AFRL seeks drag reduction technology for transports

I first heard about this awhile ago, but it was kept very quiet. The AFRL has been seeking new technology to reduce drag and improve fuel burn for tanker/transport aircraft. They're aiming to use non-invasive technologies to do it, so they're not looking for the obvious answers such as winglets. They're looking for technologies that can be added to areas like the wing root, to smooth the area out and create less drag, without a major overhaul, such as replacing the skin.

The idea is laminar flow control, but the aircraft in question don't lend themselves to that technology, due to the shape of the airframe and wing. So they're trying to control the worst of the laminar turbulence. Some of the technologies include riblets, which control the development of eddies. In 1989, they added riblets to 70% of an Airbus A320, and saw an almost 2% reduction in drag. Other technologies would potentially include dynamic roughness, chemical flow control, smart vortex generators, and plasma heating. Eventually these technologies would become available to the civilian world and commercial aircraft.

Lockheed has studied plasma heating with the C-5M, and sees a L/D increase of 0.5-1% in cruise. This could add up to a potential savings of 3,000 lbs of fuel per flight. A non-recurring cost of $16.5M would refit the entire C-5M fleet.

How do you improve the fuel economy of aircraft that have been in service for years, or decades? Reengining is expensive and unlikely to pay off within the lifetime of older airframes. Modifications to fit winglets can be costly and the return on investment may not come quickly enough.

The U.S. Air Force Research Laboratory (AFRL) is looking for other, less invasive solutions to reducing the fuel burned by the service’s current and future transports and tankers. Specifically, the lab is looking for engineered surfaces, materials and coatings that can be applied to aircraft without substantive changes to the outer mold line that would require lengthy and expensive retrofit and recertification. AFRL wants a fast breakeven and warns that replacing aircraft skins will be too expensive.

The focus is on reducing skin-friction drag, which makes up half the total drag of a conventional tube-and-wing aircraft. Wave and interference drag are other targets. Friction drag can be reduced by increasing the amount of smooth laminar flow over an aircraft, but the dumpy, bumpy shapes of airlifters such as the Boeing C-17 and Lockheed C-130 are not conducive to laminarity, so the lab is looking for ways to reduce friction on surfaces where the boundary-layer flow closest to the skin is turbulent.

aviationweek.com...

How about the rumoured ion assisted flight gear the B2s are said to be fitted with?
Supposedly producing a very fuel efficient effect?
Not exactly sure of the reality.....but apparently the leading edge of the wing is positively charged creating a flow of ions which reduces drag.....
It sounds too good to be true...but commercial aviation would benefit greatly for little cost, if this is true......worth a little research maybe....?

I should think that something like this should fit the bill:

ntrs.nasa.gov...

This algorithm has applications to fighter aircraft, as well. It was tested on a NASA F-18 and has already peaked the Navy's interest.

It's simple. Just spray the airplans with WD-40.

Eveything always works better wih WD-40 ;-p

a reply to: Shadowhawk

Wow, there is a LOT of math and graphs in that link. Lol.

So if I'm understanding it correctly, they are using a new algorithm to adjust control surfaces during cruise flight to reduced drag?

a reply to: Sammamishman

Yes. The algorithm was tested on a NASA F-18 to optimize the aircraft's flight control surface positions for drag reduction. This resulted in as much as 3-percent fuel savings at constant speed and altitude.

The U.S. Navy is investigating how the algorithm might increase the range of the F/A-18E, F and G models. NASA researchers have suggested that it may also be useful for the F-35C, which has more control surfaces than the F-35A and therefore offers more opportunities for fine-tuning trim to minimize drag.

The algorithm has potential applications to larger planes such as tankers and cargo transports, as well as unmanned aircraft. NASA researchers are also studying how to use the algorithm to control trim for one airplane flying in the wake of another to conserve fuel.

This technology could potentially save millions of gallons of fuel and reduce carbon emissions by millions of metric tons for both military and civil aviation.

a reply to: Shadowhawk

Interesting. Seams like this exceeds the AFRL's request for a break even proposal. 3% is huge and I can't image it would be too costly for a new software algorithm script update.

a reply to: Zaphod58

Doesnt less mass = less drag?

If so, instead of adjusting current tech to reduce drag... why dont they just invest in development of material with lower mass, while not compromising other attributes that might affect flight?

Inertia negation?

I may be talking rubbish but it seems like im probs not the first one to say it.

a reply to: combatmaster

Everything causes drag, including paint. The seam where the wings join the fuselage, the engines, the antennas, it all causes drag.

a reply to: Zaphod58

If you have a space ship with the crew compartment enclosed by massive superconducting coils capable of producing truly enormous magnetic fields you could accelerate the ship at ridiculous rates and just use the repulsive magnetic fields to compensate. Humans on board wouldn't feel a thing.

If you work at the atomic level it could be manipulated i reckon.

a frog levitating in a magnetic field of 10 tesla. The reason he levitates is that magnetic field lines prefer to move through vacuum as opposed to water (which makes up most of his body). This means the magnetic field softly pushes him away. The same would happen to a human if you put him in such a strong magnetic field.

ETA i am just pulling at straws... i dunno really what im talking about, im no scientist, but it seems that pretty much anything is possible in science today...

sorry if im just wasting ur time zaph.