[searchingheaven]

Originally Posted by vishy76

Can the autopilot land the aircraft in crosswinds or severe headwinds and tail winds?
Can it counteract winds with the help of the rudder like the pilots do and align the aircraft with the runway shortly after touchdown in a crosswind landing like this one?t

Yes, the autoland system on the 777 is certified up to 25 kts. headwind, 25 kts. tailwind and 25 kts cross-wind. Please note that these automatic land crosswind limit of 25 kts only applies in Cat 2 or 3 conditions. You could in theory let the automatics cope with the tricky crosswind in Cat 1 or better.

Originally Posted by IndiaSierra

I am specifically talking about Visual Approach and not any Instrumental like VOR,RNAV,NDB etc.My question stands that how do you align an aircraft in such a way that after touchdown the noose wheel exactly falls on the center line? Another question,in aircrafts where you do not have a camera on the nose wheel,how do you make the noose wheel stick to the taxiway centerline for optimum wingtip clearance during taxi?

1. This is going to take some time. Stay tuned.

2. Taxiing an aircraft without a camera is not as difficult as it may seem. After a bit of practice, you will easily get it bang in the middle. Consider this synonymous to driving your car. You cannot see the wheels but if I asked you to place the wheel on a line/marker on the road, you would easily do it. How does that happen? Practice and spatial awareness.

Some operators also install strategically placed mirrors which will allow you to see the nose gear position.

Originally Posted by norhog

1. During take off, when the plane rotates, and just lifts off the ground on most of airplanes in tropics between the engine pod and fuselage there is a fat band of white cloud or something formed flowing over the wing. What is that.?

2. On 777, 787 there is a, for lack of correct word, aleoron kind of thing, between flaps and aleoron, that moves very fast up and down and acts as a spoiler on the landing roll period. What is that?

3. There is a small winglets on the external surface of engine pod on the fuselage side, can be seen from the window seat, on a 777, 787. What is its function?

4. What is the power output of a 777 engine in kw and bhp?

5. Any pollution regulations for aircraft engines considering co2 is pumped in upper atmosphere.

Thank you in advance.

Q 1 & 3.

The winglets/fins you are talking about are knows as NACELLE STRAKES/CHINES. Strakes help in increasing the stall angle of attack. The airflow from the engine nacelle affects the main flow over the wing, especially when flaps/slats are deployed. So, when strakes are installed, they act like vortex generators creating a thin layer of turbulence (vortex) over the surface of the nacelle. This vortex trails over the wing re-energizing the airflow and thus increasing the stall angle. Strakes are used if the nacelles are mounted closely under the wing of the aircraft.

The fat band of white cloud that you mentioned is the vortex generated by the nacelle strakes.




Q No. 2

These devices are known as speedbrakes or spoilers. They spoil the lift from the wings, which places the airplane weight on the main landing gear, providing excellent brake effectiveness. Normally, these spoiler/speedbrakes are armed and as soon as a touchdown is sensed by the weight on wheel sensor, these are extended automatically. In case it does not extend automatically on touchdown, we have to do it manually.


Q No. 3
An aircraft’s engines power is not measured in terms of bhp or kw. Thrust refers to the amount of pressure being created for use in forward motion of the aircraft. Therefore, it is expressed in units of pressure like kN or lbf. Horsepower is the total mechanical force being applied to an item i.e. a propeller for the creation of thrust. In basic terms; thrust is output, HP is input. Horsepower and thrust thus cannot be compared. Commercial jets engines work by accelerating a fluid to produce a thrust force, so it is most straightforward to rate these engines in terms of the size of that force. So they are rated directly in pressure units. Theoretically, you could calculate the horsepower generated at a given speed for a set thrust. But it would not be quite accurate.

But since you asked, I will give an estimated figure and calculattion for the 777.

Maximum takeoff thrust = 514 * 2 = 1028 kn.
Engine N1% at crusise speed and altitude = 75%
Thrust produced at this stage = .75 * 1028 = 771 kN
Horsepower = 771 * 253 m/s = 195063 bhp.

A propeller aircraft is designed to perform mechanical work that turns a shaft which is connected to a propeller. The engine itself doesn't produce the thrust, but it turns a propeller that does. So they are rated in terms of bhp. Note that two propeller aircrafts, having the same power output, say 4000 bhp, could produce different amounts if thrust if their propellers were different.

[sagarpadaki]

Fantastic thread searchinheaven! Have been a silent spectator on this thread . The information is beautifully compiled and presented.


I am a huge fan of 777. I purchased (rather bugged my parents to get me) Microsoft Flight Simulator 2003 Professional edition in 2003 (I was just 14 yr old back then!)and have been simming since 2003. 777 was and still is my aircraft of choice. Was doing visual approach for many years until i discovered ILS approach is available in the simulator in 2010 .The sheer grace with which it moves still gives me goose bumps. Have been on an Emirates 777 from DXB to LIRA and was one of the most memorable flights back in 2004.


Have to re-install the MSFS ASAP and get back to flying the 777!


Have few questions - At what point do you guys disable the AP and fly manually on short final? If i understand correctly, when the aircraft is in AP mode with AT enabled and glidescope captured, any input to the yoke will not evoke any change in the direction right? Also is the AT active till touch down? Can AT perform independently of AP?

[norhog]

Thank you searchingheaven for the explanation. Really appreciate the time you take out of your busy schedule to explain all things aviation to us..
But the no2 query, the part I am talking in the trailing part of the wing, sits between the aleoron and flaps. This part is not seen on a 737 or a Airbus A320. I have seen it on 787 and 777.
It seems computer controlled to maintain stability of the aircraft (guessing here ).
I say this because at take off it is sitting lower like flaps. In flight it moves very rapidly up and down as if it is trying to maintain some flying condition. And on landing it is lifted up like a speed brake.
May be I am mistaking some terminology here. Please find my understanding of flight surfaces as below..
1.Sitting at the window seat what I understand as aleoron is on the farthest trailing edge of the wing. It is some what rectangular and moves quite gently.
2. And flaps are on the near side (fuselage side) of the trailing edge of the wing. Squarish and moves in steps gradually as deployed before landing and take off phases.
3. Slats are on the leading edge of the wing almost the entire length. Again operation like flaps.
So this part (part x) sits between the flap and aleoron and is controlled some how to move very fast up and down during the flight, like a flap during takeoff roll, spoiler/ speed brake on landing.
Also the power output as calculated by you is similar to a normal sized LNG ship carrying 160000 m3 cargo doing 20 knots. Size approx 300 meters in length to 15 meters in breadth.
These vessels (any sea going vessel involved in international trade for that matter) have to comply with NOx (nitrous oxide) regulations for engines internationally, and SOx (Sulphur oxide) emission regulations in certain areas of the world.
So airplanes engines having power outputs close to these vessels need to comply with emission regulations.?

[audioholic]

Originally Posted by norhog

But the no2 query, the part I am talking in the trailing part of the wing, sits between the aleoron and flaps. This part is not seen on a 737 or a Airbus A320. I have seen it on 787 and 777.
It seems computer controlled to maintain stability of the aircraft (guessing here ).

I am not a pilot nor related to aviation but just joining this superb thread here. Is it the flaperon you are talking about? The flaperon sits between the two flaps and contributes to the roll movement of the aircraft. Since bigger aircraft need more force to roll around, the ailerons alone will be stressed if the commanded roll is more. And since the ailerons sit at the edge of the wing, it will also put a lot of stress towards the edge of the wing. Hence, since these aircraft are big, they have the flaperon which aids in providing roll and also act as spoilers once the aircraft is on the ground.

Imagine pushing a car opening and holding its door only. If you push the car holding the edge of the door, the door is likely to be damaged instead of moving the car. If you hold a closer to the door hinge, the door wont get damaged or bent. Same case here.

[searchingheaven]

Originally Posted by audioholic

Since bigger aircraft need more force to roll around, the ailerons alone will be stressed if the commanded roll is more. And since the ailerons sit at the edge of the wing, it will also put a lot of stress towards the edge of the wing. Hence, since these aircraft are big, they have the flaperon which aids in providing roll and also act as spoilers once the aircraft is on the ground.

Originally Posted by norhog

I say this because at take off it is sitting lower like flaps. In flight it moves very rapidly up and down as if it is trying to maintain some flying condition. And on landing it is lifted up like a speed brake.
May be I am mistaking some terminology here. So this part (part x) sits between the flap and aileron and is controlled somehow to move very fast up and down during the flight, like a flap during takeoff roll, spoiler/ speed brake on landing.

So airplanes engines having power outputs close to these vessels need to comply with emission regulations.?

Sorry for misunderstanding your question the first time. Yes, the part you're referring to is known as a flaperon. It is unique to the 777 and the 787.

The flaperons and ailerons provide roll control, assisted by asymmetric spoilers. The flaperons are located between the inboard and outboard flaps on both wings. In the normal mode, they are used for roll control. For increased lift, the flaperons move down and aft in proportion to trailing edge flap extension. In the normal mode, the ailerons and spoilers 5 to 10 are locked out during high–speed flight; the flaperons and remaining spoilers provide sufficient roll control. During low speed flight, ailerons and spoilers 5-10 augment roll control.

A schematic of the 777's flight control surfaces on the wing.


Emission Standards

All aviation emission sources are regulated through equipment specific regulations, standards and recommended practices, and operational guidelines, which are established by a variety of organizations like ICAO, EPA etc. And FAA certification is required for essentially all aviation equipment and processes. There are more than 60 standards that apply to aircraft engine design, materials of construction, durability, instrumentation and control, and safety, among others. These are in addition to the Fuel Venting and Exhaust Emission Requirements for Turbine Engine Powered Airplanes (FAR Part 34), which guide compliance with EPA’s aircraft exhaust emission standards. ICAO does all it can to reduce emissions and set better standards. But with aircrafts, there is one variable which comes before anything else – safety. So unproven and untested technologies are not implemented – even if they provide a lot of benefit in terms of reducing emissions.

[norhog]

Audioholic and Searchingheaven thank you very much for the answer to my questions.
This thread is fantastic because if gentlemen like your good selves.

[norhog]

Well this one is not related to 777 in particular but to aviation in general.
1. How does a fighter aircraft fly upside down. Considering the wings have a airfoil cross section creating high air speed on top which in term created a low pressure area. So I am guessing the elevators are adjusted or something. Grateful if you could explain something in this regard.
2. Could a commercial aircraft do it. Had read somewhere the stresses induced would break the aircraft. Is it possible?

[hangover]

Great thread. A few questions from a landlubber.

1. In the first picture you show the different screens in the cabin. On the right bottom is a small 1 feet table called as maintenance table or something. What can you repair on it?
2. You have cameras showing the outside. Don't you need views of the cabin interior?
3. I know 777-200/300 LR/ER is long range and extended range. What do the 200 and 300 represent?
4. Why can't the bottom of the cockpit be a transparent glass of suitable material? That way you can line up the nose exactly.
5. ILS is instrument landing system. Is there something like a ITOS - instrument take off system?
6. I've seen pilots use a static based film that is placed on the windshield by pilots. They move it depending on the sun position. Can I use the same in my car? Airspruce sells them.
7. I read that an A320 can't dump fuel. Whereas a 737 can. So in an emergency the Airbus has to keep on circling till the fuel is empty. Is this a characteristic on all Airbus?

[searchingheaven]

Originally Posted by hangover

1. In the first picture you show the different screens in the cabin. On the right bottom is a small 1 feet table called as maintenance table or something. What can you repair on it?
2. You have cameras showing the outside. Don't you need views of the cabin interior?
3. I know 777-200/300 LR/ER is long range and extended range. What do the 200 and 300 represent?
4. Why can't the bottom of the cockpit be a transparent glass of suitable material? That way you can line up the nose exactly.
5. ILS is instrument landing system. Is there something like a ITOS - instrument take off system?
6. I've seen pilots use a static based film that is placed on the windshield by pilots. They move it depending on the sun position. Can I use the same in my car? Airspruce sells them.
7. I read that an A320 can't dump fuel. Whereas a 737 can. So in an emergency the Airbus has to keep on circling till the fuel is empty. Is this a characteristic on all Airbus?

1. That is not exactly a table. It is a small compartment where we keep our QRH, FCTM and other manuals. Although I will say that it is not named accurately. Actual maintenance or troubleshooting is done from the upper overhead panel, where there are a lot of circuit breakers installed for different systems.
   
   Picture showing the maintenance table and the windows shades.
   
   
2. Under the new CRM(Crew Resource Management) guidelines, pilots do not have to be occupied with anything outside the cockpit. Any emergency in the cabin can & will be handled by the flight attendants. Besides, I can't think of any reason for needing it.
   
   
3. Just a variant designator. No references to any parameters.
   
   
4. First off, as I said earlier, taxiing using the camera is just an added luxury. If we want to taxi without the GMCS, we can easily do it. And secondly, using a glass floor is simply not an option. A lot of mechanical constraints will be present.
   
   
5. No, there is no such Instrument Take Off System. But, commercial jets fly IFR, or instrument flight rules.
   
   
6. Yes, we use sun shields or retractable sun films in the cabin to cut out the glare. As far using it in a car is concerned, I am afraid I cannot help you much. Other members would probably know about this.
   
   
7. No, a 737 cannot dump fuel at all. Fuel dump is only required for aircrafts that cannot reach their MAP(Missed approach performance) after 15 mins of flying.

Originally Posted by norhog

Well this one is not related to 777 in particular but to aviation in general.
1. How does a fighter aircraft fly upside down. Considering the wings have a airfoil cross section creating high air speed on top which in term created a low pressure area. So I am guessing the elevators are adjusted or something. Grateful if you could explain something in this regard.
2. Could a commercial aircraft do it. Had read somewhere the stresses induced would break the aircraft. Is it possible?

Whether flying normally or inverted, the principles of flight remain the same. The wing deflects air downwards. When inverted, the pilot simply controls the pitch of the aircraft to keep the nose up, thus giving the wings sufficient angle of attack to deflect air downwards. So theoretically, any aircraft can fly inverted. The controls are reversed, i.e. to pitch up wrt ground, you push down on the yoke and vice versa.

Now there are two parts to this. If by inverted you mean doing a couple of barrel rolls and then straightening out, then this has been done in commercial jets such as the 707 and 747. But if you mean inverted flight for an extended amount of time, then that is not possible in jets due to the fuel lines. Fuel lines typically draw fuel from the bottom of the tank. Therefore, in inverted flight, the engines will die due to fuel starvation. Same goes for the oil system.

[Thad E Ginathom]

I came across this thread a couple of weeks ago, and then forgot it until today. There were quite a few pages to catch up, but, like a gripping book, I could not "put it down" until the end. Now I'm subscribed, so won't miss it day by day.

Many thanks to you and to the other pilot/informed contributors and to the less-informed for asking such great questions!

[prashanthyr]

Awesome thread on one of my favourite topics !

I havent been able to go through the entire thread yet, so please forgive me if this question has already been asked -

I have always been curious about crew rest areas - can you please throw some light on that?

thanks

[Thad E Ginathom]

Originally Posted by prashanthyr

I have always been curious about crew rest areas ... ... ...

I can't even say what plane it was (BA, London/Chennai, July 2015), but the door at the back, with the steep stairs behind it, through which cabin crew occasionally disappeared and reappeared, really intrigued me. I googled, and found pics of their hide-away nests on various aircraft --- and that flight crew have their own, separate arrangements.

[Jeroen]

Originally Posted by norhog

Well this one is not related to 777 in particular but to aviation in general.
1. How does a fighter aircraft fly upside down. Considering the wings have a airfoil cross section creating high air speed on top which in term created a low pressure area. So I am guessing the elevators are adjusted or something. Grateful if you could explain something in this regard.
2. Could a commercial aircraft do it. Had read somewhere the stresses induced would break the aircraft. Is it possible?

Here is the very famous footage of the 707 rolling. Listen to the audio! The management was not impressed and told him not do it again.

http://youtu.be/-KNbKFMBsQE

[hangover]

Originally Posted by Jeroen

Here is the very famous footage of the 707 rolling. Listen to the audio! The management was not impressed and told him not do it again.

I don't think a plane will break by doing a barrel roll. Planes are extremely strong.

It's possible there was very little fuel in it. Probably fumes. Only then can it roll over.

A plane on a commercial flight will have the inertia of a full tank of fuel.

That's the same reason formula 1 cars do this fuel trick. When they need extremely fast lap times, they put less fuel in the tanks.

I've always wondered why airlines don't use simple technology to save money.

Take your typical LCC. Air hostesses go along the aisles selling food and drink and collecting money.

Why not fix a touchpad on each seat? The buttons will have stickers of the available food. A passenger simply keys in a few buttons and a console in the hostess area will indicate who wants what.

A level further. Everyone pays for tickets by some sort of card. So collect an extra Rs. 500/- and refund unused money at the end of each flight back to the cardholder.

Like frequent flyer miles, we can have exquisite eater miles.

If a passenger does not eat anything refund Rs. 510/- as his seat will have 0 debris to clean. This can count towards the elegant flyer miles.

[honeybee]

Originally Posted by hangover

I've always wondered why airlines don't use simple technology to save money.

Take your typical LCC. Air hostesses go along the aisles selling food and drink and collecting money.

Why not fix a touchpad on each seat? The buttons will have stickers of the available food. A passenger simply keys in a few buttons and a console in the hostess area will indicate who wants what.

Installing the touchpads and the related systems will push up the cost of the plane, not to forget maintenance, breakages and complaints from passengers that touch pads don't work. Air hostesses do it without any extra charge.

Originally Posted by hangover

So collect an extra Rs. 500/- and refund unused money at the end of each flight back to the cardholder.

Like frequent flyer miles, we can have exquisite eater miles.

If a passenger does not eat anything refund Rs. 510/- as his seat will have 0 debris to clean. This can count towards the elegant flyer miles.

I don't think people will pay a 'refundable' deposit for an airline meal. Not sure if regulators would allow it. And not sure if it will save cost for the airline to process refunds for those who did not eat.it. And not sure if it will save cost for the airline to process refunds for those who did not eat.

Also seat cleaning will always be required as it is not just food alone that needs to be cleaned up. Body odours, perspiration, germs all exist without food. Plus people bring something to eat with themselves.