The TaxiBot research vehicle tractor has undergone successful trials with Lufthansa LEOS. Tom Allett reports.
Originally launched two years ago, the TaxiBot tow tractor concept jointly designed by France’s TLD and Israeli Aerospace Industries (IAI) is now nearing production. Rather than using the traditional tow-tractor/driver method of moving aircraft, the TaxiBot system enables pilots to manoeuvre both aircraft and tractor direct from their flight deck.
Early trials, conducted using a test rig vehicle that carried a genuine Boeing 747 cockpit ‘on stilts’, proved successful when operated by current Lufthansa pilots. Subsequently, a research vehicle – looking like a conventional tow tractor, but including the TaxiBot controls – was produced. By this time Airbus had also joined the development consortium and the research vehicle has subsequently completed tests at several locations over the last 18 months or so, including Airbus’ Toulouse factory.
During trials carried out at Frankfurt by Lufthansa LEOS in December 2010 the vehicle handled a Boeing 747-400 for the first time. According to Lufthansa LEOS: “Ice, snow, and Siberian temperatures” had dominated the TaxiBot’s December test-runs but, it added, despite this, “valuable findings” had emerged about TaxiBot’s “realistic deployment on a busy airport”. It said that the “best news” emerging from the December trials was the “perfect functioning of all systems even under severe weather conditions”. Nevertheless, inevitably, a wide range of ‘fine tuning’ adjustments and re-calibrations were required. The engineers were unanimous in their view that the steering was not quite right and decided that its “wiggly steering” was caused by its electronic signal transmission, making the steering “over-sensitive”. The nose gear turning plate was also adjusted and this cut out the risk of jack-knifing; a term used to describe how the tractor could accidentally slide under an aircraft’s fuselage in slippery conditions.
In March these improvements were tested by the research vehicle – attached to the nose wheel undercarriage leg of a Boeing 747-400 – performing several ‘figure eights’. Repeated acceleration and braking tests were also carried out plus a simulated docking at Frankfurt’s Gate B22. These were concluded on March 25 with the consortium of IAI TLD, Airbus and Lufthansa LEOS stating that it was: “profoundly satisfied with the results” and that TLD will build a genuine TaxiBot prototype to replace the present research vehicle: “before the end of this year”. Lufthansa LEOS stated that the “beautiful spring weather had allowed TaxiBot to tow at its maximum speed of almost 30km/h [18mph] for the first time.”
Elmar Boje, Chief Pilot of Lufthansa’s Boeing 747 fleet, was pleased with the TaxiBot method, saying: “The system already now reaches over 90% compatibility with traditional piloting under [an aircraft’s] own thrust.”
Many visitors, including some travelling from as far as the US and Japan, witnessed the tests, and Andreas Roesler, General Manager of Lufthansa LEOS, said: “With so many critical experts being so enthused, quite likely we have witnessed environment-friendly aircraft towing of the future”.
The author would like to thank LEOS’ Project Engineer Bernhard Weiss for providing much of the information.