Skewer Tetrahedral Kite Posts

This skewer tetrahedral kite has seen quite a bit of flying since it copes well with breezes that overpower my light-wind designs. Also, this tetra can just squeeze into the car without being disassembled. Larger tetras are magnificent in the air, but you spend a big chunk of time setting up and breaking down all those cells!

These short flight-reports once appeared in the site blog page, which is no longer present. Just scroll down and stop at any heading that appeals, below :-)

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Skewer Tetra on Taut Line

It was getting late in the afternoon and a smooth cool moderate breeze was blowing.

Tetra Terrific

... after a few tweaks on-field!

The breeze outside was somewhat less than forecast, but would support the 10-Cell Skewer Tetrahedral. Bamboo! Just in case of persistent low wind, the Red Roller was brought along as well.

The field I chose was suited to the prevailing westerly wind direction. However, that location can be a little tricky with a fairly sharp wind gradient over much of the field. In other words, the transition from insufficient breeze strength near the ground to sufficient can be rather sudden as the kite is urged up past 50 feet or so. It depends on the general wind strength too of course.

The first half hour was a yo-yo affair with rapid pull-ins and slide-outs of the line. Tetras don't accelerate upward very well, even with a decent yank on the line! It wasn't long before I was towing up on over half the field length of line. Long periods of slower air thwarted each attempt to stay up. No amount of fancy line-working can compensate for insufficient wind strength. On the other hand, gusty periods would have really pushed the roller!

Finally, with rain approaching in the distance, the breeze became more consistent and stronger. Launching right from my hand became effortless. It was satisfying to slowly let the line slip, maintaining a 20 or 30-degree climbout. With so much cloud about, the kite's position was clear against the detail of low cloud-cover.

A rainbow parakeet swiftly glided past in a shallow dive, making a subtle hiss, before it settled in a nearby tree.

Annoyingly, the tetra was spending much time on its side while up in the fresher air flow. So I took it down, tightened some panels on one side and tried again. That was better, but still more correction was required. Plus a loose joint needed to be retied. This time I pulled some of the main tail off and added it to one corner. Mmm. A bit more? So eventually I added some black plastic loops to the corner as well, and these really did the trick.

For another half hour or so I just enjoyed watching the kite fly steady and straight, on 120 meters (400 feet) of taut 50-pound Dacron. There seemed to be areas of weak lift and sink around too, so the kite on one occasion was boosted to 45 degrees of line angle. Hey, it's a tetra with baggy plastic panels ok? :-) Stronger rising air has pushed this kite to 60 or 70 degrees in the past.

A galah did a rerun of the parakeet's flight path but overflew the tree and continued on.

Eventually, the bamboo-and-plastic cellular sank to the ground in a lull and I took it back to the car. Less than an hour later, the rain arrived.

Tetra Tilts

Nothing had flown for a while and the weekend had arrived early, as it can do when you get older ;-)

Rain clouds hung around promising to clear as the Saturday afternoon wore on. The peak wind-speeds were well into the moderate range, according to the latest readings from the nearest weather station. Hence it was decided to pop both airworthy tetras in the car. The latest, most colorful tetra had suffered a broken spar at the kite festival last month.

Down at the reserve, dark clouds on the brink of dropping water seemed to coincide with much stronger wind gusts. Despite this, launching the MBK 10-Cell Tetrahedral kite took a number of attempts in the short-lived gusts down low. Up over 2000 feet, scrappy dark cloud scudded past, indicating brisk air. Higher still, mountains of white cumulus peeked through, brilliantly lit by the late-afternoon sun.

Soon after the tetra got out to 30 meters (100 feet) of line, it was clear that the kite had a pronounced tilt to the right. Never mind, I had come prepared with some extra lengths of tail plastic! After the next launch, the kite seemed over-corrected to the left :-| Hence the tail-let was shifted from the corner, one cell closer to the main tail. That seemed about right, helping the skewer-and-plastic craft soar up high. It did so for a while...

With the kite in improved trim, much more line could be let out. After flying about on 90 meters (300 feet) for a while, I decided the wind direction would allow for 120 meters (400 feet). Full use was being made of the field's length by this stage!

And so began a delightful long-and-high flight in the cool air. Up high, quite prolonged periods of fast air would still push the kite over, overcoming the effect of the tail-let. At other times the blue cellular was able to rise straight up and touch almost 40 degrees or so of line angle. In perfect trim it would make 40 degrees easily, no doubt. The wind direction in these cool conditions was rather constant, so it was the kite itself that would get forced out of station and later drift back to the left. Changes in line tension were quite sudden at times, indicating rough conditions. But it was nothing the 50-pound braided Dacron couldn't handle.

Finally it was time to end the flight, so I began winding in. Periods of reduced tension were the cue to wind faster, while heavy tension sometimes meant a complete pause. As the kite got lower, it began to be affected by the wind shadow of a large tree. That was a bonus of course! Finally the kite came to a soft landing on one side with several meters of line stretched across the grass.

Perhaps I'll shift that tail-let back out—but tear some length off the end to fine-tune the trim.

Tetra Tops Out

The 10-Cell Tetra, trimmed out and flying in smooth brisk air, topped out at a 45-degree flying angle over the sand.

So, it would appear that a lightly built tetrahedral does well on a towing point somewhat aft of where it is usually seen on traditional tetras. You know, those cellulars of yesteryear made of sturdy dowels, cotton sails, and (gasp!) metal fittings.

I had the Prusik knot fully 50% down the bridle loop. The loop was secured to each end of the spine of the topmost cell of my bamboo-skewer-and-plastic kite. The sail panels were in blue drop-sheet plastic, orange garden-bag plastic, and black garbage-bag plastic. That's about as colorful as you can get with mass-produced plastic :-|

Early on, with the sun obscured by thick cloud, the breeze registered 20 kph with gusts to 26 kph. That's a very comfortable range for most cellular kites.

While waiting for patches of brighter sunlight to drift closer from way upwind, I had several attempts to trim out a pronounced lean to the right. A length of light plastic tail from the left corner helped, but the real problem was mis-aligned cells. They're all like little rudders! After the third untie/re-tie of shoelace ties, on as many cells, things were looking much better in the air. The extra tail was left on for good measure.

At last some decent sunlight turned up and I made the most of the large blue hole in the sky, getting numerous camera shots from various angles. That was actually the purpose of the outing—to get the title-page shot and scenic shot for the up-coming e-book Making The MBK 10-Cell Tetrahedral Kite.

With closeup shots taken, more line was let out so the kite floated about 60 feet above the sand. Much more than that and it would be hard to frame up the scenic shots! Although the tide was well up, the wind direction was favorable, being SSW. Also, being a slightly onshore breeze there was plenty of sand over which to fly.

Meanwhile, the breeze seemed to freshen somewhat. Sure enough, with wind meter out, the speed measured 30 kph gusting to 35 within a minute or two! No wonder the tetra pitched over, touching a corner to the sand, as I brought the kite in. Fortunately nothing snapped.

Mission accomplished!

Tetra Weather—On and Off

The latest tetrahedral was out on the veranda overnight, while some glue dried on a mended skewer. Unfortunately, some strong wind blew a huge cardboard box against the kite and broke another skewer!

So, the colorful 10-Cell Skewer Tetrahedral kite was going to sit there for another day. Slow-drying glues are cheaper ;-)

This all happened yesterday and was the reason I had to pull out the older all-blue tetra prototype instead. Out at the field, the breeze didn't quite live up to the weather-station readings from only minutes before.

It seemed the wind speed was only occasionally up in the moderate range. This caused quite some delay as flight after flight ended prematurely. It was a struggle to get a good length of line out.

Finally, a good long gust got the kite away, high over the field. Extra tail had been added in anticipation of fresh gusts. That was just as well, since after a while some rain clouds passed close by ... bringing with them furious increases in gust strength. Instead of struggling to stay up, the kite was now being forced into huge loops to the right! Even so, the blue tetra spent plenty of time soaring about against the mainly monochrome cloudy backdrop—dark rain-filled patches right through to brilliant puffy whiteness. There were just a few small areas of blue sky.

With some video footage taken and time running short, the tetrahedral kite was slowly wound in. Perhaps I'll hang some tail off one side next time, to trim the kite out properly. Then we'll see what it can really do when the wind strength creeps into the fresh range!

Tetra Turns Tail

It was supposed to be a photo shoot for the latest tetra. This was a multicolored kite, built to illustrate an upcoming e-book.

Wind speeds were ideal, gusting over 30 kph down at the nearest beach. However, on arrival the tide was not ideal :-( That, plus the due-westerly wind direction provided very little sand over which to fly.

So I drove past and turned back, ending up at the large square Knox Park just a few kilometers inland. There were no surveyors this time so the orange, black, and blue kite was cleared for takeoff—so to speak.

Even out in the middle, conditions were extremely gusty. Brilliant sunshine kept getting replaced with dark shadow as the morning's rain clouds dispersed and drifted overhead. Photography was tricky since it was hard to get the kite to stay in the air long enough on a short line. No sooner was the camera out than the kite was either down or heading that way :-| And it wasn't for lack of wind, which sometimes generated leaf noise like a dull roar from the edges of the reserve.

The tail (made of very thin plastic) was tending to fold up on itself, which reduced its effectiveness as a drag producer. On top of that, the kite had a slight built-in turn to the right. These factors conspired to keep the flights rather short!

On more line, perhaps 30 meters or so, the colorful bamboo-and-plastic craft did finally climb high for a few minutes. A tied-on length of extra tail helped things along! It was decided that on another day the amount of tail would be tripled, simply by adding identical tails to either side of the central one. That is, all three would be attached near the tail end of the kite and from three different spots on the same bamboo-skewer cell frame. That should fix it!

So it wasn't the most memorable afternoon of tetrahedral-kite flying. By the look of the weather site, next Friday or Saturday could be suitable for another try.

10-Cell Tetra Tugs

Online weather was reporting an average wind speed just below the gentle range, but gusting strongly.

With those gusts, there was a chance the 10-cell tetrahedral kite would stay up. To be on the safe side, I also took the Dowel Box kite—the lighter one, not the Fresh Wind version.

Just as was happening around the house, out at the field the gusts were ferocious. The trees and bushes were being moved around. Even so, a lot of time was spent flying the kite at low line-angles, only to have it sink out during lulls. I tried shifting the towing point aft a little.

Finally, a prolonged mega-gust rolled through. Up went the tetra as if hitched to an elevator! Within a few minutes, I had 120 meters (400 feet) of 50-pound Dacron out. There wasn't a lot of sag either.

Puffy white cumulus clouds filled most of the sky.

Then followed a delightfully long and mostly high flight. Tetrahedrals pull smoothly due to their weight and very forward towing point. So instead of a "twitching fish" kind of feel, tension tended to creep up and down at various speeds. Strong thermal lift would loft the tetra up to around 40 degrees and well above 200 feet of altitude. Another time, I felt cool air coming through the trees. Sure enough, the kite just sat stubbornly at a mere 20 degrees or so, pulling strongly but going nowhere in the rapidly sinking air!

The presence of thermals also shifted the wind direction around a lot from minute to minute. While taking some video from beneath the shade of a tree, the shot ended when the kite steadily moved sideways and then disappeared behind some foliage.

School pickup loomed, so the 10-Cell Skewer Tetrahedral kite was slowly brought down. The winder was a very solid wooden one and it's never had a problem with line being wound straight on under tension.

Tetra Terrific After Trials

As usual, the 10-cell Tetrahedral was a pain to launch inland.

In fact, I had intended to fly at the beach, but there was a due-westerly breeze. This meant a very limited flying space was available, between rocks and a wet place :-)

So, the local archery range was selected instead. This time, no arrows were flying so the kite was soon in the air. Again and again, short hopeful hops were the best that could be achieved.

Large thermals were around and quite fresh gusts came through on a regular basis. However, it was a race against time to let out enough line and gain enough height before that sinking feeling started all over again :-( No amount of fancy line-working was working, if you get my drift.

One corner of the kite came completely undone when a shoelace bow worked loose and disappeared somewhere on a dusty patch of ground. However, while returning to the kite with a pair of scissors I managed to spot the missing lace. It was time to try again.

To cut a long story short, I did eventually get 60 meters (200 feet) of line out. The kite was away! With all the rising, rough, and descending air, flying the tetra was remarkably similar to fighting to keep a light-wind kite in the air on an almost-calm day.

Line tension was going up and down. There was much slipping-out and pulling-in of the flying line to maximize air time. The experience was remarkably similar to the light-wind scenario, except the wind speeds were 20 kph faster!

As one huge patch of lift came through, there was the very satisfying feeling of letting line out slowly for an extended period while seeing the kite hold a constant line angle. Out and out, up and up the blue tetrahedron went!

Floating around high up, the tetra would sometimes tilt from side to side in rough air as the edge of a strong lift-region approached. At other times the kite would sit low but pull hard in sinking air. Also, as thermals passed by on the left and right, the kite would get pushed sideways a lot as the wind direction shifted.

Finally, and most unusually, I had 150 meters (500 feet) of 50-pound Dacron in the air. However, being a little inefficient compared to flat kites, the 10-cell Skewer Tetrahedral was no more than 250 feet off the grass.

It was a magnificent flight to end with, after 40 frustrating minutes trying to "get away."

Skewer Tetra Sets Sail

The weather station online was indicating tetrahedral-friendly winds outside.

The 10-cell Skewer Tetra had only just been completed. Being sparred with bamboo, the kite was much lighter than the earlier dowel version in the same size. Hence I was confident to attach much less tail than was used for the Dowel Tetra. All other things being equal, lighter means steadier in the air!

Down at the huge square grounds of a local school, the moderate breeze was moving small branches around as the gusts came through. On a short line, the 10-cell tetrahedral immediately showed itself to be stable and willing to rise. However, tetras come down quickly in lulls, so a few more launch attempts were made. Much more line was used this time—about 30 meters (100 feet).

A couple of flights were spent to get the simple two-leg bridle adjusted.

Finally, some good consistent air pressure was found as the kite floated near the middle of the large field. I didn't waste any time letting line out to 60 meters (200 feet). However, even on this length, the kite was spending some time at rather low line-angles.

While there was some good tension I continued to let the line out to 90 meters (300 feet). The 50-pound Dacron felt about right for this kite. Even so, there was plenty of sag when the breeze strength dropped into the gentle range. That is, under 20 kph.

With the kite tied off to the substantial wooden railings, I took some video footage from various angles. The kite helped out by moving toward me and dropping low at times! It was satisfying seeing the kite steadily climb away again when the breeze freshened.

So, it was a quite successful outing with the new tetrahedral kite. This one is easy to land softly by using a tug on the line just before it touches.

 

 

 

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