Chapter 14 – Mounting Spar to Fuselage

Chapter 14 – Mounting Spar to Fuselage

16 September 2016 — 
Today I hit another HUGE milestone in my Long-EZ build:  I mounted the fuselage to the CS Spar/Wings assembly!

First, I spent about an hour organizing & cleaning the shop.  I then spent over 45 minutes cutting the BID tapes for securing the fuselage to the CS spar.  I also cut out the 3″x3″ BID pads to cover up the inboard 5/8″ pilot holes I drilled on the CS Spar to facilitate drilling the wing bolt holes.  Since the front face of the spar makes up the aft wall of the fuel tank, then the inboard holes clearly need to be re-glassed.

Fuse to spar BID tapes

To get the fuselage into place on the spar, I needed to get rid of the sawhorse out from under the spar.

Removing spar sawhorse

To do this with least amount of hassle and disturbance, I simple cut the 2 front legs of the saw horse.  Since I had routed the water level lines through the legs of the saw horses, the most expedient way of freeing the water level tubes was to simply cut the cross members of the sawhorse.  You can see all this in the pics below.

Voila!  Here’s the saw horse with its front legs trimmed down and easily removed out from under the spar without disturbing the spar.

Removing spar sawhorse

Here are the wings & CS spar, with the spar out in free space and held in place only by the wing bolts.

Spar sawhorse removed

I then needed to get the fuselage out to the wings/spar setup.  Here’s my fuselage on climb out! Of course I really lifted the nose high to get the table out from under it.

Aim High!

This is the first time my fuselage has ever ventured out into the world (aka “beyond the garage”).

Pulling out the big guns!

Looks “long” with that nose on there.  Love it!

Mobile fuselage!

Getting ready to back ‘er up.

Fuselage on the move!

Doing a little 3-wheelin’!

Traversing narrow paths . . .

Over the storm drain & through the woods . . .

Through the woods . . .

Ah, this is where this belongs!  Looks awesome with the fuselage set in place on the spar. It was pretty EZ to line it up because I had taken some time when I mocked this all up in Germany back in 2013 to align the fuselage on the spar, at which point I marked the spar with alignment lines.  I had actually forgotten about those alignment lines and seriously didn’t even notice them until today.  What a nice surprise!

Spar glassed to fuselage!!

Spar is still level Left & Right.

Checking CS spar level

Here’s me re-checking the CS spar level, left & right sides.  I don’t have pics, but the incidence on top of the spar looked spot-on as well.

Checking spar vertical levelChecking spar vertical level

Ah, nice & level across the longerons!

Checking longeron level

Now, the nose was a bit high so I ran into the garage, got my battery and mounted it in the nose.

Checking nose level

I then raised the nose gear until the longerons were level at 0°.

Ah, better!

Then rechecked the left longeron to confirm 0°.

Verifying other longeron

I tried to use the laser level to shoot down the CL of the fuselage, but it was just too bright out to see the laser mark, although I could see well enough to line up the spar with the back of the front seat CL mark.  I then ran a string to confirm all was centered between spar & fuselage.

I do have to admit that a persistent problem that has plagued me all these years is that my fuselage has a slight twist to it.  It essentially “droops” down to the front left just a hair.  It’s about 0.2° low on the left side at F22.  There’s nothing I can do about it, and I even tried to load up the fuselage with offsetting weights to cure (pardon the pun) this problem when I post-cured the fuselage, but it made scant difference.  The main issue it causes is with mounting the canard, and it simply means that the canard may be lopsided a hair when mounted to F22.  However, we’re talking about the canard being mounted maybe 1/8″ higher on the left side.  This issue is one major reason why I want to mount the canard with the wings & spar in place so that it will be straight in relation to the wings!  Not a horrible issue, just one to note.

Checking spar/fuselage centerline

All-in-all, it only took me about 30 minutes total to align the fuselage with the CS Spar.  In addition to the steps above, I made a whole slew of measurements from the aft outboard corner of the spar to instrument panel & F22.  Measured from the front outboard end of the wings to the the panel & F22.  I also measured the aft outboard TE of the wing to the very tip of pitot tube: 247-3/4″ on the left, and 247-1/2″ on the right.  I looked at all my other measurements and noted that indeed my fuselage was tracking just a hair to the right.  A very small nudge on the nose and all my measurements were pretty much exact, if not within a 1/8″ of an inch off at a point or two.  I remeasured from the aft outboard TE of the wing to the pitot tube and got a perfect 247-5/8″ on each side.  It was clearly time to get down to brass tax and get this fuselage mounted while my fuselage-spar alignment was spot on!

As I started the actual attachment process, one thing that I had going on –since I made the spar cutouts on the aft fuselage exactly to the plan’s dimensions– is the foam on the fuselage is higher than the spruce firewall/gear hard point (LWY).  I could just fill this area with flox, but I’d rather use a thin piece of spruce as a spacer. I measured the gap at  0.150″.

Gap under CS SparGap under CS Spar

I grabbed a good piece of scrap spruce and then set up my saw for right around 0.150″ (or ~5/32″).

Cutting under-spar spacers

And made two 5.7″ spacers to go under the spar.  I would have preferred 6.5″ long spacers, but this piece of spruce was the best I had available, so I used it.

Under spar spacer

In prep for glass, I sanded all the areas that would be getting BID tapes.

Sanding in prep for glassSanding in prep for glass

I then laid up the BID tapes!

My fuselage & CS spar are now officially one assembly!!

Spar glassed to fuselage!!

I’ll of course wait to layup any glass on the inside longerons until I mount 10-ply BID pads for the engine mount extrusions.

Spar glassed to fuselage!!

And here it is, the wings mounted to the CS Spar now mounted to the Fuselage!  Yes, it’s bit cluttered around the plane, but I’m in the process of building it . . . if ya haven’t heard! ha!

Also, for those folks concerned about me not using a sawhorse up front and relying on that “squishy” front tire to maintain the fuselage level, it did fine.  To account for that, I used fast hardener –which let me tell you, is fast!– and worked in phases starting from the bottom spar connect points moving upwards.  I also rechecked the level and center measurements a number of times.  Hours after I was finished it was still sitting at 0º on the longerons.

Spar mounted to fuselage!

[The steps below are technically Chapter 19 and are shown there as well] I then cut the inboard 5/8″ pilot holes on the spar –used for drilling the inboard wing bolt holes– out to 1″ since the edges of the 5/8″ pilot holes were really oily & dirty from all the metal shavings & the spotface pilot rod rubbing against it.

Recutting inboard but holes for glassRecutting inboard but holes for glass

Here are my 3″x3″ pre-pregged 2-ply BID pads, and the 1/4″ foam I used to back fill the holes.


I don’t have any pics yet, but I micro’d in the foam into the holes and then glassed up the 2-ply BID pads over the holes. It was dark and I really couldn’t get any decent pics of this, so I’ll get them tomorrow.

I then set up a heat blanket & a couple of heat lamps on the new layups.


17 September 2016 — Today was a light work day since I’m heading out to Dulles for the annual Airplane Pull & aircraft display.  I spent over an hour cleaning up the surrounding area around the airplane (I think I can say that now!).

I wanted to get a pic of what I didn’t last night, and that’s of the inboard holes filled with foam & micro and then glassed over with 2 plies of BID.  You can see that this is the initial shot & exactly what I saw when I pulled the heat blanket off for the first time.

Cured Fuselage-to-Spar glass

Here’s a shot immediately following me pulling all the peel ply.  I haven’t cleaned up the layups so it’s all stiff a but rough.  I am, however, very happy with the quality of the layups.

Fuselage/spar peel ply removed

Since I found out last night that we may have a chance of thunderstorms this weekend, and I’ll be very much out & about, I decided to really ensure that the tarps were secured well to keep the sun off the raw composite surfaces, and to minimize any moisture… especially in the nose — which I covered with plastic.

Fuselage-Spar-Wings Covered


18 September 2016 — This evening I wanted to check how the fuselage longeron angles were looking.  Since there’s been some fairly significant swings in temps with the weather over the past couple days, I was curious to see if it had affected the front tire at all.  It didn’t and the fuselage is still locked at 0°.

Rechecking longeron level


19 September 2016 —  Today I wanted to temporarily mount the firewall, which required the trimming of the end glass hanging from the layup I did to mount the CS Spar to the fuselage.  I marked the glass, as you can see in the pics below, in order to have a reference line while cutting the glass.

Fuselage-spar glassFuselage-spar glass

I then used the Fein saw to trim up the dead glass.  After trimming the glass, I hit the edges with my sanding block.

Trimmed fuselage layup

It was then time to mount the firewall on the fuselage.  Uh, just one slight issue.  When I marked up the CS spar with the fuselage attached back in 2013, apparently I did it with the firewall off the fuselage.  Thus my lines were a hair farther out (say, 0.03″ to 0.04″) than if the firewall had been mounted in place. Doh!

Firewall temp mounted

Well, it was fairly tight, but with the help of a “persuader” (rubber mallet) the firewall went back on. Besides my one little spacing SNAFU, everything else with the firewall looks fine!


22 September 2016 — Below shows the final fuselage mockup with the upper cowling.  I’m posting these pics on this page since the CS spar is integral to all of this.

Test fitting upper cowlingMocking up upper cowlingBreaking it all down!One last shotBreaking down wings & fuselage







Removing wing bolts:

Right wing bolts outLeft wing bolts out!

Wings detached

Wings unmountedDelinking from the mothership!

Moving fuselage back into shop:

Movie' on!We have separation!Tight fit! How'd that happen?!Cruz' in style!Puttin' 'er away!The Eagle is in the Roost!

Tight squeeze, but it all fits!

It all fits! (barely! ;)

Side yard is back to normal!

Empty space... again.


10 October 2016 — You’ll quite often here me refer to the “sins of the past” in regards to the build coming back to haunt me in various ways.  Although, there’s an often number of times where a “mistake” turns out to actually be serendipitous in that it’s better for my specific build or better meets my requirements.  Case in point is when I cut the GIB seatback Spruce hard point LWX at the plans 35° on my saw, which in reality should have been 55° on my saw for a more acute angle.

When I lined everything up on the numbers, this is what created that small 0.15″ gap between the fuselage sidewall foam (underneath the CS spar) and LWY when I was mounting the canard.  It also resulted in there being a slight gap betwixt the GIB seat back and the face of the CS spar.  No worries though, since I actually want my GIB sitting more upright, and although this is a very minor difference in angles, the seat back is slightly more vertical than before.

Of course now I have a gap I have to contend with.  Again, no worries.  I just grabbed a long thin scrap piece of Divinycell foam and sanded to shape to fit in the channel between top seat back and the lower face of the CS Spar.

GIB seat back & CS spar gap

I then whipped up some micro and micro’d it in place.

GIB seat back & CS spar gap filler piece

Then let it cure.

There is actually a secondary gap between the aft side of the foam filler piece and the dip inward of the glass on the bottom edge of the race-track looking hole in the front of the CS Spar.  Again, I think this might turn out better since that edge can be a bit of a snake pit just waiting to bite unsuspecting forearms as your leaning forward, a bit off-balance either trying to stuff stuff into the spar for storage, or when holding a wrench while mounting the inboard wing attach bolt.  Thus, I will fill in the secondary channel with pour foam and then shape a smooth bull-nose type transition in prep for 2-plies of BID.

GIB seat back & CS spar gap filler piece


11 October 2016 — Here’s the pour foam application on the back seat / spar junction where there was still a slight gap after I embedded a foam wedge/spacer in between the seat back & spar.

GIB seat/spar junction filler foam

And a closeup shot of the pour foam…

Closeup seat pour foam

I then sanded the entire foamed area and the glass areas that would receive BID tapes.

GIB seat/Spar ready to glass

I then mixed up some epoxy, micro & flox.  I micro’d the fresh foam surfaces and then floxed some slightly uneven glass transitions (mainly from previous BID tape layups) towards the corners.

GIB seat/spar micro'd & floxed

I then laid up three separate 2-ply BID tape segments: 2″ wide x 4″ long in each corner, and 2.25″ wide x 11.5″ long for the center piece.  Admittedly, the overlap of the center BID tape was only about 1/4″ over each of the outboard corner BID tapes, but I think that will be fine for this application.

GIB seat/CS spar junction glassed

By the time I finished peel plying this layup, the MGS epoxy with fast hardener I was using was getting very tacky.  Since the temps outside were dropping to the mid-40’s F, I went ahead and put a couple of heat lamps on the layup.  I then cleaned up, brought the wings a motorcycle back into the shop and then uploaded these pics to the site.  I then checked the layup well over an hour later and all looked good, so I took one of the heat lamps away & simply left the other one on to keep the layup above ~70° F overnight.


12 October 2016 — Although I only got about 5 hours of sleep today, strange things were afoot in the shop as I slumbered.  The last thing I did before going to bed was I checked the GIB seat & CS spar intersection layup, and it looked it great.  It was a bit chilly last night so I left a heat lamp on the layup so as not to have to turn on the heat in the garage for a layup that was essentially cured (or so I thought).

Wanting to check out my masterpiece this morning I was of course taken aback when I saw a HUGE delam bubble running down the face of it.  Wow!  The only thing I can guess is that perhaps the pour foam was still off-gassing just a tad and over the hours it created a bubble.  Or maybe I just need to stop my shenanigans of combining heat lamps with fast hardener… might be just a bit too much for these layups to handle.  I’m going to try a mini experiment with that and not use heat lamps on fast hardener layups for a while and see if there’s a difference.

GIB seat/CS spar junction layup

Ok, so here’s this hideous monstrosity of a delam . . .  Boo!  Hiss!  Argh!

GIB seat/spar layup delam!

It was a few hours before I got around to working on it, or even taking these pics and I swear it GREW!  Stand back folks, this ain’t your garden variety delam… this here is a Mojamma delam, and it requires extrication!  So I marked off the area for surgery.

GIB seat/spar delam marked

And cut it out with my Fein saw….

GIB seat/spar delam cut out

This is what a close view of sheer disgust looks like!

GIB seat/spar delam cut out

So of course I had to cover it up… with 1-ply of BID of course.  That’s after sanding it and floxing the transitions.  I also injected a couple of smaller bubbles with pure epoxy off to the left (in the pic) of this delam,..where you may note the vampire bite marks.

GIB seat/spar delam re-glassed

Later, I checked the layup on the GIB seat/CS spar.  It looked good & quite well cured, so I pulled the peel ply to get a good look.

GIB seat/spar delam repair layup

it honestly looks really good!  It may seem like it still has jagged edges and all, but as I’ve said before, that’s the blessing & curse of MGS, you can see everything.  So it may still look a bit delam’d, etc. but the new layup is fine.

GIB seat/spar delam repair layup


Back to Top

Recent Posts

Project Update

Hey Guys,

I’m happy to report that the install of all the internal CF baffles is complete, including the final gap fills around the edges to ensure minimal air leakage. 

As I’ve noted previously, all the exhaust pipes have been welded, with the required trimming of all the exhaust pipes to length coming soon.  I’ll caveat the exhaust pipe effort with the fact that I may need some welding on the ends of these pipes to get them pointed in the right direction, but I’m of course hoping not.  In addition, I have 2 compression style EGT probes from GRT on hand and will need to have the stainless steel threaded bungs welded to the exhaust pipes to mount those specific probes.

The convergence of a few intertwined components I spoke of before is STILL slowly coming to fruition, which will set me up to be nearly done with the entire engine install, sans the firewall (at this time).  With the CF inner baffles now installed, I can turn my focus on finalizing the aft lower side of the engine aluminum baffle install.  That will, in turn, allow me to identify where the bottom cowl cross rib baffle/stiffener needs to get glassed into place.

I’m still intent to focus solely on the plane for the next however long it takes to finish this bird… ASAP!  

  1. Chapter 3/22 – New backup EFIS/clock! Leave a reply
  2. Chapter 3 – Lathe CNC squawks Leave a reply
  3. Chapter 3/19/22 – Lights & Lathe Leave a reply
  4. Chapter 3/19/22 – The struggle is real! Leave a reply
  5. Chapter 3/19/22 – More Lathe Stuff Leave a reply
  6. Chapter 19/22 – Wing light brackets Leave a reply
  7. Chapter 3 – Lathe CNC spindle control Leave a reply
  8. Chapter 3 – Tooling up: Lathe CNC Leave a reply
  9. Chapter 3/23 – Dipstick cap & Lathe Leave a reply