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Dec 27, 2019, 08:24 PM
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Build Log

P-51B Ding Hao Build Log

This build log goes with the P-51B Pony plans drawn by Norman E. Meyers available on 57.5” wingspan, 1/7.5 scale.

This build log includes suggestions and many scratchbuilt elements including:
:: cockpit with pilot and radio
:: center tray connecting wings
:: balsa / ply wheels
:: electric conversion
:: unique ribs
:: weathering details
The plans state this plane has a 57.5” Wingspan, but with the center “tray,” it is 62.75 (1/7). The length is 50” (1:7.5)
Equipment used on this plane: .46 Rimfire Motor, 70 ESC, and 6 servos
Callie Graphics and Aces of Iron WW2 Pilot
Last edited by UpNup; Jan 31, 2020 at 03:44 AM.
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Dec 27, 2019, 08:34 PM
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The rudder and elevator are good places to start. However, when I went to epoxy the elevator to the fuselage frame, I learned that the center support of the elevator needed to be wider and put into place before the hatching on the turtle deck. I decided to plank the stab and front elevators with 1/32” ply, but 1/16” would be much better.

After cutting out all the pieces, I noticed the elevator’s side view diagram. It’s on the plans, but up beyond the bottom view of the fuselage. I set up two sanding sheets and after gluing everything with TiteBond II and let set for 30 hours, I heavily sanded the elevator to the plans. (whew) But. I broke a rib and realized how fragile it was. I inserted ½” X 1/8” shims between the ribs.

Wings were cut out by using a micro-blade saw and an hobby knife. The LE leading edge had a joint that was bonded with 5-minute epoxy. Servos had to be built into the plane as it was constructed. The landing gear area has ply doublers. I chose to only sheet half the wing top and bottom.

The tricky part was getting the R1 Root Rib to lean at a 3 degree angle to accommodate the dihedral. I used a protractor and guess a lot. Note my building surface was an exercise mat 1” thick. Pins stuck to it and it was firm, but soft. Blue painters tape stuck to it. I used wax paper from Dollar General, as it is waxed on both sides.

The servos on the ailerons had an extension wire that connected to a Y-harness. This will be used with a 6-channel radio (Spektrum Dx6e.)
Dec 27, 2019, 08:42 PM
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It is possible to cut 1/8” basswood ply to make the formers without professional equipment. All I used to cut was a micro-saw and an X-acto knife. It’s not exact, but with lots of patience and some good sanding techniques, you’ll make some good progress.

As soon as I could, I made the cockpit. I still don’t know why, but it was one of the most challenging and rewarding parts of the build. Note the I sunk the floor of the cockpit by ½” to make it look more realistic from stand-off distance.

The formers are straight; the camera wide angle bent the photo edges a bit.

A Styrofoam cooler makes a great cradle for the plane during the build. I put black Gorilla tape along the edges as a cushion and to keep white beads from constantly breaking off.

The tail wheel was put into place as soon as the fuselage was built. I guessed on the wire, but used 1/16” wire. The tail wheel was anchored with straps and put into a basswood ply base – 1/8” thick. It was covered with 1/16” balsa.

Before the fuselage hatch and bottom is planked, it’s necessary to build a balsa platform that will house the battery (top) and the ESC and Receiver upside down. On the right of the photo, the black boxes are the servos in place for the rudder and elevator.

The red tubes are Sullivan Gold-n-rods that run through formers in the fuselage back to the tail fins.
Dec 27, 2019, 08:46 PM
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Balloon wheels required for the P-51B are readily available for about $12 plus shipping cost. Still trying to be frugal, I thought I’d make my own. This required research. The plans call for 3” wheels up front and 1” diameter dragging behind. Math on scale put my width at 15/16” thick wheels. I used several layers of alternating ply and balsa to achieve the desired effect. The hubcaps on the front wheels are 1/32” thick. I learned that my hole punch could handle Ό” circles.
Dec 27, 2019, 08:54 PM
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The cockpit was challenging and very rewarding.
Use Zinc Chromate color on interior.

Pilot is from Aces of Iron. A Ό” base could raise the pilot up a bit, but 1/7 scale pilot was a good and realistic fit.

Seat back and pads are painted balsa

Radio is balsa block, but could be built up from 1/8” balsa sheet.

Antenna base in roof is tip of a flag stick. Round dowel nubs on radio box and snorkel are from the same flag stick. Radio could be up to ½” higher to show more in window.

Use .3 plexiglass – it can be cut with scissors and curved with a heat gun over a curved balsa block. Here was a first attempt.

The cockpit uses a photo of a P-51B dashboard sandwiched between a .030 clear plastic sheet. The cowl is balsa covered in pleather. Scratchbuilt is a N3B gunsight.
Dec 27, 2019, 08:57 PM
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Making a Balsa Cowl

The cowl required formers and planking. It was necessary to have the motor mount in place and to have the front ply formers in place with two balsa spacers between them. Note that the cowl is being held on with rare earth magnets and metal cut from discarded razor blades. In the final photos notice that the openings have been cut for the exhaust stacks. These extend beyond the cowl, cut into the front of the fuse.
Dec 27, 2019, 09:15 PM
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Making Exhaust Stacks

The original plans did not have any plans for exhaust pipes. These are one of several scratchbuilt ideas built for pennies.

The exhaust stacks are not just doo-dads stuck on the sides. They are hollow and help the airflow through the airplane. There is a radiator exhaust gate that is hollow in the back (no photo). The bases were sanded from balsa strips. Holes were cut at an angle. Sections of a window blind plastic control rod was cut, sanded and painted. The pipes were painted black and dusted with tan chalk, but need to be further lightened.

The stacks are epoxied to the cowl, but just slide into a channel cut in the fuselage.
Dec 27, 2019, 09:26 PM
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The P-51B is coming along. One decision is to be made regarding a final side sheeting to the fuselage. At present, the sheeting was 1/16” basswood covered by 1/16” balsa sheets.

Planking is according to the plans. I cut the hatch on a diagonal line to match the angle of the top panel.

One problem was the elevator. The fin portions are epoxied in place with wire. It needs to be practically finished, covered, and hinges glued into the front of the elevator before affixing to the fuselage. This needs to be done prior to finishing the turtledeck and the fin/rudder is epoxied in place.
Dec 27, 2019, 09:33 PM
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The wings are joined under the fuselage in a special tray that is 5” wide. This is how the WS totals 62.75”. The plans did not match the formers used in the fuselage.

I was advised to complete the fuse and wings first and then work on this custom-fit aspect. I hope these photos help give some ideas in 3D what the plans were trying to communicate. Most of this tray was made from basswood, including the spars and dihedral braces.

The challenge is that the tray needs to sit up into the fuselage by Ό”. This meant building a secondary wall out to the fuselage. It is built upside down.

This is where the dihedral braces and the scoop come into play. It really is a 3D jigsaw puzzle with lots of things coming together. And the wings must be epoxied to the tray for it to work correctly. Whew!
Dec 27, 2019, 09:36 PM
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Yes, I used a $1 foam cooler as a building base for the fuselage. The delicate canopy can fit down into it nicely. I used black Gorilla tape to keep the Styrofoam from flaking. It's soft, too, and has never scratched or marred anything.
Dec 27, 2019, 09:45 PM
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At every step it seems there is something new to learn. I learned that there is such a thing as Monokote FLAT Olive Drab. After buying two rolls of Olive Drab that was nice and shiney from my LHS, you would have thought he’d have mentioned it. I also used one roll of gray and decided to buy white to use on accent pieces and future builds. The dark OD did not show through the white. I did the bottom first and then the top. However, the dark OD Monokote would still need to be weathered.

To put Monokote over the elevator wire, I measured and cut a slit.
I cut up a t-shirt and use wooden clothespins to form a sock over the iron.
I like to keep the heat up high on my iron.
If you look at the “grate” along the green/gray line, I matched paint to the Monokote gray. Barely noticeable.

The white stripes denote the European Theater Allied airplanes or so I was told. These are not paint, but Monokote strips. I followed a nomenclature guide that gave precise measurements and width.
1. Measurements placed the real wing stripes 40” from center and 15” wide. Rudder stripes came down 18” and 12” wide.
2. I used the scale measurements to put Sharpie dots which were later wiped off with alcohol. After a day of drying, the ETO stripes were ready to iron with medium heat.
3. Wing strips were 2” wide and I cut them 16” long. Stripes on tai feathers were each 1.6” wide (1 5/8”) and I cut them 6” long. I cut the hinge gaps before the strips were dry.
4. The wing strips were placed 5.5” from center of plane. The elevator strips were placed out 4.75” from center of plane. The rudder stripes were placed 2.4” from the top.

Application included wetting the glue side with Windex, laying it over the OD Monokote. I squeegeed out all the bubbles and allowed it to dry 24 hours. Put your iron on medium heat and softly go over all the white stripes. They won't shrink, but they will stick very nicely.

After applying the Monokote, I began weathering by rubbing 400 grit sandpaper in the airflow. I dipped the paper in water to wet sand any residue and keep the sandpaper from becoming slicked-over.
Dec 27, 2019, 09:47 PM
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Panel lines were too wide with a Sharpie fine marker (photo with blue tape). I used acetone to wipe the lines off. The Sharpie Ultra Fine Point left much less obvious panel lines.

Callie Graphics has the scale graphics and they also have all the nomenclature for signs. They also have a scale instrument panel, which I found out after completing the canopy.
Last edited by UpNup; Dec 27, 2019 at 09:53 PM.
Dec 27, 2019, 09:59 PM
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Weathering for my P-51B followed this sequence:

1. Scour Monokote with 400 grit sandpaper. Dip in water to keep the sandpaper clean. Move inn the direction of airflow.

2. Add graphics. I used Callie Graphics and made some of my own water-slide decals for nomenclature, gas caps, camera access panel, etc.

3. Chip panel edges and cockpit edges with a fine art brush and Testors aluminum enamel.
Use 0000 grit steel wool to gently dab paint chips on LE, certain panels, and places were crew members walk.

4. Mark major panel lines with an Ultra Fine Point Sharpie. Lay out lines with blue painters tape and carefully draw straight lines.

5a. Option—mark rivets with a small brass tube heated with a soldering iron on low. I passed.
5b. Option to airbrush: Shave brown, dark gray, and a rust color into a pan. Use a soft wide brush to stroke streaks on the surface. Use blue painters tape this way: horizontal put the tape upwind. On vertical lines put the tape on the outside of the line and stroke toward the plane.
Don’t be shy with the chalk. It melts away a lot with the matte spray.

6. Seal top surfaces with clear matte spray. Then flip plane over and stroke chalk on the bottom side. Spray clear matte spray over the bottom.
Dec 27, 2019, 10:01 PM
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The weathering brought everything together. I look forward to balancing and tweaking the plane. I let my flying skills go to build, so I'll look to fly this in a few months.

Thank you for reading this build log! Comments are welcomed.
Dec 28, 2019, 06:00 PM
I just want to go fly!
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Looks great. Love the cooler stand idea. Flight report?

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