# Why did WW2-era carrier aircraft tend to have radial engines? **URL:** \ **Category:** Factual Questions\ **Created:** [September 2, 2003, 5:38am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084 "2003-09-02T05:38:25Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Brutus](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@Brutus](https://boards.straightdope.com/u/Brutus)\ **Post date:** [September 2, 2003, 5:38am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/1 "2003-09-02T05:38:25Z")
I am in a bit of a WW2 aviation kick lately. Though I have known about the Hellcat, and Dauntless DB, and Corsair, and Avenger,etc, for some time, it just occured to me: They all have radial engines. As did the Zero and other carrier aircraft. Why? They only advantage I can think of is a potentially ‘shorter nose’, which must be nice for carrier deck handling. (One look at the Corsair seems to kill that theory, but…) What’s the scoop? Why didn’t the USN have any inlines on its carriers? ---
**Author:** ![detop](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@detop](https://boards.straightdope.com/u/detop)\ **Post date:** [September 2, 2003, 6:30am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/2 "2003-09-02T06:30:27Z")
The Brits did have a few inlines : [the Seafire](http://www.supermarine-spitfire.co.uk/supermarine_seafire.html) and [the Fairey Barracuda](http://www.fleetairarmarchive.net/Aircraft/Barracuda.htm) among others, but I think they were not as interested as the USN and the IJN about saving as much space as possible, because of their empire which allowed land-based plane coverage basically around the world. ---
**Author:** ![OttoDaFe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ottodafe/32/356_2.png) [@OttoDaFe](https://boards.straightdope.com/u/OttoDaFe)\ **Post date:** [September 2, 2003, 6:32am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/3 "2003-09-02T06:32:18Z")
Someone with far better credentials will be along presently, but in the meantime I’d say you’ve pretty much nailed it. Given the limited space on the flight deck (and more important, in the hangar), the short nose would be a positive trait. As for the Corsair, its long nose certainly caused problems for inexperienced pilots, and led to its being nicknamed the “Ensign Eliminator.” That, and the generally putrid deck-landing characteristics of the early variants, may well have been among the factors that led the Navy to prefer the Hellcat. One other thing—and here I’m gonna go out on a limb—while the air-cooled radial is not necessarily a _simpler_ piece of machinery than a water-cooled inline, it can be considered more _robust_. At least in the sense that there is no cooling system to be drained by a single bullet, leaving the pilot stranded 250 miles (statute or nautical, your pick) from home. Over water, which would be ironical as hell (“water, water, everywhere . . .”). But in this, as in so many other things, I am but a dilletante. As stated previously, please hold and an expert will be with you shortly. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [September 2, 2003, 6:41am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/4 "2003-09-02T06:41:15Z")
I think it had something to do with air cooling being less prone to damage from enemy fire than water cooled engines: [1932 Curtiss YA-10](http://www.wpafb.af.mil/museum/research/attack/a2/a2-11.htm) > [@](#): > > **The first YA-8 (S/N 32-344) was used to test the feasibility of producing a radial engine powered version of the Curtiss A-8. The liquid-cooled Curtiss “Conqueror” engine was removed and replaced with a Pratt & Whitney air-cooled radial engine. Because the liquid cooling system was extremely vulnerable to enemy fire, the Air Corps believed fitting air cooled engine would give the ground attack aircraft increased combat durability.** ---
**Author:** ![Boo\_Boo\_Foo](https://avatars.discourse-cdn.com/v4/letter/b/e274bd/32.png) [@Boo\_Boo\_Foo](https://boards.straightdope.com/u/Boo_Boo_Foo)\ **Post date:** [September 2, 2003, 6:52am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/5 "2003-09-02T06:52:47Z")
**ottoDaFe**? Your insight there is a very valid one indeed. Water cooled V12 aircraft were particularly prone to shrapnel hits - and the nature of the US Navy’s Pacific campaign was such that island hopping and stuff like that required a particularly robust sort of airplane - and the Corsair in particular fitted that role. If memory serves me correctly, the Corsair had a long nose because it featured the exact same engine out of a B29 Super Fortress - which I’m pretty sure was actually 4 radials deep. Hard to believe you could make a 4 radial deep aircooled engine that wouldn’t seize the pistons on the 4th radial - but they perfected it and made it quite a robust engine I’m told. I’m pretty sure that the Corsair was rated at 2,800 horsepower at maximum rpm - and I’m also pretty sure that was a normally aspirated engine - unlike the Thunderbolt which had a fuselage mounted turbocharger which ironically proved remarkably impervious to shrapnel hits. I remember reading once that the British actually perfected the art of landing a Corsair on a carrier deck and passed the knowledge on to their American allies. Apparently, because the nose was so long and with flaps down you really had bugger all vision of the deck upon approach to the deck, so the Brits perfected the art of coming in from a 30 degree angle and banking on to the deck in a slow consistent arc. This allowed the pilot to keep his eye on the carrier deck the whole way and it proved to be the safest way to land the plane apparently. The dihedral wings didn’t originally exist on the Corsair - but the first attempts at a carrier landing showed that the Prop was bottoming out - so the dihedrals were put into to lower the wheel landing mounts under maximum compression. ---
**Author:** ![Brutus](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@Brutus](https://boards.straightdope.com/u/Brutus)\ **Post date:** [September 2, 2003, 7:08am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/6 "2003-09-02T07:08:36Z")
…And my estimation of the bravery of WW2 pilots just went up yet another notch. Landing on a carrier, tricky enough, but then you couldn’t quite see it, and oh ya, your prop may scrape the deck. God bless 'em… Thanks for the answers. I didn’t consider the durability of the rotary vs. the inline, but it makes sense, and jibes with my _IL-2:Sturmovik_ experiences. **Boo Boo Foo** , I do also recall reading about the Brits and the Corsair. The US was giving them to land-based USMC squadrons, since the USN didn’t really care for them, until the Brits did their thing. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [September 2, 2003, 7:43am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/7 "2003-09-02T07:43:35Z")
> [@](#): > > \*Originally posted by Boo Boo Foo \* > \*\*[ > If memory serves me correctly the Corsair had a long nose because it featured the exact same engine out of a B29 Super Fortress - which I’m pretty sure was actually 4 radials deep. Hard to believe you could make a 4 radial deep aircooled engine that wouldn’t seize the pistons on the 4th radial - but they perfected it and made it quite a robust engine I’m told. > \*\* Here’s an aviation geek checking in: I don’t think there has ever been a radial engine with four banks. I could be wrong, but _damn_, that’d be ugly. I think, too, that B-29’s had Wright engines and Corsairs had P&W, as did a number of other fighter types. I can’t remember the model number 'cause there were a fair number of eighteen cylinder two-bank radials during the war. Why the Corsair had such a long nose is up for debate. ---
**Author:** ![Boo\_Boo\_Foo](https://avatars.discourse-cdn.com/v4/letter/b/e274bd/32.png) [@Boo\_Boo\_Foo](https://boards.straightdope.com/u/Boo_Boo_Foo)\ **Post date:** [September 2, 2003, 8:06am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/8 "2003-09-02T08:06:33Z")
Here ya go… The Pratt and Whitney R-4360 “Wasp Major” [http://www.wpafb.af.mil/museum/engines/eng34a.htm](http://www.wpafb.af.mil/museum/engines/eng34a.htm) This engine featured in the B29 and had magnesium crankshafts believe it or not, to save weight. But they were dreadfully prone to catching on fire, as magnesium does. I’m not quite sure that this engine featured in the Corsair. I suspect it was just the “Twin Wasp” which featured two banks of 7 cylinders. ---
**Author:** ![Doc\_Nickel](https://avatars.discourse-cdn.com/v4/letter/d/5fc32e/32.png) [@Doc\_Nickel](https://boards.straightdope.com/u/Doc_Nickel)\ **Post date:** [September 2, 2003, 9:53am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/9 "2003-09-02T09:53:06Z")
I seem to recall the _Constellation_ had a four-bank radial. I drove past a shop that had three of the engines sitting there most of last summer. I’m guessing, four banks of nine, was it? I may even be able to get pictures, if I can find out where they got moved to. ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [September 2, 2003, 10:01am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/10 "2003-09-02T10:01:06Z")
You need to google “f2g”. Then you get things like [this](http://www.acepilots.com/planes/f4u_corsair.html): > [@](#): > > Perhaps I missed it on the Corsair page - the most powerful Corsair ever built, the Goodyear built F2G with the Pratt & Whitney **R-4360 corncob 28 cylinder engine (four rows of seven cylinders**), contrasting with the **P & W R-2800 18 cylinder engine in the normal Corsair**. Fifteen of these were built, five being the F2G-1 beginning with bureau number 88454. These five were land lubbers, although the wings could be folded manually. The remaining 10 were fully carrierized and were F2G-2’s. (bolding mine) ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [September 2, 2003, 10:04am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/11 "2003-09-02T10:04:15Z")
And a nice picture of a Corsair F2G with the four bank engine can be seen here: [http://www.museumofflight.org/collections/craftimagedisplay.html?ID=124&ImageNumber=1](http://www.museumofflight.org/collections/craftimagedisplay.html?ID=124&ImageNumber=1) ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [September 2, 2003, 11:19am UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/12 "2003-09-02T11:19:11Z")
Back to the OP: while the USAAC tested the YA-10 with a radial for its survivability, it was designed as a ground attack aircraft. The radial fighters of the U.S. in WWII were not actually intended _initially_ as ground support craft. (The P-47, for example, was designed as a high altitude fighter that actually outperformed its sexier rival, the P-51 above 40,000 feet, but since there weren’t any air battles being fought at 40,000+ feet in WWII, it wound up being used as ground attack.) The most frequent reason given for the use of radials, especially by the U.S. and Japanese navies, was actually weight. The weight-to-horsepower ratio for radials was a good deal better than the for in-lines at the start of WWII and a lighter, more powerful engine was felt to be a better deal than a heavier, more streamlined engine–particularly when bouncing a plane on the deck of a carrier. ---
**Author:** ![herman\_and\_bill](https://avatars.discourse-cdn.com/v4/letter/h/f1d935/32.png) [@herman\_and\_bill](https://boards.straightdope.com/u/herman_and_bill)\ **Post date:** [September 2, 2003, 12:12pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/13 "2003-09-02T12:12:28Z")
Answer to the origina question. Navy regulations specified an air cooled engine, liquid cooled engines were heavier, more vulnerable and harder to maintain. The Corsar had a double bank 18 cylinder air=cooled radial engine ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [September 2, 2003, 12:37pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/14 "2003-09-02T12:37:22Z")
- - - I have a book somewhere that gives two reasons: radial engines can be made lighter than inlines because the crankshaft case is shorter in a radial than in any in-line arrangement, _and_ radial engines also happen to be easy to air-cool (and for aircraft, air-cooling is easier than water cooling). ~ ---
**Author:** ![Beryl\_Mooncalf\_1](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@Beryl\_Mooncalf\_1](https://boards.straightdope.com/u/Beryl_Mooncalf_1)\ **Post date:** [September 2, 2003, 1:17pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/15 "2003-09-02T13:17:12Z")
This cite is almost relevant, but none the less, it is well worth a little of your time. World War II Pilots Association. This is also very well done web page. If you get a few pages deep, there are some interesting stories from the people who were there. [WWIIPilotsAssn](http://www.worldwar2pilots.com/) Hope the hijack is forgivable. (turn on the sound too) ---
**Author:** ![OttoDaFe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ottodafe/32/356_2.png) [@OttoDaFe](https://boards.straightdope.com/u/OttoDaFe)\ **Post date:** [September 2, 2003, 1:37pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/16 "2003-09-02T13:37:21Z")
> [@](#): > > \*Originally posted by Brutus \* > \*\*…And my estimation of the bravery of WW2 pilots just went up yet another notch. Landing on a carrier, tricky enough, but then you couldn’t quite see it, and oh ya, your prop may scrape the deck. God bless 'em… > \*\* Actually, any carrier pilot who concentrated on the deck, rather than the LSO (Landing Signal Officer) ran a very high risk of either hitting the stern of the carrier or plowing into planes parked forward. The LSO was there precisely because the pilot, even if he _could_ see the deck, was in no position to gauge his approach relative to the ship. But your point is well taken. **Boo Boo Foo** , thanks for the SD on the British and the Corsair. I remember reading that a long time ago, but I’d forgotten it. What I had in mind was the tendency of the earlier versions to bounce severely on touchdown, sometimes out of the arresting gear, over the barrier, and into the aforementioned parked planes. One other element of the radial vs inline debate: as many “classic bug” owners can attest, changing a damaged cylinder on an aircooled engine is a (relatively) simple process. But just try it on an Allison or Merlin. . . . ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [September 2, 2003, 1:40pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/17 "2003-09-02T13:40:01Z")
**herman\_and\_bill** ’s answer is probably the only really sensible answer. The USN only had radial engines, because Navy regulations said that they should. Other countries used inlines, the US used inlines in heaps of other aircraft. The USN used the P-39 for carrier work early on, maybe someone decided that it was bad _because_ of the inline engine and so therefore… ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [September 2, 2003, 3:06pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/18 "2003-09-02T15:06:47Z")
> [@](#): > > Other countries used inlines, the US used inlines in heaps of other aircraft. The USN used the P-39 for carrier work early on, maybe someone decided that it was bad because of the inline engine and so therefore… I have never heard of the Navy even _looking_ at Bell’s Aircobra; it was certainly never delivered to the Navy as an operational aircraft. While it is true that the Navy requirements were the determining factor, the Navy was not actually _arbitrary_ in their decisions (even when they were wrong). As noted, above, the reason behind the Navy’s preference for radials was their lighter weight (with corresponding higher horsepower-to-pounds ratio) and their serviceability. (Interestingly, once WWII was over, aside from a few scattered developments like the Twin Mustang, nearly the whole world gave up on in-lines, using radials until they were replaced by turbines.) ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [September 2, 2003, 3:45pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/19 "2003-09-02T15:45:53Z")
> [@](#): > > \*Originally posted by Desmostylus \* > \*\*And a nice picture of a Corsair F2G with the four bank engine can be seen here: > > [http://www.museumofflight.org/collections/craftimagedisplay.html?ID=124&ImageNumber=1](http://www.museumofflight.org/collections/craftimagedisplay.html?ID=124&ImageNumber=1) \*\* The plane in the cite isn’t the Chance-Vought F-4U that was operational in WWII. [That plane](http://www.warbirdalley.com/f4u.htm) had a Pratt and Whitney R2800- two row radial engine. One of the best aircraft engines ever made, I think. Having a radial engine doesn’t mean much as far as forward visibility on the ground is concerned. The P-47 had a radial engine and forward visibility was terrible. For taxiing a crewman would often ride on the wing to direct the pilot who couldn’t see much. That was true of the P-51 also. The only way to improve ground visibility for such planes is tricycle landing gear, the only sensible landing gear arrangement in existence. Incidently this site is one of the few that is honest about aircraft speeds. Most such sites give a top speed figure only, and those are outlandish as far as real performance goes. This site gives the Corsair cruising speed as 185 mph which is an honest number. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [September 2, 2003, 3:57pm UTC](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084/20 "2003-09-02T15:57:50Z")
> [@](#): > > One of the best aircraft engines ever made, I think. You’re just prejudiced. (I think I remember you saying you drove a B-26.) But, yeah, the [Pratt and Whitney R-2800 Double Wasp](http://www.aviation-history.com/engines/pr-2800.htm) powered the P-47, the F4U, the F6F, the B-26 Marauder, the A-26 Invader, and several cargo carriers. [Next page](https://boards.straightdope.com/t/why-did-ww2-era-carrier-aircraft-tend-to-have-radial-engines/199084.md?page=2)