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Adam555 said..
Yes a lot more work than I 1st thought lying on the couch! but really happy with result - my old man did a great job machining it

absolutely hanging out to go for a sail...Physio thinks another few weeks though with the broken foot...as soon a I test I'll post something !

Better make another one Adam. Your old man could come out of retirement.

Ok been back sailing now 2 weeks since breaking my foot in May and have had x4 sails on the RSX with modified/ extended fuselage in varying conditions

Overall am very very happy with the outcome- feels a lot more stable longitudinaly and you certainly have more time to adjust height wise, won't lie am a bit rusty after months off with the broken foot but 2nd sail back after 5 months off was on the foil and wasn't an issue - biggest problem Ive had has been with 'foot strap phyobia' especially with a foot that still has screws and plates in but will post something on that separately


Also Side by side with Craig's NP F4 showing the extra length of the RSX now in the background ..note Craig had done an amazing carbon extension on his F4 of about 80mm as well already


Next step is to get down to Mandurah for a sail with Elmo and Stroppo to do a side by side comparison with the std RSX

Regards Adam

Don't worry about the pins. I've had 3 in the right ankle joint, 6 in the left tib/fib, 2 in the left pinkie, 1 in the left pinkie, and not affected when windsurfinf or playing tennis.
I used Rich Miller's double mast foil in the late '80's. Turning was the drawback.
Just got the 120cm fuselage RRD after using the Naish system..no wind in past 2 weeks.

Nice one Adam glad your getting back in the swing of things it will be cool to see how it goes in comparison to the standard setup

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LeeD said..
Don't worry about the pins. I've had 3 in the right ankle joint, 6 in the left tib/fib, 2 in the left pinkie, 1 in the left pinkie, and not affected when windsurfinf or playing tennis.
I used Rich Miller's double mast foil in the late '80's. Turning was the drawback.
Just got the 120cm fuselage RRD after using the Naish system..no wind in past 2 weeks.

Thanks Lee biggest issue I'm finding (after the initial paranoia about getting foot stuck in the strap) is the skin wearing away above one of the plates .. may need to wear a bootie on the foot !!

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stroppo said..
Nice one Adam glad your getting back in the swing of things it will be cool to see how it goes in comparison to the standard setup

Looking forward to it Stroppo

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Adam555 said..

Great job Adam!
Why front tip is this blunt? It generates more drag.

Does it though? Depends significantly on what the critical Reynolds numbers are for that section within the foils operating speed range.

What does the nose of a dolphin look like? ;) Food for thought.

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CJW said..
Does it though? Depends significantly on what the critical Reynolds numbers are for that section within the foils operating speed range.

What does the nose of a dolphin look like? ;) Food for thought.

or a big ship

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mm7 said..

Adam555 said..

Great job Adam!
Why front tip is this blunt? It generates more drag.

Mm7 lots of sailing on this now in quite varying conditions. Nose of the fuselage is rounded but not super pointy as you note

Certainly the extra length is much more stable verses orginal one I'm not quite sure the blunt nose on the fuselage effects things speed wise persay but my gut feel after a sail against guys on similar unmodified RSX foils recently suggests is slower but still a bit unclear if this is the extra length which i think also reduces the speed - this effect is quite well documented in sailing boat keels. The other factor is sailing ability !! so lots at play.

Key though in my mind is comfort and ability to keep stable which I'm convinced a fuselage around the 90cm-100cm gives

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Adam555 said..


Mm7 lots of sailing on this now in quite varying conditions. Nose of the fuselage is rounded but not super pointy as you note

Certainly the extra length is much more stable verses orginal one I'm not quite sure the blunt nose on the fuselage effects things speed wise persay but my gut feel after a sail against guys on similar unmodified RSX foils recently suggests is slower but still a bit unclear if this is the extra length which i think also reduces the speed - this effect is quite well documented in sailing boat keels. The other factor is sailing ability !! so lots at play.

Key though in my mind is comfort and ability to keep stable which I'm convinced a fuselage around the 90cm-100cm gives

The main thing - you enjoy it!

Length adds to resistance because it increases surface, and so surface (skin) friction.
In case of narrow fuselage it is very minimal addition. I would not worry about.
Long fuse allows to decrease size and/or AoA of stab, while keeping tail volume in comfortable stabilisation zone.
Smaller and less aggressive stab will have less drag.

@CJV
of cource drag will depend on speed. RN in our case is used mostly for comparisons, like ship and its lab model should have same RN during tests (but different speed). Which section are you going to compare? IMHO what should be compared here is the length of the tip itself. Blunt tip is shorter. Pointy tip is longer ,i.e. 4 times, so its R will be 4 times higher for same speed and water viscosity. It means that turbulence will appear x4 later.
Regarding drag coeff of shapes look here https://www.grc.nasa.gov/www/k-12/airplane/shaped.html.

Re dolphin nose. What does the nose of blue marlin looks like? The fastest fish. ;) Food for thought.
Try to sell your "blunt dophin nose" idea to rowing boat sport people. What would they say? :)

Ok by way of an update have been using the modified fuselage now since November last year and it's clear that the extra length really works ...makes the control up/ down so much more controllable/ predictable and you feel it when you revert back to a shorter fuselage.

Original home made fuselage though has had a few issues though despite the anodising and a lot of attention around the machining surface finish these include:-

Micro cracking and corrosion around the front screw that holds the mast on


Corrosion where the mast fits into the fuselage... a well known issue with carbon fibre connected to aluminium ... new one to me but effects are clear !


Also discovered was Incorrect aluminium used... thought it was 6061 T6 but actually checked receipt again was 2011 which doesn't have good corrosion resistance properties

We're making a new one now which will be 1m long that will correct the above issues ie 6061 aluminium plus will be a bit of a Swiss Army knife ie able to take Starboard, RSX and the new NP glide wings .I think the ability to take multiple brand wings means you can pick and choose the best of everything or at least try it plus the NP RSX mast is super stiff so is good to stick with this ... see below design complete and machining underway.




For the carbon mast to fuselage interface I've bought some castable plastic that I'll pour around the mast installed in an oversized slot on the fuselage. Sets to 82D hardness which is like basically like the hardhat material.

While am waiting for the new 1m fuselage have also been trialling a very simple concept to extend the fuselage on my original RSX fuselage - this seemed to work really well on my first try last week but want to use a few more times to get firm opinion on it ie




Outside of this have a nice interesting seperate project on the go as well with lots of support from Reg and Dan at Windsurfing PERTH (WSP) involving making a simple kit to convert the old NP pink Ali's into Np glides with extended fuselage (900mm+) ie is basically two adaptors that will involve no modifications or machining to the original fuselage .... will post something on this separately ie 1st one is ready to try but is untested ...hopefully we get some wind to try next week.

Nice update! Corrosion looks wild but I guess Alu2011 is a copper alloy so doesn't help. Starboard use a plastic interface similar to what you are making on their race foil to insulate the mast from the fuselage. Good idea on making it modular-ish, will open up a lot more options.

Do you race with that foil? If so consider also having the option to move the whole fuselage forward relative to the mast. Not easy due to the slot but could be done with addition of wedge spacers etc. I say this because that foil, like my F4:flight has quite a short front wing-mast distance, for racing anyway. I've extended mine again, out the front this time, 130mm. Now the fuse has 300mm added to the back, 130mm added out the front....basically I built a starboard race foil ahahha. Is a winner for racing though and my front wing is actually further forward that the SB race relative the mast, looks similar to their new 1150 Plus+ fuselage.

By a small zinc anode from a chandelry machine it down to reasonable size and attach it to the fuselage or make some zinc screws and fit them to the unused holes

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elmo said..
By a small zinc anode from a chandelry machine it down to reasonable size and attach it to the fuselage or make some zinc screws and fit them to the unused holes

Thanks Elmo must admit didn't think of this simple approach as was so focussed on wrong material and isolating the carbon - will look at doing this if next one has issues

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CJW said..
Nice update! Corrosion looks wild but I guess Alu2011 is a copper alloy so doesn't help. Starboard use a plastic interface similar to what you are making on their race foil to insulate the mast from the fuselage. Good idea on making it modular-ish, will open up a lot more options.

Do you race with that foil? If so consider also having the option to move the whole fuselage forward relative to the mast. Not easy due to the slot but could be done with addition of wedge spacers etc. I say this because that foil, like my F4:flight has quite a short front wing-mast distance, for racing anyway. I've extended mine again, out the front this time, 130mm. Now the fuse has 300mm added to the back, 130mm added out the front....basically I built a starboard race foil ahahha. Is a winner for racing though and my front wing is actually further forward that the SB race relative the mast, looks similar to their new 1150 Plus+ fuselage.

Hi cjw
no racing just fast cruising! I did think about having more forward wing positions on a slightly longer fuselage again but decided against it in the end as always found the upward force at the front ok where it was relative to the straps etc - curios though as to what have noticed by going further forwards from a racing perspective ie are you pointing higher or is it better coming downwind ?
Thanks
Adam

It just moves the balance forward which is particularly advantageous when it's light and going upwind, not so much going downwind. When you have the board cranked to windward upwind, with the main foil back further the nose tends to drop, to counteract this you need more back foot pressure and have to pull with the front foot a bit, same when it's light. This isn't an issue with the front wing forward, the overall balance in a range of conditions is much better; in short it's just way less effort to sail it fast at high angles over a larger range of conditions. Downwind it's a little trickier as the power is further forward but manageable. Foil gybing is also way easier as the main lift is very central.

I kind of new this from when I first started modifying the F4:Flight but as you probably know, extending the front of the full carbon F4 foil is no trivial matter, so rear it was (not that that was easy wither). However, I had one sail of a starboard racefoil setup in my board and it confirmed all my theories so it had to be done, for interests sake. Starboard obviously did a lot of testing in this area when they developed their race foil and it shows, they were way ahead of everyone on that curve but they weren't available yet when I bought the F4.

Still, this is kinda race stuff. For all intents and purposes it was fine as it was with the 300mm rear extension, that alone transformed the foil, as you have found with your mods. We're talking here about that extra degree or two of angle upwind and just overall balance when racing, making it less effort to sail it fast.

Ok finished fuselage per below next step is trial fitting some SB wings then we'll make the filler pieces/ adaptors for the RSX wings and NP glide wings, anodise and pour the plastic in the mast slot. Made stainless inserts again for the threaded holes - not sure if this is necessary but worked well on last one

Reading CJW's great thread has inspired me to post a few pictures of progress on this winter project...which hasn't been huge but have now cast the plastic insert for the mast using a 2-part product that sets to about 82D shore hardness (same a Hard hat)


This enabled a simple essentially square slot for the mast to be machined in the fuselage and picked up the taper fit of the RSX mast plus provides the isolation from a corrosion standpoint. Final product came out pretty well ie


Next up had to make the two slots exactly fit the starboard wings before making the aluminium inserts/ blanks that blank the starboard slots enabling a RSX or NP glide wing to be used - fit came out nice ie




Blanks get machined next then off to anodiser and test run !!

Looking good! Cast insert looks mint, I've never used that stuff before, will have to give it a go on something. Do you plan to run the SB wings? Good idea either way, like you say can run whatever you wish. Look forward to hearing the results.

could you inform, how you modified the NP Pink AL foil thx.

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CJW said..
Looking good! Cast insert looks mint, I've never used that stuff before, will have to give it a go on something. Do you plan to run the SB wings? Good idea either way, like you say can run whatever you wish. Look forward to hearing the results.

Hi CjW,
apologies for tardy reply but have been off in Africa for the past month. Plan is to run the SB larger 1100mm front wing for the lighter conditions and potentially try a few of the other starboard wing options. Finished fuselage etc after anodising is ready to go .. just need to try it !

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Duamanix said..
could you inform, how you modified the NP Pink AL foil thx.

Hi Duamanix
apologies for slow response but have been away. I'll put a whole new thread on the NP pinkie mods later this week as the testing etc of all the various options has taken me a lot longer than planned and are still ongoing ie was actually trialling a new set of extensions tonight plus work has got in the way for the past month!

Regards

Adam

Thx, "make the pinky Great Alain"

Had a private showing of Adams Pink (and golden) bits yesterday

All I can say is Holey sheet, that wee beastie is going to be a lot of fun