October 7, 2008 13:57 - Kite Winder Testing Success
If you've kept an eye on the What's New section of the site, you will have noticed a new page on the MBK150 Kite Winder. We went out yesterday to the Wilfred Taylor Reserve to give it a whirl. The winds were fresh and cool, perfect for flying a moderate wind kite and seeing how easily line could be fed off the winder. The right kite for the day was definitely the 2-Skewer Barn Door kite. It handles fresh wind quite well.
It was interesting actually, watching the Barn Door fly near its limits. At a certain wind strength, it seemed to tend left. Aha! I thought, time to bring it down and shift that upper bridle knot a fraction. However, with a bit more wind strength, it went the other way! Intriguing. I can only conclude that 2 separate things were happening to the kite. For example, a slight imbalance in sail area might be sending it off to the left at a certain wind speed. But then, with even more wind speed, perhaps the spars begin to bend more on the other side, reducing the effective sail area on that side. Hence causing it to fly towards that side. One day I'm going to write some kite simulation software and get to the bottom of this kind of thing! Anyway, this sort of talk tends to bore people, so let's get back to the flying field... ;-)
OK, it was basically more of a photo / video session than a kite flying session. However, after we got all the imagery needed for the new website page, I just flew the kite up high for a while. Despite the cool conditions, thermal activity was evident now and again, pushing the bright orange 3-sticker kite up to fairly high line angles. With the wind coming almost straight across the field rather than along it, I was unable ... errrm ... make that unwilling to let the kite all the way up to 400 feet above ground. We all know what happens when you fly a kite on too much line in a confined space! All sorts of objects want to eat your kite... Been there before!
By the way, the video of the line coming off the winder turned out well! Despite me nearly getting a finger-burn from the line slipping out so quickly. If the kite was any bigger, you'd need a glove to fly it in such fresh wind.
Further down the field, a bunch of people were having fun with some flexible stunt kites. Plus an average-size sled. Predictably, they had heaps of trouble down low, with the rough air pouring into the field through the tree line. However, later on we noticed a nice big black steerable parafoil doing its stuff up high where the wind was stronger and smoother.
October 14, 2008 21:28 - New Roller Kite Flies Tail-less In Punishing Winds
Yes, another successful tail-less design! There's something intriguing about making and flying a kite without a tail. You spend your childhood exposed to tailed kites of various kinds, including the tailed flat diamond. The icon of Western kite flying which is etched on the brains of every school age child and most adults. The 2-Skewer Roller is my skewers-and-plastic version of the once quite popular Pearson Roller. Good directional stability is assured by means of fairly steep dihedral on the lower horizontal spar plus a small keel that is well behind the towing point.
As we left for the Wilfred Taylor Reserve, I knew the weather was really too rough for the Roller, particularly since the sail was made of a considerably lighter plastic than all the previous 2-Skewer kites. However, I just had to see if it needed any tail! As a precaution, I made sure the towing point was moved well forward. Optimistically, the 150 meter line was also brought along. It stayed in the car, as the new Roller shot skyward on the 50 meter test line. Another note on that sail plastic - it is a generic brand of garden bag which is single-ply. The more expensive garden bags use 2-ply. Great for stretch-resistance, but a bit heavy.
The kite struggled, with the trailing edge of the upper sail flapping violently. In the very strongest gusts, the spars would bend noticeably as the poor flimsy Roller dashed left and right at low altitude. However, during lulls, the general performance and stability was quite impressive. Can't wait to put this kite up near sunset one day, with the barest of breezes wafting in from the ocean!
After a while, I took the kite down to trim it to the right a bit. This worked OK, but eventually all the high-wind abuse took its toll with first one then both the tether lines pulling free from the lower horizontal spar! Amazingly, the kite continued to fly. Well, maybe not so amazingly, since now the effective sail area of the kite was reduced. Hence making the Roller cope better with the wind.
Bamboo is a great material. Despite hitting the ground hard a couple of times, and the vertical spar being twisted and bent alarmingly, the only repairs needed are those pulled-out tether lines.
Somewhere on the website, I commented that the Malaysian Wau kite has a similar configuration to the Roller. So it made me smile when my wife May said today that my kite 'looked like those Malaysian kites'! She's from Singapore, which is right on Malaysia's front door.
Hopefully we'll get out again soon when the wind is much lighter and finish off that construction web page with a video and a photo of launching the 2-Skewer Roller.
October 15, 2008 13:39 - Roller Kite Video In The Bag
With wind conditions light and variable on this sunny day, it was a perfect opportunity to go out with the 2-Skewer Roller kite. The 3 of us strolled down to the nearby Old Reynella reserve. Aren enjoyed the stroll from his pram. As soon as we arrived, we pulled out the Roller and put it up on a short line. May, my wife, took a few shots - one of which I cropped down and put near the end of the Roller kite construction page on the website.
After this, it was time to get some video. With maybe 20 or 25 meters of line out, the Roller floated and shifted around against a cloudy backdrop. I zoomed in quite a lot to get the kite to fill the frame more. Perfect! The resulting video was later chopped down to 20 seconds and posted at the top of the web page.
May then went off to play with Aren, while I stayed to play with the Roller kite! Conditions weren't perfect for it since occasionally stronger gusts came through and sent it to the ground. With no tail, it seems this kite is prone to long vertical dives from time to time, if it's near the top of its wind range.
Speaking of unintended landings, there was this Council worker doing maintenance on the play equipment while we were flying. A couple of times, the kite came to ground quite close to him. Both times, he obligingly approached the kite, intending to help me get it back in the air. Both times, I managed to re-launch just as he reached out for it! How was he to know I do this all the time... Ground launching is part of the fun!
Like the Rok and Delta, the Roller is very responsive to rising air. Some large thermals were about, as I discovered when the kite started sinking and would not respond to line pulling. I kept bringing it in, fast, and it kept sinking! Right up until it landed at my feet. It was then that I realized that the wind direction had almost completely reversed. I felt the tiniest breath of air on my face, while I was still facing the kite. No wonder the Roller wanted to come down!
In total contrast to this, a few minutes later the kite was floating way overhead on the full 50 meters of line. The line angle crept up to 80, 85, 90, 95 degrees. How's that - past vertical! The flying line bowed out in all sorts of directions. After wandering around for a few moments like this, the prevailing wind took over and the kite went back to its more usual 60 degrees or so.
The MBK 2-Skewer Roller is definitely a fun kite to fly in light wind and thermals!
October 24, 2008 13:56 - Roller Kite Soars In Almost Nil-Wind Thermals
At last things looked promising outside, after waiting several days for the windy conditions to subside. Almost blue skies and light winds. With the 2-Skewer Roller kite and 150 meter line stashed in the car, we headed off for the Wilfred Taylor Reserve. Aren accompanied me in the pram as we made our way to near the center of the grassed area. A moment later, after attaching the kite with a Lark's Head knot, the Roller was up ... and not doing very well. It kept looping to the left with the slightest amount of extra breeze.
On a previous trip here, the Roller was struggling in strong wind, and on one occasion hit the ground hard. The vertical spar bent horribly, but then sprang back. Good stuff, bamboo! However, did it spring back completely? I had my suspicions, since I had noticed a slight curve in the spar as the kite hung on the wall at home. Also, on its last outing, I had noticed a tendency to turn left occasionally, but it didn't seem too bad.
Well, I had to do something, and I had a feeling that tweaking one of the tether lines on the upper sail wasn't going to do much this time. In desperation, I took hold of the vertical spar with both hands, just above the glued joint, and bent it. Not quite enough to hear any cracking, but it seemed to leave a slight bend in the required direction.
Not really knowing what to expect, I launched again. Seconds later, there was the Roller, parked at a 60 degree angle and beautifully stable! Hey, on with the show! Gradually, we moved across the grass, letting more and more line out. The pale-orange translucent Roller was now behaving like a real light wind kite. With about 50 meters of line out, it started to float almost directly overhead in a small patch of lift, before settling back downwind a bit.
With around 100 meters of line out, the kite was just hanging there, sometimes descending slowly and sometimes climbing slowly in response to small changes in wind speed. Aren had a go, leaning out of his pram. To my amusement, he started pulling in line, then letting it out, then pulling it in again! Wow, working the line at age 2 3/4...
Finally a decent patch of rising air came through, and I was able to climb the kite almost vertically for another 40 or 50 meters. At this point, the trees downwind were likely to be a problem if anything went wrong, so we started backing up towards the car park. Some more rising air came through, so I used that too, to let out more line. Finally we arrived beside the car.
Eventually there it was, an almost empty winder with only a couple of loops left of the 150 meters (500 feet) of line..The 2-Skewer Roller doesn't have a lot of sail area compared with say, the Sode or Rokkaku, so at this line length it was hanging at about 40 to 45 degrees above the horizontal. However, yet another small thermal came through, and finally pumped the kite up to around 50 degrees. Even then, there was a fair amount of sag in the 20 pound Dacron line.
At this point it was at an altitude of around 350 feet above ground. At ground level, there was hardly any breeze to speak of. Beautiful light wind, thermaling weather! A perfect flight for the 2-Skewer Roller, letting it strut its stuff as a nice light wind flier. After a few minutes, with a toddler whining to go on the play equipment, I brought the kite down. It was just a matter of winding directly on to the winder since the tension was very slight. In any case, I stopped winding whenever the kite wanted to climb a little.
October 26, 2008 18:02 - 1-Skewer Box Kite Concept Flies!
This was at least the 3rd attempt to fly a little 1-skewer box kite that I whipped together recently. With a run of very windy days, I just couldn't get box kites off my mind! The weather down at the Wilfred Taylor Reserve was mild weather-wise, and very windy - and gusty. The strongest gusts were not quite gale-force, but strong enough to make the flying line whistle, without even much tension on it.
Because the kite was constructed on a whim, it ended up with crooked left-over skewers for spars and 2-ply orange garden plastic for sails. I knew it was going to take a lot of breeze to fly! From earlier attempts, I knew the tiny box kite required a fair amount of tail to be stable enough to get some height. Its chances of success were much better today, due to both the high wind strength and the extra tail.
Well, it flew! Only just. For a few seconds during one enormous gust, it hovered several meters off the ground at perhaps a 20 degree line angle. Not great, but good enough to inspire me to make another one with greater accuracy of construction, decent straight skewers, and much lighter sail plastic. Should be fun! And of course, the plans will end up on this website, if you would like to re-create it for yourself.
Now that we have a 1-Skewer Box design, guess what else is just around the corner... Yep, the 2-Skewer Box kite, which should require only moderate breezes to fly. However, the nice thing about traditional square box kites is the fact that you can take them out when it's literally blowing a gale outside!