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

[Andy Hoffer]

Oops. Goofed again.

My knife slipped and crushed a stringer.  (Photo 3331)

Now we come to the next section of our build class.... How to repair a broken stringer.

Problem: this is a bowed fuselage.  If you cut out the broken stringer and replace it, you will get a flat repaired section on a curved surface.

Step 1- cut out the broken stringer at the formers.  Make the cuts on an opposing angle (45-ish degrees).
Step 2- get a wider scrap of wood the same thickness and cut an angle on both ends.  If one angle is correct, sand the other angle until the angle matches and the length matches. The repair piece is at the tip of the knife (#11 blade) in photo 3332.   Let the extra thickness stick up above the fuse as shown in photo 3333 (the top stringer in the photo).  Glue in place.  Yes, I removed the excess glue after I took the picture.
Step 3- when the glue is dry, sand the contour into the top of the repaired stringer.

Now back to our regularly scheduled program. 

Frank

Textbook repair.  Nice job @Frank v B .

Andy

[Frank v B]

Andy,

re: your question: "Could you talk a bit about this polishing procedure".

When I mixed micro balloons with 5 minute epoxy I noticed about a 1 minute rubbery phase after it has mostly set. Rubbing it with water seemed to burnish it and it actually takes on a sheen.  The water acts as a lubricant.  My guess is that the effect would be even better with a fine wet rag.
It still has to be sanded because the covering will probably not stick to this shiny epoxy.

F.

[Andy Hoffer]

Andy,

re: your question: "Could you talk a bit about this polishing procedure".

When I mixed micro balloons with 5 minute epoxy I noticed about a 1 minute rubbery phase after it has mostly set. Rubbing it with water seemed to burnish it and it actually takes on a sheen.  The water acts as a lubricant.  My guess is that the effect would be even better with a fine wet rag.
It still has to be sanded because the covering will probably not stick to this shiny epoxy.

F.

Thanks @Frank v B .  What about using rubbing alcohol (no pun intended! honest!!), which is used for removing uncured epoxy from tools and aircraft surfaces.  This would leave a smooth finish.

Andy

[Frank v B]

The build is progressing:

- made the nosecone/cockpit/hatch assembly.  Installed a magnet as a hold-down.  This will either be the battery hatch if the battery has to move forward for balance or the hatch to make the battery connection if the battery is buried further aft.  Leaving my options open.  It is drying now.
- built the second nacelle and installed the motor and electronics
- installed both landing gear legs.
- finished some stuff on the wings like hard points around the servos and ESC wires so the covering can stick.
- picked up the props from Guy "Spitfire" O'Reilly.  His Spit looks terrific.

photo 3340 - the front cone insert with the magnet in place.  The edges have been sanded so they slide into the nose cone and increase the gluing surface.
photo 3343 - the back of the cockpit glued to the cockpit floor.  This assembly  (cockpit back, floor and nose cone) is one piece held with one magnet6 (so far).

Note in photo 3340 the masking tape around the whole fuse just behind the cockpit back wall.  When I went to open up the former a bit just in case the battery needed some room the former split open.  There was so much outward tension in the stringers that it pulled open.  It was the only former that I had not braced top and bottom with a cross brace.  Live and learn.

Frank

[Frank v B]

- The removable cockpit/nose cone all done and dried.  Photo 3354
- Built the ailerons.  The inside half of the ailerons are quite thick.  Had to glue 3/32 balsa to make it thicker.  Since I used a water based glue on two pieces of balsa of different thicknesses I clamped them to a metal ruler to keep them straight as they dried over night.  Photo 3347
- made the tail wheel.  Decided to make a castoring* tailwheel.  That requires the post and tiller arm to be on a backward angle.  Drilled and glued a piece of aluminum tubing in place and inserted the wire. Photo 3349

Frank

* freewheeling- no connection to the rudder or servo.  To make it work, the post (tube) has to be on angle.

[Andy Hoffer]

- The removable cockpit/nose cone all done and dried.  Photo 3354
- Built the ailerons.  The inside half of the ailerons are quite thick.  Had to glue 3/32 balsa to make it thicker.  Since I used a water based glue on two pieces of balsa of different thicknesses I clamped them to a metal ruler to keep them straight as they dried over night.  Photo 3347
- made the tail wheel.  Decided to make a castoring* tailwheel.  That requires the post and tiller arm to be on a backward angle.  Drilled and glued a piece of aluminum tubing in place and inserted the wire. Photo 3349

Frank

* freewheeling- no connection to the rudder or servo.  To make it work, the post (tube) has to be on angle.

Holy mackerel @Frank v B !  (I mean, "Holy Macro Frank!") What a great thought-provoking post! 

And I love the evocative perspective of your feet on the floor in Photo 3349!

Ever your attentive student.

Andy

[Michael]

Nice building. It's starting to look like a DC3.

[Frank v B]

Spurred on by Michael's  "It is starting to look like a DC-3" I pushed to get the stuff together. 

The cowls, nacelles, ailerons, hinging the stabilizer, cutting and hinging the fin/rudder and ailerons, installing the wheels.  The main LG is a little long but I have not put the props on yet.  Will decide based on the ground clearance.

Now it is really starting to look like a DC-3

Frank

ps re: Andy's "the perspective of your feet on the floor".... Size 13's... I can't coil them up!  Also, photo 3360 is just for you.  It is perfectly in focus.  If it looks blurred then you had too much wine with dinner.

[GuyOReilly]

Love it, it looks great!
My wife's all time favourite aircraft too.

[Andy Hoffer]

Spurred on by Michael's  "It is starting to look like a DC-3" I pushed to get the stuff together. 

The cowls, nacelles, ailerons, hinging the stabilizer, cutting and hinging the fin/rudder and ailerons, installing the wheels.  The main LG is a little long but I have not put the props on yet.  Will decide based on the ground clearance.

Now it is really starting to look like a DC-3

Frank

ps re: Andy's "the perspective of your feet on the floor".... Size 13's... I can't coil them up!  Also, photo 3360 is just for you.  It is perfectly in focus.  If it looks blurred then you had too much wine with dinner.

Hey @Frank v B ,
Time for a tripod and self-timer. 
Andy

[Frank v B]

Andy,

re: "Time for a tripod and self-timer.  Andy"

Got them, thanks.  See photo of my tripod and timer (watch).

Frank

[Frank v B]

How to make the in-fill balsa triangles between the stab and fin.

The one supplied in the kit are plastic and are shaped for a much thicker stabilizer and fin/rudder.  I made the tail feathers out of 1/4" balsa and essentially flat with rounded edges.  Photo 3361 shows the gap that needs to be filled.

Step 1- remove the tail feathers and sand everything smooth and square (edges, cut overhanging stringers, etc).
Step 2- build up the space the elevator and the fin would take up.  Normally I would have made that "T"-shaped insert out of sheet balsa but made it out of 1/4" sticks this time. I glued each piece of wood with two small dots of carpenters glue where it meets the fuselage.  Photo 3362 and 3363.
step 3- cut blocks of balsa or triangle stock to fill each side of the space.  This space was quite large so I used a block from my scrap drawer. Photo 3364 shows the blocks rough-cut to size with a band saw.
step 4- spot-glue the blocks in place. Photo 3366.  Photo 3367 shows some masking tape on the fuse structure to protect it from accidental sanding.
step 5- I used a knife to round-shape it, then a razor plane, then a sanding block.  Elapsed time 10 minutes.  Photo 3369
Step 6- cut through the glue spots to remove the balsa.  The shaped fillets are shown in photo 3370.

The stars of the show shown in photo 3372-  The pieces of shaped wood, the knife, the razor plane and the sanding block.

Frank

ps: the green masking tape on the knife?  To stop it from rolling away.

[Andy Hoffer]

Andy,

re: "Time for a tripod and self-timer.  Andy"

Got them, thanks.  See photo of my tripod and timer (watch).
Frank

@frank this is an excellent first attempt.  You might want to straighten the legs on the tripod, and remember that YOU are responsible for EVERYTHING in the frame.  The timer will not jump into the image on its own. YOU have to frame the photo so that BOTH the tripod and ALL of the timer are clearly visible.  Granted, your present intellectual and informed audience can infer the presence of a timer, but from what is depicted that may be overstating the capabilities of the device shown.  For all a viewer knows it could be nothing more than an analog watch, with no sweep second hand to allow sufficient exposure precision, nor Bluetooth shutter release for the camera.  While one can rightly argue that the minute hand, and, on a longer time scale, the hour hand, are indeed timers, my modest experience in this area suggest that you probably need no more than 1/4 to 1/2 second exposure to allow a very small aperture (at a suitably low ISO to minimize image granularity) to give you the depth of focus you are so valiantly seeking. 

Always trying to be helpful,

Andy

[Frank v B]

Covering

Rifling through my two boxes of about a total of 30 rolls of covering I have decided on the same colour scheme as Michael's awesome DC-3*. 
Michael's plane will have its own mini-me.
Sorry Guy.  Buffalo Joe will not be flying around TEMAC.

Part of the reason:  Three colours are required (red, white, silver).  I had all 3 in Solarfilm and the matching silver in spray paint for the plastic parts.  Solar film is best for small planes for three main reasons.  It is the lightest of the regular plastic coverings like OraCover or Monokote, it requires the lowest heat to apply and has significantly more shrink than Monokote.

The problem with using different makes of covering is that you cannot put a high heat covering (Monokote) over top of low heat covering (SolarFilm) at the colour transitions.

Frank

* Did you know Michael's DC-3 build thread has had over 52,000 views.  Wow!

[Andy Hoffer]

Hi @Frank v B

Good note on different types of covering.  How does the adhesion of Solarfilm compare to Monokote and Ultracote?

Thanks, oh sagely one. 

Andy