Assembly details for LR aircrafts 1

[luca28]

Hi all, I'm Luca from Italy, almost graduated in aeronautical engineering at Rome University.
Italian didactics are most of all theoretical, people never get in touch with real stuff, laboratories demonstrations and tests are very few.
Things get worse regarding structural subject, the one I've got my specialization in. I.e., the only details that we've got of wing section are the ones from Bruhn and Megson bibles.
This is the reasons why I've decided to join this forum, no chance to get something like this in Italy.
I just have a couple of questions as far as wings and fuselage assemblies of longe range liners are concerned.
I understand that this forum is not for students, anyway I hope nobody might flag my posts.
Thks.

 

[MikeHalloran]

So, ask a question already.

Omit the biography.


Mike Halloran
Pembroke Pines, FL, USA

 

[luca28]

1) wing type of liners: is it multispar or beam box ?

2) skin to spar join: regarding attached dwg, is the skin usually riveted on spar flange? if such, is top surface of spar flange machined in order to match the curved profile of the skin, or is skin just mounted on straight flange surface?

3) spar and rib cutouts: as indicated in the picture, profile of cutout isn't flat, but bent. Is this for stiffening purpose of the rib? And how is this bending obtained?

thks.

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http://files.engineering.com/getfil...6-9720-4611-bff9-00974d8e45b2&file=cutout.jpg

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http://files.engineering.com/getfil...-4bf3-9bc5-49d270e629d2&file=spar_flanges.jpg

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[rb1957]

1) box beam

2) machined to profile

3) flanged lightening hole ... flange can be formed or machined

Michael Niu's book, and of course Bruhn, and Flight's archive of cut-aways would be a good reference source for this type of info.

 

[KENAT]

Internet search should turn up some cut-aways.

As part of my Aero degree we actually had to visit an aviation museum to see real aircraft, and I made a couple of trips to military installations with some of the organizations at university in part to do similar.

So - are there any museums or similar near you? Is the italian air force museum within visiting distance?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[luca28]

thks rb1957.

2) what happens instead for small aircrafts, like Seneca or Cessna? Is spar flange still machined?

3) why is flange needed for cutout? to resist buckling ?

Unfortunately there's nothing on Bruhn, neither Megson. I'll try Niu on Amazon, I've been told it's an excellent text, with practical information.

@ KENAT: I've been several times to italian a.c. museum, but no liners inside ;-)

 

[rb1957]

2) yes ... only the most simple planes would use flat (ie 90deg) spar flanges. some small projects invest in extrusions to align the spar flanges to the wing profile.

3) yes, the flange stablizes the web in shear

i'm guessing you don't know the title of bruhn "analysis of flight vehicle structures" ... i got many hits for "bruhn flight structures". make sure to visit "flightglobal.com" the home of Flight International magazine.

 

[luca28]

Bruhn's ANALYSIS OF FLIGHT VEHICLE STRUCTURES is one of the books I've used (together with Megson) for aircrat structure exams, with the exception of last chapters.
And infact I found the detail of 45° cutout flange on para. D3.6, I read it too late ........

Regarding machining of top surface of spar flange, no mention anyway. Just examples of spar caps for distributed loads wing type, as in attached page.

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http://files.engineering.com/getfil...4a6b-a2eb-9c0619517dce&file=wing_sections.jpg

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My question was referred only to concentrated loads wing type, where the flange section is bigger. Anyway I guess answer is the same.
Would be interesting to know how they get such profile: directly by extrusion with die modification? Or with special grinding?

Last question: how is wing washout obtained during fabrication? I guess ribs are stamped with different airfoil profiles.

By the way, FlightGlobal is on my bookmarks, hope to find something there.

Bye and thks a lot for your info

 

[rb1957]

air transport spars are generally machined on a fully atriculated machine tool, if you have to chance to see a large OEM (Alenia ?) it is amazing to watch, or just to see the final piece.

an older way to fabricate the spars was to use "caps and webs" ... machine cap angles (to the profile required) and rivet to a sheet metal web.

i mentioned an extruded spar ... this is for a very simple wing design, without taper so it has a constant section, but it is a custom die (to orient the spar flanges as needed for the wing profile.

wash-out (and other effects) would be built into the wingbox by tooling. 3D drafting programs tell desingers/maunfacturing exactly the shape and orientation needed at each rib station.

 

[luca28]

ok, now is clear

thks again