Category Archives: Bow Kite

A Rainer Hoffman Bow Kite I built in the spring of 2006

Rainer Hoffman – Bow Kite Part IV

It’s the Easter long weekend and it’s raining… Perfect kite making weather! Finally got back to the Bow Kite today, and managed to finish it.

I still have a number of tweaks I want to do but essentially here is what I did.

I “borrowed” some 3mm fiberglass from a 6 foot circoflex that I made in Dieppe last fall for all of the discs except the number 1 and number 6 ( the two smallest). I planned on using some vinyl tubing type fittings to hold the curved spar against the horizontal spar at the back of the disc but didn’t bother. (this is one of the tweaks I may try).

Once I got all the curved spars in and cut to length I added the horizontal spars. I used Sky Shark P90s as it was all I had that was substantial enough. I let the spar protrude 1 inch on each side of the kite, this is to allow room for the end-caps and c-clips (do-hickies).

So for the challenging part, the tension lines. Since the largest HQ Nock I have is 6mm it would not fit over the SkyShark spars. So I thought I would drill them out… BAD Idea… I Don’t have precise enough equipment and I think it would have been far too thin anyway. So back to the drawing board. I fought with vinyl end caps for a while trying to figure out how to tie the knots so that I could guarantee everything would be even and symmetrical etc… again no luck.

The problem I had was knowing how long to make each line segment and how much line would be soaked up by the knot/loop that I was going to use. So I got a pencil and paper and went to work figuring out the length of each segment’s tension line. So the first one was pretty easy. Since the discs and the main sail are 90 degrees and the tension line would form a right angle triangle, all I had to do was dust off my trigonometry and the Pythagorean Theorem. :) So the first segment is 66.8 cm. I was off to a good start, but then I started looking at the other segments and realized I couldn’t calculate the rest using the same formula. With a bit of figuring and the help of excel I was able to calculate all the segment lengths. Although most of the segment lengths a roughly within a cm of each other (except the top and bottom) I still found my excel calculator helpful as I could enter the spar diameter and determine how much extra line I would need for the loop and knot.

Then I just marked off each section on the tension line, used the knot allowance to tie a loop and that was almost the same diameter of the spar. I simply slipped it over the spar, added a c-clip to keep it in place. Finished it off with a vinyl end cap on the spar. It worked very well, and was simple and precise (and I hop accurate ;) ).

I have published the calculator here.. if you would like to have a look (and verify my math) :D

So after all that here is the result! Of course it was raining when I finished it and no wind.. so the in flight pics are me running like a mad man down my drive way.

don’t ask who the goofy guy is :)

Rainer Hoffman – Bow Kite Part III

Got a chance to work on my Bow Kite today.

So I finished binding the discs, and the body panels. Then I added the dacron sleeve and all attachment points to the discs and sewed the whole thing together. It was a very busy day! :)

The last thing I did before I packed it in was added the long main leading edge framework. I used SkyShark P100s but may switch to P200 or P300 depending on the stiffness.

I have to get some long fiberglass rods for the curved discs.. time to put in an order at I guess :)

Here is a photo of the progress I made today.

© 2006

Rainer Hoffman – Bow Kite Part II

I didn’t get a chance to work on this kite last night, I had a repair job to do on a badly beaten HQ Tramontana.. what a night..

Anyhow on to the Bow Kite. Tonight I started to edge bind the horizontal discs that cross cut the kite every 40 cm or so. These disks are edge bound in such a way to create a sleeve for a 2mm carbon or fiberglass rod. The problem I ran into was that the discs #1 and #6 have such a narrow curve at the top that I was getting terrible puckers which resulted in a baggy sail when the rod was installed. I really wanted to use the Mil spec gorss grain I had purchased from but it wasn’t going to cut it for this small of a radius.

I turned to a good discussion on the forums titled “curved top banner” (forum registration required) which outlined several methods for sewing these types of curves. I tried a number of the suggestions but settled on using 3/4″ strips 1.5 oz fabric (ripstop) cut on the bias. This worked really really well, I have to say I never realised how well it actually worked until this evening, I have sewn curves before but never this tight. In this case I think the only thing that would work is fabric cut on the bias. Chalk it up as a learning experience and move on…

So after all that experimentation I only managed to get two of the discs sewn… Tada…

©2006 ©2006

Rainer Hoffman – Bow Kite forum member “Erhan” posted a picture of a kite he made from plans published in the German magazine “Kites and Friends”. This kite is designed by Rainer Hoffman and is simply called the “Bow Kite”. Invento-HQ kites has licensed the design and is offering it for sale this season. Based on this website I have started to build a bow kite and will, as usual, blog my progress.

Here is where I am so far.

Patterns for the cross-cutting disks have been cut as well as the fabric
Patterns for the main body pieces have been cut as well as the fabric.

hmmm doesn’t sound like much but it took the better part of the afternoon and evening to get that far.

Here is a photoshop quick and dirty mock up of what it will look like when done as well as a photo of the body pieces cut and ready for edge binding.

click for larger image

click for larger image