火箭设计-火箭发射控制器

A presentation on Introduction Since the introduction of low-cost model rocket engines in the 1950's, building and launching small scale model rockets have been popular pastimes. While designing and finishing high-performance models is both interesting and challenging, it is also fun to design and build electronic gadgets to go along with them. One such gadgets is the Time Delayed Launch Control in this article. With the Time Delayed Launch Control, you press the fire switch to initiate a launch sequence, then the circuit begins to count-down, giving you plenty of time to step back so that you can view the impending event from a safe distance, record the launch, or prepare to monitor experiments during the flight. At the end of a preset period, the circuit ignites the rocket's engine, sending it skyward. The circuit has six preset delay intervals: 5, 10, and 30 seconds, and 1, 5, and 10 minutes. The circuit also contains a piezo-electric buzzer that beeps every few seconds as the system counts down to launch. As a safety feature, a launch sequence can be aborted at any time, simply by shutting off the system or by switching to the test-mode. The main function of the test mode, however, is to verify, via a front panel indicator, that the ignition circuit is properly wired. The circuit is powered from its own internal battery pack, which also provides power to the rocket- engine igniter. Circuit Diagram The circuit-which gives a choice of 6 delay settings--is comprised of three 555 timer/oscillators (U1, U2, U3), a pair of transistors (Q1 and Q2), four switches (S1 - S4), a piezoelectric buzzer (BZ1), and a few support components. Circuit description Power for both the control circuit and the rocket-engine igniter is provided by a 6-volt power source that is comprised of 4 AA-cell alkaline batteries. Alkaline batteries are specified because other types are incapable of supplying the 1-3 amps required to fire a rocket-engine igniter. Closing switch S1 feeds power to the launch control circuit, but does not initiate a launch sequence. A pair of series RC circuits (R4/C9 and R8/C12, respectively) are used to de bounce the reset inputs (pins 4) of U1 and U2 (a pair of 555 oscillator/timer IC's), thereby, preventing false triggering from occurring during power-up or when switching modes. Pull-up resistors R1 and R2 effectively shunt capacitor C1, keeping it discharged until S2 (Fire) is momentarily closed. When S2 is closed, C1's negative terminal is connected to ground through the switch, momentarily pulling pin 2 of U1 (which is configured as a monostable multivibrator, or one-shot) low, activating it. Once triggered, U1's output goes high for an interval that's determined by R3 and one os six timing capacitors (C2 through C8). The timing capacitor is selected via Delay Selector switch S3. Positions 1 through 6 of S3 give intervals of 5, 10, or 30 seconds or 1, 5, or 30 minutes, respectively. The high output of U1 at pin 3 is fed through current-limiting resistor R12 to the base of Q2, forward biasing it, which causes Q2 to turn on, allowing the piezoelectric buzzer (BZ1) to turn on when the proper signal is applied to BZ1's negative terminal. Monostable U1's output is also fed to the reset input of U3 at pin 4, causing it to oscillate with a duty cycle of about 75% (as determined by C14, R10, and R11). As long as the output of U1 is high and the astable is oscillating, BZ1 beeps once every 4 seconds. Resistor R5 discharges coupling capacitor C10 whenever U1's output goes high, while R6 maintains the normally high bias voltage required at U2's trigger input (pin 2). At the end of the selected time delay, U1's output goes low. That low is coupled through C10 and D1 to the trigger input (pin 2) of U2, which (like U1) is configured as a monostable multivibrator. Components R7 and C11 set U2's high-output interval to approximately 3 seconds. During that 3-second interval, U2's high output at pin 3 is fed to Darlington transistor Q1 through R9 (which limits the bias current to the device to less than 40 mA). With S4 in the Launch position, Q1 grounds one end of the engine igniter, effectively connecting it to the battery's negative terminal. During that 3-second interval, approximately 1-3 amps passes through the engine igniter, causing it to glow and burn. Block diagram of Modified MRLC Circuit diagram of modified MRLC Controller unit model 1. Flexibility As we know that the controller circuit uses timer ICs which has no other meant rather than generating different time delays. The time delay provides the scheduled operation to the rocket launcher to ignite its engine. In short, the three timer ICs produces 6 delay times i.e.5,10, 30 sec & 1, 5, 30 min. We can use multiple pads also. 2. Compact The size of the whole section is limited so it can be mounted in a single black box. Because of compactness, it has the ease of transportability. 3. Ease of maintenance The circuit diagram of the controller consist of IC 555, IC 4017 & other electronic components like resistors, capacitors, transistors etc. therefore, the use of this circuit provides ease of maintenance. 4. Effective & efficient performance 5. Test mode is available The modified time delayed rocket launcher controller provides test mode. The main function of the test mode, however, is to verify, via a front panel indicator, that the ignition circuit is properly wired. Advantages From the above discussion we can compare both controller circuitry. The second one is more preferable than the first one, because you can select more than one pad via pad selector. The controller circuit is used in the rocket launcher to give a scheduled functioning of launching of rockets. These are applicable for the rockets having moderate size & small size. The launching becomes more powerful & effective. It provides a plenty of time, so that we can see and calculate the readings during launching. Conclusion