Flying Fortress

"This is a BIG plane."

- Official description

 is the final upgrade of Path 3 for the Monkey Ace in BTD6. It shoots 3 streams of darts and bombs, each of which fire +50% faster (from every 0.06s to 0.04s). The 3 streams of darts and bombs target the first, last, and closest bloons, respectively. Darts now deal 4 base damage instead of 2, and bombs now deal 5 base damage instead of 3, in addition to +2 Ceramic damage for both attacks. The Flying Fortress darts and bombs can pop any bloon type, including DDTs, although it needs camo detection (e.g. the Spy Plane upgrade) to detect Camo Bloons.

It costs $72,250 on Easy, $85,000 on Medium, $91,800 on Hard, and $102,000 on Impoppable.

Appearance
The Flying Fortress is one of the largest flying towers in the game. It is a light-black-colored monoplane with a long elevator plus its two tailwings at the end connected by two tail connectors. It has three red propeller holders and three respective white propellers on each wing, alongside a blue-and-red target symbol near the end of each wing (in-game tower and Instamonkey icon only). The plane also has two rows of five windows at the front.

The upgrade icon for the Flying Fortress depicts a Flying Fortress plane flying directly forwards shooting a barrage of highly damaging bombs and darts at the ground.

Tower Prices

 * Updated as of Version 30.0

Summary
At a very expensive price, Flying Fortress demolishes various types of bloon across any range in just a short amount of time, but its projectiles often miss fast bloons such as visible DDTs. Slowdown support such as Bloon Sabotage and/or MOAB Glue can help give the Flying Fortress an easier time handling DDTs. Extra support via Radar Scanner is highly recommended on top of Jungle Drums to improve its performance even further, especially with the 2-0-5 Flying Fortress crosspath.

Getting a buff from the Alchemist normally isn't a good idea, as the buff wears off faster based on how fast the tower is attacking, but for this exact reason, Permanent Brew is an excellent choice for a good lategame tower combo. This is due to the fact that the alchemist buffs popping power per projectile and the flying fortress shoots a lot of projectiles very fast, every single one being affected by the buff. In fact, a super-buffed Flying Fortress outputs a huge DPS bonus outside of Sun Temples, True Sun God, and Paragons.

While Flying Fortress is impractical on CHIMPS, it still has its uses on CHIMPS. However, in the saveup for it, it needs to be affordable by the start of Round 95, given that the aforementioned round is nearly impossible with only a small amount of cash while also surviving subsequent and earlier late-game rounds. Most basic defenses with a very high potential for CHIMPS budgeting help afford Flying Fortress on time, particularly in combination with Sauda and MOAB Glue.

Tips

 * Like the Spectre, place the Flying Fortress near the exits. It should be attacking the front line of the bloons if you don't have its path set to Centered Path.
 * It deals great damage against huge clusters of bloons, but it tends to fail against fast and/or spaced bloons, due to how slow each of the projectiles are. Therefore, it should not be used as the main popping power. Consider adding other towers to help counter this weakness of the Flying Fortress.
 * When upgrading the Flying Fortress along the other paths, it is best to upgrade to Path 1 (Rapid Fire and Lots More Darts) rather than Path 2 (Exploding Pineapple and Spy Plane), since by then Camo detection is easily accessible and an increase in its already massive attack speed and pierce is much more helpful. Also, the pierce and blast radius bonus from Exploding Pineapple crosspath for bombs doesn't do much because Flying Fortress already attacks so fast and deals such huge damage.
 * On most single-path tracks, it can solo through Round 90, making it a good choice to use in Impoppable mode if the player can afford it.
 * If you're facing DDTs, it is best to combine the Flying Fortress with a x/2/x Monkey Village to counter the DDTs.
 * Combining Flying Fortress with a maximized Ultraboost and Permanent Brew allows it to create complete doom for the bloons. Besides Sun Temples and True Sun God, Flying Fortress is by far a superior choice for maximizing attack speed bonuses.
 * Slowing down DDTs via Bloon Sabotage or MOAB Glue can help make Flying Fortress have an easier time hitting DDTs accurately.

Trivia

 * Excluding Paragons, Flying Fortress is the sixth-most expensive upgrade alone, followed by The Anti-Bloon, Ultraboost, Super Mines, Legend of the Night, and True Sun God. This does not include the special variant of True Sun God, Vengeful True Sun God.
 * If including Paragons, in this case Apex Plasma Master, Glaive Dominus, Navarch of the Seas and Ascended Shadow, Flying Fortress is the tenth-most expensive upgrade alone, with the four Paragons coming at 4th, 3rd, 2nd, and 1st respectively.
 * Like a multitude of other fast-shooting towers, this tower easily misses single fast-moving bloons despite excelling against much stronger bloons especially due to its awkward targeting.
 * Spectre bombs cannot pop DDTs, unlike the upgrade in Bloons Monkey City. The Flying Fortress can, however.
 * A 0-2-5 Flying Fortress will defeat a B.A.D. by itself on Logs and Cubism, but a 2/0/5 plus any Camo detection will be more effective.
 * Unlocking all upgrades along Monkey Ace's Path 3 towards Flying Fortress requires less XP than unlocking all upgrades along Ninja Monkey's Path 1 towards Grandmaster Ninja.
 * The Flying Fortress in-game has a blue-and-red target symbol on each side of the wing, but the official artwork does not. The Instamonkey icon for it does, however.
 * There are ten blue window panes on the front of the Flying Fortress. All ten of these can be seen in the front view of the Flying Fortress when seen in-game.
 * Some players refer to the Flying Fortress as "Big Plane", named after the Flying Fortress's official description, or as the "ISAB Plane", named so because of how ISAB's YouTube channel logo updated for BTD6 features a Flying Fortress.
 * Before ISAB updated his YouTube channel logo approximately starting from around when he uploaded his first Flying Fortress video, his old profile image was a Spectre from BTD5 Flash. Interestingly, the Spectre is the upgrade before Flying Fortress, which implied that ISAB wanted to "upgrade" his old channel logo for BTD6.

Balance changes

 * In Version 4.0, the Spectre was nerfed in attack speed, but the Flying Fortress remained unchanged, indirectly buffing this upgrade.
 * Before version 2.0, there was a bug such that there would only be 2 streams of darts and bombs if the Flying Fortress is placed under a village. This did not seem to affect its popping power though.

Community achievements

 * Various challenges have been done for Flying Fortress on CHIMPS Mode, starting off with attempting to afford Flying Fortress in CHIMPS Mode. Although it was surely affordable in CHIMPS Mode throughout all updates, it was not achieved until Version 18.0, with the release of Admiral Brickell.
 * Prior to Version 22.0 price buffs to the Flying Fortress, players had attempted to win CHIMPS Mode with a Flying Fortress; until Version 18.0 it was impossible, because a 0-0-4 Spectre plus a low-cost defense was unable to beat late-game on its own. There were only two maps where a Flying Fortress was affordable on CHIMPS until Version 22.0.
 * However, this Reddit link reveals that it is possible to beat CHIMPS while at the same time owning a purchased Flying Fortress, but only in Version 18.0 with Admiral Brickell and her old leveling curve, a 0-0-0 Dart Monkey, and a 2-4-0 Ground Zero. This was so far the only time it was done without money-related bugs.
 * The first completely non-bugged Flying Fortress on CHIMPS win was shown here and was shown on 27th July 2020. Again used Brickell, but this time without her XP leveling bug.
 * The Flying Fortress is possible to be purchased in CHIMPS Mode on Moon Landing as of Version 21.0, using 0-0-0 Alchemist, Etienne, and 2-3-0 Monkey Intelligence Bureau. This is possible because of buffs to Etienne on Version 21.0. It can be seen here.
 * This also makes this the first time a Flying Fortress can be purchased before starting Round 100.
 * Flying Fortress is possible to afford on Downstream CHIMPS, as shown here.
 * The earliest round Flying Fortress can be afforded in CHIMPS is near the end of Round 94, using a combo of Captain Churchill, 3-0-0 Submerge and Support, 0-1-2 Ice, and 1-0-4 Spectre. One minor bug fix, which previously prevented Captain Churchill from dealing damage if both the shell and machine gun hit the same bloon, has helped reduce the total cost prior to Flying Fortress even further. This can be found here.
 * The first 2TC combo for the Flying Fortress without use of bugs is 0-2-5 Prince of Darkness + 1-0-5 Flying Fortress, on Version 22.0.
 * Flying Fortress is currently the most expensive tower capable of achieving 2MPC, and this was first achieved in Version 23.0 but only barely affording it before starting Round 100. Link.
 * On Resort, a combo of Sauda, 3-0-0 Submerge Sub, 2-0-2 Monkey Village, and 0-2-3 MOAB Glue can solo till Flying Fortress on CHIMPS, provided that the Glue Gunner and Monkey Ace are both fully discounted.

Cultural references

 * The name of the Flying Fortress upgrade is based on the Boeing B-17 Flying Fortress, although the aircraft's appearance is based primarily on the Soviet experimental aircraft Kalinin K-7, an aircraft design which was made in the 1930s.
 * It's also likely a reference to the Spectre's original upgrade description in BTD5: "Flying fortress of bloon doom."