I picked up a used 'china rip off' all carbon surf foil (based on the lift foil template) just for pure curiosity to play around on a prone board-have sup foiling down. The rear wing fits seamlessly facing down but I had always assumed the rear wing goes up - which I did manage to fit it facing up with some new screws...although not quite as neat alignment.

80% of the pics I looked at online has the front wing down/rear wing up BUT there was a couple with the rear wing down.

Any thoughts?

Nice rug..

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DavidJohn said..
Nice rug..

Ha! Yes. It does have that 'keys in the bowl/swingers club's vibe.

Suits the man shed well.....

Whichever way means the rear wing pushes down.

Try it and see. If you can't tell then it doesn't matter.

I have Naish foils and stab is tip down.
I did try it tips up to minimize contact with the bottom but was a no go so tips down for Naish SUP foils.
Some are up and some are down.

If it fits seamlessly with tips down then that is probably the way it is designed to go.

Heaps of foils do.

Thanks folks....so maybe it is rear wing down after all. As it's a lift foil 'rip off', I checked the lift foil profile and their rear wing is definitely up.....but if u guyscare calling wings down is really not that strange then I'll indeed run it both ways.

Anyone savvy with the 'rear wings up vs. down' hydrodynamics? Or is it really like a box of chocolates..to use forest gump analogy...

Put a level on the rear wing. Figure out which way it's creating lift downward. Then you got it right.

1mm aoa makes a huge difference.
The test is where you need to put your back leg for lift off and comfort on the fly.
If to far one way or the other for your comfort stance then adjust aoa.
Works for me.

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foilSURFmachines said..
Put a level on the rear wing. Figure out which way it's creating lift downward. Then you got it right.

Thanks fSm for that suggestion. I may be a bit special but Im not sure what you mean....

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warwickl said..
1mm aoa makes a huge difference.
The test is where you need to put your back leg for lift off and comfort on the fly.
If to far one way or the other for your comfort stance then adjust aoa.
Works for me.

And thanks warwickl. What does the "aoa" acronym mean? Also, back foot usually doesn't move - once up? Im not sure what you mean....again, I may be a bit special....

The more I think about it twists my mind that you can have foils with rear wing up and some with rear wing down....fair enough there are some that are flat....but complete opposite?

Not seen any airplanes with a rear wing down as yet......is there a hydrodynamic nerd in the house? That can pitch at dummy level....

The rear stab on a foil should have some small amount of angle to it that makes it want to move downward When travelling through the water. This in turn makes the front wing want to go upward. (A upward AOA... angle of attack)

So do like FoilSupMachine says it should help you find the correct way for your foil.

AOA angle of attack. You might want to look this up...

Thanks fishdude. So, if I'm understanding correctly, a rear wing must create a downward force to cause the opposite effect at the front wing..ie lift. The rear wing therefore can be facing up or down/mounted top or bottom BUT it's design will vary to create that same 'downward' force....

And angle of attack refers to the foil in relation to the wave angle/flow of water....I think....

90% of the foils I have seen have the rear stabilizer wing pointing down.

2018 foils seemed to be majority rear wing up.....now 2019 is looking rear wing down....fair call?