This video was made possible by CuriosityStream, sign up for the Nebula bundle deal for just
15 dollars at curiositystream.com/realengineering to watch our logistics of close air support
video that inspired this episode.
Earlier this month I posed this question to my twitter followers. Was the P-47 Thunderbolt
one of the best planes of World War 2? And 35% of my audience said, no. So, in today’s
video I am going to explain why I disagree with 35% of my audience.
As we will see over the course of this video, the P-47 had it’s flaws, but by the time
the P-47D-25, easily identified by its distinctive bubble canopy, entered service in the spring
of 1944, the P-47, in my opinion, was an excellent plane that was instrumental to the success
of the Allied invasion of Europe.
The P-47s reputation may have been a victim of its image. It’s not sleek and aerodynamic
looking like the Spitfire or P-51 Mustang. It lacks the stylish gullwing of the F4U Corsair
and has never gained the infamy of the Stuka.
The plane is unusually….thicc? Seeing images of it’s crew standing next to their planes
really demonstrates how huge the fuselage was. The crew of this P-47 clearly agreed.
They painted the word chunky onto the engine cowl. But if you are like me, this should
indicate to you that there was something unique about the plane, that the designers tried
something different. The best way to illustrate this is through a size comparison.
This is the P-51 Mustang. It’s a streamlined, athletic looking plane...and this is the P-47.
You could have literally fit a P-51 inside the P-47 with room to spare. It simply doesn’t
look the part, but what if I told you it’s frame was purpose built to fit one incredibly
powerful supercharged engine.
Just as its namesake, the A-10 Thunderbolt II, was built around it’s gun, it’s ancestor
was built around it’s colossal engine. The massive Pratt and Whitney R-2800 Double Wasp.
A two row, 18 cylinder air-cooled radial engine with a massive displacement of 46 litres.
[1] The Merlin engine of the Spitfire and P-51 Mustang for comparison, one of the most
commonly used Allied engines of WW2, was 27 litres.
And this is just the powerplant, the P-47 was also fitted with a supercharger that took
up a significant volume of the aft fuselage, and this gave the P-47 some incredible high
altitude performance.
This shows the basic layout of the engine and supercharger inside the P-47 fuselage.
[2] The P-47 had a massive air intake just underneath the engine, big enough for a man
to fit in. The air from this intake was not immediately funnelled into the engine, instead
it was routed to the back of the plane first. Where it split into two ducts. One flowed
into a supercharger impeller, which compressed the air and returned it to the engine carburetor,
while the secondary duct flowed into an intercooler to cool the air from the compressor section
which had heated up as a result of the compression.
Ofcourse, this compressor section needed to be powered. This was done through hot energised
exhaust which was collected from the engine through this collection ring in a separate
duct system. This air was funnelled to a lower turbine section of the supercharger before
the hot exhaust was vented to the atmosphere here.
At lower altitudes less of this energised exhaust made it to the supercharger, as there
are two gated exhaust nozzles on either side of the plane that gradually closed as the
plane climbed in altitude.
This ensured the R-2800 double wasp was supplied with plenty of cold compressed air even at
27,000 feet, where other planes could not funnel enough of the oxygen needed to achieve
full engine power.
This wasn’t the only trick the P-47 had up it’s sleeve.
P-47D-4 variants and onward were fitted with a 30 gallon tank filled with an alcohol water
mixture located between the pilot and the engine in the firewall.
In times of emergency this mixture could be injected into the engine. This gave short
bursts of additional horsepower, taking the engine from it’s already massive 2,000 horsepower
to 2,300 horsepower.
So how does spraying water into an engine increase horsepower? The water isn’t fuel
and it displaces some air entering the engine surely. Your immediate thought would be that
this reduces horsepower. To boot, water is corrosive and incompressible, which could
cause some serious damage
Water injection increases horsepower in two ways. Both as a result of water’s cooling
effects. When water is injected into the engine it absorbs heat from the air and engine in
the process of evaporating. This increases engine pressure and lowers the temperature
of the piston. [3] Colder air is denser, and thus more air/fuel mixture is carried into
the piston with each stroke, increasing the energy released in each power stroke. The
evaporation also cools hotspots in the engine that can cause pre-ignition of the air-fuel
mixture. Meaning the air fuel mixture ignites before the piston is at the bottom of it’s
compression stroke and thus is working against the power strokes in the other cylinders,
lowering the power output of the engine.
The limited water supply meant this power boost was saved for emergency use only, but
emergencies are the exact time a little boost in horsepower is needed. Whether that is climbing
a little faster to regain an altitude advantage after a diving attack, taking off with a little
extra weight, or simply speeding away from an aggressor.
With all these design features, the P-47 was a fast plane with few planes being able to
match it’s high altitude performance. Early versions of the P-47 did suffer from poor
climb and turning performance. That massive engine added a great deal of weight, and by
virtue of the large fuselage needed to hold it, a great deal of parasitic drag too. In
order to climb or turn, the engine and wings needed to provide the force necessary to lift
the plane to higher altitude or shift it’s direction.
These characteristics did not affect the P-47s roll rate however, where it excelled thanks
to fantastic aileron control. [10] However, in a dog fight being outturned or out climbed
was a death sentence.
Climb rates were improved for the P-47D-22 and onward with the addition of a new larger
propellor, a 4 metre diameter propellor nicknamed the paddle prop. It had a longer chord and
distinctive cuffs which helped channel more air into the engine.
This new prop made the climb rate disadvantage marginal, surprising German pilots who had
become accustomed to pulling up sharply to evade P-47s. [1]
So the P-47, wasn’t the best out and out fighter. Surely that supercharger gave it
excellent high altitude performance, making it the perfect bomber escort. Yes and no,
because of another design flaw it’s range was lackluster.
The huge fuselage and engine made the P-47 a thirsty plane. It’s fuel tanks were always
going to struggle to feed this hungry engine. The plane could carry 305 gallons in two tanks
located around the cockpit. [4] The main L shaped tank located in front of and below
the pilot could hold 205 gallons, while the secondary tank located below and behind the
pilot could carry an additional 100 gallons.
These tanks gave the pilot between an hour and a half and 2 hours of flight time and
only just 50 extra miles of range over the spitfire, a notoriously short range fighter.
[5]
The spitfire was primarily designed as an interceptor to protect British Airspace, the
P-47 was not designed for this purpose and it’s lack of range frustrated bomber crews
who relied on it’s protection. The pilot’s of the Luftwaffe were perfectly aware of the
P-47’s range issues and often waited for the pilots to turn for home before launching
an attack.
All but the earliest production runs of P-47s could carry a drop tank on a belly hardpoint,
like this P-47D flying with a 75 gallon drop tank, which would have increased it’s range
by 180 kilometres. However plumping, hard points, and wing reinforcement to allow for
wing mounted drop tanks were added insultingly late with the P-47D-15. [6] This allowed the
P-47 to carry 108 gallon drop tanks on each wing, increasing the operational range by
380 kilometres. Allowing P-47s to reach as far as Frankfurt and Hamburg.
These tanks of course affect the plane's performance, pushing weight outwards decreases the planes
roll rate significantly, but they could be jettisoned if needed during a dog fight. This
was not an ideal solution, and the P-51 Mustang was without a doubt a better escort and fighter
plane.
However, the P-47 shined elsewhere. Those hardpoints were not exclusively designed to
carry external fuel tanks, they were designed for weapons and the P-47 could carry an impressive
payload. The P-51 Mustang had a max payload of 450
kg across it’s two wing-mounted hardpoints and had 6 M2 machine guns with 1840 rounds.
The P-47 in comparison could carry over twice the weight in bombs at 1,136 kilograms with
4 M2 heavy machine guns in each wing. [7] The guns were staggered like this to allow
side loading from each of their 350 round magazines. The P-47 was easily the heaviest
hitting single engine fighter of world war 2, and it could take a hit too.
The plane was affectionately nicknamed “The Jug”, short for Juggernaut, and for good
reason. Durability is a difficult thing to quantify, and it’s hard to parse out survivor
bias, but just like the A-10, photos of surviving planes tell a story. If you were crash landing
in any fighter in WW2, you would want it to be the P-47. There are countless photos of
P-47 crash landings where the pilot lived to tell the tale. All that ducting around
the pilot provided cushioning from the impact, and the smooth belly of the aircraft, free
from air scoops and other protrusions, minimized the risk of turnovers, which could crush and
kill the pilot, or simply trap them inside the plane.
The P-47 could take a lot of damage and keep flying. The liquid cooled Merlin engines of
the P-51 Mustang were not known for their ability to take a hit, but the air cooled
R-2800 double wasp radial engines were. The structure of the P-47 wings was incredibly
durable and could stay intact with severe damage. The ducting for the supercharger provided
some protection from bullets, and did not cause catastrophic failure with a few bullet
holes resulting in a drop in supercharger pressure, which at worst required the pilot
to drop in altitude and lower power. The fuel tanks under the pilot were self sealing and
offered good protection from hits on the belly of the plane and the pilot had two armored
plates behind and infront of the cock-pit.
So, we have listed the P-47s disadvantages, how they were minimized and it’s advantages.
What’s my rationale for saying it was one of the best planes of world war 2?
People who learn their history from video games will bash the P-47 for it’s slight
disadvantage in dogfighting, which is true enough, but it disregards the brain of the
pilot. The P-47 had it’s disadvantages in a dogfight, but it’s advantages are what
the pilots were trained to use and they were trained well. Why engage in a dogfight when
you have an altitude and speed advantage. The P-47 was the perfect hit and run fighter.
Striking from above, often catching the enemy unaware, and using it’s speed advantage
to escape.
They were most certainly capable of dispatching ME 109s and FW 190s, as proven by countless
flight reports from pilots. [8]
ME 109s could most certainly out turn a single P-47, but out turning 2 or 3 was an insurmountable
challenge, which was the challenge the Luftwaffe were met with as soon as the manufacturing
prowess of the United States entered the European Theatre. The P-47 was like the M4 Sherman
of the air, perhaps not the best vehicle on paper, but it got the job done and was there
when you needed it.
It was also the United States Air Force’s best fighter bomber. This plane was the warthog
of WW2. With the Luftwaffe threat all but vanquished by D-Day, the P-47 truly shined
in Normandy. Becoming a feared bird of prey over Europe.
The Allies quickly constructed advanced landing grounds in Normandy to create forward operating
bases for their air forces, like St. Pierre Du Mont located to the West of Omaha Beach.
What was once a farmer’s field became fully operational airfield just 12 days after d-day
with access roads, fuel dumps, ammo depots and a 1500 metre long track surfaced in steel
square mesh track. These advanced landing grounds gave even the shortest range fighter
aircraft the ability to loiter in the air over Normandy and push deeper into German
territory than before. At this stage of the war the Luftwaffe threat was all but eliminated.
In this battlefield the P-47 was in its prime. St Pierre Du Mont was home to 344th fighter
group flying P-47s and they helped rack up the P-47s astonishing destruction record.
From D-Day to VE Day, 336 days in total, the P-47 is credited with destroying 86,000 railway
cars, 9,000 locomotives, 6,000 armored fighting vehicles and 68,000 trucks. [9] This plane
played a vital role in the success of the Allied invasion, terrorising German troops
attempting to supply the front line with dive bombing attacks and strafing runs with it’s
fearsome M2 heavy machine guns.
Overall, the P-47 was a great all round aircraft. Like the M4 Sherman it was not perfect and
had it’s weaknesses, but it’s weaknesses were a direct consequence of its strengths.
The P-47 was a sturdy reliable plane that kept their pilots alive with plenty of firepower
and tactical advantages to get the job done. A plane loved by pilots and the ancestor of
the iconic A-10 Thunderbolt, who doubled down on the P-47s strengths, creating a plane dedicated
to the close air support role.
The role of close air support played a vital part in the Allied Invasion of Europe. The
constant harassment German troops had to contend with while attempting to travel to Normandy
delayed and blunted many of their counter offensives. I made an entire video on the
logistics of building the advanced airfields mentioned earlier, which is available now
on Nebula.
Nebula is a streaming platform I created with a collection of over one hundred fellow educational
YouTube creators. This platform has opened an entirely new avenue for creation for us.
Unshackling our creative process from the YouTube algorithm. The Logistics of D-Day
series is written without tip toeing around the realities of war. It’s a series we can
take our time producing. That time affords us the space to work on high quality animations
and ensure every episode is crammed with obscure and accurate detail on a side of war that
is rarely documented. The lessons and skills we are learning while making this series has
even impacted the content we upload here. With the 3D animations of this video being
a direct result of new skill sets we developed with the time and funding afforded to us for
this series.
I am just one of many channels you will be supporting in this way by signing up. Wendover
Production, Mustard and The Great War each have their own fantastic Originals. We have
partnered with Curiositystream to give you the insane bundle deal of CuriosityStream
and Nebula access for just 19.99 a year. Infact, we are currently running a limited time 26%
discount, so you can get both for just 14.79 a year, if you sign up with the link in description
today.
For that price you get access to all these fantastic Originals from your favourite YouTubers
and access to award winning documentaries from some of the world’s best filmmakers,
like this hour long documentary about the weird and astonishming miracle machines that
came out of Nazi Germany in the final years of the war.
As always, thanks for watching and thank you to all our patreon supports. If you would
like to see more from me, the links to my twitter, instagram, discord server and subreddit
are below.