Wood spar data


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Well-Known Member
Aug 23, 2004
Ottawa, ON, Canada
Hello everyone, I need to tap into the vast experience of all those who subscribe to this forum.

I am looking for some “historical” data on wood spar dimensions for aircraft in the 2000lb-2400lb gross weight range (must be for aircraft with wood spars – preferably high-wing with struts, like the Fairchild 24).

I have some data for a number of lighter aircraft, but nothing in the weight range I am looking for (I can share this info if anyone needs it).

The reason I am looking for this information is because I have designed a set of wood spars (front and rear) for an aircraft, and I would like to confirm my design and analysis using data from other aircraft of the same species.

Thank you


Well-Known Member
Oct 20, 2003
Northern NSW Australia
The best way to get data on your designed spars would be to build two and test them mechanically.
Secure one at the root and load it up with sandbags to destruction, recording the weights. Do the same with the second.
I'm not exactly sure of the method of doing this, but if I have the gist of it, one layer from root to tip, and load up each other layer from the root to slightly futher from the tip each time to more accurately reflect real loadings which increase closer to the root. Please someone jump in here If I have this wrong.
The last weight recorded before failure divided by the gross weight of the airframe will give you the G rating, loading it on top will give a -ve G reading turning it over and loading the bottom side the +ve reading. (at least that's how I understand it)
Therefore a recording of four times the gross weight will give a G rating of 4G (I certainly wouldnt want to fly in an aircraft that had a max wing loading of 4G's that for sure)