V-22 Osprey aircraft

Cited in passing as the tilt-rotor solution to the Mach-1 blade-tip limit — tilts to airplane mode for 300 mph forward flight. Distinct from the Ship Four crash case treated in §11.

That's why the V-22 Osprey, the Marines' sixty-million-dollar tilt-rotor helicopter, can go 300 miles an hour — because it can tilt. The rotor blades are now in airplane mode, so you don't have the additional velocity of your forward motion, you just have the tip speed. The receding blade is always going less. One blade is going plus your forward motion, the other at the three o'clock position is minus your forward motion. No problem with the receding blade — it's the advancing blade that will set up instabilities and vibrations that'll crash.

Tilt-rotor design rationale — 300–350 mph forward speed, lower acoustic signature than helicopter blades, used in bin Laden raid alongside Blackhawks.

I actually have a picture in here of the V-22 Osprey. The tilt rotor. The two rotors on either end will tilt down, and they used one of these to get Osama bin Laden. You have to understand — does anyone not know why a regular helicopter is limited to about a 200 mile-an-hour forward speed?

Cited as the first aircraft built from composites, and only because no other material would let it fly with usable payload — used to underscore that the aerospace composites community at the time of the DARPA submarine workshop had no all-composite aircraft experience to draw on.

They have this three-day workshop in Reston, Virginia. DARPA has a workshop, and they brought in the aerospace guys, the titanium guys, the old steel guys, and they wanted them to get together and decide how to build the next generation submarine. They didn't care if titanium wasn't the answer. If it was the answer, tell us how to do it. But they brought in a bunch of composite people from the aerospace industry. You have to remember, the aerospace composites industry folks had still not ever designed an aircraft out of composites. The first aircraft out of composites was the V-22 Osprey. The only reason they did that is because they couldn't design it any other way. It would be too heavy. They had to make the Osprey out of composites for it to fly with any payload.

First all-composite major aircraft. Tilt-rotor, 300 mph, used in bin Laden raid. Started at $15M per unit, ended at $65M — "one of the more notable overruns in the Defense Department."

Another aerospace example: the very first all-composite major aircraft. There were small two-seater personal planes that people had made all-composite before, out of fiberglass, but this was the V-22 Osprey, the Marine helicopter. The Air Force has some and the Navy has some, but it was really developed for the Marine Corps. It's a tilt-rotor helicopter — it can fly as a regular two-rotor plane if you tilt the rotors forward, which means it can go 300 miles an hour. Helicopters cannot go 300 miles an hour. Anybody know why? They top out at about 180. It's because the tip of the blade — there's a leading edge and a trailing edge — and when you're going forward at 180 miles an hour and you've got the rotational velocity on top of that, the leading tip gets to supersonic velocities. You get instabilities, your blade falls off, the helicopter comes crashing down. The tilt rotor lets you fly like an airplane and then hover like a helicopter. This was critical in the raid when they got Osama bin Laden — they could come in quietly, not like a noisy helicopter, and then tilt and land in rocky terrain. It was all carbon-fiber composite. It started out supposed to be a $15 million helicopter and ended up $65 million apiece. It's one of the more notable overruns in the Defense Department.

Brief reference back to a prior lecture's discussion: the Osprey could not have flown without high-performance composites. Used as the marquee aerospace-composite example.

We were talking about composites and I just wanted to wrap up a little bit. We use huge amounts of structural composites — concrete for buildings, asphalt for roads — but most of the work done on composites is on aerospace composites, because there are certain things that just can't be built without the lightweight advantages of aerospace composites. I put up the V-22 Osprey before; that aircraft could never have flown if it weren't for high-performance composites.

Cited as the first all-composite aircraft; the design "would never fly" without the lightweight of composites. Mentioned as a candidate topic for student presentations, not developed.

You could take a question like, why did it take so long to introduce composites to aircraft structures? We made aluminum airplanes from the 1940s all the way still today, but we really didn't make an all-composite aircraft until the 1990s. We put composites in aircraft but we didn't make an all-composite aircraft, and that was the V-22 Osprey. The only reason we did that was because that design would never fly unless they had the lightweight of composites. Keep the topic very narrow and focused and you'll do a better job.

First large all-composite aircraft. Graphite-epoxy structure that would have been impossible in aluminum. Used as the high-end ("boutique," thousands of dollars per pound) composite case.

So one thing that gives material scientists a job is they get to try to figure out what the best material is. Composites are wonderful materials. I've shown you my $12,000-a-pound piece of the X-33 space plane. I've shown you this thing of the V-22 Osprey. They could not have built this without composites — graphite-epoxy composites. If they had made it out of something heavy like aluminum, they never could have gotten it to fly. It's the first large all-composite aircraft. They had made smaller little single- or two-person jets out of all composites, but the Osprey was the first one that was all composites.

Cited as the first large all-composite aircraft, ~$60M per unit, all graphite carbon fiber composite. Used to make the structural-materials-in-use point. No discussion of the Ship 2 or Ship 4 crashes here.

[Tom shows images of structural applications.] When we're talking about structural materials, we're talking about things like ships, reactors. All-composite aircraft — this is the first large all-composite aircraft, the V-22 Osprey. The Marine helicopter, about 60 million a pop, is all graphite carbon fiber composite. Could not fly without that material. Try to make something heavy like aluminum — too heavy. So they have to use a very expensive material. This was the X-33 space plane. This is a piece of the X-33 hydrogen tank, fabricated for twelve thousand dollars a pound. It's not very heavy but that's the price.

Tilt-rotor that could not have been built without carbon fiber composite — all-composite by necessity. Cost: $15M → $60M per unit. Cited again in §7 to illustrate that military aircraft economics permit full composites where commercial does not.

First aircraft (1990s) designed with 100% composite structure. Tilt-rotor helicopter where composites were the only path to flyable weight. Also referenced in §3.p6 for its 3,000 psi hydraulics as a comparison point with America's Cup yacht's 7,500 psi.

Over the life of a vehicle, the value of a pound of weight saved is two dollars for automobiles, two hundred for commercial aircraft, and twenty thousand for spacecraft. So it really depends on what industry you're in. If you're talking about shipping, or you're talking about nuclear reactors, they're going to be made out of steel, and I'm going to show you why. If you're talking about aerospace — this is the V-22 Osprey in the experimental version, a tilt-rotor helicopter — this could not have been made without composites. It's made out of carbon fiber composites for the fuselage, the wings, everything. It's the first aircraft, back in the 1990s, ever designed with a hundred percent composite structure. Why? Because helicopters are not very efficient — you have to have a lot of energy to lift a little bit of weight, and the only way to make this thing light enough was composites. You could have made it out of aluminum; it would have been too heavy, never would have flown, wouldn't have had any payload. As it is, you can drive a Humvee into it. You can carry something like 24 Marines in full regalia with their weapons.