Difference between Mylar and hard copy plans

[T-bird]

Hi
I have just received my Bearhawk Patrol plans in the post. I have scaled the plans up to 1 :1 and compare it to the Mylar for the nose rib. The nose rib fits perfectly but
the center of the front lightning hole in the nose rib is 1/4 inch lower on the Mylar than on the scaled up plans.

Do I accept the Mylar or the up scaled hard copy ??

[Chris In Milwaukee]

Definitely the Mylar, in my opinion. Use the plans as the "instructions", but use the Mylar as the source of truth.

[T-bird]

Thank you Chris.

This will sort out the location of the lightning holes.
The next issue is that I can't find the dimensions for these holes.
If I scale the plans up I get 1.5 inch for the first one in in the nose 2.625 inch second one in nose rib.
In center rib from nose side 3.2 inch 3.2 inch and 2.75 inch.

Are the sizes correct ?
Would it be possible to standardize 4 of the 5 holes ?
It would save time having one flaring tool.

[Chris In Milwaukee]

The mylar should have the location of the lightening holes as well, so that makes that part easy. The plans for that page are 1:2, so the first nose rib hole is 3" in diameter, 5.2" for the second. 6.4", 6.4", 5.5", then the oval hole for the center ribs. If you don't have one, definitely run down to your local office supply store and grab yourself and engineer's scale (they measure in 1/10s of an inch instead of half/quarter/eighth). Then you can flip to the "10" (1:1) or "20" scale (1:2) and get very accurate measurements off of the plans. Those are pretty much the only scales that Bob uses, or a multiple of that. Full-sized wing and fuselage sheets are 1:20, so the "20" scale on the ruler works the same.

If you use some of the same methods that many of us have used over the past few years, there isn't a lot of benefit, really, to cutting the holes the same size so you can use the same flaring tool. A 6" flaring tool from the racing supply shops is crazy expensive, even more so if you buy a set. But to answer your question, no reason you couldn't standardize on a hole size, choosing the smallest of the set. It will add a bit of weight since you're leaving metal behind, but probably not much more than a pound or two per wing. But if you're picky about your finished weight, then the more metal you leave out of the wing, the lighter you'll be.

Have a look at these two threads outlining my experiences with the wing ribs to see how I did it. I used a lot of the techniques that others have used before me, and added a twist here and there where it made sense for my building environment:

http://bearhawkforums.com/forum/bearhawk-patrol-plans-build/19435-having-a-rib-party

http://bearhawkforums.com/forum/bearhawk-patrol-plans-build/21676-fluting-party

​Also, there is a great video reference set from N3UW (John Snapp) that reallly brings clarity to the process. I used many of his techniques in my building process.

https://www.youtube.com/user/n3uw

Welcome to the group! And most importantly, have fun! Feel free to ask questions. Plenty of people have been down this road, and we're all excited to help you out with your build.

~Chris

[T-bird]

Thank you Chris. I think we are on the same page my measurements are raduis and yours are diameter.

Your Rib party inspired me to take the leap and order the plans.

[Chris In Milwaukee]

Fantastic! I'm honored that I was able to help you decide to buy plans. It will be a great adventure for all of us.

And don't let utter perfection be the enemy of time. Build smart and build safe. If it looks messed up, it probably is. If it looks good, keep moving.

Someone once told me, "You're building an airplane, not a watch."