Contact   Imprint   Advertising   Guidelines

Holes in aluminum mast

A forum dedicated to Hydrofoil riders


pj sofine
Very Frequent Poster
Posts: 749
Joined: Thu Jun 16, 2011 2:21 am
Kiting since: 2001
Style: silly
Gear: naish torch 12m,9m,epic renegade 6m,9m,screamer 12m. ug styx, skillet
Brand Affiliation: None

Re: Holes in aluminum mast

Postby pj sofine » Wed Sep 05, 2018 1:54 am

DAnderson wrote:
Tue Sep 04, 2018 8:14 pm
pj sofine wrote:
Mon Sep 03, 2018 3:08 pm
Maybe Ill experiment on the fuselage.
I've seen alloy fuselage bent as well fyi
Ok forget it,I'll move on to another worthless endeavor! :roll:

User avatar
tegirinenashi
Very Frequent Poster
Posts: 575
Joined: Wed Aug 27, 2014 3:29 am
Kiting since: 2003
Local Beach: 3rd Ave
Gear: Bates 4000, Dominator MX-10
Brand Affiliation: None

Re: Holes in aluminum mast

Postby tegirinenashi » Wed Sep 05, 2018 5:00 am

DAnderson wrote:
Tue Sep 04, 2018 8:14 pm
I've seen alloy fuselage bent as well fyi
I doubt it. First of all, it is all about the leverage: it is easy to bend a bar when you have 95 cm of leverage -- the full sized mast. It is harder to bend 65 cm one, but as Gunnar demonstrated, still quite possible. Compare it to fuselage, you have perhaps 20 cm to the front wing, and perhaps 50 cm to the stabilizer. At first sight, bending the tail section of the fuse looks probable. I'd suggest, however, that if you hit the reef with the stab but not the front wing, then you are so unlucky that you'd better quit foiling to avoid future serious accident.

Also, what is the mast thickness, 14-15 mm? Compare it to fuselage, which is at least twice as thick. Keep in mind, that competent designer would shape the tail section of fuselage tapered, so that the bend force momentum would be kept approximately constant along the fuselage length. Speaking of tapered fuselage tail section, it is good for hydrodynamics as well.

User avatar
purdyd
Very Frequent Poster
Posts: 1012
Joined: Mon Jan 06, 2003 1:00 am

Re: Holes in aluminum mast

Postby purdyd » Wed Sep 05, 2018 12:39 pm

tegirinenashi wrote:
Wed Sep 05, 2018 5:00 am
DAnderson wrote:
Tue Sep 04, 2018 8:14 pm
I've seen alloy fuselage bent as well fyi
I doubt it. First of all, it is all about the leverage: it is easy to bend a bar when you have 95 cm of leverage -- the full sized mast. It is harder to bend 65 cm one, but as Gunnar demonstrated, still quite possible. Compare it to fuselage, you have perhaps 20 cm to the front wing, and perhaps 50 cm to the stabilizer. At first sight, bending the tail section of the fuse looks probable. I'd suggest, however, that if you hit the reef with the stab but not the front wing, then you are so unlucky that you'd better quit foiling to avoid future serious accident.
goto the ocean someday and lose your board in a wave, or heaven forbid drop your foil board
Also, what is the mast thickness, 14-15 mm? Compare it to fuselage, which is at least twice as thick. Keep in mind, that competent designer would shape the tail section of fuselage tapered, so that the bend force momentum would be kept approximately constant along the fuselage length. Speaking of tapered fuselage tail section, it is good for hydrodynamics as well.
if bending moment was the only design criteria, that might make sense

but you also have to make sure you have enough material for screws to go through and still have strength around the holes

and since you bolt through the fuselage, making it solid makes it impossible to crush from the bolts or an impact

also you have torsional loading on the fuselage so if you were to taper it, it would not be as stiff in torsion

you could make it hollow and increase the size of the fuselage and make it lighter, like oversized tubing on bikes

now it is larger and probably has more drag as a result, hollow means it could leak, and you have that whole crushing problem again

you also have to manufacture the thing and make it somewhat reasonable to purchase

you also have to compete with carbon

BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Re: Holes in aluminum mast

Postby BWD » Wed Sep 05, 2018 1:54 pm

Al fuselages can bend, hollow or solid.
Pretty light tubing from mast to stab could work, but need careful reinforcement, and end up costing too close to carbon but still weaker. Near mast and main wing solid is better, obviously.
Heavier gauge pipe for a fuselage could work but not have a great finish so need finishing work, and some reinforcement etc. weight saving minimal, cost significant.
Well sahaped solid aluminum works -zeeko, Moses, alpine etc. use it.

Do levitaz fuselages bend? Or just fire 5.56 rifle bullets (trick question, they’re solid too).

Carbon is nice strong and light and can be a good shape...

User avatar
tautologies
Very Frequent Poster
Posts: 10096
Joined: Mon Feb 16, 2004 5:36 am
Kiting since: 0
Brand Affiliation: None
Location: Oahu
Contact:

Re: Holes in aluminum mast

Postby tautologies » Wed Sep 05, 2018 6:25 pm

Isn't discussing marginal weight changes on foils kind of useless for most of us?

I mean I get if the foil is lighter it will be a tad easier to maneuver, but the gain is marginal right? The actual weight to consider is total weight between board, foil and human on top. Or maybe I am missing what we are trying to gain?

It's kind of like the guy who spends an extra $4K on a road bike to shed 1lb, but is still 2olb over-weight?

User avatar
tautologies
Very Frequent Poster
Posts: 10096
Joined: Mon Feb 16, 2004 5:36 am
Kiting since: 0
Brand Affiliation: None
Location: Oahu
Contact:

Re: Holes in aluminum mast

Postby tautologies » Wed Sep 05, 2018 6:32 pm

gmb13 wrote:
Mon Sep 03, 2018 9:38 am
This is what happens when you underestimate the forces on the mast when you design foils.
--
Gunnar
Hey Gunnar, how did this happen? Does using a tuttle box put more stress on the mast than a plate?

3InletsWindsports
Frequent Poster
Posts: 345
Joined: Wed Nov 18, 2015 7:52 am
Kiting since: 2001
Local Beach: Shallow Inlet, Corner Inlet, Andersons inlet.
Favorite Beaches: Shallow Inlet, Point Danger.
Style: freeride
Gear: Zeeko
Brand Affiliation: Zeeko importer in Australia

Re: Holes in aluminum mast

Postby 3InletsWindsports » Wed Sep 05, 2018 9:04 pm

tautologies wrote:
Wed Sep 05, 2018 6:32 pm
gmb13 wrote:
Mon Sep 03, 2018 9:38 am
This is what happens when you underestimate the forces on the mast when you design foils.
--
Gunnar
Hey Gunnar, how did this happen? Does using a tuttle box put more stress on the mast than a plate?
The actual load point is right where the Tuttle mount stops an mast is free.
In side load this is almost a knife edge force point and will first start to crush/crease outer skin of mast then off to oblivion

Plates are usually fixed with bolts that in a good design go a long way into mast and take and spread the loading.
Mount plates with collars need to ensure the bolt lengths are down past the depth of the collar.
While the collar can add some strength, relying on it too much from a design point is hazardous.

User avatar
downunder
Very Frequent Poster
Posts: 1520
Joined: Mon Jul 01, 2013 7:16 am
Kiting since: 1970
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia

Re: Holes in aluminum mast

Postby downunder » Wed Sep 05, 2018 9:48 pm

That happened simply coz the alu wall thickness was not near enough. Plus, the bolts alu probably ended right on that spot.

If they protruded the bolt alu a bit further, it would be ok I guess.

Simple design flaw.

PS

For sure a fuse bends, Levitaz bends as hell...

User avatar
tautologies
Very Frequent Poster
Posts: 10096
Joined: Mon Feb 16, 2004 5:36 am
Kiting since: 0
Brand Affiliation: None
Location: Oahu
Contact:

Re: Holes in aluminum mast

Postby tautologies » Wed Sep 05, 2018 10:21 pm

Thx for the rply. It makes sense for sure. I got a Raceboard since it has a tuttle box I am considering adding a tuttle converter to my existing foil.

BWD
Very Frequent Poster
Posts: 3393
Joined: Thu Jun 05, 2003 3:37 am

Re: Holes in aluminum mast

Postby BWD » Wed Sep 05, 2018 11:21 pm

Isn't discussing marginal weight changes on foils kind of useless for most of us?
If you are sticking with a maker/foil set that is coming in at 3.5-4.5kg (ie: the major kite brands) it may be pointless. A 3.8kg foil is nicer than a 4.5kg foil but doesn’t come from the same maker.
But going from solid fuse to hollow or carbon can save you 0.5kg or so and might be worth it.
When it matters is when you are trying to decide whether to buy a great new surf wing or speed wing for your heavy brand X set, or spend more to get something all carbon that weighs say 2.5kg instead.

If you get all the small changes at once, it could make a big difference!


Return to “Hydrofoil”

Who is online

Users browsing this forum: fun2kite and 4 guests

cron