That's BS.

Winglets do not increase the range of an airplane by 35%.

They don't increase cruise speed by 35%, they don't reduce fuel flow by 35%, or any combination of the two that results in 35% more range.

Mike C.

That's BS.

Winglets do not increase the range of an airplane by 35%.

They don't increase cruise speed by 35%, they don't reduce fuel flow by 35%, or any combination of the two that results in 35% more range.

Mike C.

I would not read more into Cessna's deal with Tamarack then that Cessna wants to make the money on the installs. I don't believe it says anything about the benefits or the performance claims. It does say that Cessna is willing to support the mod in their Service Centers.

It is no lose to Cessna. If the market rejects this mod they lose little. If owners buy the mod for the sex appeal or claimed benefits Cessna drives customers and revenue into the Service Center. And I will bet that any plane that comes in for that mod will have other work done delivering incremental revenue.

Cessna needs to drive business into their Citation Service Centers. This is an economic deal. Cessna also locked out other shops from doing installs at lower cost.

I would not read more into Cessna's deal with Tamarack then that Cessna wants to make the money on the installs. I don't believe it says anything about the benefits or the performance claims. It does say that Cessna is willing to support the mod in their Service Centers.

It is no lose to Cessna. If the market rejects this mod they lose little. If owners buy the mod for the sex appeal or claimed benefits Cessna drives customers and revenue into the Service Center. And I will bet that any plane that comes in for that mod will have other work done delivering incremental revenue.

Cessna needs to drive business into their Citation Service Centers. This is an economic deal. Cessna also locked out other shops from doing installs at lower cost.

$300K for winglets? Am I reading that right? Wow.

Their solution is more than some bolt on wing tips. It includes active flight controls and electronics.

It is still pricey but I am sure their certification was not cheap.

The performance enhancement is amazing.

Look like it...but won't help you much VFR at 17,500'

Glenn

Alex did:

Max range for the CJ is just over 1300 nm in the best of cases... by yourself. With the winglets, TAG has been getting north of 1750 nm with max range settings.

That's a 35% increase. That's what I questioned.


That's believable.


Understood, but most of that time savings is in the last bit of climb where you are already at fairly low fuel flows. It isn't, as one might superficially assume, providing twice the climb rate over most of the climb profile. The little bit extra effective wing area from a winglet provides the lower induced drag at high altitude to make the climb rate at TOC better.


Winglets eat into the design margin of the wing structure. That's a given. They function by moving the center of lift further outboard, essentially making the wing tip area generate more lift, thus lowering the effective wing loading. If you don't change the structure, but move the center of lift out board, the wing is less strong. That's inescapable. Now there may be enough margin in the wing to still meet FAR 23 requirements, but you can't put winglets on a wing and not change the point at which the wing will break.

That is why adding winglets often reduces Va, for example.


Winglets have a good PR machine behind them. They have benefits, but not nearly to the extent claimed in much of the sales literature.


That flight is too old for me to get data on it from Flightaware, so I can't verify they were honest in the presentation. If I had date and time, I could look up soundings and verify the claimed 26 knots tailwind figure. The article is dates June 6, 2013, a Thursday, maybe this was June 4, 2013 from the sound of the AIN report saying "Tuesday night"? I'll look that date up and see what the winds aloft actually were.

Even so, 1859 nm distance minus the 163 nm tailwind benefit is 1,696 nm and to land with 70 gallons of fuel in a CJ is very marginal, clearly not enough for the NBAA IFR range protocol with a 100 nm alternate. So we may be comparing apples to oranges here.

Mike C.

That's where Tamaracks active flight controls come in to reduce the wing loading. Thus the additional cost over passive winglets.

If their claims are correct then there will be no penalty. Apparently the FAA and Cessna has bought into their engineering and flight test data on the wing loading.

If they are wrong then there will be and AD in a few years.

The performance enhancement is amazing.

Whatever Mike... I'll ask Tamarack to contact you when they are finished with EASA and the FAA so you can also certify their claims.

1,696 nm - with your adjustments - marginal or not is not doable in a straight CJ under any circumstances. You would flame out 300 nm before reaching this point.

Those come into play only during high loads. Their system is basically a lift dump when G loads exceed a certain level. This is useful to keep the ultimate load on the wing less.

How do you know the lift dump works? What happens if it isn't? What power does it depend on? What do you do if that power fails? What do you do if it activates when it should not?

This is borderline fly by wire. A computer is moving control surfaces.

If they get this approved by the FAA, why not equip all airplanes with these lift dump devices and then we can make weaker, lighter wings.

Also, during normal flight, the wing spar IS under more stress as the winglets DO move the center of lift outward. If the winglets did not do that, they would not have any aerodynamic benefits.


Very small increases in wing stress have radical reductions in wing fatigue life.

Mike C.

Below is from the Cessna CJ1 Flight Planning Guide. Difference between the CJ and CJ1 is largely in the avionics and performance is similar.

Get to FL410 30 minutes quicker and cut into the fuel reserve and it looks like you can get 300 - 400 nm more range. Buyers have to ask themselves how often they can safely fly that profile.

You choose not to quote my next statement which was "If they are wrong then there will be and AD in a few years." So I think we agree that there are unknown risks in this design. Buyers need to consider who will pay for any AD repairs since it is likely that Tamarack does not have deep pockets for that.