Cantilever (no struts) Carbon Fiber Wing shows greater than -4G test load

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Belite R&D Ultralight Aircraft sneek peak:

Here’s what you can do with a one-off carbon fiber / titanium wing design (combined with some great chromaloy steel work on the fuselage).

What I am showing you is a Belite research project:  a fully cantilevered, strutless wing design, built using a 24 pound carry through carbon fiber spar (a fully custom, 4 inch diameter monster carbon fiber tube, with about
6 or 7 layers of carbon fiber), along with a combination of 6061T6 aluminum spar reinforcements and some titanium spar carry through reinforcements, just for grins.  The wing is designed to take a test load of greater than 4Gs in either positive or negative G’s.

The wing design is destined to be shown off in a future Belite FAR Part 103 Ultralight Aircraft.

A picture is worth a thousand words, so we loaded the wing with over 2200 pounds of sand and iron weights, in a negative G configuration, and took some pictures.  This shows the strength of the wing, and also the strength of the fuselage.  The fuselage was modified from our standard design to handle the spar carry-throughs, and also to handle the greater than 4G negative crush load.  (Positive G’s are a lot easier for the fuselage to take.)

Can you do this with your old fashioned ultralight wing?  I think not.  Enjoy looking at the pictures.

Adding weight, about 210 pounds per rib:

Fully loaded wing, around 2300 pounds (including intrinsic weight of wing):

Photograph showing air space between wing and safety support.

View from other side of shop:

View of center, showing massive carbon fiber carry through spar.  Some of the fuselage modifications to support cantilever wing load are also visible on the front carry through spar.

Belite R&D:  The most innovative in ultralight aircraft engineering.

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4 thoughts on “Cantilever (no struts) Carbon Fiber Wing shows greater than -4G test load

  1. From a design standpoint, tubes are difficult to work with as spars because they tend to buckle. Take a soda straw and bend it quickly and it will form a crease or smile where it buckles. For an aluminum spar, this is what would happen. For a composite one, it will probably just break. Have you thought of filling the tubular spar with foam? This would greatly stiffen it without adding much weight. This would be similar to the original "sparless" wing designs proposed by early composite builders. Probably could use builders spray foam. I've never figured out why builders don't use foam to fill then ends of aluminum tubes. This would keep out moisture, oxygen and bugs.

  2. This is amazing! Nice Work. I was wondering if you experimented with carbon ribs? if so, how much weight savings did you gain, and how much lost/gain is strength would you get with carbon ribs vs aluminum?

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