Spiroid Wingtip Technology: The best kept secret in aviation?

EXTRA: Listen to the IAG Podcast with Aviation Partners CEO Joe Clark

Imagine an improvement in aerodynamics that might just have the potential to transform aviation.

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Joe Clark, CEO of Aviation Partners, believes he’s got just the thing.

Spiroid tipped wing technology has the potential to save airlines a lot of fuel. Rather than the blended winglet, which has become the standard for all new Boeing 737s coming off the line, a Spiroid tipped wing differs by curving over to create a loop at the end of the wingtip.

According to Aviation Partners, “The Spiroid eliminates concentrated wingtip vortices, which represent nearly half the induced drag generated during cruise.”

The technology isn’t new. In fact, Dr. Louis Gratzer, Vice President of Technology for Aviation Partners has held the patent on the Spiroid tipped wings since 1992. When the winglets first flew on a Gulfstream II, Aviation Partners yielded a 10% improvement in fuel burn.

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In a short-haul environment, a 10% improvement with Spiroid tipped wings could be the stepping-stone to the next-generation in fuel efficiency.

For example, the new Pratt & Whitney Geared Turbofan has touted a 12-15% improvement in SFC (specific fuel consumption). Pratt & Whitney has always affirmed that the 12-15% improvement is separate from whatever gains in efficiency are delivered through aerodynamic refinement of the aircraft.

The coupling of these two technologies could deliver fuel burn improvements up to 22-25%, exceeding even the most optimistic of forecasts without radical changes in engine technology or aircraft configuration that might be required with an unducted fan or blended wing body for example.

From an aerodynamic standpoint, Clark added that the Spiroids arecompatible for any swept wing aircraft. Testing on a Falcon 50 willbegin in 3-4 months to further validate the technology.

“We need to get out and do the full flight test realm. We don’t know what they are going to do in icing and in flutter,” said Clark.

Following the Falcon 50 Spiroid flight tests later this year, Clark wants to test the technology on a Boeing 777. On the longer-range 777s, this would require the removal of the raked wing tips. Boeing’s raked winglets provide a 5.5% improvement in fuel burn over the original 777-200/200ER/300 aircraft.

Boeing has estimated that for every 1% improvement in fuel burn, the 777 would gain 75 nm in range, 10 more passengers or 2,400 pounds of cargo.

A doubling in wingtip efficiency with Spiroids could open the door for new routes for airlines. The famed ‘Kangaroo Route’, the non-stop flight between Sydney and London could finally be in reach. The 777-200LR is able to make the journey one-way, but the route has never been economically viable because of the prevailing winds that limit payload capacity. A 4.5% improvement in fuel burn could, once and for all, open up the route.

Blended Winglets

Aviation Partners launched a joint venture withBoeing to bring winglets to the next generation 737 family. The use ofwinglets has expanded to include the 757 and soon the 767.

Inthe near term, a Boeing 767-300ER equipped with 11-foot tall AviationPartners Boeing winglets is expected to take to the sky for the firsttime for FAA certification test during the second week of July. Theaddition of winglets on the 767 are expected to improve fuel burnaround 5-7%.

The use of blended winglets on short-haul aircrafthas been more challenging because the efficiency gains are primarilyrealized the longer an aircraft is in cruise phase.

In apodcast interview with IAG’s Addison Schonland, Clark discussed that hehis in similar talks with Airbus to bring winglet technology to itsproduct line. Clark was unable to discuss specifics due to anon-disclosure agreement, but speculated that blended winglets on anA380 would be 17 to 18 feet tall.

Even before exploring thepotential of Spiroid tipped wings on the 777, Clark also wants to puthis blended winglets on the long-range twin.

“We have a plan for the 777. I think you’ll be seeing something very shortly,” added Clark.

Clark believes that blended winglets will be flying on the 777 within two years.

“Wethink the 777 will benefit substantially from our technology,” Clark speculated. “The 777is a great airplane and will be around a long, long time. Withthe advance in aerodynamics we won’t really be able to improve the fuelconsumption or reduce the drag by as much as some of the otherairplanes, but we still think it’ll be in the 3-4% range, which is abig number for an airplane like that.”

Clark would love to go head-to-head with Boeing and take the raked wingtips off the 777 and try his own design.

“I’d love to compete with them on that.”

10 Responses to Spiroid Wingtip Technology: The best kept secret in aviation?

  1. Bryan June 26, 2008 at 3:46 pm #

    Very informative, but I’m particularly curious about seeing the spiroid wingtip on an A380, just to see how much improvement in range and cargo it would give it and also I’d like to know if this would make the 767 more competitive with an A380

  2. yoyo June 27, 2008 at 2:11 am #

    These ideas are really old (Prandtls time). They work fine at low speeds (incompressible flow). At cruise speeds, the measured fuel savings are within the error of measurement.

    Today, i could sell snake oil, which would have to be dumped over the wing before each flight.
    ($50 per bottle, 10% dicount for a box of 12, free shipping).
    With the power of extrapolations and footnotes i could proove, every airline would save 200$ fuel for each flight.
    I have just to convince some people, to assign the reduced fuel consumption (due to some other inventions) to my snake oil.

  3. pundit June 27, 2008 at 7:23 am #

    For previous reporting, see Aviation International News archive at ainonline.com

  4. Blackjack June 27, 2008 at 7:30 am #

    A350XWB-900 with spiroid winglets?

  5. ing. Anton Beeckman June 28, 2008 at 9:17 am #

    Very interesting article.

    I just wonder how efficient these Spiroid tipped wings really are; especially on large long haul aircraft, having by nature a very substantial cruise flight.

    When these Spiroids are optimized for cruise flight, what flight behaviour (in terms of wing efficiency and fuel burn) do they invoke during climb and during descend ?

    Is this technology’s fuel efficiency the same, regardless of the flight range or not ? And if not, what are the differences ?

    I’m really looking forward for more information on this subject.

    Especially with regard to the application of this technology on aircraft like the Boeing 777 and the A380.

  6. George July 1, 2008 at 5:42 am #

    I wonder if it is like standard wing tips, where the increase in lift towards the tips will require more structural weight from the bending moment?

  7. The Realist July 10, 2009 at 12:25 pm #

    Boeing tested large winglets on the 747 and ended up going with raked tips instead. The argument is that increasing span is always better than winglets in the tradeoff between reduced drag and increased weight. Don’t expect to see Boeing replacing raked tips with API winglets, ever.

  8. Spi_builder April 10, 2010 at 1:31 pm #

    Im current machining the Spiroid for API, this is going to be an amazing addition on to any plane the pure size of this is insane, you can walk through the loop.

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  10. Inquirer January 18, 2011 at 8:53 am #

    If it is so efficient why nobody is using it yet? With such humongous gains it seems dumb not to do so! Wouldn’t an increased span wing be better (with probably lighter foldable tips to fit airport slots)? Remember that winglets only provide their best gain at high angles of attack, not a condition for long distance flights. Does this ugly contraption has the same characteristic?