September 3, 2008 20:50 - Rokkaku Kite - In-flight Structural Failure!
Today Aren and I headed out intending to fly the 2-Skewer Rok, since the breeze seemed fairly gentle around our house. However, by the time we had parked at the Wilfred Taylor Reserve, it was obvious that the breeze was probably too fresh for the Rokkaku. Hence it was a good thing we had brought the 2-Skewer Barn Door as a backup! After putting Aren in the pram and attaching the 150 meter line, we headed out to near the center of the main grassed area.
The 2-Skewer Barn Door kite went up in what was a perfect wind strength for it. Very soon, it was flying steadily with 100 meters of line let out. At this height, the breeze was a bit stiffer. There were a couple of forced landings when the breeze was strong enough to force the barn door into diving to the left. Then, all of a sudden, I noticed that the kite was heading way off to the right. Lower and lower it got, going sideways through the air like a fish slowly swimming across its fish tank! Strange, I thought, it should correct any moment now, and head back towards the center. But it didn't, finally taking a dive into the car park. It missed my car and another parked car by just a few meters!
This is yet another incident that brings home the truth that it doesn't matter what you think your skills are like, and how reliable the kite has been in the past, you always have to assume it could go down unexpectedly! In this case, I probably had 4 or 5 too many meters of line out to be totally sure of staying out of trouble.
On a close look, I first noticed a big wrinkle in the sail near the top of one of the diagonal spars. My first thought was that the spar was damaged from the fast dive into the ashphalt. But it wasn't that bad, since it was just the electrical tape spar cap that had come loose. Somehow, the tail was still attached by sheer friction. I slid it back up the spar a centimeter or 2 and re-attached the tape, pulling the sail tight. Wonderful stuff electrical tape, it re-sticks so well! Just as a precaution, I also moved the towing point forward a bit since the wind was now quite fresh.
After this mini-drama, we had fun flying the Barn Door on 100 meters of line again, from the center of the main grassed area. Getting bored with this, I decided to move much further upwind. The Barn Door coped with the wind speed plus the pram towing speed quite well...
On the other side of a large grassy hump that defined the edge of the main area, we stopped and parked the pram. I started letting out line, and each time I stopped, a little voice would encourage me to let out a bit more :-) So, the kite ended up flying on close to its full length of 150 meters of 20 pound line. Straight downwind, there was plenty of room, but there was not nearly so much on either side, so I was prepared to run quickly cross-wind in either direction if the kite got in trouble again.
With the wind stronger than the ideal for this kite, it was maintaining about a 45 degree angle from the horizontal. Although there was a fair amount of tension in the line, there was still a fair amount of sag due to the sheer length of it. There was some thermal activity around, but generally, the wind was much less gusty than usual. Hence the barn door just hung up there, slowly shifting this way and that, and gaining or losing height as patches of rising air came through. The East South-Easterly breeze was quite cold, by Adelaide standards anyway!
I encouraged Aren to hold the flying line a few times. However, the tension was a bit much for him due to the wind strength. It wasn't much fun for the little tacker on this occasion! It was time to pack up.
In order to stay close to the pram with my young son, I tried a new technique to bring the kite down without winding the line on under tension. All I did was drop the winder and bring the line in hand-over-hand, laying it out on the grass in the cross-wind direction. After laying down line like this, going across and back several times, the kite was down and I was never more than 10 or 15 meters from Aren. After laying the kite on its back, with its tail tucked under the trailing edge to keep it stuck on the ground, I wound all the line onto the winder. Then it was time to go back to the car.
Aren had been demanding the Rokkaku earlier, so I thought I would give it a try even though the breeze was rather fresh. I think it's his favorite kite right now! Sure enough, the Rok just couldn't cope, distorting horribly in the stronger gusts and looping into the ground. Never mind, at least we flew something today...
September 6, 2008 20:57 - Barn Door Kite Flies Low For The Camera
This won't be one of our longer posts, since we just dropped in briefly to the reserve near the school in Old Reynella to get some video footage of the Barn Door kite. First up, I just put it up for a couple of short flights on just a few meters of line. This wasn't very satisfactory because it kept landing in the lulls! Light and variable winds at ground level.
However, a 3rd flight on maybe 25 meters of line or so was more successful, and it gave me 50 seconds or so of footage from which to edit out my standard 20 second clip for the Web page. At this line length, I had to zoom in to almost 4x to get the kite and its tail to fill enough of the viewfinder. As you can see in the video, the kite came down in a lull but then began to climb again in the next gust. No-one was flying it, I just had the winder under my foot in the grass!
The weather was sunny even though the air was cool. With cumulus clouds popping in the distance, and particularly over the hills to the East, I expected conditions to be rather 'thermally' higher up. Surprisingly, when I let the Barn Door right up to about 300 feet altitude, the air was glassy smooth! The towing point was a touch too far back, so the kite never got much above a 45 degree angle or so, but it was a unique experience to see it just sitting there, drifting just a little left and right with changes in the wind direction. Smooth winds around here are rare, even in Winter.
After a relaxing few minutes of flying the kite up high, it was time to leave, so I gave my wife the task of winding on line. Meanwhile, I pulled the kite down hand-over-hand so the line went onto the winder without any tension. With the kite at about 10 meters away, the soft rustle of the black garbage bag tail was just audible. To me anyway - I'm sure my little 2 1/2 year old Aren heard it much sooner!
The next video to go up will probably be of the 2-Skewer Delta which I'm just designing and building right now! Could be a few days though...
September 16, 2008 16:57 - New 2-Skewer Delta Kite - 90 Degree Line Angle!
Well, briefly, as a patch of rising air came through of course! But it was a nice moment after taking the delta out for the first time, and seeing it go directly overhead on 50 meters of line. We were at the reserve near the school.
These deltas can be fussy if the design isn't quite right, so I was pleased that it behaved itself reasonably well. Mind you, it needed a short length of tail to cope with the gusty air. We were hoping for another tail-less kite after achieving this with the Rokkaku. I still think this design is capable, but it needs a bit more dihedral, a lighter sail and smooth light winds. We'll try all that one day.
The conditions were a bit odd. Dead calm periods at ground level, with very fresh gusts above 50 feet or so! Enough to move medium sized branches around. Also, large variations in wind direction. Well, that has to be thermals doesn't it. Indeed, while the kite was out on 50 meters of line and climbing high, a small soaring bird appeared and began to thermal upwards. The bird approached at perhaps 3 times the height of the kite, but then climbed much higher towards the thick gray cloud cover overhead, slightly downwind of the kite.
I enjoyed a few minutes of seeing this latest creation doing its thing, against a backdrop of thick cloud and hazy blue patches. Sometimes, the delta struggled in the stronger gusts, porpoising rapidly up and down as it strained against the wind and picked up speed. Actually, I once saw the kite do this from behind its tail, while my wife did the flying far upwind of me. The kite was flapping vigorously! Not just the trailing edge, but the entire wing was flapping like a bird! A few times the orange delta was forced into a wide loop or long dive. It was fun to release tension on the line, see the kite stabilize itself immediately, and settle into another long climb back up.
Everything that happened today backed up what I read somewhere about single-line deltas - the best wind speed to fly them is just strong enough to get them climbing. Also, deltas always go unstable with too much wind speed. For a home-made delta with a slightly heavy sail (like this one!), this adds up to a somewhat limited wind range. But when conditions are right, you can still have hours of fun!
September 18, 2008 20:56 - 2-Skewer Delta Breaks Altitude Record
Well, it's own altitude record that is, and that wasn't hard since it's previous flight was the first test flight! Anyway, it was great to see the orange 2-Skewer Delta soaring around high up in gusty air with the occasional thermal boost. On arriving, we made our way to near the center of the Wilfred Taylor Reserve, since I wasn't clear on the wind direction. It seemed to be mainly from the West. The hand launch was super-easy, with the delta going up steadily like a lift. Line flew off the 150 meter winder, as I regulated it between finger and thumb. No need for a glove since this kite doesn't have a lot of sail area.
Once the kite was well above tree height, we started slowly moving backwards upwind, letting more line out. Soon there came this freakishly strong series of gusts, and the poor delta just couldn't cope. It ended up on the ground after narrowly missing some trees. In fact it disappeared altogether, since it was on the other side of a hump near the edge of the reserve. Just before it landed, I noticed the entire line of trees just behind it were being battered with very fresh wind. Where we were standing, less than 100 meters away, there really wasn't much happening at all! The kite must have copped the edge of the biggest thermal of the hour.
Pulling the line taut, I dragged the kite into view and stood it on its nose, waiting for a break in the wind. When the break came, it was fairly easy to flop the kite forward on its face, swivel it into wind with another pull on the line, and then pop it off the grass and into a long, fast climb back up to 50 meters or so.
After this, we continued moving upwind until finally we were right at one edge of the reserve. It became clear that the wind direction up high was more from the south, which was a bit inconvenient since it gave the kite less room. I was flying basically across the width of the reserve rather than down its considerable length. For this reason I wasn't able to safely let out all 150 meters of line. I guess about 120 meters were out.
The kite was still encountering wind that was a bit strong for it from time to time, so it covered a lot of sky. Several times it went into a vertical dive until slower moving air gave it a breather and let it recover. Most of the time however, the delta flew smoothly, between 50 and 60 degrees of line angle. Remember, this is probably the smallest 2-skewer kite, flying on more than 100 meters of line which had a fair amount of sag in it.
A bit of thermal assistance did pump the kite up to around 75 degrees at one point. Cool! It meandered around lazily, gliding like a paper plane for a while, before drifting back downwind. Eventually it was time to leave so I brought the kite down in stages, winding onto the winder in periods where the line tension was low.
An enjoyable flight! Makes me keen to start on a bigger delta sometime...
September 22, 2008 13:32 - Tree Leaps Out And Grabs Delta Kite
But it wasn't all bad! Read on... After going for a walk beside the sea at Glenelg, we were going to fly a kite from the beach, late in the afternoon. However, the tide was in and the only sandy stretches had too many people to safely fly at any reasonable height. Actually, we did see a couple of kites flying. A small sled and a fairly small diamond. Both colorful and, I'd say, shop bought. They were flying at less than 10 meters off the sand, which was sensible considering the number of people around.
However, it's just occurred to me that we probably fly our MBK kites much higher than most beach goers fly theirs. If you read this blog much you'll know my liking for nudging the legal altitude limit as often as possible!
We had no idea what the wind was going to be like, so had brought along three 2-skewer kites to cover all wind speeds. The Sode for very light breezes. The Delta for light to moderate. The Barn Door for moderate to fresh. Nothing will stop the flying!
We got around the lack of beach space by just dropping in at one of our regular flying spots on our way back home. The reserve near the school in Old Reynella. I walked out to near the middle of the field and attached the 150 meter line to the Delta. The kite of the month and therefore the favorite! There was very little breeze down low, but it wasn't hard to urge the Delta up a bit higher where it started to contact a smooth Northerly breeze. Just like down at the beach.
Quickly, I had more than 100 meters of line out and the Delta was doing fine, although showing signs of being near the top of its wind range. Yep, the breeze was rather fresh up there around 70 - 80 meters above ground! The Delta pulled very firmly on the 20 pound nylon line, and finally started to lean way over to the right. Mmmm, those trees could be a bit close... Ummm kite diving... better... pull in line... RIGHT NOW pulling, pulling... ooops too late! At least I started pulling in early enough so that the kite flew into the upwind side of the tree.
This is an honest blog. After all my preaching about making sure there is room in case of the unexpected, what happens... I fly the Delta into a tall tree on its 3rd outing! Bother, blast and other mild family-friendly expletives...
OK, what's done is done. I tugged at the line to see if the kite would just pop out. Nope. Reeling in most of the line, I approached the tree and tried another angle. The kite slipped down, and it was clear the line was around a single small twig. I pulled hard, expecting to break something, but thankfully the twig snapped and the kite floated down in one piece!
Soon the Delta was in the air again, and I backed off right into the far corner of the field to avoid a repeat performance. Even this time, I didn't get all 150 meters of line out since the wind was too fresh up high. Once or twice the Delta did an enormous loop to the right before recovering. However, it was flying with a tail that was only twice the length of the kite itself, so that was pleasing.
With all the tension in the line I decided against just winding it straight on. Instead, it was easy to walk out to the kite, bringing down the line as I went. With the kite in the grass, I walked back to the winder, wound it all on and took the kite back to the car. So glad it wasn't lost after the drama in the tall trees!
September 29, 2008 10:29 - Delta Kite Rides Gale Without Tail
OK, 2 slight exaggerations there. Hey, it rhymed! Firstly, the breeze was blustery and fresh, down at the Holden Hill reserve off NE Road. Not quite gale force though. Secondly, I experimented with removing a loop of tail plastic. This left the 2-Skewer Delta with just 1 loop, which is about as long as the kite itself. Although the delta then tended to loop tighter in some situations, it seemed pretty much as stable as usual when flying in a patch of smooth air. I think the main reason for this success was the small additional patches of tape I added to the left spar, to balance the kite. (After taking it home after its 1st flying session I discovered the right wing was heavier.) Perhaps deltas are a little more sensitive to balance in this way than diamonds and Roks and so on.
To start with, the delta was on about 30 meters of line. It's a small reserve, and I was still playing chicken with some of the trees... A couple of times, gusts accelerated the kite upwind. Its inertia carried it just past vertical! Never seen that before.
With the fresh breeze, the delta got quite a workout, often porpoising and wing-flapping as described in earlier posts! But being nicely balanced, it gamely managed to stay in the air for most of the time. Actually, the leading edge spars were flexing inwards and outwards behind the spreader. This gave the impression of flapping because the sail would billow up and down as it went slack and then tight again. All very quick mind you! About 5 times per second I would guess.
The couple of times the kite did end up on the ground, it was easily re-launched from where I was standing. The usual strong-wind technique. Pull it up on its nose, wait for a lull, topple it over onto its face, drag the nose into wind then pop it off the deck. I quite enjoy doing this! Sometimes you have to use a little finesse otherwise the kite can shoot sideways and curve straight back into the ground again. Also, if the wind is that strong, you might have to walk towards the kite or let out line as it climbs, to keep it climbing straight.
Moving down the reserve a bit, I found some more room and let out all 50 meters of line. Because of the wind strength, the kite didn't get much chance to move up to a really steep flying line angle on this length of line.
Eventually, a squall came through. First clue was a sudden increase in overall wind speed. Then, less than half a minute later, just the tiniest flecks of rain. Oops, time to bring the kite down immediately. I dropped the winder and walked towards the kite, pulling it down as I went. Amazingly, short tail and all, it kept flying at a high angle until it was down.
After the squall passed, we pulled out the 2-Skewer Barn Door and gave it a bit of a fly on just 20 meters or so of line. This kite doesn't mind a fair bit of breeze. May, my wife, had a fly for a few minutes while I watched Aren on the play equipment. No kite flying for him today, since conditions weren't really suitable.