Paddle flutter

Flutter…my take
I never noticed any flutter with any of my paddles. It wasn’t until I got my ONNO wing that I noticed flutter. Not on the ONNO (Zero flutter) but on my wood Bending branches paddle. I found it quite annoying and even with some adjustment, I had some flutter.



Andy

Some 411 on Flutter
Anyone who has paddled a wing paddle for a while and then tried Euro paddle will tell that all the Euros flutter. They feel like limp noodles compared to the solid feel of a wing. But it’s all relative.



I will sometimes swap paddles with others who want to try a wing. I am always shocked at how useless I feel with a Euro and I learned on one. It takes me a few minutes of practice just so I can keep up with the guy trying my wing for the first time. I also realize how much balance I get through the wing paddle. I would say just about all my stability comes through the wing paddle. I suppose this is why wing paddlers gravitate toward narrower, more efficient kayaks and can take them out in big water with ease.



I am sure the other guy is freaked out by how different a wing feels too. It took me a couple weeks of commitment to transition from a Euro to a wing before the technique became second nature. But flutter is non-existant with a wing. Perhaps by understanding why wings don’t flutter it will help to understand why Euros do.



Euros lack stability in the water because of flutter. Evidence of flutter are vortices being released from both the inboard and outboard edges of the paddle at slightly different times. The vortices are easy to see as little whirlppols, but the fluctuations in release time (oscillations) are probably too close to see but you feel them as flutter. Once started these oscillations build and increase through the stroke. They should also become more evident when you pull harder. Picture the Tacoma Narrows bridge twisting back and forth in greater amounts over time. Flutter sets up and grows the same way. All Euros release these vortices, which represent energy wasted by the way. Its simply your energy being wasted to stir the water. Most people become used to the flutter in their paddle and it makes little difference to their paddling enjoyment. Its not until you change paddles that you start to notice differences.



Wings shed vortices only from their trailing edge as a product of generating lift, like every foil operating within its normal range. Oscillations never get started and there isn’t flutter because vortex release is only on one edge of the blade. This assumes that one uses a wing correctly. By the way, this single trailing edge vortex is a necessary product of generating lift. This is still a far more efficient situation than wasting energy through twin oscillating vortices as a product of generating drag like with europ paddles.



A properly shaped Euro paddle (one with spoon) combined with a wing paddle technique can be made to only shed vortices from its trailing inboard edge eliminating flutter. I challenge you to find that paddle because there aren’t many blades out there that are spoon shaped. I have one from Simon River Sports and it was my favorite paddle before I committed to a wing.



I agree with someone else who said they do not like dihedral (like in most Werners). Dihedral may reduce flutter a wee bit by putting the center of drag a few centimeters behind the center of the shaft, but the paddle becomes less efficient in the water and this shape eliminates any chance of limiting vortices to just the trailing edge. The dihedral shape is also the opposite of what you would want if using torso rotation with the paddle taking a natural path that moves away from the hull. This Werner-style dihedral is a vortex making machine. It is designed for pulling straight back with bad technique all the while shedding larger votices than a flat blade.



Spoon is a better shape for a Euro blade to generate some lift (instead of just drag) when combined with torso rotation. By the way the term dihedral as Werner and other paddle makers use it is technically incorrect compared to the rest of the fluid dynamics world.



Wing paddles have real dihedral. The full blade is angled away from the shaft at a significant angle just like wings on an airplane angled upward from horizontal. This puts the center of effort significantly behind the shaft center adding to its stability while moving through he water.



Crank Shaft paddles accomplish the same thing as real dihedral, by putting the center of drag significantly behind the paddlers hands. This is probably a better solution to decrease flutter in euro paddles than Werner-dihedral, but the shape of most blades will never eliminate it completely. Crank shafts have other issues that justifiably keep most experienced paddlers from using them. I think the Epic website has a short article that explains this better than I could. Some folks with injuries do claim more comfort from crank shafts so they do have their place.



Some people use paddles with a crank shaft and Werner-style dihedral. This is like wearing a belt with suspenders. This setup still has plenty of flutter although it should be dampened more than either solution alone. Its a personal choice whether all the cons of this setup justify the gain in flutter dampening. By now you know that I think this is the opposite direction for anyone intending on paddling more efficiently.



What I don’t know is why a paddle builder has not tried real dihedral (not Werner dihedal) on a Euro paddle. I would think this would be an effective solution to dampening flutter while allowing a straight shaft and a flat to spooned blade. Based on my experience with a wing, I can not see how this would significantly effect overall versatility of the paddle. There would be a little less stability when paddling backwards, but it is very manageable for the small amount of time one needs to stroke hard in reverse.



Maybe the idea of a spoon shaped blade, with real dihedral, mated to a straight shaft, combined with good torso rotation is too close to what a real wing paddle is. This setup is in effect just a poorly designed wing. Anyone who understands the mechanics of a good stroke and paddle fluid dynamics well enough to see the benefits of this setup is likely to already be paddling a wing anyway.



I may have just pissed off everyone who paddles a blade with false-dihedral or a crank shaft. But the truth is these features are just band aids designed to dampen flutter. But they do so at a cost that many feel is worse than the problem they are supposed to fix.


Well said! NM

please try a wing
Wing paddles are so efficent at really grabbing water with no flutter

Experiment in Your Kitchen
I hope I used the term spoon correctly. I think of a spoon shaped blade as being curved from the outside to the inside edge much like a dinner spoon. The key is that the concave face (the hollow area) is the power face, facing aft. This shape has a better chance maitaining flow attachment around its edges and forward face. This is more true if alowed to travel outward away from the kayak like when you rotate your torso properly.



False-dihedral like on Werners actually creates concavity on the forward face of the blade. Its a big hollow area that must be filled with water with every stroke. Water can not make the turn around the blades edges without losing seperation, creating vortices and wasted energy. You are stirring the ocean with every stroke.



You can experiment with this at home. Fill the kitchen sink with water. Spinkle some pepper into the water so you can see how the water moves. Then use a large serving spoon to replicate a paddle. Do one stroke through the water. Watch how the pepper spins. Try different angles of attack. Then turn the spoon around and repeat.



You should find that the least amount of vortices are formed and the most lift generated when the concave face of the spoon is the power face and it is stroked at an angle outward with a few degrees of angle of attack.



Might as well break out the other kitchen implements to try diffent blade shapes. Maybe try using chopsticks or a spoon handle to repliate a Greenland paddle. Remember you are trying to feel the most resistance through the device with the least amount of spinning vortices, which represent wasted energy.



Piss the cook off. Bend the spoon to put real dihedral in the face. Does that reduce flutter. You can try out crank shafts and all kinds of shapes by doing a little modification to your expensive cookware. Actually cheap nylon utensils made for non-stick surfaces are great to experiment with. Cut up some spoons, maybe a spatula to look like popular paddle shapes and try them at home. Your wife will think you’ve lost it.

I tried today in the wind
I had 10min previous experience with a wing. The el cheapo Speadwing came yesterday so this morning off I went. This is picking up a wing post many years with a GP. There is no doubt that I like the wing better than a typical euro. The paddle seemed very short at first but moved the kayak well. I’ve go what I think is good torso rotation so I just let the paddle do its thing. Only one time did I do wrong and the paddle dove and I could feel it pulling me that way. I did carry a GP storm on the bow :slight_smile:

Dihedral

– Last Updated: Apr-11-08 11:19 PM EST –

This is all nice, though I don't think you are using the dihedral term correctly. Dihedral is the V formed by airplane wings looking from the front of the plane. It isn't for lift, it's for roll stability. The Werner paddles you speak of have true dihedral, and for the same reason. Being pulled straight back through the water just like the plane is being pulled straight down by gravity through the air.

You are talking about something entirely different with the wing paddle, since it is flying sideways through the water. No dihedral involved. What you are talking about is more like the airfoil shape of the wing and where the center of lift is.

Mike

Wing paddles are surely wonderful
in their proper environment, but as for crank-shaft paddles with “Euro” blades, I have one, and it has never fluttered.



How long will we wait before a wing paddle is used in a whitewater slalom race??? Probably until after the end of time. Wing paddles are great for mostly straight-line progress in unobstructed environments. When I get into that, I will surely get a wing paddle. But for whitewater and twisting flatwater rivers, I already have an efficient non-fluttering, high angle paddle. Developed back in the 80s by people who slam around rivers at a high rate of speed.



Henceforth, please do not suggest that wing paddles have any general usefulness. And I will never suggest that high angle slalom paddles are useful for flatwater racing or ocean cruising.

Agree 100 percent
I always would have to correct my stroke using a euro so it wouldn’t flutter, but using both my large wing and my mid that I just got from ONNO, I have never experienced a flutter.



Cheers,

JackL

Come to think of it, I had an old
Harmony with a straight shaft and dihedral blades.



I wonder why I never experienced flutter with that paddle… I didn’t like it that much, but it didn’t flutter, and it didn’t feel like a “wet noodle.”



Flutter does seem to be mostly an operator error problem. For which wing paddles are the solution ONLY if a wing paddle meets all the user’s requirements in the chosen environment.








Huh?
That analogy only makes sense if the plane has zero forward speed.

mhackett and I have the same definition
of dihedral. Obviously that definition is a bit different than some paddle makers.



Black Vultures soar with wings flat, Turkey Vultures soar with a shallow ‘v’ - or dihedral.



I always thought ONNO paddles had a dihedral shaped power face, as do Werners.



What is a ‘false’ dihedral?

Well, yes,

– Last Updated: Apr-13-08 12:04 AM EST –

it's certainly true the paddle doesn't also fly downward through the water, at least not very far.

http://en.wikipedia.org/wiki/Dihedral

It does appear from that and some other things I found that the stabilizing forces aren't quite the same for the paddle as they are for airplanes, at least not entirely anyway.

The main point I wanted to make is that dihedral is not for providing lift, it's for stability.

Mike