Show me a cracked metal socket style connection!
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Isn’t a single screw through the side what Armstrong did with their fuse?
Omen have a titanium fuse option too if you like shiny titanium things. 
Here’s a link. Fuselage – Omen Foils
Today in the IQfoil windsurf Olympic class they uae two side screw and seems to have very st iff connection
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Looks similar to the ancient MFC fuselage, when the MFC Hydros and Helios switched to an aluminium fuselage for more strength.
The omen fuse is also titanium. Look at the omen agent thread for a picture vs afs carbon.
Edit: looks like hdip beat me to it, but still worth taking a look at the agent thread for a picture
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For completeness here is the Omen fuse/mast.
and a side by side from the Omen thread:
I do like the look of that as an industry standard candidate. On of the better socket setups
Here is one for the engineers:
what about a footless mast. Just run the foiled carbon right to the end, and have a matching routed internal profile cut to the fuse to match the mast shape.
And then hole(s) to allow the cross bolts ala Hydrocraft
the advantages
- manufacturability. The mast is just a continuous bit of carbon, no foot, no inserts. no defects, no failures
- customisability. mast too long. chop it off, sand it flat, bang another hole(s)
- strength. no carbon at odd angles. carbon just runs straight down always
- countless other benefits
if you get very clever, you have the same on the tuttle end side
Couple of potential disadvantages too:
Two 8mm holes in the highest load area of the fuse.
Tight tolerance required with no taper will be a bitch to disassemble.
Any wear around the holes or mast slot and you’ll be riding a wobbly expensive bolt cutter.
But hydrocraft disproves all of those? all I’m suggesting is in effect removing the squared off foot from their system and just having fuse on raw mast
So appart from 3 side bolts and flexible fuse side walls needed for clamping force, Hydrocraft also has “top mount” bolt to seat the mast foot. And still needs to be tested for wear in saltwater.
Ah yes I forgot the last bolt. Seems maybe excessive. Their original had only the side bolts but I can see why they added that last one.
The manufacturability was where I thought it might have merit given how expensive masts are and how overbuilt they are. Looking at my Code setup the mast foot is a lot of carbon, lots of intricate work, and as you say any slight issue with tolerance and it’s completely useless (and then the mast base, also about a kilogram of carbon that could be lost to a tuttle). If a mast is expensive because of carbon cost and labour costs, it’s obvious to see where you could shed it
Speculation: but i think the main reason for the top bolt is to allow the foil to be removed without taking the plane apart. The first iteration of the design used bolt hole through the foot and you had to remove the whole plate which made the front and tail come apart as well. The new design uses a slotted foot so you can just loosen the side screws to remove the whole plane.
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I hope you’re right. But judging by the “make sure it’s seated” part of their last assembly video, i suspect they are relying on that bolt and the mast base seat for fore-aft stiffness. A grain of sand in there and you have a single center-lined bolt in cyclic bending and/or relying on enough friction on your clamped side walls. Time will tell.
Yeah but the moment you design a different mast you now just have a mast shaped interface.
Also, the bigger foot gives someplace for the hardware to go.
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I tested one in hood river a month ago. I wouldn’t have any qualms about running it without the top screw. Sure the hydrocraft boys wouldn’t recommend this though
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yes, this honestly is the best reason for this. A mast is now double or triple the cost of the rest of the foil system. It’s by far the biggest investment. Everything should be designed around the mast. Currently we’ve got big chunky mast foots for pump foils etc (the fuse tail wags the mast dog)
Two other notes from looking at my Code and AFS fuses
- We are well on the way to <80mm <11mm masts, and then they all seemingly balloon out to a fuse or system designed for a 19mm mast. if the mast is 11mm, do we need more than that for the fuse interface. This explains the F4 system where they’ve gone straight to titanium mast foot, which seems sensible. My guess is that given that massive breakthrough and massively positive adoption. The idea that there will be industry standard seems laughable! Which is good! I guess?.
- Per picture below, the bulk of the fuse behind the mast is mostly wasted. I feel like that could be fined down to a laughably thin titanium rod and still achieve the purpose? anyone considered that? Or is it torsion from the longer arm? for an XS sized fuse, it feels way overbuilt. Omen has the right idea here with their very thin fuse
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I don’t think that picture tells the whole story! I’m pretty sure that’s compression and the back of the mast is in tension there! If I had to pick to run only one of my mast bolts it would be the back one so I can’t say it’s doing nothing.
also, jeez it seems like we had not of those in the past. Takuma, yeah, everyone loved that connection right? For real though I gotta have m8 fasteners and there should be some level of conical shape to it so those point to a larger connection. It, however, shouldn’t be too big because that eats into the fuse and causes the fuse to either be weak or huge.
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that simulation is with one half of the main wing loaded, basically what happens when you do a full wingout turn just before you crash 
. It doesn’t model the downforce from the tail, so in reality there would also be some stress on the aft part of the fuse although it would be almost all direct downforce with only a small torque component. It’s important that the rear fuse is stiff, so while it can be made thinner (low torque/side loading) it should still be tall.
a lot of the size of the mast foot/fuse is there to accommodate threaded inserts and to keep the fuse stiff. The F4 solution is to make the whole foot into the threaded insert (conceptually similar to the old Nolimtz), it’s a good way to reduce profile but the engineering and production of the metal/carbon interface has to be really good. Epoxy doesn’t stick to metal very well and the different thermal expansion rates of metal and carbon/epoxy means the bond will most likely fail at some point so there needs to be a mechanical bond of some sort to keep things in place.
I have ended up with something that’s sort of a cross between your idea and the F4/Nolimiz concept. It’s a short metal fuse that’s permanently bonded to the mast with the mast slotted into the fuse and bonded and pinned in place. Bonding means that there’s no slop and tolerances aren’t a problem. There are no metal inserts in the mast and the fuse can be replaced if necessary due to stripped threads/corrosion or whatever.
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Slingshot already did this in 2020. Believe it was part of infinity 99 setup.