Phil, Looking fine! Not long till you fly I would guess. Realm is not much toward completion lately but last night calculated spruce needs for flaperons since I am going to rebuild these. Curious what your Flaperon ribs weighed in total both wings?

Keep up the good work....

Gus

Thanks Gus!

I'm not sure I weighed the flaperon ribs on their own before installation, but they were extremely light - all my ribs are!! I will say one thing, however, my flaperons are VERY stiff - I think I could have made them much lighter by using lighter carbon cloth - I used 200gsm carbon over 5mm foam cores. The flaperon spars are made from two layers of 200gsm carbon with a single pultruded carbon rod encapsulated in each spar cap.

My flaperons weighed in at a shade over 8lbs each. You can find some of my final weights here: www.ihpa.ie/carbon-dragon/index.php/foru...rbon-cd?start=42#936

The difference in weights (L / R) is down to the amount of residual epoxy/cotton flock mix that didn't get scraped off one flaperon before it set too hard to be easily removed. This has been a constant bane for me - epoxy/cotton flock (used to glue ribs and D-sections to spars) accounts for a significant proportion of the overall weight of the different assemblies. Particularly with the D-sections, you need to use more than you think to ensure a uniform bond in parts you can't reach (i.e. inside the leading edges) and the excess can't be removed unless you have supernaturally long arms!

I'm getting very close to finishing at long last - I'm working out how much Oratex UL 600 I need to cover the wings - exciting!!

Phil.

Trailer nearly completed...





...just the back doors to make today and finish off the wheel arches.

Phil.

Wow - it actually fits!!!



I'm busy prepping to cover the wings now - barring any further distractions, I might just get to fly it this summer!!

Phil.

Rough day at the office today - I load tested the wings to 5g and... something went CRUNCH!!!

The good news is that the wings performed very well, with the leading edges exhibiting minimal oil-canning.

The not so good news (well, ok - the bad news!) is that the spar buckled in compression at the very centre of the wing

Looking on the bright side, I'm delighted it failed on the ground and not in the air!!

Here's the general set-up:



Two lengths of angle iron (40mm x 40mm x 4mm) are bolted to the fore and aft wing attachment points. The wing is then suspended on lengths of 8mm threaded steel rod to two more lengths of angle iron supported by two lengths of 100mm x 100mm wooden beams, which themselves are supported by two 44 gallon drums. NOTE: The orange straps are only there to save the wing from falling to the ground in the event that one of the attachment bolts fail - the straps are not tight and do not affect the load test.






The wing tips are supported by two scissor type car jacks, which have about 12" of travel.

...more photos in the next post...

The wings were leveled up spanwise and then tilted to 10° to simulate a pitch-up manoeuvre. Each side of the wing was loaded up with 251kg (553lbs) of sand bags (502kg / 1106lbs in total) while supported by the car jacks at the wing tips - with the following load out:

Wing Panel Panel Load
Rib 1 - 2 65.64lbs 29.77Kg
Rib 2 - 3 62.08lbs 28.16Kg
Rib 3 - 4 58.52lbs 26.55Kg
Rib 4 - 5 54.96lbs 24.93Kg
Rib 5 - 6 51.40lbs 23.32Kg
Rib 6 - 7 47.85lbs 21.70Kg
Rib 7 - 8 44.29lbs 20.09Kg
Rib 8 - 9 40.73lbs 18.48Kg
Rib 9 - 10 37.17lbs 16.86Kg
Rib 10 - 11 33.61lbs 15.25Kg
Rib 11 - 12 30.06lbs 13.63Kg
Rib 12 - 13 26.50lbs 12.02Kg
Total: 552.81lbs 250.76Kg




In the last two photos you can see that the lower spar cap (actually the top spar cap, but the wing is upside down) has buckled in compression *right on the centre line*. There is no other apparent damage visable to the wing, which leads me to believe that the wings can be fairly easily repaired.




The centre section of the wing spar (between the two #1 ribs) comprises two horizontal load transfer bars of solid carbon (5mm thick x ~25mm deep x ~420mm wide). Two more load transfer bars (similar dimensions, but shorter) run vertically, to which the pod/wing connection fittings are bolted. The space in between these four solid carbon bars is filled with 5mm foam board, covered by several layers of carbon cloth. This centre section shows minor damage.

The spar cap flanges between the two #1 ribs is only 10mm deep and is, in painful hindsight, woefully too narrow to carry the loads unsupported by the leading edge. I think that by bolting a pair of 10mm x 50mm x 420mm thick aluminium plates fore and aft of the spar cap under compression that this should make this section of the spar caps much more able to resist compressive buckling. The other spar cap (under tension) showed no signs of any damage, but I plan to reinforce it with a single, similar aluminium plate just in case!



I hope to have the repairs made and aluminium plates installed by Tuesday and will re-test the wing again. Fingers crossed!