Multiple Kite Posts

These multiple kite posts are flight reports that describe outings involving more than one kite. For example, the weather might have changed and the back-up kite needed to come out! In other cases, testing was being done on two kites at once. Or, a few kites were put up just on a whim :-)

I trust there is plenty in here to educate, inform, and often entertain!

These short flight reports once appeared as posts in the site-blog page, although that page is no longer present on this site. Below, the latest posts come first. Just scroll down and stop at any heading that appeals :-)

---

Indoor Sled Vs Diamond

After a side-by-side launch of the latest Indoor Sled and Indoor Diamond yesterday, the diamond seemed to have the edge in performance.

Today, I took pains to make sure about that and ended up hotrodding the sled a little more. The first Indoor Sled prototype flew fine but clearly needed more tow speed than the diamond. One kite flew from each hand, on 1 meter (3 feet) of thread, through the middle of our house :-) Having perfected the diamond, it's going to be the gold standard for performance for all the subsequent indoor designs.

In comparison, the second prototype sled had much more effective sail-area, although the width when laid flat was just a couple of centimeters more. The spars were kept at the original width but shifted further apart and made longer to achieve increased sail area. But as already mentioned, the diamond still had the edge.

Regarding test number 1 today ... I simply towed the two kites side by side through our small three-bedroom house. While the sled held a horizontal line-angle, the diamond spent most of its flight at a positive line-angle. So that was a fairly clear result. But just to be sure, I tried something else.

Test number 2 involved a launch from the floor followed by a minimum-speed flight through the living room until I could go no further in that direction. The flight was timed by counting ticks of the living-room clock. Liftoff was timed to coincide with a tick of the clock. The diamond was tried first and could consistently stay in the air for nine seconds. However, the sled could never get past eight seconds. Again, it was a clear result.

So it was decided to trim down the spars of the sled by just 1 mm of width! Somehow, I managed to remove the spars from the sail. It helped that I make a point of not wrapping tape around the sail edges, otherwise the tape would be nearly impossible to remove. By marking dots along one side of each spar it was possible to carefully snip off about 1 mm all along the length, before retaping to the sail.

Voila! The sled now averaged close to nine seconds in the air during the tow test. That would do! Oh, one last thing—a quick check was made to ensure the kite would still stay in shape at the redline tow speed of 6 kph. It did, and more, as indicated by the Windtronic meter being held in my towing hand.

Tale of Twin Drogues

Well, there weren't actually two drogues on the same kite, but two drogued diamonds were flying side by side on separate lines.

The idea was to test the effectiveness of a new Tyvek drogue. Yesterday didn't work out (due to light wind) and today was nearly the same story. However, with both kites out on generous lengths of line, they both stayed up long enough for a comparison.

Although comparing the effect of the drogues on identical kites was the main idea, it turned out that the two sails flew rather differently as well! One kite was spanking new and unpainted while the other was older with a half painted and probably slightly stretched sail. This older kite also had a glued horizontal-spar fitting which meant the sail could not be adjusted tight like the newer kite.

It took some time to get the older kite up and away with thermal gusts coming through at irregular intervals. Without at least 150 feet or so clearance from the ground there was little chance of the kite staying up. From a high height, the kite had just enough time to catch the next gust by the time it sank to ground level!

In comparison, the new all-white kite/drogue combo soared high easily—and stayed up there most of the time. This was interesting, since the new drogue was definitely heavier than the plastic one on the older kite. Aerodynamic efficiency well and truly trumped the extra weight! The weight would be a boon for train flying, helping to keep the drogue away from the flying line. As if to prove this, today I was able to observe the kite in freefall on its face during lulls, but it was unable to catch up with the drogue below!

Despite the difficulty in getting a clear comparison between the two drogues, the new Tyvek model seemed to have ample stabilizing effect. With the Adelaide International Kite Festival coming up I was also pleased to see that the sail/drogue combination looked good! The white Tyvek windsock is significantly slimmer but a little longer than the plastic one. It's also on a slightly longer tether.

So, I'd call today's outing a success. Now to charge ahead and prepare several more Tyvek drogues for the festival display.

I'm Retiring

Gotcha ;-) I'm retiring the Dowel Sode and the Dowel Sled for now, since the sails of cheap garbage bag plastic are very brittle from UV exposure. The kites have had nearly a decade of flying!

After finding the kites in our shed, some of the tip tapes were replaced with packing tape. Such was the condition of the sail plastic that I spent just as much time repairing damage that occurred while I worked! With the slightest tension applied, areas would sudden part along straight lines.

Anyway, the kites did fly today. Strangely, the big sled flew fine when it was new, but in recent years it has been most unreliable, tending to collapse far too easily. A bamboo skewer down the middle from the leading edge helped for a while— that is, for a few years. And today I taped along the leading edge with packing tape to provide additional resistance to the edge curling under. But perhaps sun exposure has dried out the wood and maybe even reduced the volume of plastic, making the kite somewhat lighter. Hence the kite accelerates faster and claps hands as simple sleds do when pushed too hard!

So, in fairly ideal light winds today, the sled just refused to stay up for long. After half a minute or so on 30 meters (100 feet) of line, down it would come as a "bag of washing." I might try a new sail made from somewhat heavier plastic. A loop tail is a sure-fire solution. That's not so much from a stability standpoint, but it tames the sudden forward acceleration.

The Dowel Sode did much better. By now the breeze had increased to 12 kph gusting to 20 kph. But this was still within range for the sode kite.

There was one small problem though. Immediately after launch, a tear appeared along the taped edging of one wingtip. As expected, this put the kite out of balance. For several minutes the Dowel Sode struggled on, leaning heavily to one side. Eventually the kite did a wide half-loop, suddenly popping upright within a few feet of the grassy ground. There wasn't much point in continuing so I packed both kites away and left the field.

It was a slightly disappointing outing but I guess every perishable physical object has a use-by date!

Sled and Roller Rise

On the way to the field, trees and bushes seemed to be indicating a lot less than the expected wind strength.

On getting out of the car, it still didn't seem worth taking out the Multi-Dowel Box kite. So the red Tyvek roller was selected instead. Also, in my carry-bag, there was the Soft Sled and MBK Parachute which together would cover a broad range of wind speeds.

First up was the Soft Sled on 30 meters (100 feet) of 20-pound Dacron. The kite never looked like coming down and absorbed the fresher gusts with ease. Yes, the wind had started to pick up! I realized the big box would have had a chance after all. However, at this location it was a bit of a walk back to the car, so the box kite stayed put.

With the sled doing well, I considered putting up the roller. But this kite had a history of getting damaged sail-tethers in moderate wind. So I waited for a while.

The conditions were getting less sunny with marbled mid-level cloud starting to filter out the sunlight. In theory, the gustiness and perhaps the overall breeze strength would die down somewhat.

Having got some video of the sled it was time to let it up higher. Soon, 90 meters (300 feet) of line was out and the bright-orange kite continued pulling hard and flying steep most of the time. In lighter periods, the sled would take on its characteristic slow waggle.

Eventually, the roller was rigged and soon it soared above the field. The rather uncomfortable wind speeds often pushed the kite to the left but it always recovered and returned to a 60-degree line angle. The tethers held, despite a very healthy tension in the 50-pound flying line.

Overall, the wind speeds did eventually moderate somewhat. But fresher periods still came through occasionally and tested the roller!

With two kites up on 300 feet of line and one on a small block-winder, it was going to take a while to bring them all down.

The roller provided a bit of excitement when turbulence from trees upwind caused a sudden dive at the ground. I reacted by pushing the winder at the kite, just in time, and the contact with the earth was soft.

It was a good outing, all in all!

Paper Kites Cavort

Did you like my corny headline? At least you're here ;-)

The purpose of today's outing was twofold—to log some more time on the Paper Sled and to test the Paper Diamond with more dihedral.

First up was the sled, which went straight up on some almost moderate gusts. But it was a warm, thermal-filled sky and so the breeze came through in waves. It would be gentle to moderate for a few minutes then light to gentle for another few minutes. Of course, the little sled was inevitably shot down during the latter cycle!

While this was going on, I put up the Paper Diamond on quite a few meters of line. Apart from a small imbalance to the left, the plain-paper kite flew admirably.

At the size it is, the diamond's paper sail formed an almost solid surface like a model aircraft wing carved from balsa wood or foam. Despite being much heavier than traditional kite-sail material, the little diamond had no trouble going to quite high line-angles. Amazing! I think this and following Paper Series designs are really going to rock in the gentle to moderate wind-speed range.

At this point I probably should have moved to a bigger field. Then, all 120 meters (400 feet) of thread could have been let out for the sled. But instead, I persisted and finally managed to log a 5 minute and two 10-minute flights. In every case, the kite simply sank out in slow air—all the way from about 150 feet off the ground.

For some reason, magpies seem to be particularly attracted to the Paper Sled. At one point I counted 10 of the black-and-white birds. Almost motionless, they were just standing around peering at the kite as it lay on the grass. Eerie!

Spineless Diamond, Soaring Sled

No, it's not the latest kiting kung fu movie—rather, the latest Paper Kites expedition.

Winds were gentle and only just gusting into the moderate range, down at the reserve. First up was the diamond prototype with a revised horizontal spar. The first spar allowed the sail tips to fold back!

The Paper Diamond proved easy to launch in the gusts that came through, with no problems at all with the horizontal spars this time. However, once high enough to catch the full force of the breeze, the kite began to exhibit a peculiar bobbing motion. Oh, that must be the the lack of a third bridle-leg I thought. But there was more to it.

The bobbing was quite cyclic at times, which reminded me of what deltas do when they have a weak spine! Yep, that would almost certainly be the problem. An inadequate vertical spar was flexing excessively under load.

So, the diamond was placed back in the car and the Paper Sled pulled out. This was a bit risky, since there was barely enough consistent breeze. Surprisingly, the sled ended up flying very high on two separate flights.

Thermal activity was around. The flip side to getting great height was the lulls and areas of sinking air that came through. This was enough to down a not-so-light sled kite in less than a minute!

The first flight had an interesting interlude when the kite line almost brushed a tall tree, with the kite struggling for height while drifting sideways. Touching the line would end the timing for the flight, so I resisted the urge to "work the line." After half a minute or so the sled crept back up again, and the flight continued for several more minutes—a 10-minute flight all up.

Flight number two saw the Paper Sled catch a quite strong patch of lift. Stepping out of some leafy shade, I looked up and couldn't believe the line angle! Really, there's no kite of modest performance that a decent thermal can't fix :-)

The next outing might be down at the beach, to get some closeup photos of the sled. I'll also test a diamond that hopefully will exhibit a bit of backbone.

Paper Sled and Diamond Dance

This was a slightly risky proposition, taking out paper kites with small patches of rain on the radar! But the patches of approaching light rain were dissipating, so out I went.

After the usual fiddling about in wind shadow, the Paper Sled finally found enough height and line length at the right moment. The newly minted #2 (made in colored sheets of A4) toiled upward on a tight polyester thread.

All-paper winders are also being developed, just to be consistent. The winder paired with this Paper Sled had a total of 120 meters (400 feet) of sewing thread wound on. I'll buy some more for my wife later ;-)

Leaving a few turns on the winder for safety, the line was passed under my gear bag. It held OK, with the winder jammed up against the upwind side of the bag. And there it was—a good 35 degrees of angle with the kite quite steady up at 200 feet off the grass. And perhaps it would go 50 feet more when rising air and fresher breeze strengths came through.

While the MBK Paper Sled did its thing up high, it was time to test the Paper Diamond #1. Earlier tests in the backyard had established that single-line bridles would not be practical in moderate winds. Not surprised? Neither was I really. Paper and tape has its limits. So, to drastically reduce the stresses on the horizontal spar, a simple two-leg bridle was tried.

The diamond lifted off with greater ease than the sled, which was surprising. However, the horizontal spar failed at the bridle attachment-points whenever the wind gusted. No problem—a bit of extra paper and tape at just the right spots will fix it. It's a much easier problem to solve than making a 1-line bridle work! A little extra tail will be needed too.

After 15 minutes in the air, the sled came down. This was possibly due to a bridle line finding its way around an upper corner of the sail in rough air. No damage was evident, and the kite sailed straight back up to 200 feet after one false start. This second flight lasted for 25 minutes—almost 10 of which were during the laborious wind-in of thread!

Some Kites Just Need the Beach

The local kite club bought a load of second hand gear—including kites—from interstate some months ago.

With the power supposedly being cut sometime between 8 am and 3 pm today, it was an opportunity to do something offline. Several large kites from Queensland were lying packed away in the shed. It was time to pull out one or two and see what condition they were in—and, possibly, get one in the air.

The first craft to be unrolled and rigged was a large single-liner with two bowed horizontal spars and several battens. Interesting! The outline was an odd low-aspect-ratio shape—nothing standard like a diamond or rokkaku. The owner had a huge amount of bow in the lower spar but I guess he did it in response to the kite's behavior in the air. In fact, a small loop knot had been tied into the bow line to pull even more curvature into the fiberglass tube. Only the horizontal spars had been removed from the sail to allow the kite to be packed away.

Two tails were included with the kite.

One tail was a series of panels that formed a long rectangular shape. Thin fiberglass rods were arranged horizontally at regular intervals to hold the material flat.

The other tail was a series of diamonds, arranged nose to tail. Each diamond shape had its own little horizontal spar. Like the big long rectangle, the whole thing just rolled up for storage.

I took the kite down to a local reserve.

After the breeze picked up, it proved too much for my super-light-wind Dowel Diamond. So, the big battened kite was rigged over some dry leaves and twigs, away from the damp grass. With just the rectangular tail attached, the colorful kite seemed a little too unstable to risk flying it high. So, after attaching the nose-to-tail diamonds as well, up the craft went for a more full-blooded attempt.

To cut a long story short as they say—the big kite didn't cope well with inland gusty air. The front end would twist and luff occasionally, sometimes coming close to pulling the kite into a dive. Eventually, that's exactly what happened—a nose-over followed by a steep dive into a wet section of the field. The nose pocket buried itself 8 cm (3 inches) into the mud. At least that might have prevented any damage!

Despite this experience, I'm confident that this kite will behave itself in a smooth sea breeze. Anything in the gentle-to-moderate ranges should keep this kite up. And it does look good in the air.

 

 

 

---