Slashdot Mirror
First Hover Flight Test of X-50A Dragonfly
kbielefe writes "On Wednesday, flight testing began on the X-50A dragonfly canard rotor wing unmanned aircraft. For those of you not familiar with the dragonfly, its rotors work like a helicopter for takeoff, hovering, and slow-speed manouvering, and then lock into place like a fixed-wing aircraft for cruising. The X-50A's reaction drive makes it "much lighter, simpler and more affordable to operate and support than traditional rotorcraft." And the technology is scalable to larger, manned vehicles. Truly a revolutionary aircraft, with a multitude of potential military and commercial applications." There are some more photos and artwork.
Did you know that in the 50's the Army almost decided not to use helicopters at all after about a hundred soldiers were killed during trials of the Piasecki helicopters? There were people in the Army who were screaming that it was criminal to keep putting men into helicopters.
While I think that the Osprey getting grounded for a year and a half while they fixed the safety-critical problems was appropriate and justified, I'm glad that it's back in the air, and I think that it can really change the face of airmobile combat.
This space for rent.
Does this actually mean something, or is it just a bunch of big words to confuse the general public?
A bit of both.
Conventional helicopters need a tailrotor because main rotor is spun by a mechanism that is fixed to the body of the aircraft which tends to spin the body around too. This thing seems to use a tip-jet mechanism to spin the main rotor, ie the tips of the blades contain little jet nozzles to spin it around and since it isn't mechanically fixed to the body it won't tend to spin the body around too.
Sorry if that didn't as much sense as i wanted it to, i haven't slept in 2 days.
It means that there's nothing inside the vehicle, cranking the rotor around, so the vehicle never tries to crank itself the other way.
This space for rent.
The Harrier has a high rate of failure.
- ha rrier-day1.story
c fm ?Id=303
a ir craft/av-8-variants.htm
http://www.latimes.com/news/specials/harrier/la
"Over the last three decades, it has amassed the highest rate of major accidents of any Air Force, Navy, Army or Marine plane now in service. Forty-five Marines have died in 143 noncombat accidents since the corps bought the so-called jump jet from the British in 1971. More than a third of the fleet has been lost to accidents."
"If the Harrier had been decisive many times in battle, we would all still regret horribly the tragedies of the pilots who have been killed, but at least you'd be able to say that the Harrier made a difference," said Philip E. Coyle, the Pentagon's chief weapons tester from 1994 to 2001.
"What makes this situation so difficult is that we just don't have that kind of battlefield record to support the accidental deaths."
In the Persian Gulf War in 1991, the hot thrust-producing nozzles in the heart of the fuselage -- the devices that allow the Harrier to rise and balance in the air -- made the plane a magnet for heat-seeking missiles. Its loss rate was more than double that of the war's other leading U.S. combat jets. Five Harriers were shot down and two pilots died.
"It's the most vulnerable plane that's in service now," said Franklin C. "Chuck" Spinney, who evaluates tactical aircraft for the Pentagon. "You can't hit that thing without hitting something important."
http://www.nationaldefensemagazine.org/article.
"The AV-8B Harrier--a single-engine attack jet that can take off vertically and hover--has a mishap rate of 12 per 100,000 flight hours, among the highest in the U.S. military aviation community. But only one-third of Harrier mishaps are caused by human error, Dirren said. "Two-thirds [of the mishaps] are related to the aircraft failures."
http://www.globalsecurity.org/military/systems/
"In 1982, after eleven years of AV-8A operational flying, including 55 peacetime aircraft losses, the Commandant of the time (Gen Robert Barrow) asked the Harrier community to address the serious problem of flight safety. The impetus for his concern was "a high mishap rate within the AV-8A community... anticipated continuing turbulence... and a pressing requirement to reduce the mishap rate in order to provide the assets needed for successful transition to the AV-8B." At the time, the community had a cumulative Class A rate of 39 per 100,000 flight hours."
"By 1998, USMC Harrier operations (including Naval Air Systems Command) had resulted in 17 fatalities, one permanent disability and 68 AV-8B aircraft lost. With a cumulative Class A mishap rate of 12.1 per 100,000 flight hours, the AV-8B has consistently outpaced all USMC aircraft types in this statistic."
The FAS website estimates 815 Harriers built in all models all the way from the Kestrel and P.1127 test planes
http://www.faqs.org/docs/air/avav83.html
The Fairey Rotodyne was built nearly fifty years ago. Like the Dragonfly, it used (what was then called) tip-jet rotors, so there was no need for a counter-torque rotor on the tail.
The Rotodyne was advanced technology for its day, but it was killed by the politicians.
whilst it is entirely true that they're FRAGILE (ie: you can shoot most down with a pistol), they are FAR from "flaky". aside from the fragility issue, they are no different from fixed wing aircraft in their "flakiness". they simply trade high speed for the ability to hover, that is ALL. and, incidentally, there is no fix for the speed issue in a conventional chopper, at some "N" speed, the retreating rotor blade stalls and the bird flops over.
most people don't realize that helicopters share EVERY flight characteristic (sans high speed) with a fixed wing aircraft, including the ability to "glide" (they call it autorotation in choppers, the air rushing up through the rotor keeps it spinning, and you flair at the last moment. every helo pilot can do it, and you land without a scratch as long as the surface is apporpriate)
mas cerveza, por favor politically incorrect stu
The biggest problem here was a question of tactics. Army doctrine (now being adjusted) still called for coming to a hover before firing weapons. This obviously exposes the aircraft to high risk small arms fire. Marine doctrine on the other hand has helo pilots firing on the run, not slowing below 60 knots in combat. This difference accounts for much of the combat robustness of the Cobra over the Apache. In fact, before the war, I believe the Marines upped their minimum combat speed.
/. have seen/heard a V-22 approach an LZ at 100 feet AGL in airplane mode. It is nearly silent until a 100 or so yards away. Transition can be quick (15s) land, dump cargo, and transition to forward flight again. Because of this reduced exposure/announcement time, the V-22 is more survivable than an old CH-47 or CH-46.
That said, landing involves stopping, and is always risky. The V-22 has the ability to enter and egress an LZ faster and quiter than any other current rotary wing aircraft. I doubt many on