This dowel tetrahedral kite served as a test-bed for trying out various methods of attaching the spars together. As per the usual MBK approach, I was looking for low cost, a very short materials list and utter simplicity. This turned out to be almost impossible in a dowel tetra that would survive a bit of rough-and-tumble out on the flying field. However, I have since created a bamboo skewer version that ticks at least some of the required boxes!
Anyway, the Dowel Tetra did end up returning a few satisfying flights in smooth stiff winds down at a beach :-)
This kind of kite really is suited to handling strong wind. With at least 10 cells and enough stabilizing tail, the potential wing range would be truly enormous I think.
Even larger, more lightly built tetras can be very stable with no tail at all. The kite featured on this page was a bit heavy though, with 30cm x 5mm oak dowel spars. Plus plenty of boot-lace, wood glue and sails that were accidentally created in double-thickness plastic sheet! Never mind, it flew. There it is in the photo.
If you want to take a closer look at my other MBK designs...
The Big MBK E-book Bundle is a collection of printable PDF file downloads.
These short flight reports once appeared in the site blog page - that's the one you enter via the 'what's new!' site navigation link. Just scroll down and stop at any heading that appeals :-)
Tetra Takes Off
It's been a bit of an uphill battle getting a decent flight out of the heavy, crudely put-together 10-cell tetra...
Earlier today the breeze was great but misty rain persisted for hours on end. Finally the sun started to peep through small fast-moving gaps in the cloud cover. It was time to head for the beach. In search of smooth winds and soft sand.
Down at the beach, the breeze was just a fraction off-shore and this was causing a problem down on the sand... The wind was not so consistent after all. Also, the average strength of around 17kph would not be quite enough for a kite with such a high spar count!
So I headed home. But on passing a field that I sometimes use, it seemed worth another try. Just in case. On getting out and checking the wind, it was a fraction softer than at the beach. As you would expect. However, there was a huge amount of space to launch the kite. Not only that, but from time to time, really strong gusts were coming through. Real tree-top-waving stuff, that had to be well over 30kph. The stronger periods seemed to be associated with very light misty rain.
After several hops and flops (there's a new kiting turn of phrase!) I managed to get the kite out on over 30 meters of line. Great! This time, instead of a drogue that would frantically twist itself up in seconds, there were tails. Lesson - without a swivel, simple flexible drogues have their limits in fresh wind.
About 3 meters (10 feet) by half a meter (2 feet) of scrap drop-sheet plastic flowed from the downwind tip of the tetrahedron. Some longer and thinner loops of black plastic trailed from each side tip. Even so, the kite's stability was marginal due to excessive spar weight. But at least the kite flew around at a respectable line angle for several minutes in total. This was over a couple of flights, and both were captured on video.
Finally I walked up to the kite as it sat on the grass and discovered a boot-lace tie had given way. Most surprising, how a polyester boot-strap could just snap like that! Hopefully, a bigger kite with some flex in the spars won't be so incredibly hard on the joints. I'm pretty sure it's contact with the ground that really stresses those joints since it's a rigid structure. The corner cells seem to be the most vulnerable.
This tetra roughie has done it's job, teaching me many things about making and flying a 'quickie' tetrahedral design. Probably in under 15 minutes of total flying time!
Just had to get 2 H's in there ;-) ...
Wind speeds had built a little since the morning and the next few days were forecast to be lighter. So it was decided to have another go with the tetrahedral prototype. This time we went to a large square park in the hope of getting plenty of line out.
Although the tree-tops were waving about half the time, it proved difficult to get the kite up for more than say 10 or 20 seconds at a time. It's a real high-wind beast.
Sometimes the kite would dive straight at the ground before it got high and steadier. Fortunately, a tetrahedral will almost instantly right itself when line tension is suddenly relaxed. You just shove the winder at it. A life saver! Often this allows the kite to plop straight down relatively gently, avoiding hard contact with a point or an edge.
While it was nice to get the kite up and hovering on around 30 meters of line, eventually one bump too many broke a dowel. The next kite will be bigger, more lightly loaded (weight/area) and more accurately made. So, it will be doing far fewer take-offs and landings. The most crucial phase of flight for any aircraft :-) Still, I'm aiming to fly the next kite in winds of up to 50kph without in-flight failure.
Tetra Dodges Showers
The trouble with high-wind kites is... when there is enough wind, there is often rain also!
Such was the case today, but I had a go anyway. With gusts to 35 kph, the breeze was certainly ideal for lofting a 10-cell tetrahedral. Since this first tetra kite was on the heavy side, it was decided to fly it with a small drogue right from the outset.
A few lessons were leaned in the first few minutes. For example, the bottom cell will experience plenty of stress on it's front joint as the kite contacts the ground after sinking out. The first time this happened, the shoelace bow simply pulled out, with no damage. So a couple of turns around the joint before tying a bow will be the way to go in future. For that joint and all the others!
After a few short hops in gusts, a short flight or 2 was obtained on around 10 meters (30 feet) of 100 pound line. Very promising, although the drogue needed to be at least 50% bigger to really stabilize more adequately.
And then the rain came down, accompanied by much stronger gusts. I managed to get everything back into the car and waited for the rain to stop. At the next opportunity, out I went again. This time an even better flight was obtained on about 20 meters (60 feet) of line.
Unfortunately, rain soon arrived once again and so there was no opportunity to fly higher.
Taking the kite back to the car, it was noticed that a couple more joints had worked loose. Not to worry - those planned extra turns around the joints should take care of that problem.
The flights today were too brief to get any photos or footage. Annoying, but next time should be a different story...
First Tetra Tries
The weather was, as we say here in Oz, 'dodgy'. It was worth a try though...
Smooth winds high in the Moderate range would have been ideal for testing the new Dowel Tetrahedral kite. As it was, the breeze was quite variable and only gusted up towards 30kph every few minutes. It was during these short windows of opportunity that the kite struggled up for a few short flights. It's a heavy contraption, not designed to stay up in anything under 20kph really.
To avoid any stability dramas right from the start, I had attached a generous sized plastic drogue from the tail end of the kite.
Being a standard 10-cell design, the bridle was just a short loop from the top and bottom of the uppermost cell. With the short upper leg of the bridle coming away from the dowel rod at right-angles, the kite seemed willing enough to climb with plenty of wind pressure in the sails.
This first prototype was an attempt to combine a very short materials list with ease of construction and assembly. Like any other of my Dowel designs. Having spent several hours making this kite, another much better idea came to mind later... A quicker, stronger and much easier construction method. Featuring flat boot-laces for the connectors and their reinforcements. You'll just have to wait for the e-book ;-)
After a little bumping around on the ground and probably less than a couple of minutes in the air, the current kite had already started to come apart. So here's what's going to happen...
The current kite will be taken apart completely, all the connectors replaced, rods slipped back into the sails and the resulting cells connected back into a kite. Whew! But it should be a solid fresh/strong wind kite when finished.
And don't forget, if you want to take a closer look at my other MBK designs...
The Big MBK E-book Bundle is a collection of printable PDF file downloads.