El Conquistador (oz7501)


El Conquistador (oz7501) by Clair Sieverling from American Modeler 1958 - plan thumbnail

About this Plan

El Conquistador. Control line stunt model.

Quote: "El Conquistador means 'The Conqueror' and built correctly I think you will find the plane will live up to its name. It was designed for the serious stunt flyer, but with consideration for the novice, too, Construction is simple and doesn't require hours of painstaking work. You'll find that your copy will go through the pattern with the best of them; its looks will draw more than a few admiring glances from fellow modelers.

Let's start with the wing; take your time here, a warped wing will ruin any stunt plane, so check carefully for warps as you progress. As for cement, I prefer a slow drying type that soaks deeper into the wood and gives a more firm joint. It's also a good idea to double-cement any joint that will bear much stress; apply a first coat and after it has dried apply a second coat over the first, letting this coat dry thoroughly before putting any strain on the cemented pieces.

Start with the bottom spar which is 1/4 x 1/2 in balsa. Mark off the rib locations, adding one extra rib section on the inside (left) wing which is longer than the outside wing to maintain line tension. Cement a brace of balsa 1/4 x 1/2 x 6-1/2 in to the trailing edge of the spar at the center splice. Cut the ribs from 1/4 sheet and position them on the spar according to markings, but don't cement them at this time. Add the leading and trailing edges of 1/4 sq balsa, using pins where necessary to hold the strips in place. Use the full 36 in length of the strips; avoid making all the splices in the center of the wing. Add the top spar of 1/4 sq balsa; check to make sure the entire assembly is free of warps. When satisfied with the alignment, glue each joint and put away to dry. Later go back over each joint with a second coat of cement, then let dry completely before continuing work.

Continue construction by cementing the 1/8 in plywood bellcrank mount on the bottom spar and spar brace; when dry, the bellcrank and lead out wires may be installed. Solder the lead out wires securely, and check the movement for any stiffness or friction. I prefer to solder the bellcrank nut to insure against it vibrating loose while in flight. Apply a few drops of oil to the pivot to keep the acid from the solder from sticking the bellcrank. Better to spend a few minutes of precaution at this time and be sure - it's a terrible feeling to have the controls pull out in flight!

Add the 1/16 in trailing edge planking, plank the leading edges with 1/16 sheet, then plank the center section, leaving an opening above the bellcrank to allow installation of the control rods. Cut and cement 1/4 x 1/16 cap strips to each rib; attach the wing tips, which are 3/32 balsa with 1/8 sq rim around the edges to give more area for the covering to adhere to. Add 10 in of solder to the outside wing tip; this should be sewn in place with heavy thread and cemented securely.

Cut out the flaps, taper their trailing edges, join with the large size metal elevator horn, and attach to the wing with heavy cloth hinges. Cut and bend a push rod of 1/16 steel wire and hook up the flaps with the bellcrank. Flaps should move a maximum of 20° up and down. Check once more for warps; if any are found take them out with steam. Use either Silkspan or silk for covering. The original El Conquistador was covered with the so called 'silk' scarves available through most five and ten cent stores; it is in reality part silk and part rayon, and gives a very strong covering. Put it on wet and stretch it as you go, using thinned-down cement as an ad-hesive.

Now for the fuselage. Sides are cut from 1/8 sheet. Also cut two nose doublers the same size as the fuselage sides; these extend back to former #4, and are of 1/8 sheet. Cement the doublers to the fuselage sides; when dry cement the 5/16 x 1/2 in hardwood motor mounts in place. Cut out the formers #2 and #3 from 1/4 in plywood and drill #3 for the landing gear 'J' bolts..."

Direct submission to Outerzone.

Update 25/08/2021: Added full article, thanks to RFJ.

Supplementary file notes



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El Conquistador (oz7501) by Clair Sieverling from American Modeler 1958 - model pic

  • (oz7501)
    El Conquistador
    by Clair Sieverling
    from American Modeler
    March 1958 
    48in span
    IC C/L
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 17/02/2016
    Filesize: 700KB
    Format: • PDFbitmap
    Credit*: dfritzke

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User comments

Thanks to Pit for clarification on this one.
SteveWMD - 26/02/2016
The article on this one is incomplete :-(
RC Yeager - 24/08/2021
Fixed :)
SteveWMD - 25/08/2021
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  • El Conquistador (oz7501)
  • Plan File Filesize: 700KB Filename: El_Conquistador_AT_3-58_oz7501.pdf
  • Supplement Filesize: 3211KB Filename: El_Conquistador_AT_3-58_oz7501_article.pdf
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