The Cheetah is a light, single engine airplane and wake turbulence can put some pretty big hurt on these aircraft. But lest anyone think they're safe in a larger aircraft, I was on ATR-42 on final into IAH in calm air when CO was flying them a few years ago. About 5 miles out around 2000 ft., we felt a slight bump followed seconds later by another slight bump, followed by an immediate gut-wrenching left 60% bank. (normal turns are usually 30% or less for comfort of passengers.) Needless to say there were some screams in the cabin but the pilot maintained control and we landed without incident.

The AA Airbus out of JFK a few months after 9/11 was also a wake turbulence encounter.

Happy flying :D

.....

Not looking to argue either, but the Aviation Partners Boeing advertisments on the back of Airways Magazine said "about 10% fuel savings" - then again thats marketing taking - getting even a 5% savings is good.

-Vincent

The significant percentage savings are only attained while at cruising levels and speeds. In the climb and descent the winglet has a negative effect. In addition it is extra weight which, as gross weight stays the same, has to be taken from fuel or payload if required.

On the Boeing 747-400 winglets were standard, except on the ones used by Japan Air Lines and All Nippon on domestic flights within Japan where calculation showed they had a negative net effect.

The winglets are not necessary for flight and if damaged on the ground (and of course they tend to get hit first) can be removed for flight, there is a standard procedure for this.

Anyone looking for inspiration for them has to go back further than Rutan. Eagles and similar birds have been doing this for a lot longer, with those tip feathers they spread out while cruising along. The reason they do this is exactly the same.

So going back to my OQ in the OP, are we to assume that the (apparently) bigger winglets on the 73s and 75s are the result of aircraft designers/manufacturers finding that they (bigger winglets) are even better than the earlier, smaller versions?

I'm no AE, but it's not that simple. Geometry of the wing, weight of the aircraft, average flight distance and cruising altitude... they all play a role in the size and geometry of winglets. As an earlier poster said, larger winglets may further reduce the wake vortices and thus induced drag, but create more drag due to their size.

It's purely anecdotal, but I've also noticed that near-vertical winglets seem to be taller. If you look at 744/A340/A330 winglets, they are nowhere near vertical (maybe 45-degrees) but the 737/757/Learjet winglets are nearly vertical and much taller. The MD-11s are somewhere in between.

Article on winglets in the Lufthansa in flight magazine a few months ago. The % they save in fuel is low single digit. The investment to fit them is very high and when the world oil price is low the savings may not match the capital expenditure. Of course with oil prices as they are you will see more and more of them.

CO's statement says 5%. At 40 million barrels a year, this would be a substantial savings that would be recouped eventually. I've heard that they cost about 2 million an AC.

Beyond the ever important potential fuel savings I think the winglets are a great option for the related increase in range. Suddenly this opens up a lot of new destinations in Europe without a significant expenditure on new equipment.

Winglet envy?

...(music).."Up side down, you're turning me.."
 

The Rutan brothers are brilliant pioneers.

"Rutan was the innovator of controlling wingtip vortices and converting that wasted force into lift. Not much of a tip vortex on a paper plane. ;)

BTW, the tip vortex is from high pressure air under the wing spilling out toward the top of the wing, not vice versa. "

True

"I flew into a tip vortex coming from a C-130 while on final approach to Huntsville AL. It flipped my Cheetah completely inverted in a right roll in less than a second but I instinctively added full right aileron to complete the roll and landed uneventfully. Took 10 minutes to get my underwear out of my tush.[/QUOTE]"

Inverted on final is NOT my favorite position. I think I would have instinctively fought it with Left aileron. Are you aerobatically trained?


...(music).."Up side down, you're turning me.."

I thought that's what I wrote :)
In any event, I have also flown a Piper Navajo twin across vortices widthwise, which was like hitting a giant speedbump doing 50. It wasn't too pleasant.

Any design that can reduce their effect and improve safety while improving fuel efficiency is a winner in my book. Not to mention they are cool looking too.

Not to be a party-pooper but I can't see 5% range increase opening up a lot of destinations that wouldn't have otherwise been accessible, but I'm sure there's a couple that might open up.

Aerobatically trained?
 

I can only wish, Bernoulli. My CFI was a maniac on unusual attitudes and had me under the hood from my second lesson. His mantra was to cope with the forces, not fight 'em. It paid off several times. but this event was the most notable.