One strategy for Angry Birds Bad Piggies level 21-7 is to use one Yellow bird to cut the propellers of the helicopter. Fire another Yellow bird straight ahead, detonating the TNT within via impact and blowing the structure sky-high. The score in the video below is 105,430.
If you have a different strategy feel free to leave a comment below; however, don't just post your score via the comments, as that's what the leaderboards are for.

I was doing it a bit differently from the video and the score was always no higher than 96k, so I did it exactly as on the video and after 3 tries got the present score with the 2-Birder, but, I believe the 1-Birder is just around the bend.
I got the one-birder just now. The video has mostly the right idea, but is too impatient. Wait a few seconds longer, so that the helicopter is just starting to move to the left again, and then fire the bird in a high arc. The goal is to sever the right side of the blades and continue straight through the thinner wooden supports into the channel with the purple gem. This normally leaves the TNT and the furthest pig intact, but I got lucky once and it all collapsed with the first bird for 115k.
@austinrhl, thank you! Didn’t get a 1-birder (yet!), but did get a nice 2-birder for 111k. Can’t tell you how much comments like yours are appreciated :)
After a dozen more tries, I managed a 1-birder for 113k, TNT on right did not explode.
@bonneypattycat, you’re very welcome! It’s always gratifying when you’re able to help other members relieve their frustration and/or improve their scores.
That is a nice one bird strategy Austin.. Very repeatable after some practice I one birded the level at least a dozen times but my best score still came with 2 birds.
“Get to the choppa!” Interesting approach and a fun shot to work out the timing and alignment. After that, it’s just a matter of repetition until you get everything right in the same turn. I did get a 1-bird finish but the score wasn’t what I wanted. A 2-bird solution worked better: I wanted to get the gem and blow the TNT. @austinrhl
@ohforfive love the quote, gave me a laugh. Nothing like a little Arnold to start my day :)
I never got the 1-birder to work, but it gave me great destruction of the front part, got 115k with 2 birds.
I was hoping anyone would pickup on the Arnold reference. Glad to see you’re a fan.
@karen68, I forgot to add your tag to my comment.
Thank you again :D. This got me top score for the moment
http://angrybir.de/Ubrznv
@AustinRHL, thanks for the tip. Hopefully can improve a bit more.
Ty @AustinRHL darn i got a o one Birdie but not a good score..above average that’s it:(
Guess I’ll keep flingin’ keep flingin’ keep flingin’
Thanks @austinrhl for the post on the one-bird alternate strategy. It was fun because of all the different outcomes and scores that result. Getting Yellow Bird to go through the little wood planking into the jewel was just a matter of aim and timing. Found that the release point close to the blade appeared to work more consistently. The waiting of 6 seconds as mentioned by someone else was also a good tip. I had the two spanners remaining for this score.
Nice job @austinrhl and others who got the one birdie with the crystal AND the tnt!!! I have managed several one birdies but I got 112100 when I missed the crystal and 114750 when I got the crystal but missed the tnt! Urgh!!! I will have to try again another day as it is very difficult for me to rinse and repeat with the 6 second delay needed, lol…I realize how pathetic that sounds but 6 seconds is 6 seconds and it’s frustrating to have to wait upon each reset, lol ;-)))
Thank you @austinrhl for your one-birder strategy! It is easily repeatable and although I couldn’t get the golden wrench, I’m happy with my 118520 score.
Looks like @moondoggie got the wrench! Congrats moondoggie :)
Thanks, @bonneypattycat . Like @austinrhl, I waited ~6 seconds before firing YB in a high arc clipping the very tip of the right helicopter blade. Nothing but wood and crystal, then the TNT went and had a very good collapse. Unfortunately I didn’t check to see if the wrench was gone, but I assume it must have.
@Kimmiecv did you make here yet? The strat above by AustinRHL is the way to go:)
Wait a few second till the chopper comes back to the left, you want to just clip the right edge barely of the propeller do as yb can speed into the shaft with the purple jewel. Oh and i didn’t accelarate till just before hitting..i know i don’t have the best score, but I’m still working on it:) good luck..
Ok I just got here @Kathy! I will read his strat and give it a try!! I Hate moving targets!! :/ but I think I got over avg now I just gotta see if I can up my score more!! :)
This is how I shot my first bird. I have not been able to get more than 108k with the one birder. 114,660 with two birds so far. Must figure out the keys to the one birder.