Bloodhound SSC

adolf hamster said:
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sometimes wonder why no nutter hasn't just tipped a space shuttle booster on its side and bolted some wheels to it, half a million horsepower anyone?
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Nobody with enough money is that much of a nutter and suicidal, because that would be suicide. The most difficult part isn't generating enough power. It's making a vehicle that can be driven (piloted?) from 0-1000-0 without destroying itself. The requirements at lower speeds are very different to the requirements at higher speeds. Too much or too little downforce at any speed and the vehicle is destroyed. Deviate slightly from a straight line and the vehicle is destroyed. If almost any part fails, the vehicle is destroyed.

Handling apparently gets rather sketchy above about 500mph, since the vehicle is essentially terraplaning and has no grip at all. Steering is minimal (and you're steering with the back wheels, which complicates matters anyway) and the slightest variation will move the vehicle. The slightest wind, the slightest imbalance in weight distribution, the slightest change in terrain and you're drifting sideways. Do that more than slightly and you'll rash and die. On Thrust SSC's runs, Andy Green had the steering on full lock at >600mph in order to keep it in a straight line because that was just the right amount of steering.

It's not primarily about the power.
 
Good series of interviews from Peter Windsor with Andy Green, there never seemed to be a number 1/5 and 2/5 seems very much like the first one.


So tempting to sign up to the gold club £75 just to get to go see, one if the runway tests in the uk. In fact my dad would love that, hmm maybe a treat for me, and Christmas present for my dad.

http://www.bloodhoundssc.com/shop/1k-club-membership

And who wants to buy me a 3d printer and model rocket jet engine, imagine making a scale rc car, that would be awesome.
 
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These guys have beaten them to it.

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I've just been idly doing some rough sums for the scenario of launching Bloodhound into space by standing it upright and letting rip. The question popped into my mind so I thought about it. How long would the Bloodhound engines have to run for in order to escape the Earth?

I get a ballpark figure of about 9 and a half minutes. If there's anyone here who knows more, I'd like to know how (in)accurate my figure is.

I'll show my working out for teacher :)

Force up (from the engines) is about 206 KN. Force down (from mavity) is about 69 KN. So net force upwards is about 137 KN. Mass is about 7000 Kg. So acceleration is about 19.5 m/s^2. Escape velocity is about 11200 m/s^2. 11200/19.5 = 574 seconds.

I know that they can't run for that long and if they could it would take a lot more fuel which would mean a lot more weight, but it was just an idle thought so I ignored that and went with a weight of 7 tonnes (6 for the car, 1 for the fuel). And I'm ignoring air resistance. And the fact that it's not designed to travel at 25,000 mph in air. And this is starting to sound like the "What have the Romans ever done for us?" scene :)
 
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MooMoo444 said:
What sort of MPG will it get?
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Hmm...I have an urge to concoct an estimate.

The rocket burns 1000 Kg of fuel in 20s, so 50Kg per second. Density of hydrogen peroxide is 1.45g/cm^3, so 50Kg of it is about 34.5 litres.

The jet's fuel consumption is given as 47-49 g/KN-s. So, er...about 90KN of thrust from it, so that's about 4.5KG per second, I think. Density of jet fuel is about 0.81g/cm^3, so 4.5KG of it is about 5.5 litres.

So that's about 40 litres of fuel per second.

At 1000mph, a mile takes 3.6 seconds. So that's 144 litres of fuel per mile. About 31.7 gallons per mile.

The F1 engine adds a bit more, but I'd be making a vague guess at best for the fuel consumption. I'd say maybe about 3 MPG, so maybe about 32 gallons of fuel per mile overall.
 
Angilion said:
Hmm...I have an urge to concoct an estimate.

The rocket burns 1000 Kg of fuel in 20s, so 50Kg per second. Density of hydrogen peroxide is 1.45g/cm^3, so 50Kg of it is about 34.5 litres.

The jet's fuel consumption is given as 47-49 g/KN-s. So, er...about 90KN of thrust from it, so that's about 4.5KG per second, I think. Density of jet fuel is about 0.81g/cm^3, so 4.5KG of it is about 5.5 litres.

So that's about 40 litres of fuel per second.

At 1000mph, a mile takes 3.6 seconds. So that's 144 litres of fuel per mile. About 31.7 gallons per mile.

The F1 engine adds a bit more, but I'd be making a vague guess at best for the fuel consumption. I'd say maybe about 3 MPG, so maybe about 32 gallons of fuel per mile overall.
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So slightly more economical than a HUMMER?
 
Angilion said:
Force up (from the engines) is about 206 KN. Force down (from mavity) is about 69 KN. So net force upwards is about 137 KN. Mass is about 7000 Kg. So acceleration is about 19.5 m/s^2. Escape velocity is about 11200 m/s^2. 11200/19.5 = 574 seconds.

I know that they can't run for that long and if they could it would take a lot more fuel which would mean a lot more weight, but it was just an idle thought so I ignored that and went with a weight of 7 tonnes (6 for the car, 1 for the fuel). And I'm ignoring air resistance. And the fact that it's not designed to travel at 25,000 mph in air. And this is starting to sound like the "What have the Romans ever done for us?" scene :)
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You wouldn't have to get to the escape velocity though, that's the speed you'd need to launch something from the surface to escape with no further propulsion. Acceleration would change as the higher you go the weaker the effect of mavity, as well as thinner air though you've ignored that.
 
Phantom Shadow said:
You wouldn't have to get to the escape velocity though, that's the speed you'd need to launch something from the surface to escape with no further propulsion. Acceleration would change as the higher you go the weaker the effect of mavity, as well as thinner air though you've ignored that.
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This... plus the acceleration would increase as the mass decreased as fuel and peroxide is used up.
 
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