Jump to content

lower winglets....


cncdoc

Recommended Posts

has anyone noticed that many pictures of Cozys don't show the lower winglets?

Look at Brocks page. It shows a Cozy with no lower winglets.

Personally, I like the looks sans winglet. But with the vertical stabilizer as big as it is, is the winglet necessary? If it is to add lift to the main lifting body at the tip like a flow fence, wouldn't the shape be different?

 

I know, I know. It's in the plans. But so is Nat's admonition to use the manual nose gear retraction. Yet how many opt for the JW electric? HA! I got ya there!

 

So, where is the love for the lower winglet here?

 

:confused:

Brock's page pic with no lower winglet

Back to building... #618 Cozy MK IV

 

My Cozy web pages, courtesy: Rick Maddy... :cool: WN9G :rolleyes:

Link to comment
Share on other sites

As I understand it, the lower winglets are critical to help stop main wing stall, or deep stall. Nat did a number of tests and even had a test pilot test his Cozy with an adjustable sliding lead weight to change his CG. He found that he needed to shorten the canard and add the winglets to the make the Cozy stable for the published CG limits.

 

There are probably a number of Cozys that have not made the canard or winglet change.

 

Somebody please correct me if I am wrong.

Mike LaFLeur - Cozy MkIV #1155
N68ML
76225.gif

Link to comment
Share on other sites

Originally posted by cncdoc

Personally, I like the looks sans winglet....

You're in good company here. I've never met anyone who didn't think it looked better without winglets.

 

<... If it is to add lift to the main lifting body at the tip like a flow fence, wouldn't the shape be different? ...>

Actually, it inhibits spanwise flow. Spanwise flow will degrade low speed performance, particularly roll authority. It also affects cruise performance, but to a lesser extent.

 

If you are ever nearby (like less than 100') when a canard touches down - particularly if he is slow - you will note that the wing tips are only a foot or so off the ground. It doesn't take much of a gust or bounce to drag a wing tip. I will retain my plans lower winglets for skags. I'd rather scrape up the bottom of a winglet than rip a rudder off.

 

<... So, where is the love for the lower winglet here? ...>

Don't know. It may be unstylish, unsightly, whatever, but I'll have to keep mine for practical reasons.

...Destiny's Plaything...

Link to comment
Share on other sites

My only question is why the aerodynamically "poopy" looking design (no offense intended)?

 

It would seem that a more STOL style tip would be effective in converting spanwise flow (like the tips on the canard only inverted). It wouldn't have to be as aggressive as a STOL design, but I would think that it would be a better airfoil than the skeg protrusion that it calls for.

 

That's just MHO however. If it's simple and it works, then fine. The rather elegant shape of the wing is going to end up being assailed with vortilons and flow fences anyway - in the name of low speed manueverability. So, aesthetically speaking, it's already on it's way toward the porcelain convenience. I was trying to save as much as possible from geekdom.

 

Thanks once again...

Back to building... #618 Cozy MK IV

 

My Cozy web pages, courtesy: Rick Maddy... :cool: WN9G :rolleyes:

Link to comment
Share on other sites

Originally posted by cncdoc

My only question is why the aerodynamically "poopy" looking design (no offense intended)?

You'll have to take that up with Burt. He's not into poopy looking stuff, and he designed these protrusions. Wing tip performance enhnacers are a black art. I just do what they (Burt et al) tell me. You might be able to get away with a much lower piece at the leading edge and have it droop down lower to the trailing edge (particularly if you have fences at both ends of the ailerons and perhaps on the cowl.) Like draw a line from an inch or so below the wing at the LE to the "break" in the bottom toward the TE and make it thinner.

 

Whatever else I do, I'll retain a skag.

...Destiny's Plaything...

Link to comment
Share on other sites

I agree w/CNC regarding the look of the winglets, although I don't know what poopy means exactly. :confused:

 

I am definitely going to have winglets on my plane for the stall issues, but may make a minor change. The plan winglets have an angle in them. Why is that necessary? I suspect it would be more aerodynamic and aesthetic in a slightly different form. Minimally, I'm going to sand the angle out of my shape.

 

An inverted canard tip is also interesting, and why we're at it, how about putting the rudders closer to the fuselage? :scared: This would require larger rudders, assuming the current rudders are as small as they can/should be.

 

Posted Image

More info here.

 

But that's a bit more than sanding the bend out of the plan form, and would, of course, require a complete aerodynamic analysis on the NEW plane that would evolve.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

Link to comment
Share on other sites

My opinion of the lower winglet appearance was not the poopy part. It was that the design seems to not be optimized for it's function (That, as indicated above, it seems, was for low speed lift enhancement) that's all. I always thought the straight down skeg design was to give stabilty during yaw manuevers.

 

It's obvious that the rudders have to be where they are because it would be a major pain to re-engineer the whole wing again and figure what to do with the ailerons.

 

That picture of the Firefly didn't show a turned down wing tip either.

 

Maybe in keeping with Burt's KISS method, the winglet is just enough to function, any less and it wouldn't work, any more and it wouldn't be Burt.

 

I'm not Burt though:p

Back to building... #618 Cozy MK IV

 

My Cozy web pages, courtesy: Rick Maddy... :cool: WN9G :rolleyes:

Link to comment
Share on other sites

Have you guys read all the Canard Pusher, CSA, and Cozy news letters? If not it would be in your best intrest to do so. A lot of the questions posted here would be answered. Also if you had read Tom Staggs artical on trailing edge fences (lots of pics, and data) on his Long-EZ "same wing as a Cozy" you would have found out they work good on Variez wings but have little effect on Long-EZ wings. The lower winglets are worth putting on to protect the wings from getting damaged by hi insedent landings, cross wind tip. And when your empty plane tips over backward because of inexperianced help. Please don't jump all over me. I just want to help. :thumbsup:

If the phone don't ring. It's me

Link to comment
Share on other sites

So the winglets aren't really aerodynamically necessary?

 

They are more of a sacrificial "ski" in the event of a landing boo-boo. Maybe I should put a wheel in it :eek: ??

 

I have read some of those forums.

 

At first, I was impressed at how much the information appeared to sound useful and accurate. But, the more I read, the more I could see that a lot of it was opinion based on others' opinion and data taken from 50 year old technology and blanket conclusions from others' mistakes.

 

For instance: You say you wish to do something not in the plans. They say don't do that because something won't work right if you do. You say you want to anyway, then the local expert chimes in and castigates you and makes you look like a retard for even thinking about the intended "deviation from plans".

 

That having been said, I have found them useful for obtaing materials and interpolating and extrapolating flight and performance data from those who fly and those who are modifying their aircraft.

The flow fences I intend to use (although not in the plans). There are other changes I may make as well, but I want to get it done so I can fly it. I may make another one and make it fancy, I bet I could do it in half the time.

 

But thanks Chuck, I appreciate your input. You always make sense.:cool:

Back to building... #618 Cozy MK IV

 

My Cozy web pages, courtesy: Rick Maddy... :cool: WN9G :rolleyes:

Link to comment
Share on other sites

I think I remember Burt explaining the lower winglets prevent the drage off the end of the wings that goes with angled wings. As for the upper winglets. They are for stability. Way back when. The prototype Longez had no rudders on the winglets. It used a front mounted rudder under the rudder pedels up front. it was replaced early on with little rudders on the winglets about 8"X 8". After that the Hi performance rudders. The Defiant used the front mounted rudder for quite some time. What ever you deside to do with your bird is no skin off my nose. and God willing not yours.

This comment Is just me. Vortalons were first put on the Variez. They worked great for them. became Mandatory change. Then they were tried on the Long-EZ. A little better slow flight quality. It was up to the builder to use them. Later it became mandatory. Personaly I have noticed no change in slow flight control. But I have them. One thing I changed that did make an improvement, was vortex generators on my GU canard. They slowed my landing speed by 8 knots, and I lost no speed. My canard never lost lift in the rain even without them.Have fun building, and all your layups be perfict.

If the phone don't ring. It's me

Link to comment
Share on other sites

"I see" said the blind man as he picked up his hammer and ....saw:D

 

So the guys without the winglets may look better, but low speed performance is compromised eh?

 

I don't think Im going to get all excited about making sure the winglet is exact. I may to modify it a little....

:bad:

 

Thanks...

 

It's funny reading that 25 year`old stuff, like it was yesterday..

 

Kevin

Back to building... #618 Cozy MK IV

 

My Cozy web pages, courtesy: Rick Maddy... :cool: WN9G :rolleyes:

Link to comment
Share on other sites

Well,............I agree with Dust, I like the way the winglets look. To me, the wing would look incomplete without them.

 

Perhaps it would be nice to install an "Ice Skate Blade" on the underside of the winglet.(For tip scuffing)

Joseph@TheNativeSpirit.Net

I am Building a Jo-Z IV StarShip.

 

What Do YOU Want?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information