Subject: Bomber Series--Douglas B-18 Bolo

From: [email-masked]
Date: 19 Sep 94 17:22:39 GMT

>From [email-masked]

The Douglas B-18 Bolo was a military adaptation of the DC-2 commercial 
transport to the long-range bombing role.  Although totally 
obsolescent by the end of 1941, it was numerically the most important 
long-range bomber in service with the USAAC at the time of America's 
entry into World War 2.  

The origin of the B-18 can be traced back to the same 1934 Army 
competition that led to the famed Boeing B-17.  In May of 1934, the 
Army announced a competition for a multi-engined bomber capable of 
carrying a ton of bombs at more than 200 mph over a distance of 2000 
miles.  This Army requirement envisaged from the start that the 
winning design would have a production run of as many as 220 planes.  
Several manufacturers were invited to submit bids, with the entries to 
be flown at Wright Field in a final competition to select the winner.  

The Douglas entry bore the company designation of DB-1.  It drew 
heavily on the company's experience with its DC-2 commercial airliner.  
The DB-1 was designed around the wings of the DC-2 and was fitted with 
a deeper and fatter fuselage which contained a bomb bay within its 
center section.  The DB-1 had larger tail surfaces than did the 
standard DC-2, plus a wing with a slightly larger span and area 
resulting from the fitting of rounded tips.  A six-man crew was 
carried (two pilots, one navigator/bombardier, plus 3 gunners).  
Defensive armament consisted of three 0.30-cal machine guns, one each 
in manually-operated nose and dorsal turrets, and one firing from a 
ventral hatch.  The dorsal turret was located just ahead of the 
vertical fin and was fully retractable.  It was rather unusual in 
having a rectangular top, so that it lay flush with the upper fuselage 
when retracted.  

The DB-1 made its first flight in April of 1935, powered by a pair of 
850 hp Wright R-1820-G5 air-cooled radials.  It was delivered to 
Wright Field for the competition in August of 1935.  Competitors 
included the Martin 146, which was a streamlined and enlarged version 
of the B-10 twin-engined light bomber then already in Army service, 
plus the four-engined Boeing 299, which was eventually to emerge as 
the famed B-17 Flying Fortress.  Test flights proved the DB-1 to be 
inferior in almost every respect to the Boeing 299.  However, the DB-1 
did have the advantage over the Boeing design in being substantially 
cheaper.  In addition, the crash of the Boeing 299 on October 30, 1935 
caused the USAAC to opt for the conservative approach, and on January 
28, 1936 they ordered 82 B-18s, with the order being increased to 132 
by June.  Fortunately, the Army also ordered 13 Boeing YB-17s.  

Production B-18s were powered by a pair of 930 hp Wright R-1820-45 
radials housed in revised cowlings.  The nose cone was somewhat 
shorter than that of the DB-1 prototype, and it contained more lateral 
windows as well as a bomb-aiming window in its forward lower portion.  

The first production B-18 was delivered to Wright Field on February 
23, 1937.  The DB-1 prototype was brought up to full B-18 standards 
and was redelivered to the Army five days later as serial number 
37-51.  

The DB-2 was a B-18 airframe fitted in March 1937 with a power-driven 
nose turret with an extensively-glazed large bombardier's enclosure.  
It bore the serial number 37-34, which identified it as the last 
aircraft ordered on the original B-18 contract.  However, it was 
delivered out of sequence, and it was actually the 36th B-18 to be 
delivered when it was received at Wright Field on November 8, 1937.  
This modified nose did not prove satisfactory, and the aircraft was 
eventually converted back to standard B-18 configuration before being 
delivered to the 18th Reconnaissance Squadron at Mitchel Field, New 
York.  

The second (and last) major production version of the Douglas bomber 
was the B-18A.  The B-18A differed from the B-18 in having the 
bomb-aimer's position moved upward and forward underneath an extended 
glazed housing, while the flexible forward-firing nose gun was moved 
further back and below and was mounted inside a globular ball turret.  
This led to the rather unusual geometry in which the bombardier sat 
above and ahead of the nose gunner.  A transparent domed cap was added 
to round off the top of the dorsal turret, so that it no longer lay 
flush with the fuselage when retracted.  The B-18A was powered by two 
1000-hp Wright R-1820-53 radials driving fully-feathering propellers.  

177 B-18As were ordered on June 10, 1937, with 78 more being added to 
the contract on June 30, 1938.  The first B-18A was delivered to the 
Army in April of 1938, with the last example being delivered in 
January of 1940.  Only 217 out of the 255 ordered were actually 
delivered as B-18As, the last 38 examples being built as B-23s.  

Fearing the imminent breakout of war in Europe, a delegation from the 
British Air Ministry toured the Douglas plant in late 1938 seeking to 
purchase combat aircraft.  Douglas was unable to interest the British 
in the B-18 design, as it was deemed by the RAF to have insufficient 
power, poor airfield performance, and inadequate defensive armament.  
The RAF chose to order the Lockheed Hudson instead.  However, Douglas 
did succeed in acquiring an order for 20 B-18A from the Royal Canadian 
Air Force (RCAF).  In Canadian service, these 20 planes were 
designated Digby Mk 1.  The Digby was generally similar to the USAAC's 
B-18As, but had 0.303 cal machine guns as well as some other British 
and Canadian equipment.  The first Digby entered RCAF service in late 
1939.  These carried the Canadian serial numbers 738 thru 757.  

In 1939, the DB-1 prototype (which had been delivered to the Army as 
serial number 37-51) was modified to test the feasibility of firing 
large-caliber cannon from aircraft.  A forward-firing 75-mm cannon was 
mounted in a fixed position in the bomb bay and the nose was cut down 
to accommodate the muzzle.  Initial tests were carried out over Lake 
Erie and at the Aberdeen Proving Grounds in Maryland.  Vibration 
during firing proved excessive, and the experiments were eventually 
discontinued.  However, the data gathered was of great value in 
developing the B-25G and H cannon-firing versions of the North 
American Mitchell medium bomber during the war.  

In 1940, 22 B-18s and 17 B-18As had their D-3 and B-7 bomb shackles 
removed so that larger bombs could be carried.  They were redesignated 
B-18M and B-18AM respectively.  

Deliveries of B-18s to Army units began in the first half of 1937, 
with the first examples being test and evaluation aircraft being 
turned over to the Materiel Division at Wright Field, Ohio, the 
Technical Training Command at Chanute Field, Illinois, the Aberdeen 
Proving Ground in Maryland, and Lowry Field in Colorado.  The first 
operation unit to receive the B-18 was the 7th Bombardment Group based 
at Hamilton Field in California.  B-18s later went to the 5th 
Bombardment Group at Luke Field, Oahu, the 19th Bombardment Group and 
38th Reconnaissance Squadron at Mitchel Field, and the 21st 
Reconnaissance Squadron at Langley Field, Virginia.  These units were 
also later supplemented with B-18As, with B-18As also being supplied 
to the 2nd Bombardment Group at Langley Field.  

By the early 1940s, the deficiencies in the B-18/B-18A bomber were 
becoming readily apparent to almost everyone.  In range, in speed, in 
bombload, and particularly in defensive armor and armament, the design 
came up short, and the USAAC conceded that the aircraft was totally 
unsuited in the long-range bombing role for which had originally been 
intended.  To send crews out in such a plane against a well-armed, 
determined foe would have been nothing short of suicidal.  However, in 
spite of the known shortcomings in the B-18/B-18A, the Douglas 
aircraft was the most numerous American bomber type deployed outside 
the Continental United States at the time of Pearl Harbor.  It was 
hoped that the B-18 could play a stopgap role until more suitable 
aircraft became available in quantity.  

In early December of 1941, the 5th and 11th Bombardment Groups at 
Hickam Field, Hawaii had 33 B-18s on strength, whereas the 28th 
Bombardment Squadron at Clark Field in the Philippnes had twelve.  
B-18/B-18As were also stationed with the 6th Bombardment Group in the 
Canal Zone, with the 9th Bombardment Group stationed at airfields in 
Trinidad, St.  Lucia, and Surinam.  When war came to the Pacific, most 
of the B-18/B-18A aircraft based overseas in the Philippines and in 
Hawaii were destroyed on the ground in the initial Japanese onslaught.  
The few Douglas bombers that remained played no significant role in 
subsequent operations.  

The Bolos remaining in the continental USA and in the Carribean were 
then deployed in a defensive role in anticipation of attacks on the US 
mainland.  Fortunately, these attacks never materialized.  In 1942, 
122 B-18As were modified for the maritime reconnaissance bombing role 
to counter the U-boat menace.  These modified aircraft were 
redesignated B-18B.  An SCR-517-T-4 ASV radar set was mounted under a 
radome in the nose, replacing the bomb-aimer's station.  In addition, 
a Mk IV Magnetic Anomaly Detector (MAD) set was installed in a stinger 
tail.  Some B-18Bs were also equipped with a set of retro bombtracks 
underneath the wings which could fire bombs backwards in a prearranged 
pattern.  

B-18Bs are credited with two U-boat kills--U-654 on August 22, 1942 
and U-512 on October 2, 1942.  The antisubmarine role was relatively 
short lived, and the Douglases were superseded in this role in 1943 by 
the B-24 Liberator which had a substantially longer range and a much 
heavier payload.  

Surviving USAAF B-18s ended their useful lives in training and 
transport roles within the continental USA, and saw no further combat 
action.  Two B-18As were modified as unarmed cargo transports under 
the designation C-58.  At the end of the war, those bombers that were 
left were sold as surplus on the commercial market.  Some postwar 
B-18s of various models were operated as cargo or crop-spraying 
aircraft by commercial operators.  The last Canadian Digby was struck 
off strength by the RCAF in 1946.  So ends the career of one of the 
lesser lights of the Second World War.  

The Air Force Museum at Wright-Patterson AFB in Dayton, Ohio has a 
B-18A on display.  It is equipped with a rectangular-topped dorsal 
turret from a B-18.  I am unaware of the serial number or the history 
of this particular plane.  

B-18 serials: 

	36-262/343, 36-431/36-446, and 37-1/34.  

B-18A serials: 

	37-458/634, 38-585/609, and 39-12/64.  
	B-18As 39-27/64 were delivered as B-23s 

Specification of Douglas B-18: 

Two Wright R-1820-45 air cooled radials, rated at 930 hp for takeoff 
and 810 hp at 10,200 feet.  Maximum speed 217 mph at 10,000 feet.  
Cruising speed 167 mph.  Landing speed 64 mph.  Service ceiling 24,200 
feet.  Absolute ceiling 25,850 feet.  Initial climb rate 1355 feet per 
minute.  An altitude of 10,000 feet could be attained in 9.1 minutes.  
Range was 1082 miles with 2200 pounds of bombs and 412 gallons of 
fuel, or 1200 miles with 4400 pounds of bombs and 802 gallons of fuel.  
Maximum ferry range was 2225 miles.  Dimensions: wingspan 89 feet 6 
inches, length 56 feet 8 inches, height 15 feet 2 inches, wing area 
959 square feet.  Weights: 15,719 pounds empty, 21,130 pounds gross, 
27,087 pounds pounds maximum takeoff.  Normal bombload was 2200 
pounds, but a maximum bombload of 4400 pounds could be carried.  Armed 
with three 0.30-inch machine guns in nose, dorsal, and ventral 
positions.  

Specification of Douglas B-18A: 

Two Wright R-1820-53 air cooled radials, rated at 1000 hp for takeoff 
and 850 hp at 9600 feet.  Maximum speed 215.5 mph at 10,000 feet.  
Cruising speed 167 mph.  Landing speed 69 mph.  Service ceiling 23,900 
feet.  Absolute ceiling 25,600 feet.  Initial climb rate 1030 feet per 
minute.  An altitude of 10,000 feet could be attained in 9.9 minutes.  
Range was 1150 miles with 2496 pounds of bombs.  Dimensions: wingspan 
89 feet 6 inches, length 57 feet 10 inches, height 15 feet 2 inches, 
wing area 959 square feet.  Weights: 16,321 pounds empty, 22,123 
pounds gross, 27,673 pounds pounds maximum takeoff.  Normal bombload 
was 2200 pounds, but a maximum bombload of 4400 pounds could be 
carried.  Armed with three 0.30-inch machine guns in nose, dorsal, and 
ventral positions.  

Source: 

  McDonnell Douglas Aircraft Since 1920: Volume 1.  Rene Francillon, 
  Naval Institute Press, 1988.  

  United States Military Aircraft Since 1909, Gordon Swanborough and 
  Peter M. Bowers, Smithsonian, 1989.  

  American Combat Planes, Ray Wagner, Third Edition, Doubleday, 1982.  

Joe Baugher			**************************************
AT&T Bell Laboratories		*  "Round up the usual suspects."    *
1000 E. Warrenville Road	**************************************
P. O. Box 3013
Naperville, Illinois 60566-7013		
(708) 713 4548				
uscbu!jfb                     Who, me?  Speak for AT&T?  Surely you jest!	
[email-masked]