[phantom4570]

At 0:21 you can see the thrust reversers have not yet engaged, and watch them engage over the next second or so. Captain Gyro explained in an earlier post that thrust reversers have to be engaged at idle, while a turboprop can reverse the pitch of the prop without idling the turbine. Does the C17 have a military grade engine that allows thrust reversers to be engaged at thrust settings above idle or did they idle them as they landed.

 

[CaptainGyro]

It's just an educated guess, but the C-17 probably touched down with the engines already at idle. It's fairly common in jet transports to begin reducing the thrust when crossing the runway threshold at about fifty feet above the ground and to touch down at idle.

Another factor is that reversers and ground spoilers are frequently inhibited unless the landing gear sensors send a "weight on wheels" signal to the computers controlling the respective functions.

 

[Snake45]

I can't see your video so I don't know what you're talking about, but I can ask my son, who does C-17 for a living now.

 

[phantom4570]

I can't see your video so I don't know what you're talking about, but I can ask my son, who does C-17 for a living now.

Weird. The link is there when I edited the post, it shows when I preview but not after I saved. Here it is without the https part
www.youtube.com/watch?v=HYwFlM3HMuQ

 

[Snake45]

It's just an educated guess, but the C-17 probably touched down with the engines already at idle. It's fairly common in jet transports to begin reducing the thrust when crossing the runway threshold at about fifty feet above the ground and to touch down at idle.

Number One Son says that's true with most airplanes but not C-17. He gave a detailed explanation I couldn't possibly repeat, but basically, you are not correct, sir.

 

[phantom4570]

Hey Snake: Are you perchance using NoScript or another script blocker? I couldn't see my own videos until I unblocked Youtube and Google.

 

[Snake45]

Hey Snake: Are you perchance using NoScript or another script blocker? I couldn't see my own videos until I unblocked Youtube and Google.

No, I'm using straight AOL, specifically AOL Gold, which has been so "improved" it is now virtually worthless. I can see YouTube and Google otherwise on AOL, and from links on other sites, just not on this one for some reason.

 

[CaptainGyro]

Number One Son says that's true with most airplanes but not C-17. He gave a detailed explanation I couldn't possibly repeat, but basically, you are not correct, sir.

There are only three possibilities:

1. Touch down with forward thrust...not logical when you're trying to stop in the shortest distance, but certainly possible.

2. Touch down at idle...the most common practice in heavy jet transports.

3. Touch down already in reverse...evidently possible in the C-17 but not apparent in the video, where we can see reversers deploy after touchdown.

So which of the three does Number One Son say is used?

 

[Snake45]

There are only three possibilities:

1. Touch down with forward thrust...not logical when you're trying to stop in the shortest distance, but certainly possible.

2. Touch down at idle...the most common practice in heavy jet transports.

3. Touch down already in reverse...evidently possible in the C-17 but not apparent in the video, where we can see reversers deploy after touchdown.

So which of the three does Number One Son say is used?

I guess I'll have to ask him again, and take notes. I do remember a couple snippets from the conversation:

"...we're basically flying on the back side of the power curve at that point..."

"...you can actually be at full thrust when you touch down..."

"...it's all basically the exact opposite of the Airbus" that he's currently learning to fly for the airline.

Oh, also, every time I click into this thread, a "Save As" box opens up. It's wanting me to save something as a shockwave flash, or something.

 

[CaptainGyro]

"...we're basically flying on the back side of the power curve at that point..."

OK, this makes sense. Usually, flying slower requires less thrust. But you reach a certain point (L/D max, or the maximum possible ratio of lift to drag) where flying slower actually requires more thrust because your nose is so high (to produce the necessary lift) that your drag goes off the charts. That's what it means to be "on the back side of the power curve".

And he's right, no airliner would ever be justified flying in that regime, but I can see how a military mission might require it.

 

[TommyGunn]

I recall seeing a photo of an F-4 Phantom flying nose up like that as it flew alongside a small civil plane like a Piper or Navion. Phantom pilot must have been having fun .....