Fuselage plans - clarifications

Just now working on my new fuselage kit and would be grateful for some clarifications or even to be pointed to the right place in the plans/instructions.....

Here we go:

Intersection of top longer on and aft bulkhead F412. I could cut the horizontal web of the longeron away where it would go over the top of the bulkhead or I can modify the bulkhead a little - is there a right answer? I am wary of removing metal from that area of the longer on as the angle that will secure the VS has to bolt through it.

Dimensions ( in boat speak I guess it would be scantlings!!) for the various longhorns on the aft and forward fuselage. At least the main ones are clear - if only because they are so long! I'm guessing that all longhorns should be 1"x1", 0.125?? But does it say that anywhere?

Intersection of forward lower longer on that runs from the engine mount weldment back to F-404 - how does it intersect with F402? Looks like it should have a notch and adjacent joggle....

Firewall cutout for prop governor - anyone ever had any problems with the recommended cutout not being the right size/large enough? Does one size fit all?

So far I have the bulkheads (or formers if you prefer) clamped to the jig, with longhorns bent and ready to clamp in place, but need to resolve the F-412 issue and notch for the F-411 bars.

Many thanks for help.

Chris

Chris:

Only the longer on that goes from the tail all the way to the firewall is 0.125" thick. Other, shorter longerons in the tail cone are 3/4x3/4x0.063 angle. The long longerons is 3/4x3/4 as well IIRC.

Not sure exactly what you are referring to but in general I cut the bulkheads to fit around the longerons not the other way around. The longerons need to be full cross section their entire length.

You need to bite the bullet and buy a set of current plans....

Richard

Thanks - in fact these plans just came from Vans so they are as up to date as they can be!

I will go search the plans, diagrams and instructions again....

Chris

Hi Chris,

Looks like DWG #30 is where you want to be. My plans date back from the late 90's and show at least part of what you're looking for.

The F-412 is one of those back-to-back double bulkheads with forward and aft facing flanges. As the other gentleman pointed out, the main longeron is the heavier gauge 3/4 x 3/4 x .125".

At the VERY AFT end of this longeron, I trimmed the HORIZONTAL portion of the angle forward just enough so it stops right at the top of the F-412 bulkhead & I left the VERTICAL portion of the angle intact so that it extends all the way back to the end of the aft facing flange of F-412, where it goes into the joggle at the top of F-412. As you pointed out, there will be a cross-member angle (3/4 x 3/4 x .125") that bolts to the top of the LH & RH main longerons to provide an attachment for the Vert. Stab, thus you DO NOT want to trim the horizontal leg of the longeron too far forward of the F-412 center web. Another thing is that the AFT spar of the VS will sit flush against the AFT face of F-412, so trimming off the HORIZONTAL portion of the main longerons at the very AFT end will help give you clearance there for the VS spar. Clear??

See Dwg 30, in the view labeled Section C-C' (top right of page), there is a note which says: "Notch LONGERONS to FIT F-411 upright bars" That's what I did. If you think about the loads from the HS, it will not seem correct to notch those beefy .250" upright bars in a place so close to where they carry the loads from the Horizontal Stab.

However, at the BOTTOM of the F-411 upright bars, There is a DWG revision NOTE R6 which says to "Notch Bulkhead and F-411 bars" to accommodate the horizontal portion of the LOWER longeron. THAT lower longeron does not run the full length of the plane (stops at F-407 if I recall); that longeron is 3/4 x 3/4 x .063", as are the other longerons in the aft tail-cone portion of the fuselage.

I can't answer the firewall cut-out question you had. I didn't make that cut-out in my firewall as I have no plans to use a Con$tant $peed prop or the governor; just seemed like unnecessary work for my simple sport plane mission.

Hope I added more help than confusion.
If its any consolation, I found the fuselage to be one of the more challenging parts of the build; lots of little things to think through and resolve (part of the fun if you ask me!)

Best of Luck with your project!

Thanks for that. I've done exactly as suggested for the top longeron/F412 intersection.

Other info I needed I finally realised was on drawing 26.

I now have the bulkheads jigged, longerons bent, and am now carefully measuring everything several times before drilling any holes.

I'll put some pictures in the "current status" thread tomorrow.

Chris