Aeronautical Engineering

No, you cannot get admission in Aeronautical Engineering course after completion of your Diploma course in Computer science, simple reason being that computer science has nothing to do with Aeronautical Engineering. Only candidates who have completed three years Diploma course in Aeronautical Engineering are eligible or qualified to get admission in Aeronautical Engineering course. To get admission in B.E/B.Tech course, you need to appear in Lateral entry examinations like LEET, ECET, JELET, etc., that is conducted by your respective state entrance examinations board. You have to clear the exam, and then based upon your examination rank, you will be allotted a seat in a particular college, where you get admission in second year of B.E/B.Tech course. It's not late, pursue the courses required and follow the eligibility rules, and you will surely achieve your dreams.
Secondly, this is the exact thing that will help you achieve your dreams, with Job outlook and salary scope:
Degree Level Bachelor's degree
Degree Field(s) Aeronautical or aerospace engineering or related major from a ABET accredited program
Engineering license may be required
Experience: None
Key Skills: Math and science aptitude; attention to detail and problem solving skills
Job Outlook (2014-2024) 2% decline
Median Annual Salary (2015) $107,830 (for aerospace engineer. Wish you luck for your future endeavors.

Hello Danish,
Yes, you are Eligible.
B.Tech Aerospace Engineering Eligibility:
1. A 10+2 examination (Pre-University Board Examination) with physics, chemistry, and Mathematics that are recognised by any State Board / Central Board (with a minimum aggregate of 50% marks).
2. The student should have the fundamental knowledge of computers and programming. Candidate should have passed HSC (standard. XII) State Board of Secondary and Higher Secondary Education or its equivalent examination with subjects English, Physics, Mathematics are compulsory and optional subjects are Chemistry / Biology / Biotechnology & Technical Vocational. Choose any one from the optional subject and secured a minimum of 50% marks (45% in case of Backward Class candidates)
3. Diploma (any specialisation) awarded by MSBTE or equivalent by any other Government body with a minimum aggregate of 50%.