BeechTalk - BT - FAA Grounds Citation 525s With Tamarack Winglets

Username Protected · **Posted:** 18 Jun 2019, 21:40

The winglets benefits are the largest on underpowered airframes - CJ/CJ1. Cessnas current production CJs - M2 & CJ3+ - have well matched airframes and engines, can clinb directly to max altitude, and can hit MMO at their max altitudes. My understanding is Cessna has looked at winglets and concluded they are not worth the effort.

The M2 has small winglets that I have heard are mostly for show.

Username Protected · **Posted:** 18 Jun 2019, 22:25

Username Protected wrote:

Mike you really are a glass half full sort of guy aren’t you?

Unless we are talking about the MU2.

Username Protected · **Posted:** 18 Jun 2019, 23:46

Username Protected wrote:

What is the weight difference between the active winglet system and control surfaces vs the structure needed for the wing to have normal winglets installed.

Probably a wash given the system is 81 lbs. That's a lot of structure you can add.

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How much of the benefit is the winglet or just the longer span wing?

Extension is more beneficial per unit length than winglet.

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Could it be almost as good with a tip extension and no winglet?

Probably.

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I would imagine it would be only available as an improvement to a new airplane and not a retrofit kit for older airplanes.

For a passive winglet, yes, the structural changes are extensive and invasive.

Mike C.

Username Protected · **Posted:** 18 Jun 2019, 23:48

Username Protected wrote:

Mike you really are a glass half full sort of guy aren’t you?

I have a low opinion of companies that make false claims.

Mike C.

Username Protected · **Posted:** 19 Jun 2019, 07:26

Username Protected wrote:

Extension is more beneficial per unit length than winglet.

What does actually mean?

If that was true (assuming I think what you may mean) why doesn’t Boeing and/or Airbus just extend the wing of a 737/A320 for example.

Good basic summary of winglets. https://www.nasa.gov/centers/dryden/pdf ... 5-DFRC.pdf

Andrew

Username Protected · **Posted:** 19 Jun 2019, 08:36

Username Protected wrote:

What does actually mean?

A foot of wing span is more effective than a foot of winglet height.

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If that was true (assuming I think what you may mean) why doesn’t Boeing and/or Airbus just extend the wing of a 737/A320 for example.

Longer wing span causes problems packing planes at gates.

Winglets have a certain "modern" look to them, similar to tail fins on cars in the 1950s. There is a style component to having them, a sign of apparent sophistication.

Mike C.

Username Protected · **Posted:** 19 Jun 2019, 11:04

Username Protected wrote:

What does actually mean?

A foot of wing span is more effective than a foot of winglet height.

Quote:

If that was true (assuming I think what you may mean) why doesn’t Boeing and/or Airbus just extend the wing of a 737/A320 for example.

Longer wing span causes problems packing planes at gates.

Winglets have a certain "modern" look to them, similar to tail fins on cars in the 1950s. There is a style component to having them, a sign of apparent sophistication.

Mike C.

Username Protected · **Posted:** 19 Jun 2019, 11:43

The NASA link that Andrew posted is a good primer.

Winglets can work a couple different ways:

They can work a lot like extending the wingspan, which inhibits wingtip vortices, which always means less induced drag at some given airspeed and weight. It's sorta like adding another foot of metal pointed either straight out or straight up. Both will get in the way of the wingtip vortices (there will still be a wingtip vortex, just a bit weaker) and both reduce induced drag by approximately the same. Both ways need a stronger wing too.

They can also provide a small forward force- the air wants to spill out from underneath the wing and around the wingtip, and the relative wind against the winglet can make a lift vector that points slightly forward. That winglet's lift vector is pointed mostly inward though and it is a considerable force on the structure of the wing, which again means the wing needs to be built stronger and heavier.

(The "sharklet" winglets are another case and work a little bit differently still.)

As the paper mentions, there is a lot of detail design and testing to get them just right.

Exactly what all the different lift and drag vectors are doing is interesting but it's kinda beside the point when you're paying for the gas... the bottom line is what matters.

Username Protected · **Posted:** 19 Jun 2019, 17:35

Username Protected wrote:

They can also provide a small forward force- the air wants to spill out from underneath the wing and around the wingtip, and the relative wind against the winglet can make a lift vector that points slightly forward.

Yes, but this use case is very tricky to get right since it varies with CG, weight (AoA), airspeed, and altitude. The basic idea is to convert the wing tip vortex energy to some forward thrust by adjusting the angle of the winglet fin. For any given flight condition, there is one optimal angle, and it varies as conditions change.

Mike C.

Username Protected · **Posted:** 19 Jun 2019, 22:11

Username Protected wrote:

They can also provide a small forward force- the air wants to spill out from underneath the wing and around the wingtip, and the relative wind against the winglet can make a lift vector that points slightly forward.

Yes, but this use case is very tricky to get right since it varies with CG, weight (AoA), airspeed, and altitude. The basic idea is to convert the wing tip vortex energy to some forward thrust by adjusting the angle of the winglet fin. For any given flight condition, there is one optimal angle, and it varies as conditions change.

Mike C.

Username Protected · **Posted:** 19 Jun 2019, 22:16

Username Protected wrote:

Sounds like a need for a movable winglet to account for that.

Username Protected · **Posted:** 19 Jun 2019, 23:04

Appears airbus thinks the idea would work on big planes.
https://www.flyingmag.com/airbus-test-f ... p-concept/

Maybe they will figure out how to avoid the failure modes.

Username Protected · **Posted:** 20 Jun 2019, 03:49

Username Protected wrote:

The basic idea is to convert the wing tip vortex energy to some forward thrust by adjusting the angle of the winglet fin. For any given flight condition, there is one optimal angle, and it varies as conditions change.

Easy, just make it adjustable too.

https://www.wingsmagazine.com/tamarack- ... ets-15135/

[youtube]https://youtu.be/cyPDS1LCgBE[/youtube]

Andrew

Username Protected · **Posted:** 20 Jun 2019, 07:31

Username Protected wrote:

The NASA link that Andrew posted is a good primer.

Ok let’s get serious

https://commons.erau.edu/cgi/viewconten ... ontext=edt

Andrew

Username Protected · **Posted:** 21 Jun 2019, 10:16

There has been some chatter that is being shared by Tamarack on CJP regarding their status. According to them - they have completed all of the flight and engineering tests conducted by EASA and the EASA engineers are satisfied. They now will have to conduct meetings to analyze all the reports and make a ruling.

Full disclaimer, this data is coming from Tamarack, so recognize the bias. I am hopeful that this is true and a decision is quick in coming. I suspect we are still weeks away, but maybe I am wrong.

-Jason