NerdGuy Fridays: Dispatches from a Writer's Brain - M. L. Buchman

NerdGuy #38: Osprey (Cover #1)

Miranda Chase #13, Osprey, arrives Sept 26th.

There are two great Nerd-outs in a single cover! Here's the first.
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One look at the cover and you can see that the Osprey is a very strange bird. Is it a helicopter? Or an airplane? Both yet neither. It takes off and lands like a helicopter (mostly, we'll get into why) and it flies like a plane (again mostly). Actually, it's a whole new breed of air vehicle—a tiltrotor.

The Challenge

Helicopters are great because they can land anywhere that's open. They can also hover in tricky spots and raise and lower things like: air conditioning units, radio towers, evacuees, timber, troops, boats... The list is pretty endless.
Helicopters are a pain in the butt because they: have limited range, and can't go very fast.

Range: Not many helicopters can travel over five hundred miles without refueling. The rare few that can reach over a thousand miles do so by dumping payload in favor of fuel. Jet fuel is lighter than water (or whiskey for that matter) but still clocks in at 6.8 pounds/gallon (0.8 kilos/liter for those of you with the decency to think in metric—everyone in the world except US civilians). Five hundred gallons knocks a lot out of payload limits.

Go Fast: The fastest helicopter in the world prior to the Osprey was the MH-47 Chinook at a heart-stopping 196 mph. And it can carry 12.5 tons of fuel and payload while doing it. That sounds great until you look at your average turboprop supply plane like the little C-2 Greyhound that doubles that at 394 mph while carrying 5 tons over fifteen hundred miles. Or the air force's big cargo jets in the 550 mph range and can deliver Abrams battle tanks halfway around the world. Never mind the jet fighters going Mach 2 or more (they have different priorities).

Eating Your Bacon Too (mostly)

Along comes the Osprey. It takes off and lands vertically (VTOL) but flies like a plane at a respectable 350 mph while carrying ten tons of cargo a thousand miles. Vertical lift, big capacity, and some hustle...a win-win, right? (Mostly.)
Let's bypass the testing phase. This is a drastically new technology, which means that in the beginning it failed a lot and killed a lot of people. And because of its capacity to carry a lot of troops, sometimes it did it in large groups.

Take Off: There are some real issues here, especially early on. Look back at that picture of the MV-22 Osprey on the cover. To shift from helicopter to airplane, the whole engine swivels at the end of the wing. When the rotor is pointed straight up, the engine exhaust is pointed straight down. That's a turboshaft engine, meaning a jet engine with a shaft in the middle to turn things like large rotor blades. That means hot engine exhaust on a massive scale.

This caused some problems. Grass fires if they wanted to land in a field (but that's okay because helicopters never need to do that. Massive brownout clouds from the twin rotors when landing in dusty areas. It also melted runways (even at airshows), before they figured out to do rolling take off and landings. However, they also melted the decks of aircraft carriers and LHDs (landing helicopter dock ships—basically aircraft carriers for helicopters). A rumor has it that one of the big delays of the CVN-78 USS Gerald R. Ford aircraft carrier was that the brand-new boat design didn't account for the heat of a landing Osprey and they had to replace the entire deck.

This problem has been partly addressed through training and partly through new software that does things like slowly tick the engines back and forth when idling on the ground to avoid overheating a single spot, instead spreading the heat out over a wider area.

But How?

MV-22 in flight over Hurlburt Field, FL (USMC)
You can see why they can't land in airplane mode.

So the engines and rotors rotate at the end of the wings as they transition between flight modes.

There are a few catches, as you might imagine. Aside from the heat and brownout thing (also addressed with new flight control software that let's pilots slide into a high hover and then simply notch their way down a few feet at a time until they touch the ground), there are issues with emergency landings.

The bottom line, don't! A single engine can drive both rotors in an emergency through a connecting driveshaft. But if one rotor or that driveshaft itself are damaged, you have to depend on the wings for airlift to land it like an airplane. And those wings, by design, are very small. If a rotor itself is damaged, the aircraft is going down—hard.

There is good news here though.

Safety: Those who follow the news and saw the tragic accident involving an Osprey this week (  and followed all of those early accidents as I did, you might be surprised to learn that during the conflicts in Iran and Afghanistan, they had exceptional safety records.

The Control

Osprey MV-22 Cockpit (©Dash 24)

Look closely at this photo. There is a normally looking cyclic (joystick) that rises up between the pilot's knees.

But for the pilot's left hand there isn't a helicopter's collective (which looks like a car's pull-up-style parking brake on steroids) or the throttle of a fixed-wing aircraft. Instead, there's that big control on a slider. This was a huge innovation and I'd love to know how much debate came into developing it.

There are controls on the head for various functions to meet the HOTAS criteria (Hands On Throttle and Stick). But note that it's mounted on a long slider. Basically, push forward, go fast. Pull back, go slow.

But the real fun, that you can just barely see, is clearer below.

Imagine this under your left hand. Four fingers wrap around the top to the hidden controls marked by the white lettering. A few more controls for quick access with your thumb.

But that bright spot, down in the slot where your thumb could rest so easily is a bright spot. It's a thumb wheel. Roll it forward/down, and the big engines and their rotors tilt forward. Roll it back/up, welcome to helicopter mode.

And how did that end up in the book?

“No need to melt your runway…” Dave nodded to Josh’s left hand, “roll the thumbwheel forward to initiate proprotor transition.”

That was a real problem with the design of the Osprey—one of many things he didn’t like about the bird. He wondered for the tenth time if that’s why he’d drawn this assignment, his well-known distrust of the aircraft. Had someone chosen him to make sure this evaluation failed? Focusing on being impartial didn’t help.

Something else would have to get him through this, which he had a month to find.
The tiltrotor concept aimed the proprotors aloft like side-by-side helo rotors, one at the end of each wing. Then, once aloft, they tilted them forward so that the Osprey flew like an airplane—one with ludicrously large propellors. When still on the ground they were far too big to start facing forward. But they could be partly tilted, enough to gain some forward momentum, without battering the blades against the ground like the world’s most expensive trench-digger.

The Bell Boeing design didn’t hinge the proprotor itself. Instead, they’d mounted the engine at the very end of the wing and rotated the whole engine-proprotor assembly. Therefore, during VTOL—vertical takeoff-and-landing—operations, the rotor and engine were aimed straight up. This aimed the blazing hot engine exhaust straight down. In the early days, it had melted runways, started grass fires during field landings, and even warped the decks of several aircraft carriers before they learned ways to mitigate that.

Initially, they’d had to put down thick steel plates any time an Osprey wanted to land. Now, when down, the engines were programmed to oscillate a few degrees back and forth so as not to melt the metal decks of ships. Over tar, the answer was to ramp up power after you were already in motion. He still didn’t know how they didn’t start grass fires when landing in the rough.

Josh nudged the knurled knob under his left thumb forward for half a second. The machine responded to the tiny motion of his thumb by angling the seven-meter-long engine—topped by the spinning twelve-meter proprotor—forward about five degrees. Another half second, another five degrees, and she began to roll. He could get to like this. A Merlin’s collective gave no such sense of childhood superhero dreams come true.

“I am become a Viking God.”

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1 comment

Looking forward to getting and reading this book!!

Gaylord Hanson

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