Freeing Up Runways

Pierre Sparaco discusses the lack of runways at major European airports in his article "Runways Are Forever" in the Aviation Week & Space Technology journal of February 2, 2009. Due to cost and environmental concerns, airports in the UK, Germany and elsewhere have moved very slowly to add new runways, leaving the existing ones too crowded today and even more crowded in the future.

The larger commercial airplanes of the future - the Airbus A380 and the larger Boeing craft - will need long runways. They and their somewhat smaller Airbus and Boeing bretheren are long take off and landing aircraft, and such aircraft are the best way to tranport large numbers of air passengers long distances. But, much of the air traffic today consists of smaller airplanes, which still need runways, and therefore compete with the large jets for runway space. These craft, which usually travel less than 1000 miles (1600 km), could and should be replaced by VTOL airplanes. Our Arc Wing VTOL airplane can be scaled up to replace "regional" jets and air taxi services. VTOL craft would not need to use runways at all, allowing the existing ones to be dedicated for large jets.

And, the issue is not just with adding new runways. In some regions - New York, for example - new aiports have been proposed, to alleviate the crowded runways at existing airports. With VTOL regional airplanes and VTOL taxis, new airports will not be as necessary. And, the financial and environmental disagreements over adding a new runway are quite tame with the opposition generated over an entirely new aiport. It would make much more sense to make the best possible use of the runways we have, leaving them for just the large jets. Let's develop VTOL technology. It has so many advantages, and reducing runway overuse is among them.

A Better Shuttle - Part I

In the USA Today of January 15th, an article by Larry Copeland called "Forget the Cab, Take a Shuttle Flight", explains how a new air shuttle service is being offered between Gwinnett County airport and Atlanta's Hartsfield airport, 43 miles away. All this so that residents of Atlanta's suburbs do not have to risk missing a flight at Hartsfield due to the often unpredictable traffic slowdowns encountered when driving a car to the airport. I hope the service is successful. But, I'd like to talk about how two of the technologies I've worked on might make the service even better.

In Part I of this blog entry, I'll relate how the Arc Wing VTOL airplane would be the best possible shuttle to get from anywhere to Hartsfield or any other large airport. In Part II, I'll discuss how we can eliminate the traffic congestion that is the problem in the first place.

A VTOL airplane is the best possible way to get people by air from one place to another. The Arc Wing VTOL airplane which I've been working on for many years would let a shuttle service takeoff just about anywhere in the Atlanta area, without any airport being necessary, and land at Hartsfield on a vertipad (a variation of a helipad), allowing the runways to be dedicated to large aircraft, like airliners. This would be far more flexible than requiring a LTOL (long takeoff and landing airplane) at the starting point, which must be a runway, then a short flight to another airport, where one of the runways must accommodate the smaller airplane along with commercial jets.

The shuttle service would have infinitely more starting points, and make far less demand on the runways at Hartsfield, the destination point. A company using the Arc Wing VTOL airplane for its shuttle fleet could have many starting points at various distances from Hartsfield, and truly accommodate all those who want to get to the large airport without having to deal with stupefying automobile traffic.

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.

Civilian Tilt Rotor Baggage

The Bell/Agusta BA609 civil tiltrotor has been in the works for a over 10 years, as reported by an August, 2007 article in Aviation International News (AIN) called "As time passes, operators question BA609 appeal". That article goes on to relate the diminishing interest by potential buyers of the craft. A more recent article in 2008 by Aero News Net, titled "BA609 Tiltrotor Makes Its First Appearance At Show", further confirms this by saying "but officials at the American helicopter manufacturer [Bell] have recently signalled the market they once saw for the aircraft has declined significantly in today's economic conditions."

From our perspective, an airplane that can take off and land vertically like a helicopter and also fly as fast and with the same ease as a fixed wing aircraft is the ideal. So, why are people losing interest in the BA609? The primary reason is cost: almost $20,000,000 for a plane that carries eight or nine passengers. With that kind of money, one could buy several helicopters or about five very light jets (VLJs). Other issues quoted by the AIN article are: that the craft is "too big for use on standard helipads and yet too small for comfortable executive charter." Given the already existing helipads in major cities, oil rigs, company campuses, hospitals and private homes, an vertical flight airplane must be able to use them, or it will require an set of such landing pads of its own.

We've already talked before about the inherent weaknesses of a tilt rotor design. That technology is not the most efficient and most reliable way to add vertical flight capability to an airplane. The lack of efficiency and the potential safety problems is what has swollen the cost of the BA609 to far more than any of the competing aviation modes: helicopter or fixed wing plane. We think it just is not possible to build a tilt rotor vertical take off and landing (VTOL) craft without spending money on redundant computer systems and other complexities, thereby inflating the cost considerably.

We do offer an alternative: our Arc Wing VTOL airplane. By using deflected slipstream technology, which we think is the most efficient (the most elegant, really) approach to vertical flight, our craft will cost about the same as a VLJ and will be far more inherently safe than a tilt rotor craft (or even helicopters) due to the simplicity and aerodynamic qualities of the design. We invited all those interested in the best possible VTOL airplane to look into our proposal. The Arc Wing VTOL can be scaled from four passengers to far more. The smaller ones will easily work with existing helipads. The larger craft will have to be accommodated as per their size. In all cases, the cost will be similar to turbine fixed wing planes of corresponding size.

Safety in the Snow

In April of 2008, the NY Times published an article called The Last Frontier of Flying by writer Weld Royal. It relates the great need for flying general aviation (GA) craft as the only means for travel for most of the state of Alaska. But the article points out how dangerous flying can be in the 49th state. There are few official airports in Alaska, and weather can be volatile. The article quotes the National Institute for Occupational Safety and Health as saying pilots in "the state died at a rate nearly 100 times the mortality rate for all American workers, and over five times the rate for pilots nationwide."

Most general aviation accidents occur at takeoff or landing. In a places such as Alaska, where even small airports are not common, the need that GA aircraft have for long stretches of smooth surface for takeoff and landing work against safe flying. We feel this is yet another reason to develop an aircraft with vertical flight capabilities. As readers of this blog know by now, we happen to have such a craft, our Arc Wing VTOL airplane. It can take off and land just about anywhere, needing a smooth surface only the size of a helipad. This kind of GA aircraft would be the safest possible way to fly around Alaska, or any other place

Here are more blog entries on our vertical flight craft.

Grow the Market

A few days ago, the well respected general aviation (GA) manufacturer, Mooney Airplane Company of Kerrville, Texas USA, announced layoffs and reductions in output out their aircraft. Mooney has long been known for the performance and reliability of their piston aircraft. But, with all piston-engine aircraft sales recently slowing by 28 percent in the USA market, Mooney has had to retrench.

Of course, we wish Mooney the best in the future, as we do all general aviation companies. But, we think they'd be much better off looking into the arena of vertical take off aircraft in order to grow the market. Conventional GA fixed wing aircraft, no matter how well built and no matter how stylish are going to be a limited market: for travel from one airport to another. What people really want is to travel from where they are to to their precise destination. Vertical flight airplanes give the flexibility of much more convenient take off and landing locations, and the fast speed and flight smoothness of fixed wing aircraft.

We invite Mooney and all other GA manufacturers to look at our design for a vertical airplane. We call it the Arc Wing VTOL airplane, due to the unique arc shape of the wing. We've posted a number of blogs entries on this design. And, our website gives much more information, including documents presented to aviation conferences, and videos. We feel our aircraft will broaden the appeal of general aviation, and that can only help everyone involved with it.

Arc Wing Versus Planar Wing

In the June 2008 edition of Flying Magazine, noted aviation expert and writer Peter Garrison writes about the forces associated with airplane lift in a very interesting article titled "The Bernouilli Brigade". He discusses at length why the lift possible from a wing is less than one would think. Here is some of what he says:

"The pressure difference between upper and lower surfaces causes spillage at the tips - this is the reason for the tip vortex - and robs the wing of 5 to 10 percent of its theoretical lift. Another loss occurs at the center of the wing where the fuselage interrupts air flow. The imaginary portion of the wing that lies within the - reported wing area includes this hidden part - produces in reality, no lift. But changes in the pressure are gradual, not instantaneous, and so the effect of the fuselage is to produce a dip rather than a sharp-edged gap in the spanwise distribution of lift. Depending on the fraction of the wing that lies within the fuselage, another 10 or 15 percent of potential lift may be lost here."

He also refers to the losses from the tips of the non-spanwise flaps.

His article deals with the loss of lift of the straight or planar wing. At Aeromobile Inc., we think our arc wing obviates several of these losses. In my previous blog entry, called "A Wing that Really Lifts", I list all the reasons the arc wing has superior lift to the planar wing. Here I will just mention a few:

1. The arc wing has inherent "winglets" and minimal tip vortices to reduce that 5 to 10 percent of lift of the straight wing.
2. There is no fuselage interrupting the arc wing span. The fuselage is under the arc wing saving a additional 10 or 15 percent of wing lift.
3. Taken together, the theoretical saving of the arc wing over the straight wing without the fuselage interrupting may be as much as 10 to 25 percent.

A Wing That Really Lifts

I've talked about the Arc Wing VTOL airplane in a number of earlier posts. Today, I want to talk mostly just about the arc wing itself. No airplane today has a wing like it, and I feel it would have many advantages even for conventional take off and landing (CTOL) aircraft, as well as vertical take off and landing (VTOL) aircraft.

This photo shows just the shape of the arc wing:

And, this image shows the arc wing in combination with a dual rotating propeller and a flap at the back that would be used for VTOL operations:

What are its advantages of the arc wing? When combined with dual rotating propellers:

1. The arc wing has inherent "winglets" and minimal tip vortices to reduce 5 to 10 percent of lift of the straight wing.
2. There is no fuselage interrupting the arc wingspan. The fuselage is under the arc wing saving an additional 10 or 15 percent of wing lift.
3. Taken together, the theoretical saving of the arc wing over the straight wing without the fuselage interrupting may be as much as 10 to 25 percent.
4. The arc wing has greater lift, (L/D), for a given span than a straight wing.
5. An airplane designed with the arc wing will have as shorter span for a given load factor.
6. The arc wing stalls at 33 degrees angle of attack vs. the straight wing that stalls at 17 degrees, resulting in later stall and higher lift.
7. Arc wing flaps are full span and without tip losses, inboard or outboard.
   The arc wing has positive pitch stability that removes the need for a horizontal empennage and the structural weight and drag thereof.
8. The arc wing can assume any angle of attack and "freeze" at any angle of attack by moving the tip mounts fore and aft. We have a video that my son William D. Bertelsen narrates that shows the arc wing stability at any attack angle.