BAE Systems has made a bit of aviation history by maneuvering the first aircraft in flight using supersonically blown air instead of ailerons or other control surfaces. Taking to the skies over Llanbedr Airfield in Gwynedd, northwest Wales, the wing-shaped Magma UAV makes use of two new "flap-free" technologies that the company says could one day revolutionize aircraft design.
Today, conventional aircraft rely on a complex array of flaps, ailerons, elevators, rudders, and other control surfaces in order to fly in anything other than a straight line. Despite over a century of development, it's a very crude system that is inefficient and depends on complex, expensive, heavy mechanical parts in order to work.
Developed by BAE in collaboration with the University of Manchester and the British government, Magma replaces control surfaces with a simpler "blown air" technology that controls the flow of air over the wings with supersonic puffs of air from the inside.
At present, Magma is testing two variations of "flap-free" technology. The first is called Wing Circulation Control. In this, air from the aircraft engine is bled off and blown supersonically through narrow slots around a specially shaped wing trailing edge to do the same job as the aileron. The second is Fluidic Thrust Vectoring. This involves deflecting the engine's jet exhaust by blowing air inside the nozzle to change the aircraft's pitch.
According to BAE, the Magma technology has the potential to improve both the control and the performance of aircraft that would be lighter, cheaper, and more reliable. In addition, by removing the gaps and edges of conventional control surfaces, the aircraft become stealthier by making them less radar reflective.
"We are excited to have been part of a long-standing effort to change the way in which aircraft can be controlled, going all the way back to the invention of wing warping by the Wright brothers," says Bill Crowther, senior academic and leader of the Magma project at The University of Manchester. "It's been a great project for students to be part of, highlighting that real innovation in engineering is more about finding practical solutions to many hundreds of small technical challenges than having single moments of inspiration.
"The partnership with BAE Systems has allowed us the freedom as a university to focus on research adventure, with BAE Systems providing the pathway to industrial application. We made our first fluidic thrust vectoring nozzle from glued together bits of plastic and tested it on a hair drier fan nearly 20 years ago. Today BAE Systems is 3D printing our components out of titanium and we are flight testing them on the back of a jet engine in an aircraft designed and built by the project team. It doesn't get much better than that."
Source: BAE Systems
Flight control systems are neither complex nor heavy. In essence two cables and a pulley are all that is required to make a system that works. They are also not inefficient. Modern flight control systems have a low drag count. The Ailerons are the primary flight control system, not the flaps as stated in both articles. Actually blown flaps were used on the Blackburn Buccaneer aircraft which was used by the Royal Navy then by the RAF. There were a couple of problems with these that I address in a moment.
Large passenger aircraft like the A380 have hydraulically actuated Flying control units. In fact the A380 uses a fly by wire system up to the PFCU and then hydraulic actuation to move the control surface. One advantage of this system is that all control surfaces are independently operated so that if any part of the system fails the remaining surfaces can control the aircraft to a safe landing.
This BAE blown control surface aircraft has several limitations. Firstly, if the engine stops, there is no control over the aircraft. A Boeing 747 will glide safely over a hundred miles from 30,000 if all the engines stopped. The next problem is the amount of air that you have to draw from the engine to produce this airflow. We all know that that the amount of drag increases exponentially as we go faster, especially towards the speed of sound. This would require a lot larger engine than would normally be used therefore adding in weight that was lost by removing the flight control system. Another drawback of having this larger engine with its high power requirements is the additional use of fuel that would be required again adds into the weight that has been removed, there could also be a wing size increase to accommodate the additional volume. To create this high pressure, high speed air you would need to tap the air from well into the engine which would be hot. You now have a high pressure, high speed, hot air system that needs to run through the aircraft with all sorts of thermal issues as well as protection should the ducting breakdown or get damaged.
Having pointed out all of those issues I must state that do love innovation. Would it be suitable for UAV's? Probably yes, but I do not think it has a place in either military or commercial aircraft. If BAE really wants to develop something that Is simpler and more efficient I suggest that they look at Sir Frank Whittles moving wing aircraft. These wings moved independently or together to control the speed of flight, turning and pitch. If someone got this working I would be seriously impressed.
It is however, a Great idea for aircraft using the Coandă effect and routing air for thrust as well as control of the aircraft but such aircraft don't exist, were never made and tested in the 50's or scene today anywhere. Makes no sense at all to make such a vehicle and should be dismissed entirely! Just forget about it!.
Hot bleed air from the compressor stage doesn't scare me much since they already use it in the air conditioning packs as a source of exchange cooling after being allowed to expand. Some latent heat in such a control system might be desirable to scare ice away from control sources. I'm sure they've got a plan to integrate into the existing exchanger systems to provide that function.
Bleed air is fairly limitless, at least at the volumes something like this would require... not sure it would necessarily warrant more powerful engines.
I get skeptical when, as you mentioned, a fault in one critical system causes a failure in another critical system...newer aircraft with "fueldraulics" systems, using high pressure fuel for hydraulic actuation? Yeah on a basic level of non-duplication of fuel storage and pump requirements, it does open the door to a lot of "flightmare" scenarios I can come up with easily?