aerodynamic braking
 

I watched recently a wide body aircraft perform the above maneuver to the extreme and I enjoyed the hell out of the sight. Previously I have not seen it for over a decade (741/742) and even then it was taboo. Understandably the risk of dragging a tail is the factor.

I feel like it may be the last time I will see a hands on aviator in action in commercial aviation. Am I wrong? I would like to hear feedback on the matter and a current view on the procedure.

From my perspective there is no more efficent landing procedure than this.

Poor idea in a wide body--easy to tail strike, better braking with weight on wheels, vastly superior directional control on all gear. Looks fancy, was important in high speed fighters, no place in transport category airplanes.

GF

grounded27
About a decade ago when I was flying 747 classic some of my collegues were doing it and highly recommending it. Somehow I never agreed with this practice. It was not company procedure. No Boeing document supported it. On the contrary the documents stated any delay in putting the nose down increases landing distance. Also it raises the nose very high and is not comfortable for passengers especially in first class. Aerodynamically speaking it defeats the purpose of ground spoilers because while spoilers spoil the lift you keep adding to it by increasing the angle of attack. Maximum braking results when full weight of the aircraft is on wheels. Also the risk of tail strike. If the runway length is plenty to spare or you have no other means of breaking including the accumulator only then may be justified.

Aerodynamic braking will never be approved by FAA or any airline so don't promote it. We all know it would work in an emergency if wheel braking was inop but not for normal ops.

vilas
 

Yes but do not the flaps and high AOA of the wing create/add more drag than the spoilers alone can in this config?

Brakes, aided by spoilers, stop airplanes. Thrust reversers help at high speeds. Having the plane on all gear with the nose wheel steering available makes for directional control. No manufacturer recommends aero-braking for a reason.

GF

grounded27
If drag alone is going to stop the aeroplane it will need a very long RW.AOA also prduces lift which reduces the friction also the aircraft is skimming with minimal contact with the RW. If aerodynamic breaking worked then why would no Airline recommend it? It will save brake wear,save thrust reverser mentainenece. Actually it is recommended to put nosewheel on ground as soon as possible and apply breaking. Aerodynamic breaking is the least efficient procedure.

GF
 

Yes a tail strike. But brakes, spoilers, managed reverse thrust and the full drag of an aircraft in a high AOA skillfull rollout??? I do not question manufacturer or airline policy. It is doubtfull I would hear any modern pilot admit this but I have been in and seen this done with great effect from my simple perspective. I suppose then it is a theoretical issue I question?

So I ask in theory, what do you all think?

Thank you vilas for your 74c input.

From a theoretical point of view, if you have brakes that work it is a complete waste of time.
As GF says, it was used on high speed fighters that had token brakes, so drag chutes and aerodynamic braking on very long runways brought them down to a speed where the brakes could stop them without overheating.
Idle reverse will give you very similar deceleration rates, so you stop just as quickly with no issues of tailstrike/directional control/pax comfort; and if you have carbon brakes then applying them moderately just after touchdown will stop you quicker for no greater cost than if you use them to make the turnoff at 20 knots.
So all in all, it is just as appropriate to transport aircraft as holding it in ground effect after liftoff to accelerate, and "run and break" joins - great fun for the pilot but of no benefit other than to his ego. :E

Come on! It's just for little fun and comfort:)
Keep the touchdown pitch, apply idle reverse and gently lower the nose before you lost control over it. On long RW you will slow down naturally and with cool brakes. Everybody happy. :ok:
Of course you know when to play these games... And, of course, it's nowhere as affective as other braking means.

[YOUTUBE]
They had no choice, but it certainly looks good.

aerodynamic brake and tail cone
 

One of or Captain used to land wit very high pitch,much more than the 12° limit in our books. Once after grounding we had alarm "TAIL CONE".:\ Memory item was to verify if we lost the tail cone. The Captain answerd :"No matter, it is a false alarm".:p I said him again "TAIL CONE" and "we have to verify the tail cone who perhaps is on the RWY". He still was sure it was a false alarm :p, but as I insisted he called the Chief of the Cabin Crew to verify we still had the tail cone, sure it would be a false alarm:p. He called the TWR to inform them we were staying on the Runway to verify the false alarm:p. When the stewardess came back she was laughing and said "we are in a decapotable ".:yuk:
At low speed and high pitch our MD-82 conic shaped tail-cone failed. The new beaver shaped tail-cone of our MD-83s staid connected by a forward depression/lift in the same situation. A truck searched the tail-cone (big and heavy !) in the gras beside the runway where the tail-cone had been rolling. The Tower did not see the tail-cone going away hiden by the fuselage...:sad:
Our plane manual said a tail strike risk exist on landing with more than 12° pitch In fact it was the emergency escape removable tail cone (pulling a handle pulling a connection wire) who was going away.

Sure it's pretty to watch and fun to do;)... but uses a lot more runway, resulting in possible greater brake energy:=, than the lowering the nose to the runway technique rather than letting the nose drop to the runway.

By the way, on a light 727-100 less than 80 kts.:E was my best.

It does look very cool on a big jet, but how far do you risk it:

Well...if you do choose to keep the nose high and aerodynamically "brake" the plane, you must know that plane well. From memories of the A300 (beautiful plane which I loved) there was a "flight idle" still giving good thrust on our General Electric CF6s and a "ground idle" with much lower N1. And that ground idle was obtained...when the nosewheels were on the ground...(I am going to check, but I am pretty sure of it). Nose wheel high...aerodynamic braking...with a lot of thrust on both engines...not ideal certainly?

It seems unfortunate that some manage to confuse braking the aeroplane on landing with breaking the aeroplane on landing. You'd think the difference was so extreme it would be noticed!

Lets hope they restrict this potentially career-ending error to their writing and not to their flying...

NARVAL.

Yes. A300 with CF6-50 will stay in flight idle until the nose wheels are on the ground.

Had a case some years ago when both thrust reversers were locked out and the captain said he would use aerodynamic braking to save wear on the brakes.
I advised that since FI was about 5000 lbs of thrust against less than 2000 lbs thrust at GI it might be better to put the nose wheels on the ground. Common sense prevailed.

Definitely hands on...something! :}

Just to be clear, this aircraft landed, WOW allowed wing engines to deploy (not sure how much reverse thrust was applied but eng's were in reverse) and rolled out a great length with full flaps at a high AOA. Wish my phone was configed to take a quick video. I am no spring chicken, about 20 years in around the flightline or in flight as a back seat driver, doubt they went 1000ft after the nose met the ground. Thank you all for sharing.

Isn't there some sort of concern with regards the elevators running out of sufficient authority to smoothly lower the nose, or a horizontal stabiliser stall, leading to slapping the nose down?

I suppose it comes down to the aviator landing the craft, knowing his/her craft.

When conducting training, I impart that there are two landings made... the main gear and then the nose gear. That said after touchdown, its important to prevent the nose wheel from slamming onto the ground with the proper use of back pressure from not allowing pitch attitude to increase.

The only time aerodynamic braking should be employed on large aircraft.

http://i478.photobucket.com/albums/r...s/IMG_8868.jpg

I seem to recall a 737 accidnt in the US where the last words of the PF before the aircraft ran off the end of the runway were "I'll show you how we used to stop the F4".

This is indeed true.

There might, of course be aerodynamic braking.............

We used to think this worked quite well.......

http://i636.photobucket.com/albums/u...ps24e1dfc7.png

Brilliant LM. Jag used aerodynamic braking on Take Off didn't it?? Got any shots of the Lightning using aero braking?

We do this quite often in heavy aircraft flight test when landing above the brake energy limit, on a long runway, and have no desire to activate the fuse plugs.

The trick is:

Touchdown
Deploy spoilers
Increase pitch attitude to maximum that provides margin from tail strike, say 2 degs less
Derotate before elevator loses effect or runway running out...
Brake

From my notes, around a 1-2kt/sec decel was possible which makes a significant effect on brake energy (much lower due to the v squareds being less)

.. agreed .. but FT is a world apart from routine line flying ?

Even a barbie jet can use up quite a bit of runway ;)

He probably had around 3800 metres to play with ,and it is a looong taxi after that to the terminal,even so looks like 1000+ metres before the nosewheel 'touched down'.

Hi... Nobody has mentioned CofG. For the Broken Nose-Wheel video, if he had moved all the Pax to the rear of the cabin he might have even been able to taxi to the gate with the front in the air !

(Quite what would happen when the first pax steps out is another matter.)

Very lucky to not have a tailstrike... Why would one like to damage their equipment and possribly lose their job?!

Beyond my comprehension!

Jaguar Photo
 

LM,

Great photo. A couple of questions if I may. Did such a high nose attitude delay the full opening of the dragchute due to any disrupted airflow or blanking effect? Was there any significant nose-down trim change when it fully deployed? Just curious, thanks.

+1

If the runway is 4,000m long, your parking spot is at the departure end, all systems are working normally, minimal cross wind, good weather, dry runway, headwind, 747-200F with brakes that tend to get hot (especially landing in the middle east when it's 45C+ outside), competent and experienced flight crew, it is not a big deal. Revers to Idle, get 4 green, add more reverse thrust. It is the difference between parking with brake temps in the amber range or brake temps in the red range. I'm not talking about running the stab trim all the way aft during rollout and trying to get every last bit of elevator authority out of the beast. Having said that, now that I am on the 744 with the carbon brakes I no longer do that procedure nor do the crews I fly with, it is not needed on the 744. Know your airplane, do some of that pilot stuff! Hundred landings in the middle east and never blew a fuse plug, but we would have 1 or 2 crews a year that did. Maybe I was just lucky!

Fire Away :}

Just from curiosity -

I looked up KC-135 landings on Youtube, and couldn't find any aero braking examples. That's not to say it's never done, but probably not encouraged.

Barit1

At least in my part of the USAF, we were taught to put all the paws on the pavement for both braking effectiveness and directional control. And do so BEFORE going beyond reverse idle in case spool up was uneven.

GF

Breaking vs braking
 

Hi
You got it Mate ( lightning),
If you want to finish your linecheck with a bang, tail stike or not, demontrate your skills to your f/o and the lineckr. And voila , you are breaking new ground in the training department. Or not.....?
With regarde to milatary aviation I know nil so I see the point of draging up. ( still not aerodynamic brkn!)
Usefull if you have no brakes, wich I did not have on a regulare bases flying in Ontario in a vee little Cessna 185 on ski and floats...... RTOW and LDA etc was ..... Up to you and your ac.

Lastly as to why we are having this discussion, ?
Live and learn, in the 1980s we did not have internet accses, on pprune, so I read all the reports that Transport Canada published.,with special curiousity about what NOT to do with a Cessna.Useful, still alive!
Back to the future, Boeing and Airbus specificaly states : Dont think about it!
Grounded 27 , we need to go flying together one day!!?
Cheers
Blusdup and out!