Box Kite: A Single Brace Prototype

Box Kite: A Single Brace Prototype

Here is a box kite I just made. There are tons of kite plans online, but my kite has some major differences.  My box kite just has a single central brace instead of two end braces. I also used balsa instead of spruce or pine.

These changes from the norm created issues, which I dealt with, to create a really small and light weight flyer.

Traditional, flat diamond-shaped kites are harder to manage in the wind. As the wind speed rises, they'll need a longer and longer tail. Tails stabilize kites by adding drag (it's not really the weight that helps).

I wanted to design a kite that was easy to keep up and that could handle rougher winds without the need for longer and longer tails-all in as small a kite as possible.

This led me to a box kite, because multi-planed kites are easier to fly and usually don't require any tail.

I also wanted to go extremely light and small. I replaced the usual spruce and pine with balsa wood.

Weight per cubic foot

Spruce = 28lbs

Pine = 26-45lbs

Carbon Fiber = 106lbs

Aluminum = 168lbs

Balsa = 4-24lbs

As you can see, balsa is much lighter than the other materials. You'll notice that carbon fiber is really, really heavy! The secret to using light weight materials is actually a misnomer: they're really strong for their used size. 

Steel is heavier than aluminum but an aircraft part made of aluminum the size of a pencil can be redesigned and made out of steel the size of a toothpick. Making an aluminum part as an exact copy in carbon fiber doesn't save you much weight, but you can make it thinner and in a different (smaller, thinner, shorter) shape and that's where the real weight savings begin to appear.

My redesign? Well, I didn't just replace the spruce with balsa. I also radically modified the traditional box kite design by getting rid of the end braces and creating a single, central brace.

Wind passing over a plane wing creates lift. An airplane propeller creates wind over the wing. The Wright Brothers took box kites in a cellular / modular design and added an engine to create wind on demand. Boom: a hard to steer airplane!

Then the Wright Brothers came up with something awesome: make the boxes super-flexible! This really helps catch and keep the wind.

Instead of a rock solid brace at both ends of the box, my design has a slightly flexible central brace! It will catch the wind more easily. Also, I'm now using lighter wood-and a lot less of it. [edit: I oddly used heavy newspaper instead of lighter materials like plastic grocery bags to cover this].

Another change I made is to scale down the traditional box kite measurements. Box kites were used to lift things like emergency radio antennas in life rafts. Almost and other box kite plan you'll see online the standard 40" long rail variety or larger. This box kite is only 10" long!

A (Braces)               17"     8.5"     4.25"    2.125"    1.7"

B (Rails)                  40"      20"        10"            5"       4"

C (Skins)                 12"        6"          3"            1.5"    .75"

D (String offset)    6"          3"         1.5"          .75"    .375"

E (End String)       60"        30"         15"         7.5"    3.75"

F (Offset String)    50"        25"         12.5"     6.25"    3.375"

Basically, I just scaled down everything. I came up with the above numbers and used the third column-except for the string lengths (E and F) leading to the bridle.

Balsa cuts and saws very easily.

I notched the center brace components using the little Xacto saw and then just cleaned up the notch with an Xacto blade.

My new, experimental one-of-a-kind Logusz Brace. It joins together tightly even without glue.

The other joints were notched as well.

Clamps! I highly recommend you don't do what I did by using heavy clamps. Also, don't use alligator clips because they'll damage the balsa. Go online and order some "panel clamps" for $2 each. They're perfect for this type of thing and are made for clamping thin bits of metal together for welding. Mine are arriving in a few days.

To true up the frame I used the paper skin to pull things into shape. I wrapped the end around a rail with glue and let it dry. This let me pull really hard on the paper and thus keep things taut and straight.

Here's the first joint that anchors the skin. I let it dry before continuing with construction so I could pull the paper tight.

Notice the center brace isn't (yet) straight like a + sign. It will be!

Strings for the bridle. A string passes through a ring and connects two rail ends. The other string also passes through the ring and connects to two points in the halfway point of the opposite ends' paper skin.

The metal wire shown is pulling on the clamp, which makes the central brace straighten out into a perfect "+" sign shape.

Nice and straight!

A bread tie used as a glue brush. I ran it between each rail and the paper skins.

I put 4 layers of transparent tape on the skins where I drilled holes for the strings using apin vice drill.

Curved tweezers / forceps are indispensable for knot tying.

Both strings get looped around a plastic ring twice. This forms a bridle which self adjusts, allowing the kite to stay with the wind-eliminating the need for a tail.

There she is: a single brace box kite! Single, central brace. Quarter size balsa. Ultra light. Tail-less.

I ain't got no tail either... but then again, I can't fly. Meow.

Gauss Gun

A Quick Gauss Gun Post

In a simple Gauss Gun a steel ball rolls toward a magnet with two balls on the opposite side of it.

The ball nears the magnet, which pulls on the ball and increases its speed.

The ball slams into the magnet, which transfers the energy and momentum of the ball to the first ball on the other side. The first ball transfers this energy and momentum to the second ball-which goes shooting off.

The last ball shoots off at a much faster speed than the original ball because of the increased acceleration provided by the magnet as it "grabbed" the original ball when they got close to each other.

The magnet with two balls on one side is a stage. You can set up many, many stages in a row to create a chain reaction with a pretty fast moving ball shooting out of the last stage.

Rolling friction, aerodynamics and the magnets pulling too hard on the secondary balls can steal some of the energy and momentum by not letting the last ball go easily to the next stage. A way to counteract that is to use electromagnets (coils) that shut off right as the stage receives the incoming ball.

I came up with an easier solution: have the first of the two balls be non-magnetic! It acts as an isolator between the magnet and the second ball that gets launched to the next stage.


Another thing that steals energy and momentum is if the magnet slides backwards a little to meet the incoming ball a little earlier. The solution: I taped the magnets down so they wouldn't move.

Experimenting with different sized ball bearings, different numbers of them and different strength magnets all have noticeable effects on performance. As do the spacing between stages.




Here's some simple performance test videos I made:

I found that K&J Magnets has some medium sized magnets and balls that work even better than larger ones. I had great results with the quarter inch (D44) ones:

K&J also have an awesome blog with tons of projects like this (which include links to their industrial products if used in the experiment). Very cool! 

K&J also explain the science behind Gauss guns (and magnets in general) without delving needlessly deep into Newton's Second Law of Motion, as most explanations online do. Hint if you read up elsewhere: a euclidean vector is just an annoyingly complex way of denoting an arrow. "The ball shoots that way!"

If you're interested, F=MA , Force equals Mass times Acceleration. You have to kick heavier balls harder to get them to go the same distance. What's important is that Acceleration here is just the initial jolt/kick, just like the better quick on/off electro-magnets in a coilgun! It sets the object in motion. That is all (and that is the best part). Newton's Third Law of Motion is the equal and opposite reaction one: which is why taping the magnets down is better: no jolting back and forth. The tape helps conserve energy.

Newton's First Law is just the one about inertia: objects at rest or in motion stay that way unless acted upon by unbalanced force. It's why the balls eventually stop instead of blasting a hole in the universe.

If you add a bunch of stages you might just get some cool results, but you might shatter a magnet or put a hole in something! Eyewear is a must! All the laws take their toll on the Gauss gun, especially a simple one like this.

However, at some point I'm going to try 20 stages firing .177 pellet gun bbs. I have a feeling their reduced mass (M) will insurmountably hinder optimal performance.

Carl Friedrich Gauss worked on a lot of number theory mathematics, but he also founded the "Magnetic Club" in 1883. He has a unit of measure (the gauss) named after him. It measures magnetic fields, and Gauss formulated ways to measure the properties of magnets using only the simple concepts of time, mass and length. Specifically, he came up with a better way of measuring the oscillation of a magnetized needle to measure magnetic field intensity. This used to be measured in a unit called the gauss, but they changed (in 1932) the term gauss to refer to electromagnetic induction, and field intensity was then notated in units called oersteds--Hans Christian Oersted discovered electromagnetism in 1820.

Magnets actually have different gauss values for their different fields (surface, residual flux) and all things being equal a physically larger magnet will have a lower surface field! So, magnets have various other ways of denoting their "strength". The easiest is pull force: how many pounds can it lift or pull?

Another is the N number, which is derived from a magnet's MGOe (Mega Gauss Oersted) value. Neodymium rare earth magnets range from N35 to N52. This is the amount of stored energy (energy density) in the magnet.

Speaking of energy, check out what else these magnets can do:

The magnets used in this post were all N42 magnets. The white part of the gun was just a piece of ceiling molding. Just scraps.

I need to borrow the Gauss gun just one more time, Meow!

Sun is NOT the Center of Solar System: A Lesson in Elliptical Orbits

The Sun is NOT the Center of Solar System: A Lesson in Elliptical Orbits

We are going to cover elliptical orbits, ellipses, creating ellipses, sine and cosines, and Johannes Kepler's Second Law of Planetary Motion with an ultra-simple, easy to understand method using a piece of string! 

Kepler was trying to prove that planets sweep out equal areas in equal time periods...except he kept getting errors as he attempted to calculate the orbit of Mars. He tried fitting his calculations to a circle shaped orbit and an egg shaped orbit: no luck. Then he tried an ellipse, succeeded and also proved the sun wasn't at the center of the planets' orbits!

Our sun is not the center of the universe. It is not the center of our solar system. The sun is at one of the two foci of an ellipse, the other focus is an empty area of space. The foci are like two centers of two circles joined together into a blob. BUT THE orbits are so close to circular looking that diagrams of our solar system are basically circles within circles with our Sun at the center (but technically a smidge off). It's called the "barycenter".

In fact you can create a circle by bringing the two foci together-and we'll do that after learning how to easily create ellipses with a piece of string, a compass and two pins. This piece of string will also easily show us Kepler's law of planetary motion: something that is an absolute mathematical truth...but looks totally untrue to human eyes.


Let's start by marking the length and width of the ellipse we want:

Put a pin at each end of the length and connect with a string:

Set the compass to the distance from the center to a length end point:

With the compass set to the distance from the center to an end point of the length, put the sharp part onto a width point and draw marks where the compass-swing hits the line of the length.

Take your pins and string and stick them into the compass marks.

Take pencil and draw while keeping the string pulled tight. There is your awesome new ellipse! You'll notice that the string forms a triangle, kind of like the sine/cosine triangle in the circle from a few posts ago about Lissajous Figures. We'll come back to this triangle in a moment, but first let's Reverse engineer this ellipse into a circle.

As we move the two foci closer and closer together the pencil and string triangle sweeps out a shape that is more and more circular. Put the pins in the same hole (or just use one pin) you'll get a perfect circle.

Back to the triangle sweeping:

Kepler's Second Law of Planetary Motion says that as a planet sweeps along its orbit, in different parts of the ellipse (even the smaller ends) the area it sweeps out is always equal to any other area it sweeps out given the same time to sweep. Two seconds of sweeping in the little end gives the same area as two seconds of sweeping the bloated middle.

That sounds and looks wrong, even in fancy computer animations...but just remember our string triangle: it moves all about and changes angles as it's dragged by the pencil but its overall length never changes. The string doesn't get shorter or longer. The base of the triangle never changes as long as the pins don't fall out. The length of the two other sides of the triangle always add up to the length of the string.

Sameness.

Couple the sweeping in an ellipse with the sine/cosine triangles...

...and add a few more little trigonometry bits like tan and arctan and you get the field of calculating xy ballistics trajectories for non-powered projectiles (bullets, rocks in a catapult, etc.).

Wait, I can use a piece of string to calculate the path of birds?!?

 They'll be non-powered once I gnaw their wings off.

Great Balls of Carbon!

Great Balls of Carbon!

 ...ok, they're actually teeny-tiny charcoal spheres.

These are little black balls I found inside of an old hard drive I just took apart. They are charcoal. Activated charcoal pellets to be exact. Like tiny versions of the charcoal briquettes you might use in your barbeque grill, which were invented by Henry Ford.

You burn something with carbon in it (most things in the universe) while providing lots of oxygen. The result is very porous charcoal. The pores are shallow like the dimples on a golf ball. They increase the surface area and help soak up poisons and other contaminants like gases in the air.

In hard drives they're in a little cup with a vent on one side and gauze on the other. This acts as an air filter for the hard drive. I had the same setup for my aquarium when I raised pufferfish! A gauze pouch with charcoal pellets for cleaning the water.

SiliCON vs SiliCONE  vs Carbon

The carbon pellets are also super bouncy. Like, oddly bouncy. Way more than the polymer ball we made a few posts back. That surprised my, but a quick glance at the Periodic Table shows that carbon lives right above silicon, which you'll remember from the non-Newtonian fluid and polymer post and the fast that it's what makes Silly Putty so bouncy...well, that's silicone with an "e" at the end polymer made from silicon. Carbon forms much more stable bonds than silicon, but it likes other carbons to bind to. Silicon likes oxygen, and although it's less stable than carbon bonds silicon plenty of molecules-great molecular subunits linked together (very bouncy). Silicone rubber (which is a silicon polymer) has a Young's Modulus of 0.001 and carbon is less elastic at 4.1.

Balls bounce one way, balls bounce the other way. Meow. 

Here is one on the xyz stage of my microscope. The white disk is actually the other side of the black cup/filter assembly it was in with a zillion of its pals. A little ways below I have a better photo of this cup.

Here's some various videos made with 3 different cameras, a very nice microscope and some really terrible out-of-sync lighting. This gives a good sense of their miniscule size.

The very same from my previous video:  little black balls I found inside of a hard drive I just took apart.

They are charcoal. Activated charcoal pellets to be exact. Like tiny versions of the charcoal briquettes you might use in your barbecue grill, which were invented by Henry Ford.

They're in a little cup with a vent on one side and gauze on the other. This acts as an air filter for the hard drive. I had the same setup for my aquarium when I used to  raise Figure-Eight pufferfish!

In this video I put them under a very nice microscope...but with a very cheap ($1.99 used) webcam and terrible side lighting. My microscope has very, very, very good lighting for looking at slides and other things properly prepared for microscopy with the light coming from *underneath* the slide-not from the side.

Also a point of annoyance: I was testing a crappy webcam (an ancient GE model) that I bought used for $1.99. The flicker is from the LED flashlight not syncing with the webcam.

So, a lot of ugliness on this one. Check my other videos for better cameras (a big Canon in HD, but also my cheap Samsung cellphone and Nexus tablet have way, way, way better video than this GE webcam).

This video was: cheap camera, cheap flashlight just as a quick peak. On the blog post I'll put some better looking still photos.

For a $1.99 I finally have a webcam. At some point I might bash the lens off of it and point its CCD array straight into a dark container with a photo-amplifier tube / scintillator in it to create an alpha particle radiation detector. Sort of like the alpha spark detector I made a video of, only digital.

The microscope is actually very nice (stereo eyepiece, xyz stage, abby condensor, LED with electronic dimming switch and various mechanical shutters for dimming and changing the incidence angle of the light, 2000x oil immersion lens: basically all the bells and whistles and the highest reflected normal light magnification physics allows! All coupled (today only) on a webcam that costs less than a can of Red Bull, lol.

I was also holding the webcam with one hand while moving the xyz stage and focusing with the other--I'm being terribly unprofessional today. I actually have a side illuminator for microscopes that I could have used also. It has a nice (non-harsh, non-flickering light) but this was only a test and with the lousy webcam it would't have made much of a difference.

I kept changing video cameras, but kept the lousy lighting.

Speaking of old technology, I also found this cool brochure for coin operated computers for our library. Pineapple Computers!

Neat, but my computer glows in the dark!

I don't care about the black balls, but I need you to make sure none of these old hard drives have any snakes in them! Mee-yow!