A couple more B-17 questions...

[Hoggardhigh]

Hi all,

In my earlier post "Boeing, Douglas & Vega-Built B-17F's", FLYBOYJ said that B-17's built by the so-called "BVD" production pool were structurally identical to one another.

However, while browsing a forum on warbirdinformationexchange.org, I recently stumbled across the following excerpt from Roger Freeman's book "Combat Profile: B-17G Flying Fortress in World War 2":

"Although supplied with design and production plans by Boeing to build the same model as the Seattle Plant, the airframes and equipment differed in several respects. Douglas-built B-17Fs had strengthened mid-wing sections embracing the engine nacelles and these added approximately 450lb to the basic empty weight. Vega also used the same wing section design as Douglas but additionally strengthened part of the fuselage for a total extra weight of approximately 750lb. Apart from giving Vega B-17Fs a different flight attitude, it caused stress concentrations around the radio room where the rear fuselage was bolted to the forward section of the bomb bay. This led to a general preference among combat pilots for Boeing-built aircraft which were reckoned to have slightly better performance and handling qualities."

Where do you suppose the author may have gotten this "information"? Did B-17F/Gs built by all three members of the "BVD" production pool have identical weights, contrary to the above text?

Thanks

 

[swampyankee]

It may be absolutely correct, but it sounds very fishy: both are very significant weight changes, either of which would imply that the aircraft without that strengthening would have structurally-related problems in service, like falling out of the sky without combat damage.

Douglas, Boeing, and Lockheed (which owned Vega) were serious business rivals, it would not be implausible for an employee of any to disparage the others.

 

[Hoggardhigh]

It may be absolutely correct, but it sounds very fishy: both are very significant weight changes, either of which would imply that the aircraft without that strengthening would have structurally-related problems in service, like falling out of the sky without combat damage.

Douglas, Boeing, and Lockheed (which owned Vega) were serious business rivals, it would not be implausible for an employee of any to disparage the others.

Perhaps FLYBOYJ has something to say about it?

 

[FLYBOYJ]

I know Freeman has been dead for a few years but unless he (or someone else) could show a reference for this claim that would indicate this modification was approved by Boeing AND the US government, it's 100% BS. 450-750 empty weight pounds would effect basic "flight manual" performance and the structural differences would call for revised maintenance, repair and parts manuals.

I have an extreme issue with this statement "Although supplied with design and production plans," as anyone who worked on or built aircraft knows you could have all the "plans" in the world, you build aircraft with TOOLING.

I smell shades of Martin Cadin!!!

 

[FLYBOYJ]

Douglas, Boeing, and Lockheed (which owned Vega) were serious business rivals, it would not be implausible for an employee of any to disparage the others.

I met many old time Douglas workers who always claimed they built better planes and had better quality than Lockheed.

 

[Hoggardhigh]

I know Freeman has been dead for a few years but unless he (or someone else) could show a reference for this claim that would indicate this modification was approved by Boeing AND the US government, it's 100% BS. 450-750 empty weight pounds would effect basic "flight manual" performance and the structural differences would call for revised maintenance, repair and parts manuals.

I have an extreme issue with this statement "Although supplied with design and production plans," as anyone who worked on or built aircraft knows you could have all the "plans" in the world, you build aircraft with TOOLING.

I smell shades of Martin Cadin!!!

Does that mean the above quoted text from Freeman's book is inaccurate or most likely so?

 

[swampyankee]

Does that mean the above quoted text from Freeman's book is inaccurate or most likely so?

Freeman may have relied on interviews, which, I think many you will agree, rely on memories that get increasingly unreliable with time.

 

[FLYBOYJ]

Does that mean the above quoted text from Freeman's book is inaccurate or most likely so?

I'll put it in laymen's terms - considering he made those comments without a reference or source, I'd say he's full of sh!t!

 

[Shortround6]

Unless the modifications were known and approved by government inspectors I would also highly doubt such modifications. There were government inspectors monitoring production at many levels of assembly.

There were also penalties attached to delivering over-weight aircraft and while 750lbs might not push an ideal B-17 (one that weighed exactly what the specification called for) over the line to rejection/rework or invoking fines/lower price it sure doesn't leave much wiggle room for production variations.

Unless somebody can come up with actual documentation, like different weight and balance charts for the different aircraft, this sounds like a myth.

 

[FLYBOYJ]

IIRC every US aircraft had to be within a set tolerance (weight, dimensional and performance) of it's design standard, and for some reason 2% rings a bell (I could be wrong and if I am please post the correct number).

 

[Shortround6]

For some reason 3% rings a bell for me but that could well be in error as I have nothing to point to either. I also don't know if the performance spec (where my vague recollection of the 3% comes from) is different than the weight specification.
In any case 3% of 34,000lbs (empty weight of a B-17F?) is 1020lbs and 2% is 680lbs.
I believe, but could be wrong, that there were several levels depending on contract. There was an allowable tolerance under which there was no penalty, There was a higher tolerance under which financial penalties would be imposed, as in so many dollars per pound over weight or per mph under the specified speed (beyond the allowable tolerance) and finally a threshold beyond which the the plane was rejected and had to sent back for rework and retesting before being accepted and thus paid for!

Adding hundreds of pounds to an aircraft without it being accounted for in the contract specifications would be a very risky business decision.

 

[swampyankee]

Freeman may have been repeating anecdote or relying on one or two interviews done decades after the fact. Human memory is notoriously unreliable, which is why competent investigators try to get independent collaboration of eyewitness testimony.

 

[Hoggardhigh]

Of the 500 B-17F's produced by Vega, most of the last 250 examples seem to have remained stateside for training (I suspected this when browsing one of Joe Baugher's serial number pages). Can someone try to explain this?

 

[Hoggardhigh]

Freeman may have been repeating anecdote or relying on one or two interviews done decades after the fact. Human memory is notoriously unreliable, which is why competent investigators try to get independent collaboration of eyewitness testimony.

What do you mean by, "repeating anecdote"?

 

[Shortround6]

Of the 500 B-17F's produced by Vega, most of the last 250 examples seem to have remained stateside for training (I suspected this when browsing one of Joe Baugher's serial number pages). Can someone try to explain this?

A possible explanation might be figured out if someone can find the completion/acceptance dates? As in did Boeing and/or Douglas change over to the G model before Vega did? It would be highly unlikely that all 3 factories changed over in the same week or month. Even the block numbers were not consistent between the factories. An F-40BO was not the same as an F-40VE for example.

 

[Robert Porter]

As far as the strengthened wing spars mentioned on Douglas and Vega built B-17F's I find it often repeated but no citations or references in any of the mentions. I think a logical explanation is that Lockheed led, with Douglas assistance, the development of the prototype that became the XB-38 which was equipped with Allison engines. This aircraft was strengthened in numerous ways during the prototype development and testing. Perhaps that is where this notion started. But entire wings were often replaced in the field due to battle damage or stress fractures and such strengthening would have made that impossible across manufacturers.

 

[Robert Porter]

A possible explanation might be figured out if someone can find the completion/acceptance dates? As in did Boeing and/or Douglas change over to the G model before Vega did? It would be highly unlikely that all 3 factories changed over in the same week or month. Even the block numbers were not consistent between the factories. An F-40BO was not the same as an F-40VE for example.

You are I believe correct, which is why when the BVD group began production of the B-17F's they changed the block numbers to this format.

B-17F-1-BO for Boeing would be equivalent to a B-17F-1-DL and a B-17F-1-VE the added digit just before the manufacturer designator was consistent across manufacturers but if you look at change over dates Boeing would usually increment that number as much as a month ahead of the other two, and their were often delays even between the other two manufacturers incrementing their numbers. Hence a lot of aircraft ended up at post production modification centers to incorporate changes designed but not made in time.

 

[swampyankee]

What do you mean by, "repeating anecdote"?

Anecdotes are undocumented stories. If an author interviews some guy who had worked in the purchasing office at Vega who tells the author the that everybody knew Vega bought rivets from old horseshoes, he's repeating an anecdote. If there is a receipt from Jo's Horseshoe Recycling for 5,000 pounds of horseshoe iron rivets, the interviewee provided corroboration.

Anecdotes usually don't involve bad faith, nor do faulty memories.

 

[Hoggardhigh]

Anecdotes are undocumented stories. If an author interviews some guy who had worked in the purchasing office at Vega who tells the author the that everybody knew Vega bought rivets from old horseshoes, he's repeating an anecdote. If there is a receipt from Jo's Horseshoe Recycling for 5,000 pounds of horseshoe iron rivets, the interviewee provided corroboration.

Anecdotes usually don't involve bad faith, nor do faulty memories.

What are you saying there?

 

[Robert Porter]

A lot of books that have been written over the years relied on interviews where appropriate references and written documentation no longer exists or cannot be found. Since an interview years after the fact is in essence hearsay it is considered anecdotal. Anecdotal is defined as: (of an account) not necessarily true or reliable, because based on personal accounts rather than facts or research. Often these accounts are very well meaning and as truthful as the person being interviewed can make them but they still may be false or incomplete. It is also true that things repeated, true or not, become their own form of truth. So when we collectively encounter an unsupported, by facts or evidence, account, no matter how well intended or how often repeated, care needs to be taken before trusting the account. Most of the time the author had not intentionally injected falsehoods or fabrications into their work. The example we were discussing above, the differences between wing structures on B-17's built by different manufacturers is an excellent example. So far as I can find the account, almost word for word, shows up in 2 books and dozens of web references. Yet I can find no supporting documents or other facts in evidence to support the claim. This appears to be a case of "someone said" with no real supporting information that has gotten repeated over and over until it has taken on a life of its own.