Building thornback Mk II designed by Ian Newham with custom panel layout.I just discovered this forum and noticed that Ian Newham is a moderator here so I thought I would post my build here as well. Credits go mostly to Ian since this was based on his plans.
This is my first build except for the plastic bag version of 66% Thornback made just before this build.
Thornback Mk II designed by Ian Newham with custom panel layoutName: Thornback Mk II
Weight: 307g (without tail weight and bridle)
Wingspan: unknown
Sail:
White Icarex P31
Midnight Blue Icarex P31 (black wasn’t in stock anywhere within 600km from here)
Dacron tape (25mm folded in half for trailing edge, 50mm folded for leading edge, 70mm for nose pocket, mixed for wing/tail tensioning and various reinforcements)
Sports bag material black (nose reinforcement, heavy duty stuff, much stronger than your usual Sports bag)
Sewing tape 6mm (double sided tape applied to every seam without exception)
Frame:
6mm hollow carbon spars (the whole frame)
3mm carbon spar (stand-offs
3x end-cap
3x split nock
4x stand-off connector
4x JACO stand-off sail grabber
4x EOLO leading edge connector
1x EOLO middle T
Lines: 78kg dyneema (leech line, wingtip tensioning line, flying line leaders, yo-yo line)
75kg 2x30m Climax Profiline set (flying lines)
70kg dyneema bridle line (this things stretches :-( )
Thick polyester line (this is for handles)
KitebuildingSail
I made a point to align everything 100%. I used same colored thread for sewing the sail. White for while parts, blue for blue parts and surprise surprise black fro black parts to ensure that the sails looks as clean as possible and my mistakes are less noticeable. My sewing machine often dropped a stitch and this way you will not notice as much. It is also much harder to notice that my thread torn more than 10 times when I was sewing the trailing edge. When I was assembling the sail I first applied sewing tape to one piece of sail. Then I secured it on the board and aligned with the next piece. When everything aligned 100% I took off the cover film and taped those pieces together. That is also the reason why I’ve chosen to sew everything with shorter 3 step zig zag stitch instead of the long one that most people use. Since taped seams hold very well by themselves I considered sewing is mostly cosmetic and I like these shorter seams better.
All pieces of the sail are have their pattern aligned with the spine except the long piece that goes along leading edge. That one is aligned with the leading edge because it’s mostly tensioned from nose to wingtip due to the curve on the leading edge.
The trailing edge is reinforce by mylar along the full length on the back side of the sail. Mylar reinforcement is also applied to the spine along where the 2 halves join. It’s 20mm wide so that it aligns perfectly with the overlapping Icarex and it’s all sewn through together.
Wingtips
I don’t want to put any holes in the sail until I absolutely have to. Holes can always be added but removing them really requires very good knowledge of black magic and I’m afraid I skipped a few lessons here and there. So I decided to sew in a small loop from 25mm Dacron folded in thirds. Small enough so that it is barely noticeable and just big enough to get the dyneema line through it. I also didn’t want to sew anything on the back side of the kite so the order in which it is done is from inside out is: sail + Mylar, leech line, trailing edge, Dacron loop and finally leading edge. The sewing that you see had to be done by hand because I had to sew through all that material and if I count correctly it’s 12 layers of Dacron + Icarex + Mylar + Dyneema line and as a sewing bonus it’s also 10 layers of sewing tape. That’s 22 layers of stuff to sew through. I did the holes using sewing machine and sewing was done by 2 needles crossing themselves from opposite sides. If this breaks down then I can always make holes in it. The red line in this picture represent the leech line sewn into the trailing edge.
NoseI did a few changes to the nose. The nose bag was sewn after the leading edges. The order in which I put in the various pieces together can be seen on the last picture. This allowed me to try a few things before I decided on how exactly am I going to sew this thing together. I didn’t have any Kevlar at hand so I did the whole thing from cut pieces of 70mm Dacron strip. On top of it I used thick vinyl (or something) coated fabric that is similar to those used for sports bags. I originally purchased various webbing but this thing is same as strong yet much more pleasant to work with a cleans well too.
The front side of the nose is intact. I wasn’t comfortable cutting along the leading edge so I decided to do the cuts on the back side of the nose as you can see in 3rd picture. I did sew the front side of the leading edge but mainly to keep things in place. I will let you know after a few crashes if this nose holds to it’s promises.
Upper spreader reinforcement
Not much to say about these. Just your ordinary reinforcement secured by sewing tape and sewn.
Central T reinforcement
The central T reinforcement and spine tensioning is from one piece of Dacron. Sewing tape is applied between all layers of materials where the cutout is.
Spine tunnel and spine tensioningThe spine tunnel is from your usual 25mm Velcro positioned a bit further up to allow some space for placing weight between it and the split nock. The leech line is sew into the trailing edge as mentioned earlier and is from one long piece of Dyneema line. It is tensioned around the split nock as shown in the last picture. Then it goes inside the spine tunnel and is secured above the central T in a similar fashion the wingtips are. I’m not sure about how effective is the leech line going to be considered that the trailing edge is from a very stiff Dacron.
Further down to the end of the spine a second layer of Dacron is added to make the reinforcement stronger. The soft side of Velcro is sewn further down the reinforcement so that it aligns with the other half when the spine is tensioned. I made the soft side of Velcro 10mm shorter.
Stand-offs
As I mentioned before I don’t like making holes in the sail unless I am really forced. I sewn together 2 layers of Dacron. I punched 3+3 holes in this and added a third free layer underneath. This was applied to the sail before the trailing edges. If this proves ineffective I can still cut it off and punch some holes in the sail but so far seems to be fairly solid.
BridleI used the bridle described by FlyingWolf in his build of Thornback. Since I don’t know how to do any tricks yet with this kite I didn’t want to make an overly complicated bridle. His bridle seems perfect to me in the sense that it’s completely adjustable. The biggest letdown when making the bridle was the realization that my bridle line stretches quite a bit. On a 60cm line it stretched as far as 63-64 cm. I tried to pre-stretch it as much as I could prior to making any cuts and making both sides as symmetrical as possible but I have a feeling that this is going to be a problem sooner or later. Luckily the bridle line can always be easily changed.
FrameI made the frame exclusively out of 6mm hollow carbon spars because that’s the only thing I could get my hands on. If I feel that I need something more stiff for the lower spreaders I can always but it later. I wasn’t really sure how to exactly frame the kite by the instructions that I’ve read so I just used the measurement stated in Ian Newham’s plans. Except for the stand-offs which have been cut slightly shorter due to the way I implemented them. The spine is also a bit longer because I made the nose a little pointier and thus longer.
Once I get a good feeling of what a proper kite should feel like I will maybe make a different frame but for now I will learn with what I have.
HandlesAs the Tom’s Kitebuilding site says, if you can build your own kite, you can build your own handles. I chose this design because it feels comfortable. Both handles are made to fit my hand but the white ones are slightly smaller. Let’s say the white ones are meant for my lady and black ones for me but I intend to borrow the white ones quite often.
Kite bagIf you can build your own kite and your own handles why not a kite bag as well? It has pocket for spars, 8 pockets for kites and 7 pockets for handles/lines. From the outside it has normal handles in the middle and 3 pieces of white webbing with adjustable clips. Same thing but with thinner webbing strips is on the inside for every kite pocket.
My TipsI had quite a few difficulties when using my sewing machine that kept breaking my thread, dropping stitches, loosing tension on one side of the seam etc. most of this was resolved by adjusting various doodads but I did do a few adjustments that made the sewing job a bit more consistent.
1. Middle line - my machine doesn’t have one and I often needed it so I took a bit of transparent tape and permanent marker and made a very thin line (I just made a thick line on 2 pieces of tape that had very thin rift between them). To avoid smearing it I covered it with another piece of transparent tape.
2. Sewing guide - I couldn’t live without this improvised sewing guide when sewing the trailing edge and leading edge. It several pieces of vinyl covering tape put together to the precise height of my trailing edge. It’s also cute with a knife to have a clean edge to hold onto.
