SF, Do you remember the number series you used for your NACA foils (4???). Just curious.
I have a NACA foil graphics generating program I picked up off the internet years ago for free that I play with.
metal into fcs tabs , do you think it would be doable ?
if so , four back plugs could do the job in existing boards , so you can move the foil forward far enough , as needed . [?or maybe even , five? ... I remember that my brother Simon had that many in one of HIS boards once ...I ' think because it was a bit thin tailed for a box , perhaps ? ]
I'm curious ...
was it because of the SIZE of the foil['s head] , that you settled on the measurement of "12" up from the tail " ?
ie : -
with a smaller area [or shape?] foil 'head' , would you then [be able to / want / need to ] move it closer to the tail ?
IS that 12 inches up , to the back of the base of the strut , or to the back of the foil 'head' [is that what you call a flat bit on a foil ? or a "wing" ? I have no idea ...!!]
and , when you use the word "chord" for a foil ...
.....is that to the [?back of ? the ] flat [head] area measurement ,
or is it measured from the base to the tip of the strut only .... measured at 90 degrees from the board , are we talking?
lastly [for now , anyway !]
......is there much RAKE on the "strut " of the foil ? I ask , because I wonder what effect rake versus an UPRIGHT "strut" actually would have , anyway ? [ on a thing that is basically OUT of the water , yeah ?!]
questions , SO many questions !! ....
cheers
surfboards-curious ben
The strut doesn’t have to be metal (carbon +?, other?). The base of the fin box or strut will probably need to be modified/re-inforced so it can bear the weight of the rider without being pushed through foam and deck.
Chord is the greatest distance from the leading edge of the foil to trailing edge looking at the cross-section.
Ben, I think it will end up without athe top of the foil wil tabs to a video just for you Ben, the wave starts out until it was just a ria 26 lifts even or Sydney or struts.
[IMG]http://
a worthy inovation.
kudos.
…ambrose…
sending a link
to morey?
Thanks Ambrose for the compliment !
Everyone can see its a derivative of the Laird Experience, but at the same time there’s a twist so its applicable to standard wave catching techniques and locations. It’s an alternative every surfer could easily use.
Not totally new but a new way to enjoy the power of the waves and the sensation of flight without the jet ski for the tow-in.
Ive put in an application with Kickstarters Australian equivalent hoping to get this project finished sooner rather than later, so with a bit of funding I could have it finished this year and with a short movie of ‘the journey’, and a small run of surf foils to give to the backers.
See what happens.
All the flat horizontal foils were working well.
Predictable control, plenty of lift. With the flat foil it’s always completely submerged so as the power increases the wetted area stays the same and it locks into the building power and gets faster and faster.
So I thought I’d try angling the foils so as the power increases, the foils rise and the wetted surface is reduced therefore regulating the speed/power.
I put the angled foils on today.
Take off… Bottom turn…
…easy…
Pull in to a shoulder high tube…
…all good…
Then BAMM !!!
Too much area ! Too much power ! I tried to repair it but its easier to build again.
The horizontal foil had an area of 250 sq in
I figured the angled foils would need more area so they are 352 sq in in total at 30 degrees
Now back down to 180 sq in with a thinner angled Vee setup at 45 degrees.
Its not important that people comprehend the figures or follow the science, it’s more a journal of the evolutionary construction.
Seems like the struts should be made of thicker plate.
What’s wrong with flat and faster? Fast sounds good to me.
Props for pushing the envelope!
Suggestion: for less drag and ventilation, maybe you could set the nuts in epoxy in holes in the foils, and/or use flat head screws, grind off any projecting screw shaft…
Simpler alternative, test if it’s better to have the “bumps” on the bottom (high pressure side) instead of the top, where they probably contribute to ventilation. My hunch is bumps on high presssure side of foil could be better.
Maybe you did already, probably you’re miles ahead - just having fun thinking alongside your experiments here…
Thicker struts or cold-molded foils faired into strut/bases might help I guesss too ? ?
Keep up the good work!!
.
[quote="$1"]
Seems like the struts should be made of thicker plate.
What's wrong with flat and faster? Fast sounds good to me.
[/quote]
Sure fast is good but this is out of control because its tapping in to the power within the wave and its too strong in the tube.
Currently theres a horizontal area of 250 sq inches and a vertical area of the struts thats 66 sq in.
But Im trying to minimise the struts because of the weight and safety.
And add a foil that varies its wetted surface in response to increased speed.
SO less strut, more controllable foil.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/2013/3.jpg[/IMG]
And hopefully refine it so it only needs one strut.
BWD, Funny thing about all the bolts and hardware, it still doesnt stop the foil from charging, but I'll definately smooth everything out later on to maximise the lift and speed. Good idea about reversing the foil too !
My logic on the triple foil setup is that by leaning – forward, backward, side-to-side or level – you change the amount foil surface area in the water. Improve turning etc. Spread out the planing surface for more stability too.
I like the triple foil idea, might be possible to have them at different depths / heights ?
Here is how this has been done by others:
http://www.ahd-boards.com/models/afs-1/en
and a very cool vid:
http://www.youtube.com/watch?v=fZb6OSyLgmQ
all the best
Asymmetric depths? Interesting. Which foils where?
Would be interesting to test. I’m thinking that might cause a porpoising (repeating up and down) effect.
Well I just meant flip the bolts/screws so the nut projecting was on the “bottom” leaving the low pressure upper surface smooth.
For dealing with speed, you could try a foil with a different plan form, ie curved, (maybe hollow curve) leading or trailing edge, to get a more rapidly diminishing foil area as the foil rises.
Common problem foiling in boats is when you are going fast, the foil makes too much lift, breaks out and ventilates. So foils built for speed are smaller, butfor low speed/takeoff you need bigger ones…
Experimenting you can find the best planform/angle combination …
I’m fascinated by the whole foil concept. Makes so much sense to get all the drag of the board out of the water, but most of the ones I’ve seen have the rider balancing on a single foil with one strut. That seems like riding a unicyle compared to riding a bicycle.
I like this approach of 2 foils for a stable platform:
http://www.youtube.com/watch?v=4Tst5dTveO8
Surffoils, what about splitting your foils area into 2 smaller struts fore and aft? Keep the same reduced chord approach just split it into 2 foils so you’re not having to balance and it’d also split the load in half so each foil wouldn’t need to support as much weight.
Just throwing some random thougths out there.
I love the fact that you are taking the empirical approach to this and just riding and refining based on real-time feedback. Thanks for sharing!
edit:
Just stumbled across this Navy video on foils, pretty interesting - http://www.youtube.com/watch?v=3Gy1SIWiQpc
Hi GrThis video reminds of why I wouldnt do seperated http://www.youtube.com/watch?v=4Tst5dTveO8
Surface piercing marine foils have a history of using a Vee
Just for a laff, I’ll do a ventilated flat foil first.
And then an XXXL Wing keel fin.
Just to see what happens.
Vacbagged 4 layers of 6 oz both sides…
Estimated reduction of area of 20% So hopefully it will still foil at a minimum speed but will have less resistance against the sharply rising water in the tube. Btw, this foil is not a serious attempt, more of a science project.
, it was as fast to the nex one is an [IMG]http://