HK foam cannot support a wing without reinforcement?
Just as an experiment I built a 40" wing (2 x 20" panels) from 5 mm underlay foam (green but the same as HK foam)
No structural reinforcement apart from tiny balsa leading and trailing edges to give a bit of 'ding' resistance.
The completed wing supporting 18 oz (510 g) when supported just by its tips.
[ATTACH=full]55595[/ATTACH] Yes it bends a bit but loaded like this creates a stress at the centre equivalent to a uniformly distributed load of at least twice this weight.
The completed wing on my 'hack' pod and boom pusher fuselage which uses a 150W out runner and a 1500 mAh 3s LiPo.
I am sure I could break it if I try hard but it is fully aerobatic and has not failed so far!
I fly parkjets
So the only built up wing I can make is a KF2-4
I found iam really limited to 28-30 max wingspan for these wing platforms