Fokker Dr I structrutal wing failure

[Ricardo Reis]

Hi all

Sorry if this has already been treated here but could only find the reference to the Fokker DR.I in the aircraft section. I've read in an article wrote for Fana de l'Aviation (a french magazine) that the wings of the DR.I where very strong and didn't need the usual outer struts between the wings. Basically it was said they where put there because of pilot trust in them, they weren't structurally needed. In the DR.I page here several wings failures are referred and I find both affirmations to be contrary. Can someone shed some light in this (or some pointers?)?

very grateful,


[EDIT] I did the homework (which I should have done first) and checked the wikipedia article on the Dr.I. wing failure was due to poor workmanship during construction and bad aerodynamic load balance between wings. The article in Fana was about the wing construction itself.

[crankcase]

... longish thread on this very subject. Can anyone locate it?
marc

[Ricardo Reis]

Originally Posted by crankcase

... longish thread on this very subject. Can anyone locate it?
marc

you're refering to this one? Fokker Triplane V.4

just found it

[Laserlloyd]

Hi Ricardo Reis:

Basiclly, Voss had tested the V4 without the outer wing struts. He experienced the wing fluttering or vibrating during the flight. I beleive from this information Fokker had added the wing strut.

I do have information in a couple of my books at home but I'm on the road this week and don't have access to them until the weekend. Taz and Dan-San should be able to help on this to.

Lloyd...

[Ricardo Reis]

From elder posts I've understood now that the DR.I had a cantilever wing design. I don't think this is should be very usual at the time, are there other examples of such option? Cantilever wings only become common place in the late 30s...

[Dan_San_Abbott]

Ricardo Reis:
The wing spars of the Fok.DR.I were strong more than strong enought for any flight load the Fokker Triplane would ever experience in air combat.
1. The joint between the rib and and the aileron spar was an inadequate design.
2. The joint between the the rib cap strip which was dadoed shallow grove into which the the rib webs were inserted and then sercured with glue and brads nailing the capststrip to the thin plywood webs.
3. The fabric was attached to the ribs with tacks which caused splits in the capstrips.
4. In the manufacture of the wing the wood structure of the wing was inadequately varnished to prevent the absorbsion of moisture in the wing structure.
5. The ailerons were over balanced. The failures occured in fast hard turns, when the aileron began to oscillate. This resulted in the failure of the rib connections to the aileron spars, the failure of the rib structure of the capstrips and web connections and the loss of the covering fabric.
I am sure you will get other responses that differ from mine.
Blue skies,
Dan-San