Re: [ULF-1] ULF-1 spar destructive test

From: Member 72
Date: 2018-05-02 17:00 UTC-04:00
Message: #0573

Hi Nuno,

Good luck with your
Build!  We deviated from the plans with the attachment fittings at the wing roots.  The plans call for tubular rivets to be used to attach the steel fittings to the spar caps.  We did not have the tooling to fabricate these large rivets.  So, at each station that required a rivet, we drilled a 1/2” hole and epoxied a nylon lug or bushing into the hole.  The nylon lugs have a 1/4” hole drilled down the center to accept an AN-4 aviation bolt.  We epoxied the steel spar fittings on, with their 1/4” holes pre-drilled to match the holes on the nylon lugs.  Then, we added the bolts, washers and nuts.  We were in contact with Member 9, the designer, at Aero in Germany.  Because of our deviation to his plans on the most heavily loaded part of the airframe, he asked us to perform a destruction test and gave us a minimum breaking strength.  Fortunately we were well over his minimum figure, and he blessed our design deviation!  If we were to do it again, we would consider using 1/2” phenolic rod rather than the nylon.  But, the nylon lug material worked OK.

Best regards,
Member 72

Sent from my iPhone

> On May 2, 2018, at 9:54 AM, Member 117 <[email]> wrote:
> 
> Good afternoon
> 
> I am preparing all the materials to begin the construction of a ULF-1 in Portugal, and I saw on the web, that the EAA Chapter 309 in North Carolina performed a  ULF-1 Spar destructive test, it is possible to have access to these data? and if the construction of the spar was carried out according to the instructions in the manual ?
> 
> thank you
> 
> Best regards,
> 
> Member 117
> 
> 
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