Thursday, October 30, 2008

We can't get there from here

In an earlier post, I talked about the proposed new replacement for the Tappan Zee Bridge in New York, and the high costs of just that one bridge.

In an article from eight years ago in the NY Times, author David W. Chen talked about the plans back then for replacing the bridge. He also made these general points about trying to increase capacity for highways or bridges:
Not so many years ago, it was common wisdom that the only way to relieve highway congestion was to add new lanes. Now the common wisdom, supported by several recent studies, is that expanding a road usually leads to substantial increases in the number of vehicles on it. ''Adding highway capacity to solve traffic congestion is like buying larger pants to deal with your weight problem,'' said Michael Replogle, transportation director of the advocacy group Environmental Defense, in Washington.

So in New Jersey, the state transportation commissioner, James Weinstein, could go before a business group last week and utter words that would have been heresy in that car-besotted state just a few years ago: ''We're past the period where adding lanes is the solution to traffic congestion, make no mistake about that.''
And, that of course, is why the current wheel based ground transportation system is at maximum capacity, a capacity that cannot be increased, and a capacity that will require enormous expenditures just to stay at the same level. In other words, cars and trucks on roads will overall become bottlenecks as the USA (and world) population continue to increase, slowing down the economic and social progress of society, and yet still requiring huge sums of money to keep infrastructures usable.

For this reason alone - and there are numerous others - we can't seriously consider today's transportation system as belonging to the future. Unless it is replaced by something much more flexible and far less expensive, our future will be all the less desirable. Those who have been reading these blog entries know that my company, Aeromobile Inc., has developed a ground transportation system consisting of air cushion vehicles in elevated guideways. We call it the Aeroduct System, and its many advantages are given on our website and in earlier blog posts. For the purpose of today's blog, the advantage I want to promote is how it will allow capacity for travel along the surface or across rivers to greatly increase. There will be no bottlenecks, and congestion will become something of the past.

The Aeroduct guideways will be much lighter than paved roads and much cheaper to build. And they will be orders of magnitude lighter and cheaper than elevated pavement, including bridges. The guideways can be stacked vertically or horizontally, allow infinite expansion of capcacity as needed. Automation of the air cushion vehicles in the guideways will allow faster speeds than cars and more consistency in vehicle movement. Even one aeroduct guideway will allow more throughput than a road of today, and it will be much simpler and cheaper to add guideways when the demand is there. And, aeroducts will carry vehicles of any size, so air cushion trucks as well as air cushion cars will be used.

If we stick with cars, trucks, paved roads, expensive and woefully overloaded bridges, we won't get to any sort of promising future. We'll be stuck in the traffic of a now obsolete technology, and spending all our money for that dubious privilege. With the Aeroduct System, we have the technology enjoy a liberating means of travel instead of a continuing to suffer from an increasingly constrictive one. I invite anyone with any interest in a better future to let me know what he or she thinks.

Thursday, October 23, 2008

Going in the Right Direction

The cover of the November, 2008 Popular Science magazine features a proposed design for an four passenger tilt wing vertical take off and landing (VTOL) aircraft. The design has unique features, including the use of an electric/piston engine hybrid power system, which leads to a lightweight craft. The story can also be seen on the Popular Science website.

I applaud all attempts to create vertical take off and landing airplanes for trying to take general aviation in the right direction. Airplanes should take and and land in the minimum amount of space, and runways and airports should be only for the really large jets. However, I do have some issues with this design by a British company called Falx. Many of these remarks are similar to those I made about the V-22 Osprey in other blog entries.

  • I believe that tilt wing (and tilt rotor) have a design flaw in that one of the propellers can get caught in its own turbulence as is comes in for a landing. This is known as vortex ring state.
  • The laterally disposed rotors present an asymmetrical lift situation, and any unequal lift from one or the other propellers can cause severe roll moments. It is essential to have centerline thrust
  • In total power failure or “running out of gas“, a tilt wing aircraft is a free falling body. It cannot use its wing for gliding flight to non disastrous landing, because the large propellers will impact the ground on landing and crash the craft. Again, neither can it autorotate its propellers like a helicopter, allowing a hard but survivable landing.
  • I believe the Falx tilt wing machine is grossly under-powered. A four place helicopter can lift 4 passengers with 150 h.p., because of it 40 foot diameter rotor. Thrust efficiency of rotors is directly proportional to the swept area of the rotors or propellers. To lift four people with two puny single rotating propellers of the tilt wing will require more than 1000 h.p. It is inconceivable that batteries and the proposed 104 HP engine can muster that power and be light enough to fly horizontally, long take off, much less vertically, or VTOL.
I'm not saying any of this to deter the Falx people or any other aviation inventors. I think it is good that others are pursuing the "Holy Grail" of general aviation, which is adding vertical flight to a fixed wing aircraft. I have spent many years - 55 of them in fact - exploring VTOL technology, and I really do think that the elements of my Arc Wing VTOL airplane are important to the proper design of any aircraft that will take off and land vertically. These elements include center line thrust, large dual-rotating propellers, the deflected slipstream approach to vertical flight, and the Arc Wing, which has unique lift. More about this craft can bee seen at our website and other blog entries.

In the 1940s and 50s, a lot of government sponsored research was performed on all sorts of approaches to vertical flight. In those pre space race days, innovation in aviation, including VTOL, received a lot of attention and funding. Many of the VTOL designs of those days had issues that limited their effectiveness, and others petered out when aviation funding was greatly decreased. Those extent of the approaches to VTOL can be seen in Micheal Hirschberg's exceptionally comprehensive VTOL wheel of misfortune.

Thursday, October 9, 2008

Bridging the Gap

On September 26th, the New York State Department of Transportation issued a press release which announced "PROPOSAL FOR TAPPAN ZEE BRIDGE & I-287 CORRIDOR UNVEILED Team Recommends Bridge Replacement, Addition of Bus Rapid Transit & Commuter Rail."

Tappan Zee Bridge is located about twenty five miles north of New York City, and is almost three miles long, including approach ramps. It was built in the early 1950s, is very heavily used, and the New York State Department of Transportation must do something about either extensively refurbishing it or replacing it. The press release indicates that remodeling it is not a viable option:
The Tappan Zee Bridge, constructed 52 years ago, was built according to prevailing standards in the early 1950s. While the bridge is safe, its design does not meet current national standards for structural elements and some of its deficiencies can not be addressed – even in the most robust rehabilitation scenarios – because of the structure’s basic design characteristics.
The replacement plan (or plans, since there are several options) and cost(s) are as follows:
Full implementation of the project team’s proposal would cost: $6.4 billion for a new bridge accepting bus rapid transit and commuter rail transit; $2.9 billion for bus rapid transit and highway improvements; and $6.7 billion for the build-out of commuter rail transit in the future.
The Tappan Zee Bridge proposal is notable for certain reasons:

1) It will cost a great deal of money, especially with the options for including rapid buses and a rail line. Because it spans one of the widest points of the Hudson River, it is a long bridge, requires many supports and therefore more preventive and actual maintenance.

2) The project reinforces the idea of transportation corridors. For cars or trucks to traverse the Hudson, they must all converge on the area of the bridge. There is no bridge within twenty miles north or south of this one. The mass transit additions of lanes for rapid buses and commuter trains further accentuates the bridge as being an important transportation artery; in other words, confining transportation to a corridor.

Considering the great cost of any new bridge, the focus on making this one even more of a transportation artery by adding mass transit capacity isn't surprising. On the one hand, we can look at this as confining travel to across the Hudson to just one structure for over 50 miles. But, to broaden the transportation corridor by building another bridge perhaps 10 miles to the south or to the north would not only require great expenditures of money on this other bridge, but would require new roads to take people to the bridge, adding even more expense.

Every place where transportation requires bridges endures bottlenecks and safety issues beyond those of just roads. Bridge costs for creation and maintenance are very high. As I've said in earlier posts, bridges are hammered day and night by heavy cars and even heavier trucks. And, adding special lanes for fast buses or trains will increase the load on the bridge, requiring more support, more maintenance and more expense. Certainly the mass transit additions to the bridge decrease dependence on cars, but they still add to the pounding the bridge must endure.

Our Aeroduct System will also need to cross rivers, but will require much less support and will endure far, far less pounding from the vehicles in the system. The pressure exerted by air cushion vehicles on their guideways (or "roads") is very light. An Aeroduct bridge would require some supports for longer spans, like that bridged at Tappan Zee, but these supports would be fewer and more lightweight. So, more crossings of the Hudson or other bodies of water could be built, all for much less money, putting an end to clogged transportation arteries. And, the guideways can be stacked horizontally or vertically, allowing far more throughput than current bridges.

It should be clear that any attempts to "upgrade" existing infrastructure for wheel based infrastructure will be hugely expensive and do little to decrease the congestion and high maintenance made necessary by the nature of that infrastructure. The Aeroduct System will cost money to implement, but it has far more potential than the roads and bridges of today, and will be vastly cheaper to build or maintain, will be safer, weather immune, faster and extensible. Faced with what will be a trillion dollar budget to just keep our existing roads and bridges from falling apart, and that is without adding any new capacity, shouldn't we be looking for an alternative?

Here is a color sketch of an Aeroduct "tube" crossing a river. As you can see, it uses open guideways leading up to the bridge, and then a closed tube across the water. A complete tube has inherent built in support, ideal for a span. If the river were wider than shown below, supports anchored on the river bed would also be needed.

From my perspective, we can continue to spend all sorts of money on keeping alive a transportation system that has many drawbacks, or we can spend our money building an entirely new system with many advantages. To find out more, here are links the Aeroduct System website and to other blog entries.