Great Moments in GM Marketing: The XP-75

Jack Baruth
by Jack Baruth

Facing tough German competition, the people at General Motors come up with a large-displacement supercharged contender that outpowers but also out-weighs the BMW-and-Benz-powered entries. The look of their new model is controversial, but we’re told that it has to be that way due to existing platform constraints. And, of course, they’ll need a massive cash injection from the United States Government to make the whole thing happen, and they’ll get it, even though the aforementioned government wants them to build something completely different.

Wait a minute. Did you think I was talking about the CTS-V? Pas du tout! Set the wayback machine for the big band era, and let’s hear a story about how General Motors (allegedly) sabotaged the strategic plans of the United States in order to further their own economic interests.

The story goes like this: The year was 1942. While the man on the street still fretted and fussed about victory over the Japanese, and plenty of those men on the street would yet leave the street and return in zippered canvas bags, the men who ran the country could read production charts and they knew the war was as good as won. Sure, a lot of people would have to die in the realization of said victory, but in the long run the Japanese could build maybe one tank or bomber or aircraft carrier for every ten the Arsenal of Democracy could crank out. The smart money and the long-term thinkers were already considering the much more important war for market share after the shooting war ended in 1948 or thereabouts.

With that in mind, the War Department’s order that GM retool the Fisher Body facilities to focus on B-29 Superfortress production seemed unnecessary. GM didn’t plan to be in the plane business after the war. It would be better to leave the plants as they were, building B-29 nacelles in makeshift locations. Meanwhile, the bulk of the tooling slumbered, waiting for the future when steel-bodied cars, not aluminum-bodied aircraft, would be the product in demand. And yet GM wasn’t quite in the position to refuse the government’s demand. Only something more important than the B-29, which was pretty damn important and had taken almost as much time and money to engineer as the atomic bomb, could stand between GM and a very annoying bit of reconfiguration.

Enter the XP-75 “Eagle”. The idea behind the Eagle can be summarized as follows: Jet fighters? Yeah, man, they’re, totally, like, not ever gonna work. In order to win this war, we will need the fastest, highest-powered, piston-engined aircraft possible. So we’re gonna put two V-12 engines together, dude, and we’re, like, gonna supercharge ’em, and then we’ll stuff the whole thing in a fighter plane. But check this, bro, the airplane is totally gonna be made up of parts of other airplanes, so we don’t have to design anything new!

The fifty-six-liter Allison V-3420 consisted of a pair of Allison V-12s put together to produce 2,600 horsepower. Kind of like the way Aston Martin created that ultra-exclusive V-12 of theirs out of two Ford Taurus Duratecs. Originally intended as a makeshift engine for B-29s just in case the advanced radial engine that was under development failed to arrive in time, the V-3420 had very little reason to exist in an world that already recognized jet power as the propulsion unit of the future. To put this whole thing in perspective, the XP-75 Eagle and the Lockheed P-80 Shooting Star, which was the country’s first jet-powered fighter, were developed pretty much at the same time. Still, the V-3420 already existed, which meant it was tailor-made for GM’s purposes. More importantly, tooling for the V-3420 could be paid for by the War Department, and after the war that same tooling could be used to build cars. What a great idea! Instead of being stuck with an airplane factory after the war, the General could build an additional engine plant on the public dime!

The XP-75 itself was designed in-house by GM. A hodgepodge described by Wikipedia as “the outer wing panels from the North American P-51 Mustang, the tail assembly from the Douglas A-24 (SBD), and the undercarriage from the Vought F4U Corsair in a general layout much as in the Bell P-39 Airacobra,” the XP-75 was revised during early prototyping to use the cheaper and simpler wings from the P-40 Warhawk. The amount of unique engineering required to design this plane was presumably much less than it took to make the Buick Verano out of the Daewoo Lacetti.

The GM public-relations machine took the case for the XP-75 to the American people, who to a man were singularly ignorant of what jet power would mean for the skies of 1946, and the government acquiesced to their ideas with predictable rapidity. The B-29 project was denied the use of additional Fisher Body facilities, those facilities being earmarked for Allison V-3420 and XP-75 production. The stage was set for the XP-75 “Eagle” to be an all-American rip-roaring success.

Or not. While it’s documented in several sources that the purpose of the XP-75 was to spare GM from doing B-29 production, the assertion I’m about to make is a step beyond that and is entirely my own theory. I would suggest that the GM honchos never wanted the XP-75 to succeed. After all, full XP-75 production would still have been an annoyance for GM, even if it would have been considerably less troubling than building B-29s. The best thing that could have happened would have been for the XP-75 to fail spectacularly at government expense, leaving the plant idle.

And that is, indeed, what happened. In flight tests, the XP-75 understeered at the limit like whoa. The fit and finish was reprehensible. It weighed too much, consumed too much fuel, and didn’t appear to be durable. In short, it was a typical GM product (wink, wink). In 1944, the project was canceled and production facilities designated for the XP-75 were not reassigned. The War Department paid GM nine million bucks (about $120M today, or the price of four thousand new base-model Cadillacs of the era) for the dozen or so planes that were completed.

It’s possible, of course, that the above story is completely unfair to the General Motors leadership of the era. The XP-75 may have been a good-faith effort that simply failed to compete effectively, like the current-generation Malibu or the new Impala. In any event, the war ended ahead of schedule, the B-29s that would have been produced by Fisher were never truly necessary, and as Bob Dylan famously sang, everybody was forgiven and became friends. The ungainly Eagle itself has a kind of odd musclecar sexiness to it. Can’t you just imagine a group of them taking off from an airfield near San Francisco, gleaming aluminum and twenty-four cylinders of majestic power, roaring into the clouds to face long-range bombers from Japan? Ringing the airspeed indicators to five hundred miles per hour, the C5 Z06es of their day, charismatic, flawed, and visceral? It’s a lovely thing to consider. It’s as American as a CTS-V chasing down 911s around the Nurburgring, huh?

Jack Baruth
Jack Baruth

More by Jack Baruth

Comments
Join the conversation
2 of 129 comments
  • Wmba Wmba on Mar 30, 2013

    I rate this article on a par with some of Baruth's previous LLN stories which have been reprinted over the years in TTAC. Enthusiastic but wide of the mark simply because it is his personal summary of history, that is, what makes sense to him. Not necessarily what actually happened. Of course, it's also fun to take a rise out of the perpetually apoplectic GM boosters, full of high blood pressure about to burst their veins who have already forgotten the bankruptcy, and press us to believe TTAC is VW Central Marketing. So there's that. And then a whole pile of bleating follows in the comments like the people who think that engineers back before WWII were folk blindly groping along in the technical dark, clasping sliderules to light the way. Gosh, Math wasn't even invented! How did those guys build the Golden Gate Bridge without CAD? The real question is, how do present day guys build stuff with only a faint idea of the principles involved? All they know is how to turn the workstations on. I speak as a recently retired engineer, so take my outlook on things for what it's worth. Hopefully, there will be enough brainy folks left as time goes on to translate principles into computer programs that are actually accurate, so that the average technical drone can design useful things that work. The XP 75 was a typical WWII project. No time to genuflect, you gotta get a move on. Some projects work out, some don't. Recognize the failures and get on with something that does work. Recriminations happen years later when all sorts of conspiracy theories are dreamed up by people with an axe to grind, but little knowledge of what it was like to live through the sharp end. I would be highly surprised if GM management tried to actively fiddle with war production for their stockholders' benefit. The guys Roosevelt had running things tended to walk right over the but-what-if guys, and if they persisted had their balls for bookends. Quite right, too. The war needed winning.

  • Zackman Zackman on Jun 01, 2015

    After all is said and done, I still love GM.

  • CanadaCraig You can just imagine how quickly the tires are going to wear out on a 5,800 lbs AWD 2024 Dodge Charger.
  • Luke42 I tried FSD for a month in December 2022 on my Model Y and wasn’t impressed.The building-blocks were amazing but sum of the all of those amazing parts was about as useful as Honda Sensing in terms of reducing the driver’s workload.I have a list of fixes I need to see in Autopilot before I blow another $200 renting FSD. But I will try it for free for a month.I would love it if FSD v12 lived up to the hype and my mind were changed. But I have no reason to believe I might be wrong at this point, based on the reviews I’ve read so far. [shrug]. I’m sure I’ll have more to say about it once I get to test it.
  • FormerFF We bought three new and one used car last year, so we won't be visiting any showrooms this year unless a meteor hits one of them. Sorry to hear that Mini has terminated the manual transmission, a Mini could be a fun car to drive with a stick.It appears that 2025 is going to see a significant decrease in the number of models that can be had with a stick. The used car we bought is a Mk 7 GTI with a six speed manual, and my younger daughter and I are enjoying it quite a lot. We'll be hanging on to it for many years.
  • Oberkanone Where is the value here? Magna is assembling the vehicles. The IP is not novel. Just buy the IP at bankruptcy stage for next to nothing.
  • Jalop1991 what, no Turbo trim?
Next