The Bloodhound Project The lower rear chassis story

The lower rear chassis story

Engineering News
Wednesday, 12 June, 2013

Engineering and Product Sponsorship Lead Conor La Grue reports on the build of BLOODHOUND's rear lower chassis:

It has been an incredibly exciting period for all the team as the rear lower chassis has been completed. This was the culmination of 30 months of effort by a huge number of individuals and companies and I have to start by saying - thanks Team!  The build of BLOODHOUND SSC is utterly dependent on the huge value brought by our Product Sponsors that are helping bring this car to life.

The lower chassis build story starts in November 2010: We had established a new partnership with Hampson BHW Wigan and explored the resources and manufacturing methods they had to offer us. This gave the Design Engineers a steer the in finalising the detailed design phase of the lower and upper chassis.  Lead Design Engineer Brian Coombs had the first parts detailed ready for manufacture in January of 2011.  Hampson were to manufacture all machinings, large fabrications and final assembly, supported by a syndicate of Product Sponsor companies; Jaivel would be doing the programming for the cutting machines; thyssenkrupp Materials providing the material: steel, titanium and aluminium; Manufax Nelson would be designing, manufacturing and commissioning the assembly fixture, with support from TATA UK for the steel. AMADA would be laser cutting and folding the panels to shape and pilot drilling holes where required. WESCO AIR would be providing support for rivets; DC Electronics would be fabricating the 2.2 km wiring loom with support from Servo Interconnect and Deutsch for the electrical interconnectors. Finally, Goodridge (Flexible) and Swagelock Bristol (Solid line) would be providing the fluid and gas interconnectors.

This list illustrates not just the complexity of BLOODHOUND SSC but how we are so fortunate to be able to call on the diverse expertise of so many partners – all dedicated to helping us create this Engineering Adventure.

The first drawings being handed over to the Hampson team Feb 2011 – promotional event at BHW Wigan.

The first parts manufactured by the lower chassis syndicate June 2011 (Ian Gaskin and Richard Noble)

There are 77 major parts in the lower chassis, machining and fabrications in Titanium, Steel and Aluminium, and that all had to be designed and manufactured before we could look to start final assembly. By June 2011 the first parts had been programmed, material delivered and machined parts were starting to arrive.  Brian was working his way through a huge design package and we were spending an increasing amount of time on the M6 travelling from Bristol to Wigan!

Once there was sufficient design work done to lock in the major fixture points, Brian was able to release detailed drawings to Manufax Nelson so they could start making the  Main Fixture (the fixture is what the chassis will be built on: a large, rigid and absolutely flat slab of steel which  keeps the hundreds of components in place before they are glued and riveted together). Manufax Nelson pulled out all the stops to get the lower fixture designed,  manufactured,  assembled and commissioned before the Christmas break 2011 – top job guys!

23rd December 2011 - Fixture gets delivered to BHW wigan -  just in time for Christmas 2011 !

23rd December 2011 - Manufax Nelson team set up the fixture at BHW Wigan Christmas 2011

Feb 2012 - First laser cut parts from AMADA towards the lower chassis

Amada in Kidderminster were able to speed up some of the production of fabrications by cutting and folding some of the steel and titanium parts at their amazing showroom facility. The team there worked through a long list of steel parts, using state of the art laser cutters to make one-off components, saving the Project many hundreds of hours compared to doing the same jobs by hand.

March 2012 - One of the last very large machinings being completed at the BHW Wigan site.

Very large components not only take a long time to design. In some cases, new tools then have to be created in order to manufacture them. For the car’s large floor section - a new plate had to be designed and commissioned to expand the capability of the cutting machine before we could even start to make the part. Many hundreds of hours of spindle time (the time when the cutting head is whizzing around) go into making these one-off parts, which have to be right first time. The cost of material is a huge proportion of the overall cost and in this case we were hugely lucky to have thyssenkrupp Materials provide all the material on a fully sponsored basis.

April 2012 - Sills sections being TIG welded by the BHW Wigan team.

March 2012 – Richard looks through the completed fabricated lower chassis components.

May 2012 – Parts offered up onto the assembly fixture for the first time.

It was May 2012 by the time we had sufficient parts completed that we could start to mount them on the fixture. The rear lower chassis component designs were completed and it was now a question of getting parts programmed into the cutting machines and manufactured by BHW Wigan as fast as possible.

By the August 2012 we were nearly there with all the component parts.  Brian and I travelled up our familiar M6 groove to BHW Wigan and completed a pre assembly review: checking that the chassis was ready to go together, working out the sequence of events and getting the components 100% clean so that the assembly work could begin.

Pre assembly review August 2012 – large machinings now completed.

The commercial position of Hampson BHW Wigan had changed by this stage and we were struggling to get the assembly resource in working hours. Many of our Hampson team had left the company and we were progressing the build as best we could remotely. The remaining Hampson volunteer workforce put in a huge amount of their own time after hours (Thanks again folks).

October 2012 - we had started pre assembly but progress was frustrated by the trading position of Hampson BHW Wigan.

On the 14th of November 2012 we had to take the step to remove the chassis and fixture from BHW Wigan;  the company was about to change hands and although all concerned were working to continue the relationship after the sale we just couldn’t risk the parts and fixture being held up in any way.

Huge thanks to all the external organisations and individuals that worked so hard and so long to deliver this next large chunk of car. The lower chassis is at the heart of all the integration of all the main systems.

The chassis and fixture being picked up and bought to the BLOODHOUND Technical Centre for completion of the build – the sale of BHW Wigan was completed just a few days later.

Fixture in place at BTC 1 -  Feb 2013 - assembly work at an advanced stage

With 77 major parts and 3,500 rivet holes to align, drill off, countersink and a process involving repeated build up and strip down and a complete removal of all parts for anodising and coating with a lightweight paint called Kephos, the final assembly of the lower chassis has been a huge and complex task.  We also made the decision reasonable late on to run the wiring loom and the hydraulic pipes for airbrakes and wheel brakes through the sill sections -  something we hadn’t planned on doing back in January 2011 when Brian released the first D nose sections for the sills. Chris Dee our Chief Mechanic and his highly skilled fabricators and mechanics notably Marco, Viv, Tufty and Lee have done a great job of putting the lower chassis together.

23rd April 2013 - The loom installed - thanks to DC Electronics and Servo Interconnect – also thanks to Swagelock Bristol for the hard line installation (and the late nights!)

You can see here how busy things are inside the sills - amazing reserve of flexibility in the overall design by Brian as when the D nose sill sections were drawn no services were going through the sills at all.

DC Electronics had done a great job fabricating the loom in short order and Swagelock Bristol were kind enough to work late over a number of days to keep us on schedule to do the final bonding cure at National Composites Centre. – Thanks team.

3rd May 2013. Last outer panel goes onto the lower chassis, mechanics Viv and Marco in shot

3rd May 2013 - Brian gets to pull the trigger on the last rivet of the lower chassis – number 3,500!

7th May 2013 - The lower chassis goes for cure at National Composites Centre.

After much analysis and a number of dead ends and U turns we had a final route for bonding material for the lower chassis; we now needed a very accurate oven to do an eight hour cure at 85 degrees centigrade (185 deg Fahrenheit) – one big enough to take the lower chassis and its fixture all in one go.  We discovered that the team at the National Composite Centre NCC at the Bristol and Bath Science Park had a huge autocalve (a high pressure oven) used for the development of complex carbon structures and aircraft wing sections that was absolutely ideal for our needs.

Tim Frost our main contact there was fantastic , making sure the dates critical for glue life could be met. The glue we used has to be kept in a freezer to keep it ‘fresh’. Once out of the freezer we had 30 days to assemble the entire chassis and cure the glue before it went ‘off’. The cure was a success. See the technical article Lower Chassis Adhesive Testing by Chris Hannon for the full gluing story.

7th May 2013 - Final checks inside the autoclave before cure begins

We fixed seven thermocouples over the length of the chassis to ensure we could monitor and control temperature in the three heating and cooling zones within the autoclave. To give you an idea of how large it is, the door alone weighs 13 tonnes!

7th May 2013 - Just as well it was this big – chassis fills the autoclave at National Composites Centre

8th May 2013 - Drawbridge going down at NCC large autoclave – first view of the cured chassis – all looked good!

8th May 2013 - First view – NCC Tim and Brian check out the cured lower chassis – great job by all involved.

9th May 2013 - Roland Dennison (AKA Head of Worry!) Inspects the now baked and turned over lower chassis

The picture left shows the chassis right way up and sat on its cups and cones on the surface table in our new, much larger workshop: 30 months of intense design, manufacture and assembly completed. In many ways the lower rear chassis is the heart of BLOODHOUND SSC. So many of the major systems are populated into this section, including the hybrid rocket, Cosworth F1 engine and their systems, which is why it was one of the first areas to go through the detailed final design and build process. It is a complex piece of engineering, using a raft of different materials, some mundane, some exotic, created with the help of an extended team spread across twelve different companies working over two years.

The hard won lessons we have learnt on designing, manufacturing and assembling the lower chassis have already fed into the design manufacture and build of the rest of the car.

To all those individuals and companies involved in the lower chassis build – “thanks team – great job!”