IMAC Pattern - Cadence w/ DA 35

[dhal22]

Bart:

No change in size for the DA 35. Has a 77" wing span - shooting for 10# dry. For comparison, my piedmont 2m focus had a 74" ws and was 78" long with a YS 140 sport (23cc). Thought it was underpowered as it would slow down on uplines. The Focus weighed in at 10lbs-3oz dry.

What I am learning is the newer style 2m pattern planes continue to create more inherent drag requiring more hp (slower flights). This is in contrast to the old days of .60 size piped with retracts.

Wheels up and on the pipe...................

 

[Alky6]

Wheels up and on the pipe...................

Oh yeah!

 

[Alky6]

New fuse sides have been cut (reduced them 1.5”). In the pics is a building board with slots to allow the formers to extend past the sides. The fuse is constructed with the top down, so cutting off 1.5” presented some challenges to how to construct. Also, made some jigs to hold the fuse sides and set the right thrust on the firewall.

 

[TonyHallo]

What do you use to glue together?

 

[Alky6]

What do you use to glue together?

Requires (for good adhesion to the prepreg panels) Hysol 9412. Can use any epoxy made up to mashed potatoes consistency with cabosil to fill ends. But anytime a good bond strength is necessary the Hysol is necessary along with a little tape or cut cloth. I prefer cutting cloth as you aren’t left with a seam where the tape is woven together that is unsightly. It’s measured by weight for mixing.

The pic below is an old can.

 

[dhal22]

A gallon of Hysol?

 

[Alky6]

A gallon of Hysol?

Ha ! Yes a gallon! That gallon is left over from the days of building full scale race boats. Not much left. Will probably use 9430, comes in quart size can. I would have to split the 9412 with a buddy that is still building the boats. A gallon wil last a long time!

 

[TonyHallo]

I will be looking forward to this.

 

[Alky6]

More prep work done. Did a glue trial as I am concerned the weight gain will be significant if I use epoxy mashed potatoes to fill the edges of the panels where the aramid honeycomb is exposed. Specifically when gluing to wood. Used Poly glue with great success. Material (light ply) broke before glue joint. Very poor adhesion to the prepreg carbon as expected (see last pic).

Firewall prep:- engine mounting holes drilled oversize and filled with epoxy mashed potatoes. Needed as the honeycomb is terrible in compression. Holes drilled for a DA 35. I am using some e-glass 3/8” material for the firewall. Very stiff as the skin is much thicker than the carbon, but will take some abuse. Still need to open up the hole a bit more to save some weight and leave room for the throttle linkage.

Relieved 1/8” of top of tail to glue in 1/8” lite ply to support the balsa tail. See pic below, routed such that outer skin is still intact and portion of honeycomb left to give poly glue something to bite.

Holes drilled for wing tube and adjusters. Need to slot for adjusters still.

LIghtened the intermediate former (at the break to start the taper on the fuse).

Test portion where lite ply broke before glue joint using poly. For a good structural bond, hysol is still a necessity.

 

[49dimes]

This build has me really intrigued to the methods and materials used in construction. Looking forward to your continued progress Paul.