lecture15 - ECE2984 Lecture15:LAUNCHANDREENTRY...

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ECE 2984 Lecture 15: LAUNCH AND RE ENTRY Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry
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Last Lecture LAST LECTURE: Course Project Exotic Propulsion: Electrodynamic thrusters Solar Sails Launch Window and Azimuth unch rofile nd elta Launch Profile and Delta V THIS LECTURE: More on Launch Staging Re Entry Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry After theShuttle
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Launch Review In order to reach a sustainable orbit at a particular altitude we eed nd ut xactly ow uch elta quired need to find out exactly how much Delta V is required: (1) Launch site velocity: rocket velocity prior to launch (2) Burnout velocity: rocket velocity at the desired orbit (3) Gravity loss velocity: altitude change velocity ty loss gravi e launch sit burnout needed V V V V + = Δ velocity change altitude change here g μ Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry Where + = = ε R V V orbit burnout 2
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Launch Staging Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry
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Apollo 11 Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry
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Staging h bit hi l d t i “E itVl i t” f 9 / To reach orbit a vehicle needs to acquire an “Exit Velocity” of 9 km/s. This requires a large quantity of propellant to produce the necessary thrust. More than 80% of the mass in a typical launch vehicle is propellant. The larger the mass of propellant, the less mass is available for a payload. One way around this problem is to use “Staging”. ch rocket “stage” consists of propellant tanks rocket engines and other Each rocket stage consists of propellant tanks, rocket engines, and other supporting subsystems. When the propellant in a particular stage is all used up the stage is discarded lighten the launch vehicle on the way to orbit. to lighten the launch vehicle on the way to orbit. The engines of the next stage ignite to continue the vehicle’s flight into space. Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry
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Multi Stage Launches 600,000 00,000 500,000 ht (lbs ) 00 000 300,000 400,000 h weig h 100,000 200,000 launc 0 one stage two-stage three-stage Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry Using multiple stages reduces the launch weight allowing for a larger payload
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Single Stage Launch Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry EXAMPLE: A single stage launch with engine I sp =480 s can put 84 kg into orbit
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Two Stage Launch Joseph Baker (ECE Dept) ECE 2984: Exploration of Space Lecture 15: Launch and Re Entry EXAMPLE: A two stage launch with engine I sp =480 s can put 175 kg into orbit
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aging Staging ADVANTAGES: Increased payload mass and/or increased V (i.e. higher orbit) Allows for use of a less efficient rocket (i.e. lower I sp )
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This note was uploaded on 09/19/2011 for the course ENGE 1114 taught by Professor Twknott during the Fall '06 term at Virginia Tech.

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lecture15 - ECE2984 Lecture15:LAUNCHANDREENTRY...

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