how protect vane in a windvane

[Ramona]

No ones looking for lift with their windvanes. The windvane works by having the wind pushing the blade over when the air is not equal both sides. Usually on a tilted axis so that power reduces as the blade gets near 45 degrees. There is a reason all windvane manufactures use flat sided vanes. I have found a spoiler on the rear edge reduces the nervousness and is pretty much the opposite of a foil with lift.

[model 10]

Originally Posted by Ramona

No ones looking for lift with their windvanes. . I have found a spoiler on the rear edge reduces the nervousness and is pretty much the opposite of a foil with lift.

That is what they sometimes do to the trailing edges of aircraft control sufaces.

[AiniA]

We had corrugated polycarbonate vanes with our Monitor and they were wonderful, did more than 40k NM with them and the only thing we had a problem with was the tape around the edge. We had the larger vane up in winds where it should not have been (<45 knots) and it bend a lot but still worked fine. A problem, depending on the particular install, is that it is hard, and potentially dangerous, to change to the the smaller vane in the conditions where you might want the smaller vane.

[a64pilot]

The history of the “Gurney flap” I find very interesting, it has been adopted heavily by Boeing and other Helicopter manufacturers as a way to keep airflow attached at very high angles of attack.
https://en.m.wikipedia.org/wiki/Gurney_flap

Goes to prove that every now and again, even Jim Bob comes up with a brilliant idea that none of the big boys can,
For “nervousness” or control sensitivity, a square trailing edge as opposed to a tapered one is very effective

[model 10]

Dan Gurney was not a "Jim Bob". He was the only American to ever win a Grand Prix in the rain in his own car. He also said everybody should be able to drive their cars on Sunday without a muffler.

[a64pilot]

Gurney was most definitely a Jim Bob.
Jim Bob does not mean stupid, more likely self taught as opposed to MIT.
Jim Bob is no fool, quite intelligent and very often underestimated due to his lack of education and or title.
He came from a very well educated family, although he was not.

Chuck Yeager was a Jim Bob, Scott Crossfield was not as an example

[model 10]

Got it. Sounds southern though.

[Snowpetrel]

Originally Posted by Ramona

No ones looking for lift with their windvanes. The windvane works by having the wind pushing the blade over when the air is not equal both sides. Usually on a tilted axis so that power reduces as the blade gets near 45 degrees. There is a reason all windvane manufactures use flat sided vanes. I have found a spoiler on the rear edge reduces the nervousness and is pretty much the opposite of a foil with lift.

What you are describing as the wind pushing the blade over is technically called 'lift'. The spoiler (gurney flap) increases lift dramatically but at the cost of lots more drag.

I am pretty impressed with your homemade windvane. Looks great.

[a64pilot]

Originally Posted by Ecos

Got it. Sounds southern though.

They often are.

[Snowpetrel]

Originally Posted by a64pilot

Many years ago, as in WWI era aircraft wings were very thin, pretty much plates. The idea was thin wings have less resistance and you can go faster. However being thin they are very weak and flexible, necessitating a lot of struts and wires and other braces to keep your wings from disintegrating. then I’d guess about the 20’s or maybe as late as the 30’s it was discovered that thicker airfoils performed much, much better allowing higher angles of attack etc before stalling and being thicker, it was easy to internally brace them and make them strong and speeds went way up, without the external bracing they were much less resistance too.

I don’t know about size, but this Viper 500 wing has zero dihedral, is fully symmetric and is stronger than you can imagine and very lightweight.
https://www.towerhobbies.com/cgi-bin...BoCkjYQAvD_BwE

Comes in Read or white, already prebuilt, covered etc. it does have thin strip ailerons though that you would need to install.

The Viper 500 is a very, very fast little racing airplaneAttachment 175001

That wing section looks pretty neat. And its a very reasonable price. It would be fun to test one of them out.

[a64pilot]

It’s very strong and a very efficient airfoil coming from a racing airplane.
However I think I’d want to Epoxy some “fish plates” to the wing where it would be mounted and then drill the mounting holes and Epoxy in carbon fiber or aluminum tubes to handle the compression loads from the bolts.

It could be building a nuclear powered wristwatch though, by that I mean something expensive and complex but works no better than the simple product.

However if you ever run into a windvane that loses “bite” due to a sudden wind shift or whatever, an airfoil ought to help in that situation and keep it steering.
I don’t know if that ever happens with a vane or not as I don’t have any experience with one.

[sardinebreath]

Originally Posted by Snowpetrel

It has to match it, but by moments about the pivot rather than weight, so if the vane is taller it's total weight needs to far lighter than a shorter vane.

I usually balance it by experiment, I want it to return to upright, but slightly slowed due to air drag. My first set of vanes where far too light and in light airs lost sensitivity. I drilled a small hole and put a heavy shackle through it near the top of the vane, and suddenly it started steering in a whisper of wind.

Seems counter-intuitive that a heavier vane would be more sensitive in light wind. Surely initial movement is going to be greater the lighter the vane. I suppose putting weight at the top of the vane would help counteract resistance of the counterweight, but only once the wind had managed to knock the vane off vertical--and that is going to be more difficult the heavier the vane. But I accept data supplied by experience over my own abstract conceptualizing so I reckon I will try the weighting thing once I get a vane and am wrestling with light air performance.

[hodgmo]

The Atoms wind steering system used a vane made from a thin aluminum plate. It is a robust set-up, and works well.

[wingssail]

Originally Posted by xxhat

All wind vanes use a wood vane to detect the wind and adjust the tiller.


This wood vane has to be light. What is the best way to protect the wood vane from cracks or breaking ?


1. Expoxy but this may add too much weight


2. varnish


Any other ideas ?

We use a Monitor Light Air vane made out of some kind of very light weight plastic, possibly foam board, with tough plastic skins. (have attached a photo of it). It came with the used Monitor we bought in 1995. We also have two smaller, plywood, vanes which we intended to use in windier weather, but the plastic one has actually been through everything, and I mean everything, and now we never change it. We've sailed with the Monitor with this lightweight vane 99% of the time for over 55,000 miles, winds up to and including 50 knots, and sometimes it looks a little bendy, but its been fine. Due to its increased area it is very responsive even in light winds. We always put it away when not underway.

[wingssail]

Originally Posted by Ramona

No ones looking for lift with their windvanes. The windvane works by having the wind pushing the blade over when the air is not equal both sides. Usually on a tilted axis so that power reduces as the blade gets near 45 degrees. There is a reason all windvane manufactures use flat sided vanes. I have found a spoiler on the rear edge reduces the nervousness and is pretty much the opposite of a foil with lift.

The force produced by the wind which pushes the vane over is lift. An airfoil section might produce more lift and work better however wind vanes are mostly flat and work pretty well as is.