Who needs windows when you can have superefficient transonic passenger flight? That seems to be the reasoning behind Otto Aviation's Phantom 3500 jet aircraft that dumps the portholes in favor of super-laminar flow to lose weight and burn less fuel.
Ask an aerospace engineer what they honestly think of windows on an aircraft and you'll get a look more suited to Captain Ahab discussing Moby Dick. In other words, engineers don't like windows. They really don't like them.
That's because the ideal aircraft fuselage should be a seamless cylinder. Putting in windows violates the structural integrity of the hull, producing weak spots where stresses can concentrate. They also add weight, reducing fuel efficiency. Then there's the fact that windows mess with the flow of air over the skin, increasing drag.
And all that has to be endured just because sealing passengers into a cylinder with no way to see out might give them a panicky case of the claustrophobic screaming meemies. No consideration for the engineer there!
Based on flight tests by Otto's Celera 500L prop-driven prototype and Dassault Systèmes' 3DEXPERIENCE platform, the Phantom 3500 hopes to achieve an initial increase in fuel efficiency of 35% by means of sustained laminar flow. That is, configuring the hull in such a way that air flows over the wings, fuselage, and tail in smooth, parallel layers like a deck of cards sliding smoothly over one another with minimal mixing between adjacent layers. That means the airflow doesn't actually touch the hull and it slides off with little or no friction.
If this can be achieved, especially at the transonic speed zone between Mach 0.8 to Mach 1.2, this can result in reduced drag, improved fuel efficiency with the same performance for less fuel burned, extended range, higher speeds, lighter engines and structural framing, and a smoother ride.
By using advanced carbon-fiber materials to create seamless surfaces on the fuselage to minimize friction, the Phantom 3500 pushes things to the next level and makes many an engineer smile by removing those dratted windows. Instead, there's a smooth, polished hull that the company says is close to the optimum shape for transonic laminar flow.
In case you're wondering where that leaves the four or more passengers in the rather luxurious-looking 800 ft³ (22.65 m³) cabin? In fact, it leaves them with the best view outside of an open cockpit. Instead of portholes that don't get much beyond 10.7 by 18.4 in (27.2 by 46.7 cm) , the Phantom 3500 cabin has seamless, high-definition digital screens running not only on the port and starboard sides, but on the ceiling as well.
I guess that means trading claustrophobia for agoraphobia.
At any rate, the twin-engined Phantom 3500 is projected to have a passenger range of 3,200 nautical miles (3,682 miles, 5,926 km) and a cruise altitude of 51,000 ft (15, 545 m) with targeted costs estimated by 50% below that of comparable aircraft, future fuel efficiencies possibly hitting 50%, and emissions cut by 80%. In addition, its short, wide wings allow it to operate on airfields with runways of less than 3,500 ft (1,067 m). It's even claimed to reduce the creation of contrails, which will please some conspiracy theorists.
"Interesting that the wing design changed radically from the Celera prototype (extremely high aspect ratio and high wing loading) to a far lower aspect ratio, low wing loading designed for STOL," said Mark Moore, Chief Executive Officer at Whisper Aero, on LinkedIn – who was not involved in the project. "Likewise interesting that the propulsion completely changed from a wake ingestion propeller (to help maintain proverse aft fuselage flow) to isolated turbofans. One might think that with these radical changes in aircraft design approach that the Celera approach was abandoned – otherwise why such fundamental and dramatic changes? It’s also strange to see the fuselage appearing to be aluminum instead of composite since composites are so effective at achieving smooth compound curvature without rippling. Any laminar flow aircraft owes a great debt to the great work done on the Bellanca Skyrocket II at NASA Langley with researchers such as Bruce J Holmes . I look forward to analyis (sic) and papers showing why these decisions were made. Best wishes for an exciting product, certainly cruising at 51k feet helps with the drag reduction goal."
The Phantom 3500 is expected to enter service by 2030.
Source: Otto Aviation
