Bou's M-19 Project

Flying edition construction

20200217- 20200225 Many project related, non-construction tasks undertaken;

20200229- Leap Day! Began assembling Construction Manual into 2 volumes;
V1=new digitized text document &
V2=original diagrams and CAD dimensions

20200305- place OC Formular 250 3/4" Square Edge order for 15 sheets with Kaz @ Service Partners/ Tigard
- RCI seat arrived today and plopped it into the mock-up cabin; looks like it might work.

20200306- build cross-reference for parts list to drawings callout
- Called John Pike of Big Sky Stearman; told him I bought spruce for my KR2S from Claude, his dad in the 1990s; sent email for quote
20200307- requested sheet steel quote from Metal Supermarkets Portland
20200308- received quote @ 161.79
20200309- called HIO FSDO re: if a plans review is recommended prior to buying materials
- requested sheet steel quote from West Coast Metals
- requested sheet steel quote from
- Keith Ruconich/ HIO FSDO called and confirmed no plans review required; work with Gary Brown again; "Good Luck!"
20200322- placed 4130 order from Josh @ ACS
20200323- added 9x9x.250-4130 to ACS order
- placed initial composite products order from ACS
20200324- created CAD drawing for #2 Rudder Pedal
20200325- submitted RFQ to Wicks for parts
20200330- Cut to fit firewall & instrument panel; laminated 2 scraps of 6.5mm plywood to form 1/2" blanks for aileron horn plates and tail plate;
laminated 2 pieces of 1/4" plywood to form 1/2" blank for spring plate
20200331- cleaned up shop; rough cut tail plate
20200401- picked up foam at Service Partners; stored in shop; now I just need wood!

20200402- CAD drawing for #9 Bottom Bellcrank and #10 Lower Aileron Pulley brackets; ordered new band saw blade
20200403- Finished #55 Aileron Horn Mount Block & #82 Tail Plate fabrication; cut nose rib pattern template
Waste not, want not. I laminated plywood "scraps" from an earlier KR2 firewall replacement remnants to make required dimensional stock.
Hand cutting to minimize the kerf let me get both horn mounts from a tiny piece of material.

Sorry about all the photos of me.
With the FAA Repairman's Certificate in mind, I must document who is actually building this airplane...

Count those plies! 

Yeah, you're right, 13mm & 20 plies...

20200404- used acetone to transfer nose rib pattern to plywood template, cool!
Pretty simple actually. Print diagrams with a laser printer. Trim to size and lay image side to material. Saturate a cotton ball/ paper towel with acetone and rub the back side of the printed image firmly onto the material. Carefully peel it off and the reverse image is transferred to your material.
--UPDATED-- I found out it is better to apply acetone with an acid brush. Ink transfer works better with a tongue depressor cut to a blunt straight edge. It "pushes the ink" onto the material.

Cut & trimmed to final shape

20200405- cut 1st XPS sheet to 40x48; blocked to 6"x10"; laid out template line, rough cut on table saw, sanded to line on disk sander, jigged with 2 wood templates and sanded to consistent size; cut 3" lightening holes on drill press; all 32 done took almost all day + 45 minutes with the shop vac. Gotta be a faster way...

Jump to Hot Wire Rib Cutting page

20200409-12 Actually got some flying in, cleaned up shop, mounted & rewired my mid-60s belt & disc sander & motor

20200413- Remade trailing ribs to higher standard

2020415-19 More CAD drawings; Thank you Neal!

20200425- picked out wood for cab structure with John Pike at Big Sky Stearman

20200426- ripped wood to dimension for cab layout. Turns out I was a few pieces short...

20200427- picked up remaining wood for cab structure at Big Sky Stearman

20200429- ripped to final dimensions

20200430- rough chop cut to individual lengths

Oscar helped me visualize how the parts come together. Thanks Oscar!

Side 1 Layup

Side 2 Layup - Door side - still not positive if it going to be on the Left or Right; thinking it's the left...

20200504- Door layup complete. I used 0.041 stainless safety wire as my spacers instead of the credit cards Marvin used.
Note oversize gusset blocks for hinge mounting and the door latch.
I haven't yet decided about the armrests Oscar installed but I think some structure adjacent to the seat would be a good idea.

Tomorrow, I get to remove the guide blocks from the table and stand up the frames. Yay, 3 dimensional project!

Cut the forward carry-through spar

Cut and fit the floor members

Start by making a straight base line for the forward fuselage point. I wrapped S4S spruce members with wax paper and clamped them into place aligned with the table end. Then place one row of guide blocks on the table surface at 90 degrees to the firewall. Next place another row of guide blocks 25 1/2" away to keep the sides parallel and properly spaced. I used wedge blocks for the flooring clamps. This is a critical step as all alignments are derived from a square and true cabin structure. Tip: Mark your spar locations now while you aren't rushed.

Now that everything is cut and dry-fit, practice your assembly sequence. There won't be time to muck about after you mix the glue.

Finally, it's go time! Erect the sides, glue up the floor members and carry-through spars. Use carpenter squares to assure the sides are square to the table and each other. I used bicycle tubes as clamps for the spar-to-side rail glue joint.

I used 2 batches of T-88 epoxy (about 100g) each to extend work time. There is a considerable amount of surface area to coat; all 60" of both 3/4" inner side frames, the adjoining longitudinal members, the ends of all the cross-members, the firewall structure members and gussets and, oh yes, the spars. A disposable chip brush helped spread the glue quickly. Go go go...

My resulting cabin build. I'm happy with this.

I'm getting to the point where I now need the metal parts. Next step is to fit the carry-through spar Wing Attach Fittings (WAF) to the cab frame.
Actually I need to install the structural screws into the wing chord "N" rails and spars. It's tight for clearance so I've switched over to practicing on my mock-up.

Jump to MetalWorking page...

Getting all the parts together to drill the carry through spars includes having the wing chord plates done; check

20200708- Catalog all my AN hardware into a storage drawer bin.

20200714- Worked in Cal's shop trimming, bending and shaping metal parts

And Cal welded my rudder pedals

20200719- Finally tried on the cabin for size; just right!

20200721- Cut through the chord rails. I was concerned about this step as an error here would be catastrophic. It turned out to be just another building step.
Since I made CAD drawings for all the metal parts, printing them as templates for layout seemed a good idea.

Transfer the cut lines and score them to avoid splintering the chord rail. Drill through.

 Connect the dots and clean up the slots. Insert the WAFs & drill the fastener holes. Done. Repeat...

20200725- Data point. 25.5# bare Doug Fir structure.

20200725- Cab floor XPS panels installed

Then my camera screwed up and I couldn't get any photos. From the 25th & 30th, I installed the remaining XPS panels into the cab frame and filled gaps between the wood & XPS panels.

20200730- I cut the XPS panels to fit the roof forward and center sections. The manual says to use a knife to cut slots almost full depth allowing the panels to conform to the upper airfoil profile. I figured I'd slip and cut all the way through the panel. I used my table saw with the blade set to 10 degrees and ran the XPS panel through. Then I reset the fence to the other side of the blade and reversed the XPS foam's direction to complete the 20 degree notch. It DID make a heck of mess as evidenced by the face of the table saw...

I made an error interpreting the drawings of the wing chord plate and set the position 1/8" too high. With 40G of T-88 epoxy, there's no removing the chord plates. I conferred with Oscar and decided to laminate a strip of spruce to the top of the wing center spar carry throughs.

20200802- Moved the cab to the hangar to get the exterior bottom skin at working height. Finished filling gaps with micro. Sanded smooth.
Cleaned and organized the shop for fibreglass work.

20200803- Skinned the exterior bottom skin with Hexcel 7725 BID 8.8 oz cloth & AeroPoxy PR2032 resin and PH3660 hardener
I followed along with what Mark Langford taught the KR builders about using a sheet of plastic (his site explains ALL!) to template the required fibreglass cloth size. Bonus is that it gives you a working surface to wet out the cloth with resin and then to move it into precisely the correct spot before fixing the final location.

Layup transferred and squeegeed into place with transfer plastic sheeting removed

Applied Peel Ply

20200806- 08 Cabin interior prep for glass; fill dents & seam gaps, rough sand & repeat; pour fillets between floor & cabin sides

20200809- finish sand cabin interior

20200810- lay out materials; too warm to use epoxy already @ 9am

20200811- Lay up cabin floor 1:34 elapsed time about 500G resin

20200813- Layup Right side cabin wall interior

20200814- Layup Left side cabin wall interior

20200815- Trim and sand glass flashing; place outdoors in 103 degree sunny day to aid (post) curing
rough located main landing gear structure, rudder pedals & seat

20200816- Get measurements for fabricating MLG & wing strut carry thru channels

20200817- Metal work on wing strut carry thru channel

20200819- Redesign WSCT to use 4130 box section tube with reinforcing bolt hole webs weldments

20201027- No excuses for time passing. Got shed shop reorganized to start up again.
                    Next steps:
                    Drill the cabin area for rudder pedals, MLG brackets & strut attachments for MLG & wing struts
                    Install the firewall, forward deck foam, instrument panel & roof foam. Then glass the exterior.

This is my helper making sure the firewall plywood doesn't slip on the work bench. Thanks pal, now move so I can get something done...

T88 mixed with micro-glass fibres (to increase bonding ability) into a slurry. This resists running off the surface prior to making the wet connection to the fuselage cross & vertical members.

Lay out the cabin structural gussets.

Then install the carry through steel tubes. Reminder: the channels were bent without a proper 1/8" radius allowance. And they cracked...
So we redesigned these to use 1"x1"x.065" 4130 steel tube with 1"x.065" 4130 steel doubler plates welded on, giving both sides the 1/8" thick bolt bearing surface to carry the loads.

Even though I used LibreCAD to lay out the placement, I didn't see this coming.

So I'll get to remake the WSCT tube enough longer to clearance the bolt heads. Yeah, ok, I'm still a novice builder...

Part of the M-19 design is foldable wings so these bolts have to be removable. Best practice says bolt heads should always be forward. This doesn't always work out as practical. Case in point: engine mount bolts; these run through the firewall and to install cotter pins or even check that they are still present, you have to be able to see them. That's only practical under the engine cowl so those bolts have to run with the nuts on the forward side. And even Cessna does it this way...

Finally everything is in place (with the disclaimer I get to remake the tube referenced just above...)
*The tube on the left is the WSCT and has 2 AN3 heads exposed to anchor the cabin structural gussets.
*The tube on the right is the MLG forward pivot mount and has 4 AN3 heads exposed to anchor the rudder pedals.

With the floor holes now drilled and fitted, it's on to finishing the cabin with getting the cowl deck, instrument panel blank and roof panels into place in preparation for the exterior fiberglass.

Getting ready to hinge the door with these;

The Square is in place to help visualize the hinge pin alignments. Oscar pointed out if the hinges are aligned with the frame, the door will swing up and into the wing. No bueno. So the hinge pins have to be vertical & the upper hinge must be offset forward. Hmmn, funny, just like Marvin drew it in the plans on Page 64 of the Draeings book . Duuh. Thank you Marvin.

If I'd just pick up on all these fine details without bugging OZ maybe he'd be flying by now...