Aircraft

Boeing shows off new transonic wing concept

Boeing is studying the Transonic Truss-Braced Wing concept through a collaboration with NASA as part of the Subsonic Ultra Green Aircraft Research program
Boeing is studying the Transonic Truss-Braced Wing concept through a collaboration with NASA as part of the Subsonic Ultra Green Aircraft Research program
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Boeing is studying the Transonic Truss-Braced Wing concept through a collaboration with NASA as part of the Subsonic Ultra Green Aircraft Research program
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Boeing is studying the Transonic Truss-Braced Wing concept through a collaboration with NASA as part of the Subsonic Ultra Green Aircraft Research program

Boeing has taken the wraps off of a new ultra-thin wing concept designed to improve the performance of transonic aircraft traveling at speeds of Mach 0.8 (593 mph, 955 km/h). The latest version of the company's Transonic Truss-Braced Wing (TTBW) can fly higher and faster than previous iterations thanks to its optimized support truss and adjusted wing-sweep angle.

We hear a lot these days about the return to commercial supersonic air travel and even the advent of hypersonic flight, but the real cutting edge in aerospace engineering at the moment is in transonic flight. Almost all flying outside of military circles takes place in the subsonic realm. That is, speeds under Mach 0.8 (609 mph, 980 km/h). However, in the highly competitive world of commercial passenger and freight hauling, that's not quite good enough.

You might be asking yourself, if the speed of sound is Mach 1 (767 mph, 1,235 km/h), why is subsonic below Mach 0.8? The reason is that the realm between Mach 0.8 and Mach 1.2 (913 mph, 1,470 km/h) is what is known as transonic. That is, the range of speeds just before breaking the sound barrier, and just after that's marked by an increase in air resistance and other factors that can be rough on an airframe.

Ideally, engineers would like to get as close to transonic as possible without pushing the sound barrier, but it's far from easy. That's because it isn't a matter of the whole aircraft going from subsonic to transonic. As one approaches the transition point, some parts of the plane will be over the limit while others will be below it. An example of this is prop-driven fighter planes at the end of the Second World War that would suddenly start to shake themselves apart because they were flying so fast their faster-spinning propellers were breaking the sound barrier.

According to Boeing, the TTBW was originally designed to operate in a range of Mach 0.70 to 0.75 (519 to 556 mph, 835 to 895 km/h), but the new truss, wing sweep, and integrated design allows for better speed and altitude performance by creating a thin, foldable wing with a span of 170 ft (52 m).

The purpose of this is not only to produce a better wing for transonic flight, but also one that is more eco-friendly. It was developed as part of NASA's Subsonic Ultra Green Aircraft Research (SUGAR) program, which aims at creating sub and transonic aircraft that are 71 decibels quieter than current FAA noise standards, have a 71-percent reduction in nitrogen oxide emissions, and burn 70 percent less fuel.

Source: Boeing

12 comments
VincentWolf
The world should just slow down and go with all electric planes.
Joshua Tulberg
Very cool.
Paulinator
Some variants of the AT-6 trainer aircraft from WWII used direct drive engines that pushed their prop tips supersonic. I saw a gaggle of them flying at an airshow once and the only things that got shaken apart were my inner ears. I loved it.
Bob Stuart
Propeller tips routinely go transonic. The shaking of WW II fighters in a dive was due to early transitions on the airframe, as described in the rest of the article.
Pelotoner
It's a good thing fuel consumption is predicted to be 70 lower as those ultra-thin wings and trusses will not hold much.
fb36
Wouldn't extra long wings make things harder at airports? How about biplane approach instead (with shorter wings)? (It could be vertical (one set of wings on top of the other), or, horizontal (one set of wings behind the other)!)
Expanded Viewpoint
Yeah, let's cut the range way down while decreasing the payload at the same time by going all electric! Oh yeah, that makes PLENTY of sense! And those batteries aren't made from any exotic materials now, are they? Just easy to come by stuff that you can buy at any Walmart that don't require lots of energy to refine and then reform into something usable? Uh huh, I don't see any downsides at all to converting ALL modes of transportation to electric drive! Why didn't somebody think of this sooner? There's no reason at all for ever using petroleum products as a fuel source!
J4rH43d
Boeing is not unfamiliar with wing design. The longer a single, straight trailing edge is, the more efficient a wing is. Multiple wings tend to interfere with each other at high speeds. I'm surprised that Boeing accepted the drag and lift penalty the lower truss has..
jerryd
Expanded, is aluminum exotic? As Alum/air batteries have the effective density of jet fuel when you take efficiency into account. Several other chemistries are coming too. Zinc/air is already here. And so much safer than filled with Jet fuel. Same for shipping, taking on some containers of batteries to power the trip. While I like the concept aircraft, a longer cord and less wingspan with good wingtips could do as well on the wing. While thin wings look lighter, they are heavier to make.
DavidB
Yeah, like there's no penalty to continuing to burn fossil fuels for as long as we can still shake the ground apart and pollute the aquifer in our efforts to extract them. Seems to me like someone needs an expanded viewpoint.
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