Boeing Dreamliner draws a gigantic outline of a Dreamliner

On Wednesday afternoon, a Boeing 787-800 Dreamliner took off from Seattle on a test flight. Flight tracking apps show the Dreamliner followed a flight path over the United States that draws an outline of the Dreamliner.

It set the internet abuzz, likely one of the goals. But the Dreamliner was actually conducting a flight test of its new Rolls Royce engine "to prove to regulators that the airplane can safely operate on one engine for an extended period of time," according to Flightradar24, a flight-tracking app.

I can’t imagine that would be very fuel efficient

Yes, with one engine out, power still goes to both rotors. There is enough power to maintain level flight at about 80 knots. Of course the one engine is using a little more fuel on one engine, less what the other engine no longer is drawing, then when both engines were online.

I would bet the USMC has figured this out with the 3 engine CH-53E. Shut one down and watch the range go up. The theory is those gas turbines use about the same amount of fuel no matter if you are pulling lots of torque or not. And one less engine

Just really curious what Boeing knew about their flight.

Gee - if that last engine goes out, we might be up here all day, lol

“... I used to argue with my maintenance officer that I could extend the range and ferry distance of a CH-47, if we but just shut down one engine, fly at lower airspeed, yet extend our distance and of course time enroute. I was told I could not do it, as it was en emergency condition. I argued back that I must have been in an emergency every time I flew a single engine Huey.

With one engine out, only half the fuel is being consumed. Adjust for some lack of performance and the range should be increased.”

Doesn’t work that way for a multi-engined fixed wing when it’s one engine inop (with no engines on the centerline of the a/c) because the operating engine is creating a condition of asymetric thrust.

As I’m sure you know, best performance (and usually the best directional control, too) is always in a zero sideslip condition. When you’re all engines operating, wings level and a centered trim ball indicates zero sideslip. But when you’re OEI, the operating engine is constantly exerting a yawing force on the airframe which, left unchecked, will expose more of the a/c’s profile and increase overall drag. So when you’re OEI, because thrust is being applied asymetricaly, zero sideslip in created by trimming to 1/3 to 1/2 of the ball toward the operating engine and banking 2-3° toward the operating engine.

Although it’s the OEI best performance condition, it’s still compromised (compared to all engines operating) because it was achieved by using unbalanced aerodynamic forces to counteract the asymetric thrust. Either AEO or OEI, best range will be at the same Vy airspeed, but drag will always be higher OEI because you’re using opposing forces to null each other out (= loss of efficiency). So shutting one engine down is always going to result in a shortened range, even if you could maintain Vy.

What you suggest might work with a ‘Hook, provided you can maintain your max range airspeed when you’re OEI because OEI won’t result in asymetric thrust. It worked with Rutan’s Voyager (flew around the world on one tank of fuel) because both of its engines are on the centerline (like the Cessna O-2 “Pushme-Pullyou”) and the OEI didn’t result in any asymetric thrust. In fact, they did shut one down when in cruise to extend their range.

If you want to see how one of the best aero engineers yet to draw breath sought to deal with OEI asymetric thrust in a FW light twin (and gain some appreciation for what a compromised condition it is, not to mention how far “outside the box” he thinks), check out Burt Rutan’s “Boomerang”: http://bit.ly/2weUijc

As for the Chinook, I never got a warm fuzzy from flying in any a/c that can have a mid-air collision with itself. :-P

OEI illustrated

The first image shows what naturally happens when one engine craps the bed (unless countermanded from the cockpit).

The second shows why centering the trim ball only compounds your problems when you're OEI.

Profile drag is berry berry bad in either 1 or 2 because the fuselage is flying sideways (relative to direction of flight).

The third shows how "raising the dead" (engine) and out of trim (ball) produces a zero sideslip condition OEI. Dunno why the wings look wonky, might be a 2D effort to show that it's banking toward the operating engine.

Bottom line, in a "conventional" FW twin, powered flight when OEI will always result in asymmetric thrust, which can't help but carry a drag penalty, regardless how you deal with it.

Hey Gore, tell us all about Occidental and your family.

And the zinc mine on his farm in Carthage, Tennessee.

A mine that was known to be polluting the water and soil.

Hometown Paper Exposes Zinc Mine on Al Gore's Property

http://www.foxnews.com/story/2007/03/20/hometown-paper-exposes-zinc-mine-on-al-gore-property.html

Al Gore - Environmentalist And Zinc Miner

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