First KAP Session with an R/C Rig

The first weekend after finishing the build of my R/C KAP rig, the wind was good enough to test it out. I decided to go to St. Mary’s College, which I’d KAPed one time before, but I hadn’t gotten pictures from quite the best angles. The new rig would allow me to see what the camera is pointing at, so I could be sure to get the desired composition. Plus, the wind was out of the west, which is ideal for this site.

The wind was gusty and near the upper limit of what my kites can handle: 15 mph with gusts to about 20. I had flown the Mini Dopero in wind like this several times before, though, so I knew it would be up to the task. The good thing about flying in a stronger wind is that it takes no effort to get the kite in the air, and this time was no exception. Apparently, I last flew this kite in similar winds, because it required no trimming once in the air, and the pull seemed reasonable for the wind speed (i.e., plenty but not too much).

Besides the rig, I was also experimenting with another new piece of equipment: a dog stake to hold the line while I set up and take down the rig. This stake replaced my big-ol’-bag-o’-rocks. It turns out it is much easier and more convenient than the bag. I think I will use it from now on any time there is suitable ground to put it in. Thanks to Kidafi Byer on the KAP Facebook page for the suggestion!

The winder wrapped around a dog stake a few times, with the KAP rig almost ready to be attached

I let the kite fly by itself with the winder attached to the stake for a few minutes to make sure it was stable. Then I attached the rig by wrapping the line about four times around each of the Brooxes Hangups at the ends of the picavet suspension, separated from each other by a few feet on the line. I plugged in the battery for the rig, turned on the PowerShot S100, grabbed the winder, and away it went! Here are a couple pictures of the rig attached to the line.

Another good thing about flying in a stronger wind is that the kite has no problem lifting the rig. This rig does weigh about 4 oz / 115 g more than my fixed one, which I imagine will make a difference on those days with barely enough wind to fly, but today the kite could have certainly lifted a lot more if it had to.

Since this was my first time flying an R/C rig, the process was a bit new to me too. When I wanted to take some pictures, here is what I had to do:

  • Turn on the transmitter. I leave it off when not taking pictures because that seems to put the receiver in a sort of standby mode, with the servos completely still and, I assume, consuming minimum power.
  • Turn on the FPV monitor.
  • Switch on the video downlink, which is controlled by the flaps switch. (The VTx is also left off when not in use to save the battery.)
  • Pan and tilt until the rig is facing approximately the desired direction, and then flip the switch to take a bunch of pictures. Hopefully some of them turn out well!
  • Turn off the VTx and the transmitter again and fly the kite some more!

The way the sticks and switches are arranged on my transmitter, and because it is attached around my neck with a strap, I can operate the rig completely with my left hand while holding onto the kite reel with my right hand. If the kite suddenly needs attention, the transmitter can be pushed aside so that I can focus on just flying the kite again.

Video downlink from the KAP rig

Above is a video showing what the video downlink looks like. It was a gusty day, and that definitely shows up in the video! (Remember, this video is not high quality nor stabilized, as the stills from the main camera are the “end product.” Its purpose is just to show me where the rig is pointed and what the general composition of the photo will be.) With all the bouncing around, taking pictures is definitely a somewhat approximate endeavor. For that reason, I leave the camera in continuous shooting mode and leave the switch down to take a bunch of pictures once the rig is pointing in the right direction. On less gusty days, I imagine things will be a lot smoother!

Despite all the gusts, I did manage to capture pretty much all the pictures I wanted from this session. The money shot is up above, and also at the end of the gallery below. I really like how that one turned out. The composition is just about perfect, with most of the school visible in the foreground, St. Mary’s River prominent in the background (with some sailboat racing going on), and a beautiful big blue sky. Also of note is the baseball field — which I didn’t even know existed until I saw it from the air — with a game in progress. There were several other good pictures too, taken from a variety of angles and heights. The straight-down image of the soccer field is something I never could do before!

The first time out with the R/C rig was definitely a smashing success. I’m sure I will still use the fixed rig sometimes, maybe on days with very light wind, but being able to see and control the camera is really fun and rewarding. Even though the video feed may be shaky, it still gave the results I was hoping for.

The one big mistake I made was accidentally stepping on my transmitter after I was done taking pictures and had put it on the ground. Woops! 😕 That happened due to a sudden lull in the wind, to which I responded by backing up quickly to keep the rig from falling to the ground. Then I heard that gut-wrenching CRACK! Thankfully, the only damage was a broken monitor mount, which can be fixed with some sanding and glue.

Here are some things I learned from this first session with the new rig:

  • The low power setting (25 mW) on the VTx seems to be plenty. I didn’t experience any problems with reception.
  • The 500 mah battery for the rig ended up about halfway expended after what I consider a pretty typical flight, so the capacity is fine. That would not have been the case if I didn’t have a way to turn on and off the VTx from the ground, so that is a very valuable feature. (The alternative is a much bigger and heavier battery.)
  • I will take more pictures next time. I came back with only 31, which resulted in plenty of “keepers,” but it wouldn’t have hurt to have more to choose from. Part of the reason for the small number is that the S100 is pretty slow in continuous shooting mode, especially when saving RAW images. Next time I’ll just hold down the shutter for longer each time. Still, it was nice only having to sift through 31 images instead of the 400 that I normally get with the fixed rig!
  • When putting down the transmitter, make sure it is far away from where you might step. I was lucky to get away with no damage to the electronics.

Well, this has been fun. I’m sure I will have many more adventures with this R/C rig in the future!

Flying in a Cloud

We had just gotten our second significant snowfall of the year. I was eager to do some KAP, since we don’t get that much snow here in Southern Maryland, and I’d never flown a kite or taken aerial photos in snow before. I missed the ideal time, which would have been during the afternoon of Friday, Feb. 12, but the forecast looked good for wind on Sunday morning.

I packed up my gear and headed over to Chancellor’s Run Park, which is nearby my house and is known to have nice views of Lexington Park and California, MD when looking to the north. The cover photo on the home page of this website is one such example. I thought it would be nice to see what that landscape looks like when covered in snow. Since I’ve done KAP from this park several times before, I decided to switch it up a little bit and fly from a soccer field on the northwest side of the park, rather than the central baseball fields that I normally choose.

By this time, the temperature was well above freezing, and the ice and snow were melting. The ground was quite wet and soggy, and water was dripping from the stadium lights overhead. There was snow remaining on the ground, though, so there was still hope of capturing some nice frozen landscapes. The wind at ground level was light, so I set up the big Barn Door kite and did a running launch. It took a couple attempts and bridle adjustments, but eventually I got it flying and trimmed out well.

Here are a couple low-altitude shots near the launch site. It is pretty obvious from the second photo just 100 or 200 feet up that the visibility was going to be poor. From the ground, I could tell that there were low clouds, but I didn’t know how low. I would soon find out. 🙂

To add some more variety, I took a walk with the kite along the parking lot towards the building with a flag in front of it that can be seen in the second photo above. I let out more line as I went and carefully maneuvered the kite line over the stadium lights and trees. Once the kite reached approximately 400 feet above the ground, it started disappearing in the clouds! This was a new experience for me, and kind of fun! It is weird to have a kite line in my hand going up into the sky with nothing visible attached to the end of it, as if I were doing some sort of sky fishing.

Normally, flying a kite in the clouds is probably not a great idea, but considering how low they were and the really poor visibility, there was no chance of an aircraft flying by and hitting it. There was also no one else in the entire park — not surprisingly, given the weather — so if something happened to the kite while in the cloud and it ended up crashing, there wouldn’t be any injuries or property damage. Here are a couple images of the kite disappearing and reappearing in the clouds. I would have liked to get one just showing the line and KAP rig below the clouds, but it was pretty much impossible to get the camera to pick that up and focus on it.

The Barn Door kite disappearing and reappearing in the clouds

Obviously, with the lack of visibility, I wasn’t able to capture the snowy landscape how I wanted, but this was still fun and a bit different. The best pictures from the session were probably the lower altitude ones, like the one showing the baseball field below. The cover photo for this post is also reproduced as the second picture in the gallery below. I like this one because it is relatively clear but still gives an idea of how cloudy the conditions were that day. The third one shows the camera’s perspective when it was almost fully engulfed in the cloud. The kite, attached 200 feet beyond the camera, was certainly invisible at this point!

As I write this post, it is now March, and things are starting to warm up again, so it’s unlikely I’ll get a chance to capture the snowy landscape I was hoping for. Maybe next year!

Governor Thomas Johnson Bridge

The Governor Thomas Johnson Bridge is one of the most recognizable landmarks of Southern Maryland. It crosses the Patuxent River, joining St. Mary’s County and Calvert County, the two southernmost counties in Southern Maryland. It also is fairly long and tall, making it visible from fairly long distances; as such, it has already appeared in a few of my aerial photo shoots from other locations. You can find it on the main cover page for this site, for example.

Some Google sleuthing revealed that there is a large empty field next to the bridge, which, as far as I can tell, is not private property. There is even a kite fly-in that normally occurs there every year, so it has to be a good place to fly kites. Here is what the flying site looked like from the road when I arrived:

Large empty field adjacent to the bridge

It was a bit of a walk from the road to the edge of the water where I wanted to fly, but it wasn’t too bad. The wind was kind of in-between the range of my two kites. It seemed like it might be somewhat of a struggle to get the Mini Dopero off the ground, but at treetop level it was blowing pretty steadily. I decided to fly the bigger Barn Door kite despite the fact that it might pull pretty hard at times, because I knew it would be easy to get in the air in this wind.

That estimation was correct. Soon after setting up the kite, it was flying steadily on 100 feet of line. The wind was blowing from the north, so flying on the south side of the bridge meant that there was no danger of the kite going over the bridge. I wouldn’t have minded an east wind to get the kite over the water and closer to the bridge, but this should do fine anyway. The kite was tending to pull to the right when the wind got stronger, so I brought it down and made a quick adjustment to the bridle. It turns out that I overdid it, because after that the kite wanted to pull to the left. That would be okay, though, because it meant that if the kite did get pulled down by a stronger wind, it would be safely over the spacious empty field. After launching the kite again, I attached my PowerShot S100 fixed autoKAP rig, started the CHDK script to take a picture every five seconds for a little over 30 minutes total, and sent it up.

PowerShot S100 fixed-angle autoKAP rig hanging from the kite line

I had a bit of a conundrum about how to aim the rig this time. The rig can be rotated in increments of 45 degrees. My desired framing is basically what you see at the top of the page: I wanted to get most of the bridge in the frame, including the end on the other side of the river. The wind was coming from the north, perpendicular to the bridge, so I ended up aiming the rig 45 degrees to my right (west) to hopefully get the bridge in most or all of the shots, and at least some with the desired composition. That ended up working out pretty well, though most of the images didn’t get the end of the bridge in the frame like I wanted. This is one of those cases where it would have been nice to have a radio controlled rig, but the fixed autoKAP rig still gets the job done in the end. Here are the pictures I like from the session, from a variety of different heights and angles (the second one is the cover photo above).

Flying was a bit of a challenge given the wind and how the kite was set up. Well, not really a challenge, but not as smooth as I would have liked. The kite was pulling pretty hard for much of the flight, and when that happens, this kite tends to go down to a low angle. It was also pulling to the left a lot due to my misadjustment of the bridle. That wasn’t all bad, though, because it resulted in some nice low altitude shots with the field and trees in the foreground, like the third one in the gallery above, which I probably wouldn’t have gotten otherwise. At times when the wind let up a bit, it managed to reach much higher angles and heights, like in the cover photo.

After awhile, I brought the camera and kite back down. While doing that, some other visitors joined my airspace, including a bald eagle and a drone, and, right as I was leaving, a whole flock of geese. This was a good outing, as it always is when the kite and camera return in one piece and you get some good pictures! I will definitely return here again, probably when there is an east wind and some green on the ground and trees. I’d also like to take some pictures of the rest of Solomon’s Island, which is to the south of where I flew this time. I’m not sure if there is another suitable flying field, but getting the kite nice and high from this site and taking pictures in that direction should work.

You can find my gallery of all images from this location here. For now, it only contains the pictures you’ve seen here, but I’m sure there will be more eventually.

Thanks for reading! If you enjoyed it and would like to read more KAP stories, feel free to subscribe to SOMD KAP by entering your email in the box on the main page.

KAP at Home

Ever since I started doing KAP last year, I’ve wanted to see what my neighborhood looks like from the air. Actually, I had a good idea already, since I’ve been flying my FPV (first-person view) radio-controlled airplane from an open area at the end of my road. But the camera only does low-resolution analog video, which is not well suited to making out details, and especially not distant objects. It’s also very wide-angle, which gives a somewhat distorted view of the world. I wanted to see what the neighborhood really looks like from above, not a low-resolution, distorted approximation!

Some sample pictures from the FPV camera on the plane are presented in the gallery below. The first one shows the flying site on the bottom right. The second one shows the type of view I hope to get from the kite, except, of course, higher quality and with a level horizon. The flight video is below that too, just in case you are interested. 🙂

Snapshots from FPV camera onboard a radio-controlled plane

Alright, that’s enough about R/C airplanes. Back to kites…

The area where I fly the plane is probably the largest open area in the neighborhood that has sufficient room to fly a kite without it going over houses. I wouldn’t want to creep people out by flying a kite with a camera over their house, and I especially wouldn’t want the kite or camera to crash into a house or end up with the line strung across someone’s property or the street. There are two problems with flying from that area, though: it is lower in elevation than the surrounding land (it is actually a drainage area), and it is mostly surrounded by large trees. Both make it difficult to fly a kite there.

I realized, though, that my chances successful kite flying are significantly improved during the winter. Since the trees have lost their leaves, wind is able to pass through much more easily than during the summer. If the breeze is in the right direction, it can result in wind near ground level that is steady enough to launch a kite and get it above the trees.

Well, a day came along with conditions that seemed workable. The wind was from the north, which meant it was relatively unobstructed by hills and also would allow the kite line to extend over the length of the drainage area. That gives the largest possible safety box and also keeps the kite away from houses. It was relatively strong and gusty, up to about 20 mph, but by this time I’d flown the Mini Dopero in similar winds and knew it was up to the task.

I set up the kite and did a long line launch. The first attempt resulted in the kite floating back to earth during a lull in the wind, but the second attempt was successful. Following my experience the last time I flew this kite at Elm’s Beach Park where it was pulling very hard, I had adjusted the tow point on the bridle forward by a couple centimeters. That seemed to be just about right, since the pull was much more manageable. I was also flying with a new, more colorful drogue (made out of spare blue and yellow ripstop nylon), since the last one had been lost in the Chesapeake Bay. About 150 feet of line were needed to get the kite safely above the turbulence produced by the trees. The next step was to attach the PowerShot S100 rig to the line and start the intervalometer, which happened without a hitch.

The flight really went about as well as I could have hoped for, given the conditions and location. Once again, the Mini Dopero handled the strong, gusty winds like a champ. Gusts and variable wind direction caused it to fly off to one side or another from time to time, but there were no near crashes or real scary moments. Nonetheless, I didn’t release all the line available, just because I didn’t want to push my luck.

The gusty behavior resulted in images captured over just about 180 degrees of view with the fixed rig, which I see as a benefit. Some of the best shots are shown above. The quality is definitely much better than the FPV camera, of course, and they show off some of the prominent features of the area. The most noticeable feature is the big white tower off to the east. Interestingly, I never even noticed this tower until I first started flying my R/C planes around with cameras attached. It’s very prominent from the air but somewhat obscured from the ground. That’s just one example aerial views really give a different and unique perspective. Farther to the east, the control tower for the Patuxent River Naval Air Station is visible miles away. There is a small pond in the neighborhood in the first image looking towards the north, a larger one in the last image towards the south, and an even larger one beyond the neighborhood farther to the south. I even got one good shot of the flying site from above:

Bringing the kite back down was pretty uneventful too, except for near the ground where the turbulence from the trees caused some “interesting” kite behavior. My timing happened to be just right that the intervalometer script kept going just until I was about to land the kite, giving me some close-up images of trees:

Right after that, the script finished and the camera shut off. I detached the rig from the line and brought the kite down, being careful to keep it away from the hungry trees. Another success! I think I might be getting better at this kite-flying thing. It would be nice to try this again when there are some leaves on the trees, but I don’t know if it will be possible with the wind conditions. Anyway, you can see these and any other KAP pictures I may take from home at the My Neighborhood Aerial Photos Gallery page.

St. Mary’s River State Park

St. Mary’s River State Park is a beautiful area in Southern Maryland whose main feature is St. Mary’s Lake. There is a 7-mile walking trail around the lake, boat docks, places to fish, a playground, etc. I had visited the park several years before when I first moved to Southern Maryland, but now kite aerial photography was giving me a good reason to go back.

I had also gone to the park earlier in the week in hopes of flying but was stymied by a lack of wind (you know, that thing that kites need to fly). Since there was a $3 fee to enter, I didn’t want to let that go totally to waste, so I walked around and took some pictures. Here are a couple of them. Notice the reflections on the glass-smooth water in the second one — a sure sign of very little wind! One very beneficial outcome of that trip was that I located a very good flying site: a wide-open field about 300 feet wide and 700 feet long at the southeast end of the lake. This would be a perfect place to fly a kite.

The next Saturday, the wind was pretty calm most of the day but seemed to pick up suddenly in the early afternoon. After getting the go-ahead from the boss (my wife 🙂 ), I quickly packed up my kite stuff and hurried over to the park again. In my haste, I forgot to bring gloves, which I realized during the drive, but I decided not to go back for them. It turned out that I got lucky and didn’t need them because the wind was quite light, but generally speaking it’s not a good idea to not wear them when flying a big kite.

During the drive, I tried to judge the wind by looking at the tops of the trees, and it wasn’t looking too promising. The gentle-to-moderate wind I had observed at home was no longer apparent at all. When I arrived at the gate, I made the choice to go in, fully knowing I might be wasting my $3. The hike to the field didn’t do much to improve my outlook. Only rarely did I see the tops of some trees moving. It was looking like another disappointing attempt, but at this point I was definitely going to at least try.

If anything was going to fly, it would be the big Barn Door kite. I set it up as quickly as I could at the field, which is still about a ten-minute endeavor. Despite my misgivings, in the open field there was definitely a noticeable light breeze. Surprisingly, it remained steady enough to get the kite into the air with no running needed. I let out the line as quickly as I could while periodically pausing to let the kite pull up to a higher angle, knowing full well that a light breeze can quickly disappear. The best bet is to get the kite well above the treetops as quickly as possible where the wind is generally less likely to suddenly vanish. With the PowerShot S100 pointed towards the north, the rig was soon attached and on its way up. That’s a relief!

The picture above from about a hundred feet up gives a nice view of the flying field, the northeast end of the lake, and some hikers passing by. Since it was a very nice day by winter standards, the park was recently reopened, and it was a weekend, there was plenty of traffic. I got some comments, mainly from kids (as usually is the case), and had some brief socially-distanced discussions about the kite. No doubt the big blue and yellow kite could be seen from quite some distance.

The flight turned out to be just perfect for the Barn Door kite. I don’t think the wind ever got much higher than the light range. That allowed the kite to fly at a high line angle; it didn’t get pulled down at all as it tends to in stronger winds. There wasn’t a lot of pull on the line, but it was still plenty to lift my 300-gram picavet rig. To introduce a little bit of variety into the shots, I walked back and forth along the width of the flying field. Some variability in the wind direction provided views of both ends of the lake, and also some looking down towards me.

Actually, with the wind so light and the camera nominally pointed towards the kite line, many of the shots ended up focusing on the line rather than the landscape. I haven’t really had that problem much before. In the gusty breezes typically encountered, the camera normally moves around enough that the line doesn’t end up directly in the center of the frame too often, even when the camera is nominally pointed towards it. Next time, I may try manually focusing the camera to infinity if the camera is pointed that way. Nonetheless, there were still plenty of good shots out of the 400 taken. Having some focused on the line actually made it easier to narrow down the “keepers.” Some of my favorites are posted below. They really show off the serenity of the lake and the beauty of the surrounding area.

After 30 minutes of flying, the breeze had died down to just about nothing on the ground. The images above are in chronological order, revealing that the lake was taking on an increasingly mirror-like appearance as the wind died down. If you view the last one full-size, you should even be able to make out circular ripples surrounding the boat in the lower-left corner. As is often the case, there was still a breeze at altitude, but I sensed that this too was starting to decrease. Once below 200 feet, the wind definitely dropped off. By the time the rig was down to ground level, the kite had lost all lift, so there was no way to detach the rig from the line with it still flying, and I was left just tugging on the line as the kite descended to make sure it stayed clear of the trees. It looks like my timing was just right, because I definitely wouldn’t have been able to launch again at that point. I packed up and went home with that sense of satisfaction that only a relaxing kite flying session can bring. Not bad for the first one of the new year!

You can see all my aerial photos from St. Mary’s River State Park at this page. Thanks for reading!

Elm’s Beach Park

It was time to take some aerial photos of the Chesapeake Bay! As one of the most prominent geographical features of the area, it definitely needs to be featured on this website. I remembered that Elm’s Beach Park, public beach area, exists because I had gone there a few years prior. It’s located about 6 miles south of the Pax River Naval Air Station, as the crow flies.

Since it was winter, there was no fee to use the beach, but the main parking area was closed, meaning I had to walk more than 0.6 miles from my car to the beach. That’s not so easy with my kites and KAP gear, especially my 30-lb bag of rocks! It was a pretty walk, though. Down below are pictures of the walk and the beach itself.

Long but pretty walk to Elm’s Beach

There was a couple of photographers who followed me from my car all the way to the beach who were probably wondering what the dickens it was that I was carrying. 🙂 Well, they would soon find out. We’ll see them a little later in the story. When I got to the beach, the wind was blowing out to sea. The wind strength was definitely in the Mini Dopero’s range, so I assembled it quickly and attached it to the kite line. I also attached the drogue to keep the kite stable in the stronger wind. Just like the last time I flew near the water, the wind was pretty steady, and getting the kite in the air was no problem even though there was no room for a long-line launch.

With somewhere between 50 and 100 feet of line out, I wrapped the winder securely around the straps of my heavy bag of rocks, attached the PowerShot S100 picavet rig, started the intervalometer, and away it went. Now that a couple hundred feet of line were out, the kite was pulling quite hard. Apparently, I should have moved the tow point forward to reduce the force a little bit, but now with everything set up, the idea of bringing it back in and starting over wasn’t too attractive. I could use a workout anyway. The steady breeze offered no time to relax. A few times I had to just put the winder down and sit on it for a few minutes to give my arms a break.

Fellow photographers walking on the beach below

Throughout the course of the flight, several groups of people walked by, some of them commenting and even striking up short conversations about the kite. (Kids were the most interested, as is usually the case.) The first to pass by were the photographers that followed me from the car. They took their time to get to the beach, so they arrived after the rig was already in the air. They continued down the beach past my location, taking photos as they went. Eventually, they arrived at an outlet from the nearby Biscoe Pond into the bay, which is visible in the picture above. There is no bridge to cross over it, so they turned around. When they passed by again, they said hello and seemed appreciative of the kite, although I don’t know if they noticed the camera attached to the line.

Views looking northward directly along the shore (first picture) and somewhat inland towards a pond (second picture), taken near max altitude for the flight

The camera was pointed north to take pictures along the shore. The first picture in the gallery above has the Naval Air Station in view off in the distance. There is a pattern of sandbars just under the surface that run parallel to the shore and were not visible from the ground. Five or six of them can be seen, and they seem to be fairly evenly spaced, the last one being probably a few hundred feet away from the beach. I don’t know if these are unique, but I thought they were quite beautiful and interesting. The second picture looks a little bit more inland, where a small pond and a house are visible. That is actually the second of two adjacent ponds, the first one being Biscoe Pond, which was right behind me. (Google Maps doesn’t give the second pond a name.) Since the camera wasn’t pointed at it, the only time I got a picture of Biscoe Pond was when a gust swung the kite and camera around. It came out very tilted, but anyway it gives an idea of the size and shape…

Biscoe Pond, directly behind me

After nearly an hour of grueling work letting out the line, it was time for another grueling hour to bring it back in. Despite the strong winds, the kite never seemed to be in much danger of diving or going out of control. It did pull to one side and then the other for extended periods at times, but there were never any close calls. I took the picture on the left on the way down when the rig was within a hundred feet of me. Eventually, the rig was back down on the ground. That’s when I decided to tie down the kite and try to go take some pictures from the side. What could possibly go wrong?

Well, I did get some nice pictures from the side, including the one below. Doperos are definitely nice looking kites when in the air. Unfortunately, I found out doing this that things could go wrong. Down low the wind is gustier, and without much line extended, the kite doesn’t have much space to recover on its own from a dive. And of course, with me not managing the line, I couldn’t intervene either. You’ve probably guessed by now — the kite ended up in the bay. Thankfully, it wasn’t that far, and I was able to pull it back to shore by the line. Also thankfully, the camera was safely on the ground already. The only loss or damage was the drogue, which must have gotten stuck on something in the water, because it was no longer attached once the kite was retrieved. Hopefully it doesn’t end up choking a baby penguin or something like that.

A picture snapped from the side of the Mini Dopero right before it took a dive in the bay

I flew the kite for a few more minutes to help dry it off, and then I packed it up and made the long walk back to the car. It was a successful but tiring KAP session! You can see all my aerial photos of Elm’s Beach Park at the Elm’s Beach Park Aerial Photos page.

First KAP Session with the S100

The Canon PowerShot S100 (and other ones of the same lineage: S90, S95, and S110) is a popular camera for KAP. It’s a bit old now, but it has many advantages:

  • A larger sensor and faster lens than a typical small-sensor compact camera, giving sharper images with good contrast and colors
  • A wide minimum focal length, equivalent to 24 mm on a 35 mm camera
  • It’s fairly small and light, weighing 7 oz with the battery and memory card installed
  • It’s fully supported by CHDK
  • It has a shutter-speed priority mode and can shoot in RAW
  • Can be picked up used for fairly cheap

I decided to gift one to myself, since it was that time of year after all. While I was waiting for Christmas to arrive, I made a new picavet rig designed around this camera. The main goal was to shave off some weight, since the S100 weighs 2 oz more than the PowerShot SD1400IS I was using previously. In the end, the entire rig, including the camera, came in at 10.8 oz, which is only 0.5 oz heavier than the old one. That’s definitely worth it for the image quality upgrade! If you want to read more about my KAP rigs and cameras, browse over to this page.

I also decided to try a new location, George B. Cecil Park. It’s a pretty typical park for this part of the world, with various sports fields and a playground. It’s closer to the west side of the peninsula, so I thought it might be a good idea to see if the Potomac River was visible from the air.

Wind on that day was a little hard to judge. At home, at times it seemed pretty light, and other times stronger and gusty. Better bring the Mini Dopero and the Barn Door kite, just in case. It was also quite cold, around freezing temperature. The wind was still a bit hard to judge when I got to the site. Up in the trees, there seemed to be some decent gusts, but I didn’t feel a lot on the ground. I took the big Barn Door kite to one side of the field on top of a small hill and started the process of setting it up. I immediately noticed more wind at the top of the hill, and soon it became very apparent that it was going to be too much for this kite. At least there was finally some certainty!

So the Barn Door kite was packed up again, taken back to the car, and switched for the Mini Dopero. I brought a drogue too and soon had the kite ready to go. Flying in the gusty winds was challenging, because low to the ground the kite would either not get enough and fall to the earth, or too much and pull off to the side. Obviously, some bridle adjustments were necessary. I was a bit overzealous on moving the tow point forward to cope with the stronger winds at first, which caused it to sometimes pitch forward and lose lift, so I moved it back again somewhat. I also adjusted the upper prusik knot a centimeter or two to the right, since the kite seemed to be pulling left most of the time.

Eventually I got the kite flying stably (or as stably as could be expected in these conditions) and attached the new S100 picavet rig to the line. There was a row of trees looking hungry for a kite to the left of where I launched, so I decided to walk to the right to get a little more breathing room. I first tried the adjacent softball field, then ended up in the empty parking lot. Eventually I returned to the softball field when it came time to land. The progression from launch location to the parking lot was captured by the S100 in the series of images above.

The rest of the flight went pretty well, but I was still nervous about all the wind and the nearby trees, so I didn’t fly any higher than a few hundred feet. I managed a few nice shots, which you can see below. At that height, the Potomac River and even the bordering state of Virginia are visible off in the distance in the last image of the series. I would like to come back here some time when the wind is more agreeable and fly either from either the soccer field or the baseball field on the west side of the park, and get the kite as high as possible to see further. Another option is to point the camera east, where St. Mary’s River should be visible.

This flight definitely increased my confidence in the Mini Dopero in difficult conditions. Properly adjusted and with a drogue, gusts up to about 20 mph are not a problem with this kite. That’s good, because it means that between my two kites, it’s possible to do KAP in about 5-20 mph winds, or about Bft 2-4.

I was impressed with the new camera as well. Despite having slightly lower resolution than my previous camera (12 MP instead of 14), the lens and sensor are better at resolving detail and giving a sharper overall image. Being able to shoot in RAW mode is a big benefit, since exposure, colors, sharpness, shadows and highlights, etc. can all be adjusted afterwards to improve the results. It’s not the ultimate KAP camera by any stretch, but if you’re mostly interested in still photography like me, it would be hard to find a better value.

Kite Simulations

At work, use computational fluid dynamics (CFD) to simulate air flow over aircraft, ships, things carried by aircraft, etc. I also get the chance to do a little bit of development work. This past year, some people have been asking for the capability to simulate catenaries — in other words, cables and systems of cables used to connect objects together in dynamic systems. These are used for all sorts of purposes, including towing objects behind boats, connecting a parachute to a jumper, lifting objects with helicopters, and (the thing that gets me excited) flying kites!

I always jump at the chance to do anything related to my hobbies for work, so I jumped at the chance to work on this. Without getting too much into technical details, here is the basic approach used to simulate a catenary. Each cable is divided into an equal number of segments. The mass of each segment is assumed to be concentrated in discrete points at the endpoints of each. Tension, gravity, and air flow apply forces to each of these points. Applying Newton’s laws of motion to each point produces a large nonlinear system of equations, which, when solved, gives the shape, speed, and tension in the catenary. The tension at the end of the cables then produces an equal and opposite force to whatever they are attached to, like a kite. The overall fluid properties (a.k.a. flowfield) and the motion of bodies other than the catenaries in the simulation are handled by the computation fluid dynamics code.

To test it out, I modeled my Barn Door kite and set up two catenaries: one for the bridle + kite line, and the other to model a tail. For now, the kite is assumed to be rigid in the simulation, and the bowing of the horizontal spar is built into the shape. The line is 200 feet long, and I made the bridle as close to the real 5-point setup as possible, with the mass and properties of the bridle and line intended to be similar to 200-lb-rated dacron line. In the simulation, the kite is flown in a steady, uniform, 7 mph breeze. I had to estimate the center of mass of the kite. At first, my estimate was too far back, resulting in the kite spiraling out of control:

Attempt 1: aft CG makes the kite unstable

This was a little surprising to me, because I was under the impression that an aft CG is always good for a kite. I guess there is actually a limit to that. The next test moved the CG forward, closer to the horizontal spar. That fixed the stability problems, resulting in a nice smooth simulated flight:

Attempt 2: CG problems fixed, resulting in stable flight

Encouraged by that success, the next step was to simulate KAP. An additional point mass of 14 oz was added 50 feet down the line to model a KAP rig. The results are kind of interesting. The shape of the line with the point mass looks right based on my experience with real KAP. The kite is also a bit less stable with the extra weight on the line, which is also consistent with my experience. The high-frequency “wobbling” motion of the kite happens in real life too, at least with the Barn Door design. My other kite, the Mini Dopero, doesn’t do that, so it might be interesting to try that kite in the sim too.

Kite aerial photography simulation

So what’s the use of this simulation? I’m not totally sure. Qualitatively speaking, it seems to produce results that are consistent with real life. CFD is computationally expensive, though; each of these simulations took a dozen or two hours on a couple hundred cores of a supercomputer. For now, they are somewhat limited in that the kite is assumed to be rigid, but some flexibility could be included in the sim using this CFD code (maybe not full sail billowing, but at least spar bending). Turbulence and gusts could also be included. For someone with the resources available, this type of simulation could maybe be used to study how sail shapes and mass properties affect kite stability. For now though, it was mainly for fun. I hope you enjoyed these videos!

Smooth Winds at Point Lookout

It was late November, almost four months after my first KAP session. Nearly all of my outings to this point had been two different parks, and mostly just trying to get the kite really high to take a picture of the landscape. I decided it was time for some variety, so I headed down to Point Lookout, the very end of the western peninsula of Maryland. There is a lighthouse at the end of the peninsula, and I was excited to have an actual subject for my photos this time.

Unfortunately, when I got there, I soon realized that was not to be. The last couple hundred yards of the peninsula were blocked off, as renovations of the lighthouse and other buildings were in progress. The wind was blowing from the east (across the peninsula instead of along it), so there was no chance of flying the kite over the lighthouse to take pictures. I could have still aimed the camera that way, but then it would have been pointing into the sun, and the pictures probably wouldn’t have turned out that great.

So instead, I decided to take pictures back up the coastline to the north. There was a boat close to the shore that should look nice, if it would stay there anyway. Besides, then I could see what the beach area, which I know well from the ground, looks like from the air.

With the wind coming from the east, there was only a very small area to launch a kite. The edge of the beach is covered in rocks, but there was a space with some sand where I could set up. Some fishermen were in the area, casting their lines down into the water while I hoped to keep mine up and out of it! There is a picture of the area where I was flying below, taken by the KAP camera when it was only about 10 ft off the ground.

The wind was about 10 mph and pretty steady, so I selected the Mini Dopero for the flight. I prefer this kite when there is enough wind, since I can set it up and have it in the air in just a couple minutes. It turned out that having such a small launch area was no problem at all. With the smooth sea breeze, flying the kite was as easy as setting it up and letting it go! No long-line running launch was needed to contact stable air as is often the case inland. In fact, if there is one term to describe this session, it is easy! Flying over the water was a new experience for me, but the wind was so smooth that there was never a concern about losing the rig. I should fly here more often!

With such a smooth breeze, I was able to attach the KAP rig less than 50 feet below the kite. I knew from past experience not to put it much closer than that, since it can cause stability issues and make for “interesting” landings. I didn’t bring my good camera for taking pictures from the ground, but I was able to snap the one you see on the left with my phone while the kite was still pretty low. Everything was soon up and away with little effort.

Like I said, the flight was very smooth, but that doesn’t mean the camera didn’t swing around a bit. One thing I like about an AutoKAP rig (in my case, just a fixed rig with an intervalometer) is that the swinging can actually be a benefit; though most of the time it results in pictures that are blurry, poorly composed, or with a severely tilted horizon, every once in awhile it turns up some good ones. Take, for example, the pictures below. Luckily for me, the boat remained nearby the shore for almost the whole flight, which added a nice extra element to some of the pictures. In these ones, the camera was swinging downward just as the shutter went. As a result, the boat became the main subject, even though that wasn’t planned.

A boat offshore on the Potomac side of Point Lookout

There were also a few times during the flight when the wind reduced by one a mile per hour or two, the kite stopped pulling, and the line became a somewhat slack. It wasn’t enough to be concerned, and I was ready to wind it in very quickly or even run the other direction if needed, but it never ended up being a problem. A slightly more forward tow point would have helped. Eventually I got all 700 feet of line out, let it take some pictures, and then started winding it in again. Here are a couple more of my favorites.

Left: The boat nicely framed in the shot from a few hundred feet up. Right: View of Point Lookout from several hundred feet above.

The boat did end up being a nice element in a lot of the photos, like the first one above. The second one shows the beach area, which is shielded by some man-made rows of rocks out in the water, presumably to reduce the impact of waves and currents on swimmers. The fishing pier, a Civil War-era fort, and several other buildings are also visible from this altitude. Point Lookout actually has a rather interesting — albeit somewhat morbid — history dating back to the Civil War and even before. You can read more about it here:

Point Lookout State Park History

I’m looking forward to flying here again. Hopefully next time the renovations will be done, and I can take some pictures of the lighthouse and the other buildings at the tip of the peninsula.

Back to Chancellors Run Park

A couple weeks since my last outing, the leaves on the trees were a bit more colorful, and Chancellors Run Park was calling me for another KAP session. My goals for this time out were:

  • Take some pictures towards the north, where there should be some interesting things to see.
  • Capture some Fall colors.
  • If there was time, also take some pictures towards the south / southeast, which I hadn’t done the first time.

The weather forecast indicated that the winds would be best in the morning, so that’s when I headed over. When I got there, I went to the same softball field as previous time and set up the Barn Door kite. The Mini Dopero probably would have worked too, but I wanted to use the new one. The wind was gentle-to-moderate, so in the upper part of the Barn Door’s range. In this wind, the big kite was easy to get in the air. After flying for several minutes to be sure that the kite was trimmed and flying steadily, I attached the KAP rig and started the CHDK script to take pictures.

Overall, it was a pretty good flight. There were a couple times where thermals appeared, and the kite went to a very high line angle, but there were no loops or dives. The most nervous part of the flight was when the wind became stronger for several minutes, the kite flexed and billowed, and the drag pulled it down to a very low line angle (maybe 20 degrees). A few hundred feet of line were out at this point, and I had to keep walking around to keep the long outstretched line away from trees, stadium lights, and the back fence of the softball field. Thankfully, eventually the wind relented and the kite climbed high again. The people in the spin class in between the softball fields must have gotten a good look at it while it was low! I hope it wasn’t too distracting…

Eventually, I got all of the line out and got some very nice pictures to the north, one of which I currently have as the cover photo of this website! There were some Fall colors, but really they just don’t get as brilliant here as they do in other places, even a couple hours to the north. Oh well. With the year dragging on towards winter, the sun was fairly low in the sky and cast long shadows on the ground below. With the camera high in the air, Lexington Park, California, the Patuxent River, and the Gov. Thomas Johnson Bridge were all visible, making for a very nice representative view of Southern Maryland. You can see some of those pictures up near the top of the page.

After bringing the kite down, I had a little time for another flight to take pictures in the other direction. The sun was in that direction, so I wasn’t expecting great quality, but some of them did come out decently. Due to time, I didn’t fly as high. One of the better ones from that short flight is posted above. You can see all my aerial photos from this park in the Chancellors Run Park Aerial Photo gallery.