sasbrb@unx.sas.com (Brendan Bailey) (12/04/90)
From: Brendan Bailey <sasbrb@unx.sas.com>
What is auto-rotate for the av-8b? Someone I know said that the av-8b
doesn't have it. Do some have it and some don't or do none of them have
this feature? What capability does this give a plane(harrier?) that has it?
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Brendan Baileymegazone@wpi.WPI.EDU (MEGAZONE 23) (12/05/90)
From: megazone@wpi.WPI.EDU (MEGAZONE 23) In article <1990Dec4.002219.9452@cbnews.att.com> sasbrb@unx.sas.com (Brendan Bailey) writes: > What is auto-rotate for the av-8b? Someone I know said that the av-8b >doesn't have it. Do some have it and some don't or do none of them have >this feature? What capability does this give a plane(harrier?) that has it? I have never heard the term auto-rotate applied to a fixed wing aircraft. Auto-rotation is used by a rotary winged aircraft after a loss of power. You angle the blades downward so the airflow as you descend keeps them spinning and builds up KE. Then when you are in proximity to the ground you reverse the pitch and use the stored KE to provide a momentary lift vector which cushions the impact. The AV-8B would not be able to auto-rotate as it is a rotorless craft relying on vectored thrust from the Pegasus turbofan. It would only be able to glide like a normal fixed wing aircraft. Only autogyros, helicopters, tilt-wing, and tilt-rotor craft have auto-rotation capablity. And only when the wings or rotors are in vertical flight mode on tilt-wing and tilt-rotor craft. Most modern attack and fighter aircraft do not have a very favorable power off glide profile. ############################################################################### # "Calling Garland operator 7G," EVE Email megazone@wpi.wpi.edu # # MEGAZONE, aka DAYTONA, aka BRIAN BIKOWICZ Bitnet Use a gateway. Sorry. # ###############################################################################
jln@elaine19.stanford.edu (Jared Nedzel) (12/05/90)
From: jln@elaine19.stanford.edu (Jared Nedzel) In article <1990Dec4.002219.9452@cbnews.att.com> sasbrb@unx.sas.com (Brendan Bailey) writes: >From: Brendan Bailey <sasbrb@unx.sas.com> > What is auto-rotate for the av-8b? Someone I know said that the av-8b >doesn't have it. Do some have it and some don't or do none of them have >this feature? What capability does this give a plane(harrier?) that has it? Autorotation is the method used to land a helicopter after its engine(s) have failed. As best as I understand it, the method essentially involves managing the rotational energy remaining in the rotor blades. Depending on the helicopter, they will stay rotating for 5-8 seconds after the engine quits. When the engine quits, the pilot flattens the pitch on the rotor blades (to conserve energy) and dives for the ground. At the last minute, the pilot flares, using the stored energy to slow the helicopter. All helicopter pilots are taught autorotation during training. The ability of a helicopter to land in a small area during autorotation significantly helps their safety. As for autorotation in a harrier, I don't see how that could be possible. The harrier does not have rotor blades. The Harrier hovers buy using vectored thrust from the engine. If the engine isn't turning, you don't have any thrust. Like any plane, the pilot could try a dead-stick landing, but I understand that is rather hazardous in high-performance jets. >Brendan Bailey -- Jared L. Nedzel --------------------------------------------------------------------- e-mail: nedzel@cive.stanford.edu jln@portia.stanford.edu
ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) (12/06/90)
From: ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) > What is auto-rotate for the av-8b? Someone I know said that the av-8b >doesn't have it. Do some have it and some don't or do none of them have >this feature? What capability does this give a plane(harrier?) that has it? Well, the AV-8B wouldn't have it because it is not a helicopter! Autorotation is an emergency maneuver used in helicopters: the downward motion of the helicop- ter is used to drive the rotor around by giving the rotor blades a negative pitch angle. The tail rotor is also decoupled. It is the helicopter equivalent of gliding. Autorotation is used when the engine quits. ------------------------------------------------------------------------------- Iskandar Taib | The only thing worse than Peach ala Internet: NTAIB@AQUA.UCS.INDIANA.EDU | Frog is Frog ala Peach Bitnet: NTAIB@IUBACS !
Steve.Bridges@Dayton.NCR.COM (Steve Bridges) (12/11/90)
From: Steve.Bridges@Dayton.NCR.COM (Steve Bridges) In <1990Dec4.002219.9452@cbnews.att.com> sasbrb@unx.sas.com (Brendan Bailey) writes: >From: Brendan Bailey <sasbrb@unx.sas.com> > What is auto-rotate for the av-8b? Someone I know said that the av-8b >doesn't have it. Do some have it and some don't or do none of them have >this feature? What capability does this give a plane(harrier?) that has it? Auto-rotation does not exist for any fixed wing aircraft, only for helicopters. An auto-rotation (or auto as it is sometimes referred to), is done when the motive power to the rotor systems ceases to function (e.g. the engine quits). Since the helicopters derives it's lift from the spinning of the rotor system, when the rotor stops spinning, the helo will drop like a rock (probably with the rotor blades broken off, since they are held rigid only by centripital force when in flight). An auto consists of lowering the collective pitch control (this controls the pitch of the main rotor blades), neutralizing (or feathering) the main rotor blades. In addition, a target airspeed is set by using the cyclic to provide some forward velocity. In the configuration, the rotor system will continue to spin, "storing" energy for hopefully a soft landing. When you are close to the ground, the collective is pulled up, increasing the AOA of the main rotor blades, slowing the descent. In addition, rear cyclic is used to slow the foward velocity. Then a "normal" landing is made, reducing the collective until contact with the ground is made. Note: when I started by helicopter training, we did autos in the first lesson starting from 1000' agl in a Robinson R-22. With it's light rotor system, autos were fast (1500 fpm down, 50-55 KIAS foward velocity). That works out to about 45 seconds to lower the collective, set the airspeed, and look for a place to land. Since the Harrier is an airplane, not a helicopter, it will glide just like any other airplane. -- Steve Bridges | NCR - USG Product Marketing and Support OLS Steve.Bridges@Dayton.NCR.COM | Phone:(513)-445-4182 622-4182 (Voice Plus) ..!ncrlnk!usglnk!uspm650!steve | AOPA #916233 ..!uunet!ncrlnk!usglnk!uspm650!steve| PP-ASEL, AMEL (I want a P-38 type rating)