Bou's M-19 Project

This is an addition to all the great information at Oscar Zuniga's site

I'm currently flying a KR2S and that covers the "fast & inexpensive" aspect of VW-powered wood & composite aviation.
My buddy Steve has T'Craft and we have a goal to explore all the Oregon state airports. Some of them are definitely NOT "KR-friendly" due to short length or rough conditions.
Enter the "slow & inexpensive" aspect of VW-powered wood & composite aviation. Here is where the Flying Squirrel comes into the plan.

I visited Oscar in 1999 and looked at his project in progress. I was interested due to it being the same construction techniques and powerplant as the KR family. It was fun to see and didn't fit into what I saw as my goal for going fast. It still doesn't but 20 years later my goal changed...

Fast forward and I visited Oscar 2020-01-26. His project is much further along and it isn't flying yet. I think his Pietenpol may be distracting him too much!
Well that and getting ready for retirement; he's working too much right now.

I got a few detail photos of Oscar's project of areas that troubled me on the KR builds I've done in the past.

20200201- ongoing development of CAD drawings for all metal parts to allow water jet cutouts
- Today I bought some 1x furring strips at Home Depot to mock up a cabin. I'll need to make room in my shed first...

20200202- Cleared the KR2S from the shed, cleaned up some room

20200203- Bought material for new building table

20200204- Built table

20200205- Cut first wood for cabin mock-up

20200206- Dimensioned all the furring strips; rough-cut cabin side pieces to length

20200207- Ran through 2 1/2" increase in cabin height calculations; got a sanity check from Oscar
                    Fit fuselage side pieces to fit jig board

20200208- Finish fit all fuselage side pieces; glued up with T88 epoxy
(The cabin did increase in height and this photo is distorted because it doesn't actually look like this!)

20200209- Lifted Side 1 off the work surface this morning.

Finish cut & fit pieces for Side 2; laid it up with T88 epoxy.

 20200210- Remove Side 2 from the frames; erect both frames in rough position, rough cut floor pieces, dimension both spar carry-throughs

20200211- Finish trim all floor sections; square off fuselage profile sections to table, glue-up floor
I used Titebond-II glue; it has a short open time and partially set up before I finished. Ok, it is just a mock-up.

20200212- Removed clamps, drove staples through bottom longeron into floor sections; Woody is where the seat goes.

Holy Moly, this thing is huge! This shows setting the datum position as Marvin did; prop hub=0"

So the seat is now at Marvin's 60" aft of datum position or 41" aft of the firewall

This is how much legroom I have! I'm 6'1" with a 32" trouser in-seam.

My toes are fully pointed out forward! There is no way I can come close to touching the firewall.
Sure there are rudder pedals yet to be installed, even so...

--LATER THIS AFTERNOON-- I moved the seat back about 3" and sitting upon the 6" high seat platform, it needs to be lower.

Seated on the platform in profile view so note legroom

I expect a lower seat platform will give my desired headroom improvement from the 2.5" height increase

20200213- I want to be able to try out the entire build before I start for real & I'm ok with doing it twice.
Today I skinned the exterior cab frame for rigidity and to enclose the structure. This makes everything "real."

A dummy firewall would give the entire structure more shear strength but it will just be in the way...

20200214- Trimmed the boat skin overhang; printed, trimmed and connected wing chord patterns
Cut out chord plates and positioned on cab "N" rail, so called "chord beam"
Position of seat is approximately 60" arm of his "prop hub datum")
Marked 25% - 33% MAC (pink lines on airfoil template) string approximates Marvin's W&B CG @ 52.06"
If my measurements are good, the M-19 with his pilot 208# & full 8G fuel was in the FAA "sweet spot" CG!

20200215- I cleaned the shop, dummied up an alternate control stick, trialed an idea for movable seat and rudder pedals, and put some Tung oil on the plywood. Just because. Nothing is photo worthy. Perhaps tomorrow...

20200216- installed dummy rudder pedals and full control loop cabling to confirm seat placement location

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

20200226- Framed and glued the cabin mockup door.

20200227- Today I installed a piano hinge onto the mock-up. Not sure why the plans call for modifying a set of cabinet hinges.
Oscar told me that the hinge pin has to be perpendicular to the floor or the door will scrape the wing bottom skin. Oh...
Cut a panel of Corning Formular 1" Pink XPS to fit the lower door section and  glassed it in place with AeroPoxy & KR Cloth.
This will permit sanding test if unable to procure 3/4" thick foam material. Will confirm adhesion with a tear-test next
Also met with a machine shop owner to review drawings' suitability for water-jet cutting metal parts

20200228- Trimmed layup in green stage. Appears to be good adhesion to the Owens Corning Formular test panel. The AeroPoxy is stale and resulting in a slightly sticky cured state.

20200229- Leap Day! Began assembling Construction Manual into 2 volumes;
V1=new digitized text document &
V2=original diagrams and CAD dimensions
Ran the test sanding trial on the bonded 1" Formular panel in the mock-up door. Stiff.
Resorted to 36 grit followed by 80 grit resulted in substantial effort, even for this small panel.
Click the image for hi-res photo. 80 grit gives good tooth for the resin/ micro sealing layer prior to glass layup.
Prospective builders should run this test. There are many XPS panels that need to be reduced to 3/4" thick framing members.
As an alternate, a neighbour suggested using a hot wire to trim 1/4" from 1" thick XPS material. May be worth a try. As would cutting 1 1/2" in half...

20200305- place OC Formular 250 3/4" Square Edge order for 15 sheets with Kaz @ Service Partners/ Tigard
- RCI seat arrived today; 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 from Claude, his dad; sent email for quote

20200307- requested sheet steel quote from Metal Supermarkets Portland
Please quote:
Will call pick up.

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 WestCoastMetals
- requested sheet steel quote from
- Keith Ruconich/ HIO FSDO called; no plans review required; work with Gary Brown again; "Good Luck!"

20200312- sent reminder email to John Pike

20200319- sent reminder email to John Pike
- escalated 6x36x.125-4130 order from ACS

20200320- called John Pike back; he will have a price quote Monday or Tuesday

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

20200326- called John Pike; his resaw & grader guy is older and is staying home right now; the shop is still running with greatly reduced staff
- checked foam order with Eric at Service Partners; first 1/2" was sent; researching when the 3/4" will arrive & WCB

20200330- Cut to fit firewall & instrument panel; laminated 6.5mm to form 1/2" blanks for aileron horn plates and tail plate; laminated 1/4" to form 1/4" blank for spring plate

20200331- cleaned up shop; rough cut tail plate; 59 1/2" band saw blades available at HD 3 assorted at $20

20200401- picked up foam at Service Partners; stored in shop; now I just need wood! Plus you might notice an RCI Low Back Poly Race Seat in place...

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.

Count those plies! 

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

20200404- used acetone to transfer nose rib pattern to plywood template, cool! Cut & trimmed to final shape

20200405- cut 1st XPS sheet to 40x48; blocked to 6"x10"; layed 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...

20200406- spend way too long web-reading about hot wire to cut XPS foam; decide to just whack something together & try it; Hmmn, .020 SS wire, check; expired transponder battery, check; 1/4" 36" long dowel, check; alligator clip electrical test leads, check; masking tape, of course; 1st pass with clips on the wire about 15" apart, cut 2 @ 1" XPS foam blanks, check! Moron in the shop, or maybe not, check...

These views show the templates on both sides of the target XPS foam as well as the upcoming cut depth.

Cut in progress...

Resulting first cut shows some wavers and skippers...

A follow-on pass removed the worst of the "lumps" I missed following the template accurately.

The tiny irregularities seen above sand away with less than 4 strokes of a sanding block with 80 grit; it opens the XPS foam pores too (should give better epoxy penetration.)
With a few more cuts I'll figure out the speed for the cutting pass. I may even look to replace the battery with a constant DC power source.

For me, the bottom line comes down to having an accurate cutting profile template. THAT'S where I'm going to spend my time to ensure the rib center & trailing edge templates are also "nuts-on" to the air foil pattern templates that Marvin put in the manual. Rock on.

20200407- Time to get on to the center & trailing rib templates so to get through this stack of raw XPS blocks...

Finished pairs of center & trailing rib pattern templates for hotwiring parts;

Tools for fine-tuning the templates to match Marvin's patterns

Just a whisper of the top airfoil guide line remains

Using the corner of my table to jig up a rack to hold the templates on both sides of the raw XPS blocks

About 90 seconds from connecting the power to the hot-wire bow to completing the cut. A touch with 80 grit paper again and 6 more ribs are ready for the hole saw.

It's beautiful thing; 24 identical ribs. I knocked out the trailing rib sections today too. It was a good day!