0
$\begingroup$

Can we change the skin and wings of light aircraft from aluminum to foam and fiberglass composite in zenith ch 750 ?

$\endgroup$

closed as too broad by Ralph J, fooot, Sean, xxavier, J. Hougaard Feb 3 at 16:05

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

4
$\begingroup$

Yes. No. A little bit of yes, but overwhelmingly a NO.

It's possible to design and build an aircraft like the CH-750 with fiberglass instead of aluminum, but it's so far above the skill and qualifications of anyone who would ask the question on the web - as opposed to starting by modeling it in ANSYS - that the only realistic answer is "no".

Not because of any intrinsic properties of fiberglass, but simply because of the level of knowledge involved in redesigning an aircraft of this scale, and the fatal consequences of getting it wrong.

$\endgroup$
1
$\begingroup$

I would also check into the weight of the resulting structure. Foam is disappointingly heavy and weak compared with cantilever balsa (and air spaces) construction. Epoxy and fiberglass can be used to reinforce key areas such as wing roots. But stressed skin over a metal framework is a time honored aircraft construction method.

Light carbon composites (technically including wood) are making inroads for future designs as they offer considerable strength that foam does not have and corrosion resistance that metals lack.

Layers of different types of materials are famously used in Mongol bows and show how something like a wing could be built to be both strong and flexible. Plywood is another example.

One thing about aluminum is the thinness of the sheets that fiberglass would have difficulty matching. Weight savings is crucial in aircraft.

$\endgroup$
1
$\begingroup$

Possibly. The right foam, the right resins, the right fiberglass or better fiber such as carbon fiber, layered and cross braced in the right way.

Done wrong, the least of your problems could be a wing that is heavier than the original.

It's not an automatic win, you can't just lay up an aluminum shape in fiberglass and call it a day. It needs to be re-engineered based on all the properties of the new material. Ask anyone who's re-decked a wood sun-deck with Trex!

Foam doesn't have any particular strength. It is just a filler / shape-holder to hold the composite in the right shape while it cures. It does help the composite stay where it belongs, but not much - that would depend on tensile or compressive strength of foam, and that is laughable, especially over years.

On something like a boat, which requires ballast to even hit its minimum desired weight, you just leave the foam or wood "forms" in place for life. This is also done in house construction using foam molds for concrete; the foam is left in place for insulation value and ease of attaching siding/drywall.

Where weight matters, one effective strategy in composite fabrication is to use a foam that dissolves in a solvent that does not attack the composite, e.g. The way gasoline will dissolve polystyrene but not some epoxy resins. Then wash out the finished product in the solvent, causing the foam to dissolve. In a modern industrial environment that would be recovered, separated and reused. This sort of thing is already done at foam-cup plants, which use pentane as a blowing agent for polystyrene.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.