Blog Elements : Flight Training Central

Piloting a craft that’s part James Bond, part helicopter, and part blimp

When I learned to fly, some 30 years ago now, I imagined that becoming a pilot would broaden my horizons. It would give me the sky, as well as the ability to travel more easily to places few people ever got to see.

I was right, of course. I’ve flown across the country multiple times in my own airplanes. I’ve seen remote glaciers in Alaska, and even landed on one in the French Alps. I’ve explored places in the Australian Outback that even most Australians have never seen. I’ve flown relief supplies in five different countries in Africa. I even got to fly a blimp from Switzerland to the Athens Olympics in 2004, getting a low and slow view of Europe from 500 feet above the landscape. I’ve even seen the curvature of the Earth from 70,000 feet.

A lot of those horizon-broadening experiences came from the fact that after I became a pilot, I went on to become an aviation writer. But although all of those were amazing adventures and experiences, they all took place in the sky. I never dreamed that learning to fly might open up opportunities for me to explore the ocean, as well. But it did.

One autumn morning, almost three years ago, I was scrolling through a long list of emails that had arrived in my inbox, when one caught my eye. “Chance to pilot a submarine?” it asked. Now, any email that starts with “chance to pilot…?” gets my attention. But a submarine? Ok, you got me. How does one fly a submarine?

The email was from a guy named Bruce Jones, an avid pilot and adventurer (he’s currently building an RV-10, in which he and his wife plan to circumnavigate the globe). But, he explained, his day job was as CEO of a company that builds personal submarines. He said that piloting a sub was very much like piloting an airplane. And seeing as I’d flown a wide variety of atmospheric aircraft, he thought I might enjoy the experience of flying something under sea level, instead of above it.

After thinking about it, I realized he might have a point. After all, as any fluid dynamics engineer will tell you, the air we fly through is actually a fluid. “Oceans of air” is not just a poetic way of describing the sky. It’s also a factual description. So maybe piloting a submarine could have some similarities to flying a plane.

In all honesty, I can’t imagine any pilot turning an offer like that one down, unless they have a deep-seated terror of the ocean. But it took a while for this one to actually pan out. A couple of months ago, however, I finally found myself in a small tender, just off of Nassau, in the Bahamas, on my way out to a 280-foot-long “shadow” boat, which is the yachting industry’s name for the utilitarian, floating hangars that accompany super-yachts and carry all the toys.

The submarine I was going to pilot was a Triton 3300/3 – so named because it can descend 3,300 feet (1,000 meters) underwater, and carries three people. Triton builds a number of different models, from one-to-three person, and capable of diving from 1,000 to 5,000 meters. The company is also currently developing a sub for a customer that will be able to dive the full depth of the ocean, or 36,000 feet.

My image of a submarine, formed by seeing Navy subs and a lot of Hollywood movies, was of a cigar-shaped, windowless torpedo with one or more propellers at the back. The Triton subs could not be further from that image.

Almost all of the Triton subs are acrylic spheres, surrounded by a fiberglass support structure that gives the impression of a very high tech, solid, and brightly colored pool chair. The acrylic sphere nestles gently in between the arms, supported by a back deck connecting it all together (and housing the vehicle’s batteries and support equipment). Entry to the sub is through a hatch at the top of the acrylic bubble, which on the Triton 3300/3 has an inside compartment about 80 inches in diameter.

I asked Bruce about the wisdom of using acrylic as a structural material in a deep-diving submarine. After all, one of the biggest concerns with diving is the immense pressure water exerts on a vessel or person as you go deeper. At sea level, the pressure exerted on a body (human or mechanical) is about 14 psi. At 1,000 meters, the pressure jumps to 16,000 psi. But apparently acrylic has come a long way since the 1970s, and acrylic actually gets stronger under pressure, down to a depth of about 5,500 feet. So although the acrylic that forms the Triton’s spheres is only 6.5” thick, it’s strong enough that the compartment itself doesn’t need to be pressurized. The air inside stays at sea level pressure for the entire dive.

Another advantage of acrylic, as I would discover, is that it has the same refractive index as water… which basically means that underwater, the acrylic material becomes invisible to the human eye. So “flying” a Triton sub feels almost surreal. Okay, it does feel surreal, on numerous levels. But the biggest piece is that, because of the refractive properties of the acrylic, it appears as if you’re immersed directly in the ocean, except you’re sitting in a comfortable chair, in t-shirt and shorts, with music being piped in to the passenger compartment, and a bottle of water (or whatever) at your fingertips.

Welcome to the fantastical world of James Bond, made real.

Of course, unlike aircraft, which can taxi from their hangar to the runway and then take off under their own power, a submarine cannot just roll itself off the side of a ship into the ocean. And they’re heavy, because they have to be at least as heavy as the water they displace. The Triton 3,300/3 weighs in at 17,600 pounds. So except in the case of very high-end super yachts, which have “drive in” underwater garages, the subs have to be lifted off the deck and placed on the surface of the water by a crane. Once it’s in the water, the passengers can be taken out to the sub in a dinghy.

Having said that, a brief squall was passing through just as we started the launch process for my dive, and getting off a big ship into a dinghy bobbing up and down on waves, and climbing aboard a rocking and rolling submarine in the rain is a bit sporting. “Graceful” is not a word I’d use to describe my maneuvering. The good news is, all that rough noise and tumble goes blissfully away as soon as you submerge. It’s actually the opposite of flying, in that sense. It’s bumpy until you take off. Then it all smooths out.

My PIC for the dive was Patrick Lahey, an experienced dive pilot and the president of Triton Submarines. We climbed down into our leather seats (the Tritons are built for comfort) and prepared to submerge. Patrick warned me that most people are so disoriented by the apparent disappearance of the acrylic when the vehicle first submerges that they fall forward. I could well believe it. Visual cues, even if they’re illusions, can be strong triggers. Especially because even the small platform under your feet in the Triton is clear acrylic, so the bottom literally falls out from under you when you dive.

As promised, the change from the surface to the underwater world was dramatic. I consciously sat back in my seat, but it still felt surreal. I had the sensation of being immersed in a 360-degree, surround-sound IMAX movie, looking at fish swimming right by me, with nothing in between us, despite the fact that I was perfectly dry.

The Triton subs get their buoyancy from air tanks in the catamaran booms. To descend, you release the air from those storage areas. To ascend again, you pump in air from a pressurized air tank below the back deck. A separate oxygen tank pipes breathing air into the passenger compartment, and CO2 scrubbers process and recycle the “dirty air” that is expelled.

Control of the sub is provided by four ducted-fan electric motors. There are two motors on the back of the sub, for forward and back motion, and two angled on the sides of the back deck which can be used for up, down, and banking movement, as well as “translational” sideways movement. Trim is provided by the sub’s batteries, which are located beneath each side boom and can be electronically moved forward or aft as necessary to change the sub’s pitch by up to 7.5 degrees up or down.

All of these systems, the overall design, and each production model, are certified against established safety standards. There is no federal agency, but certification is provided by the American Bureau of Shipping, a not-for-profit organization founded in 1862 to improve maritime standards and safety. Triton reports that ABS-certified subs have not had a fatality or serious injury in the past 20 years. This is all reassuring to me as we descend to depths that would crush a human body if the vessel were to rupture.

The big selling point of these vehicles is the view, however, and as we descend, the sunlight from the surface fades. Fortunately, the Triton is equipped with six 7000-degree Kelvin exterior LED lights, which mimic sunlight and bring out the natural colors of things even 2,500 feet below sea level, where rare corals and sponges and creatures like goblin sharks and giant squids abide.

Gadget-happy customers can also order exterior manipulator arms refined enough to pick up toothpicks, robotic vehicles that can scoot out and explore places too small for the sub while streaming back video, or even a radar-guided spear gun. The sub is also equipped with “plug and play” Ethernet capability, which opens up all kinds of custom options. And although GPS doesn’t work underwater, Triton has designed a virtual GPS navigation system for the sub. It uses a mother ship-based transceiver to track the sub’s location relative to the ship, integrates that with the ship’s GPS signals, and sends the resulting navigational information via an underwater radio telephone system to a display in the sub.

Despite the fact that I’d never been in a submarine before, Bruce was right. I felt right at home in the Triton cockpit. Part of it might be the similarity of the acrylic bubble to helicopters I’ve flown. But I suspect it’s also because because these subs were designed by a pilot. Control of the sub is executed through a three-axis joystick with a thumb wheel on the top of it. And almost all of the instrumentation and data a pilot needs is presented on a single multifunction display that looks as if it would be very much at home in an airplane.

Front and center in the panel’s six round-dial instruments is an artificial horizon, with a heading indicator below it. Flanking that are an altimeter (for distance to the bottom) as well a depth gauge (for distance to the surface). There’s even a vertical speed readout. Bruce told me they designed the sub to be intuitive and easy to operate, and I’d say they succeeded––at least in terms of instrumentation and displays.

Ah, but is piloting this vehicle anything like flying an aircraft? Oddly enough, I’d have to say it is. Not an airplane, mind you. But if you took the sensitivity and maneuverability of a helicopter and mixed it with the languid speed, lagging control time, vectoring fan engines, buoyancy and variable ballast concerns of a blimp… you’d have the flying qualities of a Triton submarine.

Like a helicopter, the Triton is really easy to over-control. It’s also a little disconcerting that pushing the stick forward doesn’t make the nose go down, it just makes the sub go forward (or backward, if you pull back). To turn left or right, you twist the stick. If you pull it one way or the other, the nose stays put, but the sub scoots sideways like a crab. (What they call “translational” movement). Vertical movement is controlled by the thumbwheel on the joystick. But you can maneuver the Triton on a dime. We sidled right up to the side of a shipwreck, and cruised up and down along its length, just a few yards away.

Depth perception, I should note, appeared to be a little wacky in the sub, perhaps because of the curved surface between you and everything outside. But objects look closer than they really are. The shark I would have sworn was a midget swimming five feet away turned out to be a normal sized shark swimming 30 yards away. And I would have sworn that we were six inches from the shipwreck, not 10 or 20 yards. But I suppose you get used to that.

That high degree of maneuverability and sensitivity might be helicopter-like. But piloting the Triton also involves not only the ballast and buoyancy issues, but also the slow, floating movement of a blimp. There’s no jarring movement or noise, like there would be in a helicopter. And there’s a bit of a lag between control inputs and vehicle responses, so that takes some getting used to, as well. It’s a very peaceful experience, when all is said and done. You just have to think ahead, and be gentle in your inputs.

As for speed, the Triton only goes about three knots underwater. But as Patrick said, “Speed is the enemy of observation.” And it’s what you can observe, in this underwater bubble, that makes it so utterly remarkable.

“We know more about the far side of the moon than we do about the deep ocean, below where scuba divers can go,” Bruce told me. That means piloting a Triton sub offers the chance for a rare kind of exploring, in a world where there are few unexplored places left. We only went to 600 feet below sea level, because a storm was coming in and we had to get back. But even at that depth, Patrick pointed out, we might very well be the very first humans to see what we were seeing.

“There are close to 100,000 seamounts [underwater mountains] in the oceans, and only about 1% of them have been explored,” he continued. “But if I dove [in a Triton sub] on one every day for the rest of my life, on every dive I’d probably find a new species.”

This remarkable viewing and piloting experience comes at a price, of course. A new Triton 3300/3 sells for about $3.5 million. But then again, that’s less than a new Pilatus PC-12. And even a Pilatus doesn’t take you––at least not intentionally––where no human has gone before.

In aviation terms, expanding your altitude envelope by a mere 600 feet doesn’t generally amount to much. But if that 600 feet is below sea level, it makes a very big difference, indeed.

—

Lane Wallace is an internationally known columnist, author, and speaker. She’s been an editor and columnist for Flying magazine, a columnist for Sport Aviation, and a correspondent for The Atlantic. In addition, she’s written two books on adventure and its life lessons, including Unforgettable: My 10 Best Flights, which is available through Sporty’s Pilot Shop. You can read more of her adventure stories and writing through her website (www.lanewallace.com), or at her blog: www.nomapnoguidenolimits.com.

When I turned 16 and first learned to drive a car, I was taught to always be aware of the fuel status. When it was time to go to the gas station and refuel, there was never any thought though about how much gas to put in – insert the nozzle, set the hold function on the lever, and wait for the auto-shutoff to kick in when the tank was full. Why would I consider anything other than a full tank?

The same held true in my experiences in recreational boating. After heading back to the marina to refuel, I left with nothing short of a full tank. I used the same logic as when fueling my car – I could run the engine a longer time with less visits to the gas station. There was nothing else to consider.

When I learned to fly an airplane though I quickly learned that I needed to throw that logic out the window. Airplanes are more sensitive to weight and loading, and more often than not can’t be operated with the tanks full of fuel on every flight. Every airplane has a limiting maximum takeoff weight specified by the manufacturer, and you’re legally obligated to follow it (common sense should tell you it’s a good idea too). Flying over a manufacturer’s maximum weight leads to degraded performance in flight, and that’s assuming you’re able to get the aircraft safely off the ground in the first place.

Payload in training aircraft varies a good deal between different models. A Cessna 172R Skyhawk, for example, can carry around 450 lbs of passengers and bags with a full load of 53 gallons in the tanks, yielding nearly 5 hours of flying time. That’s pretty generous, considering it would be a challenge for a pilot, training gear and flight instructor to exceed this limit (that might help explain why the Skyhawk is one of the most popular training aircraft ever built). What if you want to take more gear, or another passenger on the flight though? The simple answer is to depart with less than full tanks. If you need to take along an extra 120 pounds, have the tanks filled up to only 30 gallons — this still provides over 2 ½ hours of flying time with reserves.

As you move up to larger aircraft, you’ll find the same principles apply. While you might think that a high-performance jet can carry a full passenger load and still fly with full fuel, that’s not always the case. In fact many jets filled to the brim with jet fuel can only carry 2 pilot crewmembers and maybe a passenger or two before reaching the weight limit. Even if there isn’t a full passenger or cargo load, it’s still not efficient for larger transport aircraft to carry more fuel than needed for each flight segment. The extra weight decreases performance and will increase the amount of fuel needed to complete flight. One exception here is when there is a considerable fuel price difference between the airports of intended use.

Take fuel planning seriously throughout your flight training. Even if you’re flying a C172 loaded full with 5 hours of fuel for every lesson, pay attention to how you manage the fuel. Lean properly on the ground and in the air according to the guidance in the POH, and mentally note the fuel burned for each flight during shutdown. That way when it’s time to maximize the performance of the airplane for longer trips or taking additional passengers, you’ll be very knowledgeable about the expected fuel burn, and can confidently plan to arrive with your required fuel minimums. You’ll also have the right mindset for flying other aircraft that don’t offer the luxury of providing a large payload with the tanks topped off.

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