IIT Madras - Indian Institute of Technology

Hello Jayaprakash,
This course has only 23 seats and usual government reservations apply. The entrance exam conducted is only for this course. Hence you need to be in 90 percentile at least to get admission.

Your marks should be 200 and above.

Hii Latha,
Hope you are doing good. Firstly, congratulations for getting qualified in JEE Mains. It depends on the branch you wish. On average in the worst case I think 35-40% in a tough paper is preferable. Please tell me the branch you wish in IIT Madras so that I could answer you accordingly.

The minimum JEE Main cut off 2018 (expected) for different categories is as follows:
-Common Merit List (CML) - 118
-Other Backward Class (OBC NCL) - 79
-Scheduled Caste (SC) - 56
-Scheduled Tribe (ST) - 50
Some of the colleges that offer aeronautical engineering include:
1.Bengal Engineering and Science University, Howrah
2.Indian Institute of Technology, Bombay
3.Hindustan Institute of Technology & Science, Chennai
4.Guru Gram Institute of Aeronautical Engineering and Technology
5.School of Aeronautics, New Delhi
6.Nehru Institute of Engineering and Technology.
Hope this helped :)

It seems impossible as you have to give JEE Mains for entering into IITs after 10+2 as IITs don't entertain lateral entry admissions.

You should have a project or a research project to go for internship there. You can connect with their research head and if they will be interested in your work then they can call you for internship.