Author Topic: Short fuselage opinions  (Read 1311 times)

SUPeter

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Short fuselage opinions
« on: March 30, 2020, 12:20:55 PM »
I am redesigning my fuselage.  More in line with the Axis foils set up except for it being full carbon ( old carbon fiber hockey stick filled with solid carbon).   Just curious. Im wondering if making the fuse shorter will help with pumping.  Already planning on a smaller tail wing.  Im pretty sure Ill just have multiple tail wing mounts on the fuselage which will allow me some room for experimentation.  Thanks in advance
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Piros

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Re: Short fuselage opinions
« Reply #1 on: March 30, 2020, 09:02:17 PM »
The shorter fuse and smaller tail wing can feel really unstable and twitchy at first. Some riders try it and go straight back to their std setup again , you need to stick with it for a couple of sessions and you quickly settle into it with more speed and a much tighter turning arc. The pumps takes a bit more to get used to as the pump arc is much shorter and faster , as you settle into that you'll find you pump much more efficient with a reduced motion travelling further between each pump. Another advantage of both the shorter fuse and smaller tail wing is tackling foam balls , you have much more control and far less likely to get boosted. 
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SUPeter

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Re: Short fuselage opinions
« Reply #2 on: April 07, 2020, 08:44:31 AM »
Thankyou Piros for that information.  I think I am going to have 2 separate mounting positions for my reduced surface area stabilizer wing.  One standard length and one shorter length.  I appreciate you mentioning the other noticeable differences.  Sounds like a bit of a learning curve.

supmmmm

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Re: Short fuselage opinions
« Reply #3 on: April 07, 2020, 09:02:37 PM »
If I may - is the length of the fuselage measured end to end - or center of front wing to center of rear stabilizer?

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VB_Foil

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Re: Short fuselage opinions
« Reply #4 on: April 08, 2020, 07:28:36 AM »
I like Sky Rama's post on insta regarding standardizing the fuselage length measurement:

Im a 59 65kg rider:

Boards:
   4'5.5" 33L Armstrong
   410 37L FSM
   5'1" 74L FSM
   511 100L FSM

Foils: Armstrong 1050, 1200, 1550, 2400
Wings: F-One Swing 3.5M and 5M

surfcowboy

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Re: Short fuselage opinions
« Reply #5 on: April 08, 2020, 08:51:41 AM »
SupPeter, as usual, you solve a diy mystery.

Ive been wanting to make a carbon version of my heavy Gong fuselage. Its square already and ripe for an easy build out. Ive been looking at molding one but had thought of buying square carbon tube from RockWest.

Your filling process, are you using a mix of chopped carbon like they do for so-called carbon forged parts? And how are you getting a good mix and pressure? I envisioned making a plunger that would press it in with just a bit of clearance so the extra resin could squeeze out and be cleaned up before it set and then doing that in maybe 3-4 layers. Youd lose some of the absolute strength of a fill linear fabric layup but I assume that the outside and the chopped inner would be enough.

Whats your version?

PonoBill

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Re: Short fuselage opinions
« Reply #6 on: April 08, 2020, 10:06:27 AM »
I'm not really good enough to be sensitive to different setups, but I find the shorter fuselage and small rear wing to be much easier to pump once I'm up and foiling and easier to get up off the water in light wind. I couldn't get the slightly smaller tail I wanted--looking to try the 370 tail vs the 440 Axis I've been using on a short fuselage. Mark Raaphorst had a 340, which looks ridiculously small, but I took it anyway, and I like it a lot. It feels like the tail skids sometimes--reminds me of a windsurfing fin sliding out after a jump, but that doesn't really bother me. Unlike a "cavitating" fin it stops sliding by itself with no correction. Even my weak pumping on takeoff is enough to get the board bouncing on the surface, which is usually enough drag reduction to accelerate and pop right up.

My next purchase will be the ultrashort fuselage, and probably the carbon mast.

But first I've got to get back in the water.
« Last Edit: April 08, 2020, 10:10:31 AM by PonoBill »
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.

surfcowboy

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Re: Short fuselage opinions
« Reply #7 on: April 08, 2020, 12:32:42 PM »
Pono, Kane DeWild talks about the levels verticality on tails affecting that slide put feeling. Seems like smaller with some vertical would be a good experiment. He mentions this on the Progression Project podcast. Also talks about how chopped tails my lose their up or down turned tips which might affect things more due to changing 2 variables.

SUPeter

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Re: Short fuselage opinions
« Reply #8 on: April 09, 2020, 05:29:10 AM »
Thank you everyone for your replies and input.  Please read the following at your own peril.  I tend to spend far too much time tweaking builds.

For the tail piece,
I used the blade insert which was naturally tapered toward the blade with the blade cut off.  The natural taper is what the blade was attached to and the fitted end is what telescopes into the carbon fiber shaft .  I then added a little more carbon and fill to the very end of this tail piece to finish fairing to a nice clean and sharp but wide end.   I plan on leaving this end about 1 inch in vertical length to help with directional stabilization.
The shaft itself is filled with, guess what, carbon tow.  I start with a very small strip of wood ( 1/2" x 1/4" x 24") and I lay wet out strands( multiple) of carbon tow longitudinally, on all 4 sides of the wood strip.  After longitudinal strands are cured and filed to shape, I then wrap wet out carbon tow circumferentially around this in a diagonal pattern to help with decreasing twist in final product.  I then let this cure and with-out filing, begin again to lay out longitudinal strips of wet out carbon tow on all four sides.  Using a wax release on the inside of  lengths of aluminum right angle helps with shaping these additions.  Remember, you are trying to produce an insert, closely resembling the shape of the inside of your hockey stick shaft.  Once you are close to size or a little over, file to shape so it fits inside shaft with a little room to spare.  Do your best to sand the inside of  the hockey stick shaft.
Place finished insert vertical in a vice.  Place shaft just over the top of insert, 1/2" or so.  Pour in a semi -viscous mixture of epoxy, milled fibers, aluminum powder, wood flour.  Fill the hockey shaft maybe 3-4" in depth with epoxy filler.  Slowly slide shaft down over insert being careful not to let epoxy fill level run low.  I seemed to get a good fill between the insert and the shaft tube.  The result seems more than adequate as far as strength is concerned.  Ill know more later when I get a front wing attached.  My wing attachment will be much like the aluminum Axis wing attachment.  That's a whole other description.

surfcowboy

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Re: Short fuselage opinions
« Reply #9 on: April 09, 2020, 08:23:20 PM »
I love it. I have to buy a roll of tow just to mess with.

I followed you all the way til the end but Im not sure how you are getting the resin on the insert exactly. It sounds like you start with maybe 3/4 of resin in the shaft and then turn it upside down and slide it over the insert?

If so, how do you get more resin mix on the insert as you go? Do you paint it on as you go down?

SUPeter

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Re: Short fuselage opinions
« Reply #10 on: April 11, 2020, 12:40:23 PM »
Yes, I coat the insert as well as keep enough filler inside the shaft as I slide the hollow shaft down over the insert.  Judging by the amount of filler entering the space between the insert and the hollow shaft I am guessing that the filler is doing its job taking up the extra space and attaching the shaft to the insert.

Solent Foiler

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Re: Short fuselage opinions
« Reply #11 on: April 11, 2020, 02:00:00 PM »
How short does a fuse have to be to be considered 'short' currently? Appreciate it'll be a matter of opinion... Thanks
I'm 5'10", 65kg riding:
Naish Hover Crossover 120
Gong Catch 5'3"
on Naish foils (1250 & 1650).
Gong Plus wings - 4m, 5m

PonoBill

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Re: Short fuselage opinions
« Reply #12 on: April 11, 2020, 04:28:58 PM »
Axis ultra short is 62cm, short is 68 CM
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.