Kip Hagberg, Joseph Hernandez, Spencer Herriges,
Drew McGovern and John Cameron
Table of Contents
Hovercrafts nowadays are used for multiple things; such as, transportation and military use. Though in our modern times we have refined the design for the machines to perform at the best of their limits, the first actual working hovercraft wasn’t around until the 1950’s. Before that there were many attempts to create a land based vehicle that could not only propel itself forward but to lift itself from the ground as well. The first concepts on record for this idea was done by Emanuel Swedenborg, a Swedish scientist. Original efforts to make hovercrafts appeared as hybrids, meaning that it could only operate on either land or sea and didn’t float but used air to raise the front end of the vessel to make it faster and more maneuverable. Then Sir Christopher Cockerell discovered that a high pressure air current could be trapped inside the curtain of the craft, by studying the ring of airflow when high pressure air was blown between concentric tin cans. This idea is now most often associated with modern day hovercrafts. The design was under the control of the military and was thus classified, but when the military had lost interest in the project it was declassified. Further research was then brought to the National Research Development Corporation and this produced the Saunders Roe, Nautical 1 or SR.N1, the first true hovercraft. From this original craft came the improvement and designs that we see today.
Hovercrafts work on two main principles: lift and propulsion. Lift is an essential factor because it allows the craft to ride on a cushion of air several inches off the ground. This is possible by directing the airflow under the craft with the use of a skirt. The skirt must be light, flexible, and durable all at the same time. Having the proper amount of airflow under the craft is key; too much airflow causes the craft to hover too high and results in tipping, while not enough airflow results in the craft to remain grounded. Propulsion is what makes the craft move, the source of this effect is the fan. A normal fan is not sufficient for this craft; a normal fan spins the air in a spiral shape, rather than blowing air straight back. Engineers decided to use turbines or stationary blades. The shape of the body affects the stability of a hovercraft: a larger area of base allows the craft to be more stable while a longer and narrower shape increases speed but decreases stability.
The purpose of this experiment is to create a fully functioning hovercraft that stays true to the scientific principles of a hovercraft and that would allow any of our group members to operate it, despite differing weight.
We believe that by finding the correct amount of air to enable a 4ft x 3ft hovercraft to hover, produced by 12 HP. This will then allow us to put a payload of up to 230 pounds on the craft, such as a person, who then be able to manipulate the craft how they choose.
The variables within this experiment are so; the controlled is the air displacement of 420 ft.^3 per minute, 1 HP (25cc engine), speed of air at 200 mph. Other controls were the weight of the craft at 15 lbs., skirt volume 7 ft.^3, and max lift weight of 150 lbs. The independent variable is the weight, and the dependent variable is power.
The first step in construction the hovercraft was to accrue our materials. After trolling Craigslist for several weeks, we managed to find a 25cc two-stroke leaf blower in our price range. After buying that, we headed over to the neighborhood
Home Depot ™and purchased:
● 1/8" Plywood
● 1" Solid Insulation Foam
● Liquid Nails Epoxy
● 1/4" x 2" Stainless Steel bolts
● 1/4" Stainless Steel nuts
● 3" PVC Elbow
● 3" Rubber Coupler
● 4" PVC Base w/ 3" Reducer
● 4' x 8' Heavy Duty Tarp
After acquiring all of our materials, we set out to assemble the vehicle. First, we made to body which would support the rider and the motor by sandwiching the 1’’ foam between two 3’x4’ plywood boards, using a combination of screws and epoxy. Next, we rounded the corners of the platform and sanded the edges, to prevent snags and tears on the skirt. We then drilled a 4” diameter hole in the boards to mount the blower assembly to. This was constructed by disassembling the leaf blower nozzle, attaching a coupler to the output, and then hooked this apparatus to a 4" PVC Base with a 3" Reducer, which was fastened with liquid nails (and solid screws) to the platform. To make the skirting, we cut the tarp to roughly a 3” excess for all of the sides, and wrapped and anchored it to the platform with a layer of epoxy, followed by one with duct tape to cover any possible leaks. After the liquid nails had set, we flipped the craft over and cut vent holes in the bottom, so that the bag wouldn’t overflow and pop. Another feature we added was a small, 4” wood ring screwed in through the tarp to the platform, in order to reduce the surface area of the hovercraft in contact with the ground, as well as improve its stability.
http://cnettv.cnet.com/bubba-watson-bw1-hovercraft-golf-cart-ep-116/9742-1_53-50144740.htm Bubba Watson's Hovercraft golf cart article.
http://newswatch.nationalgeographic.com/2013/04/08/how-to-build-your-own-hovercraft-in-answer-to-bubbas-hover/ National Geographic article about building your own hovercraft.
http://www.popsci.com/technology/article/2013-04/why-aren%E2%80%99t-hovercraft-more-useful Interesting article by Popular Science and the relevance of hovercrafts today.
http://www.instructables.com/id/Hovercraft/ How to make a hovercraft as per Instructables.
http://www.neoterichovercraft.com/ Major Hovercraft Maker and Distributor.
1) "Two Tin Cans and a Bit of Air." How a Hovercraft Works. N.p., n.d. Web. 30 Oct. 2012. <http://www.hovercraftmodels.com/How_a_Hovercraft_works.htm>.
2) O'Shea, Brian. "Hovercraft Physics." So How Does It Work? MAGIC!!!!!! N.p., 25 Jan. 2002. Web. 28 Oct. 2012. <http://lca.ucsd.edu/~bwoshea/personal/hovphysic.html>.
3) "Universal Hovercraft, The World Leader in Hovercraft Technology." Universal Hovercraft, The World Leader in Hovercraft Technology. N.p., n.d. Web. 28 Oct. 2012. <http://www.hovercraft.com/content/>.
4) "How Hovercrafts Work." How Hovercrafts Work. N.p., n.d. Web. 28 Oct. 2012. <http://www.replicahovercrafts.com/how_hovercrafts_work.htm>.
5) "How Does a Hovercraft Work?" How Does a Hovercraft Work? N.p., n.d. Web. 28 Oct. 2012. <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Aero_p033.shtml>.
6) Beaty, Bill. "ULTRA-SIMPLE HOVERCRAFTScience Fair Projectcan Lift Several Adults!1997 William J. Beaty." HOVERCRAFT SCIENCE FAIR PROJECT: VACUUM CLEANER POWERED, LARGE SIMPLE HOVER CRAFT. N.p., n.d. Web. 28 Oct. 2012. <http://amasci.com/amateur/hovercft.html>.
7) "Hovercraft Lift Calculator." Lift System Calculator for Hovercraft. N.p., n.d. Web. 28 Oct. 2012. <http://www.rqriley.com/hc-calc.html>.
8) "Hovercraft." Wikipedia. Wikimedia Foundation, 11 Jan. 2012. Web. 1 Nov. 2012. <http://en.wikipedia.org/wiki/Hovercraft>.