Aero braking vs...

As others have said, very airplane-specific. In the 402, aero braking was actually quite effective and saved brake wear. In that aircraft, you often had to wait until you slowed below 60 knots before bringing in brake application, else you could start a skid. Terrible brakes. I don't remember the ERJ very well, but I recall we didn't use aero braking. In fact, just keeping the nose from slamming onto the ground was tough enough.

Now, I get a slap across the back of the head from the sim instructor if I try to do that. 20-30" of body clearance on landing. Gotta put the nose down or end up sitting across the table from a few suits with a pitcher of water in front of you. :)
 
I've flown with a few people who think its cool to use aerodynamic braking on the RJ. Effective or not, doing that in a plane full of passengers falls into the "things that aren't in our OM that would be hard to carpet dance out of" category should something go wrong. Our performance data doesn't include it, so why bother? In the RJ I'd only think about doing it in an emergency.

In a small plane doing short field landings I think the full aft elevator serves two purposes. 1) it places more of the weight onto the mains and 2) the aft elevator and slightly increased AOA add induced drag.
 
ppragman said:
...
Click to expand...

What he said. Certain 172s may have long since shed the lead weight that balances the nose wheel, and holding it an inch off the pavement on the roll-out will prevent it from going "BUMP BUMP BUMP!" and making your passengers think you blew a tire. Not that I would know.

Just follow Waco's advice and fly taildraggers... (Although I always managed to screw up and get tailwheel shimmy... I can't win. :insane:)
 
mshunter said:
Thats what brakes do. They turn energy into heat. They will get hot when you use them. Just don't get them too hot.
Click to expand...

Hot brakes, as in overheated brakes in mil speak, is what Hacker is referring to. Lots of procedural stuff to do for us with this when it occurs.
 
///AMG said:
Absolutely, if things were out of limits for standing water or x-winds (or above my personal comfort level, which is pretty low right now :) ). It can still be pretty squirrely even below those numbers, so it's a Hornet technique for dealing with that......of course fuel/other considerations could dictate having to go into a civilian field, or an AF field that doesn't have the short field gear rigged as well
Click to expand...

Thats the thing, AFBs that do have arresting gear, normally have the approach/short-field A-gear disconnected; however they should have NOTAMs that, on request, it should take XX minutes to rig. Often times, there's normally one set of unidirectional gear, two sets of bi-directional gear, and another set of unidirectional gear at the departure end. Often, both sets at the approach half of the runway are de-rigged (if they're not the "in the slot" type aka BAK-14). Only times we use short-field gear in the AF is when we're landing with a gear problem or one gear (only times I've seen).
 
There was a big discussion about this on the NBAA boards a few months ago and the outcome was pretty much 50/50 with a slight leaning toward pushing the nose down especially in the heavy jet category (Falcon's etc.).
 
Yeah it's pretty well briefed here to expect that AFB's will not have short field gear except by request, and even then, there can be miscommunication about what you want. Didn't really consider not having unidirectional there though. I'm used to having E28's pretty much everywhere, so that's a good thing to be thinking about.
 
///AMG said:
Yeah it's pretty well briefed here to expect that AFB's will not have short field gear except by request, and even then, there can be miscommunication about what you want. Didn't really consider not having unidirectional there though. I'm used to having E28's pretty much everywhere, so that's a good thing to be thinking about.
Click to expand...

The departure unidirectional, as well as the bidirectional are both usually in battery, primarily for takeoff aborts. The only thing about the unidirectional on the approach end (ie- the opposite direction's departure end a-gear), is you don't want to engage it going the wrong way; hence why it's usually disconnected. The bi-directional for the approach end is usually also disconnected, but takes only XX minutes to hook-up and arm.
 
Italianaviator said:
There was a big discussion about this on the NBAA boards a few months ago and the outcome was pretty much 50/50 with a slight leaning toward pushing the nose down especially in the heavy jet category (Falcon's etc.).
Click to expand...

Falcons are heavy jets? :pirate:

Actually, I always found it funny that Falcons and larger were considered "heavy" business jets, whereas an RJ (at just the same weight) is "just a damn RJ." :D
 
dasleben said:
Falcons are heavy jets? :pirate:

Actually, I always found it funny that Falcons and larger were considered "heavy" business jets, whereas an RJ (at just the same weight) is "just a damn RJ." :D
Click to expand...

Likely because the big Falcons, Global's, etc, are at the top of their class ('business jet'), whereas the RJ is at the near bottom of it's class ('airliner').
 
MikeD said:
The departure unidirectional, as well as the bidirectional are both usually in battery, primarily for takeoff aborts. The only thing about the unidirectional on the approach end (ie- the opposite direction's departure end a-gear), is you don't want to engage it going the wrong way; hence why it's usually disconnected. The bi-directional for the approach end is usually also disconnected, but takes only XX minutes to hook-up and arm.
Click to expand...

Gotcha.....yeah we have been taught to just always go ahead and advise 15-20 mins out if we are going to need the gear. Heard a story recently about a guy doing a dirty single engine bingo to Al Udeid, who needed to take a trap because the engine that was shut down is the one that powers our NWS, brakes and anti-skid. Told them to rig the gear, they took that to mean long field which they said was in battery. Guy touches down, no gear, and proceeds to blow both mains using E-brakes w/o anti-skid and departed the runway. Good lessons to be learned, plus many more for the Hornet community specifically (this was only the tip of the iceberg of what went wrong on this particular flight), one of the better approach articles I've read lately.
 
///AMG said:
Gotcha.....yeah we have been taught to just always go ahead and advise 15-20 mins out if we are going to need the gear. Heard a story recently about a guy doing a dirty single engine bingo to Al Udeid, who needed to take a trap because the engine that was shut down is the one that powers our NWS, brakes and anti-skid. Told them to rig the gear, they took that to mean long field which they said was in battery. Guy touches down, no gear, and proceeds to blow both mains using E-brakes w/o anti-skid and departed the runway. Good lessons to be learned, plus many more for the Hornet community specifically (this was only the tip of the iceberg of what went wrong on this particular flight), one of the better approach articles I've read lately.
Click to expand...

Oddly enough, in 2004 I was at KNZY when an F/A-18 from VFA-151 was making a night bingo from the USS Abe Lincoln offshore. He landed on RW 36 and had a brake malfunction. Dropped the hook but missed the long-field a-gear and went off the end of the runway into San Diego bay, ejecting just after departing the prepared surface. Plane was in the bay for about a week, partially submerged.
 

Attachments

  • 18.jpg
    18.jpg
    13.5 KB · Views: 127
Yeah I hate being one of Those People who act like driving a cessna is a totally different experience than driving a Jeeeeeettttttttt, but in this (one, very limited) case it is. The amount of time involved in landing and braking a Jeeeeeettttttt or even a slick turboprop pretty much precludes any clever aerodynamic tricks. Get it on the ground, get the spoilers/buckets/reverse (if you have them) out, and mash the brakes. By the time you've done that, the aerodynamics keeping weight off wheels are essentially zero. In a 150 at flaps 40, on the other hand, you can take 100ft off your already very short ground roll by aerobraking (imho).
 
MikeD said:
Oddly enough, in 2004 I was at KNZY when an F/A-18 from VFA-151 was making a night bingo from the USS Abe Lincoln offshore. He landed on RW 36 and had a brake malfunction. Dropped the hook but missed the long-field a-gear and went off the end of the runway into San Diego bay, ejecting just after departing the prepared surface. Plane was in the bay for about a week, partially submerged.
Click to expand...

Yeah have heard all about that one. One of our instructors put it this way:

Option 1: take a trap
Option 2: bolter, go around and take another trap
Option 3: crank the other engine and use normal brakes anti-skid
Option 4: bolter, run off the end of the runway into the water and eject
Your choice :)

That all being said, I think I can understand his mindset of being on a bingo and wanting to get it on deck and stay there, but even then, there are some options (and normally at least a few passes worth of fuel on the backside of the bingo profile in reserves)
 
Boris Badenov said:
Yeah I hate being one of Those People who act like driving a cessna is a totally different experience than driving a Jeeeeeettttttttt, but in this (one, very limited) case it is. The amount of time involved in landing and braking a Jeeeeeettttttt or even a slick turboprop pretty much precludes any clever aerodynamic tricks. Get it on the ground, get the spoilers/buckets/reverse (if you have them) out, and mash the brakes. By the time you've done that, the aerodynamics keeping weight off wheels are essentially zero. In a 150 at flaps 40, on the other hand, you can take 100ft off your already very short ground roll by aerobraking (imho).
Click to expand...

Mmmmmhm. And like I said, certain longer aircraft can easily have a tail strike if you attempt to keep the nose up in the air. Bad juju.

The other difference between an old ratty piston and a JJJJJEEETTTTT? I could probably sit there and eat a sandwich while the airplane flies itself down a non-precision approach in VNAV, complaining the whole way that the foot heaters are too hot. That old worn out 402? You're doing the same approach hand-flown, cursing the whole way down about the water that's leaking through your crew hatch onto your arm.

But jets are way cooler. Chicks dig jets. As long as you cancel at the gate.
 
Yeah, to play devils advocate - I did three no-spoiler landings in 1-26 last week. Over the numbers at 100', I touched down at 4000' down the runway or so. And I had to put the boards out then.

Really depends on the airplane, but for most taildraggers - I prefer long wheel landings not using the breaks (cause I change them and the tires)

Landing technique is something I don't think you can generalize too much - do what the procedures call for in what you are flying.
 
drunkenbeagle said:
Yeah, to play devils advocate - I did three no-spoiler landings in 1-26 last week. Over the numbers at 100', I touched down at 4000' down the runway or so. And I had to put the boards out then.
Click to expand...

Urh? :confused: Is it normal to have your spoilers out on short final? What was different that would cause a touchdown 4000' down? The extra 50' over the threshold?
 
From the Airplane Flying Handbook:

http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-6of7.pdf

Read Chapter 15, specifically the last page.

The nosewheel should be flown onto the ground immediately after touchdown because a jet airplane decelerates poorly when held in a nose-high attitude. Placing the nosewheel tire(s) on the ground will assist in maintaining directional control. Also, lowering the nose gear decreases the wing angle of attack, decreasing the lift, placing more load onto the tires, thereby increasing tire-to-ground friction. Landing distance charts for jet airplanes assume that the nosewheel is lowered onto the runway within 4 seconds of touchdown.​


There are only three forces available for stopping the airplane. They are wheel braking, reverse thrust, and aerodynamic braking. Of the three, the brakes are most effective and therefore the most important stopping force for most landings. When the runway is very slippery, reverse thrust and drag may be the dominant forces. Both reverse thrust and aerodynamic drag are most effective at high speeds. Neither is affected by runway surface condition. Brakes, on the other hand, are most effective at low speed...​
Click to expand...

 
mokulele said:
From the Airplane Flying Handbook:

http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-6of7.pdf

Read Chapter 15, specifically the last page.
Click to expand...

That's nice, however it doesn't apply across all aircraft.

My current aircraft touches down about 140 knots, but has smallish tires and no anti-skid. Wheel braking is not effective in slowing the aircraft down above 100 knots, and will build up excess energy causing a hot brake condition.

Thus, if I don't aerobrake on landing (to slow from 140 to 100), I either:

- Blow the tires
- Have hot brakes
- Go off the end of the runway because of the stopping distance.

Here's what the T-38 manual says about normal landing:

4.8. Full-Stop Landing and Aerobrake:

4.8.1. Ensure the throttles are in idle. On a full-stop landing after touchdown, smoothly increase back pressure to attain approximately a 10 to 12-degree pitch attitude for an aerobrake. A technique is to place the boresight cross (F-16 HUD) or the waterline (MIL-STD HUD) slightly above the 10-degree nose-high reference line. Just prior to the loss of stabilator authority, lower the nosewheel to the runway. Aerobrake as appropriate for gross weight (i.e., with 1,000 pounds of fuel remaining, the maximum attitude of 12 degrees can be achieved at about 130 KCAS). Do not aerobrake abruptly—a lightweight T-38 can leap dangerously into the air with speeds at or above the computed landing speed.

4.8.2. Smoothly fly the nose to the runway approaching 100 KCAS. Heavyweight aircraft stopping characteristics are different than lightweight characteristics. The aerobrake can begin at a faster calibrated airspeed, and the nose will settle to the runway sooner following the aerobrake. Because the touchdown airspeed is higher, the stopping distance is longer and the wheel brakes will initially feel less effective. After lowering the nosewheel to the runway, keep the stick full aft to increase weight on the main gear and use cautious wheel braking to prevent possible skidding.
Click to expand...
But, hey...perhaps I should tell all those tens of thousands of pilots who have flown the T-38 that, according to the FAA, they're doing it wrong.
 
You must log in or register to reply here.
Back
Top