Posted on 07/22/2007 12:54:42 PM PDT by BGHater
When there’s no safe escape, call in the Mules: These unmanned aerial vehicles could save lives on the battlefield—and off
U.S. troops are pinned down in a crowded city center. Several are wounded and need immediate evacuation. There are miles of labyrinthine roads and thousands of enemy gunmen between them and the nearest base. The threat from rocket-propelled grenades has grounded the big helicopters.
There's one, final hope for these soldiers: the Mule, a compact, fully autonomous medevac aircraft powered by ducted fans—fully enclosed spinning blades that are smaller and more efficient than conventional helicopter rotors. This concept, created by Israel-based Urban Aeronautics, could revolutionize military and civilian emergency care. Within minutes of troops radioing in their GPS coordinates, two drones dart in at 100 mph and land neatly on a narrow rooftop. The casualties are loaded into pods on the UAV's sides—each vehicle can carry two patients—and the fore-and-aft lift fans speed up for vertical takeoff. Once airborne, a medic's voice, piped in by radio, comforts the wounded soldiers, distracting them from the gunfire outside and the disconcerting notion that their rescuers are robots.
The idea, says 56-year-old designer Rafi Yoeli, is a vehicle that can brave dense forests, urban centers and combat zones where choppers, with their vulnerable rotors, can't. Yoeli, who founded Urban Aeronautics in 2001 after decades with companies like Boeing and Israeli Aerospace Industries, is currently building a prototype, aiming for a first flight in 2009. As an unmanned craft, it's both light and able to risk enemy fire. Yoeli is also trying to make it inexpensive, and civilian and military authorities in the U.S. and elsewhere have already expressed interest in his $1.5-million concept.
The dual-ducted fan configuration used on the Mule is derived from failed "flying jeep" experiments of the 1950s. Those early models were doomed by aerodynamic problems, excessive weight and ducted fans that were too weak. Yoeli relies on new lightweight composite materials, sophisticated autonomous flight software and a patented duct design that boosts the fans' efficiency.
The key is a series of directional vanes on both the top (inlet) and bottom (outlet) of the fans. This type of "vectored thrust" steers the craft using directed airflow instead of control surfaces. "It gives you six full degrees of movement," says Janina Frankel-Yoeli, Rafi's wife and marketing director.
Urban Aeronautics faces several hurdles. "Ducted fans have been around for years," says Bob Behler, a retired Air Force general who once flew medevac aircraft and now works for the MITRE Corporation, which conducts technical research for the government. "They're very efficient, but reliability is questionable with vectored thrust." Nevertheless, Behler says that ducted-fan aircraft are great for urban operations. "You've got to have something that travels slowly and can maneuver around obstructions," he explains. He remains concerned, however, about not having a medical attendant with the patient. Frankel-Yoeli agrees, up to a point. "For regular evacuation, it's certainly not the preferred means," she says. "But if the casualty is in critical condition and you have no other means of getting them help, it's not a difficult question." The biggest obstacle, she contends, is psychological. "The problem is overcoming the natural fear of entering a vehicle without a pilot."
How it Works
CONTROL The Mule uses ultraefficient ducted fans—basically, fully shrouded helicopter blades—to lift off vertically. Vane systems channel thrust in any direction, allowing the Mule to move sideways and forward and backward without rolling. If the front and back rotors change their relative speeds, the result is a yawing movement to the left or right.
TURBINE POWER A single Rolls-Royce 250-C30 turbine helicopter engine powers the counter-rotating, three-bladed fans in front and back. The engine exhausts through the top of the fuselage.
WHIRLYBIRD Enclosed rotors in ducted fans make the Mule less vulnerable to gunfire and permit it to fit into small spaces.
GO FAST In forward flight, louvers in front and back [not shown] open to reduce drag. Mounted fans add power.
SNAP TO Automated fly-by-wire controls are reliable and precise, permitting nimble maneuvers amid obstructions and landings on uneven terrain.
This will work. Unfortunately not today.
Unfortunately, not today.
Just pray you don’t have any serious injuries or you’d not be able to get up, walk to the vehicle, and strap yourself in. Then pray you don’t get shot down in your flying defenseless easy target mobile.
Good Lord- I read a sci-fi series years ago ( David Drake? ) that had “Valkyries” swooping down on the battlefield to treat, or bring back from the dead, warriors.
Though this is close, a better technology might use a fanwing instead of a traditional fan. A fanwing aircraft has a fan that looks something like a wheat harvester, a paddle wheel, or a swamp cooler fan. Strangely enough, it has more lift than a typical fan, or helicopter rotors.
Unfortunately, the fanwing concept was patented by a small British company instead of a large US aircraft company. The design the Brits favor is probably far less efficient than what we could design.
But its biggest advantages are a heavier lift from a similar engine, and it is far quieter than a helicopter. It is also more scalable than helicopter designs, which could provide more of the heavy lift capability the military needs.
With some design work, there might be everything from a small, one or two man lift, to carrying large vehicles.
Way too slow and it's already been tried.
For a given power:
The faster you want to go, the smaller your propulsion area, and the larger your exhaust velocity.
The slower you want to go, the larger your propulsion area, the smaller your exhaust velocity.
That is why missions that require hover have large rotors, like helicopters. Things that have mission that involve high speed dash have small exhaust jets, like rockets.
Things that have missions that cover the spectrum either have a medium size medium velocity exhaust, like the JSF, or have two propulsion systems. It depends on the specific application whether the inefficiency of more powerplants is better or worse than the inefficiency of a less than optimum powerplant in one of both mission phases.
I refer you to the “Wheel of Misfortune” on all the different attempts to make vertical takeoff and landing technologies work.
http://www.aiaa.org/tc/vstol/wheel.html
I’ve got a better idea. Build a similar UAV with plenty of armament and ammunition — like a couple of 7.62mm machine guns and a 40mm grenade launcher with a belt feed. Add on some high quality sighting and targeting hardware.
Then the soldiers can stay safely away from the RPGs, sniper fire, etc. and unleash a swarm of the armed UAVs on the urban combat area. Some wheeled, tracked, and walking fighting robots would be handy too. And maybe a few hundred flying claymore mines for good measure..
I agree with the principles you mentioned, and fanwing would definitely fit into the category of a slower moving hover, but it uses a very different air flow dynamic than rotor blades. It really can’t be directly compared to the other aircraft.
I could even imagine a square aircraft with a fanwing on each side, three fans to give lift and one to give lift and impulse. Guidance would be computer controlled, based on cargo, slight adjustments to fan speed and wing and to correct for any sheer type winds.
Unlike a rotor aircraft, which uses repeated and rough downward thrusts of air, a fanwing fan gives a even and constant stream, so it might be a much smoother ride, as well as quieter.
But the bottom line is lift. Since it can lift more than a helicopter, it could be very useful for rear area operations, especially in uneven terrain.
I can park it next to my nuclear powered flying automobile...
How about an autonomous machine that blows the crap out of th enemy and then kamikazes itself into what’s left of the enemies infrastructure, flown by the same guy that it would have picked up, who is now sitting in an air conditioned bunker 1000’s of miles away, and cannot be even remotely injured, unless it is a RSI from keyboard typing or a papercut...
I figure that it should be manned, but that the human on board need not be the pilot (meat servos are less effective than the germanium-silicon ones we can make).
The lift is easy, and I would note that Maxim solved the lift problem rather a while before the Wright brothers solved the control problem. Having plenty of lift for takeoff is an easier problem than having enough control authority for a gentle landing in a gusty environment (as urban environments often are.)
I think the medic/corpsman on board should still be human.
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