Author Topic: main spar of the Fw190 (Read 3159 times)

agent 009 · « **Reply #75 on:** February 05, 2006, 08:57:27 PM »

I am grateful Crump. I just can't see the bolts & how they are installed or how many per seam.

Crumpp · « **Reply #76 on:** February 05, 2006, 09:39:19 PM »

Np, your welcome. You got photoshop? download it and enlarge.

Bodhi · « **Reply #77 on:** February 05, 2006, 09:59:05 PM »

See Rule #4

Crumpp · « **Reply #78 on:** February 05, 2006, 10:22:57 PM »

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Read the freaking argument

There is no argument Bodhi.

The alloys were different so it's not really comparible. There are no examples of US aluminium spars being welded but there are some examples of aluminum welds on US aircraft.

That has little to no bearing on axis aircraft.

FYI FW-190 spar is provided with a riveted top and bottom cap to further strengthen it.

All the best,

Crumpp

agent 009 · « **Reply #79 on:** February 06, 2006, 01:16:52 AM »

See Rule #4

Bodhi · « **Reply #80 on:** February 06, 2006, 01:32:35 PM »

See Rule #2, #5

niklas · « **Reply #81 on:** February 06, 2006, 03:10:02 PM »

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Originally posted by MiloMorai

Section 5 is no bolted connection. There was the vertical connection to the fuselage (see little holes upperside), therefore they mounted a stronger spar.
The holes in the wing for the guns weakend the wing, thus the spar was strenghted with extra plates around the hole. The numbers there don´t indicate a bolted connection but probably the extra plates.
Flugwerk fw190 has not the holes for the gun in the wing afaik, so they don´t need the strenghtening.

niklas

agent 009 · « **Reply #82 on:** February 06, 2006, 03:24:50 PM »

See Rule #4

Crumpp · « **Reply #83 on:** February 06, 2006, 05:27:15 PM »

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probably the extra plates.

Those are riveted which is equal to being bolted.

I've tried to make it crystal clear that the spar could not be disassembled and was permanently afixed together without spoiling the details for the Museum.

We are going to be putting out some published material on the FW-190 hopefully soon and I am not really interested in making it "old news" before it hits the market.

All the best,

Crumpp

Angus · « **Reply #84 on:** February 07, 2006, 11:14:07 AM »

So what is the best way to assemble a spar?
Rivets? Bolts? Welds?

I'd put my bucks on welds being the strongest, and bolts being the easiens and most friendly for maintenance. Bolts might still be the unsafest.

Just a thought.

Oh, and if you could make the spar all solid, (1 piece) it would be the strongest of the lot for what it weights..,.

niklas · « **Reply #85 on:** February 07, 2006, 12:22:06 PM »

You better don´t weld such a main spar. The deformation due to thermical stress would be too high. Even minor angle deviations from welding at the inner part would influence a lot the position of the wingtip due to the length. Welding also reduces the stress a lot, really a lot.

niklas

Angus · « **Reply #86 on:** February 07, 2006, 12:35:00 PM »

The welds reduce the flexibility right?
But the attachments can join and be welded on rather a large area.
Well, overlapping and bolted is quite strong also.

Crumpp · « **Reply #87 on:** February 07, 2006, 06:39:59 PM »

Actually brazing is not nearly as destructive and if done properly and offers the similar strength to wielding.

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The strength of brazed joints depends on many factors, like dimensions and clearance, brazing-material and absence of defects in the joint itself. Usually it can exceed application requirements, sometimes even base metal strength.

http://www.welding-advisers.com/Brazing.html

It very much depends on the alloy used to how well it either method works.

http://www.welding-advisers.com/Welding_aluminum.html

Welding aluminum is actually more common in the aerospace industry than one would believe from reading this thread.

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Designers of aerospace structures can use the higher elastic modulus, lower density, and, in some cases, higher strength and fracture toughness of aluminum-lithium alloys to reduce structural weight.

The advantages of aluminum-lithium alloys over conventional aluminum alloys include relatively low densities, high elastic modulus, excellent fatigue and cryogenic strength and toughness properties, and superior fatigue crack growth resistance.

The use of aluminum-lithium alloys does not require changes in manufacturing equipment, design methods, or fabrication techniques. In particular, aluminum-lithium alloys have been found to be readily weldable.

http://www.welding-advisers.com/PRACTICAL_WELDING_LETTER-PracticalWeldingLetterNo21.html

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Welding-aluminum is concerned with aluminum alloys weldability. This is a qualitative assessment of the material suitability to be welded by a certain process in a properly designed structure under given conditions, to present a specified quality level (that is without unacceptable defects), and to perform in service according to given requirements.

Therefore...

...materials like aluminum alloys may show different weldability in different conditions for different processes but may still be satisfactorily welded with particular precautions, generally spelled out in detailed procedures.

Welding-aluminum is easy for certain aluminum alloys, in that it can be done without special precautions by most welding processes under most conditions to provide acceptable and consistent welds. It should be remembered however, that aluminum produces easily, just by sitting in air, an impervious layer of aluminum oxide which protects the surface from corrosive attacks, but also interferes with welding. Special cleaning procedures are required to remove the oxide before welding or brazing.

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Welding-aluminum alloys raw materials is performed on Castings, Forgings or Wrought product forms. The properties which make these materials useful for various applications are mostly low density (specific weight), which is about one third that of steel, ease of fabrication, good thermal and electrical conductivity, pleasant appearance, corrosion resistance and also useful relative strength.

Welding-aluminum can be performed on alloys of different properties. The outstanding characteristic of aluminum is its lightness, which is put to profit in transportation, cars, boats, trains, aviation, and moving machine elements. Some of the alloys can be hardened by special procedures of heat treatment, while others can only be strengthened by cold work and deformation.

http://www.welding-advisers.com/Welding-aluminum.html

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Among the disadvantages, the fact that the joint must conform to certain requirements of overlap form, length and clearance, so that butt joints are not recommended, the fact that brazing-alloys are generally more expensive, the use of flux which introduces one more variable, and the need to eliminate its residuals in order to prevent corrosion, the fact (if objectionable) that color of brazing-alloy may be different from that of base metal, some limitations which may arise as to which finishing processes are permitted, and possibly issues of resistance to corrosion, which might be impaired if the brazing joint is less resistant than base material.

Quote

The lower cost 6061 Al attains typical values of 310MPa, which is also superior to, for example, A356 (or 601 type) Al casting alloy whether that alloy is semi-solid cast, squeeze cast or gravity cast. Further fabrication by welding is also available with 6061 aluminium, opening the opportunities for many other applications.

All the best,

Crumpp

rshubert · « **Reply #88 on:** February 08, 2006, 06:15:58 PM »

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Originally posted by Bodhi
flex with bolts is not the issue here. flex in welds was what we were talking about.

For aluminum (and quite a few steels) crack avoidance is best gained by normalizing the finished piece, essentially an annealing process. Welding of any kind puts tremendous stresses in the material, due to the temperature difference between the material at the weld site and the rest of the piece.

I don't know what temperature you would use to normalize a particular aluminum alloy, but it would be between 500 and 900 F.

Bodhi · « **Reply #89 on:** February 09, 2006, 10:12:31 AM »

We do not weld anything that is structural in a spar. Thats why fasteners are used. Hell, about the only thing we ever weld are the original weld joints in specific original fairings joints and such. As for annealing a weld, like an engine mount (Steel), we gas weld the piece allowing it to self anneal in the process.