Questions for You Aviation and Aerodynamics Experts

a reply to: framedragged

You'd just about have to snort the paint to really get it into your system though. Their range is so limited, that only a few particles would ever get into your system, even over a period of months or even years.

a reply to: Zaphod58

I must be approaching what it's physically doing to the air wrong then. Ie, that it's so radioactive it just ionizes the air around itself passively. Or perhaps faaar less air needs to be ionized than I'm picturing, a film as opposed to a sheath or something. Or maybe there's a way to influence decay rates that never made it out of the black...

a reply to: framedragged

The early systems just used a fairly thin layer around the aircraft, more like boundary layer control than anything. Improvements to stealth were more a side effect than anything else.

a reply to: Zaphod58

Makes sense. My first exposure to the idea was the stealth capabilities so I always pictured an envelope thick enough to really attenuate the signal. Boundary layer makes a lot more sense, what with the much more useful capabilites, especially when the skin can absorb radar just fine on its own.

a reply to: framedragged

We're starting to see boundary layer controls on commercial aircraft for the first time. And there was a VERY interesting RFP for something along those lines for some pretty unusual aircraft a couple of years ago.

787-9 HLFC

a reply to: Zaphod58

Oh that's so cool. From a wired article about it, "The next generation of the idea is active flow control that blows small amounts of air out of tiny “sweeping jet actuators” located just ahead of the rudder. NASA and Boeing recently concluded wind tunnel testing of the design and plan to make inflight tests a few years down the road."

Blowing air at air is just a funny picture.

a reply to: framedragged

It apparently works well though. They saw some interesting results in the certification program. It gets them at least a 1-2% savings by reducing drag on the tail section. The 787-8 already saves 20-22% over a 767, and a little less over a 777. The -9 will save up to 2% over even an -8. That's HUGE for an airline.

a reply to: Zaphod58

In one of the old Boeing/nasa papers about it I saw a theoretical maximum of 15% drag reduction. That's pretty damn impressive for hitting air with air. But even I'd take a 1% reduction on my car, and I only drive like 5,000 miles a year lol. 5000 miles in half a day? Yes please.

it's no 100% reduction, but hey.

a reply to: framedragged

We'll see more as the system is improved and perfected. But yeah, when you're talking the ranges and savings they're already seeing, with the -8, at this point I think 2-3% is the maximum that we're going to see over previous models. If you were to take two older aircraft, like 767-400s, and put this on one of them, I think you'd see 15%, maybe a little more over the unmodified aircraft.