探空火箭酬載機盒設計

Abstract

探空火箭的開發研究，帶動了導航電腦等探空領域相關的研究，由於軍規或是太空規的產品難以取得，因此本研究設計一個能扺擋外在惡劣環境的客製化機盒，保護商規元件，達到軍規或是太空規元件的要求。 本研究酬載機盒的設計重點在於透過機盒的結構與機構設計以固定酬載（導航電腦系統），降低位移量和振動的應力；並透過散熱片設計，使機盒內温度能均勻快速發散，保護盒內設備正常運作，不受外在的温差所影響。另外，機盒在不影響結構強度的條件下進行輕量化/多固定孔設計，以適應酬載空間狹小的火箭。 在機盒設計過程，我們利用電腦輔助設計，建立組裝模型、振動及熱分析模型，模擬結果比對經驗公式、規格書及實測數據。以降低實作的時間及實驗花費。研究結果顯示：機盒本體在不影響結構強度的情形下，可輕量化至568.7g，與初步設計相較之下，減重40%。在温度方面，在4分鐘自然對流條件下，機盒可達到650°C內外温度差的屏蔽效果，可將初步設計中的操作溫度55°C提高至70°C。在振動防護方面，降低導航電腦PCB板30%變形量及12%的應力。此結果證實本機盒設計符合軍規 MIL-DTL-5015的標準。另外，導航電腦在此機盒保護下，已順利隨火箭升空，完成相關任務。

The recent development of the hybrid rocket has attract more and more attentions from industry. People believe that the era of the space economy is coming soon. To ensure the rocket can be functioning well under the space environment and the launch conditions, the fly computers in use must be either military grade or space grade. The parts with either military grade or space grade are expensive and difficult to acquire.Therefore, the research goal of this project is to design a box, which hosts the payload (or fly computer) with commercial grade, so that the "components in the box "can function well under the sever environment. This research focuses on the design of a box and the fixtures that host the fly computer. With the proper fixture design, the fly computer would experience less vibration and thus less stress and deformation under high-g movement. With proper heat dissipation design, the fly computer can work at higher environment temperature. With proper box geometry design, the fly computer can be fit in the tiny space inside the rocket without much weight increase from the box. The results show that the weight of the box is 568.7g, which is 60% of our first-cut design. In terms of temperature, under the natural convection for four minutes, the box can establish a 650 °C temperature difference between in-and- out of the box. Thus, the fly computer can work under the device surface temperature of 70°C with the chip temperature less than 55 °C. In terms of vibration protection, the design reduces 30% of PCB board deformation and 12% of stress. All these results confirm that that "the fly computer in the box " are complied with the military standard MIL-DTL-5015.