winglets - do they work...
 

Do winglets work? The age-old question in aviation that no one can seem to answer. I see that Boeing are now offering winglets to retrofit to the 737-300, yet they produce the 777, the longest-ranging aircraft on earth, without them!

Go figure...

The 777 ER has raked wingtips, which has similar effect.


K

.. winglets work fine .. but not as well as what they stand in for .. extra span. Problem is airport infrastructure.

Well they look real nice anyway..:}

if you understood how wake turbulance is produced and how this causes excess drag, the winglets are there to prevent some of the wake turbulance and gain some extra fuel economy. Not noticable on short haul, but long haul definatly.

The basic principle is because of lift, which is high pressure on the underside of the wing and low pressure on the top of the wing, the air naturally wants to flow to the top of the wing where the low pressure is. As it tries to do this it overlaps the outer edge of the wing causing it to spiral as the wing continues on the flight path.

To maintain level flight and level speed, thrust must equal drag, so more thrust (fuel) is required to compensate for more drag. With the winglets the theory is you will need less thrust to maintain the same speed because you have less drag. Although the cost of retrofitting and certification sometimes is more than the savings that will be recovered, which is why it is more viable on the long haul fleets

I believe the Winglets still are a option on most A/C aswell, so the carriers decide if its viable for the winglets for the route they are purchasing the A/C to fly.

Look at most of JAL 743's and 4's, alot of them are shorthaul only


Hope this helps

4s

4spooled

As Kanga and JT said, winglets are only useful if you can't add extra length to the wings. The raked wingtips that Boeing developed for the B767-400 are a superior solution to winglets as they produce lift at the same time as reducing wingtip vortice drag. This is why Boeing is fitting them to the B773ER and B772LR. :ok:

Going Boeing,

Adding extra wing span will increase the loads at the wing root, the overall aerodynamic compromise is not as simple as adding some more wing or a winglet.

Either way, it will require some form of structural modification to the wing.

The best looking ones I have seen are on the Continental Airlines 757-200..some 8 foot 2 inch tall...with a block fuel reduction of up to 5%.

:ok:

Additional to the above, the 737-300 wing was designed decades before the 777 wing and the efficiency advantages of the newer creation are significant - Winglets, vortex generators, etc, are not as necessary these days due to modern wing technology improvements.

Span restrictions due to airport infrastructure are few and far between given most airports/aerobridges/tarmac areas easily cater for 707s, A320s, etc, etc also. I think that's what you meant??

Adding a winglet to an old design is a relatively cheap measure to lengthen the relevance of an old design, just like hush-kitting or re-engining. Also helps puts off the possibility of the operator (customer) buying a new machine from a competitor.

Whether the aerodynamic advantage greatly outweighs the physical weight penalty of the winglet, itself, on short-haul ops is for the bean-counters to wet themselves over, I sure wouldn't know.


As for looks, personally I believe having winglets of any shape or size, particularly the Airbus style, "spoils the look of the thing", as 'Moggy' Cattermaul once said.

Raked tips are definitely shnazzier.

While I'm at it, jet engines should always be at the back... :ok:

Why the hell is this thread in D&G Reporting Points? There are far too many facts for this forum!

SWH,
Same goes for winglets, when 737 NGs are retrofitted with winlets there are some strutural mods done down the wing due to increased bending moments. Biggest decision is cost of mod v fuel savings v length of time depreciated.
NG winglets work , 744 winglets are close to a waste of time.

Tank Engine,

Doesn't the 744 only have winglets so people can tell that it's a nice shiny new 747 instead of a crappy old 743?

And is it true that you can operate with one off? That'd cause a stir amoungst the journos...

Capn Bloggs

The 330 can operate without one but with a extra burn to account for - see the 330 that sawed off a Dash 8's tail at YVR recently.

CO are pushing the 757 as a east coast US to British Isles/Western Europe option, thus the wingleting. Icelandair are also doing it (since Iceland to pretty much anywhere is medium haul at least) and apparently AA are looking at it too, as they also have 757s they can replace on SH on with 738s.

Capt Bloggs,
Thats about right, from memory [I don't have a 744 DDG with me] you can operate with one or none with no performance penalty!!:ooh:
I have heard that Boeing considered not continuing with them but airlines now wanted them for the purpose you said!;)

Tankengine & Capn Bloggs

That’s funny because Our MEL/CDL for the B744 states:

This does belong in Questions

I read a letter in Flyer magazine about winglets here is what it said, it is written in relation to GA aircraft but i think same concept of winglets is used on Jets.

Question: "Nowadays one sees more and more aircraft fitted with winglets. Some are small but others are several feet long. What aerodynamic effect do these winglets have?

Answer:
"The winglets fitted to aircraft have two functions. Their primary purpose is to reduce drag. There is lower pressure on the upper surface of the wing than there is on the underside - and as a result there is some span-wise flow towards outwards on the underside of the wing and inwards on the upper surface. When these two airflows meet they produce a vortex off the trailing edges and this is greatest at the wingtip: the air curls up from the underside producing a large vortex at the tip. This energy is all wasted, as it is almost all drag. Adding the winglets straightens out the airflow to a considerable degree and so reduces the aerodynamic drag a worthwhile amount in particular conditions - usually at cruise speeds. Some aircraft are fitted with fuel tanks at the tip, which have a very similar effect. In additional to the reduction of drag the winglets also produce a stabilising force in roll and so make the aircraft easier and more comfortable to fly - which is why some of them are so large."

backs up my views on them anyway.....

4s

In addition to (or probably in the act of) reducing the tip vortices and so reducing induced drag that way, I remember reading somewhere that on some types the winglets are set at an angle to the aircraft centreline (in the yawing plane), and that this allows some thrust to be generated because of the angle at which the tip airflow strikes them - kind of like the sail on a boat.
Any aerodynamicists able to confirm or deny this?

Yeah I have heard that is true. Apparently the MD-80 winglets are optimised to produce thrust, rather than reducing induced drag or increasing effective span.

I saw some bloke in a souped up Nissan the other day with what appeared to be winglets on his rear spoiler. Big ones too.

Looked rediculous.......:yuk:

I’ve heard the term thrust used as well and it is the wrong term guys. All they are doing is producing a component of lift in the horizontal plane that assists thrust. They DON’T, repeat DON’T produce thrust.