Hey everyone,

I'm curious if anyone here uses telltales on wings and what your experience has been.

Either home made or purchased in sailing stores www.amazon.es/AB-Tools-autoadhesiva-puertos-estribor/dp/B098XB8J2Q

A few questions:

-Do telltales work effectively on wings, given the different airflow dynamics?
-How many do you use, and where do you place them for optimal feedback?
- Any specific materials or attachment methods that work best?
- Have you noticed a significant performance improvement by using them?



Would love to hear your insights and experiences!
Thanks!

I always found them greatly helpful in dinghy sailing and especially racing. You can see the shadow of the telltale through the sail, wing, etc. or, better still, attach them to a window. I often thought about putting them on windsurf sails and kites, but didn't ever get around to it. I am keen to try them on wings though. I disagree with the interpretation of them in the diagrams though: That was the old idea (that both sides streaming backwards was optimal), but nowadays, with updated sail theory and practice, it is considered optimal to have the windward telltale streaming upwards and leeward side streaming back. I would place them as close to the strut as possible (so you can see them on both tacks). And they need to be just far enough back from leading edge to get laminar airflow over the windward side. You don't need to buy them. I used to spray waterproofing on to about 20cm of woollen thread and thread it through the sail halfway. Not very good if you put them through a window though. Still something like in FranP's link would be easy enough to make, as AB Tools prices are exorbitant and it can be quite useful to haves some on the leach (back) of wing and some further towards the wing tips.

I think you're going to see more turbulence than you think wherever you put it.

FranP said..

-Do telltales work effectively on wings, given the different airflow dynamics?
-How many do you use, and where do you place them for optimal feedback?
- Any specific materials or attachment methods that work best?
- Have you noticed a significant performance improvement by using them?

Yes they work fine. Use thin wool. Depending on the sunlight, black colour is visible enough through thin white or CZ material canopies.

Install them in straight rows from leading edge to trailing. In one row spaced about 300mm apart. Windward and leeward sides - but not directly in line for a clearer view of leeward telltails. One row across one canopy will tell you a lot about the flow. Or do both port+starboard sides to see differences in the upper or lower canopy at the same time. I've only installed rows mid each canopy, all 4 sides, to see major stalling or flow. You could try rows closer together if you want more info such as stalling around the tips or middle strut. Add some leech tell-tails if you are curious.

Not really any perf improvement. It's a learning tool. Handy if doing sail modifications or making your own sails. They give you a visual for what you will typically feel via your body. eg. to try make sense of different techniques or to explain why some sail feels bad.

It's interesting to see the windward side tell tails pointing forwards behind the leading edge tube, and the transition point where the flow splits forward and aft. It's typically around the mid point, but moves around as the air AoA changes.

When you suspect leeward side flow stalling while pumping in low wind speeds, then it's difficult to watch the telltails at that time. But it's easy to see the leeward side luff entry stall happening when you over-sheet the sail too much.

On sails I've used them, with test rows half-way out each canopy, during normal upwind sailing, there is attached flow all the way across the leeward side, and on the windward side with a single skin sail, there is attached flow in the rear half. Leech tell-tails flow all the time.