David’s new glider design, the ‘Mediator’

By | November 10, 2020

Back in ‘71/72, we used to fly control line models for three hours every Sunday morning in a field next to The Rowdens at the top of Eastcliff Lane in Teignmouth. Not a silencer in sight. How the neighbours stood the noise I will never know. As far as combat flying and aerobatics were concerned, the model that really stands out in my memory was the ‘Peacemaker’ designed by George Aldrich. Wow. What a great flyer that was! A legend in its own lunchtime. Not many 50 year old designs have their own Facebook page! https://www.facebook.com/George-Aldrich-Peacemaker-411836712594945/ Maybe I could I create a slope soaring version of the Peacemaker?

Control line model the ‘Peacemaker’

Whilst researching a previous creation, I accidentally came across VTPR high performance aerobatic gliders (VTPR is French for “aerobatics very close to the ground”). If you’ve not seen it before take a look at this  https://www.youtube.com/watch?v=_oBuqhEg0xU. I was amazed(!) and set myself the task of creating a new design that combined three things; the shape of a Peacemaker, some of the principals of  VTPR design, and my own ideas.

I stretched the Peacemaker’s wing-shape spanwise but kept the aspect ratio still quite low at 1:6.5 rather than 1:4.3. Used a completely different wing structure and airfoil – semi-symetrical SBV96V at the root and symmetrical at the tips – and made the ailerons pretty huge (as per VTPR). I retained the characteristic Peacemaker wing tips and tailplane shape but moved the elevator hinge line forward which dramatically increased the elevator size. I designed the fuselage profile pretty much from scratch. Its wing position is as per VTPR and its canopy and fin shape reminiscent of the Peacemaker but that’s where the similarity ends. I played around with it for ages. The “if it looks right it is right” theory only works if it actually does look right. In the end I’m very happy indeed with its nice curvy outline.

Rubber banded wings are great – delightfully simple and very forgiving in crash – but not so easy with a mid-wing design. After much head scratching I came up with a simple three-piece design. The one piece 54” wing will be banded onto the lower half of the fuse and then the top half of the fuse will be banded over it. Two of the servos will be in the wings – that’s a first for me – which means the fuselage can be unusually narrow (another VTPR design feature) which apparently aids knife edge flying, not that I’m capable of doing it(!) but at least the model might be. So here’s my Plan for the ‘Mediator’…

One thought on “David’s new glider design, the ‘Mediator’

  1. John Harvey

    Hi David, apologies ,meant to post a comment on this design some time ago….you know, this and that came up!
    No one could doubt your enthusiasm for design and build, you must be useing up your balsa scraps by now. I am trying to be very careful how I cut wood so as not to create lots of unusable off cuts. It’s good to see something on the board that looks different. So many non scale gliders are very similar, using tried and tested arrangements of wing , tail and fuselage design…bit like modern cars. VTPR sounds like a dangerous activity, I’m guessing speed and a steady thumb and finger will be an advantage, just get her flying first! My K7 will weigh circa 10kg at an estimate and Felix’s tug will cope perfectly well especially as the K7s wheel will reduce any launch friction/drag (better make sure it goes round)
    Anyway David well done on the design stage of the Mediator, look fwd to build pics. Have to say though I am a little worried about your enjoyment of ‘nice curvy outlines’ and ‘rubber’
    All the best
    John

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