Boeing stringer extrusion query (B-17)

[Sutts]

Hi,

The longitudinal stiffeners (longeron/stringers) used in the rear fuselage of the B-17 refer to a Boeing specified extrusion and no plan appears to be included for such items.
The 3 key profiles are these:

BAC 1515-504
BAC 1515-506
BAC 1515-507

1. Does anyone know what the -504, -506, -507 represents please? A change in profile or perhaps just a change in material spec?

2. Does anyone know where I can obtain the accurate dimensions for these profiles? I see aerospace suppliers still refer to BAC numbers but few list the ones above - probably a discontinued line.

Thanks!

 

[swampyankee]

You could ask Boeing.

 

[Sutts]

You could ask Boeing.

There is a portal for Boeing customers but it's so tightly wrapped up that I doubt I'd have any luck. I saw a similar request made to someone who had access but he couldn't provide any information due to his non-disclosure agreement!

 

[swampyankee]

There is a portal for Boeing customers but it's so tightly wrapped up that I doubt I'd have any luck. I saw a similar request made to someone who had access but he couldn't provide any information due to his non-disclosure agreement!

Instead of their customer portal, try a letter or phone call to their corporate historian or archivist. They may be more willing to part with data from eighty years ago than something more recent.

 

[MiTasol]

 

[Sutts]

Instead of their customer portal, try a letter or phone call to their corporate historian or archivist. They may be more willing to part with data from eighty years ago than something more recent.

Thanks for the suggestion. Will give it a try.

 

[Sutts]

View attachment 524834
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Thanks for the great information. Can you suggest where I might look to find a reference to the die numbers please? I've been running google searches and using the search facilities of all the extrusion suppliers I can find. I've found a stockist of the -506 which I'll follow up on but no luck on the other 2. Seems to be a spec that isn't used in any modern applications.

Thanks.

 

[EAIAnalog]

The BAC lettering on the front indicates that it is a Boeing Standard drawing. BAC1515 is the standard, and the - numbers point you to which part of the standard. I'm attaching the BAC1515 drawing for your reference. Hope this helps.

 

[Sutts]

The BAC lettering on the front indicates that it is a Boeing Standard drawing. BAC1515 is the standard, and the - numbers point you to which part of the standard. I'm attaching the BAC1515 drawing for your reference. Hope this helps.

Fantastic! Thank you so much, you guys are amazing

 

[dick56]

Hi,

The longitudinal stiffeners (longeron/stringers) used in the rear fuselage of the B-17 refer to a Boeing specified extrusion and no plan appears to be included for such items.
The 3 key profiles are these:

BAC 1515-504
BAC 1515-506
BAC 1515-507

1. Does anyone know what the -504, -506, -507 represents please? A change in profile or perhaps just a change in material spec?

2. Does anyone know where I can obtain the accurate dimensions for these profiles? I see aerospace suppliers still refer to BAC numbers but few list the ones above - probably a discontinued line.

Thanks!

View attachment 524371

 

[dick56]

A few years back I got some info from Boeing Archives at this number 206-865-1780. I don't know if the number is still good.
Dick W

 

[CBBEhr]

Hi,

The longitudinal stiffeners (longeron/stringers) used in the rear fuselage of the B-17 refer to a Boeing specified extrusion and no plan appears to be included for such items.
The 3 key profiles are these:

BAC 1515-504
BAC 1515-506
BAC 1515-507

1. Does anyone know what the -504, -506, -507 represents please? A change in profile or perhaps just a change in material spec?

2. Does anyone know where I can obtain the accurate dimensions for these profiles? I see aerospace suppliers still refer to BAC numbers but few list the ones above - probably a discontinued line.

Thanks!

View attachment 524371

I thought these were roll formed shapes (From memory of out B-17) Evergreen Museum Docent
These are on the B-17 Microfilms available

 

[whstlngdeath]

I believe the dash numbers following the spec are simply variations of the basic shape and/or dimensions. It appears that BAC1515 is still being manufactured by Boeing, but with different dash numbers. Here is a pic of a current version of BAC1515 which cross-references to a generic aerospace extrusion number "TMS60-17044". In the picture, I highlighted the BAC number in red boxes. This is probably pretty close in shape and dimensions to the original -504, -506, -507 extrusions as used in the B-17. It will at least give you an idea of the basic shape and dimensions.

 

[Sutts]

Thanks for all your help guys. Apparently the profiles for these are indeed found on the original microfilm but not all digital sets include them. They can also be found
in the structural repair manual.