Hydrofoil virgin

[Peter_Frank]

but the shorter overall fuselage is what makes it faster.

Just to be clear so home builders do not get the wrong ideas.
You mean it turns faster and, or reacts faster to control inputs but certainly NOT speed alone!
All design aspects being the same a shorter fuse does not mean more speed.
Saying one KBHF is faster than another due to fuse length is misleading, all the other factors need to be considered!
Profiles, thicknesses, stiffness and LE, TE shapes are far more important than fuse length although it is a factor.
It would be ashame if a home builder made a shorter fuse thinking it was faster when in fact it is much more sensitive to pitch control, therfore harder to fly.
@ Don C
Yes it seems that the stiffer the strut the better even with maybe more thickness while maintaining a good clean profile.
I got to test fly the exact same factory produced strut, one using normal carbon and the other high mod, the latter has much less twist and flex and flew MUCH better!
R H

Agree fully with RH.

In fact, a shorter fuselage could mean you need bigger control surfaces, and the net drag could be higher than the short fuselage constellation.

Not so simple, and yes, home builders might really get it wrong and make a foil that is (too) difficult to ride.

PF

[revhed]

@hawaii,
I was simply stating that saying one KBHF is faster than another because of a shorter fuse is not taking into account ALL the other much more important design factors.
R H

[Hawaiis]

When you go to a race, do you want a motorcycle or a bus as your weapon of choice?

[Soren Gabriel]

First of all - hanks for a very informative post on wing design.

After a long summer and a lot of fun from testing the Gabriel foil version 1.0 to 1.4 (same T-bar, four different wings) I have ended up deciding to go for generation 2 with a brand new T-bar and a new system for mounting the wing (see mast and fuselage on photo). Check out the project and other DIY foil projects at https://www.facebook.com/groups/danishkitefoilbuilders/.

I am not a complete beginner anymore and for the next season, my goal is to ad speed to my foiling experience – but still without completely losing the stability.

From what I have read in this post, the Alpine foil seems to offer a good compromise between speed and stability. With a relatively long and narrow wing, but still with a big wing area, some twist in the wing, a long fuselage and big stabilizer and fin.

I am planning on a delta shaped front wing with a total length of 68 cm, a chord of 12 cm at the center and 7 cm at the tip. This gives an area just over 600 cm2.
Like the Alpine the distance from wing to wing will be 70 cm and the stab will be about one third of the front wing.

Before I start building the wings I would love to have your comments on seme questions.

How much twist would you make in a wing with a length (center to tip) of 34 cm – and would you distribute the twist evenly along the wing or concentrate it near the tip?

Many commercial brands uses an arrow like wing design (wings with sweep). What difference does it make compared to a delta design?

Most commercial foils seems to be anhedral. Does this give other advantages than yaw stability and reduced risk of getting the wing out of the water?

Greetings Gabriel

[Robsw6]

Great overview - the Aguera sounds like the most relevant foil for an intermediate?

[Don_C]

Great overview - the Aguera sounds like the most relevant foil for an intermediate?

I'd say most relevant for a beginner or intermediate. Good for an advanced rider too but not the fastest out there.

I've just started riding my new Spotz V2. It is really fast and responsive. The transition from the Aguera wasn't bad at all. 6 months on the Aguera really prepared me well for the faster twitchy Spotz.

I'll be keeping both foils. The Spotz for speed and racing. The Aquera for light wind free riding, especially in waves and in marginal light conditions.

[Hawaiis]

Great overview - the Aguera sounds like the most relevant foil for an intermediate?

I'd say most relevant for a beginner or intermediate. Good for an advanced rider too but not the fastest out there.

I've just started riding my new Spotz V2. It is really fast and responsive. The transition from the Aguera wasn't bad at all. 6 months on the Aguera really prepared me well for the faster twitchy Spotz.

I'll be keeping both foils. The Spotz for speed and racing. The Aquera for light wind free riding, especially in waves and in marginal light conditions.

So proves my point, shorter fuselage is faster.

[evan]

Best example for short VS long Fuse is Levitaz, they are experimenting with an even longer Fuse so that the aft wing can be half the size. Overall reducing the drag more than gained by the longer Fuse. All the other components stay the same.

[ronnie]

I measured the foils in this photo:

Foils Top View (Medium).jpg

From left to right: Spotz1 2013, Aguera 2014, Alpine 2014, Carafino Race 2014

Here are the approximate measurements. We did not do an accurate measurement since the discussion is about factors affecting ease of ride, not design specs.

Foil Measurements.jpg

My comments/opinions as posted earlier:

The Spotz1 with high aspect wings is really fast, but with the short fuselage length, and medium wingspan, it is not so stable for learning. Beginners find this one a little more difficult. It does turn like an F1 race car, extremely responsive, and is great once you have some experience.

The Aguera is the one I learned on. It has high aspect wings like the Spotz1, with similar wingspan, but the fuselage is much longer. It is super easy to ride, in part, due to the stability from the fuselage length, and wing to stabilizer length. It turns much faster than the Alpine but not quite as fast as the Spotz1. It has good speed upwind and downwind. The beginners I've had try this foil really like it for ease of use.

The Alpine has fairly high aspect wings, very long fuselage length and very wide wingspan. It is super easy to ride due to the stability. It does not respond quickly in turns compared to the Spotz1 or Aguera. The beginners who rode it on our test day really liked it.

The Carafino has a low aspect wing and is easy to get up on. Many beginners in our area have had a good learning experience on these. They are relatively slow but tend to have a loose feel going downwind.


Here is a photo showing strut angles. I don't really know that the angles make much of a difference to ease of use and learning, but it is interesting to see the differences.

Foil Struts (Medium).jpg

Note that some foils have fins for yaw stability, like the Spotz1 and the Alpine. The Aguera seems to accomplish this through the wing and stabilizer extensions and a flair at the lower end of the strut where it attaches to the fuselage.

Foil Fins (Medium).jpg

I personally don't like fins after seeing some damaged from hitting bottom.

So, there's some information on the foils. The boards they are attached to are all different. When learning, board shape can be a factor. But that's a whole other topic.

Hi Don,

Is that the Aguera All Around front wing or the Race?

[adri_levi]

Hi Levitaz just released this Freeride/Beginner Foil called Element.

Maybe this is something for you?
I think its really eays to ride and you can easily upgrade to the Freerace/Race Setup by changing the Frontwing. Of course my opinion is not completly neutral

http://levitaz.com/