Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

"Thrust Reversers" On The C-17?

Fri Apr 13, 2001 5:40 am

Hi there. First off, to the "Americans" in here, Congratulations!! on the SAFE return "Home" of your 24 Navy Air Crewmen, from China. It sure made my morning!

My question is about the C-17 Globemaster that flew them from Guam to the Hickam AFB in Hawaii, this morning. While watching CNN, I noticed that after the aircraft parked on the ramp and shut down her engines, the "Thrust Reversers" were re-deployed, while the crew members were exiting the left side of the C-17.

Why would the pilot do this to the engines? Could it be to help cool them off?

Why don't all "Airline" aircraft like 747's, DC-10's, Airbus's etc, re-open their thrust reversers once they park at a gate after landing?

Does the type of engines on the C-17 REQUIRE this "Post Landing Procedure"?

Chris

Click for large version
Click here for full size photo!

Photo © Nathan Long




Click for large version
Click here for full size photo!

Photo © AirNikon



Click for large version
Click here for full size photo!

Photo © AirNikon


"Just a minute while I re-invent myself"
 
Wardair Canada
Posts: 28
Joined: Tue Dec 05, 2000 9:39 am

RE: "Thrust Reversers" On The C-17?

Fri Apr 13, 2001 6:06 am

Chris,

The C-17 has a unique reverser system, it is a special kind of system only for the C-17. Since the aircraft is designed to takeoff and land on almost any runway, including unpaved runways, and its a turbofan powered airlifter, if you had conventional reversers found on airliners, you will be kicking up a heck of alot of dirt and that'll be sucked back into the engine and cause millions of dollars in damage. You wouldn't want to pay that kind of bill wouldn't you?

So the reverser system is unique in that when it is engaged, the exhaust is thrusted forward and upwards away from the plane, in other words, no FOD damage. If you study the picture carefully, you can see that the cascaders are blocked underneath but open above...the exhaust is thrust forward and upwards.

With this system, you can keep the engines running and engage the idle reverser system and just immediately begin to load or unload without having to shut down and restart the engine. The C-17 was designed for missions where you land at an airfield, immediately unload and/or load troops and cargo and takeoff immediately. Jet engines take a while to start up and get them up to speed. Its basically a time saving measure and it also prevents your troopers and cargo from being blown all over the ramp. Big grin

Thats why you saw the reversers engaged when the C-17 was parked, its only to prevent jetblast from blowing everything around and you can offload off the aircraft as soon as it stops, instead of having to wait for the engine to spool down before its safe to access the plane.

Airliners on the other hand, they aren't designed to land on unpaved runways, only paved runways and they're usually free of debris, so this kind of reverser system is not quite necessary. Jet engines can only take a certain amount of punishment from FOD before they conk out, but what are the chances of having a really dirty runway at a major airport?

That answers your question, probably more than enough.

Later,

Jason @ CYVR
 
Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: Wardair Canada

Fri Apr 13, 2001 6:34 am

Thanks, Wardair Canada. That was a whole bunch of "Great" information. I appriciate the time and effort you put into typing it out for me. I can see in the photo that the cascaders are open only above, now that you pointed it out to me. Pretty interesting!

So, according to your explanation of how and why the reversers work the way they do, it seems to me that the left side engines must have still been running while the U.S. military personnel were deplaning. Perhaps the C-17 was going to move elseware on the base [under it's own power], after the cerimony.

Chris
"Just a minute while I re-invent myself"
 
Wardair Canada
Posts: 28
Joined: Tue Dec 05, 2000 9:39 am

RE: Wardair Canada

Fri Apr 13, 2001 6:41 am

Chris,

I would think that they engaged the idle reversers and then shut down the engine because if the engines were running and the reverser engaged, it is actually quite noisy and everybody will have their fingers in their ears or be wearing ear muffs. I was watching the homecoming on TV this morning before I left for work, boy it took a while for that C-17 to taxy around  Smile I don't think it was going anywhere soon after.

Jason @ CYVR
 
Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: Wardair Canada

Fri Apr 13, 2001 6:53 am

I agree 100%. As soon as I posted my last response, I thought to myself "Those engines weren't running, you would have heard them over the TV, and nobody would have been able to talk to each other". I understand that they must have engaged the reversers for Safety reasons, because of the amount of people around the C-17 on the ramp.

Don't worry, I'll be OK!

Chris
"Just a minute while I re-invent myself"
 
boomer
Posts: 108
Joined: Thu May 27, 1999 2:59 am

RE: "Thrust Reversers" On The C-17?

Fri Apr 13, 2001 7:08 am

I recall a trick used to aid in starting an engine when there is a stout tailwind. The reverse windmilling fan and spools tend to be a problem with the starter engagement. If the aircraft a needed to park in a strong tailwind, deployment of the T/R (and closing the blocker doors) helps to minimize the fan windmilling backwards.
 
mhsieh
Posts: 327
Joined: Thu Jul 20, 2000 2:28 pm

Rudder/ Nose Wheel Steering

Sat Apr 14, 2001 8:26 am

In the Piper and Cessna that I fly, the rudder moves when I am steering the nose wheel with the rudder pedals. But on jetliners, when the rudder check is being done on the ground, why is it that the nose wheel doesn't turn?
Thanks for your answers.

Who is online

Users browsing this forum: zaphod42 and 17 guests