Parawing VMG & Upwind/Downwind ratio - Share your findings!

[J_L]

No, my 780 is my own design, AR 11.6. I was on a 6’10" x 18.5" 95L board with a Tuttle box/mast, so definitely on the efficient end for takeoff.

I tried it today and found the bottom end, it was 13 gusting 17 or so and I came close to getting up but never had a gust that lasted long enough to get fully on foil. I put the PRv2 5.0 up and even with that I had to wait for a puff and pump pretty hard to get up so it was pretty light.

The pump on the Zap is a bit technical, if you just go at it it will start to jellyfish and deflate killing the power. I found a little pull and release on the brakes stabilized it through the pump but still it needs a lighter touch than a good single skin.

[foilstate]

Well actually the calculation is made averaging every second of upwind, excluding the jibes, so it’s just the acceleration part after the jibe that might penalize the total vmg. But definitely doing longer and symmetrical reaches next time

[foilstate]

Thanks! For the angles.. a friend had the same observation. I opted for speed vs angle, but maybe there is a better compromise to be found. I might lack skills and/or something might be penalizing the upwind. I will investigate and try to improve.

As for the wind ranges, I would say hybrid 4.3 (15-25kts), orbit 4.5 (17-27kts), orbit 3.5 (20-30+kts). But the board has a massive impact on the low end. I use a 65L 6’3 18’5" for 80kg, which probably looses 2-3kts of low end compared to 7’ by 80L.

[wrench]

@tommy so sorry, I missed this back in September! I think I found and fixed what was causing the freeze, but let me know if you still have any issues.

[foilstate]

Measuring and comparing parawings in the house while waiting for the wind :

I land on the same AR for each parawing, span (intrados tip to tip on the floor) squared divided by theoretical surface area. Could be due to the arc and/or the way I measured.

Volume wise, 4m zap = two 4.3m hybrids The zap is using a thicker fabric, I sent an email to flysurfer to ask about the fabric specs.

Lines.. Zap on the left, Orbit in the middle, Hybrid on the right. Zap has much thinner and longer lines. The orbit has more and thicker lines which equates to drag..

Water drainage, the zap has few exits. Also double the amount of closed cells, which equates to more internal pressure when up and going. It also has more cells, narrower, again, reduced drag and deformation.

So why would the zap go upwing better than the orbit? Longer lines, more closed trailing edge, more cells, more closed cells, less line drag. And maybe.. thicker fabric holding shape better under load, different airfoil (?), different line configuration (?).

[Kezia]

My two cents:

I’m not particularly good at parawinging, but with my Ozone PR V2, I can achieve around 11–13 km/h (6–7 knots) upwind VMG, depending on the conditions.

I don’t really bother with light winds. Below 20 knots, I prefer using my tow boogie for upwind/downwind runs, as it’s much more efficient. Not to mention I’m riding a 35L prone board rather than a 90L midlength.

A friend who’s better than me can push the same parawing a little further, reaching around 14 km/h VMG. Another friend, who’s a very skilled rider, can get up to 15 km/h with the Ozone Afterburner.

I prefer talking in km/h rather than knots because it makes the numbers easier to relate to actual distances. For example, with a 13 km/h VMG, one hour of upwind riding gives you 13 km of downwind to enjoy.

Another thing: I don’t think comparing upwind and downwind times tells you much, because it depends so heavily on how you like to downwind. I could easily spend 50% more time covering the exact same distance just by slowing down, carving more, waiting for bumps to catch up, or even pumping back upwind to catch another one.

As for foils, higher aspect ratios generally seem to perform better upwind, at least based on my own measurements. But when I want to race, I go SUP downwinding. Parawinging, for me, is all about carving bumps.

Most of the time, I ride a 9 AR foil (KT Nomad 830). Occasionally, I’ll go up to around 11 AR (Atlas 790) when I have a longer upwind leg, so I can enjoy the extra glide on the way back.

As a general rule, for downwind runs under 2 km, I stick with the Nomad. For longer runs, I tend to use the Atlas.

And as I’ve mentioned before, I’m not a fan of the Solus for parawinging. I absolutely love it for SUP downwinding, but for some reason, I just can’t get along with it when parawinging!

[Eriefoiler]

The comfort of VMG is also a factor for me.

PR V2 is a lot when going out well powered and pulling hard upwind, the Orbit feels so easy - I’d be a lot more willing to do a long upwind on it simply because it doesn’t feel like it wants to physically harm me

[J_L]

I get a slightly different span measurement, 3.55m/3.15 AR on the zap.
Draining water hasn’t been an issue, no worse than the hybrid. If you really stuff it and get a ton of water inside, lift it by the trailing edge to dump most of the water out of the LE holes then flip it over and start normally. The small TE vents do take longer than ideal to vent air after a douse, it seems like the TE vents could be designed to be closed with a little brake line tension and full opened with slack lines after dousing. I’m looking forward to your comparison!

I didn’t get a track yesterday but had a great UDW session about 10k up/down. One thing I realized is that while 20% better VMG doesn’t sound like a lot, you stack that with 20% less effort and long upwinders are much less tiring. I finished my run yesterday and felt like I could have easily done it again if I had the time. Normally I do that run and I’m pretty much done for the day.

[wrench]

Android gets some love now too! The beta is open for testing. I’ve put the sign-up and install steps in the Foil Run thread. Would love to hear how it goes on your phone!

foil.run

[Rhirst]

The kite race stance is due to 2 things, massive loads that build from the kite as you accelerate and generate apparent wind. In order to push against the load, the kite is kept as low as possible. Secondly there is alway a risk of a mast ventilation and so if your upper body is bent forwards it is more centered over the board and there is a chance to recover from the ventilation.

[Gonefoiling]

Could anyone examine the caloric consumption of upwinders on single vs double skins?

[Horst_Sergio]

Thank You @foilstate

I didn’t expect the orbit to have a fully? opened trailing edge which is definitely something that creates drag, as more air has to pass also at the inner canopy. I even wondered if maybe those of the ZAP are still too big and was ready to close some for testing. You may try this with your Orbits yourself.

But here is another surprisingly good upwind parawing and also likely the actual biggest modern one used: A converted FS PEAK6 in 8,5 m²

It was never meant for my 62 kg but for a friend with 95 kg. But I was surprised how easy it handles even in 6-9 knts where ZAP does not even fly, but also how well the unfinished trim was already going upwind. I calculated 6,5 knts VMG in just 12 knts of wind! And tacks slightly better than 90°.

To add: I was not riding a super slow pumpfoil but a big DW f-one Eagle 1290 cm² as monofoil as always.

[foilstate]

First sessions on the Zap 4m. Definitely vmg king, will go back to back when conditions allow, but feels like another 20% vmg increase from the orbit Getting close to 45 degrees to the wind, and speed depends on the water surface. Packing is harder but okay, main thing for me is the volume of it packed, a big ball to stuff in the pouch. 17-28kts seems accurate, beyond that it starts creating too much lift. Zero flutter, really hard to get any sort of collapse, really well behaved and fine tuned machine. It feels very solid and rigid, the thicker fabric might have an influence. The apparent wind created is insane, you can cruise through the wind patches without slowing down much.
Got to meet and ride with @Oyvbirk We had an amazing session. Tried his Afterburner 4.3 and was super impressed, performance is somewhere between the hybrid and the zap, it cuts through the wind like a double skin!
Edit : If someone has more info on the afterburner vs other parawings, super keen to hear!

[Matt]

probably been said, but why do the double skins not have the low end of the single skin? Is it just much less effective camber?

Is the ideal quiver a ~4m double skin for 20kn+ all the way up to 40kn, and a ~4m single skin packed in backup should the wind drop much below 20kn?

Also is there any good footage of someone stashing a 4m+ version of any of these (Orbit or Zap) as I haven’t seen a good clip

[J_L]

Sounds like your findings are about the same as mine, how did you find transitions? I haven’t put much time into it as all my sessions have been long up/downs with only a handful of transitions. Standard jibes are not bad, it just took a bit to learn how much brake to apply (a lot) to get it low and turn. I need to spend some time in flat water to figure out tacks and downloops at some point.

[J_L]

I think a lot of it is about pumpability. The Zap has a good amount of static pull but the pump in underpowered conditions is tricky. I think it’s mostly due to the extra weight and also the mass of air inside the wing (rough estimate around an extra 500g) that’s accelerated and needs to recover on each pump. It feels like that extra mass moving around leads to the wing jellyfishing and then deflating after a few pumps. Pulling the brake each pump helps stabilize it quite a bit but I still can’t go flat out pumping like with a good single skin. The Hybrid has similar but less extreme behavior and the brake pull technique helps there as well

[foilstate]

Just jibes for now, quite easy if enough wind. Only thing is the long lines and the wing far in the window can surprise a bit the first few times

[foilstate]

For the quiver, it seems like surface area cannot be cheated with double skin. With a 4m when the wind is above 30kts it doesn’t matter if it’s an afterburner/hybrid/zap, they all max out at a few kts difference.

Footage of stashing I will try to do it.

[Wouzel]

@Matt

but why do the double skins not have the low end of the single skin?

My understanding of them is that ram air designs function with forward movement and apparent wind. When you are trying to get on foil they don’t have the forward drive that comes with the apparent wind. Once on foil tho, the air is “rammed” into the chambers and you can go from feeling like you have almost no power to get on foil to being perfectly powered in an instant.

If you are solid at your paddle up in the bumps, that’s the ideal technique for getting up with double skins IMO. I think of the double skin as having the same pull as my paddle.

@foilstate

With a 4m when the wind is above 30kts it doesn’t matter if it’s an afterburner/hybrid/zap, they all max out at a few kts difference.

The only sail I’ve managed to experience a 20-40+ range on has been the 3.1 LTX. Most fun, least low end worries at 25+ IMO. The Paia 3.1 I experienced 27-47 but it was not fun or impressive until 35 knots.

[FoilMad]

Wow you could get lost in the foil run software.

I uploaded a few of my PRV2 recent session. Not the ones when i was underdone but a few where I was well powered on my 3.6m

I can’t match @J_L with a 7.6 VMG climb on a PRV2 but I did get a few around 7 as below. It seems to me a PRV2 can do 6 consistently with plenty of power and skill. Pushing to 7 is really at its limits for my skill and wave conditions I think. I have segments getting around 8 VMG but it feels really on the edge. I can see on my port side (strong side) the less favorable swell angle knocking my speed down.

I look forward to my 3.6 afterburner and 2.7 orbit arriving very soon and our season just starting.