Chinook Autorotation

[ORAC]

Engine fire, double engine failure, fire suppression, auto-rotation and safe landing in total brown-out, all in 15 seconds.

Is it true they don't train for Chinook auto-rotation?

Quick-thinking pilot to be recognized for skillfull Chinook landing | Military & Fort Bragg | fayobserver.com (http://www.fayobserver.com/military/quick-thinking-pilot-to-be-recognized-for-skillfull-chinook-landing/article_9397fb59-5c26-529c-b3c7-0abd743ef162.html)

[ShyTorque]

Engine fire, double engine fire, fire suppression, auto-rotation and safe landing in total brown-out, all in 15 seconds.

Is it true they don't train for Chinook auto-rotation?

Quick-thinking pilot to be recognized for skillfull Chinook landing | Military & Fort Bragg | fayobserver.com (http://www.fayobserver.com/military/quick-thinking-pilot-to-be-recognized-for-skillfull-chinook-landing/article_9397fb59-5c26-529c-b3c7-0abd743ef162.html)

The answer was in the report, despite the usual media errors and exaggerations. The key word was simulator.

[bcgallacher]

Just a small point - where did the dust cloud come from if he was in autorotation - there would be no downwash from the rotor. Perhaps when he raised the collective to reduce the descent rate prior to landing? Could a helicopter pilot educate me in this matter.

[Wageslave]

Dustcloud just the same. The rotors still need to provide lift (thus downwash) in the flare, from that point of view nothing changes, its just that the energy to provide lift is taken from somewhere else, ie kinetic energy as opposed to chemical energy.
It probably involves a shorter landing event than a powered landing though so less time for brownout conditions to prevail.

[bcgallacher]

Sounds about right to me - I would think that the dust would be considerably less in volume and duration than with power.

[Rosevidney1]

Whilst in the AAC I asked our US exchange officer how the Chinook handled in autorotation (he had flown the A model in Vietnam iirc.) His reply was "Real stable all the way to the impact site, man".

[212man]

if he was in autorotation - there would be no downwash from the rotor

If there is no downwash from the rotor, the aircraft would be in free fall!

[bcgallacher]

If that is the case how does an auto gyro fly? The airflow through the rotor is upwards.As is the airflow through an auto rotating helicopter rotor.

[John Eacott]

bcg, autorotation in any helicopter is energy management, without power. An autogyro has power from the forward thrust of the engine, so a different kettle of canaries.

Regardless of rotor configuration a helicopter in auto has height, airspeed and rotor RPM (RRPM) as three 'reservoirs' of energy which are traded off against each other to bring the machine into a low/zero speed touch down with airspeed and height traded off to put all remaining energy into RRPM, which is then bled off to reduce ROD and cushion the touchdown. That cushioning would increase the thrust from the rotors and create a downwash.

The article describing the incident is a journalistic exercise and shouldn't be taken as an accurate report; not least because there would have been two pilots sharing the load, not (as implied) CWO Abshier imitating a one-armed coat hanger who 'cut off the fuel/release a suppressant into flaming engines to prevent a mid-air explosion'. Later he is reported as having 'yanked the nose up', etc: really?

[SilsoeSid]

Just 15 seconds passed between the distress call and the dusty, clunky landing on the rocky countryside of Afghanistan.

In that time, Chief Warrant Officer 3 Joseph Abshier had to cut off fuel and release a suppressant into flaming engines to prevent a mid-air explosion as his CH-47 Chinook helicopter fell from 1,500 feet above the foreign terrain.
.
.
.
Without power, the aircraft could fall at 3,000 feet a minute.

1500' in 15 Seconds = 100'/sec = 6,000'/min
:confused:

[ORAC]

Misses out the acceleration from a greater height to terminal velocity (with blades).

[John Eacott]

15 seconds 'from the distress call': not from reacting to the emergency and entering auto. Aviate, navigate, communicate.

Again, it's a newspaper article. When was the last time that you saw one that bore 100% accuracy?

[langleybaston]

QUOTE:

its just that the energy to provide lift is taken from somewhere else, ie kinetic energy as opposed to chemical energy.

Er, no. The enrgy source is potential [courtesy of gravity], the height, traded for kinetic.

[SASless]

Chinook ROD in Autorotation?
About equal to a dropped set of streamlined Car Keys or a Two Dollar Whore's Knickers!

[ORAC]

Well, unless things have changed, the ballpark figure is 2,300-2700fpm, so quoting 3000fpm sounds fair at the altitude in Afghanistan.

http://www.dtic.mil/dtic/tr/fulltext/u2/a151380.pdf

[Chugalug2]

Well done Chief Warrant Officer 3 Abshier. I believe your rank qualifies for salutes from lower ranks, though I may be wrong (I often am!). Whether I am or whether I'm not, your deed gets you a virtual salute from me now, "Longest way up and shortest way down!". There, it's done!

As to the technicalities discussed above I have no idea being by conviction a fixed wings only pilot. It is my firm belief that the Good Lord never meant for wings to go around and around! :=

[The Sultan]

Bet he learned how to auto at Rucker in a TH-67 or Huey. Too bad the new aviators will not as it was removed to keep from smashing Lakotas.

The Sultan

[MightyGem]

imitating a one-armed coat hanger
A one armed paper hanger perhaps?

[Arm out the window]

It's good how the news report says you can shut down a damaged engine and activate the second engine on a Chinook ... very handy.

[langleybaston]

then there was the one-legged loser of an arse-kicking competion ...............

[ShyTorque]

It's good how the news report says you can shut down a damaged engine and activate the second engine on a Chinook ... very handy.

I always prefer to fly around with a spare engine. You never know when you might need to start it up in order to get down again...

[TorqueOfTheDevil]

Very impressive bit of handling. Would be interesting to hear how the fire started and spread so rapidly to the other engine, given that the Chinook's engines are much further apart than most (all?) other twins.