Hi Bill,
The model is looking great!
Question on I-beams; When Bob built his USA-1 he said the wing got a little thinner than he wanted when final shape sanding it. Do you make your ribs a little bigger dimensionally, sand less, etc to make sure the airfoil doesn't get thinner?
Thanks man,
Chris...
Hi Chris,
I don't make any real change to the ribs, but I mount them just a touch *proud of the LE and TE so that I can blend them in while shaping the to *edges*.
As to the USA-1, the original plans I had were too "shallow" in the spar height to make the ribs work right, so the four we have built here, and those I have talked to about it, I have suggested adding 1/8" cap strips to the spars so that the actual airfoil can be achieved. If done as my plans showed, the ribs had to be forced down to meet the spar by about 1/8". You *could* make the spar 1/4" deeper and not worry about it. I have not seen the plans that MA has that were with the article, mine were the early ones I got from Billy/Warren. The rib template is correct, but the spar dimensions were not.
With the *cap strips* the ribs went on fine and you can shape the cap strips as you are supposed to on an I-Beam plane. I had already done one bottom panel on my first one when I called The Man and asked him if I was supposed to have to push the ribs down so far just for them to meet the spar. It was putting a *U* shape in the ribs!
Bill