waroff

to be accurate, you can make two templates from strong paper, trapezoidal in shape, when they are on the stabilizer the upper edges must be aligned with each other. the edge is at 4° 10 or 7.19% slope.
the dihedral of your model is convincing, that’s perfect.

This is not very scientific, but it's close enough to 4 degrees for me.  
 

The tailplane dihedral was 4° 10' measured at the upper surface of the stabilizer spar

The tailplane dihedral was 4° 10' measured at the upper surface of the stabilizer spar

The tailplane dihedral was 4° 10' measured at the upper surface of the stabilizer spar

hth 

this is the spark plug cooling tube, it also exists on the N, but further back maybe (D up to N these tube are same part number)

hth 

hth 

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this is the spark plug cooling tube, it also exists on the N, but further back maybe (D up to N these tube are same part number)

Some picture
 
the color blue was blue varnish (Lionoil prussian blue)
All part in Alclad receive one coat of this varnish before assembly. The coat was not removed yet.
This H-75 A9 receive left aileron from another aircraft.
 
Some part received one coat of primer yellow zinc chromat, air fillets was bare metal.
Around each hatch we can see the coat of primer tinted green color sprayed over over the yellow zinchromat.
 
 
For paint the model, I spray Alcald II aluminium. When this coat is dry, I spray several coat of "blue transparent"(Alclad II)
 
The model is not finish.
 

 

 

 

this is the spark plug cooling tube, it also exists on the N, but further back maybe (D up to N these tube are same part number)

this is the spark plug cooling tube, it also exists on the N, but further back maybe (D up to N these tube are same part number)

and the drain holes on P40/H81 window frame

HTH
 

HTH
 

similar to curtiss 75 (drawing), the bottom of the rear window frame on P40B/C and H81, had also nine drain 1/4" holes,  and 6" apart, but fluids drain through only some of the holes giving the impression of only three or four holes
 

read in Curtiss spec for P 36 and P 40 Army airplanes, july 39
"
**C-1b.               Clear primer for aluminium coated (alclad) aluminium alloys.    clear varnish type coating (Lionoil or equivalent) shall be used as a shop coating to prevent scratdhing of the sheets during fabrication. This coating shall be used as the primer coat on interior surfaces of metal skin.
 
 
**C-1c. Yellow green finish. the yellow green finish coatong specified for general interior finish shall be prepared as follows               
Zinc chromate primer                   1.0 Gallon
                Enamel, black                                   0.1 Gallon
                Aluminium paste                            4.0 ounces
                Toluol                                                  2.0 Gallon
 
 
....
E. DETAIL REQUIREMENTS.
 
 
 
...

 
**E-10  Finish for interior parts and surfaces.
 
**E-10a.              The finish for interior parts and surfaces shall be as follows:--A greater number of coat of primer or finish may be added at the discretion of the manufacturer;
**E-10b.             Wings, control surfaces, engine mount and fuselage, excepting compartment for personnel and **E-10b (1).         One thin coat of metal primer and one coat of yellow green finish before assembly and one coat of yellow green finish after assembly.
**E-10c;              Cockpits. Cockpits shall be finished with one coat of primer and one coat of yellow green finish before assembly and one coat of yellow green finish after assembly.
..."
 
and Curtiss spec for export airplanes, sept 39:
 
"- 5.521  All alclad 24ST used as skin covering for wing, fuselage, tail surfaces, and other parts fabricated in the heat treated conditions to be coated both sides with blue Lionoil shop coating, or equivalent, prior to fabrication and assembly.After assembly all Lionoil exposed on exterior to be removed to leave natural alclad as the exterior finish. Lionoil to be left on the interior.
...
- 5.525  The interior of the entire fuselage, and parts enclosed therein to be given one coat of the following mixture to produce uniform and satisfactory appearance:
COCKPIT COATING FORMULA
                One gallon zinc chromate primer
                one-tenth gallon black enamel
                Two gallon of Toluol
                4 ounces aluminium paste
 
....."
 
Below, cockpit green seen on french H75A3, note the prussian blue lionoil which is left as primer as prescribed by Curtiss spec.

 

 
H75A2
interior surface of fuselage door and it inner closed surface

 
 
 
 
 
 

and the drain holes on P40/H81 window frame

auto-adhesive masks for pilot's canopy, there are some details to fix;
trials on matrix
 

.
[i]the windows are precut out from 0.014 plexi sheet. It is indeed plexi (pmma), therefore sandable and polishable. bend slightly along the cutting line and the part easily detach from the sheet.
.[/i]
[img][/img]

[i]An adhesive strip stuck across allows them to be positioned in place for their adjustment, then for their
maintained during their gluing
gluing the glazing(CA, liquid glue) on their free edges with a tooth pick(I use a "pique huile") , then later, after removing the adhesive strip, complete the gluing on the entire perimeter.[/i]
[img][/img]

auto-adhesive masks for pilot's canopy, there are some details to fix;
trials on matrix
 

auto-adhesive masks for pilot's canopy, there are some details to fix;
trials on matrix