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Lightening holes standard 1
- Thread starter Zim64
- Start date
SWComposites
Aerospace
Is this for ribs / spars?
What do you mean by "standard"? How to calculate web bucking with flanged holes?
Have you looked at ESDU documents? esdu.com
Also try here: Also look at Niu's Airframe Structural Design and Airframe Stress Analysis books
What do you mean by "standard"? How to calculate web bucking with flanged holes?
Have you looked at ESDU documents? esdu.com
Also try here: Also look at Niu's Airframe Structural Design and Airframe Stress Analysis books
First thing I want to say is "thank you for spelling lightening holes correctly".
Most lightening holes are defined by OEM's in order for the standard design to match the standard tools they actually use. If derived from an older or more universal standard, I haven't seen it.
A common starting point for designing webs with flanged holes is Bruhn, of course. There are some dimensions given for the flanging of the holes. That could mean that an agency such as NACA did some work on this. You might find a trail of clues in chapter C10 and the references at the end.
(Yes, I couldn't help myself and checked: it came from several NACA reports.)
Most lightening holes are defined by OEM's in order for the standard design to match the standard tools they actually use. If derived from an older or more universal standard, I haven't seen it.
A common starting point for designing webs with flanged holes is Bruhn, of course. There are some dimensions given for the flanging of the holes. That could mean that an agency such as NACA did some work on this. You might find a trail of clues in chapter C10 and the references at the end.
(Yes, I couldn't help myself and checked: it came from several NACA reports.)
what tools are around where you're building this ? Where are you, that doesn't have their own standard for lightening holes ? lightening holes are made with dies ... so what dies do you have ?
"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
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1
- #5
RB... Do You remember this thread from many moons ago?...
Hand Calculation of Frame Webs with Flanged Hole
There was an embedded link-to...
NATIONAL, ADVISORY COMMITTEE FOR AERONAUTYCS
ADVANCE RESTRICTED REPORT
THE STRENGTH AND STIFFNESS OF SHEAR WEBS
WITH AND WITHOUT LIGHTENING HOLES
By Paul Kuhn
Also Found this...
naca-wr-l-524 Tests of Beams having Webs with Large Circular Lightening Holes.pdf
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov
Hand Calculation of Frame Webs with Flanged Hole
There was an embedded link-to...
NATIONAL, ADVISORY COMMITTEE FOR AERONAUTYCS
ADVANCE RESTRICTED REPORT
THE STRENGTH AND STIFFNESS OF SHEAR WEBS
WITH AND WITHOUT LIGHTENING HOLES
By Paul Kuhn
Also Found this...
naca-wr-l-524 Tests of Beams having Webs with Large Circular Lightening Holes.pdf
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov
SWComposites
Aerospace
rb - put them under your pillow each night. 
John Thorp used-to call lightening holes 'weakening holes'... they required significant analysis and testing to ensure that the material removed and the edge stiffening were balanced to ensure that the remaining strength/stiffness of the web was still adequate to carry ultimate loads for the desired life.
For small GA aircraft he was NOT a fan... effort to design/analyze/test lightened [weakened] structure had to be worth the effort. Mass production tooling and high production rates often made the trade-off 'worth-it'... but not onsey-twoseys.
On this subject...
"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." Antoine de Saint Exupéry
"Simplicate and Add Lightness.” --Ed Heinemann
"Simplicity is not a simple thing.” –Charlie Chaplin
"‘Elegant simplicity’ is never ‘simple’ to attain.” –me
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov
For small GA aircraft he was NOT a fan... effort to design/analyze/test lightened [weakened] structure had to be worth the effort. Mass production tooling and high production rates often made the trade-off 'worth-it'... but not onsey-twoseys.
On this subject...
"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." Antoine de Saint Exupéry
"Simplicate and Add Lightness.” --Ed Heinemann
"Simplicity is not a simple thing.” –Charlie Chaplin
"‘Elegant simplicity’ is never ‘simple’ to attain.” –me
Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov
At one place I worked at, "lightening" holes in machined pieces were called "heavying" holes ...
in a sheet metal web, the flange is just some web material so you save the weight of the hole.
In machined pieces it's typical to pad-up around the holes and typically the pad-up added more weight than the hole removed.
"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
in a sheet metal web, the flange is just some web material so you save the weight of the hole.
In machined pieces it's typical to pad-up around the holes and typically the pad-up added more weight than the hole removed.
"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.
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