23
You can see that sort of thing on ultralights that land at 25-30 mph where they may use a solid once-piece wheel made of some elastomeric plastic or rubber. Smaller airplanes however, will use a rubber tire on an aluminum wheel with proper bearings, due to the very high rolling RPM once you are landing above 40 mph (or at least a bushing that can take high ...
19
Out of the box, no. They are worse at handling birdstrikes. But with some thought they can be made much better.
All materials have an elastic range of deformation, and if that is not exceeded, they will assume their original shape without damage. Composites fail if this range is exceeded. First the fibers with the highest elongation fail, which enables the ...
18
The reason for using glassfiber on radome coverings is simple: Electromagnetic transparency. Carbon fiber conducts electricity, so it will absorb much of what the antenna radiates away or "listens" for. Glassfibers are good insulators and transparent to radar waves.
The reason for glassfiber on forward-facing surfaces is impact tolerance. Compared to carbon ...
17
This explanation is given here :
The wing of the 777X is based upon the design of the 787’s wing. It
has less of the sweep of the 787 but 10% more surface area (increased
from 4,702 to 5,562 sq. ft.). The re-shaping has led to a higher
lift-to-drag ratio, which(and) in turn increases usable fuel bulk from
320,863 to 350,410 lb. As a result, the type will ...
16
The single most important thing for an arrestor cable is that it works reliably, compared to this incremental differences in weight or durability are fairly minor considerations.
One of the major advantages of kevlar is that it has a very high strength to weight ratio, however all this really achieves in this context is that the cable is thinner and ...
14
In general, the composite materials are poor compared to metals in impact resistance (in general, composites are not good in resisting compressive loads). This is because the metals and composites respond to impact in different ways.
In case of metals , most of the impact energy is absorbed by the metals through plastic deformation. As the plastic region is ...
13
There's a trade-off between saving weight and improving lift-to-drag ratio.
In the case of the 77X, the efficiency gain of the improved lift-to-drag ratio of the longer wing outweighs the potential weight saving of the shorter wing.
In other words: the drag reduction results in more fuel savings than the weight reduction would.
For long-range aircraft, it ...
9
The short answer is the cables are made from steel because that design has been tested and found suitable for the purpose.
The military, and aviation in general, tends to keep using a working solution once we have one because designing new solutions is expensive and time-consuming.
From a materials science perspective there's no reason you couldn't make an ...
8
Wood and canvas are not meant to be used in humid conditions. All outer surfaces are painted, so they are water repellent and can sustain a shower, but when left to the elements, wooden aircraft deteriorate rapidly. The unprotected structure will take up water and will warp. Wet canvas is less taut, many glues lose strength when wet and plywood will come ...
7
On light aircraft, acrylic windshields have been the norm. On higher speed aircraft, glass and laminates are used, particularly with heated windshields. The laminates may use polyvinyl butyral (PVB) is tough and ductile which enhances mechanical properties and impedes shattering of glass layers and the transmission of cracks from one layer to another.
...
6
In case of composite materals, the usual solution adopted for lightning protection is to have a conductive layer in the structure. Basically, this provides a continuous conductive path of low resistance over the entire aircraft exterior (fuselage, for eg), with additional protection in zones where lightning is most likely to attach (for example, the radome). ...
6
"Carbon fiber filament" for Fused Deposition Modelling (FDM) printers doesn't have the properties you believe it does. While perhaps a little stronger than a plain filament, in comparison to traditional items made of carbon fiber it is actually quite brittle and easily snapped, because the fibers are all chopped up into short pieces and mixed with the ...
6
Short answer: Yes, when used properly. It does have its limits (low melting point, low adhesion with epoxy), but if you design around those limits it helps to raise energy absorption considerably.
Long answer: I've used Spectra for improving the crashworthiness of glider cockpits in a study. That was back in 1987-88 when that stuff was brand new.
I molded ...
5
A little late but I see some points the answers above missed and feel the record needs set straight.
Fixed wing military aircraft typically use thick polycarbonate plies laminated with polyurethane inter layer with various EMI coatings.
Military rotorcraft will use much thinner plies of polycarbonate, acrylic or a combination of both with various EMI ...
5
That is a complicated process. You need:
A positive mold (mandrel) for the canopy.
A negative mold for the canopy frame. For a single prototype you can also use the unfinished fuselage itself.
A fuselage mold with a molded window sill.
First the fuselage positive mold core is built. From that the negative mold is taken, but also a negative mold only for ...
5
Sure. Almost all the modern supersonic combat aircraft incorporate a significant amount of composites in their construction. For example, in case of Dassault rafale:
Composite materials are extensively used in the RAFALE and they account for 70% of the wetted area.
though they account for only 28% of the structural weight. This is in line with other ...
5
The most obvious way is to de-assemble the structure and look inside. This leaves the least amount of doubt.
But there are many ways to do this without destruction.
Ultrasonic: The echo of the ultrasonic ping comes back early (reflection at an inner layer) and in multiple echoes (due to the many boundaries inside the delaminated area). This is easy to do ...
5
There are multiple non-destructive methods to detect delamination in composite materials.
In case the delamination occurs on the surface, it can be easily found by visual inspection. This is the easiest method to detect delaminations; however, this is useful only if the delaminations are visible from the outside (i.e. they are on the surface), which is ...
4
Its a good question. The answer why is part technology, part economics, part life cycle reality and part bureaucracy. In short, it may be possible to build arrester pendants out of other materials than hemp cored steel rope, but life is never that simple.
First off is reliability. For the entire history of CATOBAR aircraft carriers in naval aviation, the ...
4
May be it's better to answer the question the other way around. There are regulations which need to be followed. This also includes bird-strikes. In order to get certified all the requirements have to be accomplished.
The reason new materials are used is because they feature desirable attributes (they are for example lighter or maybe cheaper) while ...
4
No.
Epoxy resin is more specific than the terms polymer or plastic from CFRP. CFRP does also include carbon fibre composites with other duroplastic matrix materials (e.g. phenolic resin) or even thermoplastic matrices.
4
The part looks injection-molded. The choice of transparent, moldable polymers available in the 1950s is manageable. The most likely candidates are:
PVC (back then the most widely used polymer, but normally not used in injection molding)
Celluloid (unlikely due to its high flammability)
PMMA (plexiglass)
Polystyrene
PVC can be detected when a heated copper ...
3
You'd have to find someone with access to the original Airbus failure analysis to know the details, but in general it's more difficult to get good bonds with Kevlar laminates compared to graphite or glass (something to do with helpful reactive compounds on the surface of glass and graphite fibres that Kevlar lacks), and special surface treatments and epoxies ...
3
Components like linkages on a wing flap system can be considered to be the local ambient temperature, subject to some lag if the plane is moving between large temperature changes, because of the time for the components to soak.
So a plane descending from 40000 ft after a cruise at that altitude may have components cold-soaked to ambient, say -40C, and if the ...
2
Many of the "benefits" you listed just don't matter:
It's lighter, more flexible, more durable, can tolerate more temperature extremes, is not susceptible to corrosion, and it might even be cheaper - since it's made from nylon threads. It also has the added advantage of being less dangerous in the rare event of a cable break under load.
Lighter: This is ...
2
I agree with the answer from ymb1, but I think that the underlying rationale would be useful to add as well. I've looked into lightning strike protection a little bit for a small helicopter design project I worked on and am drawing from that and a useful article from Composite World (http://www.compositesworld.com/articles/lightning-strike-protection-...
2
From Boeing's AERO:
Areas that have the greatest likelihood of a direct lightning attachment incorporate some type of lightning protection. Boeing performs testing that ensures the adequacy of lightning protection. Composite parts that are in lightning-strike prone areas must have appropriate lightning protection.
Lightning protection on airplanes ...
2
Give the part to a machinist who works with plastics. He will touch the part to a grinding wheel, melting the plastic and making smoke. By smelling the smoke and looking at how the plastic melts, he will be able to tell you which plastic compound the part is made of.
2
Aircraft fabric would be too heavy for a person carrying homebuilt orni-contraption. What you are looking for is 3M Mylar/Tedlar. It has been used as a covering material for a number of ultralights like the Lazair for many years.
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