This month’s cover features Stillam CNC Programming Solutions, the Sub Saharan distributor for Edgecam (which has been used in machining components for Bloodhound SCC world land speed record attempt), Alphacam, Cabinet Vision and Radan sheet metal CAD/CAM software.
It’s an extraordinary time for the world land speed record, with a number of teams aiming to run the world’s fastest car in the next few years. This level of record-breaking activity is very rare – it happened in the 1930s, and again in the1960s, but since then it has been very quiet. Suddenly, we’re entering another ‘golden age’ for the world land speed record.
The current world land speed record stands at 1 227.9 km/h, as set in October 1997 by British Royal Air Force pilot Andy Green driving the jet-powered Thrust SSC. Green is looking to break his own record and has a new team and a new car behind him.
Picture courtesy Curventa and Siemens
The car he plans to use is the Bloodhound SSC, which in addition to a jet engine comes with a rocket-propulsion system that Green hopes will take him to a top speed in excess of 1,600 km/h. The team behind the Bloodhound SSC is predicting a speed of 1,680 km/h!
Getting anywhere close to 1,600 km/h on land will be a monumental achievement. The only other manned vehicles capable of those speeds within earth’s atmosphere are military fighter jets, although none can do this speed close to the ground where the air is thicker.
Fast jets typically take 10 years to design, with a team of several thousand engineers exploiting vast accumulated knowledge and budgets of tens of billions of dollars. Bloodhound has a team of just 60 and only what funds it can acquire through sponsorship.
Testing of the Bloodhound SSC will get underway in the U.K. early next year before the team finally heads to Hakskeen Pan, South Africa in late 2015 for the attempt – where the car can be run on a stretch of desert that’s 3.2 kilometres wide, 19.3 km long, and perfectly flat.
Bloodhound programme director Richard Noble says the supersonic car (SSC) will only start its test runs – some of which may already break the current 1 227.9 km/h land-speed record – at South Africa’s Hakskeen Pan, in the Northern Cape, in the third quarter of 2015, with the big 1 600 km/h run slated for 2016.
South Africa has the biggest and firmest dried-out lake bed in the world in Hakskeen Pan – and it is pretty flat too. To put it in numbers, the total variation in elevation over the two km strip is a mere 61 mm.
Following doubts over whether the car would be ready in 2014 for the start of testing, Noble and his team decided to rather extend the R515 million programme by one year.
It is not simply a question of putting the car on its wheels and gunning for the 1 000-mile-an-hour mark immediately – which will be a 30% improvement on the current record or, to put it in context, faster than the bullet from a .357 Magnum.
Breaking the land-speed record takes months of testing and fine-tuning, a process Noble should be familiar with, as he managed the programme that set up the current record.
The Bloodhound is a jet- and rocket-powered car with a slender body, around 14 m in length, with two front wheels situated within the body and two rear wheels mounted externally within wheel fairings.
It weighs more than seven tons and the engines produce more than 135 000 hp, which is more than six times the power of all the Formula 1 cars on the starting grid put together.
The Bloodhound is a mix of car and aircraft technology, with the front half a carbon-fibre monocoque, similar to a racing car, and the back half a metallic framework with panels like an aircraft.
It is named after Bloodhound aerodynamics chief Ron Ayers’ first missile, the Bristol Bloodhound 2, a surface-to-air missile that would accelerate from standstill to Mach 1 in 2.5 seconds – another impressive number.
The Bloodhound is being assembled at the Bloodhound Technical Centre, in Avonmouth, Bristol, in the UK. The first metal for the manufacturing of components was cut back in 2011.
“It took 55 engineer years of research to get to the detailed design of the car,” says Noble.
“Having moved into our new facility in Bristol, the build is progressing well. The next few months will see the lower structure and monocoque completed and the upper structure being built on the assembly fixture,” adds Bloodhound chief engineer Mark Chapman.
“The car has been designed so that the assembly is modular, and while the main structure is coming together, the suspension and rocket modules can also be worked on.”
Chapman says the biggest challenge in building the car is timing.
“We don’t have the luxury of completing the whole car design before parts are issued for manufacture, so, from now till the car rolls out in 2015, there is a challenge to balance the release of data for the long-lead manufacturing parts, and to keep the build team supplied with all the parts they need just in time to meet the plan.”
There are around 160 companies supplying parts to the Bloodhound project.
The first low-speed runs of the Bloodhound will be on a runway in the UK towards the end of the second quarter of 2015. These runs will be limited to around 350 km/h and “are principally to perform a shakedown of the vehicle systems,” says Chapman.
Following the UK test runs, the car and its immediate support equipment will be shipped by air to Upington, in the Northern Cape. The remainder of the technical camp will have already been shipped by sea, and will be set up on Hakskeen Pan, awaiting the arrival of the car.
Edgecam CNC software involvement
An essential part of the assembly holding the rocket motor in place when the Bloodhound supersonic car travels at over 1,600 km/h during its bid to break the World Land Speed Record in 2016, has been made using Edgecam CNC software.
“The accuracy of Edgecam’s toolpaths was vital in allowing us to achieve the extremely tight tolerances required,” says Andrew Wright, production engineer at the Sheffield-based Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC). The Nuclear AMRC manufactured the rear sub-frame for the car, a large complex assembly, which sits inside the exterior Titanium skin.
Bloodhound also aims to excite young people about manufacturing and engineering. The car is a mix of automotive and aircraft technology, powered by the engine used in the Eurofighter Typhoon aircraft, along with a hybrid rocket.
The body and chassis are relying on a range of advanced design and manufacturing techniques, including a specific production engineering solution with Edgecam that prevented distortion of the rear sub-frame sidewall structural panels. The 1.6 x 1 metre panels were produced by the company on its Starragheckert HEC 1800 large format horizontal boring machine. They have to mate up with other parts in the rear assembly which are vital in keeping the rocket pointing perfectly backwards and providing downward thrust when RAF fighter pilot Andrew Green drives into the history books in South Africa in 2015 and 2016.
While the typical machining tolerance for milling was + or – 0.1 of a millimetre, some of the wall thickness tolerances were + or – 0.05, and hole diameters down to + or – 0.025.
“The original billet of aerospace grade 7075 aluminium was 80 mm thick, and the finished component is 20 mm, with some minimum wall thicknesses just 6 mm. Removing such a large amount of material while maintaining the flatness and shape of the component over that size and envelope of machining, was quite a challenge,” explained Wright.
Couple that to the fact that the billet was only around 30 mm longer and wider than the finished part, and it is easy to see why Andrew Wright’s experience in finding correct production engineering solutions across a variety of projects, was essential.
Picture courtesy Curventa and Siemens
“My main concern when I started programming was that the part would distort and we’d struggle to maintain wall thicknesses. If some of the walls became too thin, the component may not have been strong enough.” But he says Edgecam’s roughing strategy and profiling cycles were perfect for his solution.
“We used a three-side machining strategy of roughing one side out, rotating the component and roughing the opposite side, then we released it and reclamped it to finish machining that side. We turned it back round again to finish the side we’d started cutting originally. That way we minimised distortion and any chance of having the walls too thin.”
“I built the machine setup in a 3D design package and Edgecam allowed me to import this directly into the system. This included the part model originally supplied by Bloodhound in NX format, the modified stock model and all clamps and fixture elements. Edgecam’s ability to read a wide range of model formats and to handle assemblies was invaluable, with multiple setups of the part required.”
“While utilising some 3 + 2 operations, much of the work was 3-axis milling, contour and profile milling, with 4th axis rotation to reach additional features. We set multiple datums, and indexed between those datums all within the same set-up. I built as much of the manufacturing process as possible into the Edgecam part files before taking it to the final simulation.”
“Edgecam tailored the toolpaths exactly to the features we needed to machine, particularly when it came to leaving extra material for clamping. With scant excess material on the length or width of the billet, clamp areas were required which were removed later. The toolpaths were customised around the clamp areas and extra geometry added. Edgecam gave us perfect toolpaths which allowed us to cut very accurate profiles.”
“With the difficult shape of the component and small amount of stock material, Edgecam’s ability to tightly control the link moves and feed in / out moves between sections, enabled us to produce smooth and safe transitions between machined features and areas.”
“For the main machining we kept the cutting tools, all of which were supplied by Sandvik, down to a minimum. As we were looking for a secure and accurate process rather than a high productivity operation I only used three cutting tools to do most of the milling – a solid carbide end mill, a solid carbide ball nose end mill to finish the profiles, and a chamfer mill to deburr as much of the component as possible in the machine, which reduced manual handling.”
“Edgecam’s Code Wizard was another big plus for us, so much so, that we could not have produced the components in the allotted time, without it.”
“As we were using a brand new machine we only had a simulation post processor for its predecessor, the Starrag 1600. But Edgecam made it very easy to create, in effect, a daughter post processor for the new 1800.”
“We created the code using the 1600 post processor, ran a simulation and then re-processed the file for the 1800 with minimal changes. This gave me absolute confidence in the toolpaths going down to the shop floor without having to do too much on machine prove-out, knowing that the X Y G-code wasn’t affected between the two simulations.”
For more information contact Stillam on TEL: 011 663 2600 or visit www.stillam.com