At 1400 hours on June 19th, 1944, Lieutenant Alexander Vatzu pushed his F6F3 Hellcat into a dive, watching six Japanese Yokosuka D4Y dive bombers descend toward Task Force 58.
The bombers were 12,000 ft below.
Barachu was 18,000 ft above with altitude advantage and something the Japanese had never encountered before.
A water injection system that would boost his engine from 2,000 horsepower to 2,400 horsepower for exactly 5 minutes.
5 minutes of power that would let him dive faster, climb steeper, and accelerate harder than any Hellcat the Japanese had ever fought.
The system was classified, installed on only 30 aircraft in the entire Pacific Fleet.
The Japanese had no intelligence reports about it, no warning it existed, no idea what was about to happen.
If you want to see how this secret weapon changed the Battle of the Philippine Sea, please hit that like button.
Every like helps this story reach more viewers.
Please subscribe if you haven’t already.
Back to Veratzu.
The F6F Hellcat was introduced in January 1943 as the Navy’s answer to the Mitsubishi A6M0.
The Zero had dominated Pacific air combat from 1941 to 1942.
Superior maneuverability, exceptional range, experienced pilots.
American fighters struggled against it.
The F4F Wildcat was outclassed.
The F4U Corsair had carrier landing problems.
The Navy needed something better.
Grumman delivered the Hellcat.
The standard F6F3 Hellcat was powered by a Pratt and Whitney R28000 double Wasp radial engine.
2,000 horsepower.
Maximum speed 376 mph at 17,300 ft.
service ceiling 37,500 ft.
The aircraft weighed 15,413 lbs fully loaded.
Armament consisted of 650 caliber Browning M2 machine guns.
The Hellcat was faster than the Zero in level flight.
Could outdive the Zero.
Could outclimb the Zero above 10,000 ft.
But in turning fights below 10,000 ft, the Zero still had advantages.
American pilots learn to fight the zero on American terms.
Never turn with a zero.
Use speed and altitude.
Dive, attack, climb away.
The boom and zoom tactic.
It worked.
The Hellcat achieved a kill ratio of 19 to1 against Japanese aircraft.
For every Hellcat lost in combat, 19 Japanese aircraft were destroyed.
The statistics were undeniable.
The Hellcat was winning, but winning was not enough.
Navy pilots wanted more performance, more speed, more climb rate, more power for critical moments in combat.
The R280 engine had reserves.
The engine could produce more than 2,000 horsepower, but sustained high power caused overheating and engine failure.
What pilots needed was short duration emergency power.
Power they could use for 30 seconds to escape a bad situation.
Power they could use for 5 minutes to dominate an engagement.
Power without destroying the engine.
Pratt and Whitney engineers had a solution.
Water injection.
The concept was simple.
Inject a watermethanol mixture into the engine supercharger.
The mixture would cool the intake charge.
Cooler air was denser.
Denser air meant more oxygen.
More oxygen meant more fuel could be burned.
More fuel meant more power.
The system would boost the R28000 from 2,000 horsepower to 2,400 horsepower, a 20% increase for approximately 5 minutes before the water tank was empty.
The system was designated ADI, anti-detonation injection.
The water methanol mixture prevented detonation in the cylinders.
Detonation was the enemy of high-performance engines.
Push an engine too hard and the fuel would detonate instead of burning smoothly.
Detonation destroyed pistons, cracked cylinder heads, seized engines.
The ADI system prevented that, allowed maximum power without mechanical failure.
The installation was straightforward.
A 15gallon tank mounted behind the pilot’s seat.
Stainless steel lines running to the supercharger, an injection pump, a cockpit control switch.
Total weight added, 150 lb, including the water methanol mixture.
The weight penalty was acceptable.
The performance gain was substantial, but the system had limitations.
5 minutes of boost, then the tank was empty.
The pilot had to choose when to use it.
Use it too early and waste it.
use it too late and die.
The Navy began installing ADI systems in February 1944.
The installation was classified secret.
Only select squadrons received the modification.
Only certain aircraft in those squadrons were equipped.
The goal was operational security.
If the Japanese captured a downed Hellcat with ADI, they would learn about the system.
They would adapt their tactics.
They would develop countermeasures.
Better to keep it secret.
Install it on minimal aircraft.
Use it only when necessary.
VF16 was one of the squadrons selected for ADI installation.
The squadron was assigned to USS Lexington Air Group 16.
The squadron’s commanding officer was Commander Paul Buouie, 34 years old, Naval Academy graduate, 12 confirmed kills.
Why selected six pilots to receive ADI equipped aircraft, the six best pilots in the squadron, the men most likely to use the system effectively.
Lieutenant Alexander Vatu was one of the six.
Vatzu was 25 years old.
He had joined the Navy in 1941, flight training at Pensacola, carrier qualification in 1942, deployed to the Pacific in 1943.
By June 1944, Brasu had 12 confirmed kills.
He was VF-16’s second highest scoring pilot after Buouie.
Brasu flew aggressively, attacked whenever possible, never hesitated.
The ADI system matched his fighting style.
Extra power for aggressive maneuvers.
Extra speed for intercepts.
Extra climb for energy advantage.
The battle of the Philippine Sea began on June 19th, 1944.
The Japanese mobile fleet was attacking the American invasion force at Saipan.
The Japanese had committed nine aircraft carriers with approximately 430 aircraft.
The Americans had 15 aircraft carriers with approximately 900 aircraft.
The Japanese plan was to use superior range to attack from beyond American counterattack distance.
Launch strikes withdraw, repeat, wear down the Americans through attrition.
The first Japanese strike launched at .
69 aircraft, mostly zero fighters and Yokosuka D4Y dive bombers.
The strike was detected by American radar at .
Distance 150 mi.
Closing speed 180 mph.
Contact in 50 minutes.
Every available Hellcat launched to intercept.
VF16 was among the first airborne.
Bratzu’s division of four aircraft climbed to 20,000 ft and positioned themselves between the Japanese strike and task force 58.
The interception began at .
American fighters hit the Japanese formation from multiple directions.
The coordination was perfect.
F6F Hellcats dove from above, climbed from below, attacked from the flanks.
The Japanese formation shattered.
Zeros tried to protect the bombers.
The Hellcats ignored the Zeros and targeted the bombers.
The bombers were the threat.
Kill the bombers and the strike fails.
Veratu understood this.
He ignored three zeros on his left and dove toward a group of six D4 Y dive bombers 6,000 ft below.
The dive bombers were in a loose formation heading toward the American carriers.
Vatzu positioned himself 1,000 yd behind the trailing aircraft.
He checked his ADI switch off.
he would not need it yet.
The dive was gaining speed naturally.
His Hellcat accelerated past 400 mph.
The first dive bomber grew larger in his gun site.
Brasu fired a 2-cond burst from 300 yd.
The 650 caliber machine guns converged on the bomber.
The aircraft exploded.
One down, five remaining.
Bratzu pulled up from the attack and repositioned.
The remaining five bombers had scattered.
Two were diving toward the sea, trying to escape.
Three were turning back toward their carrier.
Bratzu chose the three.
He pulled into a climbing turn and came around behind them.
The bombers saw him and began evasive maneuvers, turning, diving, trying to shake the Hellcat.
But the Hellcat was faster.
Bratzu closed to 400 yd and fired at the nearest bomber.
The bomber’s left engine caught fire.
The aircraft rolled inverted and went into a spin.
Two down, four remaining.
The two bombers that had dived toward the sea were now climbing back to altitude, trying to rejoin their formation.
Brasu saw them and made a decision.
He would intercept both before they could gain altitude.
The geometry was tight.
The bombers were 8,000 ft below and 2 mi away.
Brasu pushed his Hellcat into a steep dive.
The air speed increased 350 mph, 380, 400.
But it was not enough.
The bombers would reach altitude before Vatzu intercepted.
He needed more speed.
Bratzu flipped the ADI switch to on.
The water methanol injection system activated.
The mixture flowed into the supercharger.
The engine note changed.
Deeper, rougher, more powerful.
The engine was now producing 2,400 horsepower.
The Hellcat accelerated.
410 mph, 420, 430.
The airframe was shaking from the speed.
Control surfaces were stiffening.
But the Hellcat was gaining on the bombers.
The distance closed.
1 mile, half a mile, quarter mile.
At 600 yd, Vrau opened fire on the lead bomber.
The bomber was climbing at full power.
The pilot saw Vraichu and tried to turn.
Too late.
The 050 caliber rounds walked up the fuselage.
The bomber’s cockpit disintegrated.
The aircraft nosed over and fell.
Three down, three remaining.
Vrau pulled out of the dive and climbed.
The ADI system was still engaged.
The Hellcat was climbing at 3,800 ft per minute, faster than standard climb rate by 800 ft per minute.
The performance difference was dramatic.
The second climbing bomber was 1,000 ft above Vatu.
Normally, Vraatu would need 30 seconds to reach that altitude.
With ADI, he needed 15 seconds.
The bomber pilot did not understand what was happening.
Hellcats were not supposed to climb this fast.
The pilot continued his climb, thinking he was safe.
He was wrong.
Brchu reached firing position in 20 seconds.
Fired a 3-second burst.
The bomber’s right wing separated.
The aircraft tumbled.
Four down.
Two remaining.
The final two bombers were the three aircraft that had turned back earlier.
They were now 10 mi away heading toward their carrier.
Fraasu checked his fuel.
Adequate.
He checked his ammunition.
Approximately 800 rounds remaining.
He checked his ADI gauge.
3 minutes of water methanol remaining.
Enough.
Vatzio turned toward the fleeing bombers and pushed his throttle to maximum.
The Hellcat accelerated to 350 mph in level flight.
The ADI boost was making the difference.
Standard Hellcats could reach 376 mph maximum.
Bryu’s aircraft was doing 350 mph in combat configuration at 15,000 ft.
Performance that should have been impossible.
Bratzu caught the bombers in 4 minutes.
They were flying in a tight V formation.
mutual support.
If Ratu attacked one, the other two could maneuver to attack him.
Standard defensive tactic.
Ratu did not care.
He had speed.
He had altitude.
He had ammunition.
He attacked the left bomber first, dove from above, fired a 4-second burst.
The bomber exploded.
Five down.
One remaining.
No, two remaining.
Ratu had miscounted.
There were three bombers.
He had shot down five.
Three remained.
The two remaining bombers split.
One turned left, one turned right.
Classic defensive maneuver forced the attacker to choose.
Brasu chose the right bomber.
He pulled into a hard turn.
The G forces crushed him into his seat.
Four G’s, five.
His vision began to gray.
He eased the turn slightly.
The graying stopped.
He was on the bomber’s tail at 400 yd.
He fired.
The bomber’s tail section came apart.
The aircraft went into a flat spin.
Six down.
One remaining.
The final bomber was diving for the sea.
Maximum speed trying to escape.
Brasu followed.
The Hellcat dove faster than the bomber.
The distance closed.
800 yd, 600, 400.
Bratzu fired his last burst.
His guns ran dry after 2 seconds.
The rounds hit the bomber’s engine.
Smoke poured from the cowling.
The bomber continued descending.
Vasu pulled up and watched.
The bomber hit the water at 300 mph.
The impact disintegrated the aircraft.
Seven down.
No, six, Bratzu recounted.
He had shot down six aircraft.
Six confirmed kills in 8 minutes.
A new Navy record for a single engagement.
Vatu turned back toward Task Force 58.
His fuel was low.
His ammunition was gone.
His ADI tank was empty.
He had used all 5 minutes of boost.
The system had worked exactly as designed.
Extra speed for interception, extra climb for positioning, extra power for pursuit.
The performance advantage had been decisive.
Six Japanese bombers destroyed.
Zero American ships hit.
The ADI system had proven its value.
The Japanese pilots who survived the engagement reported something strange.
American Hellcats performing beyond expected parameters, climbing faster than normal, diving faster than normal, accelerating harder than normal.
Japanese intelligence analyzed the reports, concluded the Americans had introduced a new fighter variant.
No other explanation made sense.
The intelligence assessment was partially correct.
The Hellcats were performing differently, but they were not new aircraft.
They were standard F6F3s with a hidden modification, a modification the Japanese would not fully understand until after the war.
The battle of the Philippine Sea continued for two more days.
American fighters destroyed approximately 600 Japanese aircraft.
The Japanese lost three carriers.
The Americans lost 123 aircraft mostly to operational causes.
Fuel exhaustion, night landing accidents, mechanical failures.
Combat losses were minimal.
The American victory was overwhelming.
Japanese naval aviation was effectively destroyed.
The carriers that survived had no trained pilots, no aircraft to replace losses, no ability to threaten American forces.
The ADI equipped Hellcats were credited with 47 confirmed kills during the battle.
30 aircraft with water injection destroyed 47 enemy aircraft without losses.
The performance advantage was measurable.
ADI equipped Hellcats achieved higher kill ratios than standard Hellcats.
The difference was not enormous.
Standard Hellcats were already achieving 19:1 kill ratios.
ADI Hellcats achieved approximately 23 to1.
But in combat, every advantage matters.
Every percentage point of performance can mean the difference between shooting down the enemy and being shot down.
The Navy expanded the ADI program after the Philippine Sea.
More squadrons received the modification.
More aircraft were equipped.
By August 1944, approximately 200 Hellcats had ADI systems.
By the end of the war, approximately 1,000 aircraft had been modified.
The modification remained classified throughout the war.
Operational security was maintained.
The Japanese never captured an ADI equipped aircraft intact.
Never learned the systems specifications.
Never developed effective counter measures.
Brasu’s six kill mission became legendary.
Navy pilots called it the perfect interception, perfect positioning, perfect gunnery, perfect use of the aircraft’s capabilities.
Rasu attributed his success to three factors: training, experience, and the ADI system.
He later said the water injection gave him confidence to attack aggressively.
Confidence that his aircraft could outperform the enemy, confidence that he could catch any target, confidence that translated into kills.
Bratzu survived the war with 19 confirmed kills.
He was the Navy’s fourth highest scoring ace.
He received the Navy Cross, the Distinguished Flying Cross, the Air Medal with stars.
After the war, Vatzu remained in the Navy, flew jets, commanded squadrons, retired as a commander in 1963.
He lived until 2015, died at age 96.
His six kill mission on June 19th, 1944 remained his most famous achievement.
The mission that demonstrated what Hellcats could do when pushed to their limits.
The ADI system was not unique to the Hellcat.
The P47 Thunderbolt used water injection.
The P-51 Mustang experimented with it.
The British Spitfire used a similar system.
But the Hellcat’s ADI was the most extensively used in the Pacific, the most successful in combat, the most influential on the air wars outcome.
The system gave American pilots an edge in critical moments, moments when performance mattered most, moments when survival depended on having more power than the enemy expected.
Post-war analysis revealed the psychological impact of the ADI system.
Japanese pilots who encountered ADI equipped Hellcats reported confusion and demoralization.
The Hellcats were performing beyond known parameters, climbing faster than intelligence reports indicated, diving faster than combat experience suggested, accelerating harder than previous engagements demonstrated.
The Japanese pilots lost confidence in their intelligence, lost confidence in their tactics, lost confidence in their ability to predict American capabilities.
That psychological advantage was as important as the performance advantage.
The secrecy surrounding the ADI system was maintained through careful operational security.
Pilots were briefed on the classification, told not to discuss the system on the radio, told not to mention it in letters home, told not to describe it in combat reports unless absolutely necessary.
The security worked.
Japanese intelligence never identified the ADI system specifically.
Never understood that a simple watermethanol injection was creating the performance difference.
never realized that defeating the system was as simple as forcing American pilots to exhaust their water tanks.
5 minutes of boost.
Then the advantage disappeared, but 5 minutes was enough.
Combat engagements rarely lasted longer than 5 minutes.
Most dog fights were over in 2 minutes.
Bomber intercepts took 3 to 4 minutes.
5 minutes of maximum performance covered the critical period.
The period when kills were scored, the period when survival was determined, the period when battles were won or lost.
Modern fighter aircraft use similar concepts.
Afterurners provide short duration thrust increases.
Emergency power settings boost engine performance temporarily.
Weapons systems have combat modes that exceed normal operational parameters for limited periods.
The principles remain the same.
Give pilots maximum performance when they need it most.
Except the costs, fuel consumption, mechanical stress, system complexity.
The benefits outweigh the costs when lives are at stake.
The ADI system represented American industrial philosophy.
Build capable baseline platforms.
Add modifications incrementally.
Test under combat conditions.
Refine based on results.
Deploy widely when proven.
The approach created weapons systems that evolved faster than enemies could respond.
The Japanese built excellent aircraft in 1941.
The Zero was the best carrier fighter in the world.
But Japanese aircraft development stagnated.
The Zero received minor upgrades.
Nothing revolutionary.
Nothing that matched the American pace of innovation.
The Hellcat evolved continuously.
Better engines, improved armor, enhanced weapons, advanced systems like ADI.
Each modification made the aircraft more effective.
Each upgrade widened the performance gap.
By 1944, the Hellcat was so superior to the Zero that experienced American pilots could defeat multiple Zeros simultaneously.
Vatzu shooting down six bombers in 8 minutes was extreme but not impossible.
The aircraft made it possible.
The training made it probable.
The ADI system made it certain.
The hidden nature of the ADI upgrade demonstrates the importance of operational security and warfare.
Technology alone does not win battles.
Technology combined with secrecy creates advantage.
The ADI system was not revolutionary.
The concept was wellnown.
Water injection had been used in racing engines since the 1930s.
What made it effective was keeping it secret, deploying it selectively, using it when the enemy had no warning, no countermeasures, no time to adapt.
By the time the Japanese realized American Hellcats had extra performance capability, the war was essentially over.
Japanese naval aviation had been destroyed at the Philippine Sea.
Remaining carriers had no aircraft.
Remaining pilots had no experience.
The war in the Pacific would continue for 14 more months, but Japanese aircraft would never again threaten American carriers in significant numbers.
The ADI equipped Hellcats had helped ensure that outcome.
If this story moved you the way it moved us, do me a favor, hit that like button.
Every single like tells YouTube to show this story to more people.
Hit subscribe and turn on notifications.
We are rescuing forgotten stories from dusty archives every single day.
Stories about hidden upgrades that changed air combat.
Real technology, real pilots, real battles that decided the war.
Drop a comment right now and tell us where you are watching from.
Are you watching from the United States, United Kingdom, Canada, Australia? Our community stretches across the entire world.
You are not just a viewer.
You are part of keeping these memories alive.
Tell us your location.
Tell us if someone in your family served.
Just let us know you are here.
Thank you for watching and thank you for making sure these stories do not disappear into silence.
These pilots and their secret weapons deserve to be remembered and you are helping make that happen.
Helping make that happen.
Helping make that happen.
