Multi-Dowel Barn Door Kite:
Testing the Strength
by MBK Flight Reporter: Craig E.
(Shedd, OR, USA)
I love Hawaiian shirts!
As of yesterday, I had flown a total of three short test flights with my Multi-Dowel Barn Door kite. This is due to my job, recent move, and spending my remaining fractions of time with my lovely bride, Sarah and Brennan.
Despite the busy schedule, I have been able to make two very short flights that were really just for making sure that this behemoth barn door will actually fly. We have lots of trees and power lines here in Shedd. It did fly, but the trees were looking very hungry that day so I reeled it back in to safety.
I also had the opportunity to make a short flight at the local community college. This flight was not the greatest due to low winds and a baseball game roughly 100 feet down wind. I was only able to get it up to about 50 feet or so before the wind died. I was, however, able to infer from this flight that it would be at least as good in light winds as it's smaller ancestor.
(A note to readers... The e-book Making Dowel Kites will be handy if you decide to have this kind of experience for yourself one day - Tim P.)
This time, I followed the plans pretty close with a few exceptions...
First off, I used small pieces of oak for splices rather than the "drums" that were called for in the plans. These splices began life as a piece of 1"X2"X10" scrap oak. Using a drill press, I drilled several 3/8" holes through the 1" side of the wood. These holes were spaced roughly 1" apart.
Next, I made cuts exactly between the holes which gave me several 1"X1"X2" sleeves that would later be rounded off with a belt sander for looks.
These were then glued to one of the spars waiting to be joined. I must admit that it works very nicely with a very clean look. It also saves a couple ounces overall since the splices only weigh 1/2 ounce or so compared to well over an ounce for 18" of 3/8" dowel. These could be made with a hand drill and a wood saw if that was all you had access to. I would strongly recommend using this system especially if you have access to basic woodworking tools. If this is not the case, the "drums" work and are flight tested.
I also modified the corner strap system to make the sail tension adjustable by means of a trucker's hitch. It's easier to explain the system using pictures. I was having issues with the strings not staying taped to the sail when built as per plans. This made it a bit more complex, but the sail tension is now rock solid!
Construction was pretty simple with my $1.00 sheet of .7 mil plastic drop sheet. I used 3/8" oak dowel, but I'm thinking about moving up to 7/16" since these bend a lot in moderate winds.
I am surprised at the durability of the .7 mil sheet plastic even in the 15 mph winds that I was flying in. I only used one layer, but it's big enough to carry the extra weight of two layers of plastic.
Using two layers helps with durability when the black tape accidentally contacts the sail. My current sail has a number of small holes from stray pieces of tape that I use to lash the spars together. These small holes are inconsequential due to the huge amount of sail area. It boasts roughly 40 square feet of sail area!
The total cost was around $7.50 USD. That includes the tape, plastic, and 6 dowels. I already had the oak for my splice joints so this was of no cost to me.
Building the frame was not terribly difficult, but the sail took the entire width and length of my kitchen floor to layout and cut. This is of course after I relocated the dining room table to the wall.
After all this, I was barely able to get my sail laid out flat on the floor with just enough room to walk around it. Of course, I folded it in half to get symmetry when I cut it out.
Taping the edges was very easy and quick with the 1 1/2 " cellophane tape. On the other hand, building and attaching the sail pockets was a bit difficult but certainly doable. I never got around to re-enforcing the bridle holes. This step is not vital, but it will make the sail last longer.
FYI, I am more than happy to share my pictures, methods, and knowledge with anyone wanting to explore the above mentioned options.
Now to the flying!
The first flight was short, and iffy but it flew in some pretty light winds with the help of some thermals. Even in these light 5 mph winds, it pulled pretty hard. It pulled so hard that I was hesitant to fly on 50 pound line in any kind of wind. I ended up bringing it in after a few moments because the wind was pretty light and there was no sign an increase.
A few days later, I flew it once again in the front yard, but with very limited room between the walnut tree and the pear tree. There really isn't a good place to fly here in Shedd unless I want to fly from the side of the road or something.
This was mainly an exercise in setting up and making sure everything was still there and useable after being rolled up for three weeks. I have trouble keeping the bridles untangled, so I usually take the lines completely off the spars and just re-tie them once I get the frame and sail laid out. It's not too much trouble, but I need to get a system sorted out before I get too frustrated and move on to kite with an easier setup.
Fortunately, my 1000 foot spool of 150# line which I ordered through an online site called Emma Kites showed up just in time. $14.00 is not a bad price for that much line! This was a great time for me to rebuild my spool after the 50# line crushed all the 1/4" dowel cross members. I don't think any kind of line will bend the six 1/4-20 bolts that took the dowels' place!
It was very nice to not have to worry so much about my line breaking. I have no idea when I will be able to get all that line out at once, but I'll find a way! Maybe I will get some box kites up in train?
We chose to fly at Willamette Park again but the wind was very strong for the spars. Nevertheless, I managed to get it rigged and flying. There was a tendency to lean to the right just as the Dowel Barn Door did. This was easily fixed by adjusting the bridle about two inches at a time.
I finally got it to fly true...ish after my lovely assistant attached about ten feet of my crepe paper to the higher side. Even with the crepe paper, it still leaned about 10 degrees to the right with more pronounced dives during a gust.
In fact, it was really just too windy for this kite to soar at altitude. While observing it, I noticed that the kite had some issues deforming in the stronger winds. It didn't break my splice which is was really cool.
Altogether, it was up for only 20 minutes or so due to excessively strong winds above the trees. I think the winds were around 20 mph, but I don't know for sure.
Although it was possible to move the tow point for higher winds, I chose to keep it set for moderate winds because the winds above the tree line were likely to be too strong. On the other hand, the winds below the tree line (75'-100') were very gusty so my kite would cycle from pulling very hard to drifting toward me because the tow point was too far forward at that moment.
I was able to get above the trees and into some smoother air for a few moments toward the end of the flight. This was after re-adjusting the bridle to get some climb out of it.
It was fun to see, but the winds were very strong and threatened to break the spars on more than one occasion. This would have sent the kite into the top of a tree that I simply would not be able to (legally) climb because I was in a public park. Bringing this kite back in was a real workout for my arm as well.
I guess the maximum altitude was close to 200 feet maybe less. It's hard to tell when the kite is so big.
Being Father's day, my wife came along which would make this an "adventure date." She played the role of in flight photographer so I had plenty of pics to choose from. In view of the "date" aspect, I wanted to keep it short rather than getting too involved in my kite flying and ignoring her! Her company is always welcome on these outings.
I hope to get up in some reasonable winds that are better for thermaling. Maybe I will get it all the way up to 1000 feet! Just don't tell the Feds. Besides, the FAA really doesn't care about kites, but being an ultralight enthusiast, I care. I can only imagine the damage that a very large kite would do to an aircraft.
I will write again when I have a nice long flight with this Multi Dowel kite. I can certainly see some KAP opportunity for adventure with this monster of a kite!
Download the e-book Making Dowel Kites here.
E-book special of the month (25% off)...
e-book takes you step-by-step through making a 120cm (4 ft)
diameter Parasail kite. This kite performs well in gentle to moderate
wind speeds. That's from 12 to 28 kph or from 8 to 18 mph. It pulls
hard for it's size, so should not be flown by very small kids!
Every kite design in
the MBK Soft Series satisfies the following points...
- Materials are
plastic sheet, tape and line – and nothing more!
- Tools are a ruler,
scissors and a marker pen - and nothing more!
- All cuts are
along straight lines.
For the greatest chance
of success, I make recommendations regarding the materials. For
example, the type/weight of plastic, type/width of tape and line
type/strength. Close enough should nearly always be good enough,
since the design is well-tested and should be tolerant of small
differences from my original.
Get the e-book for making the MBK Parasail kite. After making your first one in plastic and seeing how it performs, you can try soft Tyvek or rip-stop nylon for your next build.
The e-book is a PDF file - which means printable instructions to refer to while you make the kite. It also means convenient off-line access if that suits you better.
Jul 19, 17 06:00 AM
This previously published page covers the basics - an intro if you are curious about the idea of getting pulled across a flat dry surface on a wheeled board!