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A winning Formula


by Ian Homer. Posted to category: Education

Part Two

                Did you miss Part 1? Read that here:

Trustee Steve Liddle continues his story of what was to become a career in aerodynamics ...

Back to Barton though and the world of aerodynamic research. A hot topic from the 1990s onwards was the field of active flow control, in which some attempt is made to use powered systems to change the overall flow around parts of an aircraft. This might be to increase lift in a condition where the flow would normally be separated for example, or to provide greater controleffectiveness than would normally be available.

At Manchester, we were working on a device called a synthetic jet actuator (SJA), which was electrically powered and created a vortex over a surface in a flow, increasing mixing and delaying separation. Many aircraft have small fin-like vortex generators mounted on their wings for this purpose, but the advantage of the SJA was that apart from a small hole in the surface, it was invisible to the flow when not required, so produced no unnecessary drag in the cruise – efficiency is of course key both economically and in our environmentally minded world. A disadvantage with working with them though was their piecing 2kHz shrieking, which became distinctly unpleasant after a day in the control room.

Airbus were keen on applying these devices to future aircraft which happily provided both context and funding, so a for a few years I was able to do my bit to make the airliners of the future greener while (in addition to hours of testing) attending meetings and conferences around the world and gaining a PhD.

It hadn’t really occurred to me that such jobs existed when I was growing up. If the main USA aerodynamics conference was in the Sierra Nevada in the ski season or it was useful background to visit the A380 Final Assembly Line in Toulouse, who was I to argue?

Civil aircraft were one thing, but another strand of our flow control research looked at making the military aircraft of the future more manoeuvrable without changing their external shape; they could be ‘flapless’. This was part of a BAE Systems programme called FLAVIIR, which aimed to build a small demonstrator aircraft (eventually called DemoN) in conjunction with several universities and technology companies. DemoN’s initial construction took place at the BAE Systems training centre in Preston, involving their apprentices and close to where a small team had designed the Canberra over sixty years earlier.

 

DemoN on display at Farnborough 2012 . Right: On a test flight (Author's collection).

Manchester had what I thought of as the really interesting bit, the aerodynamic control devices. On the wings, air blown over curved trailing edge could alter the lift differentially to give roll control, or symmetrically for high lift. The engine nozzle also feature curved surfaces and auxiliary blowing that could vector the exhaust flow (like water from a tap flowing over the back of a spoon, the Coanda effect), giving high authority pitch control. To prove these techniques, as series of small radio controlled aircraft were built, which culminated in JAVA, an aircraft with a shape reminiscent of the X-45 UCAV demonstrator (and painted black, obviously). This was powered by a model jet engine, which we modified to provide the necessary bleed air for the active controls. One benefit of being a university was that we have a University Air Squadron, based about an hour away at RAF Woodvale. They helpfully organised for us to use their airfield, so that on a very cold day in February 2010, JAVA flew circuits with its pitch control provided entirely by its engine and nozzle. Not believing such a thing to have been done previously, we were quite pleased with ourselves.

You can see JAVA and its Fludic Thrust Vectoring nozzle on display today in the Manchester Museum of Science and Industry, where years before I had seen the windtunnel models built by earlier generations of engineers for outstanding Manchester produced aircraft.

 

JAVA preparing for flight and on display in the Manchester Museum of Science and Industry. (Author's collection and (C) MOSI.) 

Eventually though, you need a proper job and some years after I should have thought about this, I found myself heading down an alternative aerodynamic path into Formula 1. I joined the aerodynamics department at Red Bull Technology towards the end of 2010. At the time, they were on the cusp of winning their first championships, but the season had been to some extent heavy weather and it was not until the end of last Grand Prix that the eventual winner Sebastian Vettel found himself leading. This was definitely another world in terms of the pace of development; whereas I had been working on ideas for twenty years in the future, the turnaround from idea to application here was measured in weeks or even days.

The technical aspects of Red Bull Racing were (and are still) under the auspices of Adrian Newey, which was a bit like finding yourself working for Reginald Mitchell or Brunel as far as I was concerned. I worked for most of my time there on developing the rear part of the car, which critically in the 2010-13 period included investigating how to make the exhaust add to the downforce produced at the rear axle. In 2009-10, the regulations allowed (perhaps!) a ‘double diffuser’, which in the case of the Red Bull RB6 was augmented by exhaust blowing. For 2011, both the double diffuser and the exhaust position were outlawed, which meant a huge loss of rear downforce.

Adrian’s concept to recover this involved exploiting a small region of the outboard floor where it was possible to position the exhaust, from which it would blow down into the tyre contact patch, protect the diffuser from the aerodynamic losses and load it up due to the high energy in the plume. Very little on track testing of the complete car or indeed its systems is permitted, so despite the promise there was still something of a leap of faith associated with RB7 and its floor mounted exhausts when these were eventually revealed, not of course on day one of the test, when the configuration was more conventional.

Sebastian Vettel in the RB7 racing at Monaco in 2011. CC by 2.0

There were concerns for example that the hot gas would damage the new Pirelli tyres, making the concept unworkable. However, it appeared Red Bull were not alone in generating innovative but practically challenging solutions. Lotus Renault had an exhaust blowing from the front of the sidepod all the way down the floor, meaning it was cooler by the time it reached the rear tyre but would have less effect on the flow there. McLaren’s car had an exhaust that exited through a number of ducts all the way around the tyre. Unfortunately for them, this had problems structurally and could not be made reliable enough, but a few weeks later in Australia for the first race, they had incorporated a solution ‘inspired’ by Red Bull’s. This was a demonstration of development prowess that struck fear into hearts in Milton Keynes!

RB7’s pole position in Australia was a great relief, even more so when it was converted into a win on the Sunday. The car would go on to qualify in P1 in 18 of the 19 races of the season and eventually give both Sebastian and the team second championships. However, had we still been running the Australia spec car at the end of the season, it would have been the fourth quickest at most, hence we would only have been qualifying by rights in P7/P8. Keeping the car at the front required a ferocious effort in terms of aerodynamic development, focussing on the downwashing of the exhaust, a floor and diffuser that could use the potential of the high energy flow and a front end that could balance it.

Next week:  Steve talks more on F1 and of a meeting that would bring an invitation to become a Trustee of the Vulcan to the Sky Trust. Read the article here:

 

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