# Tag Info

8

Does an ion thrust engine consume more energy as it speeds up? The answer to this question is no. So when it hits the top speed what is the bottle neck? The bottleneck is that the vehicle runs out of propellant. The problem is described by the rocket equation, $$\frac {\Delta v}{v_e} = \ln\frac{m_{\text{initial}}}{m_{\text{final}}}$$ Where ...

1

The limit in either case is when you run out of fuel. By the Tsiolkovsky rocket equation, if all else is the same, the top speed of a rocket is proportional to the exhaust velocity. So, the faster a rocket ejects its (often burning) exhaust, the higher the final speed when the rocket runs out of fuel. As a metaphor, imagine being in a boat filled with ...

5

That page is not well written. The 90km/s speed is the exhaust velocity of the engine. It is not the maximum speed of the spacecraft. There is no maximum speed of the spacecraft, short of the speed of light. They make the mistake again when they say: "While a chemical rocket's top speed is limited by the thermal capability of the rocket nozzle" ADDED: ...

1

The hot molucules of the burning fuel move rapidly to all directions with equal probability inside the burning cavity. This means that if the cavity were closed, for any molecule that impacts on one point in the interior of the cavity there would be (statisticaly) another one impacting anti-diametricaly and with the same rate; this would not cause any thrust ...

15

You have the general idea right, but the following statement is subtly wrong The pressurized fuel/air mixture is ignited and this increases the pressure inside the combustion chamber even more Unlike in a piston engine, the ignition of the fuel air mixture in a turbine engine increases the mixture's volume while pressure stays relatively constant. ...

9

With respect, if you want to fully describe the operation of the modern jet turbine engine, you should consider the greatest change in the last 30 years or so, which has been the development of the large multi-bladed fan at the front of the engine. Most modern jet turbine engines are of the high bypass design, with a large fan placed in front of a central ...

7

Yes - although whether it provides "useable power to a shaft" depends on the kind of jet engine (it is possible but not necessary). For example, a turbojet does not provide "useable" power to a shaft - it just drives the compressor. A turbofan engine has a bypass path: the compressor does not send all the air to the combustion chamber, but some of it ...

2

Yes, your outline is correct. The power extracted by the turbines is used to power the compressor system to keep the system going. 'suck-squeeze-bang-blow' as engineers like to say. Rolls-royce the jet engine book is a good high level overview.

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