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Electric Vertical Take-Off Aircraft Successfully Tested By DARPA (newatlas.com)
Slashdot reader drunkdrone tipped us off to some big aviation news:
After several years of development DARPA has successfully completed flight-testing of one of the most novel, and odd-looking, aircraft designs we've seen in some time -- the sub-scale electric X-Plane. After calling for an innovative new approach to an aircraft with vertical takeoff and landing capabilities, DARPA awarded its Phase 2 contract to Aurora Flight Sciences in early 2016. Aurora's design includes 24 electric ducted fans, 18 on the main wings and six on the smaller front canards. Both the main wings and the canards are designed to tilt upwards for vertical takeoff before rotating to the horizontal for regular flight... The prototype was also used to trial a number of other technologies DARPA has been developing, such as 3D-printed plastics for flight structures and aerodynamic surfaces.
The article includes video of the test flight, and reportedly the aircraft also successfully tested "sustained hovering." DARPA will now begin officially developing a full-scale aircraft, which has been designated "the XV-24A."
The article includes video of the test flight, and reportedly the aircraft also successfully tested "sustained hovering." DARPA will now begin officially developing a full-scale aircraft, which has been designated "the XV-24A."
to a few hundred yards.
Probably limiting by the hydrocarbon based fuel carried onboard, per: "A few improvements are slated to be incorporated into the full-scale model, most notably a hybrid turboshaft engine to drive the electric generators powering the fan units, as opposed to simple batteries used in the demonstrator model."
And let us hear what the damn thing sounds like.
“He’s not deformed, he’s just drunk!”
Hopefully the scaled down (from the design target 5 tonne) vehicle will sit in my back yard, get plugged into mains power to recharge itself and take me to work every day.
politicians are like babies' nappies: they should both be changed regularly and for the same reasons
So that we know how that compares to a boat? (knots)
No, so that we know how that compares to other aircraft. Airspeed has been measured in knots since well before you were a gleam in your parents' eyes.
Couldn't you just have stopped yourself before posting such an obvious strawman?
A knot is defined as one minute of geographic latitude in one hour, or a close approximation of it.
My understanding is that this is an accepted means of indicating speed is because it makes for easy translation of speed and distance on common maps. Certainly tradition plays a part but this part it plays is because of how people kept time and measured distance. Since we still use minutes of latitude and hours in tracking distance and time we still use the knot to translate between them.
When traveling at greater heights and distances then other units become more convenient, like mach number and kph. Even then the conversion to knots is almost inevitable since the world is laid out in minutes of arc on most any map you'll find.
I am armed because I am free. I am free because I am armed.
The batteries would be a wash if you removed one of the engines and less fuel might offset a heavier generator.
That does not seem likely to me. We design aircraft with multiple engines because it provides redundancy and convenience. Two engines are nice because they can derive power from a shared energy pool, the fuel tanks. With a single engine and a battery pack the loss of the engine means losing access to that pool of energy that is the fuel.
Then there is the issue of charging up that battery. Given proper infrastructure the battery could be charged from grid power. In the case of remote locations, or emergencies, the grid power cannot be relied upon. In which case the electricity would come from diesel generators and the like. In that case the batteries would be charged from a generator as part of the ground crew tools, have to be charged from the engine on board using fuel while idle on the ground, or whatever. The energy would still come from the fuel but with the additional losses of charging and discharging the battery.
If a battery-turbine "hybrid" plane did suffer a failure of either power plant, the turbine or battery, then parts for both would have to be kept on hand. With a two engine craft a power plant failure would typically mean replacing the engine with one that can fit in either spot. It's the low replacement part count that keeps aircraft like the A-10 in the air. The A-10 has very few parts that are unique to left or right. There is no "left wing" or "right wing" there's just "wing".
A friend of mine worked as ground crew servicing F-16 jets, which has one main engine. A twin engine craft can use power from one engine to restart the other, but a single engine craft does not have that option. There is a battery on board of the aircraft but that is only for navigation and communication. If the engine is in need of restart in the air, or with a lack of proper ground equipment while on the ground, there is a small powerful engine on the plane that can start the main engine. I recall that it runs on hydrazine but I'm not sure about that. Even so there is only enough fuel for the auxiliary engine to attempt two or three engine starts.
The point is that even with an electric drive system the poor energy density of batteries do not make sense to drive the engines. Electric passenger commuter cars can get away with using battery storage because ranges are short and charging stations are easy to find. Not having to get airborne, or stay afloat, helps considerably too.
I am armed because I am free. I am free because I am armed.