Soft Kite Posts—Parafoil

It's an archive of sorts, although there are no dates and times. Kite flying is timeless, don't you agree?

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 :-)

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MBK Parafoil Kite

Parafoil Tailless Torture Test

The weather site said 14 kph gusting to 20, but I measured 22 kph at shoulder level while flying today.

A revised Paper Sled had a few brief hops to start with, before I concluded that it needed even more tail and possibly a general scale up in size as well.

Parafoil 3—First Flights

The object today was simply to get photos and some videos for good measure.

Pausing on the concrete steps halfway down to the sand, the breeze was measured with the wind meter. The spinning cups indicated 15 kph and gusts to 19 kph. That was close to perfect for this kite, although the wind strength would measure slightly lower down on the beach.

With its drogue already attached, the new MBK Parafoil popped effortlessly into the air straight after the flying line went on. A couple of guys walking along the beach had seen me attaching the line and at first thought I was doing a spot of fishing!

Plenty of photos were taken, from various angles, as the kite flew on only several meters of line. The smooth southwesterly was making the job easy. Picking up my bag and the winder while the kite continued to float, it was also easy to find another spot to fly. I went down the beach a bit, where the background had some interesting features.

A video was taken while the parafoil soared around on a somewhat longer line. Then it was time to pack up and shift to another location altogether. Inland.

At the reserve, a line of massive cumulus clouds rose past a line of trees at the far boundary. With the kite on a short line I was able to take photos from some higher ground to get a more picturesque perspective.

Finally, with arbout 60 meters (200 feet) of line out, another movie was taken. Arriving home, an online check revealed that the air near that location had been moving at 18 kph and gusting to 22 kph. However, it seemed like there was some lively thermal activity going on as well. Hence the parafoil might have been hit with significantly stronger gusts from time to time. I'm glad the packing tape held, since the line sometimes went very tight with the kite up over 100 feet!

Parafoil—More Fresh Wind Flying

Down at a beach yesterday, the breeze was cold and fresh. It was also much smoother than the previous outing where it was only gusting into the fresh range.

To begin with, the MBK Parafoil was unpacked. As usual, a small drogue was attached to the center of the trailing edge. After some trouble with the kite flapping about in the rough air downwind of my body, I finally got the kite away cleanly. I forgot to check the line tension this time, but perhaps it was a little more than the usual 1.5 kg. In any case, that was no problem for the 20-pound Dacron line and small sand anchor to hold.

After this, the smaller Soft Sled was tried. I say "tried" since it didn't cope at all with air moving at over 30 kph for even 10 seconds at a time. The ram-air spars just gave up, time and again, allowing the front end of the kite to fold right up. It was surprising, since this little kite has done well in quite windy inland weather, right up to 300 feet or so. This just goes to show how much energy there is in smooth fast-moving air!

Meanwhile, the parafoil had been flying smoothly at roughly 45 degrees of line angle. For almost an hour it hovered there, before finally something went wrong...

Was it the bridle attachments again? No, as it turned out. This time a taped seam along one side had given way. Round and round the kite went before lodging into a prickly bush, causing a small slit in one keel.

This incident prompted a design change—to make more use of wide packing tape over those side seams!

More Bridle Mods, New Keels

I'm back from the drawing board, or rather, from online image searches for various flat parafoils!

The keels of the MBK Parafoil are looking like Frankenstein's monster right now, with non-matching plastic and multiple join-lines, but...

I've just been out for a very successful test of the latest keel/bridle configuration for the parafoil. Despite only occasional puffs of breeze sufficient to launch the kite, it flew stable without any tail and to a very respectable angle on about 60 m (200 ft.) of line.

The kite still needs to be checked out in fresh winds though. There's a chance it may not cope with 40+ kph winds on the same bridle settings used today, but we'll see.

Bridle Mods, Moderate Breeze

This will be a short one, like the outing just minutes ago.

Experimentation is progressing on new keels and bridling to get the MBK Parafoil flying smoother. The side keels are now much deeper, with bridle attachment points much further aft than on the original three-leg bridle design. However, it's now a six-leg design with the extra three right on the leading edge of the lower sail-surface.

After a couple of adjustments today, the parafoil and its thin Tyvek tail flew very smoothly in moderate winds. However, the leading edges of the side keels balloon out excessively and occasionally one side flops inward, putting the kite into a turn. It's clear the bridle lines need to be much longer, as is helpful for sled kites. I'll try shifting the forward bridle attachment back down the keels a bit too, to keep those leading edges under control.

It's back to the drawing board!

Parafoil 3—Foiled at 300 Feet

How was it foiled? It was just a bridle-leg attachment point which came adrift, while under some serious strain in a cool fresh northerly. However, the design is sound. I had just taken a shortcut in reattaching the bridle lines after the last round of keel adjustments. It served me right :-)

Before leaving home, the online weather was consulted to confirm whether it was a good day to exercise the final parafoil design in fresh wind. It was a good day indeed, sunshine and all!

On arriving at the field, the kite was soon in the air, trailing the usual small orange drogue. Some video was taken while the kite demonstrated its ability to recover in very rough air, on a short line. There were fresh gusts blowing through and over leafy trees upwind, you see.

With the camera threatening to lose power, I let out the line to 30 meters (100 feet) and took some more footage. This time it was from one side and from more underneath the kite. It was gratifying to see the parafoil reasonably steady and smooth as the wind strength crept up and up. The drogue was working hard though.

It was time for more altitude—400 feet or bust! Well, bust it was actually, just short of 300 feet off the grass. As already mentioned, a bridle line attachment point let go. The kite, flapping an injured wing, limped around in circles until it gently contacted the ground.

There won't be any shortcuts next time.

Parafoil Parrys With Punishing Puffs

Punishing Winds, more accurately—but Puffs had a P in it ;-) In plain English, I went out a few days ago and flew the new MBK Parafoil in rough winds which were gusting over 40 kph at times. Talk about a torture test for a homemade plastic parafoil! Anyway, it coped.

On arrival at the field, the first challenge was to unfurl the drogue without letting the kite blow away. A few moments later I just launched the kite and let the drogue line unwind by itself. So, the double-blue parafoil was soon floating around close to the ground while I took a short movie.

This prototype has much less rake-forward of the air inlets. Also, it employs copious use of wide packing tape along all the seams near the leading edges. Consequently, the kite would pop open easily and hold its shape without collapsing at the first small jerk on the flying line.

Toward the middle of the field, someone else was flying a small retail delta conyne. Being partly cellular, the kite was doing well in the trying conditions. Even so, the kite took on an ominous lean to the right from time to time.

As soon as 30 m (100 ft.) of line was out, my parafoil started catching the brunt of the squally winds. At this time there was still plenty of sunshine although darker clouds were approaching quickly. The side keels fluttered in complaint with every gust over 35 kph or so. But the kite held up. Nothing folded or came apart. Mind you, the normally sedate kite took to darting and surging here and there in response to the wild air.

Finally, it happened; a brief fold-up occurred but was followed with a reinflation a moment later. As the wind strength built even further, this happened more often until finally the kite ended up on the grass. It had found its limits!

Parafoil 2 Pushed Hard

This time, a few strips of wide packing tape were strategically placed to stiffen up various sections of the kite. Down at Knox Park, the breeze was gusting right up into the strong region, so it would be a good test!

In the higher breeze strengths, it was certainly easier to inflate the parafoil. With sail and drogue both in the air, the more generous side keels seemed to keep the kite steadier. At times, on a short line, the kite made some rather good line angles too, considering it was dragging a slightly over-size drogue.

So was the design ready for publication? It was so close really, but no. Time and again, the front end would crease up under a sudden pressure increase, either on one side or across the top. This made it look like a kid with their face up against a glass window. Either scenario would bring the kite down. When creased across the top, the parafoil would sometimes flip on its back and continue to fly for quite a while. Albeit, at a very low line-angle!

Launching in a less-than-smooth manner would sometimes fold up the entire front end of the kite.

It seems the rake-forward of the air inlets is too extreme. Air pressure catches the edge and overcomes the stiffness of the inflated cell(s) when the gusts are strong enough.

Also, using sticky tape along the seams has been OK in gentle winds, but today was a lot windier. The next prototype will have packing tape throughout, which will stiffen up the overall structure when inflated. It worked for the MBK Soft Sled!

The MBK Parafoil will be going to a third prototype, but the resulting design should prove easier to launch and less frustrating to fly than the current one. I'm aiming for a kite which copes with gentle, moderate, and fresh winds with little fuss.

Parafoil 2 Goes Higher

It went higher than it did last time anyway! Winds down at Christies Beach were ideal for giving the new parafoil a good test. Disappointingly, it still required a drogue, but I'll be trying larger keels later to see if that can be fixed—without shifting the towing point, which now seems pretty close to perfect.

The line tension was much lower than for the first prototype. This should be an advantage, allowing the kite to fly higher in fresh wind.

Even with the smooth winds, launching the kite with no helper proved tricky. It seems the best approach is to hold it by the upper surfaces of the inlets, work hands around to where the bridle lines are attached then carefully fly it on the side bridle lines. By slowly slipping the lines out, the central bridle line eventually comes up tight, whereupon flying line can be let out—slowly and with no sudden stops!

The plastic on this kite is so light that a few extra strips of sticky tape will be necessary to reduce the problem of creasing near the front of the side inlets.

The exciting thing about this design is that, by scaling up, anyone will be able to make quite a large parafoil that "looks like a bought one" from a distance, but costs maybe 10 or 15 dollars rather than 100s or even 1000s of dollars.

Parafoil 2 Has Promise

Rain has been in the way for the last few days. But today, between showers, the newly completed second prototype of the MBK Parafoil took to the air. The breeze was rather too light though. Anticipating this, the little 2-Skewer Roller had been taken along as the backup kite.

After a few unsuccessful launch attempts with the parafoil, the roller floated up on about 30 m (100 ft.) of 20-pound Dacron. But even the roller ended up back on the wet grass from time to time.

Every now and again, a gust in the region of 10 or 12 kph would come through, announced by a small stirring of tree leaves upwind. It was fairly straightforward to hold the nose end of the kite up, to let it fill with air.

As is the case with most parafoils in light air, any sudden jerk on the line would tend to deflate the sail. Sometimes this would be just enough to lock the kite into a death spiral to the ground! Other times, a lull would result in the kite going literally belly-up before floating slowly back to earth.

Eventually the line was let out to around 20 m (60 ft.) but line angles were nothing to write home about. At least the kite was stable, right on the bottom edge of its wind range. It needs more breeze and probably some tail. But indications are that this version will do quite a bit better than the first one. Even if it doesn't meet my "no tail necessary" objective, this kite will certainly need less than the first prototype did.

We'll see what the weather brings in the next few days.

Breeze Failed but Rainbow Amazing!

After waiting under a bus shelter during a drawn-out rain shower and getting images of the primary and secondary rainbows left in its wake, I pulled out the MBK Parafoil for more tests.

Initially, the breeze had been gusting over 20 kph. This would have been ideal for checking out the latest kite in somewhat stronger wind than it has experienced so far.

However, when the rain stopped, so did the wind! The air was not completely dead, but it was doing its usual trick of slowly dying away as the late afternoon sun approached the horizon.

All was not lost. In the occasional puffs that came through, I managed to get the parafoil inflated and up on short line lengths. This was enough to get all the bridle legs adjusted after my latest fiddle—an alteration to the forward central keel, bringing the central bridle legs closer together. This was to try and prevent a crease appearing across the middle of the kite when fully pressured up.

At least the kite is now ready to go straight up for a good test, the next time moderate or fresh winds are available.

Parafoil Prototype 1 a Bit Iffy

That last word in the title won't impress the spellchecker, but never mind. This kite has already been out a couple of times, with no real success until today. Initially, the parafoil had cylindrical tubes for cells, closed at the rear end of course to make it a genuine parafoil. This, plus the towing points too far back, made the kite so draggy that it wouldn't climb at all, even in fresh gusts!

Back home again, I took out a long pie-slice from each side wall except the central one. This produced a crude airfoil shape with the upper surface sloping down toward the trailing edge. In flight, the kite now looked much more "like a bought one" and even gained a bit of height with a small drogue attached. A much windier day was needed though.

Today was that day, and the only further mod was a halving of the length of the drogue tether, to make the kite react quicker. That tail end was very keen to flick around at times.

Gusts into the high 20s in kph enabled the dodgy parafoil to get above the treetops for the first time. Flying on 100-pound line didn't help, but the winder was a bit smaller than my 50-pound one and hence was more convenient for the short walk to the local park.

I believe "lighter and longer" will make the next build a much more viable kite than this first prototype. Taking the "pie slice" out of the central cell wall will help, as well.

 

 

 

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