Next Project is the Guillow's DC-3. Bought the kit at the London Swap meet two years ago for $20.00.
The DC-3 (35.5" span) is much larger than the B-25 (26.5" span) so the motors will be E-Flite 280's versus the 180's in the B-25. A 280 is rated at 100 watts. The 180 is 30 watts.
The other changes will include:
- removable one piece wing using a nylon bolt.
- no retracts (sorry Guy). Just fixed landing gears.
- increase the wing area two ways: increase the span about two inches and increase the chord outboard of the nacelles. The wingtips, as designed, are quite narrow. I am doing this not so much to reduce the wing loading but to reduce the twitchiness of a small plane.
- increase the area of the tail feathers a bit (10%) to increase controllability and stability.
This plane was designed as a static model. It was never designed to fly. This is why the caution on the design elements.
Frank
You might want to cheat a bit, and move the nacelles slightly out, in order to make room to swing propellers.
Perhaps consider the additional scale effect of 3-blade propellers.
There should be enough power to compensate for them being slightly less efficient.
Let me know if you need counter rotating props, I can spare 2, and they are 6-inch diameter.
Also, they are black...
Thanks for the advice Michael. I will check the prop diameter range for this motor and look at the full size plans.
Guy, thanks for the prop offer. To paraphrase Henry Ford's quote "You can have any prop colour as long as it is black".
Michael, I am seriously considering using the same colour pattern as your DC-3. It could be your personal Mini-Me. :)
Now Guy is yelling in the background "Buffalo Airways" colours!
Frank
Starting the build
- finished the formers. Cut out all the stringer and keel notches. They are piled in the top right-hand corner of the green cutting mat.
- glued the center keel parts together. Will let the joints dry overnight.
F.
Quote from: Frank v B on January 09, 2021, 10:53:33 PM
Starting the build
- finished the formers. Cut out all the stringer and keel notches. They are piled in the top right-hand corner of the green cutting mat.
- glued the center keel parts together. Will let the joints dry overnight.
F.
It's amazing what
@Frank v B can do with a knife and fork!! ;D
Andy
Starting the fuselage.
One half of the fuselage is built flat on the board, then two main keels (top and bottom) are glued in place to keep everything straight. Then it is removed from the board and the other half of the formers are glued onto the second half to make the round fuselage. Same as the B-25 and it makes a straight fuselage.
F.
Arghhh! Cutting out the stringer notches in the second set of formers. Several of the pieces broke and will have to be glued together.
With a new knife blade too. :-[
F.
That is what I call Karma...
Guy
Quote from: Frank v B on January 10, 2021, 06:36:09 PM
Arghhh! Cutting out the stringer notches in the second set of formers. Several of the pieces broke and will have to be glued together.
With a new knife blade too. :-[
F.
The formers for the starboard side.
The formers have to be butt-glued so I added glue tabs (photo 3263). They lined up the formers when clamped (3264). It allowed me to use wood glue for the main joint and CA for the small sticks to act as pins while the wood glue dries.
The finished front half (photo 3265) and back half (photo 3266).
The small stringers are next.
Frank
Sticks, sticks and more sticks.
The fuselage is very round and taking shape.
F.
Picked up the two matching ESCs today at John's Hobbies. 10 amp 2-4S house brand from Horizon Hobbies for $20.00 each, new in package. Great deal. I already have the two motors (E-Flite 280's).
Now that there is a "stay-at-home" order, I will treat it as a "build-at-home" order. ;D ;D ;D
Frank
Dear Cynthia,
I'm not quite sure how to break this to you. But there's this new government COVID-19 order, y'see? And
@Frank v B is our CFI so he takes this stuff seriously in order to set a good example for the rest of us. So you're going to be seeing a
LOT more of Frank than you normally would. I mean in the sense of him being around the house a
LOT. If you can just steer clear of the basement, you should be fine.
Call me if you need help on this. 8)
Cheers!
Andy
Stabilizer
Problem 1: the stab was made up of many small pieces and was to be aerodynamically shaped per the real one. As designed it is very thick, labour intensive and not very strong.
Solution: The new design is flat, strong and simple. Less than half the number of pieces.
Problem 2: this is a static scale plane and was not designed to fly. To make it flyable, the tail feather area should be increased by about 15% for stability and directional control.
Solution: The leading edge was moved forward about 3/8 " and each tip was moved out about 3/4". You can see the LE balsa was moved forward versus the shaded leading edge on the plan. The trimming will be done after the fuselage is finished to make it fit in the stab slot of the fuselage.
Let dry overnight.
Frank
Elegant solution Frank, I love it. Just as a matter of interest, have you calculated the new area vs the original? Is it 15% bigger?
Simon,
Thanks
re: your question "..have you calculated the new area vs the original? Is it 15% bigger?"
No, I have not calculated it. That would require math. ;) The only logic I used was to add chord to dampen pitch and to add span to dampen roll. The rest is TLAR ("That looks about right").
I don't know if it is 15%. It is "just enough". ;) It still needs to be scale and not look awkward. I can only judge that when I can pin it to the tail end of the fuse and look at it from all sides. That's why I have not sanded it yet. I have built in significant options that can be adjusted with sandpaper.
The personal guideline I use is that when two options present themselves, I lean to the corrective one. Err to right thrust, err to down thrust, err to wash-out. On small planes (less than 36" span) add to span, add to wing area nearer the tips, err to larger rudder with greater throws, err to more power, smaller prop (reduce torque on take-off), nose heavy, more elevator area, less elevator throw, more aileron throw, lighter than usual landing gear wire (to absorb a bounced landing)....... and most importantly, reduce overall weight.
Each adjustment may be small but the totality of these decisions have a huge effect..... in my opinion.... but then, what do I know? 8)
Frank
Stabilizer finished for now. All the ribs are in place and the new outline pencilled in. Note the pencil notch in the front because it has to go past the front of the stabilizer saddle of the fuse.
Frank
The fin/rudder
It is made up of shaped ribs that are almost 1/2" thick at the high point (scale cross-section). Everything is butt-glued with few continuous pieces to take the loads. The leading edge of the rudder also has the corners cut off. It may be scale but it weakens the structure. Also it does not pass the 50/50 rule*. Here is the final design:
Larger area for both the fin and rudder.- did this by using wider wood and moving the leading edge forward and the top higher.
The thinner stabilizer (3/16" thick versus designed 1/2" thick) meant the bottom of the fin rudder has to go down further.
After the glue dries I will sand the fin contour to fit the curve on the top of the fuse.
Frank
* 50/50 rule of details on model planes: if you cannot see it from a distance of 50 feet and 50 km/hr, don't waste your time on it. ;D ;D
Fin/rudder
To answer Simon's question on whether the fin/rudder was 15% larger I have forwarded this photo to Andy.
He has volunteered to calculate it..... probably to 6.. if not 10 decimal places.
Frank
Starting the wing.
Changes:
1) Per Michael's suggestion: move the motor nacelles outward. The motor needs 5x5 props on 3S so I need a little extra space. Am achieving this by increasing the flat wing center section from 8" wide to 9" wide.
2) add more wing area in 3 ways i) A wider trailing edge (see photo) ii) about an inch more span for each outboard wing section, iii) reducing the taper by making the wing tip a little wider.
Photo 3284- shows the extensions glued onto the two main spars. The doubler is just angled for the photo but it will reinforce the joint. Also notice how the left-most rib is 1/2" further out versus the plans (grey area).
Photo 3285- shows the spar extensions glued in place but it has to be trimmed before the rib can be installed.
Letting it cure overnight.
Frank
Quote from: Frank v B on January 14, 2021, 09:13:05 PM
Fin/rudder
To answer Simon's question on whether the fin/rudder was 15% larger I have forwarded this photo to Andy.
He has volunteered to calculate it..... probably to 6.. if not 10 decimal places.
Frank
Good job
@Frank v B ! Your expanded version, using the Shoelace Algorithm for Calculation of Polygon Areas (https://myengineeringworld.net/2014/06/shoelace-polygon-area-excel.html), is 20% greater than the original.
Oops, sorry! I meant 20.1154204699% !! 8)
It has plenty of margin for (your) errors!
Andy
Andy,
Thank you for your computational skills. It is more than I thought and "more than enough" 8) 8)
Frank
Port wing- outboard end
The left wing has been built and drying. Had to be creative to add some area.
1) Note the root rib is to the right of the drawing by about 1/2"
2) the back end of the trailing edge is about 3/8" back of the plans
3) the tip is about 1/4" further outboard
4) add this to the 1" longer center section
That should add up to about 15.1248635235 % larger than scale....and "just enough" ;) ;)
Frank
Quote from: Frank v B on January 15, 2021, 07:02:51 PM
Port wing- outboard end
The left wing has been built and drying. Had to be creative to add some area.
1) Note the root rib is to the right of the drawing by about 1/2"
2) the back end of the trailing edge is about 3/8" back of the plans
3) the tip is about 1/4" further outboard
4) add this to the 1" longer center section
That should add up to about 15.1248635235 % larger than scale....and "just enough" ;) ;)
Frank
@Frank v B is definitely a quick study! ;D
Andy
The other wing half.
To make it easier to make all mistakes/adjustments symmetrically I left the first half on the board (bottom) while I built the second half (top). I made an asymmetrical mistake on the B-25. Not this time.
Had to match the increased span, increase chord and the adjustment to the aileron size.
Letting it dry before adding the leading edge and the small spars (stringers).
Frank
Oops
While I was processing the photo (reducing size and adding blurr for Andy) I noticed that the trailing edge at the aileron ran on an angle. At the root end you could see the line on the plans and the trailing edge ran over top of the leading edge of the aileron by about 1/4". Went back to the building table straightened it out.
Executive summary- this guy learns from his own posts. 8) 8)
F.
Yup. If @frank hadn't been distracted by the expletives encoded in the pile of pins in the top right corner of photo #3291 this never would have happened! Pity! 8)
Andy
Andy, keep deciphering.
The motor nacelle.
Put together the starboard (right) nacelle. The two changes : i) I added a bit of right thrust- approx. 2 degrees. ii) added a ring of 1/32 plywood at the motor mount between the 2 balsa rings. The clamps are holding the two balsa rings with the plywood ring in between. These clamps are terrific. Dollarama $1.25 for 10 small ones and 6 larger ones. In the gardening section in a string bag. I just cut the little nubs off the clamp faces so they do not puncture the balsa wood.
Will be finishing this nacelle completely until it is fitted, including the wing attachment method. Then build the second nacelle exactly the same way.
F.
OMG. This is amazing. I can clearly see and read everything from corner to corner in Photo #3292. We should declare this National F3* Day. I must be hallucinating. 8)
Andy
(*Fully Focused Frank)
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.
The photo shows the cut out center rib/keel and portions of the formers.
The little hamster in the hamster wheel in my head is going to be working overtime to figure this one out. ??? Time for a coffee break. ;D
F.
All the pieces in the rough.
8) ;D 8)
F.
Quote from: Frank v B on January 17, 2021, 10:42:50 AM
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
Quote from: Frank v B on January 17, 2021, 10:45:49 AM
All the pieces in the rough.
8) ;D 8)
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 !! 8)
Nice composition
@Frank v B !! I think you're done. No need to do any further assembly!!
Andy
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. ;D
...but thanks for something that started to sound like a bit of a compliment. 8)
F.
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.
Great Hamster solution! ;D
Love the use of the centre a a template, although one could have traced the part from the plan... ;)
Quote from: Frank v B on January 17, 2021, 02:10:51 PM
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
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.
Yeah, better put that on ice for awhile.
So looking forward to seeing it fly!
Very cool! 8)
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". ;D ;D
Frank
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
Quote from: Frank v B on January 18, 2021, 10:41:02 AM
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! 8)
Andy
Andy
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
@Frank v B please let me know if you would like to have these 2 propellers for your DC3.
No painting required.
Beautiful
@Frank v B (the build, I mean)! And I fully appreciate your extra effort with complete background paper coverage to banish the supporting washing machine to the dark recesses of one's imagination.
Bravo Yousuf!
Andy
Andy,
re; your "...with complete background paper coverage to banish the supporting washing machine...."
I went out to Dollarama last week to buy two sheets of white Bristol Board as background for these photos... just to keep you quiet. :)
Frank
Guy,
They are 6" props so they may fit. I'll take buy them from you. Even if it is just for the official photograph that Andy will take before the first flight.
I'll do a reading on them. The motors max out at 7 amps.
Thanks for the offer.
Frank
ps, They are counter-rotating too.
Quote from: Frank v B on January 19, 2021, 11:45:34 AM
Guy,
They are 6" props so they may fit. I'll take buy them from you. Even if it is just for the official photograph that Andy will take before the first flight.
I'll do a reading on them. The motors max out at 7 amps.
Thanks for the offer.
Frank
ps, They are counter-rotating too.
Frank;
1- They are free. Let me know when you want to pick them up or how we can proceed wit the exchange (I might not be able to get to the field this or next week.)
2- Hopefully they will fit for flight and will look great for the official photos by
@Andy Hoffer 3- The diameter is 6 inches, I measured them. I do not know the pitch.
4- One is right the other left - just make sure the prop-nut does not come loose - guess how I found out about that one...
Have a great day!
Just had to do this!!! :o
F.
May as well handle the wing saddle now. The kit supplies a plastic moulded fillet but it will be tough to glue flush with the fuse surface. This method will add a lot of strength to the fuselage sides.
I cut two matching pieces from 1/64" plywood and slipped it between the wing and the fuselage, then ran a bead of glue to secure it.
Photo 3320 shows one wing saddle in place. The wing saddle for the other side lies loose on top of the wing.
Photo 3321 shows the saddle clamped in place to seal the gap with the wing. Will let it cure overnight and then do the other side.
Thin plywood was used because it is paper thin and strong. I will add wedges on op of it and bend thin balsa to make the top (curved) surface of the fillet.
Frank
Quote from: Frank v B on January 19, 2021, 08:38:03 PM
Just had to do this!!! :o
F.
Hmm.... starting to look like ....
Andy
Andy,
The old Blohm & Voss BV 141.
My DC 2.5 will have a great left turn..... until I add the other nacelle and it becomes a DC 3. ;D
Frank
How to do a wing fillet.
This plane has a significant wing fillet. This is the curved transition from the fuselage to the wing. The other plane with a significant version is the Spitfire.
Step 1- slip a shaped piece of 1/64" plywood between the fuselage and the wing. I released the wing hold-down screw about 1 turn to create the gap, slipped it in and tightened the screw again. Ran a bead of glue on the outside to permanently glue the plywood to the fuselage. This is covered 3 posts ago (post #50).
Step 2- I glued 3 vertical triangular riblets in place. Photo 3323.
Step 3- used the orange dowel (with sandpaper glued around it) to sand a curve into the face of the 3 triangles. Photo 3325. The curved triangles show in photo 3326.
Step 4- soaked a piece of straight-grained 1/16" balsa in a wet paper towel for an hour (photo 3327) and glued it in place. Pinned and clamped it in place. Photo 3328.
Frank
Quote from: Frank v B on January 20, 2021, 08:30:38 PM
How to do a wing fillet.
This plane has a significant wing fillet. This is the curved transition from the fuselage to the wing. The other plane with a significant version is the Spitfire.
Step 1- slip a shaped piece of 1/64" plywood between the fuselage and the wing. I released the wing hold-down screw about 1 turn to create the gap, slipped it in and tightened the screw again. Ran a bead of glue on the outside to permanently glue the plywood to the fuselage. This is covered 3 posts ago (post #50).
Step 2- I glued 3 vertical triangular riblets in place. Photo 3323.
Step 3- used the orange dowel (with sandpaper glued around it) to sand a curve into the face of the 3 triangles. Photo 3325. The curved triangles show in photo 3326.
Step 4- soaked a piece of straight-grained 1/16" balsa in a wet paper towel for an hour (photo 3327) and glued it in place. Pinned and clamped it in place. Photo 3328.
Frank
Hey
@Frank v B ,
Isn't that the sound that a frog makes? Does this make your plane amphibious??! 8)
Andy
Idiotlet! ;)
Quote from: Frank v B on January 20, 2021, 08:46:27 PM
Idiotlet! ;)
Thanks
@Frank v B .
Now THAT is a compliment!! 8)
(P.S. Is that Dutch??)
Andy
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
Sanded the wing saddle and shaped the balsa to resemble the full size plane.
The white stuff is a dash of Micro-balloons mixed with a bit of epoxy to make a very light but strong filler. Just rubbed it on with a finger, then just after it set, polished it with a bit of water...and a finger. It has not been sanded yet.
The main reason for using micro-balloons was because of the compound curves in front of the high point in the wing. It tucks back in, down and around. It took only a minute to do it this way.
F.
Quote from: Frank v B on January 21, 2021, 01:59:04 PM
Sanded the wing saddle and shaped the balsa to resemble the full size plane.
The white stuff is a dash of Micro-balloons mixed with a bit of epoxy to make a very light but strong filler. Just rubbed it on with a finger, then just after it set, polished it with a bit of water...and a finger. It has not been sanded yet.
The main reason for using micro-balloons was because of the compound curves in front of the high point in the wing. It tucks back in, down and around. It took only a minute to do it this way.
F.
Hi
@Frank v B Could you talk a bit about this polishing procedure. I assume no sand paper was used if the epoxy/microballoons mix had just set? How firm was it at this point?
Tx,
Andy
Quote from: Frank v B on January 21, 2021, 11:47:35 AM
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
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.
Quote from: Frank v B on January 21, 2021, 05:28:22 PM
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
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
- 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.
Quote from: Frank v B on January 24, 2021, 10:51:07 AM
- 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! ;D
Ever your attentive student.
Andy
Nice building. It's starting to look like a DC3.
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. ;D
Love it, it looks great!
My wife's all time favourite aircraft too.
Quote from: Frank v B on January 24, 2021, 10:44:17 PM
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. ;D
Hey
@Frank v B ,
Time for a tripod and self-timer. 8)
Andy
Andy,
re: "Time for a tripod and self-timer. 8) Andy"
Got them, thanks. See photo of my tripod and timer (watch).
Frank
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.
Quote from: Frank v B on January 25, 2021, 12:07:26 PM
Andy,
re: "Time for a tripod and self-timer. 8) 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. 8)
Always trying to be helpful,
Andy
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!
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. 8)
Andy
Quote from: Frank v B on January 25, 2021, 12:46:56 PM
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.
Hey @frank,
Could yo show us the scraps and sawdust from reducing 4 cubic inches of balsa block to 1 cubic inch. This would give the viewer a much greater appreciation of how much collateral cellulose damage a master can accomplish in 10 minutes. We plebes could only wish fro such proficiency! 8)
Andy
Andy,
If you want to figure out how to shape balsa wood, just watch some documentaries on wood chucks, carpenter ants and the busy beaver. ;D ;D
DC-3 Update.
Work emergencies have gotten in the way of my covering work but it has marched on. The fuse is half covered (top half), the bottom of the wing, stabilizer and fin. The reason for jumping around is that I always cut the larger pieces first and then use the cut-offs/cast-offs to cover the smaller items.
Will post some photos tonight.
Frank
Here is a photo of some of the parts.
F.
Gee! Who would have guessed that the Canadian Armed Forces used Solarfilm, LiPos and brushless motors in their DC3's. Very scale
@Frank v B ! Fantastic job!
Andy
Really looking good!
Thanks Michael. Mini-Me DC-3 is coming along.
Some more detail work. The final assembly is next.
F.
What a beauty!!
Guy,
Thanks.
It's OK. Right now it looks like a dead fish with windows.!! ;D ;D
Frank
I do not know if you saw this documentary about the DC3. It is a bit long, but an interesting film.
https://m.youtube.com/watch?v=kvh3o4U5jnw
Quote from: Frank v B on January 31, 2021, 10:45:37 AM
Guy,
Thanks.
It's OK. Right now it looks like a dead fish with windows.!! ;D ;D
Frank
Hey
@Frank v B ,
Holy mackerel Batman! 8)
Andy
Guy, I watched the video. Amazing how long this plane has been in the air. There is a special DC-3 connection to our family.
Our family (mother, brother, sister and I) escaped from Indonesia in 1958 by piling on a hijacked DC-3 from Jakarta airport. It helped that the president of KLM in Indonesia was our neighbour. We were given 24 hours at gunpoint to get out of Indonesia when president Sukarno took independence from Holland. They came into our house with machine guns and bombed my father's company car.
Installing the tail section.
The order to get an accurate alignment:
step 1- install the wing.
step 2- install the stab/elevators so they are level with the wings
step 3- install the fin/rudder with a triangle to make sure the fin is at 90 degrees. This photo is of the fin/rudder installation. The triangle is taped in place with masking tape.
Frank
Cute as a button!
The props look a bit aggressive. The decision will be made with an ammeter.
The main landing gear stands the plane a little high but I will leave it as compression space for a hard landing. I know the pilot. :)
Still to be done- attach the servo linkages.
F.
Gorgeous!
It looks amazing!!
How about a few panel lines with a felt tip pen and a straight edge?
Really a fantastic project.
I think that 1/3 power is all you are going to need for level flight.
Thanks Michael and Guy. Much appreciated.
Guy re: your "How about a few panel lines with a felt tip pen and a straight edge?" Are you nuts!! This is a Covid project, not Covid punishment. ;) ;)
It will never be part of the 50/50 rule*.
Frank
* if you can't see it from 50' and at 50 km/hr. don't waste your time on it.
Well
@Frank v B ,
I guess it's time to ice the cake!
https://www.youtube.com/watch?v=JONkLEx6zeE
Andy
Quote from: GuyOReilly on January 31, 2021, 11:04:09 AM
I do not know if you saw this documentary about the DC3. It is a bit long, but an interesting film.
https://m.youtube.com/watch?v=kvh3o4U5jnw
Thanks so much for sharing this
@GuyOReilly . It provides a terrific historical retrospective. I remember a couple of flights on DC3's when I was about 3-4 years old.
Sure makes one itchy to build a DC3!
Andy
Final report:
- connected the rudder and elevator servos. Used very thin piano wire inside full length aluminum tubes.
- soldered the two sets of ESC wires to a JST battery plug and joined the radio wires via a small "Y" connector.
- connected the ailerons to the two wing servos. Used thin piano wire.
FINAL WEIGH-IN. Total weight- 15.1 oz.
Fuselage- 4.7 oz
Wing with motors and ESC's- 8.0 oz.
battery 3S 800 mah 2.4 oz.
Will it fly? Each motor has a max of 110 watts. That's 233 watts per pound. Oops. I think I overdid it, especially since two separate motors produce more thrust than one motor with the same wattage.
Meets the Modeller's objective: "Always overpower a model airplane. You can always throttle back....if you have to!"
Frank
Quote from: Frank v B on February 03, 2021, 09:20:38 PM
Final report:
- connected the rudder and elevator servos. Used very thin piano wire inside full length aluminum tubes.
- soldered the two sets of ESC wires to a JST battery plug and joined the radio wires via a small "Y" connector.
- connected the ailerons to the two wing servos. Used thin piano wire.
FINAL WEIGH-IN. Total weight- 15.1 oz.
Fuselage- 4.7 oz
Wing with motors and ESC's- 8.0 oz.
battery 3S 800 mah 2.4 oz.
Will it fly? Each motor has a max of 110 watts. That's 233 watts per pound. Oops. I think I overdid it, especially since two separate motors produce more thrust than one motor with the same wattage.
Meets the Modeller's objective: "Always overpower a model airplane. You can always throttle back....if you have to!"
Frank
Perfect! Now you can fearlessly practice one-engine-out maneuvers!! 8)
Congrats
@Frank v B !
Beautiful!
Just prepped it for a maiden flight tomorrow (Sunday, June 20) at Rogo Field.
Put in a 370 mah 3 cell pack. Fingers crossed. Say a prayer.
Frank
The re-maiden went well today. Managed about two circuits of the field and brought it in for a landing. It did a cartwheel in the beans but it survived unscathed. The only thing damaged was my ego having to do the walk of shame through the beans again. ;)\
Note the amount of "down" elevator in level flight. That's how I had to fly straight and not-so-level.
Photo by Andy.
Frank
Here is
@Frank v B 's large-scale DC-3! ;D
n.b. Frank-style soft focus on #3938. :D
A great airshow by Frank!
Andy