Kite Flying Log

Early 1-Skewer Sled

While May gave Aren rides on the playground equipment behind me, a gentle gust got the sled airborne. Out went a few meters of cotton test-line. So far, so good! It does fly. Seeing it flying, my wife swapped child-minding duties with me and let out a few meters of cotton line herself.

Conditions were very light, and I think the kite was only getting airborne on thermals passing through the park. Having proven its basic flying ability on the test line, I switched to monofilament and had a few more short flights. After maybe 20 minutes or so there came a period of slightly stronger wind. That was more like it.

Out went maybe 20 or 30 meters (100 feet) of nylon line and the little homemade sled ventured right up near the tall treetops, filled with the air that was blowing the leaves around just a few meters behind it. It rocked a little side to side and tugged more strongly on the line than the diamond would with the same wind speed. After about 4 minutes, the wind died and the sled ended up on the grass again. It was time to pack up.

See if you can spot the sled and its two tails, trying to disguise itself as a cloud, in the photo.

MBK 1-Skewer Sled number 1 was flying at about 30 degrees to the horizontal, which is reasonable for a sled kite. However, I hope it will settle out at around 40 to 45 degrees with a bit more wind. Perhaps even 50 or 55 degrees might be possible with a bit of thermal help one day. That's for some other day, but for now we are happy that the kite is proven! The only thing we noticed was that it hangs left slightly, so I will be putting a strip of tape on the right hand spar to balance it better, when we get home.

This kite is almost invisible in the air! It needs brightly colored tails I think. Maybe we'll make up a couple of tails from a red or green-plastic shopping bag—not as light as freezer-bag plastic, but still reasonable.

Let's play "drop the reel"

We tried the latest delta first, on the 17-meter (55-foot) cotton test line. It seemed stable at first, but after moving to one side too far it would gracefully do a half roll and then dive to the ground. Ooops. It was always to the left too, so I added some extra clear tape to the right spar about halfway along to improve the balance. This, plus a couple of paper clips near the tail end improved its behavior to the point it got up 10 meters (33 feet) or so, but then the same problem occurred. Sometimes it was to the right, so at least the left/right balance is right. I'm sure even more weight to the tail will result in a decent flying kite. No wonder flat deltas never got popular! The balance and attachment point have to be just right for them to fly at all.

So it was back to the trusty little diamond. By this time, the wind had picked up just a little. After a few short flights we had the diamond dancing around in the air with more than 50 meters (160 feet) of monofilament line let out.

There's Aren (17 months) in the photo, flying the kite with his right hand. He's just dropped the reel with his left hand. It's in midair, just about to hit the grass! The monofilament line is barely visible, leaving his hand at about a 40-degree angle in the photo. Typical of kite flyers in his age group, he's more interested in the reel than the flying kite!

It was a nice feeling, seeing a kite climb away slowly in light conditions with line spinning off the reel. This was a height record, so I will be describing the flight more on the "Kite Altitude Record" page! Much more line could have been let out but at the risk of a tree landing if the wind died suddenly! So we played safe.

Date: Sun Jul 15, 2007
Location: Old Reynella (vacant block)
Weather: Very light breeze, variable, cool
Kite(s): MBK 1-Skewer Diamond prototype 1

Comments: It was a similar experience to yesterday, and I didn't bother with the cotton line at all. It's made me think that in very marginal conditions, laying out a lot of line and towing the kite up might work—just for those occasions where you know the kite only needs that extra knot or two of average wind-strength to stay in the air!

You'll often see in print that there's no point in running along towing a kite. But if you are flying a very light wind kite outdoors, this is not necessarily true! Wind speed close to the ground always increases with altitude, up to a point. That's because it gets slowed down by stuff on the ground like grass, fences, houses, and trees. Sometimes a kite will only stay up when it's well clear of everything on the ground.

Under some conditions, in higher winds, the wind speed can keep getting stronger for hundreds of feet up. That's called wind shear or wind gradient. As a glider pilot many years ago, I can remember sometimes flying through wind gradient on approach to a landing. But hey, this is supposed to be a kite site, so enough of that ;-)

Date: Sat Jul 14, 2007
Location: Old Reynella (reserve)
Weather: Very light breeze, variable, cool
Kite(s): MBK 1-Skewer Diamond prototype 1

Comments: All three of us went out to the reserve, hoping for the best despite the nearly calm conditions. I got a few meters of cotton line out but only managed to get the kite to hang briefly in the air before it settled back down to earth. Right, now it was time to attach some really light line and see what happens.

With the 3 kg monofilament attached, things were more promising. After a few short flights, I decided to tow the kite up higher to catch some of the gentle gusts that were passing through. With the kite and its tail carefully laid on the ground about 15 meters (50 feet) away, a firm pull popped the diamond into the air, and after jogging for a few meters it was at treetop height. It's not a bad little light-wind kite this one, despite its small size! Freezer-bag plastic and bamboo skewers are a good combination.

Having waited until there was some movement of leaves in the tops of the trees, the little diamond hung in near treetop level for a minute or two. It gently wobbled from side to side as its long tail streamed out behind. This was quite impressive since I really didn't expect much success on this outing. Even at the height of the tall tress surrounding the reserve, there just wasn't enough wind speed to keep the kite up. At least we saw it fly and with no tendency to hang left. The added weight of two extra bits of tape on the right tip did the trick.

Date: Fri Jul 13, 2007
Location: Old Reynella (vacant block)
Weather: Light/moderate breeze, some gusts, cold
Kite(s): MBK 1-Skewer Diamond prototype 1

Comments: I thought I would throw together a little diamond kite while working on delta number 3. We took it out today for its first test fly. It went straight up in the cold breeze, but turned out to have a tendency to go left. Sometimes it went right to the edge of its flying window. Despite this, it often corrected itself long enough to climb high on the line. A little bit of looping occurred during strong gusts, but that's to be expected.

It's hard to be super accurate when making something on a small scale! I took care to balance the frame, so maybe the lop-sided flying is due to there being a bit more sail on one side than the other. Anyway, we'll see what a bit of extra weight on one side will do, next time we go out. On a kite this small and light, that just means sticking on a few short strips of tape in the right spot.

Aren had fun, flying the kite from his pram. He held the reel for a half minute or so, with most of the line let out. He seemed more interested in the reel and the cotton line nearest him than the flying kite! Predictably, he eventually let go, but the reel dragged through the grass at about walking pace. It was no problem to catch it.

The line used was from the Baby Sled. It's down to around 17 meters (55 feet) now since I've been pinching some to use for bridles! A neat little clip made from a paper clip lets me attach the line to any of my kites now. This short cotton line will be useful for testing; we'll use the nylon monofilament later on to get some real height.

Up to now, the standard way of adjusting a bridle was to tie a knot in it. This way, the attachment point can be shifted forward or back a bit. This is not very neat nor very precise. So, I've invented the MBK Multi-attachment Bridle ;-) Basically, it's just a bridle with a series of small loops tied into it. Now, adjusting the bridle is just a matter of clipping the line into whichever loop works best on the day!

Date: Tue Jul 3, 2007
Location: Old Reynella (reserve)
Weather: Light/moderate breeze, gusty, cool
Kite(s): MBK 1-Skewer Delta prototype 2

Comments: The breeze was up and the sun out, so it was off to the reserve with the usual pram / toddler / kite combination. Once there, it turned out to be a frustrating experience. To sum it all up, I eventually got the kite trimmed to fly reasonably, but it seems the more swept-back design is very tricky as a flat kite. Even with generous amounts of tail, it spent a lot of time on its side, at all altitudes. It was fairly sensitive to the bridle attachment point position, but the paper clips at the bottom made less difference. Interestingly though, it never looped in strong gusts, so my careful attention to accuracy and balance during construction did have some effect!

Come to think of it, most successful flat kite designs have more sail area at the top than the bottom. Most obvious example would be the classic diamond kite, or arch-top kite. Even equal area, as in rectangular Japanese kites, works fine. Being a small kite, I don't want to add weight or complexity with a keel, so the next step is to go back the other way. That is, make prototype 3 even less swept-back than prototype 1! On top of that, I'll refine my construction method even more to get the frame perfectly aligned and balanced, and we'll see what happens. When I get it perfect, I'll publish detailed step-by-step instructions, with photos, on this website. That way, you can share in my success if you want to!