead of time, chief “Vorticity is gradually shed executive Joe Clark told EBACE from the trailing edge,” according Convention News a few weeks to Gratzer. His patented Spiroid- ago that satisfactory completion Tipped-Wing introduces a substan- of flight testing could permit him tial change in winglet design, to announce the novel wingtip de- which aims to control (or at least vices here in Geneva. The U.S. positively influence) the wake vor- company also might identify two tex flowing from a wingtip. more business aircraft platforms The spiroid looks like an ex- for its established Blended Wing- tended wingtip that has been bent wing generates a high cross- while matching the loading and signer’s role being to select the lets which already are available to upward through 360 degrees (as stream velocity and lift-induced maintaining buffet margins. appropriate combination.” equip the Raytheon Hawker 800 if rolled inboard about a longitu- drag wastes energy. Since wing- The challenge for Aviation The spiroid-equipped GII’s series and the Boeing Business dinal axis) to form a large rigid lets reduce vortex strength, they Partners has been to avoid going wake vortex was less intense than Jet (BBJ) and Boeing 737-700 loop. In 2001, Aviation Partners also lower drag. Being a closed too far, since the resulting flexible that of a standard GII, a factor and -800 jetliners. tested spiroid winglets on a Gulf- loop, the spiroid winglet was structure could distort excessively that could allow shorter aircraft- The latest proposed modifica- stream II. The Seattle-based firm seen as the logical outgrowth of under load–thereby causing per- separation distances in airport tion has been derived from previ- said the modification reduced such technology. formance loss or aerodynamic traffic patterns. The company ous work on a “double-winglet, cruise fuel consumption by more According to Aviation Part- problems. Appropriate selection says the spiroid development closed-loop design,” said Clark. than 10 percent. At the time, it es- ners, to achieve minimum in- of an airfoil and location of the greatly expands the performance- Dubbed “spiroid winglets,” the timated that certification probably duced drag, which requires spiroid elements can circumvent enhancing potential of winglets technology was developed by for- would take several years and sug- optimum aerodynamic surface the adverse high-speed effects as- on fixed-wing aircraft. As well as mer Boeing aerodynamics chief gested it could appear on trans- loading, appropriately matched sociated with shock waves and improved performance, the new port aircraft by mid-decade. airfoils are essential for the flow separation. technology could provide opera- Gratzer’s aim was to minimize twisted and cambered spiroid sur- Spiroids must be appropriately tional benefits, such as increased Aviation Partners says that its drag and improve performance at face. And to minimize friction sized for the intended platform safety and less noise. “spiroid” winglets improved the fuel performance of a Gulfstream II all speeds. The vortex developed drag, the winglet’s chord distribu- application, since additional by more than 10 percent. in the wake of a conventional tion must be held to lower limits, weight and skin-friction drag–the ACJ Winglets in the Cards price paid for lower induced Any announcement here at drag–are related to geometry, EBACE 2006 of plans to certify structural load and design ap- current Aviation Partners winglet proach. Accordingly, there is an technology on additional busi- optimum spiroid geometry that ness aircraft–the company is eye- will minimize drag without ex- ing at least two types–could ceeding the structural capability include corporate variants of the of a given wing. single-aisle A320 series. Clark Aviation Partners says that nor- confirmed that Aviation Partners mally this would reduce overall has been approached by Airbus span, another apparent benefit. operators. “We would very much But if a wing has unused struc- like to fly [our winglets] on the tural capability, ultimate drag ben- Airbus,” said Clark, who claims efits can be even greater–albeit to have as many as 25 types on with an increased span. According his “certification wish list” for to the company, “There are many future application. ways to exploit the tradeoff be- Another aircraft family in tween drag, span, structural mar- Clark’s sights has been the gins and wing weight, the de- Continued on page 44 42aaEBACE Convention News • May 3, 2006 • www.ainonline.com Continued from page 42 French manufacturer has tested At different times, the com- for the Raytheon Hawker 800 that tion Partners warns that lead Cessna Citation series. Although such equipment. pany reportedly has considered Clark expects production to be times might increase. “We sug- the bizjet builder has apparently Blended winglets have been winglets for the Boeing 737-300, raised by 50 percent next year. gest that Hawker operators get in ruled out modification of the Ci- installed on four corporate Boeing -400 and -500; 747-200 and With recent sales running at “one line now, because it’s becoming tation X, Aviation Partners is 757s (as well as those of Conti- -400; 767-300ER and 777- a week,” he said 50 shipsets will harder and harder to provide in- known to have considered the nental Airlines). In February, Avi- 200ER, and the McDonnell Dou- be manufactured this year and 75 ventory and [preferred] installa- smaller “straight-wing” mem- ation Partners said that–through glas MD-80. At one stage Boeing next year. Almost 40 sets of tion slots,” said sales vice bers of the Citation family. Clark its joint venture with Boeing–it investigated whether the 717 Hawker 800 winglets had been president Gary Dunn. The com- also has cited the Dassault Fal- was close to seeing 1,000 blended could be so equipped. installed by early April, with pany says its winglets reduce con’s low-aspect-ratio wing as a winglet-equipped private and So successful has been Avia- backlog put at “about 20.” Hawker 800 fuel burn by up to 7 candidate for winglets and the commercial aircraft enter service. tion Partners’ winglet application Given the high demand, Avia- percent, boost range as much as 180 nm, augment cruise speed by 18 knots, improve climb to alti- tude with 2,000-feet-higher initial cruise levels and also enhance handling characteristics. As of March 1, the price for putting winglets on the Hawker 800 (to upgrade it to the so-called 800 SP standard) increased by al- most 8 percent to $425,000. The same price applies to wingletting the Hawker 800XP model (to make it the 800XP2). Aviation Partners already has more than 40 orders for these upgrades. European Installation Center Considered The burgeoning business may be a factor behind Clark’s desire to establish an offshore winglet installation center in Europe, pos- sibly with Switzerland’s Jet Avia- tion. An earlier plan to appoint that company foundered when the Bringing New Goals Within Your Range initial customer withdrew at a late stage after winglets had been shipped to Europe. Clark would not specify which countries outside Europe might next approve the winglet installa- tion, after the European Aviation 4 Global Express Safety Agency certification was re- ceived last year. He said only that 4 11 Passenger Capacity there is a market wherever Hawker 4 800s are operated and that Aviation 12 Hours Range Partners is in talks with potential 4 Based in Geneva customers in seven countries. Brazil and South Africa are likely early candidates, followed by Australia, India and Saudi Arabia, he suggested. Clark said that obtaining formal airworthi- ness approval has become “a straightforward exercise.” However, he added that winglet research and development is ex- pensive. For example, Aviation Partners invested some $30 mil- In many instances, commercial air travel just won't do. Flexible schedules, direct routes and non-stop flights, time lion to bring the BBJ equipment savings, and hassle-free travel are just some of the advantages private charter can offer. And with aircraft such as the to certification. “You don’t just fit Global Express based in Geneva, cities as far afield as San Francisco, Singapore, Rio and Moscow are just one flight the winglets–you redesign the away. aerodynamics of the whole wing. It’s pretty sophisticated,” he said. But the operational rewards With a global fleet of over 50 aircraft, ranging from Citations to VIP-configured Boeing 757, and a market leading also are impressive. Clark proj- reputation for safety and security, we offer highly personalised, competitively priced private air travel for the world's ects that through the use of Avia- most demanding businesses and individuals. tion Partners winglets, operators will save 110 million gallons of fuel this year and 150 million gal- Call +41 22 929 6730, or contact us at [email protected] lons next year. Assuming the www.privatair.com company delivers 400 blended winglet shipsets during 2005-10, Clark estimates that the overall Private Charter - Private Airline Services - Ground Services - Aircraft Management & Sales fuel savings in this decade could reach about 1.2 billion gallons.