Author Topic: Foot placement over mast.  (Read 7342 times)

PonoBill

  • Cortez Bank Status
  • *****
  • Posts: 25864
    • View Profile
Re: Foot placement over mast.
« Reply #15 on: February 16, 2023, 09:37:05 PM »
I'm considering drilling out the Axis base plate if necessary to give me an extra inch in the tracks. It seems easy enough to do since the threaded holes are already there. What are those threaded holes for anyway? Does anyone know?
I never did ask why they were threaded (which never made any sense to me either), but I did receive a new baseplate a few months back, and was happy to see that the holes were no longer threaded, and that an 8mm bolt slipped right on through.



Now we just need to talk them into countersinking the holes before anodizing. I've countersunk mine, but now they are bare aluminum.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Admin

  • Administrator
  • Cortez Bank Status
  • *****
  • Posts: 6443
    • View Profile
    • StandUpZone
    • Email
Re: Foot placement over mast.
« Reply #16 on: February 17, 2023, 03:21:07 AM »
I can't tell whether you are all in agreement or disagreement at this point.

BUT that eCalc website is awesome and it helped define a few things.

1st off - The Aerodynamic Center of lift is at the 1/4 chord, or 25% back from the leading edge.  Google it.  No ambiguity.  I think Adriaan Roper once said it was at the 1/3 chord, BUT this is where the rule of thumb(s) start.

I replicated the design of my new favorite Axis 1300 wing (this is probably worth another post) and it calculates the CG should be 5.3 cm back from the leading edge with an 18 cm root chord.  This DOES work out to ~ 1/3  :o but this is because of the wing sweep.  The 1/4 chord point moves steadily back as the wing sweeps making the AVERAGE 1/4 chord further back from the dead center leading edge of the wing.  Hence why this software is great. Add some downforce from the tail and this would move the requisite CG forward.  But likely between 0 cm (leading edge of foil) and 5 cm.  ~ 2 inches of play.

That would be the center of the stance.  Go WIDE for beginner (maybe 26" or 13" forward, 13" back) and narrower for expert or downwind.


Probably no agreement yet :).  The image Don't had psoted earlier shows the Center significantly futher forward than actual.   Centers  move greatly depending on foil design.  Have a look here and check some of the cambered foils.  http://airfoiltools.com/search/list?page=a&no=0 . Look at the max thickness points given as a percentage.  These shapes individually will define the centers.  Adrian is basically telling you that he is using sections with the max thickness a bit futher aft (which he is, although that is only one factor).  So does Go Foil.  The 25% rule is not great for our sports.  Even so, that is not the big issue.  That will set you off a little, but other elements such as sweep and margin will set you way off.  As a side note AC is really cool becuase it remains constant as angle of attack changes.  That is really cool to consider and was very illuminating for me.
« Last Edit: February 17, 2023, 03:36:40 AM by Admin »

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #17 on: February 17, 2023, 05:46:32 AM »
So, we can agree that the Center of Lift is somewhere in the range of 1/4 to 1/3 of the chord back from the leading edge. Since my base plate has reached the forward end of the tracks, I'm kind of rooting for 1/3 because that would move my center of stance back an extra 5/8".

-
« Last Edit: February 17, 2023, 06:13:09 AM by Badger »
Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

Admin

  • Administrator
  • Cortez Bank Status
  • *****
  • Posts: 6443
    • View Profile
    • StandUpZone
    • Email
Re: Foot placement over mast.
« Reply #18 on: February 17, 2023, 06:41:29 AM »
So, we can agree that the Center of Lift is somewhere in the range of 1/4 to 1/3 of the chord back from the leading edge. Since my base plate has reached the forward end of the tracks, I'm kind of rooting for 1/3 because that would move my center of stance back an extra 5/8".

-

No.  It will be in that range at the very center of the foil only (considering the front wing only - which is also an error).  But that will move back on all swept foils (all of our foils are swept) and will move back drastically on many.  This should never be used. 

PS, Keep in mind that center of pressure / center of lift moves with changes to angle of attack. Aerodynamic center does not move and both need to considered with Center of Gravity.  There are no useful rules of thumb here.
« Last Edit: February 17, 2023, 06:59:58 AM by Admin »

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #19 on: February 19, 2023, 05:39:53 AM »
Now we just need to talk them into countersinking the holes before anodizing. I've countersunk mine, but now they are bare aluminum.

How necessary is countersinking? Would pan-head screws not hold as well?

-
« Last Edit: February 19, 2023, 05:44:02 AM by Badger »
Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #20 on: February 19, 2023, 01:34:34 PM »
If my mast plate is all the way forward in the tracks and I find that I still don't have enough front foot pressure, would adding a mast plate shim help?
If I'm understanding you correctly, if you have too much lift from your wing and mast position (...don't have enough front foot pressure), you need to move your mast rearward to take out lift, before adding any shims to your mast or rear tail.

Edit: If I read that wrong, and you meant that you don't have enough lift in order to use your front foot to pressure the nose of the board down for better pitch control of the board/foil throughout your runs...then yes, if you're all the way forward, you could start by shimming the stab so from level, the trailing edge is higher than the leading edge.

I'd try that before starting to trim the baseplate, which more or less just changes the ride level of the board when the foil is riding flat/level, and doesn't change the overall riding lifting characteristics of the foil as shimming the tail does.

The +1 degree stab shim seemed to do the trick. It added just enough lift and front foot pressure to equalize my feet. Today my pitch control was much more solid.

I was using the BSC 1060 with the 400 rear. It will require more time on the board to confirm but I might be okay now with the base plate all the way forward at the end of the tracks.

-

« Last Edit: February 19, 2023, 01:41:30 PM by Badger »
Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

PonoBill

  • Cortez Bank Status
  • *****
  • Posts: 25864
    • View Profile
Re: Foot placement over mast.
« Reply #21 on: February 20, 2023, 10:15:29 AM »
Now we just need to talk them into countersinking the holes before anodizing. I've countersunk mine, but now they are bare aluminum.
How necessary is countersinking? Would pan-head screws not hold as well?

I dress like I"m homeless but I'm fussy when it comes to mechanical stuff. Panheads sticking up are unbearably gauche when you have enough material to countersink flush. On the other hand, I love round-headed rivets in Aluminum. It's all about style.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #22 on: February 20, 2023, 12:13:30 PM »
Now we just need to talk them into countersinking the holes before anodizing. I've countersunk mine, but now they are bare aluminum.
How necessary is countersinking? Would pan-head screws not hold as well?

I dress like I"m homeless but I'm fussy when it comes to mechanical stuff. Panheads sticking up are unbearably gauche when you have enough material to countersink flush. On the other hand, I love round-headed rivets in Aluminum. It's all about style.

Thanks, I'm the same way. If I have to do it, I want it to look good and it might as well be flush.  8)

I'm thinking a light coating of Tef-Gel should protect the bare finish.


Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

Califoilia

  • Axis Demo Rep
  • Teahupoo Status
  • ******
  • Posts: 1510
  • San Clemente
    • View Profile
    • Email
Re: Foot placement over mast.
« Reply #23 on: February 20, 2023, 10:08:09 PM »
The +1 degree stab shim seemed to do the trick. It added just enough lift and front foot pressure to equalize my feet. Today my pitch control was much more solid.

I was using the BSC 1060 with the 400 rear. It will require more time on the board to confirm but I might be okay now with the base plate all the way forward at the end of the tracks.
Great to hear! If you ever get a chance, try one of the new Progressive tails (if that "400 rear" is an older Freeride or Flat Speed).

I've found that they're something special with lift, speed, and control. So much so that some of the larger HPS wings (980 and 1050) hat I wasn't a fan of earlier, all of a sudden came alive, and are so much fun with the 350 and 325 Progressives.
Me: 6'1"/185...(2) 5'1" Kings Foil/Wing Boards...7'10 Kings DW Board...9'6" Bob Pearson "Laird Noserider"...14' Lahui Kai "Manta"...8'0" WaveStorm if/when the proning urges still hit.

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #24 on: March 02, 2023, 10:12:50 AM »
Countersinking the Axis holes was easy. They came out perfect. Now I can move the mast forward an extra inch if I need to.

I might be okay using the slotted holes but it's nice to know I can go beyond that if I want to. I doubt I would need more than a quarter to half an inch max. Psyched for more E3 testing on Sunday.
Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #25 on: March 05, 2023, 01:38:31 PM »
I had a three-hour flatwater session today in better conditions and really got to dial in the board and foil. It turns out that the foil doesn't need to be all the way forward in the tracks. I was able to bring it back 3/4 of an inch to get a balanced foot pressure. What a relief it is to know I have some room for adjustment within the tracks.

I'll be posting a review of the Kalama soon. I'm very happy with it.
Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

Badger

  • Cortez Bank Status
  • *****
  • Posts: 2662
  • Seacoast NH
    • View Profile
Re: Foot placement over mast.
« Reply #26 on: March 07, 2023, 12:15:35 PM »
Unlike the Naish board, the new Kalama requires the Axis mast plate to be all the way forward for equal foot pressure. I'm using a single extra-long front foot strap set all the way forward.

Strap all the way forward? try moving front strap back, you're on a SUP you should have room to play around a bit. bring your front foot closer to foil if you can't bring foil closer to front foot

Thanks for the suggestion. I moved the strap back one screw hole and it definitely helped smooth the pitching.


Kalama E3 6'1 x 23" 105L
Axis HPS 980 / PNG 1300
Sunova Flow  8'10 X 31"  119L
Me - 6'0" - 165lbs - 66yo

 


SimplePortal 2.3.7 © 2008-2024, SimplePortal