Hello Aspirant,

There are not many institute which provide diploma in aerospace engineering,

I am listing below a link in which you can check for the three colleges mentioned below and read about those colleges and even download there brochures to acknowledge yourself better.

1. Central Tool Room and Training Centre, Bhubaneswar

2. 
   Gurukul Vidyapeeth Institute of Engineering and Technology, Patiala

3. Apex University, Jaipur

Use this link to compare and know more about the colleges.

https://engineering.careers360.com/colleges/list-of-diploma-in-aerospace-engineering-colleges-in-india

I hope it helps.