Radials vs Inlines in the PTO?

RacingMustang · **Posted:** Fri May 22, 2015 8:22 am

Howdy...

Simple question: Why did WWII Pacific fighters and fighter-bombers tend to have radial engines whereas the European theater had inlines? There are some crossovers like the FW and Jug in Europe and the Mustang, P-38, and Ki-61 in the Pacific, but in general it appears to be radials in the PTO and inlines in the ETO.

Perhaps this is has been discussed before, but any ideas?

RacingMustang · **Posted:** Fri May 22, 2015 8:25 am

Just thinking out loud here...

Are radials quicker to hit max RPM at low speed for carrier takeoffs? Can inlines not take the stresses of carrier landings?

Scott Rose · **Posted:** Fri May 22, 2015 8:34 am

Best guess. Navy vs Army Air Force. Navy always preferred radials. Probably for durability and/or reliability. The PTO was for the most part a Navy run war, at least for the majority of it. I think that influenced the radial vs. inline more than anything else.

Just my opinion.

JohnB · **Posted:** Fri May 22, 2015 9:15 am

RacingMustang wrote:

Howdy...

Simple question: Why did WWII Pacific fighters and fighter-bombers tend to have radial engines whereas the European theater had inlines?

Let's ask all the PTO P-40 and P-38 pilots

Remember, the Navy standardized on radials in the 30s ...so they don't count in your hypothesis.

Really, P-38s and P-40s had their greatest successes in the Pacific.
And the P-47 had it's greatest results in ETO.
The reason why the P-51 was so common at the end of the war in Europe is the USAAF was standardizing on the type....even in the Pacific (remember all the P-51 squadrons escorting B-29s).

Basically, I disagree with your premise. There is no proof for your thesis.

Scott Rose · **Posted:** Fri May 22, 2015 9:18 am

JohnB wrote:

RacingMustang wrote:

Howdy...

Simple question: Why did WWII Pacific fighters and fighter-bombers tend to have radial engines whereas the European theater had inlines?

Let's ask all the PTO P-40 and P-38 pilots

Remember, the Navy standardized on radials at the end of the 30s...so they don't count in your hypothesis.

Really, P-38s and P-40s had their greatest successes in the Pacific.
And the P-47 had it's greatest results in ETO.
The reason why the P-51 was the standard fighter at the end of the war in Europe is the USAAF was standardizing on the type....even in the pacific (remember all the P-51 squadrons escorting B-29s).

Basically, I disagree with your premise. There is no proof for your thesis.

My opinion was a basic one going purely on the strength of Naval air in the Pacific vs. Europe. There are always exceptions or course. And the standardization by the Navy on radials is relevant, disregard those and there is no argument.

JohnB · **Posted:** Fri May 22, 2015 9:25 am

Scott WRG Editor wrote:

And the standardization by the Navy on radials is relevant, disregard those and there is no argument.

That's what I was trying to say.
Take away the Navy element from the question (since its well known that they were 100% radials) and there is no case for the question.
IIRC, in the late 20s, the Navy was behind the development of the P&W Wasp. So much so that when Boeing wanted one to power its Boeing 40 mailplane, it had to get Navy permission.

Scott Rose · **Posted:** Fri May 22, 2015 9:52 am

JohnB wrote:

Scott WRG Editor wrote:

And the standardization by the Navy on radials is relevant, disregard those and there is no argument.

That's what I was trying to say.
Take away the Navy element from the question (since its well known that they were 100% radials) and there is no case for the question.
IIRC, in the late 20s, the Navy was behind the development of the P&W Wasp. So much so that when Boeing wanted one to power its Boeing 40 mailplane, it had to get Navy permission.

I wonder if thats why the B-17 had radials and not inlines (though I know at least one was fitted with inline engines)

Zachary · **Posted:** Fri May 22, 2015 10:59 am

Just some speculation with no research to back up the idea, but Grumman and United Aircraft Corp. were pretty close to Pratt & Whitney. Just makes sense that they'd use engines manufactured nearby.

RacingMustang · **Posted:** Fri May 22, 2015 11:19 am

JohnB wrote:

RacingMustang wrote:

Howdy...

Simple question: Why did WWII Pacific fighters and fighter-bombers tend to have radial engines whereas the European theater had inlines?

Let's ask all the PTO P-40 and P-38 pilots

Remember, the Navy standardized on radials in the 30s ...so they don't count in your hypothesis.

Really, P-38s and P-40s had their greatest successes in the Pacific.
And the P-47 had it's greatest results in ETO.
The reason why the P-51 was so common at the end of the war in Europe is the USAAF was standardizing on the type....even in the Pacific (remember all the P-51 squadrons escorting B-29s).

Basically, I disagree with your premise. There is no proof for your thesis.

Well there you go...thanks for the education. Didn't realize that the Navy had standardized radials. Cuz you're right: take the Navy planes out and there's little difference ETO/PTO.

Why did the Navy go radial? I guess they were more common and better developed...

maxum96 · **Posted:** Fri May 22, 2015 11:32 am

RacingMustang wrote:

Why did the Navy go radial? I guess they were more common and better developed...

Just a guess here, but simplicity and reliability. No radiator or cooling system to worry about getting damaged in battle. Especially with long over water flights.

Scott Rose · **Posted:** Fri May 22, 2015 11:37 am

maxum96 wrote:

RacingMustang wrote:

Why did the Navy go radial? I guess they were more common and better developed...

Just a guess here, but simplicity and reliability. No radiator or cooling system to worry about getting damaged in battle. Especially with long over water flights.

Thats my take on it. I've read where shot up radials bring the plane home but inline seem a bit more fragile. When you fly over sharks you want to make it home, not just down.

JohnB · **Posted:** Fri May 22, 2015 12:28 pm

Zachary wrote:

Just some speculation with no research to back up the idea, but Grumman and United Aircraft Corp. were pretty close to Pratt & Whitney. Just makes sense that they'd use engines manufactured nearby.

That may have explained why P&Ws were preferred in Grummans, but remember Wright (and others) made radials too.
In fact the pre-war FF and F3F, wartime TBM, and postwar S2F and SA-16s had Wright engines.
The main factor was the Navy reference for radials rather than some business conspiracy.

JohnB · **Posted:** Fri May 22, 2015 12:42 pm

maxum96 wrote:

Just a guess here, but simplicity and reliability.

Not to mention weight...and lower airframe weight means more weapons and/or fuel.

Using the Boeing 40 case again, compared to competing aircraft for air mail contract, thanks to the lighter weight and greater payload offered by the air cooled radial, Boeing's airline could underbid competing firms and still have enough payload capacity to carry passengers. William Boeing said he'd rather carry 200 pounds more mail than water.

Lon Moer · **Posted:** Fri May 22, 2015 2:27 pm

Scott WRG Editor wrote:

maxum96 wrote:

RacingMustang wrote:

Why did the Navy go radial? I guess they were more common and better developed...

Just a guess here, but simplicity and reliability. No radiator or cooling system to worry about getting damaged in battle. Especially with long over water flights.

Thats my take on it. I've read where shot up radials bring the plane home but inline seem a bit more fragile. When you fly over sharks you want to make it home, not just down.

A long long time ago, John Herlihy told me that "radials give 'instant' power on throttle-up, this was very important for carrier operations. The inline's build up power (like a locomotive) and can need a larger area for take-off's"

JFS61 · **Joined:** Mon Apr 30, 2012 12:44 pm **Posts:** 305

maxum96 wrote:

RacingMustang wrote:

Why did the Navy go radial? I guess they were more common and better developed...

Just a guess here, but simplicity and reliability. No radiator or cooling system to worry about getting damaged in battle. Especially with long over water flights.

That, plus it simplifies logistics and frees up valuable space on board ship as you don't need to carry large stocks of coolant around with you as well (not to mention one less volatile substance to be lugging around with you in a combat zone).

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Radials vs Inlines in the PTO?

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