But, was he in your house, like he was in mine?

behold the flowing lines of a Hurricane fuselage!!! Wait, something missing  I talked to a few people who felt that some of you have no idea what I meant by building the fuse on a jig - even after I put out the photos of the formers all cut out. With all the ARF's out there some have never seen construction.
Here are all of the formers placed on the crutch pieces, up on the jig. The jig is about 2 inches higher than it has to be - only has to high enough to support the fuse off the table enough to get under it a bit. For some reason the 3rd picture only opens in "image ready" and the psd files I have on my computer won't open at all.
With the formers clamped in place, I'll spend as much time as I have to to get everything lined up so the stringers are straight once i start gluing them in... with the back end covered in fabric there'll be no hiding a wonky stringer... and yes, i am using the laser...
Actually, at this point I find I buggered the jig for the front 6 formers - forgot the inset for the wing saddles to be glued to the crutch and inset in the formers....I'll get those jig parts fixed and be back...  I did say up front it was going to be a long build..
The 1/2 former is the back of the cockpit, and the former on the right is the dash/front....about 6" in front of that will be a "wing hold down former", then the firewall, but have to back and fix things before putting them on..

Yes it does look like your coming along.
When it's done you could make a book case for your RC rags
out of the jig! Double good!

And, firewall and former 3 now in place ( had to be there first and rest of formers loaded from the back, this done all off the jig )....once the formers were all there, along with the firewall, THEN I could put everything back on the jig.

I think former 10 is a bit too far to the front - would make the stringers not flow right....before I glue anymore I'll have to check that pretty carefully...

Once that is done, THEN the laser comes into play to try and ensure  everything lines up... for example, just sitting there former 4 is bent/warped/twisted  but  a few stringers will jam it into place..

all righty now.... need some help from you arithmetically inclined guys... like engineeeers and such (my math is limited to pie are round and cake are square (unless we're talking about the trajectory of a 170 gm .30 cal slug leaving the barrel at 2400cfm........) naw lets not go there)

This plane is reputed to build quite tail heavy, so part of my project is to keep as much weight off the tail as I can....SO; the plans call for spruce stringers, all 54 of them....

from cg back to tail is                  46"
from cg forward to firewall is            8.5"      - a ratio of  5.411  to 1

I weighed stringers of both spruce and balsa, pivoting them from a 46" spot to a scale and got

spruce stringer on scale                  9.5      gms            0.33509oz           0.02094      lb
balsa stringer on scale                  2      gms            0.07054oz           0.00440      lb
THEN
54 spruce stringers                  1.130976 lb            on the scale                  
54 balsa stringers                          0.238086 lb            on the scale      

So it seems to me I have a ratio of 5.41 to balance this weight at the firewall, which would be...            

spruce stringers need                  1.130976      x 5.411"      6.119711136  lb to balance
balsa stringers need                  0.238086      x 5.411"      1.288283346  lb to balance

So this tells me that using balsa can save almost 5 pounds of nose weight..... am I correct or what am I missing???? 

I was thinking several cages of "X'ed" CF rod between some formers would add a lot of torsional strength without much weight... man that 5 or so pounds is sure inviting....

I played with the numbers and came up with 4.83 pounds saved.  So either we are all wrong or your analysis is generally correct.  That said, I agree with Al; I wouldn't weaken the fuse too much.  I seem to recall reading something about the Me 109F or G where the tail section fell off during high speed maneuvers due to a weak empennage.  The solution in that case was to add two stiffeners to both side of the fuse just forward of the tail; ugly but it seemed to work. (I wish I could remember where I read that???)

In your case perhaps a mixture of balsa and spruce as Al suggested, and possibly some carbon fibre strips along the balsa stringers to address the tension component of the loads.  Torsional and compression loads will require a little more thought. A geodesic structure would probably work just fine....but then your Hurricane would look like a Wellington Bomber...not good!

Just thinking out loud.

thanks guys..... if I split the spruce and balsa half and half I save 2.4 pounds, and so the ratios go on and on and on.... thinkin'

best idea I've heard is spruce on the top 3 stringers, at #15 either side and then along the bottom for hanger rash. That will pretty well split it up harf and harf, saving 2 pounds and a smiggeon. 

Glen wrote on Apr 29^th, 2013 at 1:23pm:



yeh, I have that site bookmarked Glen.....but $225 just for a cockpit    I've owned planes that didn't cost that much