Siko­rsky/lock­heed ($14.4 mil­lion)

Air & Space Smithsonian - - In The Museum -

Work­ing with Lock­heed Martin’s famed Skunk Works, the Siko­rsky team is of­fer­ing a de­sign whose like­ness can be found only on the Wheel of Mis­for­tune. It’s a tail­sit­ter. The 1950s Con­vair XFY-1 and Lock­heed XFV-1 were Navy-fi­nanced Po­gos: Sit­ting on their tails, they pointed straight up for take off and land­ing. Big counter-ro­tat­ing pro­pel­lers on their noses did the lift­ing. “The poor pi­lot was look­ing over his shoul­der try­ing to land the thing nose-up,” says Linda O’brien, Siko­rsky’s pro­gram man­ager. But that won’t be a prob­lem for Siko­rsky’s Un­manned Ro­tor Blown Wing, which won’t carry a crew and will be flown by com­put­ers. “Au­ton­omy gives a lot of flex­i­bil­ity in fly­ing a ve­hi­cle like this,” O’brien says.

An artist’s ren­der­ing shows an air­craft whose 36-foot wing­span holds two sta­tion­ary pro­pro­tors, each 15 feet in di­am­e­ter and po­si­tioned mid­way be­tween wingtip and cen­ter­line. Be­tween the ro­tors, the wing sports a pod, sim­i­lar to the cock­pit placed be­tween the en­gine na­celles on a World War II P-38 Light­ning. Un­like the P-38, the Siko­rsky VXP lacks py­lons lead­ing to a hor­i­zon­tal tail. In­stead, be­hind each of the pro­pro­tors—or un­der them when the air­craft sits on its tail—is a ver­ti­cal tail at right an­gles to the wing that ex­tends both up and down in hor­i­zon­tal flight.

O’brien says a tail­sit­ter is “the sim­plest way to cap­ture VTOL and speed be­cause there’s no mor­ph­ing of the air­craft. It takes off on its hind legs, so to speak, pitches over, and tran­si­tions into for­ward flight. You don’t ex­pend the weight and sys­tem com­plex­ity to morph or pivot or trans­form the air­plane in any way.” The Un­manned

( Ro­tor Blown Wing is meant to stay that way, but O’brien says the com­pa­nies have con­cepts for “tilt-wing ver­sions of this that you could put a hu­man in.”

Mark Al­ber, man­ager of ad­vanced con­cepts at Siko­rsky and chief engi­neer on the pro­ject, says the air­craft is called the Ro­tor Blown Wing be­cause, given the size of the pro­pro­tors, “there is a very high per­cent­age of the wing that’s be­ing blown by the ro­tor wash.” This pro­vides ex­tra lift that en­ables the craft to have a smaller wing and greater speed. O’brien pre­dicts the air­craft will fly “sig­nif­i­cantly” faster than the min­i­mum 300 knots DARPA re­quires.

DARPA pro­ject man­ager Ba­gai re­fuses to dis­cuss how the win­ner of the com­pe­ti­tion will be cho­sen. Nor will he ven­ture whether the re­sult might meet the “sub­stan­tially ev­ery­thing a bird can do in the air” stan­dard. In some ways, Ba­gai ar­gues, Klemin’s vi­sion was ex­ceeded long ago. Not that many birds can hover, he notes, and none flies faster than the speed of sound. But birds far out­class manned air­craft in ma­neu­ver­abil­ity and, he ad­mits, in the way they can quickly land on a tree branch or tele­phone line.

As for the more prac­ti­cal ques­tion of how much the VTOL X-plane pro­ject will ad­vance ver­ti­cal flight, Ba­gai says, “Whether the types that we’re de­vel­op­ing right now are the con­cepts that darken the skies or it’s a spinoff from that that dark­ens the skies, I think ei­ther way it’s a huge ram­i­fi­ca­tion.” Were he alive, Klemin would surely be pulling for the de­sign­ers to prove Ba­gai right.

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