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So You've Always Wanted a Hovercraft... (Video) 66

Posted by Roblimo
from the it's-all-about-the-air-cushion dept.
What little boy or girl never wanted a hovercraft? Something loud that could travel over water, pavement, maybe even over a plowed field or through a swamp? Ben King obviously wanted one, so after he grew up and got his PhD in physics and found a good job, he founded Lone Star Hovercraft. Timothy Lord interviewed Ben at the Austin Mini Maker Faire, and we also found some video of Ben flying (is that the right word?) one of his hovercraft on a lake that we spliced into the interview to liven it up a little. Vroom!

Ben: My name is Ben King. I’ve got a small company called Lone Star Hovercraft, and this is one of our prototypes we’ve been recently developing. It is built using what you will probably call pretty conventional construction techniques. It is just a thin layer of fiberglass on a foam core. So it is very light weight and very strong. The hovercraft itself the whole weighs about 150 lbs. And the engine about doubles that; it is about 300 lbs., ready to fly. So it is very strong, but very light weight. We are working on a few projects. We do some that are conventionally built; we are also working on some projects that are designed to be more like a quick build kit. Because these take anywhere from six months to even a couple of years to build. There are people who want to be on the water, and want to fly but don’t have quite that much time to build from scratch. So we are looking at both conventional hovercraft and also more of a kit type hovercraft just like quick assembly.

Tim: Now if this will take so many months to build, how long can it take to learn those techniques? This is your first one, is it your fifth one?

Ben: This is the third full-size hovercraft I built. I started with plans from a couple of companies, and they really spell out all the processes you use, all the materials so it is a good way to learn – building from plans. And I started even before that doing radio controlled hovercrafts, so everything from electric motors using radio controlled airplane parts up to engines on the leaf blowers and weed whackers and things like that.

Tim: How about that? You’ve got an engine back here. What kind of an engine is this?

Ben: This is a Generac brand engine it is 40 hp. It is a 1 liter V twin off of a basically it is the largest consumer grade generator you can get. And you could also source these engines relatively cheaply and they are very quiet, very reliable. And it is a really good power plant for a hovercraft this size.

Tim: Now you mentioned the idea of making kits. And you’ve got a model over here. Can you talk about modeling?

Ben: Sure, so this is a ½ scale mockup of a kit that I am working on. It is made entirely from a CNC router cut plywood. And the idea is it goes together much like a IKEA furniture, so it all slots and grooves. And there is really minimal measuring, minimal cutting - you basically will get the kit and put it together and hopefully, customize it to make it your own, with your own power plant, your own paint things like that. But the idea is to take a lot of the grueling work out of the process, and get you the fun part faster.

Tim: So what would people need to add if they bought a kit to make a hovercraft like this? What parts would you include and what parts would someone else need to buy?

Ben: We would try to include most of everything you would need for the full kit. So basically the whole kit, and then probably also the engine is an option, and then a reduction drive that slows the propeller down, propeller and then also the molded ducts so that is the duct in the back there, that will be part of the more or less standard kit. And for customization, you could add whatever kinds of controls you like, whatever kinds of paint jobs you like, things like that.

Tim: Now this boat, how maneuverable is it, compared to a canoe or a row boat?

Ben: It is very maneuverable once you have the knack for it, it takes a little bit of practice, but it is often compared to flying a bar of soap. So you have to look as far ahead as you can when on the water, or wherever you are and look for obstacles coming up, and you have to turn in advance, so it flies like a spaceship or an airboat, you turn and you push in the direction you want to go. And so you don’t have the steering that you are used to in a car or like the brakes where you have instant feedback. You really got to anticipate where you want to go and fly ahead about 10 seconds.

Tim: For propulsion, you have only got the thrust in one direction?

Ben: Right, right.

Tim: How much that of that motor’s 40 hp goes into actually lifting the craft?

Ben: About a third is the general rule of thumb. So about a third is directed beneath the craft and the lift air box that you see in the back. Part of that actually inflates this vinyl skirt, about 10 percent of the air, that’s actually sealed, so the remaining 90 percent goes beneath into the center of the craft, into what’s called the plenum that actually lifts it.

Tim: Is the skirt your own design as well? It is the whole thing?

Ben: It is pretty standard. It is called a bag skirt. So these are pretty standard designs.

Tim: And you described this as a homemade project? Is it literally built in your garage?

Ben: Built in the garage, yep. This is the third one. I’ve got a decent garage now, so I build there. The first one I built in a living room of a third floor apartment, and lowered it out the balcony window.

Tim: You must have a pretty big staff?

Ben: I had some buddies help me out. Yeah. So it is home built so it is built in the garage, and you really can make some pretty cool stuff just in the garage with everyday things you have around the house.

Tim: Now where are you going to actually drive your hovercraft?

Ben: Usually it is licensed as a boat, as you can see, it has got boat tags for the state of Texas. You can ride them pretty much on any reasonably flat surface, so grass, ice, mud. There aren’t a lot of public places you can ride, like on grass, or land. So generally they pick a lot of water. That is the most readily available place to go. So lakes and rivers.

Tim: Was licensing a hard thing to get done?

Ben: Not at all. In Texas, it is really very easy. You license it as a homemade vessel, you basically tell them how much power it has, how much it weighs, and that’s pretty much it.

Tim: And you are here at the Maker Faire, why so?

Ben: Well, I like the general atmosphere, it is really exciting, and also we’ve been doing this for a long time, using really conventional methods, and what I find is it is really exciting to see all the new tools that are becoming available, even just in the last two or three years. So we are already using a CNC router, we use water jet cutting, we are starting to get into 3D printing, so there is a lot of really cool technology here that can be used directly in making hovercraft and vehicles like this. So it is really cool to see what’s cutting edge and what people are doing.

Tim: I know you can’t pin down a price on a product that is not out for a while, but in general, what sort of price comparisons might somebody find in looking at a new hovercraft versus what you hope to do in making the kit?

Ben: We are hoping if you look around for production turnkey hovercraft they start at around $20,000 or a little bit less – it is pretty high for a weekend vehicle. We are hoping to come out with a kit that might be like a third to less than half maybe of that price. But with a little bit of labor, you can have a similar craft that is high performing at a pretty small fraction of the price.

Tim: Speaking of weekend, this isn’t your day job, is it?

Ben: No it is not. It is a side a small business along the side.

Tim: What’s your background and what do you do during daytime you work week?

Ben: So my background is in physics, I got my PhD in physics; I studied fluid dynamics so a lot of it really relates well working on props and engines is really exciting. So I work at an energy company during the day doing research.

Tim: Anything else people should know, if they want to find out more about this?

Ben: I am sorry

Tim: What would people need to know if they want to find out more about this?

Ben: Those who want to find out more, we try and keep our website pretty up to date, so it is www.lonestarhovercraft.com. So we’ve got several build logs that have complete start-to-finish construction pictures, we have a lot of work on engines, videos, things like that. So we try to make it a really useful resource for builders and people wanting to do their own craft. So that is the best source.

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So You've Always Wanted a Hovercraft... (Video)

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  • by XxtraLarGe (551297) on Tuesday May 21, 2013 @02:23PM (#43784457) Journal
    I'm not very fond of eels, and I'm afraid my hovercraft might get full of them.
    • by bizitch (546406)

      My nipples explode with life!

    • by TeknoHog (164938) on Tuesday May 21, 2013 @03:41PM (#43785449) Homepage Journal
      I've had it with these motherfucking eels in this motherfucking hovercraft!
    • by cgimusic (2788705)
      Provided you buy your translation dictionary from a reputable dealer you should be fine.
    • by catchblue22 (1004569) on Tuesday May 21, 2013 @05:02PM (#43786919) Homepage

      When I was a teenager, the father of a wealthy school friend won a hovercraft in a card game. It looked quite similar to the one above. It was powered by a Bombardier snow mobile engine and was extremely loud. It would only hover when the fan was running, as the airstream for the hovering air came from a diverted stream of about 1/3rd of the prop wash air. Steering it felt a lot like trying to push one of those Ikea shopping carts that has four pivoting wheels...during a turn, you end up going sideways for a time. Going over water, it felt not unlike being on a loud boat or a seadoo. Going over land, it felt like being on a loud ground vehicle. The cool part came when we could drive it over a mud flat which alternated between sand and water. It really was an unusual sensation. The problem was that it ate fuel like crazy. It was far worse than a regular boat. The other problem was that when it came to a rest, the sand started to grind down the bottom. We did mitigate this by adding some fiberglass enforced wooden rails. Overall, it was great fun as a teenager, but even if I had the money to dump on such a toy, I doubt I would.

  • by ickleberry (864871) <web@pineapple.vg> on Tuesday May 21, 2013 @02:27PM (#43784493) Homepage
    I have my hoverboard with jets at the side pre-ordered for 2015.
  • by Art Challenor (2621733) on Tuesday May 21, 2013 @02:41PM (#43784697)
    I miss the hovercrafts that used to cross the English Channel. Very cool machines that would make you throw up in anything but the calmest seas - http://www.youtube.com/watch?v=A02u03xhpPw [youtube.com] . Victims of the EuroStar and other circumstances. You want fast, you go by train, you want low-cost, you go by ferry.
    • You want fast, you use a teleporter. You want low-cost, you stay home.

  • by kraut (2788) on Tuesday May 21, 2013 @02:47PM (#43784753)

    Although I have to say that the downside is that these are going to be just as annoying as jetskis, but in places where jetskis can't go.

    The other day I had two share a beautiful, quiet, peaceful woodland with two irritating idiots on noisy little dirtbags. not nice.

  • by SoCalChris (573049) on Tuesday May 21, 2013 @02:57PM (#43784893) Journal

    The word that you're looking for is hovering. As in "hovercraft".

    • The word that you're looking for is hovering. As in "hovercraft".

      This isn't flying, this is falling with style!

    • No, flying isn't the correct word.

      Story I heard, back in the '60s. (Don't know if it's true, unfortunately. But I think we have some Ann Arborites here who might check the city ordinances.)

      Plans had been published for making homemade hovercraft with a salvaged lawnmower engine. Stand on it like a Segway and steer by leaning.

      Kid had made one and decided to take it down the LOOOONG, somewhat steep, slope of Hill street one night. (I shiver at the thought of how fast that would be going near the bottom...)

    • by ketomax (2859503)
      I prefer witching in a witchcraft
  • by 0123456 (636235) on Tuesday May 21, 2013 @03:07PM (#43785001)

    When I was at school about twenty years ago some of the kids built a similar-sized hovercraft as a project and used to ride it around the playground. Given how cheap our school was, it can't have cost them much other than a second-hand engine and some wood for the body and fins and rubber for the skirt.

    Recently I read an old Arthur C Clarke article from the 50s or 60s about how hovercraft were to be the future of transport and no-one would want wheels any more. I guess it just wasn't this particular future.

    • by Rob the Bold (788862) on Tuesday May 21, 2013 @03:42PM (#43785467)

      Recently I read an old Arthur C Clarke article from the 50s or 60s about how hovercraft were to be the future of transport and no-one would want wheels any more. I guess it just wasn't this particular future.

      I always wanted a hovercraft in the future, but I was too lazy to learn Esperanto.

    • by Solandri (704621) on Tuesday May 21, 2013 @05:31PM (#43787325)
      Their problem is (1) active suspension, and (2) lack of directional stability.

      (1) If your car is stopped at a red light and its hybrid engine shuts off, you're burning no energy. A hovercraft stopped at a red light is still burning energy to maintain the air cushion. Same thing is true at speed - the car's suspension keeps the chassis off the ground at (close to) zero energy cost. A hovercraft is always burning energy to stay off the ground.

      (2) When you drive a car on a road, the wheels are physically locked (up to the coefficient of static friction) with the road. You have to exert a significant amount of torque to the car before the wheels unlock from the road and the car starts to spin/skid. So a car is pointed in the direction it's traveling nearly all the time. This reduces directional control to a simple one degree of freedom problem - the more you turn the steering wheel, the faster you change direction.

      With a hovercraft, the slightest torque on it will change its orientation. Even an airplane does better - its high forward velocity generates a stabilizing aerodynamic force on the tail to keep it pointed somewhat in the direction of travel. OTOH, a hovercraft's slower forward velocity means it needs to rely on vectored thrust for orientation stability. So now you've got a direction of desired travel which is mostly uncoupled from the direction the hovercraft is pointing (yaw). And if you do get turned away from the direction you're traveling, a righting moment to yaw it in the right direction again will also impart a small translation, thus changing your direction of travel slightly.

      It's actually more akin to piloting a spacecraft in 2D than it is driving a car. You can do tricks like spinning 360 degrees without changing your direction of travel (much). Which is fun in theory, and perhaps useful if you're in combat. But it's added complexity which makes piloting one more dangerous that driving a car for the average layperson.

      Also, the advantage that it can travel over water is a bit of a misnomer. At low velocities, a hovercraft on water acts pretty much the same as a displacement hull. The air cushion sinks down until it's displacing the hovercraft's weight in water. Moving forward then involves pushing the hovercraft uphill over the front lip of the depression in the water it creates, just like a displacement hull. You're only slightly better off than if you were in an amphibious car. As you pick up speed, the wave resistance begins to decrease. The tradeoff point where it becomes more efficient than a planing hull varies with size, but it's typically around 30-50 knots, which is why they haven't displaced planing boats as the recreational watercraft of choice - there's little to no advantage at these speeds. For it to be nearly as efficient as traveling on a solid surface, you have to be moving at close to 100 knots over the water.
      • You mentioned hovercraft combat.

        One time I was being chased by this maniac in a hovercraft. He even ran me over on the beach. I got some sand in my mouth, but I was unharmed. He chased me all through town. Eventually I grabbed a sword from an antiques shop and commandeered a Lamborghini. Playing chicken with the hovercraft, I swerved at the last moment and was able to slice up its tender bits. So hovercrafts are quite vulnerable to swords. I still was pretty lucky though.

    • by iggymanz (596061)

      good reason they aren't more popular in the one to four person size range, they get horrible fuel economy. My two friends get 4 to 6 miles per gallon on water with theirs. funny the claims the vendors make of them using half the fuel of a boat, the hovercraft is carrying only people but a boat will be able to have cargo too.

  • I'd prefer the Dark Helmet model.

  • by YrWrstNtmr (564987) on Tuesday May 21, 2013 @05:01PM (#43786913)
    Plans for these have been around forever. Many, many people have built them.
    hovercraft.com [hovercraft.com] has many plans and kits for sale.

    When my son was 9, he called me at work one day. "Dad, do we have a leaf blower?"....Yes..."Do we have a piece of plywood 4 feet wide?"....Yes. (I can see the wheels turning)...He goes on to list a bunch of other parts.
    'Ok, dude....why?'
    "I have a science project! I want to make a hovercraft!"

    "OK then." He had gone online and found plans for a simple floating platform. No forward thrust, powered by a leaf blower.

    It worked well enough to float my fatass down the driveway.

    He got an A. My wife freaked out when I chose this as a teaching moment in how to use a circular saw.
  • ... did the first hovercraft crossing of the Cook Strait in a home-built hovercraft. He then checked out the ferry times for the return trip home, checked his watch, and shortly after did the second hovercraft crossing of the Cook Strait in a home-built hovercraft.
  • Homemade hovercraft used to be a big thing since at least the '50s or '60s (and for all I know still are). Typically made by putting a prop on a vertical-axle lawnmower engine and building a simple vehicle body with a fan shroud in the middle.

    There was a classic disaster that happened to a LOT of people who did this:

    After they'd played around on land with it for a while they'd decide to test how it would perform on water. So they'd take it down to the local park-on-a-lake, fire it up, and drive out onto t

  • Why hovercraft never caught on:

    Expectation: http://www.google.com/search?q=concept+hovercraft [google.com]

    Reality: http://images.google.com/search?q=hovercraft [google.com]

    Perform this search experiment with Hoverbike/Concept Hoverbike as your search term and the disparity is worse - the real world things, even the expensive ones always look like they've been made in some back yard.

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