Building the Guillow's DC-3 (35.5" span, now 38") with RC /BL motor conversion

[Frank v B]

All the pieces in the rough.



F.

[GuyOReilly]

Next Problem Challenge:
This was designed as a static model.  The wing saddle is a center rib (keel).  Then extruded plastic fillets are glued on to create the contoured wing saddle.  Three problems: 1) no strength 2) no way to give my grubby paws access to the radio/servos in the fuse. The formers are in the way, and 3) no wing attachment stuff to make the wing removable.

May I suggest 1/16 sheeting between the stringers to add a bit of strength.
The plastic fillet could still be used, and glued only to the fuse... but your hamster already figured that one out...
Guy

[Andy Hoffer]

All the pieces in the rough.



F.

Wow!  Photo 3299 by Yousuf Van Beurden.  With a scoop backdrop no less.   This guy is SO ready for Studio Lighting 101 and Aircraft Portraiture 102 !! 

Nice composition @Frank v B !!  I think you're done.  No need to do any further assembly!!

Andy

[Frank v B]

re: Andy's "No need to do any further assembly!!"


In my books that called giving up.  A model can only be a static model after it has been flown. 
It's like building a boat that doesn't float.  Imagine if Noah built the Ark as a static model.

...but thanks for something that started to sound like a bit of a compliment.

F.

[Frank v B]

Hamster Wheel Report

- retrieved the keel that was in the center of the fuse and removed all the pieces of the old formers.  Sanded it smooth.  It had the perfect shape of the top of the wing.
- Attached it to a piece of paper with Scotch tape.  Photo 3302
- held it in place and sketched the outline of the stringers onto the paper and cut two samples out of 1/16" balsa (Thx Guy).  See photo 3304
- they fit perfectly so I glued both pieces in place and will let dry. Photo 3305

Approach
- The 1/16" sides are glued in place.  When dry, I will add 3/32 balsa sides inside them to build up strength (all stringers are 3/32 so they will match).
- sand the outside to the proper contour which probably means most of the 1/16" patterns in the first step will be lost.
- re-attach the wing and slip 1/64" ply between the top of the wing and the saddle in the fuse.
- fill the gusset either with balsa or micro balloons (to be decided).

Guy, the consensus of the Hamster Wheel report was to do the fillet not using the plastic one supplied in the kit.
F.

[GuyOReilly]

Great Hamster solution! 
Love the use of the centre a a template, although one could have traced the part from the plan... 

[Andy Hoffer]

Hamster Wheel Report

- retrieved the keel that was in the center of the fuse and removed all the pieces of the old formers.  Sanded it smooth.  It had the perfect shape of the top of the wing.
- Attached it to a piece of paper with Scotch tape.  Photo 3302
- held it in place and sketched the outline of the stringers onto the paper and cut two samples out of 1/16" balsa (Thx Guy).  See photo 3304
- they fit perfectly so I glued both pieces in place and will let dry. Photo 3305

Approach
- The 1/16" sides are glued in place.  When dry, I will add 3/32 balsa sides inside them to build up strength (all stringers are 3/32 so they will match).
- sand the outside to the proper contour which probably means most of the 1/16" patterns in the first step will be lost.
- re-attach the wing and slip 1/64" ply between the top of the wing and the saddle in the fuse.
- fill the gusset either with balsa or micro balloons (to be decided).

Guy, the consensus of the Hamster Wheel report was to do the fillet not using the plastic one supplied in the kit.
F.

Anybody remember Rube Goldberg?!!!

Andy

[Frank v B]

What next:

No matter what I wanted to do next (motors, servos, wing hold-down, aileron servos, esc) it was best done after joining the 3 wing sections.

Done!..and let cure overnight.


F.

[GuyOReilly]

Yeah, better put that on ice for awhile.
So looking forward to seeing it fly!

[Andy Hoffer]

Very cool! 

[Frank v B]

Final measurement:

Plane's design- 35.5"
as built         -  38.0"

The extra inch in the center section for prop clearance, the added inboard stretch and the tip stretch added up to a 7% increase in span.  Add to that the extra wing area benefit by moving the trailing edge back 3/8". 

Frank

[Frank v B]

Wing wigglers.

Those of you who have read my build/repair posts before know that I first build/repair  the model correctly (true, straight, etc.) and then later add the strength.  Same here.  I am adding all required elements first (aileron servos, ESCs, motors, landing gear) on one side.  If everything seems OK., I copy all the elements onto the second side then I go around and strengthen all joints, holes and mistakes.

The first assignment is the aileron servo.  I rejected cables (sloppy) and torque rods (difficult to fit into a small, thin wing). 

The first set of matched servos did not fit (GWS Nano).  Opted for the really tiny Bluebird 303.  How tiny are they... see photo of two servos next to a quarter.  They are good servos but they have one nasty habit.  The cases are not screwed together.  They are friction fit and come apart.  That's why the dental floss and one drop of CA.  Standard practice.

More than enough space in the wing (see photo).  Will have the full servo horn exposed for easy adjustment.

The motor and esc are next.

Frank

[Andy Hoffer]

Wing wigglers.

Those of you who have read my build/repair posts before know that I first build/repair  the model correctly (true, straight, etc.) and then later add the strength.  Same here.  I am adding all required elements first (aileron servos, ESCs, motors, landing gear) on one side.  If everything seems OK., I copy all the elements onto the second side then I go around and strengthen all joints, holes and mistakes.

The first assignment is the aileron servo.  I rejected cables (sloppy) and torque rods (difficult to fit into a small, thin wing). 

The first set of matched servos did not fit (GWS Nano).  Opted for the really tiny Bluebird 303.  How tiny are they... see photo of two servos next to a quarter.  They are good servos but they have one nasty habit.  The cases are not screwed together.  They are friction fit and come apart.  That's why the dental floss and one drop of CA.  Standard practice.

More than enough space in the wing (see photo).  Will have the full servo horn exposed for easy adjustment.

The motor and esc are next.

Frank

Hi @Frank v B ,

Elegant technique.  I take it the servo on the left "wiggles" more than the one on the right, hence the need for a whole spool of dental floss to bind the left one versus just a couple of loops on the right one!   

Andy

Andy

[Frank v B]

The bones are coming together.

Photo 3312- the motor inside the nacelle and glued onto the wing, the aileron servo glued into the wing, the ESC will stay on top of the wing inside the fuse.  The hole in the front nacelle former was drawn around a Toonie.
Photo 3313- Only working on the starboard wing. 
Photo 3314 - The photo shows how much I moved the nacelle outboard.  The nacelle is designed to be in the middle of the two ribs.  The prop clearance is now about 7".  More than enough since a 6" prop is the maximum on 3 cells. 
Also note:
- the out-thrust in the motor.  About 2 degrees (never measured it.  It's "just enough").   Andy will probably calculate it to 10 decimal places.
- the dental floss and drop of glue on the servo extension where it joins the servo lead.  To make sure it does not disconnect.
- the yellow on the trailing edge dihedral joint.  It is 5 minute epoxy with fibreglass cloth for strength.  All 4 joints were treated that way (two leading edges, 2 trailing edges)
- the notch in the trailing edge in the middle.  That is how much I shifted the trailing edge backwards to increase the wing area (reduce wing loading).
Photo 3315- The servo tray is hard 3/32 balsa.  Its main purpose is the act as a cross-brace since I cut the bottom out of two of the formers.  The servos are Hitec HS55's.

Frank

[GuyOReilly]

@Frank v B please let me know if you would like to have these 2 propellers for your DC3.
No painting required.