14" span Pitts biplane- go big or go home!! Frank's Covid build #5

[Frank v B]

I still have a few more hours of work on the DC-3.  Once I have completed it I will build this biplane.

This will be the 4th one I have built.

Pitts 1- 18" span (150% enlargement) with an E-Flite 280 on 3 cells- flew well
Pitts 2- 14" span (115% enlargement) with an E-Flite 180 on 3 cells- ballistic and flew it in 30 kmh winds
Pitts 3- 12" span- as per the original plans with an E-Flite UMX radio system- See photo below next to a roll of Scotch tape. Indoor only, marginal power.
Pitts 4- this one 14" span- 115% with an E-flite 180 on 3 cells.  Same as Pitts 2.

The plans are a free download on the website:   https://dragif.com/pdf/aIBV?epik=dj0yJnU9ZTZoN2RIWndTLWVJblZVUTlLeDY2ZGVPNzdWZWxkcHMmcD0wJm49dzY1T3lfR2tGSnJXX3BaRE1FSmVjdyZ0PUFBQUFBR0FaXzAw

I printed them at 115%.

These things are a blast to fly and impossible to land properly.  The best way to land is fly over tall grass and cut the throttle.  When they slow down to a certain speed they just tumble out of the air.  A repair required every flight.

They are easy to build and only take about 10 hours.  4 channel.. with ailerons.

Frank

[msatin]

I've seen UMX, but ...... this is a whole new level!
This very cool Frank

[Frank v B]

Mark,

The one you saw me fly at TEMAC was the large Pitts #1  (18" span). 
The smaller 14" one I am going to build is much faster and much tougher to fly.
I flew it on 3 cell 100 mah batteries.

Frank

[Frank v B]

Let's get started.

Picked up the new E-Flite 180 motor at John's Hobbies today.
Found 3 small servos and a Berg receiver (72 meg- with long antenna). 
See photo.  A dime shows the relative sizes.  The motor is a little gem. Note the dental floss on the servos.  They pop apart (no screws) without dental floss and a drop of glue.

I use a 72 meg receiver on these small planes for two reasons:
1) the trim levers can be shoved over immediately if it needs immediate trim.
2) for the take-off.  I stand on the antenna, give full throttle, give full "up" elevator and release the antenna.  The take-off roll is measured in inches (about two!)
It is almost impossible to do a normal throttle-up, pick up speed and rotate for take-off routine.

Now I will look in my balsa forest for the woody bits.

Frank

[Frank v B]

Cut out all the parts.  The fuse sides and wings are 1/32 balsa.  The firewall, formers and ribs are 1/16.

Tomorrow we start slobbering glue onto the building board.  Only one joint is glued on the board.  The rest of the fuselage is built in mid-air.
It's a really interesting... and strong process.

F.

[Frank v B]

The only glue joint on the building board.  The back of the fuselage is joined together.  It is the turtle deck behind the cockpit. (the knife blade points to it).

F.

[Frank v B]

Building the fuselage:

Step 1- dampen the wood by laying it between two wet paper towels.  Half hour is fine.  Photos 98,99
Step 2- lay wax paper on your hand* and place the fuselage on top.  Use your thumb and middle finger to curl the wood. Photo 00
step 3- Insert F2 at the back end of the cockpit cut-out and glue.  Hold until dry (1 minute?) I used medium CA. Photo 01
Step 4- squeeze the back end together and glue.
Step 5- glue the top deck of the fuselage together at the front of the plane and hold until dry.
Step 6- insert F3 just ahead of the stab slot and glue.
Step 7- Insert and glue the firewall to the fuse top and sides with down thrust and right thrust.  How much?  Just enough! (3 degrees each?  the instructions say 3 and 6).  Leave the bottom unglued because this has to be trimmed to fit..
Step 8- double-cut the bottom fuse sheeting to make it all the way around the firewall.

Fuselage is finished.  Photo 02.
 
Total elapsed time was 8 minutes and that included taking the photos.

Frank

*if you use fast CA you will learn "why?" immediately!

[GuyOReilly]

Cute as a button!!! And about the same size too! 

[Frank v B]

Thanks Guy.

Da Wings.

Step 1- Pinned the ribs onto the plans. Two ribs on each lower wing half and three ribs on each upper wing half.  The only change versus the plans is that I made the ribs longer so they would stick out of the leading edge and trailing edge so the pins would not get in the way.
Step 2- wet the wing halves.  Top surface only.  Put a wet paper towel over the top only.  Photo 03. 
Photo 04 shows the curves caused by the water treatment.
Step 3- take each wing half, run a bead of medium CA over the ribs and hold the wing down until the glue cures (30 seconds).

It took longer to pin the ribs onto the plan than it took to build the wings.  Total time for pinning and gluing: 20 minutes.

Frank

[Frank v B]

Next Steps:

Hinging the rudder and elevator- The first time I tried this.  Used pieces of rubber band as hinges.  Cut slots in the elevator halves and stabilizer and fin and rudder.  The pieces of rubber are laid in the slots and one drop of CA and......miraculous.  Works beautifully  On previous planes I have used clear medical bandage tape (Blenderm) but they eventually let go.  See photos 10 and 13.

Cut the bottom wing slots through the fuselage.  The bottom wing halves are slipped into the slots and glued in place and joined in the center.  The part of the fuselage below the wing becomes the root rib.  Photo 14

Servo installation: Installed one balsa servo rail with 5 minute epoxy.  Once dry, I will install the second rail.  The 3 servos are side by side but the aileron servo is installed upside down so the horn sticks out of the bottom of the fuse.

Frank

[Frank v B]

Servos installed.

View from the top (photo 15)- the rudder and elevator servo visible. The center servo is for the aileron and is installed upside down.
View from the bottom (photo 18)- the aileron servo is sticking up from the center.  Note that I left some bottom sheeting open to help in routing and attaching the servo control rods.

Frank

[Andy Hoffer]

Servos installed.

View from the top (photo 15)- the rudder and elevator servo visible. The center servo is for the aileron and is installed upside down.
View from the bottom (photo 18)- the aileron servo is sticking up from the center.  Note that I left some bottom sheeting open to help in routing and attaching the servo control rods.

Frank

So @Frank v B , where exactly do the IKEA instructions fit into this beautiful piece of aeronautic jewelry?!!! 

Andy

[Frank v B]

- tail feathers glued in place
- bottom wing joined inside the fuselage
- photo of the bottom shows the wing joint.


photo 22- just had to do it. 

F.

[Andy Hoffer]

- tail feathers glued in place
- bottom wing joined inside the fuselage
- photo of the bottom shows the wing joint.


photo 22 23 - just had to do it. 

F.

@Frank v B has taken ARF's to a whole new level with the addition of knock-down hardware and the provision of the required assembly tool, which also doubles as a starter crank for his seized up brushless motors!.

Andy

[GuyOReilly]

@Frank v B , what will the colour scheme be? Starburst?  Painted feathers? Monochromatic? Fluorescent?
Asking for a friend...