I was wondering when riding last week: do you create extra lift in fast turns? Sometimes when I don't have enough speed in a wider turn and then sharpen it, it feels like I'm creating more momentum. Sort of a g-force feeling. Is this true or is this just a placebo effect?

I say yes possibly.

Banking over reduces vertical lift of course.

But when u tighten its the same as spinning on a chair and moving arms in to speed up..... or an ice skater tucking in to speed up. You tighten, your rotational speed increases. ie- speed up around the axis of the centre of the turn, but travelling less distance so hmmmmm how much does the water speed of the foil increase.

So more lift as long as you dont bank over more at same time and as long as the radius reduction doesnt outweigh the speed increase.
Plenty of low altitude plan crashes exactly like that.

All this only a theory

Edit - hang on you said g-force now I'm wondering that..... or lift?

Mebbe what you are experiencing here is the same effect as pumping the foil? To tighten your turn you are putting weight on the back foot which is raising the foil.

To imperfectly test that theory, ride with your two feet side by side in a forward stance at the balance point of your board, lean your body to turn, see if you experience same result.

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Fishbone80 said..
I was wondering when riding last week: do you create extra lift in fast turns? Sometimes when I don't have enough speed in a wider turn and then sharpen it, it feels like I'm creating more momentum. Sort of a g-force feeling. Is this true or is this just a placebo effect?

It's true, I learned this when I was learning to connect DW bumps. I started to do tight little S-turns to generate speed and lift to connect bumps instead of straight pumping. I liked the experience a lot better too.

It's real and this video helps explain why that makes foil placement so important:

Some foils do it a lot more than others. Some like it, some don't. I love it.

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BullroarerTook said..
It's real and this video helps explain why that makes foil placement so important:

That doesn't make any sense. He combines together the forces from each foot into one force and then the weight of the foil/board into another. But he leaves out combining the riders weight and board/foil weight to create another single force. Ultimately it's the position of the force from the combined board/foil/rider weight versus the lift from the front wing (ignoring any stabiliser effects) that affects the balance of the foil.

In level flight of the centre of gravity of the board/foil/rider will be in the right place to balance the lift from the front wing. As he says, the downforce during the turn will increase but that applies to the total board/foil/rider system. It won't cause the combined downwards force to change position.

If it was balanced going into the turn then it wouldn't get out of balance during the turn. He says the extra leverage from the board weight out in front is significant but ignores the corresponding increase in the riders weight behind the wing creating a counteracting torque.

Agree that his explanation is not correct. Any increase in g-forces during the turn affect the whole system, so the position of the combined forces does not change, at least in the simplistic approach he discusses. That said, his argument that having the forces aligned makes some sense - adjusting a balanced system should be more intuitive and easier than one where the weight vectors for the gear and the sailor are not aligned. You'd need to take into consideration that parts in the water effectively change their weight, though. A light large volume front wing (one that floats) effectively creates an upward force in the water, not a downward force like in his test.

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Fishbone80 said..
Sometimes when I don't have enough speed in a wider turn and then sharpen it, it feels like I'm creating more momentum. Sort of a g-force feeling. Is this true or is this just a placebo effect?

Maybe it's a true perception (more g-forces) interpreted incorrectly (as more speed). You g-forces definitely will go up when you tighten the turn. Say you tighten it so you need to lean 45 degrees to be balanced - then you feel 1.4 g, the (vector) combination of gravity and centrifugal forces. But I have no clue turning sharper actually makes you go faster. It sure works on ice skates or skateboards, but I never understood why.

Looking at GPS tracks from winging, the top speed in jibes on flat water is usually around 130 degrees to the wind (which makes sense, since this is the fastest angle if you have enough power). On waves, it's often closer to 180 degrees, which reflects the push of the wave. So if you sharpen turns to better align with swell, that alone should give you a speed boost.

Are we talking lift (vertical / ability to maintsin altitude with no change to power or body position)

Or "g-forces" which i take to mean the sideways force felt in a turn same as cornering fast in a car etc

When you tow alot you'll notice you create more speed from carving turns than pumping and once you discover that it will translate into all your foiling genres plus the other advantage once you start doing these top-to-bottom carves you start using the higher energy part of the wave. Too many people just shoot done the line and try and pump around sections. Adam Bennetts pointed this out to me on my indo trip with him last year. It just changed everything for me. Just watch any video of Adam he never just pumps down the line he is always carving top to bottom turns creating incredible speed. It's Surfing 101 Foiling is no different. So to answer your question Fishbone:- Yes carving turns is the best way to create more speed.

But was he talking about wave riding? Just tighten radius seems to be a rather different question

No same same , you are way over thinking it. The fastest way to get from A to B on a foil is not a straight line . Just watch the downwind crew. Driving hard off the front foot into a carving turn then straightening up and unweighting letting the mast lift high to reduce drag and let it run is like turning the knob on the nitrous, it's a skill but when you learn it you'll understand how these DW guys consistently pull sub 2min km's. Apply the same principle to the Ding DW and Prone/Sup Surf with tight-as-you-can carving turns and the world is your foil oyster.

This is one of the best questions I've seen on the Breeze in a long time. Good job Fishbone
I was wondering when riding last week: do you create extra lift in fast turns? Sometimes when I don't have enough speed in a wider turn and then sharpen it, it feels like I'm creating more momentum. Sort of a g-force feeling. Is this true or is this just a placebo effect?

Great to see al the replies. I think I'm not sure how to describe the feeling (lift or speed), it's more that I don't stall because of the extra boost (as described in the post above, thank you Piros). And I only ride flatwater. With no technical background at all, I have a 'theory'. Maybe it's besause you go on a straight line and turn sharply, the sudden change in trajectory creates downforce which translates into energy into the board/mast/foil? Like a racecar which is pushed down on a race track in corners?

And I only ride flatwater. With no technical background at all.

Ever had a girlfriend say stop talking you are ruining everything............

Hahahahaha

I have found from dockstart pumping experiments that an emergency turn can save a bad low speed launch by giving you extra lift or speed.

My theory was that a turn gives the outer wingtip a massive increase in velocity (while the rider speed stays rather constant) which gets it making lift and energized such that you can load it and pump off it. May only apply when you are dancing in and out of the low end of the foil speed range.

So my 2 cents... (you get what you pay for)
Is to look at skate board pumping. Side to side, flat ground, slalom type pumping. (not the up and down terrain type) I believe the slalom pump generates the forward thrust from the a back foot. The push and or pull coming out of the turns, from the rear truck angle giving you the ability to get SOME forward movement.
Same way "tightening the turn" or "the turning pump" with your foil, could possibly transfer power from your body (rear foot?) to the rear Stabilizer acting like the truck angle on the skateboard, somewhat as a propeller to push water and to give you a little extra forward thrust. That said, I really have nothing to back this up with, so yeah, just another opinion.

I am doing these small turns on a wave face while wave windsurfing, to keep the speed going. Often, if you would just move in a straight line, at the speed of the wave, it would not be enough to make the board plane properly. Hence the wiggle type of moves that make the board cover a longer distance and stay planing fast and free.

Lots of different techniques in this clip. The relevant part is 04-10 seconds. Surfers do something like that as well.

Like @Powis said: "when you are dancing in and out of the low end of the foil speed range".

Great video. The same basic physics that allow you to generate speed on a surfboard by wiggling and pumping should be at play with a foil. Here's a couple of simplistic attempts to explain this (with some pointers from Bing Chat):
- Leaning into the turn (and leaning more when tightening a turn) creates a centrifugal force. That creates an matching force in the ooposite direction. If the lean is partly forward, the force has a backward component, so the opposing force will have a forward component, which accelerates the board.
- The centrifugal forces from the lean increase the total force on the foil. One way to think of it is that it increases the pressure on the water below the foil, thereby creating extra lift. While turning, the foil is angled, so part of that lift force is horizontal. The similar situation is when foil racers angle their foils to go faster.

Those are just bits and pieces. The issue of centrifugal force and the direction of force vectors in jibes and turns is quite interesting.

interesting, my 2cents:

Turning prob does a few things
- rider experiencing centripetal force as you acceleration towards the centre of the turn so there is the 'feeling' of acceleration
- accelerating the outer tip so flow speed on one side greater than other so this can tend to accentuate a turn and partly why big span foil feels locked in
-some foils don't have matched anhedral front to back (ie a anhedral front foil with a flat race tail) and so in a banked turn the forces are not balanced so rider may need to correct a change in pitch centre by moving forward or back, upward front pitch is perceived by some people as more lift but actually you have less lift but you are dealing with pitching moment. Your total lift force is reduced so you are also pitching nose up a tad (intuitively)
-the kicker is that in general when turning you are retuning to your power source (ie usually a wave) and that's prob why the fastest course is to turn because it's all about being in the best part of your power source to keep speed and momentum

So much bad physics here. YES all these turns are keeping your speed up like pumping but some of the reasoning is very off.

Your foil can only make lift along the axis of the mast. So as soon as it is not level, your vertical lift reduces.
ANY wing and well known to EVERY pilot is if you bank an aeroplane (or your foil) with no other input you lose altitude. In a plane, you have to increase elevator or throttle to maintain the same altitude when turning. Turning too tight with no other control input and you will crash. You fall out of the sky.

So all this talk about just turns increase lift is sorta disingenuous given the previous discussion. It is some other input during the turn that is increasing lift, not just the banking over the foil. The reason I say that, is the original question is: if you are turning and suddenly decrease the radius does it increase lift.
No it does not. Its not the radius decreasing that causes it , its some other force. Same as the aeroplane. Its the whole package of what you are doing with back foot pressure etc. And for many people here, the wave giving you energy. I repeat - if you suddenly lean the foil over, you lose height. You have to. Its physics.

Chemtrails / boardsurfr onto it. And JU particularly your last line

I just had a long discussion with my lovely wife, who is a much better winger than I'll ever be, about banking the foil. She has no doubts that turning on a wave will give her extra speed from the wave, and her GPS tracks show that very nicely. She strongly doubted that a similar turn in flat water would cause acceleration.

Mark's point about loosing vertical lift when you bank the board to turn raises some interesting questions. As a relative beginner still working on jibes, my understanding was that you keep the board relatively flat on a beam reach, and then bank it to leeward to turn downwind for the jibe. In the turn (and more so in sharp turns), the increased angle would lead to loss of vertical lift, so the board would slowly go down onto the water. When turning the power off to move the wing, the foil looses speed, which also leads to loss of lift. All that would have to be compensated for somehow if you want to foil through a jibe.

Do centrifugal / centripetal forces play a role there? I have no clue. I can see that they do not play a role for airplanes, but foils are in a (nearly) non-compressible medium, which could make a difference - more similar to a skateboard or snowboard in a half-pipe (also not something I know much about). The elasticity of wide hide aspect foils, similar to formula fins, may also come into play here.

Looking at videos from good to world-class wingers, though, I got the impression that original understanding was incorrect. Typically, they have the board angled even when going in a straight line. In a jibe, the board angle is similar, except that it is too leeward instead of windward. So that means the vertical component of the foil would be similar.

If that is indeed so, it raises another interesting question: why can we wing in a straight line with the board banked to windward, if banking the board to leeward at a similar angle causes it to turn? This one is perhaps easier to answer for windfoilers .

When foiling on flat water and wanting to go slow (like for example when following and filming a student with a much bigger front wing who is not yet riding too fast) I do the S turns so that my 631 cm2 foil would not fall down. In a situation where there is enough power in the wing I can slow it down to some crazy low speeds while going just in a straight line, but in quieter moments the S-turns and more active riding helps to keep the foil working and flying.

Again, I think in my example the key is that by doing the turns I am covering quite a bit longer distance than I would do while riding in a straight line. It's like pumping, but not only up and down but from side to side as well. It's a 3D world after all, and whatever means you'll find that help you to put extra energy in, do it. Of course you can accelerate out of the turns if you want.

Scroll to 00:44 to see an example of what I meant.

You can analyse the **** out of it but seat of pants turning a foil is Feckn awesome. You accelerate out of turns, so addictive

Flex in the mast and foil set play a large part in creating speed by carving! This applies to flat water and wave riding and some sets just give **** and others are like powered.

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Mark _australia said..
So much bad physics here. YES all these turns are keeping your speed up like pumping but some of the reasoning is very off.

Your foil can only make lift along the axis of the mast. So as soon as it is not level, your vertical lift reduces.
ANY wing and well known to EVERY pilot is if you bank an aeroplane (or your foil) with no other input you lose altitude. In a plane, you have to increase elevator or throttle to maintain the same altitude when turning. Turning too tight with no other control input and you will crash. You fall out of the sky.

So all this talk about just turns increase lift is sorta disingenuous given the previous discussion. It is some other input during the turn that is increasing lift, not just the banking over the foil. The reason I say that, is the original question is: if you are turning and suddenly decrease the radius does it increase lift.
No it does not. Its not the radius decreasing that causes it , its some other force. Same as the aeroplane. Its the whole package of what you are doing with back foot pressure etc. And for many people here, the wave giving you energy. I repeat - if you suddenly lean the foil over, you lose height. You have to. Its physics.

Chemtrails / boardsurfr onto it. And JU particularly your last line

Agree 100%.

I have felt foils that loose speed and side slip in jibes.

I have also felt foils that seem to almost go faster in the opposite direction, the harder I turn. I love this and cannot figure out what design factors cause this. I just know when I find it, it's the one for me, and I buy it. I have opinions on why, but opinions are not facts, so I'm not going to share.

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Mark _australia said..
So much bad physics here. YES all these turns are keeping your speed up like pumping but some of the reasoning is very off.

Your foil can only make lift along the axis of the mast. So as soon as it is not level, your vertical lift reduces.
ANY wing and well known to EVERY pilot is if you bank an aeroplane (or your foil) with no other input you lose altitude. In a plane, you have to increase elevator or throttle to maintain the same altitude when turning. Turning too tight with no other control input and you will crash. You fall out of the sky.

So all this talk about just turns increase lift is sorta disingenuous given the previous discussion. It is some other input during the turn that is increasing lift, not just the banking over the foil. The reason I say that, is the original question is: if you are turning and suddenly decrease the radius does it increase lift.
No it does not. Its not the radius decreasing that causes it , its some other force. Same as the aeroplane. Its the whole package of what you are doing with back foot pressure etc. And for many people here, the wave giving you energy. I repeat - if you suddenly lean the foil over, you lose height. You have to. Its physics.

Chemtrails / boardsurfr onto it. And JU particularly your last line

Thank you. This has been driving me nuts. Any four forces of flight diagram would show this. If the rider is feeling an acceleration it's because something is adding thrust. Could be the wave, could be the wind, could be a pump. A banked foil divides lift between a horizontal and vertical component. It's literally student pilot 101.

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Seastudent said..
If the rider is feeling an acceleration it's because something is adding thrust.

Maybe, but perhaps not. If you change from a straight line course to a turn without changing speed, you add angular acceleration. The same when you tighten a turn. The rider will perceive this as additional pressure on the legs. You can feel the same thing when going into a jibe on windsurf gear after a speed run, even though you actually start loosing speed right away.

For the sake of argument, let us assume that the added angular (centrifugal) forces are not just perceived by the rider, but transmitted onto the foil. That means the total forces on the foil increase. If flight height remains constant, we also know that the foil will "push back" with exactly the same amount of force, in exactly the same direction (following the mast). The vertical component of the force has to be equal to rider + gear weight, the horizontal component must be equal to centrifugal forces.

That raises the question why the lift ("push back") by the foil would increase. Two possible reasons are:
(1) The increase in total force on the foil acts similar to pumping, causing the foil to accelerate.
(2) The rider actively manages flight height and increases the angle of attack of the foil, thereby increasing total lift.

DWC's observation about different foils points towards reason (1) playing a role for some, but not all, foils. Initiating the turn more mostly with the back foot (when previously sailing with a balanced weight distribution) would cause an increase in AoA (reason 2).

For many jibes, the discussion above is irrelevant, because the absolute banking angle of the foil does not chance much - it just switched from a tilting to windward towards tilting to leeward. However, the discussion remains relevant with respect to tightening a turn, when the angle suddenly increases. I get the suspicion that the reaction of the foil to such increases is closely linked to the reaction to pumping. If so, foils that are "easier" to pump should also react better to changes in turn radius.

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DWF said..
I have also felt foils that seem to almost go faster in the opposite direction, the harder I turn. I love this and cannot figure out what design factors cause this. I just know when I find it, it's the one for me, and I buy it. I have opinions on why, but opinions are not facts, so I'm not going to share.

I agree with DWF, that a hydroplane's turning (horizontal lift) response, after a roll increase, is a big deal, and a highly desirable characteristic for carve free-ride type riding. I would be happy to learn DWF's opinion/theory.

I can relate to boardsurfr's two proposals that, when all else is equal (eg. mast, fuselage, stabiliser foil, rider, conditions) that different foils will 1. "push back" turn with different lift response when subjected to an increase in horizontal (centrifugal) load force. And 2. The rider does something to increase the AoA of the water over the foil and the result is horizontal lift (turning) force.

But what I don't know, is when the rider does the exact same thing, creating the same inputs through his feet, with the same pre-turn front-to-rear weight distribution, then why do some front foils generate a very different turning forces?

The "push back" effect can only happen AFTER an increase in load. In Mark's aeroplane basic theory reminder, if the plane rolls and nothing else changes, then it dives. The aero/hydro plane "push back" reaction cannot happen until after a change in AoA or load.

Imagine two scenarios. One where the rider's centre of mass remains positioned vertically above the board, and he rolls his ankles left-right and feels the hydroplane's "desire" to carve turn-away, before he brings it back. The other, where the rider lets his body pre-fall to the inside of a turn, then uses his feet and rolls the foil over expecting it to turn back under his falling body to hold him up. Why do some foils do this much better than others?

Could it be that (A), the foil is briefly unloaded, by the rider's inputs (feet load), and when the foil load is reduced, then one foil design+flex wants to climb much quicker than another? Would a tendency to climb quickly when unloaded convert to increased AoA for when the load (weight) comes back on??

Or (B), something to do with one foil being able to recover lift more quickly, on the side which briefly rolled upwards and lost some AoA lift during the roll away from flat? Such as something to do with the control of flow of fluid off the tips of the foil during roll changes.

Or perhaps A and B are related and both in effect.

I have two front foils which carve turn beautifully: The naish HA640 (span 810mm) and Naish Kite650 (span 640mm). And another foil (one-piece hydroplane with shorter fuselage) which is very loose in roll, but responds too late with horizontal lift/turning force. This is my Chubanga v1 kite hydroplane with front foil approx 500cm2 and span 620mm. The little Chuba tends to dive and tracks straight when rolled over. It can be put into a decent carve turns, but requires much more rear foot pressure to bring it around. All foil sets offer very good pitch control.

Both the naish foils have substantial AoA twist (end view of the foil) in the tips. The Kite650 is a little more curved thru the middle, and has flattened tips. The HA640 has turned-up tips. Both naish foils have great turn response regardless if mated with a stab foil that is flat or with turned up tips. But the stab with turned up tips does tend to produce turning lift sooner and does connect yaw with roll more intuitively. Great turning on thse naish foils with any mast length 75 to 101cm.

The little 2016 Chuba has almost no tip twist and has turned-down winglets. The 97cm long mast is a work of art, being and beautifully stiff and thin. The Chuba does turn much better (tracked less) now, after I cut off the turned down winglets on the stab foil. Moving the mast+foil fwd in the tracks (vs board+body) certainly helps, but creates bigger problems for me elsewhere.

I want to fix the little Chuba. I have it for fun of going fast. However going fast in fun turns does require some early horizontal turning lift else it's too much hard work. I like work in the shed, but hate hard work when foiling. My thoughts are to rebuild the front foils tips to be more like the naish HA640, or reshape the top of the front foil section to produce more lift (like the HA640), or build upward turning winglets on the stab foil. Or a combination of all three. Then hope it's not significantly slower.