FLYBOYJ
"THE GREAT GAZOO"
I would say yes if they were applicable to the production serial numbers.
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I would say yes if they were applicable to the production serial numbers.About the remarks at the bottom of page 3 - did they apply to ALL B-17F/G aircraft or just the F models?
Iron and steels have a big variance in thermal expansion...............
I am sure if i was an issue in USA aviation there would be conventions to cope.
What do you mean, you would say yes?I would say yes if they were applicable to the production serial numbers.
Read the notes - it tells what production serial numbers are applicable to a given part number.What do you mean, you would say yes?
What do you mean, you would say yes?
I was being cynical in my response...
You're getting very confused here with regards to single linear structure items and large aircraft assembly tooling that rival the primary structure of a battleship.
There is no substancial thermal expansion when you're talking about an aircraft assembly jig the size of a house and with dozens of gussets and fillets that allows no movement and in some cases are held to .0000 tolerances (look at the photo I posted in post 42).
Maybe the B-24 didn't expand that much because some considered it ugly!
Thermal expansion affects everything, the biggest problems it caused historically were to makers of clocks/chronometers. At one time there was a prize worth millions in todays money just to produce a time piece that kept accurate time at sea. The expansion of a pendulum or spring is so small it is almost impossible to measure but it affects accuracy, bimetallic strips were used to counter this effect as early as 1730. I have no doubt that what you saw and worked on was done just fine but I am also certain that thermal expansion was considered at the design stage.
I was careful with my posts to mention Iron and steels, steel is just an alloy of Iron but has many different structures, The attached table quotes 4 types however there are many more. It only has one value for aluminium, but aircraft were not always made from aluminium itself but alloys of it.
Coefficients of Linear Thermal Expansion
It is possible that some wings some where didnt fit. My money would be on someone not doing things to procedure rather than there being no procedure to account for temperature differentials. It is basic engineering.
It is difficult to discuss two different topics without some misunderstanding and I think we have had a misunderstanding. The effects of thermal expansion and even some quite complex metallurgy was known to ancient cultures, even if they didnt know why the things they did worked. Discussion of metallurgical effects can be interesting and informative especially to those who have never studied it. My points in this discussion is that:Appreciate the link but this is something I'm fully aware of - spent many years at heat treating facilities. I think your last sentence sums it up. If thermal expansion was an issue in aircraft tooling (especially during WW2) this would have been well documented. The biggest issue I ever heard of with regards to large production tooling was the tooling being moved and not properly leveled.
Agree on all points. I've seen issues on structural components where thermal expansion was deemed the culprit, but I'll remain, you're not going to see this on a huge assembly tool (as shown on post 42)It is difficult to discuss two different topics without some misunderstanding and I think we have had a misunderstanding. The effects of thermal expansion and even some quite complex metallurgy was known to ancient cultures, even if they didnt know why the things they did worked. Discussion of metallurgical effects can be interesting and informative especially to those who have never studied it. My points in this discussion is that:
1 All metals in aircraft experience thermal expansion to some extent.
2 By WW2 thermal expansion was so well known it was built in to engineering custom and practice. In terms of this discussion (as previously stated) it may have been the case that some assemblies did not fit but I cannot believe that thermal expansion was the cause, and lack of knowledge of thermal expansion was certainly not the cause.
Maybe I am just a bit "irked" that great engineers many of whom are not named or living are portrayed as buffoons simply from a story about wings not fitting because they didnt realise a temperature differential was important. It bears as much weight in fact as eating carrots improving night vision.
Joe, every night of the week a girl get pregnant and a drunk crashes a car. That does not invalidate all the research on contraception and drink driving, In some cases people may forget the possibility of the effects of thermal expansion, just like they forget the effects of driving on ice, I cannot believe that ever happened on major assemblies on the USAs front line bomber force.Agree on all points. I've seen issues on structural components where thermal expansion was deemed the culprit, but I'll remain, you're not going to see this on a huge assembly tool (as shown on post 42)
On an assembled piece of structure in post assembly - absolutely, I've actually seen it; On a huge assembly jig - no way! I've probably seen 500 large components built on similar jigs shown in post 42, there was never a peep about thermal expansion on the fixtures by tool and die makers, tooling inspectors or tooling engineers.Joe, every night of the week a girl get pregnant and a drunk crashes a car. That does not invalidate all the research on contraception and drink driving, In some cases people may forget the possibility of the effects of thermal expansion, just like they forget the effects of driving on ice, I cannot believe that ever happened on major assemblies on the USAs front line bomber force.
About the remarks at the bottom of page 3 - did they apply to ALL B-17F/G aircraft or just the F models?
DO wings do not completely fit BO and VE aircraft, etc. The reasons are covered in the big note (*) at the bottom of the page but that also indicates that in a worst case scenario you can fit it to any F model - that is a Boeing wing will fit a Vega with some rework like to the fire system and pressure transmitter system. I am not sure what that would involve but given that the PTM for the B-17 I would expect deleting the cockpit firex controls would be the first priority and given the USAAC/F's love of manuals there was probably even a TO detailing the work required.
Agree - In some respects this is a lot less confusing than some other manuals I've seen. Thanks for breaking this down! I was going to attempt to this this but a little inconvenience called "a job" got in the way!Easy if you are used to deciphering this data but very confusing otherwise.
Who knows? Rumors from former B-17 maintainers. There may have been an issue with this but the cause may have been from something entirely different.What do you suppose may have inspired Freeman's "information" about the reinforced fuselage of Vega-built B-17Fs?
What do you mean, "rumors from former B-17 maintainers"?Who knows? Rumors from former B-17 maintainers. There may have been an issue with this but the cause may have been from something entirely different.
I suspect he meant that Freeman certainly interviewed folks that worked on assembly or field maintenance of B-17's while in service. While they could be considered a primary source the fact is that any author or police detective will tell you is that memory is terrible and very subject to change, hence unreliable.