Bloodhound SSC

[Skylon]

It has been announced that the British-made Bloodhound Supersonic Car will undergo a low speed run at an airport in Cornwall in October. I'm guessing most of you know what this is, but it's a car that should be able to go at 1000mph and will break the land speed world record (only going to 800mph, previously held by Thrust SSC, piloted by he same man who holds the record, Andy Green. Here is the update from their website. 

 

[shynung]

Fun fact: a Jaguar supercharged V8 engine is used to power the oxidizer fuel pump for the Bloodhound's hybrid rocket.

[p1t1o]

FunFact #2: Its jet engine is an EJ200 that otherwise would be powering an RAF Typhoon.

***

Honestly, Im of the opinion that "land" speed records are pretty moot now. The challenge is no longer getting the vehicle up to speed, the challenge is keeping it rolling along the ground, and at this point, doing that is so much more difficult that it is more of a "land robustness record" than anything else. Its the wheels that are the engineering marvel in machines like this, the engines are just off-the-shelf tech. The last SSC used engines from an F-4 phantom -  a jet which first flew in 1958! (though Im guessing the engines were uprated since the first year of service)

Its basically a "quite fast but not groundbreaking" aircraft being flown really badly. Or really brilliantly, depending on how you look at it.

But i cant in any way see these vehicles as "land based" any more than if you rolled an ocean liner along the motorway on a set of logs.

Literally all you have to do is add some control surfaces and its now a quite-fast plane that wont break any records. Maybe it would have a shot at some time-to-height records? I dunno.

Heck, the danged thing probably already has control surfaces, I wonder if you couldnt just steer it upwards.

Edited June 13, 2017 by p1t1o
something something wheels

[magnemoe]

1 hour ago, shynung said:

Fun fact: a Jaguar supercharged V8 engine is used to power the oxidizer fuel pump for the Bloodhound's hybrid rocket.

Yes, it give some perspectives for turbo pumps then that small rocket need an 400 hp engine to drive the pump. 
 

[shynung]

2 hours ago, magnemoe said:

Yes, it give some perspectives for turbo pumps then that small rocket need an 400 hp engine to drive the pump. 
 

They could've gone this route, since their oxidizer is HTP (peroxide), which is a viable monopropellant. Why they didn't, I haven't an idea.

Edited June 13, 2017 by shynung

[magnemoe]

43 minutes ago, shynung said:

They could've gone this route, since their oxidizer is HTP (peroxide), which is a viable monopropellant. Why they didn't, I haven't an idea.

An car engine is cheaper and simpler, its also heavier but that is not very important, much simpler and safer than making an HTP turbine, they could also used the jet engine to run the pump, this also increase complexity. Had you used that hybrid engine in an rocket you would have used an HTP turbo pump and perhaps also used liquid fuel in the turbine for better performance. 

[p1t1o]

1 hour ago, magnemoe said:

An car engine is cheaper and simpler, its also heavier but that is not very important, much simpler and safer than making an HTP turbine, they could also used the jet engine to run the pump, this also increase complexity. Had you used that hybrid engine in an rocket you would have used an HTP turbo pump and perhaps also used liquid fuel in the turbine for better performance. 

Could it perhaps be related to something something throttling? Allows a deeper range of thrust variation compared to a turbopump based cycle?

[shynung]

16 minutes ago, p1t1o said:

Could it perhaps be related to something something throttling? Allows a deeper range of thrust variation compared to a turbopump based cycle?

It's possible to control the thrust by a throttle valve just before the pump, if using a turbopump.

[p1t1o]

10 minutes ago, shynung said:

It's possible to control the thrust by a throttle valve just before the pump, if using a turbopump.

I know, but generally you cant throttle them up and down willy-nilly from 0% to 100%. There will be pressure ratios and instabilities which mean that only certain area of the thrust envelope are operable.

[shynung]

Just now, p1t1o said:

I know, but generally you cant throttle them up and down willy-nilly from 0% to 100%. There will be pressure ratios and instabilities which mean that only certain area of the thrust envelope are operable.

True, though that comes with the advantage of a vastly simpler pump that doesn't require another type of fuel (gasoline) to be brought onboard.

[p1t1o]

18 minutes ago, shynung said:

True, though that comes with the advantage of a vastly simpler pump that doesn't require another type of fuel (gasoline) to be brought onboard.

Sure, sure. I'd counter with reliability, a turbopump would likely need to be a bespoke design, and runs under far more strenuous conditions, whereas the V8 is off-the-shelf, known to work. And if a turbopump fails it can cause catastrophic damage, if the V8 fails, the whole system will just grind to a halt, and the weight penalty is far, far less significant for a car than a space vehicle.

I mean, Im surprised there is a car engine in there too.

But didnt I read a thing about NASA looking into some kind of internal combustion, reciprocating pump for one of their engines...its a really vague memory...

Quick scan of the wiki page says that the V8 is also used as an auxiliary power unit. Providing significant power whilst the rocket engine is not running is definitely something a turbopump cannot do. I wonder if it is necessary for the operation of the jet engine.

[magnemoe]

12 minutes ago, p1t1o said:

Sure, sure. I'd counter with reliability, a turbopump would likely need to be a bespoke design, and runs under far more strenuous conditions, whereas the V8 is off-the-shelf, known to work. And if a turbopump fails it can cause catastrophic damage, if the V8 fails, the whole system will just grind to a halt, and the weight penalty is far, far less significant for a car than a space vehicle.

I mean, Im surprised there is a car engine in there too.

But didnt I read a thing about NASA looking into some kind of internal combustion, reciprocating pump for one of their engines...its a really vague memory...

Quick scan of the wiki page says that the V8 is also used as an auxiliary power unit. Providing significant power whilst the rocket engine is not running is definitely something a turbopump cannot do. I wonder if it is necessary for the operation of the jet engine.

ULA centaur replacement plans to use an internal combustion engine running on hydrogen boil of and oxygen for power and for pressurizing hydrogen and oxygen so it can be used instead of helium for tank pressure. It will also use pressurized H2 and H2 instead of monoprop for rcs, combined with cold gas h2.
Benefit is that you just need two gasses and that the hydrogen is free as it would boil of anyway. 
the heat from the engine is also use to heat the gas, increasing pressure. 

[shynung]

22 minutes ago, p1t1o said:

Quick scan of the wiki page says that the V8 is also used as an auxiliary power unit. Providing significant power whilst the rocket engine is not running is definitely something a turbopump cannot do. I wonder if it is necessary for the operation of the jet engine.

Jet engine usually come with some sort of alternator, so probably not necessary. However, jet engines are more fuel-hungry than piston engines, and taking electrical power from the jet would reduce thrust it produces. Makes sense to use the alternators on the V8 instead.

28 minutes ago, p1t1o said:

Sure, sure. I'd counter with reliability, a turbopump would likely need to be a bespoke design, and runs under far more strenuous conditions, whereas the V8 is off-the-shelf, known to work. And if a turbopump fails it can cause catastrophic damage, if the V8 fails, the whole system will just grind to a halt, and the weight penalty is far, far less significant for a car than a space vehicle.

A monopropellant turbo-generator can also provide auxiliary power without needing the rocket engine being on. Though, again this would be a bespoke design. The V8 is the easier solution to implement.

Though, I have a feeling that a Mazda rotary engine would have been more appropriate, due to their high power-to-weight ratio. I guess they chose a Jag engine because the team is based in the UK, and procuring Jag engines may be easier.

[p1t1o]

3 minutes ago, shynung said:

Jet engine usually come with some sort of alternator, so probably not necessary. However, jet engines are more fuel-hungry than piston engines, and taking electrical power from the jet would reduce thrust it produces. Makes sense to use the alternators on the V8 instead.

A monopropellant turbo-generator can also provide auxiliary power without needing the rocket engine being on. Though, again this would be a bespoke design. The V8 is the easier solution to implement.

Though, I have a feeling that a Mazda rotary engine would have been more appropriate, due to their high power-to-weight ratio. I guess they chose a Jag engine because the team is based in the UK, and procuring Jag engines may be easier.

Honestly, Im more interested in why the jet engine is there.

According to the blurb, the jet is there to get the car up to 300mph and the rocket pushes it to 1000mph.

The jet is huge, heavy and complex - what prevented them from just using a pure rocket design I wonder?

[shynung]

Just now, p1t1o said:

The jet is huge, heavy and complex - what prevented them from just using a pure rocket design I wonder?

I'm guessing that the rocket's dV budget isn't enough to push the car to 1000 mph, that the rocket runs out of propellant before the speed is reached. The jet engine may be there to ease the dV burden on the rocket, reducing propellant mass requirement.

[p1t1o]

3 minutes ago, shynung said:

I'm guessing that the rocket's dV budget isn't enough to push the car to 1000 mph, that the rocket runs out of propellant before the speed is reached. The jet engine may be there to ease the dV burden on the rocket, reducing propellant mass requirement.

To which I'd say that one-jet-engines-weight of rocket fuel is a lot of rocket fuel. But you are right, there may be restrictions from the design of the rocket, being a liquid-solid hybrid.

[shynung]

37 minutes ago, p1t1o said:

there may be restrictions from the design of the rocket, being a liquid-solid hybrid

Which is telling. Hybrid rockets aren't really known for high specific impulse. It's barely better than a typical solid rocket booster.

[Shania_L]

But you can turn off a hybrid if you need to, something you cant do with a pure solid rocket. When control and stability are issues and you have a man aboard being able to kill the thrust is an important safty consideration that may be worth the Isp penalty.

[Racescort666]

3 hours ago, magnemoe said:

ULA centaur replacement plans to use an internal combustion engine running on hydrogen boil of and oxygen for power and for pressurizing hydrogen and oxygen so it can be used instead of helium for tank pressure. It will also use pressurized H2 and H2 instead of monoprop for rcs, combined with cold gas h2.
Benefit is that you just need two gasses and that the hydrogen is free as it would boil of anyway. 
the heat from the engine is also use to heat the gas, increasing pressure. 

I figured I'd share this because I was just looking at it the other day.

Also, Jag V8? Sounds perfect for an LS swap.

[CSE]

6 hours ago, p1t1o said:

Honestly, Im more interested in why the jet engine is there.

According to the blurb, the jet is there to get the car up to 300mph and the rocket pushes it to 1000mph.

The jet is huge, heavy and complex - what prevented them from just using a pure rocket design I wonder?

I think the dry weight helps with stability at the end of the run - you're right about the modern challenge being control rather than speed. I seem to remember a source on the design choices for Thrust SSC, some years ago now obviously, giving this as the reasoning for the twin jets rather than a rocket.

[CSE]

http://www.thrustssc.com/thrustssc/Engineering/simpleds.html

Quote

Another unwelcome by-product of the rocket's fuel thirst is the dramatic change in weight from full to empty in a few seconds, a weight change likely to make a rocket-car more unstable rather than more stable the faster it gets. All of which leads to the inevitable conclusion that jets are an altogether more feasible proposition.

 

[shynung]

Cockpit of the Bloodhound vehicle. Apparently, much of the driver's view would be the instrument panel; that LCD above the steering wheel is pretty high to look over.

[Racescort666]

It doesn't look like the dashboard is much worse of an obstruction than other race cars. Although, it's hard to tell depending on the angle of the picture. The other thing that looks interesting, is the pedals. Are those rudder pedals?

[Steel]

25 minutes ago, Racescort666 said:

...The other thing that looks interesting, is the pedals. Are those rudder pedals?

Nope, they are in fact a brake and an accelerator pedal [1]

[Racescort666]

4 minutes ago, Steel said:

Nope, they are in fact a brake and an accelerator pedal [1]

That's pretty cool.