Jack O Diamonds (oz14977)

 

Jack O Diamonds (oz14977) by John Reid 2002 - plan thumbnail

About this Plan

Jack O Diamonds. Free flightl sport pusher model. For electric power with geared 130 motor.

Quote: "Fancy something different, this little jewel should be right up your street. As many older readers will have guessed, my starting point for Jack O'Diamonds was George Wools' Ace of Diamonds (oz3711) from Aeromodeller, Aug '58. At first I meant to make a smaller copy. But a closer look at the drawing soon changed my mind. The original Ace of Diamonds was a complex model that would become impractically intricate when scaled down. With some trepidation, I set about creating a simpler version of this masterpiece.

As it happened, just one initial compromise led to a domino-like cascade of simplifications. Jack O'Diamonds is easier and quicker to build than most conventional models.

The major change was to build the wing flat on the plan (the original had the rear part of the wing sweeping down to the fuselage and was built in mid-air). This change greatly simplified wing construction and led to simpler wing attachment and fuselage construction.

The other major change was to substitute one (rather large!) fin, integral with the fuselage, for the two mounted precariously on the rear part of the wing.

Do these changes sacrifice the aerodynamic advantages claimed for the Warren Young diamond wing? Maybe. The Warren Young wing is supposed to gain efficiency by controlling wing tip vortices. I suspect that a lot of tuning in a wind tunnel would be needed to realise these advantages in practice.

Jack O'Diamonds is a fine flier anyway, very stable and easy to trim. It won't win duration contests, but has a steady and almost stately look in the air.

For what it's worth, I think the main advantage of this wing form is structural, rather than aerodynamic. The one-piece wing gives great rigidity and warp resistance. The excellent stability is probably due to the low aspect ratio tips, which keep on lifting after the rest of the wing has given up. They are well behind the CG too. Also helpful is the high thrust-line and low CG, which works like part-time down-thrust that only kicks in when the nose is too high.

BUILD NOTES: Do read these building notes because bits that look tricky on the drawing are, in fact, easy. Make two or three photocopies of the drawings so that you can cut patterns and don't have to wait for the glue to dry before starting another section.

WINGS: Make a template from thin aluminium or ply for cutting out the ribs. This template can be used for R2 and R3 as well. Pin down the leading edges and trailing edges flat on the plan, without twist at this stage, and glue the ribs and spars in place. It would be OK to make the tips from 1.5mm sheet instead of laminating them. The inner ribs are tilted a little for dihedral and aligned off centre to allow for the twist that we are going to add in a moment.

The wing twists are added after the glue has dried. Paint the whole structure with water, pack up the inside leading edge of the front part of the wing and the inside trailing edge of the aft part of the wing by 3mm, and allow to dry. I used aliphatic resin glue, which probably softens a little when wet and helps this process. Purists frown on this method, but purists should be building George's original Ace O'D anyway!

The wings can then be covered. I used tissue because that was what was available when I built the model. I would use 'Airspan' now. Shrinking and painting can be done after the wings are attached, because further warping is resisted by the interlocking structure.

FUSELAGE: Don't cut the slot for the fin until the bottom part of the fuselage is complete. Pin the fuselage base (the top of the bottom of the fuselage) to the plan. Bend the undercarriage, bind and cement to C1, and glue C1 in place..."

Direct submission to Outerzone.

Jack O'Diamonds from R/C Model Flyer, December 2002.

Supplementary file notes

Article pages thanks to RFJ.

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Jack O Diamonds (oz14977) by John Reid 2002 - model pic

Datafile:
  • (oz14977)
    Jack O Diamonds
    by John Reid
    from RC Model Flyer
    December 2002 
    21in span
    Electric F/F Pusher
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 29/11/2023
    Filesize: 431KB
    Format: • PDFbitmap
    Credit*: Circlip, RFJ
    Downloads: 486

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Jack O Diamonds (oz14977) by John Reid 2002 - pic 007.jpg
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Jack O Diamonds (oz14977) by John Reid 2002 - pic 008.jpg
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Jack O Diamonds (oz14977) by John Reid 2002 - pic 009.jpg
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User comments

I think this model is for free flight, not R/C. I dont see any servo and the rudder and elevons are trim tabs.
Martin - 10/12/2023
Doh. FF not RC. Thanks, got it :)
SteveWMD - 10/12/2023
Hi Steve, if I remember correctly, there was an article about diamond wing flying models in the german "Flug Modell" magazine around 1973. He also tried dihedral on the front wings and anhedral on the stabilizer. The author had been experimenting with this particular geometry for quite some time, finally achieving good results both as gliders and motorized - but only in free flight. His impression was that control inputs worked against the inherent stability of this layout. Cheers, Martin
Martin - 10/12/2023
Hello friends, One of my friends asked me about Jack-O-Diamond [pics 007-009] as I flew one just after the Millennium shift. Not very nice built with the linear servos just glued to the starbord sideā€¦ It flew quite well and was very stable, and was powered with geared very light DC motor that had a rotor that had no iron core, it was more of a cup-like copper nest fixed in epoxy. Linear servos.
There should be more photos somewhere, probably on some back-up cd-roms. But those photos might inspire someone to build. You have my permission to use the photos for any purpose that might gain the hobby.
I am mainly control line flyer nowdays, but do some vintage/oldtimer freeflight and some modern classes freefligt (F1S, P30), Best regards,
Ingvar Nilsson - 17/01/2025
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