I weighed what it would take to build the number 1 rib like the rest (internal ribs and corner gussets both sides and it was 71.2 grams dry (not glued up). The number two rib was 68.3 grams dry. I used that materials the plans call for, and that was 5/16 square caps with 1/4 x 5/16 internal bracing
From: Philip Lardner <This email address is being protected from spambots. You need JavaScript enabled to view it.>
To: 'Rick Mullins' <This email address is being protected from spambots. You need JavaScript enabled to view it.>
Sent: Sunday, March 18, 2012 6:48 PM
Subject: RE: Carbon Dragon rib weights
It would be great if you could knock up a couple of ribs for comparison - say a #1 root rib (1/2" x 3/8" caps and 3/8" x 3/8" internal braces) weighed without the 1/32" plywood skin and then (for comparison) with the 1/32" skin. If you could also knock up another rib, say #8 from the root that would be very useful also. It would be important to include all the plywood join gussets as per the plans to get an accurate weight. In the moulds I have made, I am reducing the depth of the rib caps and struts by 2mm at each rib outboard of the root rib which is 24mm deep, until I get to rib #8 at 10mm deep. Ribs #8 - #13 are all 10mm deep. My #13 tip rib weighs in at a hefty 21.1g - sneeze and it blows away!
Actually, you wouldn't even need to glue up the ribs - just cut the bits to the correct dimensions and weigh them. I'd guess there's not much more than a few grams of glue involved in each rib. If you can measure to 0.1g accuracy that would be ideal, but if not, then the nearest gram will do!
Thanks,
Phil.
From: Rick Mullins [This email address is being protected from spambots. You need JavaScript enabled to view it.]
Sent: 18 March 2012 11:09
To: Philip Lardner
Subject: Re: Carbon Dragon rib weights
No, I didn't weigh any of them. It wouldn't take long to throw one together. I might do that as I would be interested in the difference also.
From: Philip Lardner <This email address is being protected from spambots. You need JavaScript enabled to view it.>
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Sent: Friday, March 16, 2012 7:51 PM
Subject: Carbon Dragon rib weights
Hi Rick,
I've just been looking through your construction photos and I see that you have made your wing ribs out of spruce and ply, as per the original specification. I don't suppose you measured the individual weights of your ribs before you glued them to the spar? If you did, then I'd be really interested to compare your weights with my carbon/foam ribs to see if I'm winning or loosing the war on weight!
Thanks,
Phil.
