Getting good timings from tumblers

[hari]

Hi everyone,

i am hari from india. I keep a few tumblers. The breed i keep usually fly an average of 5 hrs. But my birds drop after flying for like 30 mins. My birds are in their 5th primay i feed them once a day in evening and fly them in morning. Any tips and advice are welcomed.

Thanks and regards,
hari