One strategy for Angry Birds Free Bad Piggies level 21-3 is to arc a Yellow bird through the rotors of the helicopter flying above the main level. Then send another Yellow bird straight ahead into the structure, aiming to blast the TNT on the far right side.
This is Level 21-7 from Bad Piggies in the full Angry Birds app. Feel free to check out that page for more strategies.
If you have a different method that is easier or yields a higher score please feel free to leave a comment below explaining your strategy. Please don’t post your score in the comment section without an accompanying explanation on how that score was achieved. For those looking to post individual scores, head on over to the leaderboards and compete with the rest of us!
1. Let the helicopter fly to the right and just as it is coming back to the left take the shot with the Yellow Bird. Zoom out for the shot.
2. High arc the Yellow Bird so it comes down through the right tip of the helicopter’s blade. Activate the YB on its downward travel path so it destroys the purple jewel in the base rock. The tnt also gets activated and if one gets lucky, the gold wrench gets destroyed.