OT: What is acceleration? (it's got V8's in it.......honest!)

Definition of Acceleration

One Top Fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500. Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced. A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster's supercharger. With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition. Cylinders run on the verge of hydraulic lock at full throttle. At the stoichiometric (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture for nitro methane, the flame front temperature measures 7,050 deg F. Nitro methane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases. Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder. Spark plug electrodes are totally consumed during a pass. After halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 degrees F. The engine can only be shut down by cutting the fuel flow. If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half. In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate an average of over 4G's. In order to reach 200 mph (well before half-track), the launch acceleration approaches 8G's. Dragsters reach over 300 miles per hour before you have completed reading this sentence. Top Fuel engines turn approximately 540 revolutions from light to light! Including the burnout, the engine must only survive 900 revolutions under load. The redline is actually quite high at 9,500 rpm. Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimated $1,000.00 per second. The current Top Fuel dragster elapsed time record is 4.441 seconds for the quarter mile (10/05/03, Tony Schumacher). The top speed record is 333.00 mph. (533 km/h) as measured over the last 66' of the run (09/28/03 Doug Kalitta). Putting all of this into perspective: You are driving the average $140,000 Lingenfelter "twin-turbo" powered Corvette Z06. Over a mile up the road, a Top Fuel dragster is staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line and past the dragster at an honest 200 mph. The 'tree' goes green for both of you at that moment. The dragster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums and within 3 seconds, the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him. Think about it; from a standing start, the dragster had spotted you 200 mph and not only caught, but nearly blasted you off the road when he passed you, all within a mere 1,320 foot long race course. ......and that my friend, is ACCELERATION!

Reply to
Neil Brownlee
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Twas Tue, 20 Jul 2004 14:42:46 +0000 (UTC) when "Neil Brownlee" put finger to keyboard producing:

Not to put too fine a point on it.... s*1t!.

Regards. Mark.(AKA, Mr.Nice.)

Reply to
Mr.Nice.

in article cdjb16$g0n$ snipped-for-privacy@hercules.btinternet.com, Neil Brownlee at snipped-for-privacy@pccontrolNOSPAMsystems.com wrote on 20/7/04 15:42:

Yes but can it drive down a greenlane!

Reply to
Rory Manton

Tonight, there being nothing much on TV, I shall be playing my DVD of a film called "The Dish".

Amongst the extras is film of an application of real power which, 35 years ago, made a journey possible which, today, nobody on Earth would be able to repeat.

The Saturn V launcher and Apollo spacecraft massed about 6 million pounds, over 2700 tonnes, and in the first two minutes of flight the First Stage, with five F-1 engines burning Kerosene and liquid oxygen, burns over 2000 tonnes of fuel, a rate of over 3 tonnes per second per engine.

The noise generated is so intense that if the water were not to be sprayed into the flame trench, the reflected energy would destroy the Saturn V.

The hold-down clamps which anchor the whole column, 346 feet high, to the pad must hold the Saturn V down until the engines have started, against a net force of 1,5 million pounds, and then release simultaneously.

The initial acceleration is small, only a quarter of a gravity, but at first stage burnout, thirty miles up and two minutes later, with all that fuel burnt, the acceleration in a vertical climb would be 3.8 gravities. But by they, outside most of the atmosphere, the Saturn V is mostly accelerating horizontally, picking up the tangential speed needed to sustain orbit.

And thirty five years ago tonight, a vaguely spider-like craft, carrying two men, within seconds of running out of fuel, landed on the Moon. Over the radio came the first words spoken by a human on another world.

"Houston, this is Tranquility Base. The Eagle has landed."

And on the 28th October 1971, the only all-British satellite launch took place. Black Arrow number R3 carried the Prospero satellite into orbit. Perhaps appropriately, the combination of kerosene and hydrogen peroxide used meant that Black Arrow rose into the sky of Woomera on a column of superheated steam.

Reply to
David G. Bell

Nah !! My Year 9 class on the way to lunch, .......... now that ... is real acceleration

Reply to
Hirsty's

I'd like to see that proven. 747's have been fitted with RollsRoyce RB211 engines amongst others, which provide a spectacular thrust. Let's see some power/ton figures for both the dragster and the 747. I work daily testing RB199 engines, which in Combat setting provide approx.

70kN (7 tons) of thrust each, at a mass fuel flow of approx. 4800kg/hour, the fuel s.g. for those who wish to convert to gallons is 0.798. I've a sneaky feeling that the thermal efficiency of a jet engine is way better than an internal combustion one. Badger.
Reply to
Badger

Has to be. The temperature differential through the engine is much higher.

Steve

Reply to
Steve Taylor

Good one Badger, I think you may be right as the olympus engine was reckoned to be very efficient at turning heat into thrust, it lost a bit when they had two running into a third turbine to run a generator.

Now with a pressure ration of 44 in a modern aero jet we could probably work out the likely bounds of the conversion if we knew the peak pressure in the reciprocating engine.

AJH

Reply to
sylva

You hope.

P.

On his way to play with adjusting everything adjustable on his 200TDI

Reply to
Paul S. Brown

Still not as fast as Sammy Millers Rocket car dragster of the early

1980's!.

Dom J

Reply to
Dom J

Nitromethane has a density of 1.124 to 1.129 and a specific energy of

11.6 MJ/kg. Avtur comes in at 0.775 to 0.840 and a specific energy of at least 42.8 Mj/kg.

From this it's clear to see that a gallon of nitromethane only contains about a third of the energy that a gallon of avtur does. So in raw terms the original statement is completely wrong.

Now, I don't have thermal efficiency figures for either dragsters or jet engines, but seeing as how jet engines are designed with efficiency in mind and dragster engines aren't, I'm not expecting the dragster to be able to make up the ground it's already lost.

But I'm willing to be wrong on this one!

Reply to
QrizB

'cept you confuse force (Newtons) with energy (Joules)

It gets more complicated because the jet may be developing thrust (force) at the same rate throughout the take off (i.e. burning fuel at the same rate) but that does not result in a constant power because power is thrust times velocity, so the jet gets more useful conversion of heat to kinetic energy of the plane the faster it travels, I think ;-).

Reply to
sylva

On or around Sat, 24 Jul 2004 21:33:40 +0100, snipped-for-privacy@despammed.com enlightened us thusly:

also you get interesting results from varying the mass. the simple equations of motion which are commonly used treat mass as a constant, and say "F=ma" for example. in fact, F=d(mv)dt, rather than the F=m.dv/dt which is implied by the former. In the case of both the dragster and the boing, they may burn fuel fast enough that the mass change becomes significant. Certainly is with rockets going straight up - initial acceleration is low due to the heavy mass, then as the fuel is consumed the mass reduces so the acceleration increases.

in fact, on the jet, it's probably not really significant; I don't think it uses that much mass of fuel to take off, compared with the gross weight.

Reply to
Austin Shackles

IIRC a figure of 11tonnes to get a 747 to cruise speed and height, perhaps we should convert these to 0.5MV^2+MGH and see how much work that fuel did ;-).

AJH

Reply to
sylva

On or around Sun, 25 Jul 2004 10:55:31 +0100, snipped-for-privacy@despammed.com enlightened us thusly:

hmmm. how much does an all-up 747 weight to start with though?

Reply to
Austin Shackles

A google gives 377,800kg inc 196,515ltr fuel!

AJH

Reply to
sylva

On or around Sun, 25 Jul 2004 14:32:00 +0100, snipped-for-privacy@despammed.com enlightened us thusly:

hmmm. jet fuel is probably about .8 kg per litre... feckinell, that's about half the all-up weight. Mind you, it goes a fair distance on that much.

Reply to
Austin Shackles

I've read somewhere that the workshop manuals, spare parts books and "don't touch that bit' bulletins for a 747 add up to more than the weight of the aircraft. Imagine the shelves in WH Smiths that could hold a Haynes Manual the weight of a 110!

Steve Durban

1984 110 V8

snip

Reply to
Steve Maloney

On or around Mon, 26 Jul 2004 20:33:04 +0200, "Steve Maloney" enlightened us thusly:

The maunals for DEC computers used to be impressive, great row of orange (or grey, depending on model) folders.

inluded the immortal line about specifying the timeout for operator intervention in the evnt of a power failure and subsequent auot-reboot. The timeout, it says, is specified in microfortnights, which approximate to seconds.

Reply to
Austin Shackles

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