Talk:Airco DH.9A/Archive 1

Archive 1

Internal bomb bay etc

Recent additions to the article claim that the US modifications to the DH.9A that resulted in the USD-9A included removal of the internal bomb compartment, increased fuel capacity and a "Nelson Gun Control System", based on Splendid Vision, Unswerving Purpose: Developing Air Power for the United States Air Force During the First Century of Powered Flight by Diana G Cornelisse. Unfortunately, at least one of these statements is complete nonsence - the DH.9A never had any sort of internal bomb compartment - all bombs were carried on racks under the fuselage or wings. This begs the question as to whether the rest of what Cornelisse says about the USD-9A can be taken at face value - according to Jack Bruce in the 1956 Flight article the USD-9A was extensivley redesigned, with modified wings and tail, a revised fuel system, which appears to have greater capacity and a Browning gun mounted on the Starboard side replacing the Vickers gun on the port side of the British based aircraft. Bombloads were again under the fuselage and wings, but appeared to lighetr than the DH.9A. Production figures also differ - both Bruce and AJ Jackson in De Havilland Aircraft since 1909 state that nine USD-9As were built, five by Engineering Division and another four by Dayton-Wright.Nigel Ish (talk) 18:38, 27 August 2011 (UTC)

Note - I have protected the article to encourage discussion rather than an edit war. MilborneOne (talk) 07:32, 28 August 2011 (UTC)

No mention of an internal compartment in Flights 1956 two parter [1], [2] though Part II goes into some detail of the construction of the USD-9A down to timber and thickness used. (perhaps when the article is unprotected the Flight article should be added to the refs or futher reading) GraemeLeggett (talk) 09:15, 28 August 2011 (UTC)

Both parts of the Flight 1956 J M Bruce article are already used as references in the article. There is also no mention of an internal compartment in the three part Aeroplane Monthly article (June to August 1992) by Philip Jarrett and Owen Thetford).Nigel Ish (talk) 09:33, 28 August 2011 (UTC)

What does the Splendid Vision reference source actually say? By the way, the book should be cited as Helen Kavanaugh-Jones, editor. The mention of Diana G. Cornelisse may be from an article inside the book. FWiW Bzuk (talk) 14:26, 28 August 2011 (UTC).

The books says the same thing I added to the article, that the modification included the removal of an "internal bomb compartment" to make room for additional fuel, as well as modifications to the fuel system, and the addition of the Nelson Gun Control System, which was depicted in a photograph. As a side note, the photos in the book show the DH-9s having no armament. There is no sign of the Browning machine guns Jack Bruce claims replaced the Vickers guns. Photos don't lie, and I would seriously question anything else mentioned in Jack Bruce's "Flight" article. The book also clearly states that only four were manufactured by Dayton-Wright, and used at McCook Field. Bzuk, the book was written by the members of the Air Force History section, under the supervision of AF historian Diana G. Cornelisse. Helen Kavanaugh-Jones was the Chief Editor of the Dayton Journal newspaper, and contributed only the book's introduction. On a matter such as this, if we weight the knowledge of the entire U.S. Air Force's history section against the accuracy of a 1956 magazine article by Jack Bruce it should be pretty clear who's got it right. - Ken keisel (talk) 19:34, 28 August 2011 (UTC)

No truth, only verifiability? Bruce seems to be on top of many of the finer details of the DH-9a and its variants. GraemeLeggett (talk) 21:04, 28 August 2011 (UTC)

So you are saying that Jack Bruce, who was probaly the foremost British expert in British aviation in the First World War and ended up in an extremly senior role at the RAF museum, Andrew Jackson, author of the Putnam book De Havilland Aircraft since 1909 and will have had full access to de Havilland and Westand archives, plus all the people who have seen the DH.9A at the RAF museum at Hendon, which DOES NOT have an internal bomb bay are all not to be trusted? Are you sure this book of yours is talking about the actual British designed DH.9A and not some US built intermediary (perhaps the USD.9, which some sources seem to suggest was also a modified DH.9A)?Nigel Ish (talk) 21:15, 28 August 2011 (UTC)

I think I've found the source of the problem here. Apparently Jack Bruce failed to realize that the DH.9A was developed into two completely different aircraft by the staff at McCook Field, and he has described both aircraft in his article indescriminately. One U.S. version was the USD-9, which was a light bomber. The Air Force does not say that the DH.9A had a bomb bay, and that has never been stated here. Their book does state very clearly that the USD-9 was created from the DH.9A "by ommiting the bomb-carrying compartment in the fuselage, increasing the fuel capacity, adding a Loomis cooling system, a McCook gasoline system, and a Nelson gun control system." Four of this variant were built at McCook Field. The photo of the USD-9 does not show a Browning machine gun on the right side. The other variant was the USD-9A, a reconnissance aircraft. The Air Force states that this variant was developed by modifying the wings and wignspan, adding two paralle flexible .30-caliber Lewis guns to the rim of the rear cockpit, and a single fixed .30-caliber Browning on the right side that fired through the propeller's arc. The Browning had two sights - a ring on the gun, and an Aldis sight on the left side of the pilot's windshield. A control mounted directly to the "camshaft driving member" of the Liberty engine timed the gun's firing through the propeller. A source at McCook Field described the U.S.-designed system as not the "ultimate synchronizer", but it was reliable and adaptable to all aircraft. The USD-9A had a weight of 4,520 lbs. At least four USD-9A were built at McCook Field, including the one converted with a pressurized cockpit. If you add the four USD-9 and at least four USD-9A constructed at McCook you can easily come up with the nine aircraft Bruce claims. Apart from not mentioning an internal bomb storage compartment Bruce is essentially correct on the DH.9A, but he apparently got very confused about the USD-9/USD-9A variants, or didn't even know there was a difference, which has led to this confusion. Mixing up a bomber and a reconissance plane makes it pretty clear that he can't be cited as a reference when describing the U.S. versions. - Ken keisel (talk) 14:55, 29 August 2011 (UTC)

Also, since there seems to be some confusion on spelling, the following is taken from the Merriam-Webster Dictionary:

• pres·sur·ize verb /ˈpreSHəˌrīz/ 
  • pressurised, past participle; pressurised, past tense; pressurises, 3rd person singular present; pressurising, present participle; pressurized, past participle; pressurized, past tense; pressurizes, 3rd person singular present; pressurizing, present participle

• 1.Produce or maintain raised pressure artificially in (a gas or its container)
  • - the mixture was pressurized to 1,900 atmospheres

- a pressurized can

• 2.Maintain a tolerable atmospheric pressure in (an aircraft cabin) at a high altitude
  • - a pressurized cabin

• 3.Attempt to persuade or coerce (someone) into doing something
  • - the protests were an attempt to pressurize the government into bringing an end to the violence
  • - people had been pressurized to vote

• • • In the United States the spelling "pressurized" is generally applied.

Again - the major point is that, despite what the Air Force book says, the DH.9A did not have an internal bomb bay (there isn't room for one) - there are enough detailed descriptions of the DH9A to make that crystal clear, so when they are referring to the "bomb-carrying compartment in the fuselage" they are either not refering to the DH.9A or not referring to a bomb-bay - there were bomb-racks under the fuselage, and were bomb-sight and camera apertures in bay-eight of the fuselage (the front part of the observers compartment) and another camera aperture in bay 10, aft of the observer's cockpit. It is possible that some of this equipment may have been ommitted, either from the USD.9 or USD.9A, and that the precise details have lost or mangled over the years, or that there is some other intermediate variant that did incorporate some sort of internal bomb-bay. The rest of Bruce's description of the USD.9A (Bruce does not talk about the USD.9) is basically the same as yours (i.e Browning gun with 750 rounds mounted on starboard side of fuselage, dual mounted Lewis guns on a Scarff ring at the observer's cockpit), a revised fuel system (134 US Gall main tank and 9 US gallon gravity tank), different wings and (probably) tail surface, and on at least one example, a different shaped rudder.

A J Jackson in De Havilland Aircraft since 1909 states that two Airco built DH.9As were shipped to America , where orders were placed for 4,000 aircraft. Four prototypes were built, two by Dayton-Wright and two by the Engineering Division in August 1918. In October, Dayton-Wright are stated to have delivered four USD-9As (described as having the pilots Browning on the starboard side and a modified rudder, with five more delivered by Engineering Division in November. One was modified to USD-9B standard, with 435 hp Liberty 12A and increased area wings in February 1919, and another (serial number AS.40118) was fitted with the pressurised cabin. Jackson gives three known serial numbers for USD-9s (AS.40026, AS 40042 and AS.40043) and the following serial numbers for USD-9As (AS.40044, 40060, 40061, 40062, 40063, 40067, 40068, 40118 and 40119). Joe Baugher has some of the serial numbers Jackson assigned to USD-9As worn by USD-9sNigel Ish (talk) 15:47, 29 August 2011 (UTC)

From the reading of all the back-and-forth, apparently the confusion may be over whether there was an actual bomb bay which connotes a separate, dedicated section, typically with specialized equipment, such as a release and doors. It appears that what is being described is a compartment or area where bombs could be carried. Did I get this right? FWiW Bzuk (talk) 15:57, 29 August 2011 (UTC).

You got it. Once again, the Air Force states they deleted a "bomb-carrying compartment in the fuselage" in order to add additional fuel. I suspect that this was located behind the rear cockpit, as there is additional fuel storage shown in that location in a cut-away image. This was still an era of throwing small bombs from airplanes by hand, and I wouldn't be surprised if they're referring to an internal storage location for 5 lb bombs. There really shouldn't be much of an issue with the accuracy of the Air Force's information, as it was taken directly from McCook Field records, which are excellent. We seem to be agonizing over the accuracy of comparing the Air Force's records with an article in Flight magazine that was written over 50 years ago, that clearly wasn't accurate in its description of the U.S. variants. - Ken keisel (talk) 16:56, 29 August 2011 (UTC)

The July 1992 issue of Aeroplane Monthly by Philip Jarret has a cutaway that does show a small storage compartment behind the observer's compartment fitted with a sliding door - which would not have been used to carry bombs (maps possibly, but not bombs)- it would have been very awkward for the observer (who would be standing in the scarff ring) to retreive a bomb from there and drop it over the side - accounts indicate that it was hard enough to change the drums on the Lewis gun (or guns), which were held in proper clips). In addition, the Nine-ack was an aircraft of 1918 - and bomber operations had gone well beyond lobbing bombs casually over the side. Bombing was from heights of up to 17000 ft where such tactics would be pointless, while accounts of RAF operations make no mention of the observer manually dropping light bombs.

While it does seem possible (or even probable) that this is the compartment that McCook removed, without clearer accounts it would be original research to say so., while if it is, removal of this compartment by itself is a pretty trivial modification - far less important that the revised cooling system (which is what the snippets of comtemporary reports that can be gleaned from Google Books seem to be going on about) or the different fuel system, or even the revised synchronising gear (assuming that this was a standard fitting and not just something tested at McCook on the USD-9A).Nigel Ish (talk) 20:48, 31 August 2011 (UTC)

I had a look at my books for this, the best one is probably Jane's 'Fighting Aircraft of World War I', it's a modern reprint of a 1919 volume (so I tend to trust it). It describes the DH.9 as a 'DH.4 modified for bombing work' and that the pilot's cockpit was moved aft 'leaving space for bombs in the fuselage'. Jane's describe the DH.9A as an 'enlarged DH.9' with larger engines and increased wing span 'otherwise there is little alteration' (but doesn't say it had internal bomb storage). No mention of US use or conversions. Walk round photos of the RAF Museum DH.9A show a rectangular cut-out and a circular cut-out in the fuselage aft of the undercarriage (but it is restored). This would be the logical place for any internal bomb storage (on the centre of gravity, not under the rear cockpit a la Tiger Moth!). If small bombs were stacked vertically, as in the Heinkel 111, then it's not far fetched at all. The bottom line is that I can't cite the fact that the DH.9A had an internal bomb rack using Jane's as it does not say so. Nimbus (Cumulus nimbus floats by) 23:43, 31 August 2011 (UTC)

Sorry, but I have a copy of that Janes reprint too, and while a fascinating read, with some totally unique and wonderful photos and plans it is pretty totally useless as a reliable source, especially of technical data. A number of reasons why this is so - which I will detail here (more for the fun of it that to have a go at you - than which nothing could be further from my thoughts - 'onest injun).

1. The editor of Janes at the time was one Charles C. Grey. The story of this man's vicious, obsessive, and essentially ideologically driven vendetta against what eventually became the Royal Aircraft Establishment forms a kind of litany through Paul R. Hare's book The Royal Aircraft Factory. Unlike me, Hare refrains from intemperate POV comment - just pointing out at all too frequent intervals what Grey thought of this or that development. For the record, Grey (from its earliest days the editor of the jounal The Aeroplane) was hyterically opposed to any (British) government involement in any aspect of aviation - this was NOT, as I long imagined, directly connected with Billing's largely justified criticism of the RFC's continued use of obsolete B.E.2 aircraft in 1916/17 - but went back to the very beginning (1909) - when the "Factory" was concerned entirely with balloons! As well as his obsession with the existence of the RAE as the source of all Britain's aviation ills Grey had a number of other blind spots ("which to enumerate would lead to prolixity") - just one of which was his notion that the low-winged monoplane was fundamentally "unbalanced" and would necessarily be dangerously unstable, if not entirely uncontrollable (he seems to have suspected photographs of early Brandenburg and Junkers low-winged monoplanes of being "re-touched" to conceal their upper wings). To be fair, low-winged (or low-mid winged) monoplanes were fairly rare in 1919, although they have formed the great majority of fixed wing aircraft built after that date, especially since the early thirties.

2. Even given an unbiased editor with a more up-to-date idea of where aviation was headed in the immediate post-war (WWI of course) years - the war time and immediately post war editions of Janes All the world's aircraft on which our facsimile edition is based suffered from substantial (if patchy) limitations on the information available on various subjects. Most information on particular aircraft type was in fact obtained from the manufacturers (viz. the occasional note to the effect that "nothing has been heard" from an obscure manufacturer since the previous edition) - or from the various flying services. Many of the British aircraft in particular (including the D.H.9A) were in fact still cloaked in wartime secrecy, so that technical details, such as the location of internal bomb bays would have been unavailable or embargoed so far as publication in a popular work like Janes is concerned. For examples of this inaccuracy and incompleteness, by the way, - just read the article on Italian aviation (!) or compare the details of the Christmas Bullet in Janes with the Wiki article!

For what it is worth - the entire bomb load of the D.H.4/D.H.9 family of bombers seems to have been carried on racks under the lower wings. Although the USAF records are prima facie a not unreasonable source (certainly much better than Janes!) in the absence of any contemporary supporting evidence whatsoever one might suspect confusion with the single seat version of the Sopwith 1½ Strutter, some French built examples of which did serve with the USAS in 1917/18, and which DID have a small internal bomb bay, incidentally a very rare if not unique innovation at the time. It is also by no means impossible that a purely American variant of the D.H.4/9 (of which there were many!) may have been fitted with a form of bomb bay which was later removed. This remains complete speculation, however. --Soundofmusicals (talk) 00:50, 1 September 2011 (UTC)

If the DH9A was to have had an internal bomb bay then it would have needed to be somewhere around the aircraft's CofG position, as otherwise releasing the bombs would have resulted in a substantial change of trim. The only place for an internal bomb bay on the 9A was in the fuel tank area over that occupied by the undercarriage vee struts at around the position of the cabane struts - the CofG was at around the one-third chord position back from the leading edge - for wings with stagger roughly half way between corresponding positions on the top and bottom mainplanes. The only other way would have been to extend the fuselage to move the fuel tank and allow the bomb compartment to occupy this position, which would have necessitated a longer fuselage to maintain the CofG at this one-third chord point. Bombs are heavy and occupy a relatively small area, and would have a noticeable effect on the aeroplane's handling otherwise.

BTW, on the issue of credibility and factual accuracy, I would put Flight [3] above almost all other sources, e.g., museums, etc., as if some of the howlers I have seen elsewhere are anything to go by, many can't even get the names of the aircraft right. Most of the articles in Flight are contemporary ones, written by specialised aviation journalists from the period, 1909-to-present, and who know aviation from Avia right through to Zlin, and who know the difference between a Stampe and a Tiger Moth. Their Technical Editor during the 1950s-60s was a certain "W.T.G." - better known as Bill Gunston . — Preceding unsigned comment added by 80.7.147.13 (talk) 17:01, 20 May 2012 (UTC)

USD-9 Numbers

Just an aside:

• 40026 Dayton-Wright USD-9 "P36"
• 40027 to 40033 Cancelled USD-9s
• 40042 Engineering Division USD-9 "P40"
• 40043 Engineering Division USD-9 "P45" (destroyed 1920)
• 40044 Dayton-Wright UDS-9 "P64" also qouted as an "A"

• 40060 Engineering Division UDS-9A "P43"
• 40061 Engineering Division UDS-9A "P47"
• 40062 Engineering Division UDS-9A "P50" (shipped overseas in 1918)
• 40063 Engineering Division USD-9A "P51" (shipped overseas in 1918)
• 40064 Cancelled
• 40065 Cancelled
• 40066 Built ?
• 40067 Engineering Division USD-9A "P71"
• 40068 Engineering Division USD-9A "P74"

• 40118 Dayton-Wright USD-9A "P80" became the pressurised single-seater
• 40119 Dayton-Wright USD-9A "P60" (destroyed 1919)

Some sources say two prototype USD-9s each from Eng Div and D-W (was 40044 converted it has a later McCook Field number which may indicator a later delivery or is it 40066?). Some sources say Dayton-Wright built four and Engineering Division five to give the nine. All a bit murky and sources differ but for what it is worth. MilborneOne (talk) 17:56, 29 August 2011 (UTC)

Even Andrade admits that production records for the U.S.-built DH.4 and DH.9 are spotty. This looks pretty good though. It's certainly in the range of what the references are claiming. - Ken keisel (talk) 18:40, 29 August 2011 (UTC)

Wegg in General Dynamic Aircraft and their Predecessors states production by Dayton Wright (the company is listed under Dayton Wright, although it states that the form Dayton-Wright was also used, particularly postwar) was 3 USD.9As (40044, 40118 and 40119). It does not mention Dayton Wright building USD9s.Nigel Ish (talk) 19:39, 29 August 2011 (UTC)