Monkey Knowledge
Airforce Upgrades
Airforce Upgrades in BTD6: tier 3+ Monkey Aces and Heli Pilots get +1 pierce per shot. What changed in v41 and whether it is worth it.
Monkey Ace and Heli Pilot get +1 pierce per shot.
Guide
Airforce Upgrades is a first-row Military knowledge that gives +1 pierce to the projectiles of Monkey Aces and Heli Pilots that have at least one tier 3 upgrade. It has no prerequisite, costs one Knowledge Point, and unlocks Accelerated Aerodarts and Rapid Razors.
The tier 3 restriction was added in version 41. Before that it affected every Ace and Heli, which made base Ace openings in Races much stronger. Older guides that say "base Ace dart pierce 5 to 6" describe the pre-41 behaviour.
How it changes the game
Aces and Helis fire a lot of projectiles, so +1 pierce on each adds up once the tower qualifies:
- Monkey Ace tier 3+: Bomber Ace, Fighter Plane and Neva-Miss Targeting, and everything above them, get +1 per projectile. Bomber Ace is the cheapest tier 3 Ace and gets slightly more reliable at popping groups.
- Heli Pilot tier 3+: Razor Rotors, Apache Dartship, Downdraft and Support Chinook builds, and higher tiers, gain +1 per dart. Razor Rotors is the cheapest tier 3 Heli.
- Paragon: the Goliath Doomship's projectiles get the bonus too.
Some attacks are excluded: Downdraft's blowback, the Marine from Special Poperations and the mini-Comanches from Comanche Defense and Comanche Commander. Aces and Helis at tier 0 to 2 get nothing, and the knowledge adds no damage.
Is it worth it?
Priority: good. The effect is smaller than Naval Upgrades because cheap early Aces and Helis no longer benefit. For mid and late-game air builds it is still a free, permanent pierce buff on high-volume towers.
Its main value is the branch it opens. Accelerated Aerodarts leads to Targeted Pineapples, Gun Coolant, Aeronautic Subsidy and Advanced Logistics, while Rapid Razors leads to Charged Chinooks and Door Gunner. Advanced Logistics alone makes Airforce Upgrades a point every account eventually buys.
If you open with a cheap Ace in a Race, remember that the bonus only starts once the Ace reaches tier 3, so plan your first upgrades with that in mind.
Where it works
Airforce Upgrades is active wherever Monkey Knowledge is enabled: Standard games, Impoppable, Military Only, Races and Boss Events. It is disabled in CHIMPS and in challenges that switch knowledge off.
Frequently asked questions
Does Airforce Upgrades affect a base Monkey Ace?
No. Since version 41, only Aces and Helis with a tier 3 or higher upgrade get +1 pierce.
What is the cheapest tower that benefits?
A Bomber Ace for the Monkey Ace, and Razor Rotors for the Heli Pilot.
Does Airforce Upgrades affect the Goliath Doomship?
Yes. The Monkey Ace Paragon's projectiles get +1 pierce.
Which Heli attacks are excluded?
Downdraft's blowback, Special Poperations' Marine and the mini-Comanches.
Is Airforce Upgrades worth a point?
Yes, mainly because it leads to Advanced Logistics and the Heli Pilot nodes.

