One strategy for Angry Birds Bad Piggies level 21-8 is to use the Red bird to topple the stones atop the tower, clearing the pigs on the right side of the level. Tip the left tower by sending a Yellow bird into the bottom-left corner. The falling debris should detonate the TNT within. The score in the video below is 107,560.
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.

First bird on second pig counted from left. Bird rolled downward to the left killing the first pig counted from the left. Then second bird same trajectory accelerating late. TNT blew up and everything collapsed well to the right plus taking out the 3 wrenches and over it was.
@emider, thank you! Again!
Thanks for the tip @emider. Best strategy so far.
@emider, As many have told you already, this is a great strat! Nice work! how long my score stays above the average is iffy. When I updated this score in the LB, I was under the average in 4 of the 8 levels of this section. I was only under in one 30 minutes ago.
Thank you! Great strategy! If you manage to get the debris to hit the golden wrenches you can get an even higher score.
Worked nicely, thank you @emider. Improved my score due to your strategy. But got 2 wrenches.
Ok I’m confused @emider by second pig counted from the left, you mean the pig on the lower shelf?
Looks like you figured it out @Kathy? :) Thank you emider, I was doing it the way the video was showing at first but once I popped in here and saw your strat I gave it a few tries! Yeay!! :)
@emider,
Good strat. However, the first bird doesn’t actually matter. The only thing that counts is that the yellow bird detonates the tnt. From then on it’s a matter of luck, to what directions the debris is falling and how much. But, with your strat I detected the wooden entry for yellow bird.
Thanks @emider for the strat! However, this level was so annoying to me. The YB often likes to get stuck and doesn’t like to roll back to hit tnt most of the time. Here’s a few tip for those of you that are frustrated as well:
I found if I sent the first bird a bit on the high side through the pig, it kinda knocks the top part to the right a little, helping to set up for the second shot.
Second bird, I found that you can ignite the tnt more often if you aim YB very low, even through the horizontal plank and accelerate last minute! This seemed to allow for YB to roll back more often or allow for the cement plank below the wood to hit tnt. Then it’s a matter of getting as much to fall to the right and hope for the keys ;-)
Thanks! I managed to cross the 100k with your strat.
Has anyone been able to achieve a one bird solution for this level? The first shot described by @emider leaves the already wobbly structure even more unstable. I’ve waited a minute or so to see if it would topple, but lost patience. It seems possible, though.
Yes. My 117,580 is a one birder. Hit the upper stone triangle just right. Structure very slowly collapsed. Basically, the goggles/flight hat was stuck under some debris causing the structure to wobble. In about 15 seconds, the long stone planks fell onto the TNT….and one birder. Score isn’t any better than two birders discussed above, but probably could be much better with more debris damage possible. @zipbird
I just got a 1-Birder using the suggested strat by @emider, the first Bird destabilized the entire structure causing it to fall apart, but the TNT didn’t explode…Hence my low score.
127470 with 2 birds as per strategy mentioned above ! No much to explain here, the only thing is that somehow the tnt exploded at the very end of the collapse. This is maybe the trick explaining such a high score… Hope this helps and good luck to all
http://imageshack.us/photo/my-images/836/img1609.png/