The Great B-17 – B-24 Controversy

Yes, each plane is good – but very different in design philosophy and how they came about.

The Question

Which is better? The B-17 Flying Fortress designed by Boeing or the Consolidated B-24 Liberator?

This question often comes up at meetings, discussion boards, and other locations where aircraft oriented people gather and talk about history, tactics, and flying characteristics of planes.

Each plane is different - but considering all the Hollywood movies ever made about the air combat during the Second World war the B-17 is the most well known. This is due to many fortuitous happenings for the Boeing aircraft:

• It was the first well known bomber in combat -- in the Philippines.
• "The Memphis Belle" propaganda movie made in 1943 had only B-17s in it.
• The only deep offensive method to hit Germany was with the4 heavy bomber and that mean the B-17. Military politics ensured that the message was always in the public news.
• Not until mid 1943 did enough B-24s get to the UK to fly missions (and the first dozen or so flown were diversions due to 'teething problems' that all planes go through).
• Not Until the August 1, 1943 "Tidalwave" low level Ploesti oil refinery mission did the B-24s get any real press. However it was not sustained - there were not many press corps personnel in Africa. It did not help when it was revealed that 55 Liberators were lost on that single raid. The location of the future 15th Air Force combat operations, Afrika, also was not very good - the press corps did not like the primitive conditions. The happier the press was the better the press reports were. Based on their reports, the press did not like Africa much.

Background about “Common Knowledge”

When you consider that almost EVERY Hollywood movie ever has the B-17 as the star (one exception is “Sole Survivor” with Richard Basehart based upon the “Lady Be Good” B-24 discovered in Libya in 1956) the Flying Fortress is the most well known World War II bomber to the worldwide public. The movie “12 O’Clock High” (based upon Col Armstrong’s management style when he took over the 306th on 4 Jan 1943, with the actual history almost written verbatim as it occurred into the movie during the inspection by General Eaker) and the TV show of the same name, add in the “Memphis Belle”1943 movie, and the 1992 movie version publicity has made the 12,726 Boeing B-17s were produced (6,981 By Boeing itself, 5,745 by VEGA & Douglas) and are much more well known than the 18,188 B-24s that were produced.

The press corps in England also got off to a bad start with B-24s. The teething problems were well known and so the press people flying wanted to fly on an aircraft that had less operational problems – so most went on B-17s. It did not help that the first few times that a non-military War Correspondent flew in a B-24 Group to targets which were also being visited by B-17s the B-24 they were in was shot down and they were killed or captured. Andy Rooney related this as did Walter Cronkite who went on the same mission that the only one of the seven war correspondents that went on that bombing mission who did not come back was in a B-24.

This ties into the the private / public nature of the press. Each reporter had to be approved - and the military only wanted so many so that they were easier to censor the storeis. Now if a press person had a choice of going to England - beer, women, high level command ranks to talk with, and easy access to the men fighting, or going to a dusty desert where there is none of that - and at the end of the supply chain - they naturally choose England. Most were in England.

The local MILITARY press person did a lot of work to let people know what was going on - but all THEIR articles were at the mercy of the private firms to publish and centered around the individuals. Most of their stories ended up were in the local papers. Also, the military people had the disadvantage of only seeing their bit of the world - they were not allowed to roam and talk to many different groups.

The Planes

Different planes can be designed for same purpose but with different philosophies. Look at the number of different fighters produced (over 150 different types by all sides). All had the same purpose - shoot down the enemy planes.

Heavy bombers are less numerous in number of designs created in Germany, Russia, France, England and the USA - but all show the same design traits (except the Avro Lancaster and Boeing B-29).

B-17 & B-24 Design Goals

Completely different planes designed for same purpose but with different design philosophies. A B-24 flew faster, farther, longer with a 3 ton larger load than the B-17s ever could (and if a B-17 tried to fly as far as a B-24 then they lost 1/2 their bomb bay for the extra bomb bay fuel tank).

The B-17

The B-17 was developed out of the first world war and the military theory developed from Germany's use of the 4 engined Gotha bombers. It was stated by the leading air war theorists in the world - Lord Trenchard in Britain and Gen. Giulio Douhet of Italy - and believed by all - that the heavy bomber would be always get through and be able to destroy the enemy factories, cities - people - and bring any war to a quick conclusion. The H.G. Wells movie "Things to Come" is centered around this premise.

Boeing company came up with a design - using 1932 technology - to take a 1 1/2 tonne load over 400 miles to a target and return. The extreme distance was necessitated by the oceans around the USA. Other nations never thought of designs with this type of range (except Russia). The bombers were being built to fly out and sink enemy ships before they could get close to the USA.

The B-17 design team then had to use a wing that would lift a LOT of weight on what horsepower available - and that mean a thick wing that generates a LOT of lift - but the top speed is sacrificed for that lift. This was of no concern since they would be flying from the protection of the mainland so it did not matter. Not enough enemy fighters could be around from enemy carriers and the original 11 .50 caliber guns would easily defend off a plane attacking with just four .30 caliber machine guns that fighters had on them at the start of the design.

The B-17 wing is a pre-war era design and is THICK for heavy lift efficiency. The power of the engines available dictated this thick wing design. The wing is a lot like those found on C-152 Cessna. And like that wing – you cannot get a lot of speed due to heavy drag it causes. B-17s flew at 155 indicated in formation while B-24s flew at 165 indicated.

The B-17 also was designed during an era when air racing and aircraft design was rapidly evolving. One main feature of most every air racing plane during the 1930 (and private planes too) was they all had rounded wings. Part of this was the handling characteristics that an round edged wing provides but just by their function they also LOOK GOOD.

The B-17 flew flew on July 28, 1935.

The B-24

A Two Week Design

The Davis Wing

“Early in January, 1939 Fleet called designer Frank W. Fink into his office and told him they had decided to build a better bomber than Boeing's B-17. They informed Fink that he was to be project engineer for the new design and that a wooden mockup was to be ready in two weeks. When Fink asked what the new bomber looked like, he was told that this was to be a completely new project and the design hadn't even reached the basic drawing stage. He was then given a quick description of the new bomber - he would use the Model 31's Davis wing, its twin tail, four engine nacelles from the PBY Catalina and he would design a new fuselage with two bomb bays, each as large as the bomb bay of the B-17. He had 14 days to create the mock up, while Fleet and Laddon went to Washington to sell the new bomber to the U.S. Army.”

From: http://www.fourays.org/features_2005/great_combat_aircraft/b_24/b24_1.htm

December 28, 1939 was the first flight for the B-24 prototype.

And you thought the 90 days to design and build a P-51 from drawing to first flight was fast.

The US Army after getting a look at the B-17, and with the chances of war in China and Europe likely, looked at the bomb load, the distance to targets in Germany, Japan, Italy, that would have to be hit to fulfill the theory of air victory, had asked the aviation industry for a plane that could carry even more bombs and fly farther than what the B-17 could achieve.

The design team choose a wing - the 'Davis' wing - that is thinner when compared to the B-17 but generates more lift. However, the plane is heavier and the plane has to fly faster to achieve takeoff speed and just in cruise.

However, the Davis wing on the Liberator creates an altitude design limit by using the efficient wing which limited its high altitude ceiling since it used the same horsepower as the Fortress - thus with a combat load it could not get to the same altitude as a B-17. The pre-war thick B-17 wing is more lift efficient at a slower speed in thinner air.

Formation Speeds

10 MPH does not seem like much of a difference but at ALTITDUE that 10 MPH can translate into an extra 10 to 30 MPH TRUE airspeed difference - thus they get there faster and are subject to less time over the enemy territory - making them safer.

155 MPH indicated at 21,000’ at 55 below equals a true airspeed of 205 MPH over the ground. Going at 165 MPH comes out to 220 MPH. So the B-24s are flying 15 MPH faster than a B-17 at the same altitude. The 10 MPH difference in formation cruise is the main reason why they never flew in the same combat formation. They tried it in 1943 and it was just too difficult. This is why after initial try at flying in mixed formations they stopped it.

This often meant the B-24s could take off later, fly the same distance to bomb a target, and were already on the ground before the 17s ever got back to the English shore.

Functionality

The B-24 design is very war functional. It gives what the pre-war planners wanted: a long range heavy load bomber. This functionality does come at a price. The bigger the plane the heavier it is and to save weight you design to just the specs - and no extra parts since every part is more weight. The thinner wing by 1930 design standards means a less strong wing. There is less need to cross-brace and you need thinner material when you do to achieve the same stress goals. The B-17 being a thicker wing needed more - stronger - material to support the wing and thus had to be designed stronger. So in combat this helped the B-17.

The Loss Rate

All loss rates are miss-leading. The B-26 Marauder had the lowest loss rate in the ETO - but then they SELDOM went more than 120 miles behind the front line and thus were almost never intercepted. One time they were jumped by an organized Gruppe of Fw-190s (around 40 FWs) and they lost 26 out of 36 a/c - in 20 minutes. This was during the Battle of the Bulge.

As a percentage by mission there is almost no difference in the loss rate between B-24s and B-17s in the same timeframe. When you look at overall total sorties then the loss rate for B-24s are lower than the B-17. This occurs since from 1944 onwards there were twice as many B-24s flying than B-17s and so the sheer numbers skew the overall WW II ETO percentage downwards.

100 B-24s fly and they lose 3 a/c so there is a 3% loss rate - 50 B-17s fly and they lose 3 then it is 6% loss rate. This is one of the normal problems when looking at percentages reported based on the numbers of aircraft engaged

The B-24 really started arriving en-masse in the spring and summer of 1944. By then most of the problems with the B-24 had been corrected but some design problems would always remain. Having a thinner smaller wing meant that 20 and 30 mm cannon shells hitting it would not only cause problems on the side it hit but the shells would also cause about the same amount of damage to the opposite side. It also meant that a few shells in the smaller wing cross section would cause the wing to fail faster than the much longer chord, and thicker, B-17 wing. Other areas of the plane – being bigger and with twin rudders – meant that the B-24 could take some hits and not be affected – pretty much like the B-17. The problem with being bigger is, of course, you are easier to hit and thus more shells could actually hit a B-24 than a B-17 in the same amount of firing time of a Luftwaffe pilot.

Photographs

Beauty in the Eyes of the Beholder

Taking pictures of aircraft there are some angles that no matter what you do the photo almost always works. The B-24 presents a problem though: It is big. It sits on high tricycle landing gear arrangement so the photographer needs to get up 10 feet or so to get a good view (not always possible), it has a real thin wing that edge-on it disappears (does not give depth to the photograph), the plane is "boxy" so that means as a photographer you have to work harder to get better pictures. The war correspondent's goal was to tell a story using one photo.

The human mind likes curves. The B-17 is full of them. I talked to one army combat photographer from the 15th AF and he transferred out of flying in B-17s into B-24s due to the boxiness of the B-24: he could not take sharp photos through the curved glass of the B-17s - the B-24 glass is flat - no distortion = better photos! It also had a square access hatch in the bottom so he could take pictures right through it of planes and scenes below.

The Fortress is to the Spitfire like the Liberator is to the Hurricane.

A valid comparison of the B-17 and B-24 is like comparing the Spitfire and the Hurricane: there were more Hurricanes in the Battle of Britain and they shot down a higher percentage of Germans in combat that their deployed ratio would suggest (80% of planes shot down for 60% of total planes in combat) which mean that the Hurricanes should have gotten the lion share of the credit - but he Spits got all the press! They just looked better in a photograph.

There were more Hurricanes in the Battle of Britain and they shot down a higher percentage of Germans that their ratio would suggest than the Spitfires - but he Spits got all the press! They just looked better in flight and on the ground in photographs. The B-24 Liberator is treated the same way.

The B-24 Liberator is treated the same way.

The British

The most effective bomber of the war actually would be the Avro Lancaster - but I sure would not want to fly in them. 55,000 bomber command crew members were killed during the war - and often the whole crew would die in a Lancaster. This is due to the way the two emergency exits from the a/c were laid out. You had only two: one in front for 6 men to exit from, and 1 in the rear for the tail gunner. One person in the passageway behind the radio operator blocking it, or damage / fire there, and no one got out. Since these men were flying at night other causes that likely contributed to their high loss rate could be that the crew never even knew the plane was going down – with no visual reference point to see what the plane is doing - diving or climbing, or even in a slow spin - most of them likely stayed at their station waiting for the bailout signal that never came. (They had alarm bells and lights to signal the crew.)

Summary

The two U.S. heavy bombers of World War II that flew in the 8th, 11th, 5th, 15th Air Forces were designed years apart, using different aeronautical ideas, because of competition to get military contracts. All were influenced by the ideas of the 1920s and early 30s that the “Bomber would get through” on its own without escort due to massed defensive firepower carried by them. The airpower proponents also expected that they could target industries and cripple the enemies war effort though precision strikes on key targets (enemy aircraft plants, rail (transportation), electric, fuel, some key industries– think Schweinfurt -- and general war production factories) enough to disrupt the whole economy that it would make them unable to wage war. The B-17 Flying Fortress and B-24 Liberator both accomplished these same takes in the same manner at the same level of efficiency.