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Onda633 fuselage too heavy, any way to make a carbon one?

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fun2kite
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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby fun2kite » Wed Dec 19, 2018 2:35 am

How does going "mono" (cutting out the back of the fuselage) affects the mast and especially mast inserts?

Before, the stab was putting some opposite force and distributing load to both bolts holding the fuselage to the mast, but once you cut the back out, don't you wind up with more force on the front insert. Or maybe more like a force that wants to rip-out the back one and putting more inward pressure on the front insert?

Is this a concern for the mast or not really?

Horst Sergio wrote:
Wed Dec 12, 2018 1:40 pm
I am sure the Onda will be easy and great for mono, so just try it.

Kitejunkie-GONG-Mono-convertible-fuselage.JPG

If you want to go light, go mono :wink:

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby downunder » Wed Dec 19, 2018 2:47 am

Good question.

But again, his weight is less than 60kg ;) We talking a different world all together, something heavier riders can't understand.

Riding stables would mean at least 4 bolts or a permanent fuse in my books. But that's me.

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby Peter_Frank » Wed Dec 19, 2018 7:57 am

No, on the contrary.

Removing the rear stab will typically put the COE slightly back, so you have to move a bit back on the board too.

Meaning less stress on the fuselage-mast joint.

Remember, the stab usually pulls a bit down, whereas the front wing pulls up - and now you remove the rear stab pulling down, meaning less stress on the fuselage joint.

OR, one could say, that maybe the mast should be put a bit further back for same load distribution - but that is not necessarily as simple, as turning dynamics changes when without a stab, so it might have to be seen as a new world of how to trim :D

8) PF

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby downunder » Wed Dec 19, 2018 8:28 am

^
How when the leverage now is much bigger on one side only?

Way more stress. We talking a "console" in stress mechanics, and before removing a stab was "beam" with "two support" something like this:

https://d2vlcm61l7u1fs.cloudfront.net/m ... 7kIHCR.png

with P as mast and support as wings.

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby Peter_Frank » Wed Dec 19, 2018 9:12 am

downunder wrote:
Wed Dec 19, 2018 8:28 am
^
How when the leverage now is much bigger on one side only?

Way more stress. We talking a "console" in stress mechanics, and before removing a stab was "beam" with "two support" something like this:

https://d2vlcm61l7u1fs.cloudfront.net/m ... 7kIHCR.png

with P as mast and support as wings.

Nope, as said, it is quite opposite - the leverage from the stabilizer gives you a higher amount of stress, because it pulls down while the main wing pulls up (lifts).

So the total leverage from the wings are "smaller", when you remove the stab, meaning less stress :thumb:

If you had the stabilizer trimmed "oddly" so it pulled up (I dont think anyone does that, when not a canard), then you are right, the COE would move rearwards, thus giving less stress on the fuselage-mast joint yes.
Exactly as if you removed the stabilizer, also moving the COE rearwards, giving less stress.

IF, you dont move the mast rear on the fuselage, as it maybe should be...

Trimming the stab quite neutral is used, and pulling a bit down the standard, but I dont think "up" is used :roll:

8) PF

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby downunder » Wed Dec 19, 2018 9:41 am

Put it this way, jump and land dead flat. Not even flat, lets say slightly up with LE so not cutting into the water...What happens?

When hit the bottom with a wing LE?

What happens is the moment of inertia (MOI), which puts a huge stress on one side only. There is no back wing, so no resistance to moi.

I've seen the French HF for riding as TT, with all bolts snapped when hit the bottom. This is pure symmetrical setup. Mono is asymmetrical = MOI, hence way easier to snap the bolts. Any side bolts. Hence I would use 4, coz if side bolts snap, only one will remain.

Sure, if the mast is directly on top of the wing, no much moi.

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Re: Onda633 fuselage too heavy, any way to make a carbon one?

Postby Horst Sergio » Wed Dec 19, 2018 11:23 pm

@fun2kite:
No, no concerns necessary about static of monofoiling. You just need law of lever forces to see, that a complete monofoil (board and foil) in comparison to a stabi foil can always be significant lighter than a stabi foil, as also PF said.
Not just because of cutting the fuse, but because, the strut goes more forward under the board, and the wing can be smaller and with a lower AR to reach the same takeoff and glide ratio, and this all means less lever, less forces.

But better discuss it here: http://kiteforum.com/viewtopic.php?f=19 ... e#p1032665 where I should have already writen about this.

Now its on omg to choose a solution, but especially for traveling I would not prefer an experimental fuselage that could break, just to save a few 100 gramms ...

Oh, and building an even 1,0 kg Monofoil will work for sure, I have already an old Horue strut with a broken fuselage here to test this one time. But when trying two of the about 1,2-1,3 kg HORUE foils, I never liked it to ride these "on eggs" just in mind, to not break them. Just check the HORUE videos, great stuff, but Phil never lands the H13/H14 hard, mostly not even lands it, but puts the foil a side and himself in the drink. :roll:


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