Category Archives: Transportation

The Huge Scale of the Latest Generation of Wind Turbines is Challenging Available Manufacturing and Transportation Infrastructure

In an effort to improve the generating and economic performance of wind turbines, manufacturers have been designing and building increasingly larger machines.  Practical limits on transporting these very long and heavy components between the factories and the installation sites may limit the scale of the wind turbines selected for some applications and may require novel solutions that affect component design, factory siting and choice of transportation mode.  In this post, we’ll take a look at these issues.

1. The latest generation of wind turbines

1.1 GE Cypress platform

On 13 March 2019, General Electric (GE) Renewable Energy announced that its largest onshore wind turbine prototype, named Cypress, started commercial operation in the Netherlands.  Unlike other large wind turbines, the prototype Cypress composite turbine blades come in two pieces and are assembled on site. Cypress was announced in September 2017 and construction of the prototype began in 2018.

The 5.3 MW Cypress prototype wind turbine. Source:  GE

The Cypress 5.3-158 prototype has a nominal generating capacity of 5.3 MW.  A smaller Cypress 4.8-158 (with a 4.8 MW rating) is currently under production at GE’s Salzbergen, Germany factory, and it is expected to be commissioned by the end of the 2019.  Both have a rotor diameter of 158 meters (518.3 ft).

Anatomy of a GE Cypress wind turbine. Source:  GE

GE reports that the Cypress platform is “powered by a revolutionary two-piece blade design that makes it possible to use larger rotors and site the turbines in a wider variety of locations. The Annual Electricity Production (AEP) improvements from the longer rotors help to drive down Levelized Cost of Electricity (LCOE), and the proprietary blade design allows these larger turbines to be installed in locations that were previously inaccessible.” Site accessibility can be limited by the practicality of ground transportation of single-piece blades that can be nearly 91.4 meters (300 feet) long.

1.2 GE LM 88.4 P, the longest one-piece rotor blade in the world

LM Wind Power, a GE Renewable Energy business, has delivered the longest one-piece wind turbine blades built to date, the LM 88.4 P, which measure 88.4 meters (290 ft) long.  Three of these giant blades are installed onshore in Denmark on an Adwen’s AD 8-180 wind turbine, which has an 8 MW nominal generating capacity and a 180 meter (590.5 ft) rotor diameter.  You can get a sense of the size of an LM 88.4 P in the following photo showing a rotor blade leaving the factory.

88.4 meter (290 ft) LM 88.4 P wind turbine rotor blade 
leaving the factory.  Source: LM Wind Power

1.3 GE Haliade-X platform

GE is developing an even larger wind turbine platform, the Haliade X, which will become the world’s largest wind turbine when it is completed.  This 12 MW platform, which is being developed primarily for offshore wind farms, features 107 meter (351 ft) long one-piece blades and a 220 meter (722 ft) rotor diameter. The first prototype unit will be installed onshore near Rotterdam, Netherlands, where it will stand 259 meters (850 ft) tall, from the base of the tower to the top of the blade sweep.

Anatomy of a GE 12 MW Haliade-X wind turbine. Source: GE

Construction of the prototype Haliade-X wind turbine began in 2019.  The first blade is shown in the photo below. After securing a “type certificate” for the Haliade-X platform, GE plans to start selling this wind turbine commercially as early as 2021. The near-term market focus appears to be new wind turbines sited in the North Sea.

The first 107 meter (351 ft) Haliade-X blade at the factory in Cherbourg, France.  Source GE Renewable Energy

1.4 Siemens Gamesa SG 10.0-193 DD platform

In January 2019, Siemens Gamesa launched its next generation (Generation V) of very large offshore wind turbines, the SG 10.0-193 DD, which has a nominal generator rating of 10 MW, blade length of 94 meters (308 ft) and a rotor diameter of 193 meters (633 ft).  The nacelle housing the wind turbine hub and generator weighs up to 400 tons.

You’ll find the Siemens product brochure for this Generation V wind turbine here: https://www.siemensgamesa.com/en-int/-/media/siemensgamesa/downloads/en/products-and-services/offshore/brochures/siemens-gamesa-offshore-wind-turbine-sg-10-0-193-dd-en-double.pdf

The 10 MW Siemens SG 10.0-193 DD. Source: Siemens Gamesa

1.5 Vestas EnVestusTM platform

The EnVestusTM platform, which was introduced in 2019, is Vestas’ next generation in its evolution of wind turbines. The V162-5.6 MW has a rotor diameter of 162 meters (531 ft), which is the largest rotor size offered in the current EnVestusTM product portfolio.  Various tower sizes are offered, with hub heights up to 166 meters (545 ft).  With this tallest tower, the blade sweep of a V162-5.6 MW wind turbine reaches a height of 247 meters (810 ft).

V162-5.6 MW nacelle.  Source:  Vestas

The trend in Vestas wind turbine maximum rotor size is evident in the following diagram.  In comparison, the largest GE wind turbine, the Haliade-X will have a rotor diameter of 220 meter (722 ft), and the largest Siemens Generation V wind turbine will have a rotor diameter of 193 meters (633 ft).  

Source: Vestas

You can read and download the EnVestusTMproduct line brochure here: https://nozebra.ipapercms.dk/Vestas/Communication/Productbrochure/enventus/enventus-product-brochure/?page=1

2. Transporting very large wind turbine components

The manufacturer’s efforts to improve wind turbine generating and economic performance has resulted in increasingly larger machine components, which are challenging the limits of today’s transportation infrastructure as the components are moved from the manufacturer’s factories to the installation sites.  Here, we’ll look at the various ways these large components are transported.

2.1 Transportation of wind turbine components by land

Popular Mechanics reported that, “Moving long turbine blades is such a logistical nightmare that the companies involved sometimes resort to building new roads for the sole purpose of moving blades.” Transporting wind turbine tower and nacelle components can be equally challenging.  You’ll find an interesting assessment by CGS Labs of the challenges of wind farm ground transportation planning at the following link: https://www.cgs-labs.com/Software/Autopath/Articles/Windturbinetransport.aspx

As noted previously, the GE one-piece LM 88.4 P, which is 88.4 meters (290 ft) long, is the longest wind turbine rotor blade currently in service.  You can watch a short video of a single LM 88.4 P blade being transported 218 km (135 miles) to the construction site at the following link.  Total transport weight was 60 tons (120,000 lb, 54,431 kg). https://www.lmwindpower.com/en/products-and-services/blade-types/longest-blade-in-the-world

88.4 meter (290 ft) LM 88.4 P wind turbine blade during transport. 
Source: Screenshot from LM Wind Power video

Specialized trucks are employed to negotiate existing roads. Examples of difficult transportation situations are shown in the following photos.

Siemens 75 m (243 ft) rotor blade was transported 320 km (199 miles) by road.  Source: utilities-me.com, 14 Aug 2012
Making a sharp turn with a specialized truck for transporting a
 Vestas V117 57.5 meter (189 ft) wind turbine blade.  
Source: CNN.com, 5 October 2017

Watch a short 2017 video of this maneuver here:  https://www.youtube.com/watch?v=rxvuMv2MED0

Specially-designed trucks move 52.4 meter (172 foot) long wind turbine blades on narrow roads on Baoding Mountain in China.  Source:  Business Insider, 2 Mar 2017

Watch a short 2015 video of this amazing truck convoy here:  https://www.youtube.com/watch?v=1cnHui4pFBU

2.2. Transportation of wind turbine components by sea

The single-piece blades for the GE Haliade X wind turbine are so long that they couldn’t be transported by land from GE’s existing factories.  Therefore, a new LM Wind Power blade factory for the offshore wind market was built in Cherbourg, France, on the banks of the English Channel in Normandy.  This factory can load blades directly onto ships for delivery to offshore wind turbine sites.

GE wind turbine blades shipped by sea.  
Source:  LM Wind Power

In December 2016, Siemens Gamesa reported, “When our new factories in Hull, England and Cuxhaven, Germany become fully operational, and both Ro-Ro (“roll-on, roll-off”) vessels are in service as interconnection of our manufacturing and installation network, we expect savings of 15-20 percent in logistics costs compared to current transport procedures. This is another important contributor reducing the cost of electricity from offshore wind.”

The Hull, UK rotor blade factory, located at the Alexandra Docks on the harbor, was completed in 2016.  The Esbjerg, Denmark factory also is located on the harbor with direct access to shipping.

In 2018, Siemens Gamesa opened its modern factory in Cuxhaven, Germany for manufacturing offshore wind turbine nacelles.  These three Siemens wind turbine factories have direct Ro-Ro access to shipping.In November 2016, Siemens commissioned its first specialized Ro-Ro transport vessel, the Rotra Vente.  This ship is designed to transport multiple heavy nacelles, or up to nine tower sections, or three to four sets of rotor blades, depending on what else is being transported.  A second specialized Ro-Ro transport vessel, the Rotra Mare, was commissioned in the spring of 2017 to transport tower sections and up to 12 rotor blades.  These specialized transport vessels link the Siemens factories and transport the finished wind turbine components to the respective installation harbor.

The Rotra Vente provides Ro-Ro access for large Siemens wind turbine components.  Source: Siemens

2.3. Transportation of wind turbine components by airship

For more than two decades, there has been significant interest in the use of modern lighter-than-air craft and hybrid airships in a variety of heavy-lift roles.  One such role is the transportation of large wind turbine components.  Airships offer the potential to transport the components quickly between factory and installation site without the constraints of current ground and sea transportation networks.

Three examples of airship concepts for transporting wind turbine components are described below. 

Hybrid airships

In 2017, Lockheed-Martin proposed its LMH-1 hybrid airship to deliver large wind turbine components weighing up to 23.5 tons (47,000 lb; 21,000 kg).  The LMH-1 will be capable of flying 1,400 nautical miles (2,593 km) at a speed of about 70 knots (80 mph, 129 kph).  Lockheed-Martin is expected to fly the commercial prototype of its LMH-1 hybrid airship in 2019. You can read Lockheed-Martin’s proposal for airship transport of wind turbine components here: https://www.lockheedmartin.com/content/dam/lockheed-martin/eo/documents/webt/transporting-wind-turbine-blades.pdf

This type of airship conducts short takeoff and landing (STOL) operations when transporting heavy loads, but can operate from relatively unprepared sites.  When off-loading heavy cargo, this airship must take on ballast at the landing site. 

After LMH-1, Lockheed Martin has plans to build a medium-size (90 ton cargo) hybrid airship that would be more competitive with trucking and rail transport.  

Anatomy of the LMH-1 hybrid airship.  Source:  Lockheed Martin

Variable buoyancy airships

In January 2013, Worldwide Aeros Corp. (Aeros), located in Montebello, CA, conducted the first “float test” of their Dragon Dream variable buoyancy airship.  More recently, Aeros has reported that they are working on the first commercial prototype of a larger variable buoyancy airship to be known as the ML866 / Aeroscraft Gen 2, which will be 169 meters (555 ft) long.  This airship is being designed with great range (3,100 nautical miles; 5,741 km) and a cruise speed of 100 – 120 knots.  The ML866 will have a cargo capacity of 66 tons (132,000 lb; 59,874 kg).  The first ML866 prototype is not expected to fly before the early 2020s.

This type of airship is designed to conduct vertical takeoff and landing (VTOL) operations with a full cargo load, and can hover above a site and take on or deliver cargo without landing and without transferring ballast to/from the ground site.

Concept drawing of an Aeroscraft variable buoyancy airship delivering wind turbine blades to a site.  Source: Worldwide Aeros Corp.

Semi-rigid airships

The KNARR initiative is a project created by two Danish design architects, Rune Kirt and Mads Thomsen to design a freight solution using modern airships to reduce the cost and energy consumption of today’s wind turbine freight business and make the logistics for wind turbine freight simpler and more efficient.  Their main point is that transportation and installation costs can be up to 60% of the total cost of a new wind turbine, and these activities have a large carbon footprint.  Their solution is a modern airship that is designed specifically for transporting very large and heavy wind turbine components directly from the manufacturer’s factory to the installation  site. For their work, they were awarded both the Danish Design Center’s Special Prize and the International Core77 Design “Speculative Concept.”.  You can read more about the firm, KIRT x THOMSEN aps, and the KNARR initiative here: https://www.kirt-thomsen.com/case10_airship-knarr

and here: https://projectknarr.wordpress.com/what-is-knarr/

The KNARR semi-rigid airship would be 360 meters (1,181 ft) long and would carry the wind turbine components in a large internal cargo bay. This type of airship is designed to conduct VTOL operations with a full cargo load.  When off-loading heavy cargo, this airship must take on ballast at the landing site.

The KNARR airship is a concept only.  No prototype is being built at this time.  You can view a short video defining the wind turbine transport application of KNARR airship here: https://vimeo.com/21023051

Concept drawing of a KNARR airships it lifts off after making a delivery.
Source: https://www.kirt-thomsen.com/
Concept drawing of a KNARR airship flying over a wind farm.
Source: https://www.kirt-thomsen.com/

3. Conclusions

The scale of the latest generation of wind turbines, particularly the GE LM 88.4 P, which measure 88.4 meters (290 ft) long, is approaching the limits of existing ground transportation infrastructure to handle delivery of such blades from the factory to the installation site.  GE’s introduction of two-piece blades on their new Cypress platform will significantly improve the logistics for delivering these large blades to installation sites.

Siemens’ practice of siting its wind turbine component factories with ready access to Ro-Ro shipping at an adjacent port facility greatly reduces the complexity of delivering large components to a port near an installation site.  GE has adopted the same approach with their latest factory for manufacturing the Haliad-X rotor blades in Cherbourg, France, on the English Channel.

Airships could revolutionize the transportation of large, heavy items such as wind turbine components.  However, the earliest likely candidate, the Lockheed Martin LMH-1 will not be available until the early 2020s and will  be limited to a maximum load of 23.5 tons (47,000 lb; 21,000 kg).  It seems unlikely that larger heavy-lift airships will be introduced before about 2025. 

So, in the meantime, we’ll see the largest wind turbines being installed in offshore sites.  For onshore sites, we’ll see more creative ground transportation schemes, and, probably, a broader introduction of multi-part rotor blades.

4. Recommended additional reading on wind turbines:

Energy Literacy

I was impressed in 2007 by the following chart in Scientific American, which shows where our energy in the U.S. comes from and how the energy is used in electricity generation and in four consumer sectors. One conclusion is that more than half of our energy is wasted, which is clearly shown in the bottom right corner of the chart. However, this result shouldn’t be surprising.

2007 USA energy utilizationSource: Scientific American / Jen Christiansen, using LLNL & DOE 2007 data

The waste energy primarily arises from the efficiencies of the various energy conversion cycles being used. For example, the following 2003 chart shows the relative generating efficiencies of a wide range of electric power sources. You can see in the chart that there is a big plateau at 40% efficiency for many types of thermal cycle power plants. That means that 60% of the energy they used is lost as waste heat. The latest combined cycle plants have demonstrated net efficiencies as high as 62.22% (Bouchain, France, 2016, see details in my updated 17 March 2015 post, “Efficiency in Electricity Generation”).

Comparative generation  efficiencies-Eurelectric 2003Source: Eurelectric and VGB PowerTech, July 2003

Another source of waste is line loss in electricity transmission and distribution from generators to the end-users. The U.S. Energy Information Administration (EIA) estimates that electricity transmission and distribution losses average about 6% of the electricity that is transmitted and distributed.

There is an expanded, interactive, zoomable map of U.S. energy data that goes far beyond the 2007 Scientific American chart shown above. You can access this interactive map at the following link:

http://energyliteracy.com

The interactivity in the map is impressive, and the way it’s implemented encourages exploration of the data in the map. You can drill down on individual features and you can explore particular paths in much greater detail than you could in a physical chart containing the same information. Below are two example screenshots. The first screenshot is a top-level view. As in the Scientific American chart, energy sources are on the left and final disposition as energy services or waste energy is on the right. Note that waste energy is on the top right of the interactive map.

Energy literacy map 1

The second screenshot is a more detailed view of natural gas production and utilization.

Energy literacy map 2

As reported by Lulu Chang on the digitaltrends.com website, this interactive map was created by Saul Griffith at the firm Otherlab (https://otherlab.com). You can read her post at the following link:

http://www.digitaltrends.com/home/otherlab-energy-chart/

I hope you enjoy exploring the interactive energy literacy map.

The Cargo Bicycle – An Idea Whose Time Has Come, or Has it Been Here All Along?

There has been increasing interest in the U.S. in cargo bicycles for making pickups and deliveries, particularly in inner cities with high traffic volumes and limited parking. Human or electric-powered cargo bicycles offer obvious environmental advantages over traditional, much larger gas or diesel powered delivery vehicles.

In February 2017 IKEA will be introducing a multifunctional, affordable, “city bike” called the Sladda. In addition to IKEA’s own interpretation of conventional bicycle features, the Sladda can be equipped with a variety of cargo carriers:

  • Front basket that’s rated at 10 kg (22 pounds)
  • Rear rack that’s rated at 25 kg (55 pounds)
  • Clip-on pannier (bicycle bag), which requires rear rack and converts into a backpack
  • Trailer that’s rated to haul 49 kg (108 pounds).

The rated load of the bicycle itself is 160 kg (352 pounds), including the weight of rider.

IKEA Sladda-2

Sladda configured as a cargo bicycle.  Source: IKEA

You’ll find details on the Sladda on the IKEA website at the following link:

http://www.ikea.com/us/en/

Xtracycle offer the Cargo Node and Edgerunner cargo bicycles. The folding Cargo Node, shown below, has a 159 kg (350 pound) carrying capacity, including the weight of the rider. The Edgerunner is a non-folding bicycle with a 182 kg (400 pound) carrying capacity. Both can be configured with a variety of racks. You’ll find more information at the following link:

http://www.xtracycle.com

 Xtacycle cargo bikeCargo Node.  Source: Xtracycle

Cargo bicycles may be trending in the U.S., but they have been used for many decades in Europe, particularly in Scandinavian countries, and they probably have been used just as long in Asia.

On a recent trip to China and Cambodia I found that 2- and 3-wheel cargo bicycles were very common and some were capable of carrying impressive loads. It seemed the concept of “rated load” never was an issue. Also common in China and Cambodia were 3-wheel cargo scooters and a range of small cargo vehicles that were part motorcycle and part truck. These small cargo vehicles seemed well suited for use in very high volume, relatively slow moving city traffic. Following are photos of several of the cargo bicycles, scooters and motorcycles I saw on the trip.

The cargo bicycles offered by IKEA and Xtracycle are nice, but they really don’t break new ground in the use of bicycles as cargo carriers. What is new is that individuals and businesses in the U.S. are expressing increasing interest in cargo bicycles, and other forms of small urban delivery vehicles. Next time you’re stuck in city traffic, you may be passed by a cargo bicycle in the bike lane.

Basic cargo bicycleBasic cargo bicycle in Xi’an, China

Streetsweepers cargo bikeStreet sweeper’s cargo bicycle in Xi’an, China

Cargo bike with cardboardCargo bicycle in Xi’an, China

Heavy load cargo bikeHeavy cargo bicycle in Xi’an, China

Cambodian vendor cargo bikeCargo bicycle in Cambodia

Cargo scooter beijingLoading an electric cargo scooter in Beijing, China

Cargo scooter LhasaCargo scooter in traffic in Lhasa, Tibet

cargo scooter big loadElectric cargo scooter/truck with a large volume load in Beijing, China

Cargo motorcycle tractor trailerCargo motorcycle tractor/trailer in Cambodia

Quadrennial Energy Review

On 9 January 2014 the Administration launched a “Quadrennial Energy Review” (QER) to examine “how to modernize the Nation’s energy infrastructure to promote economic competitiveness, energy security, and environmental responsibility…” You can read the Presidential Memorandum establishing the QER at the following link:

https://www.whitehouse.gov/the-press-office/2014/01/09/presidential-memorandum-establishing-quadrennial-energy-review

You can get a good overview of the goals of the QER in a brief factsheet at the following link:

https://www.whitehouse.gov/the-press-office/2015/04/21/fact-sheet-administration-announces-new-agenda-modernize-energy-infrastr

On April 21, 2015, the QER Task Force released the “first installment” of the QER report entitled “Energy Transmission, Storage, and Distribution Infrastructure.” The Task Force announcement stated:

“The first installment (QER 1.1) examines how to modernize our Nation’s energy infrastructure to promote economic competitiveness, energy security, and environmental responsibility, and is focused on energy transmission, storage, and distribution (TS&D), the networks of pipelines, wires, storage, waterways, railroads, and other facilities that form the backbone of our energy system.”

The complete QER 1.1 report or individual chapters are available at the following link:

https://energy.gov/epsa/quadrennial-energy-review-first-installment

QER 1.1 contents are listed below:

QER 1.1 contentOn January 6, 2017, the QER Task Force released the “second installment” of the QER report entitled “Transforming the Nation’s Electricity System.” The Task Force announcement stated:

“The second installment (QER 1.2) finds the electricity system is a critical and essential national asset, and it is a strategic imperative to protect and enhance the value of the electricity system through modernization and transformation. QER 1.2 analyzes trends and issues confronting the Nation’s electricity sector out to 2040, examining the entire electricity system from generation to end use, and within the context of three overarching national goals: (1) enhance economic competitiveness; (2) promote environmental responsibility; and (3) provide for the Nation’s security.

The report provides 76 recommendations that seek to enable the modernization and transformation of the electricity system. Undertaken in conjunction with state and local governments, policymakers, industry, and other stakeholders, the recommendations provide the building blocks for longer-term, planned changes and activities.”

The complete QER 1.2 report or individual chapters are available at the following link:

https://energy.gov/epsa/quadrennial-energy-review-second-installment

QER 1.2 contents are listed below:

QER 1.2 contentI hope you take time to explore the QERs. I think the Task Force has collected a great deal of actionable information in the two reports. Converting this information into concrete actions will be a matter for the next Administration.

Airbus Delivers its 10,000th Aircraft

Airbus was founded on 18 December 1970 and delivered its first aircraft, an A300B2, to Air France on 10 May 1974. This was the world’s first twin-engine, wide body (two aisles) commercial airliner, beating Boeing’s 767, which was not introduced into commercial service until September 1982. The A300 was followed in the early 1980s by a shorter derivative, the A310, and then, later that decade, by the single-aisle A320. The A320 competed directly with the single-aisle Boeing 737 and developed into a very successful family of single-aisle commercial airliners: A318, A319, A320 and A321.

On 14 October 2016, Airbus announced the delivery of its 10,000th aircraft, which was an A350-900 destined for service with Singapore Airlines.

EVE-1236Source: Airbus

In their announcement, Airbus noted:

“The 10,000th Airbus delivery comes as the manufacturer achieves its highest level of production ever and is on track to deliver at least 650 aircraft this year from its extensive product line. These range from 100 to over 600 seats and efficiently meet every airline requirement, from high frequency short haul operations to the world’s longest intercontinental flights.”

You can read the complete Airbus press release at the following link:

http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/-9b32c4364a/

As noted previously, Airbus beat Boeing to the market for twinjet, wide-body commercial airliners, which are the dominant airliner type on international and high-density routes today. Airbus also was an early adopter of fly-by-wire flight controls and a “glass cockpit”, which they first introduced in the A320 family.

In October 2007, the ultra-large A380 entered service, taking the honors from the venerable Boeing 747 as the largest commercial airliner.   Rather than compete head-to-head with the A380, Boeing opted for stretching its 777 and developing a smaller, more advanced and more efficient, all-composite new airliner, the 787, which was introduced in airline service 2011.

Airbus countered with the A350 XWB in 2013. This is the first Airbus with fuselage and wing structures made primarily of carbon fiber composite material, similar to the Boeing 787.

The current Airbus product line comprises a total of 16 models in four aircraft families: A320 (single aisle), A330 (two aisle wide body), A350 XWB (two aisle wide body) and A380 (twin deck, two aisle wide body). The following table summarizes Airbus commercial jet orders, deliveries and operational status as of 30 November 2016.

Airbus orders* Includes all models in this family. Source: https://en.wikipedia.org/wiki/Airbus

Boeing is the primary competitor to Airbus. Boeing’s first commercial jet airliner, the 707, began commercial service Pan American World Airways on 26 October 1958. The current Boeing product line comprises five airplane families: 737 (single-aisle), 747 (twin deck, two aisle wide body), 767 (wide body, freighter only), 777 (two aisle wide body) and 787 (two aisle wide body).

The following table summarizes Boeing’s commercial jet orders, deliveries and operational status as of 30 June 2016. In that table, note that the Boeing 717 started life in 1965 as the Douglas DC-9, which in 1980 became the McDonnell-Douglas MD-80 (series) / MD-90 (series) before Boeing acquired McDonnell-Douglas in 1997. Then the latest version, the MD-95, became the Boeing 717.

Boeing commercial order status 30Jun2016

Source: https://en.wikipedia.org/wiki/Boeing_Commercial_Airplanes

Boeing’s official sales projections for 2016 are for 740 – 745 aircraft. Industry reports suggest a lower sales total is more likely because of weak worldwide sales of wide body aircraft.

Not including the earliest Boeing models (707, 720, 727) or the Douglas DC-9 derived 717, here’s how the modern competition stacks up between Airbus and Boeing.

Single-aisle twinjet:

  • 12,805 Airbus A320 family (A318, A319, A320 and A321)
  • 14,527 Boeing 737 and 757

Two-aisle twinjet:

  • 3,260 Airbus A300, A310, A330 and A350
  • 3,912 Boeing 767, 777 and 787

Twin aisle four jet heavy:

  • 696 Airbus A340 and A380
  • 1,543 Boeing 747

These simple metrics show how close the competition is between Airbus and Boeing. It will be interesting to see how these large airframe manufacturers fare in the next decade as they face more international competition, primarily at the lower end of their product range: the single-aisle twinjets. Former regional jet manufacturers Bombardier (Canada) and Embraer (Brazil) are now offering larger aircraft that can compete effectively in some markets. For example, the new Bombardier C Series is optimized for the 100 – 150 market segment. The Embraer E170/175/190/195 families offer capacities from 70 to 124 seats, and range up to 3,943 km (2,450 miles).  Other new manufacturers soon will be entering this market segment, including Russia’s Sukhoi Superjet 100 with about 108 seats, the Chinese Comac C919 with up to 168 seats, and Japan’s Mitsubishi Regional Jet with 70 – 80 seats.

At the upper end of the market, demand for four jet heavy aircraft is dwindling. Boeing is reducing the production rate of its 747-8, and some airlines are planning to not renew their leases on A380s currently in operation.

It will be interesting to watch how Airbus and Boeing respond to this increasing competition and to increasing pressure for controlling aircraft engine emissions after the Paris Agreement became effective in November 2016.

Improving Heavy Tractor-Trailer Aerodynamics

My recent road trip to the Black Hills included long transit days each way on Interstate 90 through southern Minnesota and South Dakota. One thing I noticed was that many of the heavy tractor-trailers on this high speed route had streamlined tractors and / or trailers with a variety of aerodynamic devices that appeared useful for reducing drag and fuel consumption. In addition, there were quite a few trucks hauling double trailers.

The trucking industry’s ongoing efforts to improve heavy freight vehicle performance and economics was aided in 2004 by the creation of the SmartWay Transport Partnership, which is administered by the Environmental Protection Agency (EPA). SmartWay® is a voluntarily program for achieving improved fuel efficiency and reducing the environmental impacts from freight transport. The goal is, “to move more freight, more mile, with lower emissions and less energy.”

EPA SmartWay

SmartWay® is promoting the following strategies to help the heavy trucking industry meet this goal:

  • Idle reduction
  • Speed control
  • Driver training
  • Aerodynamics
  • Tire technologies
  • Lubricants
  • Hybrid power trains
  • Improved freight logistics
  • Vehicle weight reduction
  • Intermodal freight capability
  • Alternative fuels
  • Long combination vehicles (LVCs, such as double trailers)

The SmartWay® website is at the following link:

https://www.epa.gov/smartway

You’ll find an interesting Fall 2014 presentation on the SmartWay Transport Partnership at the following link:

http://www.mmta.com/document_upload/SmartWay%20and%20Truck%20Drivers.pdf

Key points from this presentation include the following:

  • Freight transportation is a cornerstone of the U.S. economy. As of 2012, U.S. businesses spent $1 trillion to move $12 trillion worth of goods (8.5% of GDP).
  • Freight accounts for 9% of all U.S. greenhouse gas (GHG) emissions, and trucking is the dominant mode. (Note: There were about 2 million tractor-trailers in active service in the U.S. in 2011).
  • A truck or trailer fitted out with all the essential efficiency features can be sold as a SmartWay® “designated” model. A “designated” tractor-trailer combo can be as much as 20% more fuel-efficient than the comparable standard model.

In May 2012, the Canadian Center for Surface Transportation Technology (CSTT) issued technical report CSTT-HVC-TR-205, which is entitled, “Review of Aerodynamic Drag Reduction Devices for Heavy Trucks and Buses.” In Table 2 of this report, CSTT provides the following illustrative example of the relative power consumption of aerodynamic drag and rolling / accessory drag as a function of vehicle speed.

CSTT truck power consumption tableRelative contributions to total vehicle drag. Source: CSTT

In this example, rolling / accessory drag dominates at lower speeds typical of urban driving. At 50 mph (80 kph) aerodynamic drag and rolling / accessory drag are approximately equal. At higher speeds, aerodynamic drag dominates power consumption. The speed limit on I-90 in South Dakota typically is 80 mph (129 kph). At this speed the aero drag contribution is even higher than shown in the above table

Key points from this CSTT report include the following:

  • For tractor-trailers, pressure drag is the dominant component of vehicle drag, due primarily to the large surface area facing the main flow direction and the large, low-pressure wake resulting from the bluntness of the back end of the vehicle.
  • Aero-tractor models can reduce pressure drag by about 30% over the boxy classic style tractor.
  • Friction drag occurring along the sides and top of tractor-trailers makes only a small contribution to total drag (10% or less), so these areas are not strong candidates for drag-reduction technologies.
  • The gap between the tractor and the trailer has a significant effect on total drag, particularly if the gap is large. Eliminating the gap entirely could reduce total drag by about 7%.
  • Side skirts or underbody boxes prevent airflow from entering the under-trailer region. These types of aero devices could reduce drag by 10 – 15%.
  • Wind-tunnel and road tests have demonstrated that a “boat tail” with a length of 24 – 32 inches is optimal for reducing drag due to the turbulent low-pressure region behind the trailer
  • Adding a second trailer to form an LCV, and thus doubling the freight capacity, results in a very modest increase in drag coefficient (as low as about 10%) when compared to a single trailer vehicle.
  • In cold Canadian climates, the aerodynamic drag in winter can be nearly 20% greater than at standard conditions, due to the ambient air density. For highway tractor-trailers, this results in about a 10% increase in fuel consumption from drag when compared to the reference temperature, further emphasizing the importance of aerodynamic drag reduction strategies for the Canadian climate.

You can read an executive summary of this CSTT report at the following link:

https://www.tc.gc.ca/eng/programs/environment-etv-menu-eng-2939.html

You can download the complete 100-page report here:

https://www.tc.gc.ca/media/documents/programs/AERODYNAMICS_REPORT-MAY_2012.pdf

The 2012 CSTT report includes a note that Mercedes had introduced a concept trailer that is reported to provide an 18% reduction in drag for a full European tractor-trailer combination.

Mercedes-aero-trailer-4 Source: Mercedes

You can view a short 2012 YouTube video on a similar Mercedes aero tractor-trailer at the following link:

https://www.youtube.com/watch?v=I1Sq2Q8YEYw

The U.S. firm STEMCO offers two aero kits for improving conventional tractor-trailer aerodynamics:

  • TrailerTail®, which is installed at the back of the trailer, reduces the magnitude of the turbulent low-pressure area that forms behind the trailer at high speeds.
  • EcoSkirt®, which is installed under the trailer, reduces aerodynamic drag under the trailer where air hits the trailer’s rear axles. The side fairings streamline and guide the air around the sides and to the back of the trailer.

Both of these aerodynamic devices are shown in the following figure.     This was a tractor-trailer configuration that I saw frequently on I-90.

Stemco 1794Source: STEMCO

STEMCO allocates the primary sources of tractor-trailer aerodynamic drag as shown in the following figure.

Stemco contributions to semi aero dragSource: STEMCO

STEMCO claims the following benefits from their aero kits:

“TrailerTail® fuel savings complement other aerodynamic technologies. A TrailerTail® reduces aerodynamic drag by over 12% equating to over 5% fuel efficiency improvement at 65 mph (105 kph) and over 12% fuel efficiency improvement when combined with STEMCO’s side skirts and other minor trailer modifications.”

STEMCO TrailerTail® meets the SmartWay® advanced trailer end fairings criteria for a minimum of 5% fuel savings and the STEMCO EcoSkirt® meets the advanced trailer skirts qualifications with greater than 5% fuel savings. The payback period for these aero devices is expected to be about one year.

You’ll find more details on STEMCO’s tractor-trailer drag reduction products, including a short “Aerodynamics 101” video, at the following link:

http://www.stemco.com/aero-u/

More details on TrailerTail®, including its automatic deployment and operational use, are shown in a short video at the following link:

https://www.youtube.com/watch?v=qPrM3-CCth8

Another firm, Aerotech Caps, offers a range of aero kits for improving truck aerodynamics, including aerodynamic wheel covers, aerodynamic trailer skirts, tail fairings and vortex generators. You can see their product line at the following link:

http://www.aerotechcaps.com/index.html

Aero wheel covers

Source: Aerotech Caps

Aerotech Caps claims that its aerodynamic wheel covers deliver about 2.4% increased miles per gallon when installed on rear tractor and all trailer wheels. Payback period for this aero kit is expected to be about one year.

The future of heavy freight vehicles is likely to include increasingly aerodynamic tractor-trailers. One particularly elegant concept vehicle is shown below.

Future TruckjpgConcept aero-optimized heavy freight vehicle. Source: http://forums.fourtitude.com

In spite of all of these opportunities for improving heavy tractor-trailer aerodynamics, there always will be cases when few of these are actually practical. As evidence, I offer the following photo taken at 80 mph on I-90 in South Dakota during my recent road trip. How do you optimize that giant drag coefficient?

DSC_5401Source: Author photo

 

Modern Airships – Part 1

This post was updated on 1 May 2019.

  1. Introduction

For more than two decades, there has been significant interest in the use of modern lighter-than-air craft and hybrid airships in a variety of military, commercial and other roles, including:

  • Heavy cargo carriers serving remote and/or unimproved sites
  • Persistent optionally-manned surveillance platforms
  • Maritime surveillance / search and rescue
  • Disaster relief, particularly in areas not easily accessible by other means
  • Unmanned aerial vehicle (UAV) / unmanned air system (UAS) carrier
  • Commercial flying cruise liner
  • Airship yacht

In spite of the significant interest, actual military, commercial and other customers have been slow coming to the marketplace with firm orders, the airship manufacturers have been slow in developing and delivering advanced airships that meet their customer’s needs, and funding was prematurely curtailed for several ambitious projects.  This uncertain business climate seems likely to change by the early 2020s, when several different heavy-lift airships are expected to be certified by airworthiness authorities and ready for mass production and sale to interested customers.

One of the very significant factors driving interest in modern airships is that they offer the potential to link isolated regions with the rest of the world while doing so in a way that should have lower environmental impacts than other transportation alternatives for those regions. This target market for airships exists in more than two-thirds of the world’s land area where more than half the world’s population live without direct access to paved roads and reliable ground transportation.

This matter is described well in a 21 February 2016 article by Jeanne Marie Laskas, “Helium Dreams – A new generation of airships is born,” which is posted on The New Yorker website at the following link:

https://www.newyorker.com/magazine/2016/02/29/a-new-generation-of-airships-is-born

In this article, Boris Pasternak, CEO of airship manufacturer Worldwide Aeros Corp., commented:

“The biggest challenge in using lighter-than-air technology to lift hundreds of tons of cargo is not with the lifting itself—the larger the envelope of gas, the more you can lift—but with what occurs after you let the stuff go. ‘When I drop the cargo, what happens to the airship?’ Pasternak said. ‘It’s flying to the moon.’ An airship must take on ballast to compensate for the lost weight of the unloaded cargo, or a ground crew must hold it down with ropes.”

Among the many current designers and manufacturers of large airships, this matter of “load exchange” (i.e., maintaining the airship’s net buoyancy within certain limits while loading and unloading cargo and passengers) is handled in several different ways depending on the type of airship involved.  Some load exchange solutions require ground infrastructure for external ballast handling, while others require no such infrastructure.  The solution chosen for accomplishing a load exchange strongly influences how an airship can be operationally employed and where it can deliver its payload.

  1. Types of modern airships

The term “aerostat” broadly includes all lighter than air vehicles that gain lift through the use of a buoyant gas. Aerostats include unpowered balloons (tethered or free-flying) and powered airships.

There are three main types of powered airships: conventional, hybrid, and variable buoyancy / fixed volume.  The basic characteristics of each airship type are described below.

Basic characteristics of conventional airships

Conventional airships are lighter-than-air (LTA) vehicles that operate at or near neutral buoyancy.  Airships of this type include non-rigid blimps, rigid zeppelins, and semi-rigid airships. The lifting gas (helium) generate 100% of the lift at low speed, thereby permitting vertical takeoff and landing (VTOL) operations and hovering.  Various types of propulsors may be used for cruise flight propulsion and for low-speed maneuvering and station keeping.

  • Non-rigid airships (blimps): These airships have a flexible envelope that defines the shape of the airship, contains the lifting gas cells and ballonets, and supports the load of a gondola, engines and payload.
  • Rigid airships (zeppelins):These airships have a lightweight, rigid airframe that defines their exterior shape. The rigid airframe supports the gondola, engines and payload.  Lifting gas cells and ballonets are located within the rigid airframe.
  • Semi-rigid airships: These airships have a rigid internal structural framework that supports loads. A flexible envelope is installed over the structural framework and contains the lifting gas cells and ballonets.

After being loaded and ballasted before flight, conventional airships have little control over the in-flight buoyancy of the airship. Control can be exercised over ballast, lifting gas and the ballonets as described below.

  • Ballast: Conventional airships require adjustable ballast (i.e., typically water or sand) that can be added or removed as needed to establish a desired net buoyancy before flight.  Load exchanges require a corresponding ballast adjustment. If an airship is heavy and the desired buoyancy can’t be restored with the ballonets, ballast can be dumped in flight to increase buoyancy.
  • Lifting gas: Normally, there is no significant loss of lifting gas during flight.  If an airship is light and the desired buoyancy cannot be restored with the ballonets, it is possible to vent some lifting gas to the atmosphere to decrease static lift.
  • Ballonets:In conventional airships, the gas envelope is divided into a sealed main helium gas volume and separate gas volumes called “ballonets” that contain ambient air at atmospheric pressure. The ballonets are used to compensate for change in the volume of lifting gas and to make small changes in buoyancy by expanding or contracting the air volume to change the gross weight or the fore-and-aft trim of the airship.

On the ground, the ballonets may be inflated with air to make the airship negatively buoyant to simplify ground handling. To takeoff, the ballonets would be vented to the atmosphere, reducing the mass of air carried by the airship, allowing the helium gas volume to expand, and increasing buoyant lift.

As the airship gains altitude, external air pressure decreases, allowing the helium gas volume to expand within the gas envelope, into space previously occupied by the air in the ballonets, which vent a portion of their air content overboard. The airship reaches its maximum altitude, known as its “pressure height,” when the helium gas volume has expanded to fill the gas envelope and the ballonets are empty.  At this point, the airship’s mass is at a minimum and the helium lifting gas can expand no further.

To descend, a fan is used to inflate the ballonets with outside air, adding mass and slightly compressing the helium into a smaller volume. This action decreases buoyant lift. As the airship continues to descend into the denser atmosphere, the helium gas volume continues to compress and the ballonets become proportionately larger.  Ballonet inflation is controlled to manage buoyancy as the airship approaches the ground for a landing.

In flight, inflating only the fore or aft ballonet, and allowing the opposite ballonet to deflate, will make the bow or stern of the airship heavier and change the pitch of the airship.  These operating principles are shown in the following diagrams of a blimp with two ballonets, which are shown in blue.

Blimp with ballonets (blue).  Source:  zeppelinfan.de

Basic characteristics of hybrid airships

These are heavier-than-air (HTA) vehicles that are “semi-buoyant.”  This means that the lifting gas provides only a fraction of the needed lift (typically 60 – 80%) and the balance of the lift needed for flight is generated by other means, such as vectored thrust engines and aerodynamic lift from the fuselage and wings during forward flight.

Sources of lift for a semi-rigid, inflated hybrid airship. Source: DoD 2012

General characteristics of hybrid airships include the following:

  • This type of airship requires some airspeed to generate aerodynamic lift.Therefore, it typically makes a short takeoff and landing (STOL).
  • Some hybrid airships may be capable of limited VTOL operations (i.e., when lightly loaded, or when equipped with powerful vectored thrust engines).
  • Like conventional airships, the gas envelope in hybrid airship is divided into helium gas volumes and separate volumes containing ambient air.
  • Hybrid airships are heavier-than-air and are easier to control on the ground than conventional airships.

There are two types of hybrid airships:  semi-rigid and rigid.

  • Semi-rigid hybrid airships: These airships have a structural keel or spine to carry loads, and a large, lifting-body shaped inflated fuselage containing the lifting gas cells and ballonets.  Operation of the ballonets to adjust net buoyancy and pitch angle is similar to their use on conventional airships.  These wide hybrid airships may have separate ballonets on each side of the inflated envelope to adjust the roll angle.  While these airships are heavier-than-air, they still generally require adjustable ballast to handle a load exchange involving a heavy load.
  • Rigid hybrid airships: These airships have a more substantial structure that defines the shape of the exterior aeroshell.  In some respects, these are semi-buoyant aircraft, with less buoyancy than the semi-rigid hybrid airships.  In exchange for the reduced buoyancy, handling on the ground is more like a conventional fixed-wing aircraft and load exchanges do not require external ballast.

Basic characteristics of variably buoyancy / fixed volume airships

 These are rigid airships that can become LTA or HTA, as the circumstances require.  These airships become heavier by compressing the helium lifting gas or ambient air:

  • Compressing the helium lifting gas into smaller volume tanks aboard the airship reduces the total lift generated by helium.
  • Compressing ambient air into pressurized tanks aboard the airship adds weight to the airship and thus decreases the net lift.

These airships become lighter by venting gas from the pressurized tanks:

  • Compressed helium lifting gas is vented back into the helium lift cells, increasing their volume and increasing lift.
  • Compressed air is vented to the atmosphere, reducing the weight of the airship and thus increasing net lift.

This buoyancy control process is accomplished without taking on external ballast or venting the lifting gas to the atmosphere.

General characteristics of variable buoyancy airships include the following:

  • Variable lift airships are capable of VTOL operations and hovering with a full load.
  • The buoyancy control system enables in-flight load exchanges from a hovering airship without the need for external ballast.
  • On the ground, variable lift airships can make themselves heavier-than-air to facilitate load exchanges without external infrastructure or ballast.
  1. The scale of large cargo airships

Some of the advanced airship concepts being developed, especially for future heavy cargo carriers, will result in extremely large air vehicles on a scale we haven’t seen since the heyday of the giant zeppelins in the 1930s.  Consider the following semi-rigid hybrid airships shown to scale with contemporary fixed-wing cargo aircraft.

Size comparison for hybrid airships required for various lift applications. Source: DoD 2012

  1. Specific airships

Details on the airships listed in the following tables are provided in individual sections.

Megalifter, CargoLifter CL160, Project Walrus and SkyCat are included because they are of historical interest as early, though unsuccessful, attempts to develop very large cargo airships.  Concepts and technologies developed on these airship projects have promoted the development of other modern airships.

Among the airships in the above list, the following have actually flown: 

  • Zeppelin NT 07
  • Skybus 80K
  • Aeroscraft Dragon Dream
  • Hybrid Air Vehicles HAV-304
  • Hybrid Air Vehicles Airlander 10 prototype
  • Lockheed Martin P-791

As of May 2019, the Zeppelin NT 07 is the only advanced airship in this list that is flying regularly in commercial service. The others in the list are under development or remain as concepts only.

By the early 2020s, we likely will see several advanced airships on this list completing their development cycle and airworthiness certification.  The leading candidates seem to be:

  • Aeroscraft ML866 / Aeroscraft Gen 2
  • Airlander 10
  • Lockheed Martin LMH-1

Here are the links to the individual airships descriptions:

Conventional airships:

Variable buoyancy, fixed volume airships: 

 Hybrid (semi-buoyant) airships: