ATA Engineering Successfully Completes On-Engine Testing of “Drag-on-Demand” Technology http://www.ata-plmsoftware.com/ata-engi ... echnology/


[youtube]https://youtu.be/EDOSVnW0HnQ[/youtube]

That's pretty neat looking.

In what ways is it better/worse than the bucket style reversers?

It's not a substitute for reversers, it's for noise reduction. It reduces useful idle thrust, producing a braking effect in flight. Their purpose appears to be to allow aircraft to fly in a cleaner configuration, and/or at steeper approach angles, while keeping thrust, and thus noise, to a minimum.

Let the debate of the wisdom of this commence.

Ah ha. Cool. (mea culpa, I should've actually read the linked article! )

Seems like a good idea to me. Increased options to achieve various types of aircraft performance is never a bad thing in my estimation.

Here is some more information:
http://www.popularmechanics.com/flight/ ... ine-brake/

I don't understand the benefit of this idea. The author of the PM article seems to think that flaps and slats are deployed solely to increase drag on approach and doesn't seem to understand that drag isn't the primary goal (if it's a goal at all). And IME the primary noisemaker on a descending jet is the engines, not the aerodynamic noise generated by flaps, slats, and landing gear.

There is a requirement to add drag in final approach so the engine power can be maintained at a high enough level that they will spool up quickly if needed but it's my understanding that this is far less of an issue with modern jets than it was in the past. And maybe this "Air Brake" is really just a way to reduce engine noise in the landing configuration but dispersing the sound but that's not at all clear from the article.

They also mentioned that this somehow saves fuel and I don't get that at all.

If you can descend steeply in a clean configuration with the power back you create a smaller noise footprint and use less fuel. It's all about being able to slam-dunk yourself.

Hello Lance,







Two things on this. I will be brief.

First, an engine air brake would absolutely have benifits at high altitudes. The new generation 737's cannot deploy flaps above FL200 aerodynamic reasons. The speed brakes on many large jets, including the 737 are just not very effective.

Now the Beech 1900 I used to fly had a great air brake, it was the props. Anyone who has flown jets and turbo props knows the difference. Night and day.

Second, this would absolutely save fuel. At high altitudes, a large airliner may have to begin the descent profile sometimes over 100nm out. You shorten that profile, you save fuel. Its as simple as that.

But it seems 90% of the time my jet descent planning is predicated on ATC more so than anything else. Wing spoiler / brakes are noisy, shakey and sometimes pitchy so another option would be helpful I guess. But I imagine they cost half the value of most of the jets they would to be installed on.