As part of Guy Martin’s latest television series, JCB once again returned to Elvington Airfield, Yorkshire to set a new speed record with a Fastrac tractor. James Rickard was there to witness it.
Aiming to top its previous British speed record achievement of 103.6mph, as reported by Farmers Guardian back in June, JCB and Guy Martin were on a mission to set a new world record.
And with an official record speed of 135.191mph, and a top speed of 153.771mph, it was celebrations all round for the Staffordshire-based outfit.
As before, the record achieved is an average taken over a one kilometre distance. This kilometre run also has to be done in two different directions, within an hour, to count.
However, as we found last time, this is no normal Fastrac tractor. In the eyes of Guinness World Record, it is classed as a ‘modified’ tractor, which when you get under the panels, the term hardly does the level of engineering work justice. These levels were also raised for this second attempt, with a second tractor built using the knowledge learned from the first time (see panel).
Tim Burnhope, JCB chief innovation officer says; “For us it is about showcasing the best of British design and engineering.
“With an average age of 27, we have had a fantastic young team working on this, who have been allowed to really push the boundaries of what is possible, and in this respect they are fearless.”
As mentioned, for this second record attempt, JCB took what they learnt from the first time round and incorporated that knowledge into a second tractor.
Alan Tolley, JCB group director of powertrains explains; "In particular, aerodynamics were a massive learning curve for us. As you can image, this is not something which we normally need to worry about with our products.
“In addition, we really had to up the power levels, while at the same time reduce weight. As a result, it was more sensible to build a second tractor, rather than try and adapt the first one.”
Following the first attempt, the manufacturer soon realised that structurally, the second Fastrac could be made lighter. In particular, the chassis alone could be made 22 per cent lighter – one of the main reasons for a second tractor to be built.
Bonnet and brackets were also changed to aluminium from steel. Overall, Fastrac 2 is 10 per cent lighter than Fastrac 1. This equates to about 500kg, resulting in a machine weight of just under five tonnes.
Helping refine airflow around the tractor, JCB called upon the expert services of famous ex-Formula 1 race engineer Rob Smedley. Formerly of Ferrari and Williams, he and Williams Advanced Engineering created air flow maps (computational fluid dynamics) to find areas of improvement.
This saw rear side wings fitted behind the cab to prevent turbulence, a rear cover to smooth out airflow over components, redesigned side pods and the inclusion of an under tray to better channel air around the tractor, and the addition of engine side panels.
Another major area was the cab roof lip which surrounds the work lights. Mr Tolley says; “This area alone created an enormous amount of turbulence and ‘air disconnect’ from the tractor’s surfaces.”
As a result, the work lights and lip were removed to create a much cleaner edge around the top of the tractor. In all, total drag was reduced by 10 per cent.
Though capable of 1,000hp, for the first attempt the six-cylinder, 7.2-litre JCB DieselMax engine was only running at about half power. In comparison, for the second attempt, substantially more power was unleashed.
Working with engine expert Ricardo, 1,016hp at 3,150rpm was extracted from the diesel-powered engine during practice. To achieve this, several modifications were made including a revised exhaust manifold to improve flow.
To keep up boost pressure in the turbo charger and prevent ‘lag’ between gear changes, it was injected with 300psi of high air pressure and a dose of water. The latter expands when it comes in contact with the hot manifold, and provides a ‘filler’ gas in the absence of exhaust gas, which momentarily prevents the charger from slowing down.
Cooling was also a major challenge. For Fastrac 2, the charge air cooling system was aided by the use of an ice tank, which reduced air temperature by another 50 degrees. However, this meant for every run down the runway, the tractor needed topping up with ice.
Though the tractor used the same six-speed gearbox as last time, this time the tractor had the power to get into fifth gear.
Via a multi-plate wet clutch, spikes of torsional stress along the driveline were also reduced. And a lot of high speed testing was done on a rig to determine the limits of the tractor’s BKT Ridemax tyres.
Brakes were still the Fastrac’s standard disc brakes, which were more than capable of bringing the much lightened tractor to a halt. For visual effect, these were accompanied by a parachute.
Suitably attired in work boots, the tractor was once again piloted by speed daemon Guy Martin. He says; “You knew you were going fast this time. There were a couple of moments when it got wet where the back-end got a bit lively.
“Between this one and the last tractor, there is definitely more urgency about it.
“I don’t think there is much more speed left in it, though. At 153mph it was just about in its steady state where acceleration levelled out.”