From Tube And Wing To Just Wing: The Future Of Airliners

August 8, 2021 by Danie Conradie 77 Comments

Airliners have become an unremarkable part of modern life, but unless you happen to be an aircraft enthusiast, you’d be forgiven for thinking the latest Airbus model looks more or less the same as the Boeing 707 that ushered in the Jet Age. But that might soon change, with blended wing airliners looking like the next step in air travel efficiency. In the video after the break, [Real Engineering] takes us on a fascinating tour of the past and possible future of jet airliners.

Contemporary airliners all still follow the same old “tube and wing” design, but have become vastly more efficient. The latest jetliners burn almost 50% less fuel per passenger-km than they did 50 years ago. This is thanks to better engines, improved aerodynamics, reduced weight, and a vast array of other, often invisible changes. However, it’s looking like a more drastic change is needed to keep the progress going, and NASA, Boeing, and Airbus are all betting on blended wing designs to do this.

Blended wing aircraft are basically flying wings, where the cargo-carrying section of aircraft is shorter, wider, and produces lift. This layout can be used to increase the aircraft’s internal volume, and improve aerodynamic losses, by eliminating the tail. Research shows that blended wing design could reduce fuel consumption by as much as 27%. Since load and produced lift are spread more evenly along the entire width of the aircraft, it also reduces the amount of structural reinforcement required for the wings, especially at the root. The large internal volumes also allow other power sources, like hydrogen fuel cells to be used.

Blended wing aircraft are not without challenges. They are inherently unstable and require complex control systems to fly. These control systems depend on sensors, actuators, and software to work properly, and require multiple levels of redundancy. The omission of these redundancies ultimately led to the 2008 crash of a B-2 bomber, and the more recent fatal crashes of Boeing’s 737 MAX airliners. Also, unlike tubular fuselages, blended wing designs are not ideal pressure vessels. However, this is not a major problem thanks to the availability of carbon composite materials to create strong, lightweight structures.

With aircraft technology moving as fast as ever, we look forward to seeing what the future will bring. Whether it’s personal rotorcraft or commercial space flight, it sure won’t be boring.

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Eliminate Vertical Stabiliser With ArduPlane

July 9, 2021 by Danie Conradie 5 Comments

Flying wings are popular options for fixed-wing FPV flying, but they have one rather annoying characteristic: yaw wag. The flying wing will wobble on the yaw axis while flying, and this side-to-side movement is visible on the pilot’s FPV video feed. With a combination of split rudders and ArduPilot, [Think Flight] eliminated wing wag without using any vertical stabilizers.

Yaw wag usually occurs on flying wings that use a pair of small winglets instead of a large vertical stabilizer on the centerline. Split rudders, also known as differential spoilers, can be used for active yaw control by increasing drag on either wing independently. However, this requires very rapid corrections that are very difficult to do manually, so this is where ArduPilot comes in. [Think Flight] used its yaw dampening feature in combination with differential spoilers to completely eliminate vertical stabilizers and yaw wag. This is the same technique used on the B-2 stealth bomber to avoid radar reflecting vertical stabilizers. [Think Flight] also used these clamshells spoilers as elevons.

Using XFLR5 airfoil analysis software, [Think Flight] designed built a pair of flying wings to use these features. The first was successful in eliminating yaw wag, but exhibited some instability on the roll axis. After taking a closer look at the design with XFLR5, he found air it predicted that airflow would separate from the bottom surface of the wing at low angles of attack. After fixing this issue, he built a V2 to closely match the looks of the B2 bomber. Both aircraft were cut from EPP foam with an interesting-looking CNC hot wire cutter and laminated with Kevlar for strength. Continue reading “Eliminate Vertical Stabiliser With ArduPlane” →

Soaring With The Sun: 4 Years Of Solar RC Planes

October 9, 2019 by Danie Conradie 19 Comments

Many of us have projects that end up spanning multiple years and multiple iterations, and gets revisited every time inspiration strikes and you’ve forgotten just how much work and frustration the previous round was. For [Daniel Riley] AKA [rctestflight] that project is a solar powered RC plane which to date spans 4 years, 4 versions and 13 videos. It is a treasure trove of information collected through hard experience, covering carbon fibre construction techniques, solar power management and the challenges of testing in the real world, among others.

Solar Plane V1 had a 9.5 ft / 2.9 m carbon fibre skeleton wing, covered with transparent film, with the fragile monocrystaline solar cells mounted inside the wing. V1 experienced multiple crashes which shattered all the solar cells, until [Daniel] discovered that the wing flexed under aileron input. It also did not have any form of solar charge control. V2 added a second wing spar to a slightly longer 9.83 ft / 3 m wing, which allowed for more solar cells.

Solar Plane V3 was upgraded to use a single hexagonal spar to save weight while still keeping stiff, and the solar cells were more durable and efficient. [Daniel] did a lot of testing to find an optimal solar charging set-up and found that using the solar array to charge the batteries directly in a well-balanced system actually works equally well or better than an MPPT charge controller.

V4 is a departure from the complicated carbon fibre design, and uses a simple foam board flying wing with a stepped KF airfoil instead. The craft is much smaller with only a 6 ft / 1.83 m wingspan. It performed exceptionally well, keeping the battery fully charged during the entire flight, which unfortunately ended in a crash after adjusting the autopilot. [Daniel] suspects the main reasons for the improved performance are higher quality solar panels and the fact that there is no longer film covering the cells.

We look forward to seeing where this project goes! Check out Solar Plane V4 after the break.

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Tacking Against The Sun: Flying A Batteryless Solar RC Plane Is Almost Like Sailing

October 7, 2019 by Danie Conradie 28 Comments

Flying on the power of the sun is definitely not a new idea, but it usually involves a battery between the solar panels and the propulsion system. [ukanduit] decided to lose the battery completely and control the speed of the motor with the output of the solar panels. This leads to some interesting flying characteristics, almost akin to sailing.

When a load tries to draw more current than a solar panel can provide, its output falls dramatically, so [ukanduit] had to take this into account. Using a ATTiny85, he built a MPPT (Maximum Power Point Tracker) unit that connects between the RC receiver and the motor speed controller. It monitors the output of the panels and modulates the speed of the motor accordingly, while ensuring that there is always enough power to run the servos and receiver. The airframe (named the Solar Bear) is a small lightweight flying wing, with a balsa and carbon fibre frame covered with clear film, with the solar cells housed inside the wing. Since the thrust of the motor is directly proportional to how much sunlight hits the top of wings, it requires the pilot to “tack” against the sun and use momentum to quickly get through turns before orienting into the sun again.

If you want to build your own controller, the schematics and software is up on RC Groups. Check out the Solar Bear in action, flown here by [AJWoods].

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Making A Flying Wing With Expanding Foam

April 21, 2019 by Lewin Day 9 Comments

Many radio control aircraft modelers will be familiar with the process of cutting wings out of foam with the hot wire method. The tools are simple enough to build at home, and it’s an easy way of producing a lightweight set of wings without too much hassle. [IkyAlvin] walks a different path, however (YouTube link, embedded below).

Expanding foam is the key here – that wonderful sticky material in a can that never quite goes where you want it to. MDF and foam is used to create a mold to produce the wing forms. It’s then a simple matter of loading floor underlay into the mold to act as the outer skin, and then filling the mold with expanding foam and waiting for it to cure.

The final parts are assembled into a flying wing, and the first test flight is remarkably successful. Using foam overlay as a skin also has the added benefit of providing a sleek silver finish to the aircraft. It goes to show that there’s always room to explore alternative techniques outside of the mainstream. If you’d like to get more familiar with the classic hot wire technique, though, we can help there too. Video after the break.

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Autonomous Plane Flying Across The USA

June 17, 2014 by Brian Benchoff 28 Comments

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Somewhere between San Diego and South Carolina is an unmanned aerial vehicle attempting to make the first autonomous flight across the United States. The plane is electric and requires a landing and battery swap every hour or so, however the MyGeekShow guys are so far the only non-military entity to attempt such an ambitious flight.

The plane making the multiple flights is a Raptor 140 capable of cruising at 75 kph for about an hour before requiring a battery swap. Ground control is an RV, loaded up with LCDs and radios; as long as the RV is within a kilometer or so of the plane, the guys should be able to have a constant telemetry link.

Already the guys at MyGeekShow have pulled off a 52 km autonomous flight, following their flying wing in a car. Even though a hard landing required swapping out the carbon fiber spar for an aluminum one, the plane making the truly cross-country flight is still in good condition, ready to land on a South Carolina beach within a week.

You can follow the trip on the MyGeekShow Twitter. The guys are pulling off an incredible amount of updates and even a few live streams from the mobile command station.

UPDATE: It crashed. Tip stalls aren’t your friend, and undercambered wings exist. Good try, though.