Talk:Boeing XB-15

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The article states that "due to the technology of the time, a 5,000 mile flight took several days; the crew was made up of several shifts, and bunks allowed them to sleep when off duty". This must be a rewrite of page, where it says that "because a long-range flight, powered by the engines of the time, took several days, the crew had bunks to sleep on between shifts". I think this needs a bit of explanation. My first thought was that the aircraft remained up in the air for day after day, but a quick prod of the calculator shows that, at maximum cruising speed, a 5,000 mile trip would have taken 25 hours. It is my guess therefore that, in this context, Boeing's website is talking about a lengthy combat mission with stop-overs, perhaps in friendly airbases in the Pacific; either that, or we should change "several days" to "several hours". page says that "the crew of ten has soundproofed, heated, and ventilated quarters with rest bunks, a kitchen, and a lavatory", which might make this the first bomber to have a loo. -Ashley Pomeroy 17:31, 26 May 2007 (UTC)

Technology, or mathematics?

The page now says "Due to the technology of the time, a 5,000 mile flight took thirty-three hours at its 152-mph cruising speed"... is that fact really attributable to technology, or just to dividing 5,000 by 152? 81.131.10.150 (talk) 22:15, 23 June 2011 (UTC)

Second largest??

The article says it was the second largest airplane in the world at the time of its completion. I was wondering, what was the first? It might be helpful to mention the first in the article. --208.65.188.23 (talk) 02:52, 23 November 2008 (UTC)

Looks like that distinction belongs to the Tupolev ANT-20 —Preceding unsigned comment added by 76.191.159.88 (talk) 21:02, 10 December 2008 (UTC)

Putnam 71,000 lbs

Tim, what is the book you are referring to when you say the Putnam lists the record weight to be more than 71,000 lbs? Binksternet (talk) 18:03, 2 December 2011 (UTC)

According to Peter M Bowers' Boeing Aircraft since 1916 (Putnam 1989) the record flight involved a weight of 71167 lb to 8200 ft on 30 July 1939 - presumably 14000kg+ is the weight category in which the record was set.Nigel Ish (talk) 18:11, 2 December 2011 (UTC)

Okay, let's list the various flights the XB-15 made regarding cargo weight versus altitude and speed:

Major Caleb Vance Haynes and his copilot William D. Old undertook flight tests at Fairfield, Ohio, lifting very heavy loads in June–August 1939. On June 30 they made two flights lifting cargos of:

• 22,046 pounds (10,000 kg) to 8,228 feet (2,508 m)
• 31,164 pounds (14,136 kg) to 6,561.6 feet (2,000 m)... setting two world records, according to Maurer Maurer (1987) Aviation in the U.S. Army, 1919-1939, pp 359–360. Maurer cites an Air Force pamphlet from 1965 and a 1940 Aircraft Year Book likely reporting the previous year's achievements.
  • In July the National Aeronautics Association (NAA) issued a certificate for an international record for "the greatest payload carried to an altitude of 2,000 metres", per USAF Biography of Caleb Vance Haynes.
• In August the NAA recognized the establishment of an international 5,000 kilometres (3,100 mi) speed record with a 2,000 kilograms (4,400 lb) payload. The latter performance also established a national closed circuit distance record of 3,129.241 miles (5,036.025 km) per USAF Haynes biography and Jack McKillop's webpage.

John C. Fredriksen's The United States Air Force: A Chronology, p 56, appears to conflate the two weight record flights listed by Maurer. Fredriksen puts the 8200-foot altitude and the 15.5-ton (31,000 lbs) weight together on the same flight, July 30, 1939, yielding a single record. His date is a month later. (Fredriksen's book has a typo; it fails to provide units for the figure "15.5" but I think it is obvious from context that tons are intended.)

Ray Merriam follows in Fredriksen's footsteps with his U. S. Warplanes of World War II, p 43, in which he brings the higher weight and the higher altitude together in one record flight. He doesn't list the date and he makes the common mistake of misspelling William D. Old's last name "Olds".

Historian William P. Head doesn't clarify the date but he uses the the same exact figures as Maurer in his book Every inch a soldier: Augustine Warner Robins and the building of U.S. airpower, p 216. Maurer seems more reliable to me and I think we should use his date and figures.

So... the Boeing figure of 71,167 pounds (32,281 kg) looks like a gross aircraft weight achieved while carrying the heavier cargo to the lower altitude on June 30, 1939. Note that the USAF Factsheet says the normal gross weight was 65,068 pounds (29,514 kg) so the aircraft was overloaded by 6,099 pounds (2,766 kg).

Also: the 1943 modifications of the aircraft allowed it to carry even more weight because stronger engines were installed. Merriam says the "allowable gross weight [was] upped to 92,000 pounds." However no record attempts were considered as the much more powerful Boeing B-29 Superfortress had already flown by then. Binksternet (talk) 21:30, 2 December 2011 (UTC)

Bulldozed?

Jack McKillop and Pacific Wrecks both say that the majority of the aircraft was bulldozed eastward off the tarmac and into the Curundu swamp within which Allbrook Field was built. Frank Hohmann said he saw it barely visible in 1980, sinking into the muck.

• http://1000aircraftphotos.com/Contributions/McKillop/5384.htm
• http://www.pacificwrecks.com/aircraft/xb-15/35-277.html

Pacific Wrecks says it was stripped of parts and the tail, so maybe that merits the term "scrapped" which we have in the article at this time. Ray Merriam doesn't hint at the bulldozer finale but he gives the time frame as being "ordered dismantled in June of 1945". For what it's worth. Binksternet (talk) 21:30, 2 December 2011 (UTC)

Engines

The design was to use V-1710's originally, but they weren't available... the V-3420's were NOT to be used — Preceding unsigned comment added by 69.127.44.254 (talk • contribs) 18:49, January 2, 2013

I see some confusion in the various book sources we have. For instance, Jon Lake in The Great Book of Bombers says four Allison V-1710s were intended. Michael John Hardy in Boeing writes the following in 1982: "Boeing's design and mock-up were based on the use of four 1,000 hp Allison V-3420 in-line engines, but these were not available in time and the XB-15 first flew on October 15 1937 with 1,000 hp Twin Wasp R-1380-11 radials." Hardy names the 3420 but he specifies the horsepower of a 1710, which is very confusing. He also overstates the 850 hp of the Twins. The book The Army and Its Air Corps: Army Policy toward Aviation, 1919-1941 agrees with you that four V-1710s were specified but Twin Wasps were substituted. Timothy Moy says in War Machines that the initial engines were "experimental liquid-cooled twelve-hundred-horsepower Allison engines" without naming the model. Binksternet (talk) 19:26, 2 January 2013 (UTC)

Peter M. Bowers in Boeing Aircraft since 1916 also states V-3420s, although he doesn't specify a power.Nigel Ish (talk) 19:31, 2 January 2013 (UTC)

Payload record

I assume that this 31,000+lbs lifted was achieved largely by leaving the fuel tanks mostly empty, because if the normal payload is a maximum of 8,000lbs + fuel, it would seem that you'd have to loose some weight quickly in order not to exceed the maximum takeoff weight. With full fuel, you'd be 20,000lbs or so overweight on takeoff carrying 31,000lbs. Or does the fuel COUNT as part of a "payload"? I mean, what is the difference taking off with an 8,000lb bombload and full fuel at maximum weight, and taking off with a gigantic payload and little fuel, equalling the same maximum weight. I mean, you can't exceed the maximum takeoff limits to any appreciable degree, can you? That would also mean that, if it couldn't climb over 8,200ft at it's maximum weight, then combat takeoffs at maximum weight (fuel + weapons) would be forced to takeoff and fly under 8,000ft, and slowly climb as the fuel burned off and the weight dropped. Which brings me to wonder, is the 71,000lb maximum weight quoted based on this "superheavy" takeoff configuration, or is that a maximum weight expected to be reached in combat operations, with full weapons and fuel load? It would be nice to differentiate between the two. And if they are different, what is a a typical "combat takeoff weight", as opposed to maximum? Many aircraft articles list both..45Colt 08:03, 17 August 2015 (UTC)

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