Winglets

[Fly Boy 3]

over the years I have seen many models with small vertical winglets at the end of each wing tip. Do these add to flying qualities or just look cool ?  Thank you.
 

 

[PDB]

Here's one reason for them on wings https://forums.modelflying.co.uk/index.php?/topic/53659-slope-wing-yaw-wobble/&ct=1711558523

[GrumpyGnome]

Sometimes called Side Force Generators - supposes to help in things like knife edge. Just about all indoor aerobats have them. No idea if it's just fashion!

[Simon Chaddock]

It rather depends on what you want or expect winglets to do.

A GG suggests they can be useful to create side area at which they can work well but If you are trying to improved the aerodynamic efficiency of a wing by controlling the tip vortices then they most unlikely to make any practical difference at model sizes and speeds.

After all such winglets benefits are only measurable, and then only by a few %, on airliners on long duration accurately controlled flights.

[Martin Harris - Moderator]

They've been almost universally adopted on high performance full size gliders at significant cost so there may be measurable benefits on larger models.  To my mind, they are an ugly addition to the beautiful clean shapes that competition gliders evolved to in the glass fibre age.

[john davidson 1]

They control the vortices from the tips which cause drag

[Andy Stephenson]

On full-size airliners, winglets reduce vortices by a significant amount. So much so, that it can bring down the time between runway movements where lingering turbulence is no longer a safety risk.

[Jason Channing]

12 hours ago, Andy Stephenson said:

 it can bring down the time between runway movements where lingering turbulence is no longer a safety risk.

That's not true as ATC do not know which aircraft have Winglets added or not. ATC Separation is either based on time or distance and has not changed. And there is nothing to enter on a flight plan saying winglets added or the type of the winglets.

 

[Andy Stephenson]

Can not does!

[Brian Cooper]

From a practical viewpoint (with models) they slow down the roll rate a bit, but increase the rudder response. 

Arguably, they are best employed on 3D aerobatic models. 

 

Some look cool, some look ugly. 

[RedBaron]

In the case of full size gliders the vertical wing tip extensions control the airflow at the wing tip and in doing so improve the performance of the outer sections of the ailerons considerably. Also the overall wing tip drag is reduced, and thus it follows that the overall glide angle is improved.

 

With regard to models one might debate this at length, but perhaps it is permissible to say that the bigger the wing span the bigger the effect will be.