Helicopters are great and all, but they've got one serious flaw. They're slow as hell, and that makes them easy to shoot down. So welcome the latest attempt at fixing that problem, the Sikorsky S-97 Raider. And it's sleek and black and mean and it goes like a bat. A very angry bat.
Modern helicopters usually have a few basic elements – a fuselage, a main rotor on top, and a tail rotor at the back. That's all well and good for doing things like lifting off and coming down vertically, moving side-to-side, and hovering in one place, but there are limitations when it comes to going fast. Basically, a helicopter's main rotor blade can only spin so fast before it starts breaking the sound barrier, and the shockwave that produces wouldn't be the best for both human comfort and flight.
That means the fastest traditional helicopter in the world, the Westland Lynx isn't actually very fast at all, with a specially modified one holding the speed record at 248 MPH. And you can buy a car made by Volkswagen that goes faster than that.
So over the past few decades aircraft manufacturers have experimented with various designs that can circumvent the traditional laws of helicopter physics. One solution that has actually made it into production is the V-22 Osprey tiltrotor, but it's had some very serious problems that have brought the whole program into doubt with some regularity.
So the next best idea looks like this, the S-97 Raider, which Sikorsky unveiled today at its "Innovations Center" in Florida.
Instead of having one big rotor on the top, meant to handle both the lift that keeps it in the air and the power for forward motion, along with a tail rotor out back to cancel out the massive rotational torque that would normally send the whole thing spinning wildly out of control, the S-97 takes a different approach.
In order to not only cancel out the rotational torque, but to also provide a whole bunch of lift and thrust, the Raider has two main rotors, stacked one on top of the other. They rotate in different directions, so that the whole thing doesn't turn into a flying embodiment of the spin cycle on your laundry machine.
And out back, it's got a big pusher propeller, providing gobs of forward thrust to push it all the way to a maximum designed speed of 270 MPH.
The basic design for such a thing has been around for ages – since 1936, in fact, when Dr. James Allan Jamieson Bennett, Chief Engineer of the Cierva Autogiro Company, first thought of a craft he called a "gyrodyne," but which is now more commonly known as a compound helicopter. The main benefit is a whole bunch of extra speed and range, but the drawbacks include a lot of increased complexity.
But that speed is no joke. The fastest propeller-driven compound helicopter in the world, the Eurocopter X³, holds an unofficial speed record of 293 MPH, which is much faster than the Lynx.
And also, it looks really silly, like someone constantly waving their hands at you, if they replaced their hands with whirling blades of death.
But a production version of the X³ is years away, if it ever sees production. The Sikorsky S-97 is a little bit slower, and speed is a huge advantage on the battlefield.
But in the world of military procurement, speed of development is an even bigger advantage. And it's a the S-97 Raider is a lot further along in development than anything that could come from the Eurocopter X³ program, thanks to its development-mule predecessor, the Sikorsky X2.
The S-97 Raider is the militarized version of the X2, and it's got a whole bunch of modifications over the original, and not just black paint. It's got missiles, too, room for six troops in the back, a system designed to mask the exhaust from the heat-seeking missiles that are the bane of any military chopper's existence, and what looks to be a few radar-evading design cues as well.
Sikorsky isn't saying much on any stealth yet, though, but as we saw from the raid that resulted in the death of Osama Bin Laden, I'm sure the company would have few problems making a truly sneaky version.
As you can probably tell from the paint, the S-97 is being aimed at enticing the kind of procurement people that take care of the Special Forces. Sikorsky doesn't have a contract for production yet, nor does it have anyone to fund full development of the Raider. It's intended for high-speed scouting and light attack, and could be a more survivable replacement for the OH-58 Kiowa Warrior, which has performed well in Iraq and Afghanistan, but is rapidly aging.
The Army wanted to replace the OH-58 with its proposed Armed Aerial Scout program, and the Raider was a big competitor for it, but after Congressional incompetence led to budget sequestration, the whole thing was cancelled as too financially risky.
But who knows? Sequestration is over, and the economy is supposedly roaring back. Sikorsky knows both of those things, and is hoping that this Raider prototype is a big incentive for the Army to bring about a return of the AAS program.
In the meantime they're hard at work at making the Raider a real possibility.
Photos credit: Sikorsky Aircraft, Bernd Brincken