Doolittle B-25 engine mods?

[RJM]

I've been discussing, well, arguing, with someone about the Doolittle Raids.

With only about 450 feet of carrier deck available, my guess is that they gunned the engines with brakes and chocks on, then pulled away the chocks and tried to launch, into the wind, obviously, with the deck sloping up a wave at the point of departure.

I also assume a compromise between bomb load and takeoff requirements.

The point of contention is the condition of the engines, about which there is no evidence to suggest any modification. I think they would have used the standard R-2600's, but otherwise would have stripped the aircraft of as much as possible.

I think that the raids were quite hastily conceived after Pearl Harbor leaving no time to modify the engines or props perhaps for greater power at takeoff.

The B25 Mitchell was chosen because it was small and powerful.

We are both wondering if Martin Marauders were available, although they couldn't lift as much.

So, standard engines?

[stepwilk]

Slight digression here, but it has always amazed me that one of the early Mitchells to take off--i.e. less deck length to use--successfully got off without takeoff flaps. The pilot readily admitted that he simply forgot them. so there most have been at least some usable margin of performance in those airplanes.

[Kitbag]

This is what Wiki has to say:

Initial planning called for 20 aircraft to fly the mission, and 24 of the group's B-25B Mitchell bombers were diverted to the Mid-Continent Airlines modification center in Minneapolis, Minnesota. Modifications included (but were not restricted to):
Removal of the lower gun turret
Installation of de-icers and anti-icers
Steel blast plates mounted on the fuselage around the upper turret
Removal of the liaison radio set (a weight impediment)
Installation of three additional fuel tanks and support mounts in the bomb bay, crawlway and lower turret area to increase fuel capacity from 646 to 1,141 U.S. gallons (538–950 imp gal; 2,445–4,319 L)
Mock gun barrels installed in the tail cone, and
Replacement of their Norden bombsight with a makeshift aiming sight, devised by pilot Capt. C. Ross Greening and called the "Mark Twain".

ref Craven, Lieutenant Colonel Wesley Frank and Major James Lea Cate, series editors. "Drawing the Battle Line in the Pacific", Army Air Forces in World War II, Vol. I: Plans and Early Operations, January 1939 to August 1942. Chicago: University f Chicago Press, 1948, p439

Two bombers also had cameras mounted to record the results of bombing.

No mention of additional mods to the engines and, as you say time may have been a factor there. I would guess if it was possible they would have been modded.

[RJM]

successfully got off without takeoff flaps. The pilot readily admitted that he simply forgot them.

I read that. Amazing.

Thanks Kitbag. Given the list of other modifications, it seems safe to assume they left the engines alone.

Out of interest, I found this during my investigations in a printed account by Lt. Ted W. Lawson:

"With full flaps, engines at full throttle and his left wing far out over the port side of the Hornet, Doolittle's plane waddled and then lunged slowly into the teeth of the gale that swept down the deck. His left wheel stuck on the white line as if it were a track. His right wing, which had barely cleared the wall of the island as he taxied and was guided up to the starting line, extended nearly to the edge of the starboard side.

We watched him like hawks, wondering what the wind would do to him, and whether we could get off in that little run toward the bow. If he couldn't, we couldn't.

Doolittle picked up more speed and held to his line, and, just as the Hornet lifted itself up on the top of a wave and cut through it at full speed, Doolittle's plane took off. He had yards to spare. He hung his ship almost straight up on its props, until we could see the whole top of his B-25. Then he leveled off and I watched him come around in a tight circle and shoot low over our heads-straight down the line painted on the deck."

[Feathers McGraw]

I remember reading a book about the Doolittle raid when at school, I would estimate that I read it about 32 years ago, but possibly a little longer.

Despite the additional fuel tanks fitted, more extra fuel was carried in 5 gallon cans. After takeoff, as the tank contents decreased, these were emptied into the tank(s) inside the fuselage. The additional range was intended to allow the aircraft to make it further into China as the trip was expected to be very marginal otherwise.

The writer of the book (his name escapes me) clearly indicated his concern over the process as it was impossible to avoid some fuel spillage and hence risk fire or explosion.

[Rotorhead1026]

Some carburetion mods were attempted (to reduce fuel consumption). Unfortunately, the "tweaks" were dialed back while in transit to the west coast (a field mechanic - unaware of the nature of the mission - simply saw that the carbs were out of spec and "fixed" them).

The engines weren't "hopped up" in any way, but the aircraft were lightened considerably.

Originally Posted by RJM

in a printed account by Lt. Ted W. Lawson

Ted was the fellow who took off without flaps. He had them down, but during the power check they were vibrating so badly (30+ knots over the flight deck) that he retracted them. He of course intended to re-extend them for takeoff, but - like you said - he forgot.

[angels one five]

I recall from the book " Thirty Seconds over Tokio " by or about one of the pilots, Ted Lawson, that the Mitchells had to take off prematurely owing to an unexpected encounter with a Japanese merchant ship.
The vessel was quickly disposed of by the Hornet's escorting destroyers but it was feared that the ship might have had time to transmit a report of sighting the US ships.
This early take off, if I remember correctly, resulted in most of the planes failing to reach their intended destination, Chunking. One of them wound up landing on Russian territory and the crew were interned. No doubt the Soviets were delighted to have the opportunity to examine the plane.
Lawson's B-25, nicknamed The Ruptured Duck, crashed in the surf off the Chinese coast when the engines cut while lining up for an emergency landing on a beach.
Ted Lawson suffered leg injuries which resulted in his losing them, and the bomb aimer, named Cleverley, died as a result of his wounds before the crew could reach safety.
It is now a long time since I read "Thirty Seconds over Tokio" but I think I have the above right.

[stepwilk]

"Despite the additional fuel tanks fitted, more extra fuel was carried in 5 gallon cans."

I remember reading--recently--that one of the B-25 pilots saw a five-gallon can go past one of his props at 150 mph, having been emptied and tossed out of an aircraft ahead. If it had hit the prop, of course, he'd have had it.

Also, it wasn't a "merchant ship" that the Hornet encountered but a fishing boat.

And finally, remember that the "450 feet of deck available for takeoff" was available only to the very last B-25 to go. All of the others had increasingly less deck to work with, as they were parked farther forward, and
Doolittle himself--number one in line--had the shortest deck of all.

[Rotorhead1026]

Lawson lost one leg. He left the army after the war but kept flying privately. Cleaver survived his injuries but later lost his life in another crash. The surviving raiders passed through China, where some of the enlisted types were pressed in to service as aircrew. A couple were killed there. David Jones and Ross Greening, among others, were captured in the ETO (Jones was one of the original tunnel captains for "Harry", of Great Escape fame, until the Americans were all transferred to another section of camp).

Is this thread drift , or what?

Originally Posted by angels one five

Ted Lawson suffered leg injuries which resulted in his losing them, and the bomb aimer, named Cleverley, died as a result of his wounds before the crew could reach safety.

[Fareastdriver]

Also, it wasn't a "merchant ship" that the Hornet encountered but a fishing boat

As was the custom then fishing crews used had their families on board on deep sea trips. I remember an American sailor descibing the screams of the children as machine guns tore though their vessel. It was totally unnessary, the boats did not have radio but because of them the B25s were launched far too early which caused all the range problems.
Such is war.

[Rotorhead1026]

??

Actually, it was a picket ship, and it did broadcast a contact report. Since the ships were, IIRC, about 650 miles out, they weren't regarded as an immediate threat - so some element of surprise was retained.

[con-pilot]

As was the custom then fishing crews used had their families on board on deep sea trips. I remember an American sailor descibing the screams of the children as machine guns tore though their vessel. It was totally unnessary, the boats did not have radio but because of them the B25s were launched far too early which caused all the range problems.
Such is war.

I find that extremely hard to believe, as there is a film of the sinking of the vessel involved and it was sunk by heavy gun fire from the escort vessels. No one would have been close enough to hear anything.

Radio or no radio, they group could not take the chance of being discovered and take the chance of losing one of the last two carriers left in the Pacific at the time.

[stepwilk]

"Actually, it was a picket ship..."

As a former merchant seaman, I don't consider anything that small to be a "ship."

[pasir]

...
This is probably of little help - I once asked a retired ships officer about the difference between a ship and a boat - His reply went something along the lines that ' A ship is a vessel that carries boats' - although he said it with a smile.

On the Doolittle raid I think it is recorded that several B25 crew members were captured by the Japs - of which several (3 I beleive) were executed by firing squad - Of others sentenced to life imprisonment 1 died of malnutrition in Jap prison.

...

[Noyade]

remember that the "450 feet of deck available for takeoff" was available only to the very last B-25 to go.

Wouldn't the last guy have about 800 ft ? Or did they park them differently to my imagination below?

[Feathers McGraw]

The Wikipedia page has photographs of at least one takeoff and a picture of the aircraft at the rear of the flight deck, they were offset so that there was some overlap between aircraft front to back, but not a lot.

It says 467 feet available for Doolittle's aircraft to takeoff, so yes this distance would increase as each subsequent takeoff occurred.

[stepwilk]

My misteak and you're right, Noyade. I made the false assumption that the Hornet was 450 feet long. Your drawing is, of course, correct.

How dumb was I? Dumb enough to think an aircraft carrier of that era was 50 feet shorter than the Liberty ships (of that era) that I used to crew aboard.

[pasir]

...

In addition to loss of life and sufferings many of the aircrew were soon to experience - a little known incident prior to the event involved one of the
Hornets ground crew -

The flight deck of a carrier with aircraft on engine run ups can be
a hazardous place under normal conditions - At the time of the take-offs the Hornets deck was heaving in heavy seas and strong winds - It was under these conditions that one of the ground crew slipped and lost an
arm from a B25 prop.

...

[albatross]

In a book I read years ago - might have been Gen Doolittle's autobiography - was it "I'll Never be so Lucky Again"?
He mentioned that mods had been done to the carburetors of the engines to allow maximum range and once the aircraft arrived in California a person returned the Carbs to "Factory settings".
This was only discovered after the ships were at sea and settings could not be returned to the special settings.
My memory is vague as to the details.

[stepwilk]

See Post #6.