WheelTug
Encyclopedia
WheelTug is a fully integrated ground propulsion
system for aircraft which puts a high torque electric motor into the hub of the nose wheel to allow for backwards movement without the use of pushback tugs and to allow for forward movement without using the aircraft's engines. WheelTug will drive the aircraft with power supplied by the onboard APU (Auxiliary Power Unit). The first version is being designed for the Boeing 737NG with delivery expected in 2012.
Pushback
errors can damage the aircraft and the pushback tug http://www.flightglobal.com/articles/2010/09/11/347208/video-delta-747-shunts-tow-tractor-at-gate.html or can injure or kill the tug operator. Collisions with the tug can take aircraft out of operation for days and have a cascading effect that adversely affects the flight and passenger schedules for the rest of the day, while smaller accidents include tow bar hookup where the tug operator risks injury to the hands.
Jet Blast
behind the engines and the area in front of the engines (Intake Danger Zone) are eliminated in the gate area. When no physical gate exists and passengers disembark onto the open tarmac, then with certain aircraft configurations it is normally necessary to let the engines cool down before a hatch is opened to disembark passengers.
As many of the risk factors (tug collisions, jet blast, jet intake) will be eliminated, it is expected that WheelTug equipped aircraft will have reduced insurance premiums.
Upon receiving clearance from the tower, pilots in WheelTug equipped aircraft can back away from the gate immediately instead of waiting for the tug to arrive. Standard tug pushback first requires the hook-up of the tow bar to the front landing gear, then the push, and then engine warm up. A WheelTug equipped B737 can save 120–150 seconds during pushback by changing the standard pushback process and transferring engine warm up from 'after the pushback' to 'prior to' entering the runway for takeoff.
The Air Transport Association
(ATA) calculated and reported the "Annual and Per Minute Cost of Delays to U.S. Airlines" as $38/hour/passenger and while Dr. Andrew Cook and Graham Tanner calculated 0.36 Euros (2008).
Studies on FOD have broken the per flight cost of into both ""direct" and "indirect" costs. The per flight direct cost of FOD is calculated at $26 by considering engine maintenance spending, tire replacements, and aircraft body damage. The per flight indirect cost of FOD includes a total of 31 individual categories, and when added, then the cost of FOD increases by a multiple of up to 10x.
As tire changes involve removing the wheel, then depending upon the economic model used (WheelTug sale or lease), the WheelTug wheel can either be rated for the FAA minimum wheel mileage rating requirement or produced as a 'high end' wheel. If produced at the minimum rating, then its replacement cost can be folded into the cost of the lease.
http://www.youtube.com/watch?v=0Cbfi2wsgns http://www.boeing.com/news/releases/2005/q3/nr_050801a.html
Dynetic Systems, Inc. to become responsible for designing the Chorus motors for WheelTug’s electric nose-wheel drive system for aircraft.
http://www.aviationweek.com/aw/blogs/mro/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=388668c6-b459-4ea7-941e-a0a2206d415f&plckPostId=Blog%3A388668c6-b459-4ea7-941e-a0a2206d415fPost%3A5360e953-390f-40f0-9d12-9d47b5f9eeb5&plckScript=blogScript&plckElementId=blogDest
Endeavor Analysis to provide structural and strength analysis work for the landing gear connected to the WheelTug system. http://www.endeavoranalysis.com/
ICE Corporation to design, develop and build the controllers for the aircraft on-ground electric drive system being developed by WheelTug plc.http://www.ice-ks.com/home/pressrelease.htm
Newport Aeronautical Development, Inc. to assist it in meeting FAA standards for a supplemental type certificate covering Boeing 737-600, -700, -800 and -900 aircraft.http://www.flightglobal.com/articles/2007/09/17/216773/wheeltug-eyes-09-certification-of-electric-wheel-drive-for.html
Prague Airport to actively assist WheelTug with the development support during testing and certification.http://www.prg.aero/cs/site/aero_newsletter/aero_2010_07.htm
Resource Group to develop software for WheelTug and to become a significant shareholder. http://www.resourcegroup.co.uk/AboutUs/PressReleases/ResourceGroupjoinsWheelTug/tabid/738/language/en-GB/Default.aspx
Travel Service Airline to provide access to aircraft in connection with the design, development and testing of the WheelTug system. http://www.groundsupportworldwide.com/web/online//Travel-Service-Airline-to-Support-Development-of-WheelTugR-Electric-Aircraft-Drive-System/6$4817
Ground propulsion
Ground propulsion is a different term than transport, because it refers to solid bodies being propelled. Those bodies may be mounted on vats or using wheels while the latter dominates for standard applications....
system for aircraft which puts a high torque electric motor into the hub of the nose wheel to allow for backwards movement without the use of pushback tugs and to allow for forward movement without using the aircraft's engines. WheelTug will drive the aircraft with power supplied by the onboard APU (Auxiliary Power Unit). The first version is being designed for the Boeing 737NG with delivery expected in 2012.
Safety
Two of the main risk sources for accidents and injuries at the gate are pushback errors and engine intake/blast.Pushback
Pushback
In aviation, pushback is an airport procedure during which an aircraft is pushed backwards away from an airport gate by external power. Pushbacks are carried out by special, low-profile vehicles called pushback tractors or tugs....
errors can damage the aircraft and the pushback tug http://www.flightglobal.com/articles/2010/09/11/347208/video-delta-747-shunts-tow-tractor-at-gate.html or can injure or kill the tug operator. Collisions with the tug can take aircraft out of operation for days and have a cascading effect that adversely affects the flight and passenger schedules for the rest of the day, while smaller accidents include tow bar hookup where the tug operator risks injury to the hands.
Jet Blast
Jet blast
Jet blast is the phenomenon of rapid air movement produced by the jet engines of aircraft, particularly on or before takeoff.A large jet-engined aircraft can produce winds of up to 100 mph up to 200 feet behind it at 40% maximum rated power...
behind the engines and the area in front of the engines (Intake Danger Zone) are eliminated in the gate area. When no physical gate exists and passengers disembark onto the open tarmac, then with certain aircraft configurations it is normally necessary to let the engines cool down before a hatch is opened to disembark passengers.
As many of the risk factors (tug collisions, jet blast, jet intake) will be eliminated, it is expected that WheelTug equipped aircraft will have reduced insurance premiums.
Start Times
Many airports have some form of engine noise curfew. If a 6:15AM noise curfew is in effect, a WheelTug equipped aircraft will be able to back itself out of the gate and then queue up for the runway, warming up their engines for at 6:15AM for immediate takeoff.Upon receiving clearance from the tower, pilots in WheelTug equipped aircraft can back away from the gate immediately instead of waiting for the tug to arrive. Standard tug pushback first requires the hook-up of the tow bar to the front landing gear, then the push, and then engine warm up. A WheelTug equipped B737 can save 120–150 seconds during pushback by changing the standard pushback process and transferring engine warm up from 'after the pushback' to 'prior to' entering the runway for takeoff.
Fuel Taxi Margin
Presently, aircraft taxi by using one or more of the main engines, and therefore need to carry the fuel for taxi both to and from the runway, plus an extra amount for either expected or unexpected delays. Additional extra fuel is often carried 'just in case,' or in cases where there is a known or expected delay, and this can add several hundred pounds of weight to the plane and to its takeoff weight. With WheelTug eliminating the engines fuel consumption during all but the preflight warm-up and post flight cool-down period, the needed taxi fuel margin is reduced to just the fuel needed for APU operation.Time Savings
In May 2004, a Performance Review Commission report prepared by the University of Westminster put the cost of 'long' delays (of over 15 minutes) weighted by aircraft types and the known distribution at 72 Euros.The Air Transport Association
Air Transport Association
Airlines for America , formerly known as Air Transport Association of America, Inc. , is America's oldest and largest airline trade association. A4A member airlines and their affiliates transport more than 90 percent of U.S. airline passenger and cargo traffic. Based in Washington, D.C., the...
(ATA) calculated and reported the "Annual and Per Minute Cost of Delays to U.S. Airlines" as $38/hour/passenger and while Dr. Andrew Cook and Graham Tanner calculated 0.36 Euros (2008).
Environmental Impact
CO2 emissions are reduced from both the aircraft's engines and the pushback tug's engines, to only the onboard APU. With only the APU being used to power the aircraft's taxi to and from the runway, engines will be not be generating noise until the warm up period begins before takeoff or the cool down period ends after landing.F.O.D. (Foreign Object Damage)
Engines suck in not only what is directly in front of them, but also items blown in from natural (wind) or unnatural (other aircraft) sources. WheelTug reduces the amount of FOD caused to the engines by limiting their operating times to only the 'warm up' and 'cool down' period.Studies on FOD have broken the per flight cost of into both ""direct" and "indirect" costs. The per flight direct cost of FOD is calculated at $26 by considering engine maintenance spending, tire replacements, and aircraft body damage. The per flight indirect cost of FOD includes a total of 31 individual categories, and when added, then the cost of FOD increases by a multiple of up to 10x.
Brakes
Since standard aircraft taxi is controlled by playing the engines against the brakes, WheelTug will eliminate a significant amount of brake wear as the in-wheel motor will control movement and acceleration. Replacing brakes will become less frequent.Engines
Engine maintenance is partially dependent upon the total numbers of hours the engine operates. For taxi times of 23 minutes on each end of the flight, with multiple flights in a single day, a Boeing 737NG equipped with a WheelTug can save hours of engine operation time and reduce the frequency of the plane being taken out of service. Another factor that affects engine maintenance is the Foreign Object Damage (FOD) to the engines which creates nicks and dings on the turbine blades. To remove nicks and dings, and to return the blades to a more aerodynamically efficient shape, the blades are 'blended;' however the blending process does not return them to their optimal shape, and therefore engine efficiency decreases. WheelTug's reduction of FOD will slow the degradation of engines efficiency over time .Landing Gear and Aircraft Frame
As a standard pushback tug has its own inertia (separate from the aircraft), pushback tugs impart a shock to the landing gear as the tug and tow bar move with their own inertia before the aircraft moves. As WheelTug's motor is inside the wheel hub of the landing gear itself, all starts are smooth and there is no shock to the landing gear or airframe.WheelTug Design
A thumbwheel or rocker type switch in the cockpit will allow for simple operation by the pilot. The inverter/controller in the electronics bay will be independent of the rest of the planes command and control system, and will log position with a GPS module and record other operational information to provide the aircraft owner with additional data for analysis. The motor and gearing will fit within the wheelhub and WheelTug Plc has said its engineers have now designed a solution that also achieves five key design requirements:http://www.wheeltug.gi/Packaging%20Release3May10.pdf- Do not increase the wheel/tire assembly spin-up loads during landing.
- Avoid changes to existing landing gear major components, such as the piston/axle assembly.
- Enable aircraft tire changes as quickly and as easily as is done currently.
- Prevent inadvertent engagement. Unless the aircraft is on the ground, and the pilot has explicitly powered-up the WheelTug system, the motors must not engage with the wheels.
- Match the motor and wheel speeds before engagement, to eliminate the need for a clutch.
As tire changes involve removing the wheel, then depending upon the economic model used (WheelTug sale or lease), the WheelTug wheel can either be rated for the FAA minimum wheel mileage rating requirement or produced as a 'high end' wheel. If produced at the minimum rating, then its replacement cost can be folded into the cost of the lease.
Proof of Concept Test
Boeing Phantom Works and Chorus Motors test WheelTug Concept on an Air Canada 767 in June 2005 at the Evergreen Air Center at Pinal Air Park in Marana, Arizona.http://www.youtube.com/watch?v=0Cbfi2wsgns http://www.boeing.com/news/releases/2005/q3/nr_050801a.html
Electric Load Measurement
WheelTug Limited and Co-Operative Industries complete an Electrical Load Measurement (ELM) on a B737NG in January 2010 at Hartsfield-Jackson International Airport in Atlanta, GA to confirm sufficient power. http://www.wheeltug.gi/press/pr_WT20100201.shtmlData Gathering Tests in Prague
Tests were conducted at Prague Airport in November 2010 in snowy and icy conditions. http://www.youtube.com/watch?v=tTsdpaXUi1Y http://www.youtube.com/watch?v=jt-f8wb5RywPartnering Companies
Co-Operative Industries Aerospace to develop and supply the wire harness for the Boeing 737NG for WheelTug. http://www.coopind.com/news_WheelTugPR.htmDynetic Systems, Inc. to become responsible for designing the Chorus motors for WheelTug’s electric nose-wheel drive system for aircraft.
http://www.aviationweek.com/aw/blogs/mro/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=388668c6-b459-4ea7-941e-a0a2206d415f&plckPostId=Blog%3A388668c6-b459-4ea7-941e-a0a2206d415fPost%3A5360e953-390f-40f0-9d12-9d47b5f9eeb5&plckScript=blogScript&plckElementId=blogDest
Endeavor Analysis to provide structural and strength analysis work for the landing gear connected to the WheelTug system. http://www.endeavoranalysis.com/
ICE Corporation to design, develop and build the controllers for the aircraft on-ground electric drive system being developed by WheelTug plc.http://www.ice-ks.com/home/pressrelease.htm
Newport Aeronautical Development, Inc. to assist it in meeting FAA standards for a supplemental type certificate covering Boeing 737-600, -700, -800 and -900 aircraft.http://www.flightglobal.com/articles/2007/09/17/216773/wheeltug-eyes-09-certification-of-electric-wheel-drive-for.html
Prague Airport to actively assist WheelTug with the development support during testing and certification.http://www.prg.aero/cs/site/aero_newsletter/aero_2010_07.htm
Resource Group to develop software for WheelTug and to become a significant shareholder. http://www.resourcegroup.co.uk/AboutUs/PressReleases/ResourceGroupjoinsWheelTug/tabid/738/language/en-GB/Default.aspx
Travel Service Airline to provide access to aircraft in connection with the design, development and testing of the WheelTug system. http://www.groundsupportworldwide.com/web/online//Travel-Service-Airline-to-Support-Development-of-WheelTugR-Electric-Aircraft-Drive-System/6$4817