• Cooling Challenges For The Bloodhound SSC’s Engine

With 1,000 liters of High Test Peroxide onboard to power its rocket engine, the 1,000-mph, 2014 Bloodhound SSC could become a bomb if temperatures within its tightly packed fuselage get too high. Each liter of HTP has roughly the same explosive force as a stick of dynamite when it starts to decompose at 40°C (just 104°F). That means cooling the system is not only hugely important, but also massively challenging, when you consider that ambient temperatures routinely hit 100°F at the Hakseen Pan in South Africa where the Bloodhound SSC’s initial trials will begin. The fact that the supercharged Jaguar V-8 — which pumps 900 liters of HTP to the engine in just 20 seconds — is situated right next to the HTP tank further complicates matters. Oh, and temperatures inside the hybrid rocket engine will hit 3,000°C.

To solve the heat problems, Bloodhound SSC engineers have sourced some innovative insulating coatings from a company called Zircotec. The Jaguar exhaust has been coated with a substance called Thermohold, which is plasma sprayed on to surfaces at twice the speed of sound (Did they hear a bunch of tiny sonic booms?), and reduces surface temperatures by 30 percent.

In the past, most land-speed-record car bodies have been made of steel or aluminum instead of carbon fiber, which melts at much lower temperatures, but that’s not the case with Bloodhound SSC. To prevent both its jet and rocket engine from turning it into a steaming puddle of plastic, its carbon body panels have been coated with Thermohold for Composites, which is sprayed on at 10,000°C (about 18,000°F) in a way that doesn’t damage the panels and lowers temperatures by about 100°C (over 200°F). Zircotec has also supplied special heat shields, called Zircoflex, which are flexible, adhesive panels just 0.3 mm thick and can withstand temperatures up to 500°C.

Continue reading for the full story.

Why it matters

The numbers and forces that will be at work within Bloodhound SSC are truly amazing. Between its EJ 200 jet engine and hybrid rocket engine, it will produce 135,000 horsepower. It should only take 55 seconds to get to 1,000 mph, at which point it will be pushing against 20 tons of drag. If you fired it straight into the air, it would go 25,000 ft. into the atmosphere, and its aluminum wheels have to withstand 50,000 Gs at their rims.

Initial construction is expected to wrap up later this year in Bristol, England, after which current land-speed record-holder and former Royal Air Force pilot, Andy Green, will begin putting it through its paces in South Africa. Speeds will gradually ramp up from there, with the final 1,000 mph run slated for sometime in 2017.
Stay tuned!

2014 Bloodhound SSC

2014 Bloodhound SSC High Resolution Exterior
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Read our full review here.

James Wolfcale
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Press Release

Cooling a 135,000bhp, 1000mph car poses critical challenges for safety and performance that now, just six months ahead of the first run, the Bloodhound team is looking to solve

As the build of Bloodhound SSC gains momentum and a planned UK test in Newquay is just months away, engineers are increasingly looking at the detail design challenges to help them push the car to 1000mph and above. These include the issues of cooling the tightly-packaged Rocket engine together with ensuring the volatile HTP (High Test Peroxide) doesn’t decompose before it reaches the rocket chamber and in effect, become a bomb.

“We’ve got approximately 1000 litres of HTP that has the equivalent explosive force of 1 stick of dynamite per litre if it reaches 40°C, and starts to decompose” says Tony Parraman, of the sponsorship liaison team. “Packaging dictates that our supercharged Jaguar engine, that we use to pump 900 litres in just 20 seconds, is sat next to the tank so preventing heat transfer is on our essential list.”

As a prime source of heat in proximity to the tank, the Bloodhound SSC team specified Zircotec’s ThermoHold® ceramic coating for the Jaguar exhaust. Plasma-sprayed at twice the speed of sound itself, the coating can reduce surface temperatures by at least 30 percent, ensuring even as heat builds up during the two runs needed for the record to be validated, the tank remains stable.

Cooling Challenges For The Bloodhound SSC's Engine High Resolution Exterior Press Releases
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Unlike previous record challenging cars, a large proportion of the Bloodhound front structure is composite. Chosen for its excellent strength/weight ratio, the drawback of composites is its poor resistance to temperature compared to metallic options. “We turned to Zircotec again,” adds Parraman. “We know that they have supplied heat resistant coatings to F1 teams for years, literally preventing the delamination of carbon fibre in high temperature environments, enabling the material to be used above its traditional melting point.” Zircotec proposed ThermoHold® for Composites, a zirconia-based coating that is applied at temperatures exceeding 10,000°C but in such a way that the substrate is unaffected. “Zircotec’s patented technology for protecting composites offers a huge benefit, allowing the use of lightweight materials in places where they are exposed to significant heat. Our engineers are not experts in thermal management and having Zircotec’s technical support is helping to ensure we only use the coating where it is needed, saving weight where we can,” adds Parraman. “We have used the coating on the composite upper chassis hoop, offering lightweight resistance that lowers surface temperatures by 100°C.”

Digging deeper into the Zircotec parts bin has seen Bloodhound pick ZircoFlex®. The proven hybrid aluminium/ceramic heatshield, just 0.3mm thick, is being applied around any areas of the vehicle where heat is expected and needs to be resisted. “With ZircoFlex® we can bend and mould it to shape, it’s lightweight and with self-adhesive backing, good for up to 500°C, we can use in lots of areas,” claims Parraman. “For example after a two minute run, the internal temp of the jet or rocket might be 3000°C but the externals are 200°C. We can manage that heat with ZircoFlex®, protecting wiring looms and composite panels.”

With ambient temperatures of 40°C expected in the South African desert, Zircotec is being relied upon to keep temperatures down during the critical time slot of one hour between the two runs. “We’ve got 60 minutes to turn the car ‘around,” adds Parraman. “We want to prevent heat soak during this time. It will help us work faster without the risk of getting burnt and if we need to change the rocket, it should speed up changeover time.”

The team will trial the car in South Africa, providing a real test of the thermal protection. “We plan to thermocouple the car and see where the heat issues are,” suggests Parraman. “It’s a one-off and we are pushing the boundaries so we don’t know all the answers. Once we do, we’ll be working with Zircotec to ensure that when we do get to Hakseen Pan in South Africa we are fully prepared to deal with the heat.”

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