Curtiss Seahawk (oz13570)

 

Curtiss Seahawk (oz13570) by W Esposito 1956 - plan thumbnail

About this Plan

Curtiss Seahawk. Control line scale model biplane fighter.

Quote: "Curtiss XF-7-C3 Seahawk, by W Esposito. A 1 in to 1 ft scale control-liner for 3.5 - 5 cc engines.

THE XF-7-C3 Seahawk is a not so well-known edition of the fabulous Curtiss Hawk series, which set the standard for fighter aircraft the world over for more than 20 years. This particular version was developed mainly for the export trade, and saw service in South America and the Orient. However, the US Navy did become interested, and tested the machine, thus the designation. There is not very much data available on this aircraft, and the colour scheme and marking are taken from the standards of the era.

The model is built to a scale of 1 in to 1 ft, giving it a wing span of just over 32 in and an area of 273 sq in. Power is an 0&R 0.29 which fits the cowl nicely, and is just the right length to put the prop at scale distance from the firewall. A 9-1/2 in prop is scale, too. All up weight is 25 oz.

Cowling and Lower Wing: Now to get down to work. First, the engine speed ring. Cut 16 pieces of part C-1 from 3/8 soft balsa. Measure the maximum diameter of the ring on the plans, and lay out a circle with a compass to that diameter. This will be used as a guide for all work on the cowl and nose block. Build up the laminations for the ring on the circle you have just laid out, being careful not to get all the butt joints of each segment in line. Allow to dry thoroughly. Sand to shape and apply plenty of filler. This part, along with the large wheel spats, is the eye catcher, and should be well finished. It is built first to allow the filler to shrink into the seams and then more filler is applied. It takes a lot of sanding to get it looking good, but it's worth it. You can work on this between other jobs while the cement is drying.

Next, the lower wing. This has to be ready to mount at an early stage. Cut out the leading and trailing edges, and lay out the rib stations along the length of the edges, and notch. Cut the


ribs from 1/16 medium sheet, except for the two ribs at the strut stations - these are 1/16 ply. Cut away the sections of the leading and trailing edges as shown. Insert the ply ribs into the proper notches in the trailing edge and line up. Now cement the leading edge in place, and insert the rest of ribs, checking constantly for alignment. Cut the tips to outline shape and cement into position. Add the gussets at the corners and about an ounce of lead to the starboard tip; the upper wing is built in the same manner later on.

Both wings can be built in the hand without pinning down to the table. Exercise extreme care in cutting the scarf joint splices for the leading and trailing edges of the upper wing. The centre section of the trailing edge will have to be made from flat stock, as the joint prohibits the use of pre-formed stock for this. Remember to notch the edges at an angle for the upper wing, due to the sweepbaCk. After all the ribs are in place, add the strut sockets as shown on plan.

Fuselage: Cut the box sides and spacers from 1/8 hard sheet, and score the sheet sides on the inside at the point where the taper begins in the top view. Insert the spacers at stations 2, 3, 4 and 5. When dry, draw the tail ends together, glue, and insert the rest of the spacers. Make sure that the box is perfectly square. Decide what engine you are going to use - I used an inverted 0&R 0.29, radially mounted, but a Frog 500 will do just as well. Drill the firewall to take the crankcase studs, making sure that the crankshaft is on the aircraft centre line. Solder the crankcase nuts to a piece of tin and fix to the back of the firewall. Mount the firewall.

Install the fuel tank, followed by the ply landing gear platform, then the tail wheel struts, tailplane and vertical fin and the centre section wing struts. These struts are bound and glued to the 3/8 x 1/2 in cross pieces indicated on the plan. Sheet the lower wing roots with 1/16 and the fuselage with 3/32 as shown. Mount the engine and build up the nose block around it, taking care to glue the nose block to the firewall lightly as it will be removable. Remove the engine and carve the block to rough shape.

Now cement the fuselage formers into position. These are cut from 1/8 sheet and sanded to cross section, then filled in between with 1/8 sheet at the indicated stations to imitate stringers. Note that the lowest stringer on the fuselage side is set at an angle and runs along the edge of the box.

Now build up the landing gear spats and struts. Drill a piece of tin to take the bolts which will hold the removable spats and struts together, and solder these to the outside of the wire strut as shown. Cut the ply doublers to shape and bolt into position. Be sure that the parts do not stick together. This can be done by placing some wax paper between the separating parts. Glue the sheet which forms the main portion of the spats to the ply. Build up the main strut from 1/8 hard balsa laminated. Run the wax paper up between the separating parts. Build up the fillet where the strut joins the spats, then the fillet at the fuselage. Note that the upper fillet is separate from the strut. Leave plenty of room at the upper fillet for the wire strut to move around. Carve and sand to shape. Note that the top edge of the spats is a sharp edge and not rounded.

Add at this time the rudder and elevator. The rudder should be offset as shown (to the outside of the circle). Make the elevator in two pieces and glue to a 3/16 dowel for a spar. Mount the horn. Install the elevator before the rudder. Don't forget to make the push rod the exact length, at the same time ensuring that you can adjust the horn movement as necessary..."

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Curtiss Seahawk (oz13570) by W Esposito 1956 - model pic

Datafile:
  • (oz13570)
    Curtiss Seahawk
    by W Esposito
    from Model Aircraft
    June 1956 
    32in span
    Scale IC C/L Biplane Military
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 10/01/2022
    Filesize: 517KB
    Format: • PDFbitmap
    Credit*: KraftyOne
    Downloads: 394

ScaleType:
  • Curtiss_F7C_Seahawk | help
    see Wikipedia | search Outerzone
    ------------
    Test link:
    search RCLibrary 3views (opens in new window)


    ScaleType: This (oz13570) is a scale plan. Where possible we link scale plans to Wikipedia, using a text string called ScaleType.

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Scaling

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