semi cantilever wings

[andyb79]

i am looking for some help with a question i have been given as part of my college course.

the question is "in a light aircraft, what is a semi-cantilever wing, how is attached to the fuselage?"

i have been through all of my notes and several books as well and cant seem to find any more than passing references to them.
the best i can figure this is the type of wing that is fitted to smaller cessnas eg 150,170 etc? or am i way off with this and what would bethe technical answer to the question or any suggestions where i could find the answer

any help would be greatly appreciated

[noisy]

Hi Andy,

A semi cantilever wing is the type of wing fitted to small Cessna a/c, as well as some others e.g. Shorts 330/360.
This is where part of the loads placed on the wing are channelled into the structure via a strut. This triangular structure is theoretically incapable of bending. In practice, the strut will flex somewhat under the imposed loads. Remember that in this case the strut is a tension member as opposed to being compressed.
On the C152 the strut disappears into an aerodynamic fairing. I guess it must be bolted on or held with a pin. It consists of the actual structural member with an aerodynamic cover over the top.

At the wing root, the wing might be simply bolted on or it may be held on with interference fit pins. This method sometimes relies on cooling down the pins with liquid Nitrogen or similar. The pin is driven home and warms up in the ambient temperatures, expanding and producing a very tight fit.
Somebody help me out here?!

Look at the case of the Cessna 177. This aircraft was designed to replace the C172 over thirty years ago. We can all see what happened there! The Cardinal has a pure cantilever wing with no struts, which improves fuel economy, gives increased speed and greater range etc. Without the struts, the wing has to be stiffer and heavier in order to withstand the same flight loads.

http://www.flyer.co.uk/cardinal.php

Also see Airframe Structural Design by Michael C.Y. Niu
Hope I’ve helped.

Noisy

[andyb79]

thanks

and just to make this post up to 15 characters i will add that there is something that just doesnt look quite right about that cessna 177 not having struts

[xelophab]

andyb79, I agree it just does'nt look right. The reason I think it is because it has very laminar wings, which I beleive would need less drag from the airfram, hence no struts and retractable gear. The whole thing from the side looks more laminar than your average cessna, even the Grand Caravan.

Well that's my 2 cents for the millenium
! :P)

[DubTrub]

The whole triangular assembly is classified as a pin-jointed structure. Bolts are used at each of the three connexion points.. This applies to Cessna, Piper, and all the strut-braced monoplanes (and biplanes for that matter) that I can think of.