tasesq

Hi All,

I am trying to design an aircraft with a swept wing and am thinking of using a carbon fibre telescoped spar.

From searching the web, it is hard to find spars that fit into each other perfectly.

I was thinking of the following:
OD 20mm ID 18.60 for inner spar (as it is stronger)
OD 10mm ID 8mm for middle spar
OD 5mm ID 04mm for outer spar (where wing is thin).

Does anyone have any opinions on this? I was wondering the best way to join these tubes (aluminium bushing to fill the gaps??) and also what people have used on similar models to this size.

It will be about a 2m wingspan EDF with probably 110mm stumax fans.

Also -how to i get a spar like this to transmit loads to the fuselage? (it seems that floating spars in the wings with no physical attachement to the fuse other than through the ribs and a wing joiner tube,is awaste of time as it does nothing to add strength to the airframe, only to keep the shape of the wing???)

I was also wondering, does anyone have any ideas about incorporating a CF tube wingspar, with an aluminium inner tube going through the fuse as a wingtofuse joiner? The problem is that with the wingsweep, i would have to cut and weld an aluminium spar to suit, and with a bend i was worried about turning forces etc... I.e. cut/weld it in a splayed out "U" shape.Like: /\ (kind of!)

Pics of the wing and the spar idea are attached.

Note - the wing will be built upside down (the building tabs on the image are on the top of the ribs).

Thanks - sorry if the questions don't give enough information - if anyone has worked on a design like this one i would love to get some of your design principles..

tasesq

I am also happy to PM anyone the sketchup file if they would like to take a closer look at what all my above ramblings were about!!!

RCEEBUILDER

It seems a good idea. I would use two tubes OD 20 and OD8  side by side  .In my opinion no need to extend the tube to the tip ribs.