Wednesday, August 31, 2011

Awesome New Project!

     So, my newest interest is the study of light or for that matter the entire Electromagnetic Spectrum. Putting it that way sounds incredibly boring and dull but if you know me then you know what kind of levels I can and will take a simple science to. As of right now I have some serious equipment on order, on its way to my house, that will definitely take this area of physics to the extreme. I will get to that later.
     I will start my mini physics lesson with the visible light spectrum. It makes up an incredibly small portion of the entire EM spectrum.

Everything from X-rays having an extremely high frequency to radio waves having extremely low frequency are made up of the same "material" called photons. However, as humans we are only able to detect a small interval of these frequencies with our eyes known as visible light. Keep in mind that "black" is the absence of light and "white" is the presence of all visible light frequencies "mixed" together. Everything we can see that has color is reflecting (NOT emitting) certain frequencies of light. For instance a flashlight(that is emitting all colors of light making it white) shining on an object that appears red is reflecting only red colored light and is absorbing all the other colors. What happens to all the other colors? The object absorbs them in the energy form of heat. This is why black objects that have been in the sun for a while become hot. Since black doesn't reflect any light, all of that light energy from the sun is absorbed and stored as heat, as opposed to white objects which reflect all frequencies of light and therefore no energy is absorbed. 

     Here is a chart that displays what colors of light make up other colors. Green, Red, and Blue are the Primary LIGHT colors. With them we can make any other visible color. Except black or course. So, if I were to emit a perfectly green light at a perfectly red or blue object, the object would absorb all the light as heat energy and heat up. If I were to shine that same green light at something green, then the object would reflect all of that light and remain a certain temperature. What does perfect mean? Well, a perfect red light would have a wavelength of 700nm (nanometers). Blue is 470nm, and green is 530nm. 

     Imagine if you had a device that could emit a perfect and consistent frequency of light(flashlights emit all frequencies of light so not too much help there). You could shine it on objects that you know would absorb all or most of its energy and transfer tons heat energy with light! Even to the point where the object couldn't handle that much energy and combusted! Well, these devices are actually very common and they are called lasers.

     Lasers(Light Amplification by Stimulated Emission of Radiation) emit a single wavelength of light, and the light is concentrated into a very little diverging beam. As you probably already know, lasers have a million uses but some of those uses(that I'm interested in) require a very high powered laser. To give you an idea of what a high power laser is; some companies actually use lasers to cut material for products. They can even cut through thick steel! Just remember that all that energy is from a simple beam of light or in some cases Infared, but that has just a slightly lower frequency than light.
     The lasers you can buy from pet stores or office supply stores are lasers that have a power of 5mw(milliwatts) or less. These are called class IIIa lasers. Their only use is to project a colored dot on a nearby surface. Like the one pictured above. These have applications such as pointing out something on screen or tricking your pet into thinking is a small animal to chase. You may have seen or heard of people popping balloons or lighting match heads with lasers but those lasers are MUCH more powerful. 11 times more powerful to be exact. Yes, with our atmosphere and its contents it will normally require a laser of at least 55mw to burn an object that is darkly colored. This is because the heat energy being generated will be transferred to the air around the object, and in order to "burn" the object must absorb energy faster than it can dissipate it back in to the atmosphere.  For instance, if you wanted to pop a balloon you would need to color a black spot on it so the balloon can absorb more energy. However thats if you only had a 55-100mw laser. What if you had a laser that was 100 times or more powerful! I mean, a laser so powerful that it has laws against their usage and transportation and is in a whole separate class! A class IV laser means that the output power is 500mw or more(this is the highest class of lasers).  

     Like I said earlier, I would be taking this science to an EXTREME. So, I've ordered a class 4 laser which will be arriving two days from now! It is has a peak output of 600mw and will be able to burn just about everything thats not white. In which case I will color it with a sharpie. If you are familiar with the laser world, you would probably ask if it was actually 600mw and I would tell you that it is a Laserglow Technologies product. So yes it definitely will attain 600mw. Its called the Hercules-500 

     It requires a key to power it up and safety glasses are a must! I've also ordered the detachable lens along with the tripod mount, AC power adaptor and extra safety glasses. The laser it self weighs over 3 pounds and has its own cooling system with an auto shut-off if it starts over heating. And for us laser fanatics… 532nm, Beam divergence is .8-1.2 mrad. Or .08-.12 mrad with 10X beam expander. 2.5 watt Pump diode. And 100% duty cycle! 

   All of this together makes this the most powerful portable/handheld laser available(its in the Guinness book of world records)

I will be posting many follow up videos and pictures once I get it. If you have any ideas of stuff to burn, leave a comment!

Wednesday, August 17, 2011

Air Cannon!

So for my first blog, I figured I would use my air cannon project. I built this a while ago but I still pull it out of the garage almost every weekend to have some fun. 

     I got the idea to build this huge air cannon from my high school physics teacher. He built one out of steel pipe and used it to launch a bean bag a couple hundred feet in to the air. The air tank held 230 cubic inches of air. I of course wanted to build one that would put his to shame so I designed one that held 750 cubic inches of air (not the one pictured). It had a single tank and a 6ft barrel that was 1 inch in diameter. It was constructed completely out of scd 40 pvc with the exception of the brass ball valve and a steel pipes leading to the ball valve and the brass fittings for the gauge and the fill valve. I used 25 gal air compressor to fill the tank to 135 psi. I was a little worried about the "T" pipe fracturing so I covered it in electrical tape to prevent shrapnel.
     For projectiles I used half inch PVC with a steel lug in one end all wrapped electrical tape to attain a snug it in the barrel. These projectiles, when fired upwards can get so serious altitude. I'm to lazy to calculate it out right now but at about an 80 degree angle, I got flight times of 13 seconds!

     However It was a must to try a horizontal test for sheer power. A 2x4 seemed like a good test subject. As you can see from figure 1a it pretty much spit it in half! 
figure 1a

     This whole cannon idea has been coming along awesome so far, but I've always wanted a cannon that actually looks like a "cannon". So I started to plan out a new and very improved air powered masterpiece. My sights were set on a cannon that was so big that it had to be mounted on a carriage with wheels to even move. It also needed to have a barrel wide enough to fit baseballs, gatorade bottles or any other thing that may come about…like impact detonated projectiles. ..maybe  I Figured it also needed to have excessive power if I ever wanted to add barrel length or launch something really heavy. I decided to use a twin tank design to maximize the volume and keep the length in check. I planed on using a 10 foot barrel and at least that length in tank space so my design incorporated a fold between the barrel and the tanks. The new tanks are 6 feet long and 4 inches in diameter totaling 1809 cubic inches! That's a lot of air when its filled to 140+ psi! Each tank will have its own fill valve and gauge. This way I could use one tank at a time and hopefully get a few shots before it needed to be refilled. I still with a ball valve trigger system because the electric solenoids are only rated up to 80 psi. 

new tank compared to old.
     The new tanks are huge! By huge I mean probably too big…but thats crazy talk…OVER ENGINEER EVERYTHING!  When I built the smaller old one, before I attached it the barrel, I filled it up to 100 psi to check for leaks and then quickly released the air to feel how much force it could put out. It gave me a nice push but not enough to be impressive. I decided to do the same test on the new tank. Assuming that it would have a little more force, I took a more defensive stance. When I flipped the valve, the force of the air rushing out was enough to throw me off my feet and push me a good 3 feet through the air!  

     With all of the main components made the last step was to fit them all together, witch can be easy if the barrel was a couple feet long and I could support the entire weight and fit the two pieces together at the same time. I ended up having to suspend all the pieces from cross beams and slowly move all pieces together. After all the pvc was in place, I built the chassis and the wood cross sections between the tanks and the barrel. I got the wheels from an old circus wagon. They are completely lined with steel and are mounted on a solid 1 inch thick solid steel axle.

     Here is the finished product! I wrapped the barrel and some other parts in electrical tape, as I have found it really helps prevent shrapnel if anything were to explode. The cannon has exceeded my expectations and I will probably never get bored of it. I built this when I was 16. I'm 19 now, and still roll it out of the garage almost every weekend I'm home from college. The usual projectile I use is a gatorade bottle filled with water. How ever I have filled them with concrete. I have also shot railroad spikes(several at a time like a shot gun), hockey pucks(I glue 4 or five together to make a piston shape), long poles, flags, small impact detonated explosives, base balls, and even tanks of propane in to a bon fire! I have run some numbers on this thing and taken a few measurements… average projectile velocity is around 360 miles an hour! How ever that is the speed of a "full" gatorade bottle. Using that velocity and knowing the length of the barrel, I calculated the acceleration and used that to find the force that is exerted on a full gatorade bottle. So, in theory if I were to launch an empty gatorade bottle, it would accelerate much faster. How fast you ask? Well, the muzzle velocity would be somewhere around 1200 miles an hour. Almost mach 2!  

                                                            Here are some of the videos I've made…