June 10, 2008 15:02 - New Barn Door Braves Spar-Bending Breeze
From the weather report for today, we knew we had a brief window in which to get out and test the new 2-skewer barn door kite. On top of that, it was going to be very windy. Oh well, the 1-skewer barn doors did well in strong wind, so the new one should cope. Maybe...
Down at the Morphett Vale High School oval, I hitched the new 150 meter line to the MBK Barn Door and flew it around down low for a while. This was so May, my wife, could take a few pictures. After some fiddling with the bridle it finally behaved itself and shot skyward in the freshening breeze. Also, it shot to the left and to the right while struggling in the stronger gusts! As you can see in the photo, I added some extra tail to help the kite cope.
I could see a lot of flexing going on. As tension built up in the flying line, the normally straight sides of the sail became distinctly bowed. All 3 bamboo spars must have been bending considerably. It reminded me of our cheap stunt kite when its fiber-glass spars bend as you fly it in a very strong breeze!
The flexing had the effect of loosening the knots, unfortunately. Twice, the kite suddenly started spiraling to the right. Each time, I had to walk out to the kite on the ground and re-tie the upper right slip knot. These knots usually hold pretty well, but with the bamboo spars moving against one another and flexing, it was just too much.
Eventually, I couldn't resist flying the kite quite high, on maybe 80 to 100 meters of line. The poor kite took quite a battering, straining this way and that in the even faster flowing air higher up. A few times it even did a large complete loop, taking it to within just a few meters of the ground. At this height, the lower wind speed usually allowed the kite to recover by itself. On one occasion the kite needed a bit of help, so I quickly walked towards it to reduce tension in the line.
While winding in the line before we went home, we noticed low clouds scudding along at an amazing speed. It was definitely blowing a gale up there, or close to it. Medium sized branches in the trees were moving around. It will be fun to fly the MBK 2-Skewer Barn Door in a more moderate breeze!
June 13, 2008 21:05 - 2-Skewer Barn Door Kite Perfect Match For 20lb Line
Summer weather was forecast for later in the weekend but Aren and I couldn't resist taking the new 2-Skewer Barn Door kite for its 2nd outing. The sky was still 9/10 cloudy, with ominous dark patches here and there on the horizon. Conditions were pretty ideal down at the Old Reynella reserve though. A cool, gusty light to moderate breeze was moving the tree tops as we arrived. I launched the Barn Door without any extra tail and it behaved beautifully. Well, most of the time. Some strong gusts really tested its stability when it was down low and on its side, after being forced down in a large loop.
It's the middle of winter here so imagine my surprise when the kite kept floating up to 80+ degrees line angles with a taut 60 meters or so of line out! It must have been small patches of lift, since most times this was quickly followed by the kite sinking suddenly, sometimes almost tail-sliding back into its own tail! At other times the kite would race across the sky from right to left or vice versa. This reminded me of the flying characteristics of its smaller cousin, the MBK 1-Skewer Barn Door. This would happen when the wind was fairly constant and not quite strong enough to make it loop.
Aren had a chance to fly the barn Door too, from his pram. He gamely held on even when it pulled hard! With more sail area than the MBK 2-Skewer Diamond, this Barn Door is perfectly matched to our 20 pound flying line. I think when we get the chance to fly the 2-skewer Barn Door on our 150 meter line, it will still be able to pull most of the sag out of it.
The sun was nearly down at this point, so I hauled the kite in, managing to fly it right down to my feet. Call me lazy if you like. I call it getting the most out of a kite flying session! As it passed down through treetop height, it nearly sank to the grass a couple of times during lulls, before I towed it away from the ground and into the next gust.
June 17, 2008 18:46 - Striiiike 2! Bird Strike On Barn Door Kite Line
Yes, strike 2, when 3 unsuspecting birds flew too close to the flying line. I'm sure the baseball analogy won't be lost on you if you are from the U.S. or Canada! Actually it's a bad analogy since a strike is when you miss isn't it. Mmm better get back to kites...
The wife and small son were going for a bus ride so I took the opportunity to try the Wilfred Taylor Reserve in Morphett Vale for a change. This has quite a sizable rectangular grassed area with only low trees on 2 sides. After giving up on the MBK 2-Skewer Diamond, due to the quite strong wind, the new 2-Skewer Barn Door came out. This 3-sticker struggled too, despite extra tail being attached. However, there was some improvement after I shifted the towing point forward a centimeter or so.
A bird strike has happened before, which was also recorded in this blog. 'Strike 1'. However, a second bird strike was still pretty unexpected! I'm sure I felt a slight twitch in the line as one of the 3 birds appeared to make contact. All 3 took evasive action, before continuing on their way towards the West. Perhaps looking out for more inconsiderate kite fliers invading their airspace.
Since the breeze was moderate to strong, even the Barn Door came to ground a few times. No problem, I just re-launched straight from the grass. With its horizontal top edge, this seems to be a little trickier than with a diamond, but still do-able. As soon as it toppled over to one side, while being gently dragged, a firm tug popped it back into the air for a quick climb back up. This was fun with 100 meters of line out. A good way to startle nearby drivers or pedestrians! A bright colored kite rocketing up from no-where, with no kite flier in view. I was in a car park, right next to the field, to get those extra few meters of line length!
A lot of time was spent low, zipping great distances to the left or right before a slight drop in wind speed would allow it to recover and climb back up to a 45 - 55 degree angle. In any case, a fair amount of air time was spent near those maximum line angles. Since the wind was blowing across the field rather than along it, I wasn't able to get anywhere near the full 150 meters of line out. Just too risky with all the unscheduled landings! Today's flying was the highest this barn door has been so far, so that was satisfying.
June 19, 2008 21:33 - First MBK Kite Stack - The Diamond Plus Barn Door
It was a bit gusty outside, and seemed a bit strong for the diamond. Our house is situated halfway up a slope in a slightly hilly region of the suburb. So what, you ask... Over the past few months I have observed that wind speeds tend to be faster near the house than the wind speed just a kilometer or 2 away, over flatter ground. For example, there might be a very gentle breeze moving nearby fronds and tree leaves. However, on turning up at the flying field, it's practically calm! And so it turned out today.
On arriving at the Wilfred Taylor Reserve, the wind was not too strong at all. The breeze was ideal for both kites, although some of the gusts bordered on being too strong. That's typical of this area. Thermal activity all year round and very gusty breezes, whatever the average wind strength.
We soon had the barn door kite up, which indicated the wind direction. Then we moved around the edge of the reserve to find a spot that would give the kites the most room in case of an unexpected landing. By chance, the kite kept flying very close to the position of the sun. Half the time we couldn't see the kite itself, and had to look at the flying line to see how it was going! Hence, the kite's shadow was always flitting around not far from where we were standing.
My idea for today was to attempt to fly the barn door on the 50 meter test line then attach the diamond beneath it on another line. A 2-kite stack or train in other words. Never did anything like this before, so I was prepared for it to flop! The diamond had been prepared at home, with a short length of line tied around the point where the spars cross. Also, there was a simple overhand loop in the end to provide a large knot. Today would be a test of my 48 year old eyes, with no less than 3 tiny Larks Head knots to tie and untie at various times!
On the subject of the Larks Head - this very simple knot is amazing useful, since it holds a kite line with complete security under a lot of strain, but then is quite simple to release. Simple, but not necessarily easy with thin 20 pound line! I think I've finally got the knack, using a thumbnail to pinch the microscopic loop and pull it free. Another technique I experimented with was trying to pull the knot apart sideways with 2 thumbnails to loosen it, then go for the loop.
With the barn door flying high on its 50 meter line, I wrapped the line around my hand leaving the last meter or so free. Then it was just a matter of using the fingers of both hands to loop a Lark's Head over the knot on the attachment line from the diamond kite. Finally, I carefully freed my hand from the barn door's flying line and transferred the tension to the diamond's flying line.
With the barn door frolicking around high up and pulling strongly, I let out the diamond to about 10 or 15 meters. No room for any more than that, unfortunately, with the prevailing wind direction. First impression was that the flying line was under noticably more strain with 2 kites pulling at it! That's logical. If one more kite were to be added to the stack, the bottom one had better be on 40 pound line!
The diamond kept wrapping its tail around the flying line behind it. Several times I brought down the diamond by walking out to it, to unwrap the tail. Finally I figured a short tail would be less trouble, and simply looped the single tail around and tied its end to the tail end of the kite. This half-length tail worked pretty well, but it still managed to loop around the line once or twice. However, the diamond seemed to fly fairly normally while its tail was free. A strong gust once caused it to do a complete loop while the barn door flew on undisturbed, far above!
I was quite happy with the outcome, although couldn't help wondering how critical the position of attachment point is, on the lower kite. Today it must have been close enough, since the diamond seemed to hold a close to normal flying attitude while it was up. Its going to be fun to do this again, with maybe 100 meters of line below the lower kite.
Was kicking myself today for not bringing the camera. Have resolved to always bring it from now on!
June 21, 2008 22:56 - Revamped 1-Skewer Diamond Kite In Tow Tests
Tow Tests? Nothing fancy actually, I just had to tow the little diamond through our back yard to above roof height a few times to check the effectiveness of its tail. My standard construction techniques have finally sorted themselves out, so it was time to completely re-do the construction notes and photos for the MBK 1-Skewer Diamond Kite. The 1-skewer sled was done last month. See the pattern - one new kite as usual and one re-vamp of an old one each month. All in the interests of keeping things simple yet effective for new kite-builders.
With spars from the heavy batch of bamboo skewers, this little diamond won't be quite the light-air floater that the original one was. However, there was a bit of breeze about, and the kite hung up there above the roof for half a minute or so at a time. Rocking just a little from side to side as small diamonds do.
Lulls would bring the kite back down, sometimes to hit the roof! This was hard to avoid, since the 1-skewer kite doesn't have the beautiful stability and predictability of the 2-skewer version with dihedral. But not to worry. It wasn't the worse for wear after several roof re-launches! Interestingly, the small diamond still flew well despite having droplets of water on the sail and tail from our wet lawn. Try doing that with a paper kite!
A couple of days ago, I briefly flew the 1-skewer diamond up to about gutter height in the back yard, but it was obvious it needed more tail. Increasing the tail length from 4 skewer-lengths to 6 seems to have done the trick. The plans page and construction How To.. page were updated accordingly, so people don't end up with a kite which doesn't fly.
I might take it out again tomorrow and fly it on 50 meters of line if weather permits. Also, we need to get the launch photo for the bottom of the How To.. page. Aren, our 2 year old, might have a fly too, since this kite couldn't pull the skin off a rice pudding... The same can't be said of the diamond / barn door train that we flew the other day. I gave Aren a go, but he didn't have the strength to hold the line in one hand without it slipping or pulling free. He can handle the 2-skewer diamond on its own though.
June 24, 2008 19:41 - New 1-Skewer Diamond Kite Tested
We went out today to the Old Reynella reserve with the new 1-skewer diamond kite. However, nothing much went right!
The Prussik knot had loosened and lost one of its loops. Picking it apart and re-tying wasn't really an option out on the reserve without my reading glasses, so I just pulled it tight. Where-upon it ceased to become a sliding knot and just stuck fast in the wrong spot! OK, no problem, I'll just tie a small overhand loop in the bridle line to shift the towing point to somewhere near the correct position.
The kite still mis-behaved, not wanting to fly during the lulls but looping to the right when the breeze was strong enough to lift it! I tore off a little tail plastic and attached it to the left wing-tip to balance up the drag forces on the kite. This helped, and the kite made it 10 or 20 meters in the air on its 3 kg nylon fishing line. However, it was still not stable enough in the stronger gusts. Numerous re-launches from the grass was the result, with about 40 meters of line out.
To cap it all off, 2 year old Aren retrieved the kite at one stage, and managed to detach the sail from one spar! No more flying for today.
Now, let's go over those 2 problems again, they're easily fixed...
1. Prussik knots are usually fine, but it's probably a good idea to pull plenty of line through so there's no chance of the knot actually getting itself partly un-tied. Teaching myself a lesson here, too! If it just happens to loosen up a bit due to handling, it's an easy matter to grab the 2 pieces that are supposed to lie next to each other and pull them both at once to tighten the knot. You can't over-tighten, it will still slip along the bridle if forced, as it is supposed to. In the air, there's no sideways force on the knot so it holds its position.
2. After getting home I double-checked the position of the towing point and discovered it was still too far back. No wonder the kite had such a narrow wind range! Also, the spars came from a heavy batch of bamboo, unfortunately. It seems this can make a big difference on a small kite. Correcting the towing point and adding even more tail should help this kite to fly stable and high in a moderate breeze.
We'll soon be out again and hope to report on the little diamond flying a lot better, on 50 meters of monofilament fishing line!
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