@ kiran rc,
Outstanding work, as expected from you!
If 4gms AUW is correct, its a real achievement. My 9” HLGs are in 9-10gm range!
You said you used 0.75mm balsa. I can see that the stab, fin and pylon look like 1/32”, or 0.75mm.
But the wing?
From the airfoil shape and a close look at the thickness of the left tip in the first pic, the wing seems to have been
carved from 2 or 3mm balsa, and not
curved from 0.75mm sheet.
Which one is it?
Your balsa stock seems to be of contest quality (6lbs/cuft or less). Where did you get it?
Can you weigh one of your sheets and tell me?
(6lb/cft weighs about 10gms per 1mm thickness in a 100mm x 1000mm sheet)
BTW, the wood grain for the pylon needs to be vertical, not horizontal. Reason will become apparent when you try a full power throw
Await test flight video...