So…circa ~2000 two friends and I built a hovercraft. I’m resurrecting those photos because it was such a cool project. Why build a hovercraft? As Daryl put it, we wanted to see if those ads in the back of Popular Mechanics were real. And we were young with a lot of free time.
Here is a summary of the construction process that went into building this hovercraft.
What would we build, who would be involved, where would the hovercraft be built, what kind of tools were available, what tools would need to be acquired, what would be the cost, how long would it take to build.
Buy the hovercraft blueprint, buy materials, buy equipment, set up the construction area.
- Frame Construction
Construct the wire frame of the hovercraft.
- Hull Construction part 1 of 2
Create the sides and bottom of the hovercraft.
- Lift Duct Construction
Create the lift duct cavity.
- Thrust Duct Construction
Create a thrust duct frame.
- Propeller Construction
Fabricate a lift propeller and a thrust propeller.
Coat the hovercraft in fiberglass.
- Lift motor mechanics
Acquire a lift motor, mount a propeller onto the motor then mount that to the lift duct.
- Thrust motor mechanics
Acquire a thrust motor, mount a propeller onto the motor then mount that to the rear of the hovercraft.
- Operational mechanics
Create mechanics to operate engines and steering.
- Steering mechanism
Create foam fiberglass fins to steer the hovercraft.
- Cockpit assembly
Create a place for a driver and passenger to sit as well a create mechanics needed to operate the hovercraft.
- Skirt construction
Create a skirt from rubber and attach the skirt to the hovercraft.
Add inflatable plastic containers to the hull of the hovercraft for floatation.
- Hull Construction part 2 of 2
Create the top of the hovercraft and walls of the cockpit.
- Testing and water proofing
Test the hovercraft and implement water proofing to allow the electronics to operate in salt water conditions.
- Trailer construction
Create a trailer that will transport the hovercraft and add any necessary lighting/turn signals.
Paint the trailer and hovercraft.
- DMV visits
Work with the DMV to license the trailer for use on the streets and license the hovercraft as an amphibious vehicle.
Every hour of operation required about 3 hours of repairs. Most repairs went towards patching the lift skirt and fixing dents in the propellers.
That sums up the major categories of effort that went into construction of this hovercraft. The entire process did not have any major hang ups. At first it was frustrating to come across situations that were not explicitly explained in the blueprints. Over time it became more comfortable to improvise.
Obscure observations that came up while building the hovercraft.
- The lift duct was particularly difficult because precision was important. The tips of the lift duct propellers needed to clear the lift duct by a few millimeters. To do this the lift duct had to be a near perfect circle. The lift duct started as a piece of ply wood, two feed wide, that was bent to form a circular tube. Making that tube a near perfect circle required a lot of trial and error. The lift propeller spun at a high RPM so any contact between the propeller and lift duct would have been catastrophic.
- Faith in the blueprints solved many problems. The propellers were a good example of this. Making propellers out of wood blocks did not make much sense at first but the directions were good enough to overcome my doubts.
- Deviating from the blueprints was ok. Situations did arise where the blueprints did not have answers and it was ok to create our own solutions.
- Bigger is better. The engines used in this hovercraft were near the top of the allowable limits. Were I to do this again then I would have tried to use the biggest engines possible.
- Lastly, building the hovercraft was more fun than driving the hovercraft. It’s a douche thing to say the journey is more important than the destination, particularly if it is said to calm someone that is frustrated, but it’s true. Once the hovercraft was built we could take it out at will but we could never go back and rebuild it. Building it was a experience that we couldn’t relive even if we wanted to.
Observations that came up while driving the hovercraft.
- It is like driving a car on ice.
- It is very noisy.
- It is very dirty.
- Water can be treated like solid ground.
- You must anticipate any change in motion, turning or stopping well in advance.
- The use of hovercrafts in public is a gray issue where Park Rangers don’t mind and others mind a lot.
Finally, here are some log entries for those times where the hovercraft was taken out.
|San Marcos High School||Very first trial and the thing worked. We were running out of daylight and needed someplace to test out both engines simultaneously so we set up in the parking lot of the high school across the street. We did not have a throttle for the thrust yet so one person steered while the other pulled the bicycle cable that controlled the thrust engine. We were all shocked to see it hover and accelerate for the first time. It moved over speed bumps and those cement blocks in front of parking spaces like they were not even there. We also decided that braking is definitely a very significant issue so engine cutoff switches will be needed. We kicked up a lot of gravel and dirt. Dirt gets everywhere, inside the craft your hair, ears, everywhere. The key here is to find surfaces that do not have as much gravel.|
|Storke Field||The Santa Barbara Newspress came out to do an article. UCSB was on spring break so we decided to try out Stork Field by Harder Stadium. The craft moved sluggishly on grass. On grass air may be leaking through the blades of grass. We all took turns, including Rupert, Daryl, the reporter, cameraman, and myself. The article can be found here, Page 1 and Page 2.|
|Storke Field||Telemundo Channel 47 contacted us on doing an article for their news channel. We went out to Storke Field again. The guy on the tractor cutting the field was nice enough to stand by for a few minutes. The hovercraft moves at maybe 25mph on this grass. The news segment appeared on TV in Spanish, I need to digitize it or get a translator. The camera man didn’t speak English very well but that was cool because driving the hovercraft is pretty simple when there’s nothing to run into.|
|Lake Cachuma||We arrived at Lake Cachuma on April Fools day of all days and were not let in the park. That day we were told that the craft “had to be certified by the Coast Guard to enter the park.” So the parks people cried about Lake Cachuma being unsafe if people touch the water. But the craft does have a CF number and HIN(kinda like a VIN for your car) from the DMV. I went through the laws put up by the Coast Guard and confirmed over many phone calls that our hovercraft does meet all boating regulations. What could be safer for a lake then something that does floats on water? So Lake Cachuma would not let us on the reservoir because the bass fisherman were jealous that they didn’t have such a cool boat. Actually County Parks rule 2687c states something like to operate on a lake the craft must be determined to be of standard design as determined by the director or a deputy for canoes, kayaks, rafts, and/or inflatables. In a nut shell anybody dressed up in a funny hat can do whatever they want. We all disagree with this. So we took off to Storke Field again. Jeremy, Daryl & I set up a slalom course – no problem at low speeds. Then we decided to try it for the first time at the beach. We launched at Goleta Beach and everything looked great. But as we got close the salt water, the engines cut out. Salt water is more conductive than fresh water and we now know that the salt water shorted out the electrical system in both engines.|
|Goleta Beach||We tested the engine by dousing it with water then spraying the engines with salt water. So we went off to the beach with high hopes. We encountered the same problems with salt water as the day before. However the problems were less severe as we encapsulated the spark plugs in thicker rubber boots. It was a bit embarrassing to draw a crowd then get it stuck in water and take 10 minutes yanking cords to restart the engines.|
|Goleta Beach||The craft now works fine over salt water. We insulated all electrical contacts with silicon gel. It was a bit nerve racking to see it hover for the first time over the ocean but it never cut out. I learned how not to maneuver the craft by trying to drive through an inlet and running into the cliff. A hole was punctured into the bottom of the craft. It is now repaired to where that part of the hull is a bit stronger. We let some random UCSB engineering student try it out then Daryl took out a guy with his 9-year old son. He then emailed Daryl to say that his 9-year old son has been putting lego hovercrafts together ever since that day.|
|Goleta Beach||Had a nice day at the beach for a few hours. We gave rides to a lot of friends in the Henchmyn band. Unfortunately some student drivers got a little too close to the beach goers and a county parks guy was there to tell us to take the hovercraft home. That and Daryl scaring several hundred birds in the air ruined our welcome. It is pretty amazing every time the hovercraft goes from land to water – almost like watching someone walk on water.|
|Goleta Beach||KEYT Channel 3 came out to film us at the beach. We got it running on a foggy day with low tide. It runs very fast on wet sand. Daryl was driving pretty fast along the wet sand and thought he could make it between the columns of the Goleta Pier. Well it was great for the camera up to the point where Daryl decided that wasn’t a good idea and turned around. But the craft was moving too fast and did not slow down in time before bumping into the pier. And once again the County Parks guy was there to advise us to get insurance before returning. The incident with the pier scratched up the lift prop and the lift engine mount. The lesson here is to be more careful when on smooth surfaces.|