Doolittle B-25 question

b29flteng · **Posted:** Thu Nov 12, 2009 9:28 am

Back in the '60s, I heard a story that the Doolittle B-25s had a carburetion mod done to them. Another story I heard from a different source was that the B-25s used a much higher octane of fuel so as to get a higher horsepower out of the engines for takeoff. Anyone ever hear of this?

Ken · **Posted:** Thu Nov 12, 2009 10:10 am

Books on the raid always refer to the carbs being specially tweeked and the constant fuel-consumption testing done by the Raiders, including their last CONUS flight to board the Hornet.

I have read most of the books out there on the Raid and can't remember anything about special octane fuel. I would assume any final fueling was done aboard ship from the standard supply of avgas already onboard for the Navy aircraft.

I think Ted Lawson's "Thirty Seconds Over Tokyo" specifically talks about mechanics being instructed not to change any carb settings, yet the airplanes were inadvertantly "adjusted" on at least one occasion.

Ski York's airplane which diverted to Vladivostok (due to high fuel consumption) was rumored to have been messed with and/or had new carbs installed prior to departing the Hornet, though I'm not sure which is true.

From an A&P standpoint, I'd be curious to know what was done to the carbs ... and, from a pilot perspective, I'd like to know if the Raiders used any special MP/RPM settings ... and if those were at all similar to those later taught to long-range P-38 pilots by Lindbergh.

The final question would be: How do those techniques affect engine life? Not bad for a military bird when Uncle Sam is paying the repair bills, but how might that affect warbird ops today in a fuel-saving economy?

Garth · **Posted:** Thu Nov 12, 2009 3:54 pm

Ken wrote:

Ski York's airplane which diverted to Vladivostok (due to high fuel consumption) was rumored to have been messed with and/or had new carbs installed prior to departing the Hornet, though I'm not sure which is true.

IIRC one of the B-25s had an engine pulled for repair while on the Hornet. Think it was mentioned in 30 Seconds, but I could be wrong.

b29flteng · **Posted:** Fri Nov 13, 2009 9:31 am

I remember the carbs being readjusted, but could it have been for a much higher octane than 100/130? Then they could have used a higher manifold pressure, thus more horsepower. ???? I heard the story of the special fuel from a guy who worked in an oil refinery.

RyanShort1 · **Posted:** Fri Nov 13, 2009 9:38 am

b29flteng wrote:

I remember the carbs being readjusted, but could it have been for a much higher octane than 100/130? Then they could have used a higher manifold pressure, thus more horsepower. ???? I heard the story of the special fuel from a guy who worked in an oil refinery.

If they used special fuel, that's the first I heard of it.

Ryan

JBoyle · **Posted:** Fri Nov 13, 2009 9:48 am

Jimmy Doolittle did special fuel research for Shell during his hiatus from the military in the 30s...so there could be something to that.
Still the logistics might have prevented that.

I'd guess the B-25s were fueled before being placed on the Hornet?

RyanShort1 · **Posted:** Fri Nov 13, 2009 9:52 am

JBoyle wrote:

Jimmy Doolittle did special fuel research for Shell during his hiatus from the military in the 30s...so there could be something to that.
Still the logistics might have prevented that.

I'd guess the B-25s were fueled before being placed on the Hornet?

I think they were run up several times on the Hornet (there's video of that) and then they were gassed up extra at the last minute with 5 gal. cans. Personally, I think they were using the normal fuel was.

Ryan

gary1954 · **Posted:** Fri Nov 13, 2009 11:28 pm

If we read the same book, IIRC, the Carbs were "tweeked" to optimum performance, and Col. Doolittle told his crews to not let anyone in SD monkey with them. A crew discovered that someone was "adjusting" the carbs prior to loading, and were told to leave them alone. THis is the B-25 mentioned above that had the higher than normal fuel consumption rate. I do not recall EVER reading anything about an engine change on a B-25 at sea and improbable. If they would have had a real need to change an engine, I imagine that the B-25 would have been pushed overboard..

RyanShort1 · **Posted:** Sat Nov 14, 2009 12:39 am

Ok. Here are some answers from Duane Shultz' book The Doolittle Raid.

The B-25s were DRAINED of most of their gasoline before being hoisted by the crane onto the Hornet. So likely they got their fuel for the Raid from the Hornet's own supplies. See page 89.

A number of repairs and precautionary checks were done on board the ship, and apparently at least one aircraft had it's left engine taken out for repair in the ship's workshops. See page 104.

Ryan

gary1954 · **Posted:** Sat Nov 14, 2009 11:49 am

RyanShort1 wrote:

Ok. Here are some answers from Duane Shultz' book The Doolittle Raid.

The B-25s were DRAINED of most of their gasoline before being hoisted by the crane onto the Hornet. So likely they got their fuel for the Raid from the Hornet's own supplies. See page 89.

A number of repairs and precautionary checks were done on board the ship, and apparently at least one aircraft had it's left engine taken out for repair in the ship's workshops. See page 104.

Ryan

Thanks Ryan, I imagine that with those facts as you pointed out wiff reference, that I sit corrected sir. Been known to be wrong before, and I am sure won't be the last time either

.

TonyM · **Posted:** Sun Nov 15, 2009 8:53 am

A very good book on this subject is Carrol V. Glines "The Doolittle Raid", a book that addresses all of the questions in this thread in detail; also see: "The Doolittle Raid 1942, America's First Strike Back at Japan" by Clayton K.S. Chun. And don't forget Doolittle's book "I Could Never Be So Lucky Again." I, too, have read almost every book written on the subject.

As far as my reading goes, there is no mention of special high octane fuel being used on these airplanes here or on the mission. The airplane carbs had been "tweaked" for the mission. Glines: "The carburetors on all the planes had been carefully bench tested and fine tuned to get the maximum mileage while cruising at low atltittude. The engines had to be started carefully with a precise starting procedure."

The 23 Doolittle Raid airplanes were flown to McClellan Field, Sacramento, for a layover prior to being loaded on the USS Hornet (one airplane was damaged on the ground while en route). New propellers were installed on the airplanes at McClellan. Doolittle requested that no ground personnel add or remove any equipment from the airplanes. It was at McClelland that AAF mechanics started re-adjusting the carbs back to spec and operating the engines roughly, causing backfires that threatened to further throw the carbs out of adjustment. Doolittle went ballistic. The 22 airplanes were later flown to Alameda NAS near San Francisco (not San Diego) for loading onto the USS Hornet. After the airplanes landed at Alameda NAS, one by one the airplanes were rolled into a hangar and checked. The first sixteen airplanes that were able to check off were towed to the dock. Fifteen airplanes slated for the mission and one spare airplane were loaded aboard the USS Hornet. All sixteen airplanes were dispatched on the mission. All 23 B-25 crews were loaded aboard the carrier for security reasons.

There are many books that treat the Doolittle Raid and several really good books on the subject.

TonyM.

Warbird Information Exchange

Doolittle B-25 question

Who is online