Why isn't there a huge single skin?

[Da Yoda]

It's not a single skin nor a kite, but it's over 21m. Think of it as "half" a kite.
Here's some info about the technology. Go to 2:20 to see a real-life prototype dinghy


Imagine this as a kite. All you would need is one and you'd simply adjust the size to your preference or conditions.
Coming available in June, 2100

[Oldman_Dave]

I had the 13m p4 as well. While it was the most stable rock steady kite in anything from 2kts upwards on the beach, it wasn't the best when moving on a foil. Mine suffered random and fairly serious tip curls (both top and bottom) when just motoring along, next thing you were fighting to get the kite to resume it's shape before it balled up and hit the water. I think the worst issue though is that you only have support from the structure from one source - line tension making the bridle work. So gybes were super hazardous, take your eye off the ball for a second and shoot a few metres downwind, and suddenly you have a shapeless sheet falling out of the sky. With a twin skin or LEI you can still have the same light wind gybe issue, but if you slack the lines the kite will still hold some shape, which gives you a good chance of catching it.

[PullStrings]

With 21 wide quad surfb I was using the Flys connect bar on the 13m peak 4

I experimented with various line lengths in 9-13kn

First 3 sessions with the longest lines supplied
14m + ext 7m then add bridle @5m = 26m approx
Worst upwind performance...ha ha

Next 2 sessions took the 7m off = approx 19m
Best at going upwind but still not easy going
Plus power stroke was so short for that slow/large single skin

I had with me 3m ext
So for next 2 sessions I tried that
Now at 22m
To me that was the ideal compromise
Power stroke felt good
Trying to go upwind was still fairly poor but more enjoyable
Could keep the kite sheeted in more than when running the lines at full length reducing fluttering and the kite was going visibly higher in the window

Still not the kite for what I like to do
Was not mine
Was doing R&D for a friend who bought it
After my report he ended up selling it without ever trying it
13m did however feel good going off the wind on some smallish 3ft waves in 10-12 kn of wind
Drifts effortlessly
Just floats up there as you ride

[edt]

really great answers thanks guys!

[fernmanus]

I have a 13m Peak 4. I have only used it snow kiting, never on the water. I find it is less versatile than a double skin kite. It has less range. It will glide if there is enough wind. Overall, I would much rather fly a Soul 12m.

All of that being said, why should the future of large single skin kites be determined by one kite? I had a 16m Flysurfer Mast Air. The performance of the 13m Peak 4 is better than that old Mast Air. The Mast Air pulled like a truck, but due to a limited range, it usually was pulling you down wind like a truck.

Bottom line is double skin kites have come a long way. If the same effort was made to improve large single skin kites, we might all be surprised by what develops. However, if designers don’t try, well it may be a very long time before any break-throughs occur.

[PugetSoundKiter]

Why isn't there a huge single skin?

This looks huge

[Peter_Frank]

I have to comment on what so many are saying:

Small windrange, and bad upwind.

Upwind is never a problem on a hydrofoil, and these kites are not really meant for anything else IMO, apart from snow.

Also, in winds where big sizes are used say 5-7 knots, the wind is usually extremely stable (sea breeze winds in many places) so you dont need range, and also I believe all kiters will rig down if wind should pick up.
Here the advantage of a non-air-filled single skin is great, you can just land the kite and pack it down immediately, not waste time on pressing air out.
Big lulls can be a more common thing in superlight winds - and here these kites excel.

Strutless LEI kites have a bit of the same characteristics regarding windrange, great low end and hangs in less than rideable, but small range.

Thus I understand why there are many who like the bigger single skin kites.

Of course, for non-hydrofoils or for jumping, they are not the thing to choose.

My main point though, is that the windrange and upwind is not an issue for most hydrofoil riders, with a big single skin kite, so would never be my reason for not choosing such one.
Too low peak power could be my reason though - but the low price on most, and superfast and small packing, is of course appealing.

Peter

[tallakt]

There is the issue with how much power would you need and the apparent wind speed and direction.

How much power do you need? In my experience you dont need a large kite to get to planing on a hydrofoil. The practical size limit seems much less than 21 sqm. A bigger kite is difficult to handle, costs more and turns slower.

Say you are riding slow at 15 km/h (8 knot) at 4 knot wind, directly cross wind. The apparent wind direction will face atan(8/4)=63 degrees against your riding direction relative to the real wind. That means in order to gain upwind on your tacks the hydrofoil and kite must be more than 27 degrees efficient (in quasi science terms). This would be no problem if the hydrofoil mast was aligned horizontally, but it does have to be aligned more vertically to support your weight.

Also you need to handle the kite swimming 4 knot wind and riding apparent wind 9 knots, giving lift ratio of 5x as lift is airspeed squared. So the kite needs huge depower to be useful.

Net result is that kiting in these conditions require a super efficient, maybe oversized hydrofoil, a really efficient kite with a huge aspect ratio, slow riding speed etc. Probably just not worth it for most.

[Atte]

I had the 13m p4 as well. While it was the most stable rock steady kite in anything from 2kts upwards on the beach, it wasn't the best when moving on a foil. Mine suffered random and fairly serious tip curls (both top and bottom) when just motoring along, next thing you were fighting to get the kite to resume it's shape before it balled up and hit the water. I think the worst issue though is that you only have support from the structure from one source - line tension making the bridle work. So gybes were super hazardous, take your eye off the ball for a second and shoot a few metres downwind, and suddenly you have a shapeless sheet falling out of the sky. With a twin skin or LEI you can still have the same light wind gybe issue, but if you slack the lines the kite will still hold some shape, which gives you a good chance of catching it.

the reson you had problem with your gybes was because your kite was not tuned correctly, my 13m did tip tuck a little before but I fixed it, so now I can slack my lines completely when gybing without the kite tip tuck or worst case end up like a ball. There is a post in the long peak 4 tread that describes how you fix the tip tucking, very easy to do.

[bitxopalo]

....Net result is that kiting in these conditions require a super efficient, maybe oversized hydrofoil, a really efficient kite with a huge aspect ratio, slow riding speed etc. Probably just not worth it for most.

interesting maths! , really I struggle bellow 5knt.

Average winds here is arround 5-6 knot all winter here. So I managed to survive in such conditions. I tried the peak 11 with no satisfactory results (just doable) so I change to a 12m doubleskin and is actually more fun.

I am using a low AR kite and 1100 surf foil (gong curve)
But I am light 65KG... My opinion is that weight is part of the game.... Speed is so low that super efficient gear does not make significative difference.... IMO