Re: [ULF-1] Reconcile Rear Fin Spar Widths with Loft Diagram

From: Member 72
Date: 2012-06-06 22:26 UTC
Message: #0376
Andy,

Thanks very much for pointing out why rib #1 is so much shorter in the loft diagram.  What I meant was that when you measure the widths of the ribs on the loft diagram, where they connect to the rear spar, these dimensions do not seem to match up with the width of the rear spar at the stations where these ribs attach. The width dimensions of the rear spar, as shown on the drawing, do not match up.  They are not just a little off.  Now, I know when you build up each spar, you have to "fine tune" the distance between each cap strip, so that the ribs match up perfectly to the attachment stations when they are glued on.  Otherwise, of course, you end up with ribs not fitting to the spar properly.

We are still scratching our heads over this one.  We are prepared to re-draw the rear spar plan to get it to match up with the rib widths as shown on the loft diagram.  We are treating the loft diagrams as a "given" that cannot be altered.

Member 67


---- Member 50 <[email]> wrote: 
> Member 67, Have you taken into account the doubler built into the fin rear
> spar where it is attached to the fuselage. This is through the position of
> rib one (base rib) and effectively takes up the space of the rear of the
> largest fin rib, it means the rib is shorter than it would be if the doubler
> was not present.
> 
> Andy Member 50
> 
> 
> 
> 
> 
> -----Original Message-----
> From: [email] [mailto:[redacted]
> On Behalf Of [email]
> Sent: 06 June 2012 03:26
> To: [email]
> Cc: [email]
> Subject: [ULF-1] Reconcile Rear Fin Spar Widths with Loft Diagram
> 
> Folks,
> 
> Our rudder and elevator spars are built.  We are starting on the fin spars
> and have planed the spar caps to their double taper as per plan. 
> 
> We are having difficulty reconciling the width of the rear spar plan drawing
> with the rib widths on the loft diagram.  The widths of ribs #1,2,4,6, and 8
> on the rear fin part of the loft diagram do not match up at all with the
> width of the rear spar drawing at the respective rib stations.  In fact,
> they are way off. The front spar drawing seems to be OK.
> 
> Has anyone noticed any discrepancies in the rear fin spar drawing??  My
> build team and I are quite perplexed by this.  Should we just modify the
> rear spar plan to match up with the rib widths shown on the loft diagram??
> 
> Many thanks for your help,
> Member 72
> 
> 
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