Arup S2 ‘Heel Lift’ (42″)

(1 customer review)


A 42” span near scale ‘flying wing’ for .40-size engines and 4-function R/C. Designed by Keith Humber.

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Arup S2 'Heel Lift'

A 42” span near scale ‘flying wing’ for .40-size engines and 4-function R/C. Designed by Keith Humber.

Arup S2 'Heel Lift' - Laser Cut Wood Pack

Laser cut wood pack for this 42” span near scale ‘flying wing’ for .40-size engines and 4-function R/C. Designed by Keith Humber.

£65.50 £58.95
Arup S2 'Heel Lift' - Laser Cut Wood Pack

Plan and Laser cut wood pack for this 42” span near scale ‘flying wing’ for .40-size engines and 4-function R/C. Designed by Keith Humber.

SKU: GP-MW3399 Categories: , , ,

Full Description

Keith Humber’s near scale 42” span design of this 1933 ‘flying wing’ is powered by a 6.5 cc engine and 4-function R/C. Construction is all wood from the detailed 2-sheet plans. Flying characteristics are typical for this type and should be flown by experienced pilots only.

About the Full Size:

Design – The full size Arup S-2 featured a straight leading edge wing with a trailing edge that tapered to the rear of the aircraft giving it a guitar pick shape when viewed from above. An M6 airfoil was chosen over its predecessor’s sharp edged, modified Clark-Y airfoil. The large trailing edge control surfaces were mixed for pitch and roll control, but were assisted by small, movable, semi-circular wingtips that could provide additional roll control. Conventional landing gear was used, faired with wheel pants. The access to the cockpit was from a belly mounted hatch. Visibility was enhanced with celluloid panels on the aircraft’s belly.

Operational history – The prototype S-2 was test flown by Glen Doolittle. The STOL aircraft could fly at up to 35 degrees angle of attack without stalling. The aircraft was demonstrated across the country at events like the Indianapolis 500 and the 1933 National Air Races. Later it was demonstrated to the Army, NACA and CAA in Washington. D.C. Raoul Hoffman left Arup after the development of the S-2 to create his own design, the Hoffman Flying Wing. Engineer Charles H. Zimmerman viewed the S-2 trials in Washington and later applied the principles to the Vought XF5U program.

The S-2 was sold without an engine to a stuntman, F.F. Bowser Frakes, who performed air crashes at fairs. A Szekely radial engine removed from an American Eaglet was installed on the S-2, but did not perform well. A propeller was acquired from Milt Hatfield, who sourced the landing gear for the first S-1. Hatfield demonstrated how to fly the aircraft and it was eventually crashed in a show.

Images kindly supplied by Kenny Beggs and model builder Alastair Nicol

Plan MW3399 Wood Pack WP3399 Short Kit SET3399


  • Designer: Keith Humber
  • Wingspan: 42″ / 1067 mm
  • Power Source: IC Propeller
  • Radio Functions: 4
  • Scale: 1:5.42
  • Length: 38″ / 965 mm

1 review for Arup S2 ‘Heel Lift’ (42″)

  1. Jorgen Pedersen

    A great little model, but not an easy build
    The instructions suggest this is an easy assembly, I would tend to disagree. The instructions suggest building the wing upright (vertically) balancing the wing ribs on the leading edge, with the ribs sticking upwards. This may be possible if you knew the centerline of each rib – but unfortunately that is not provided. An alternative approach would be to supply tabs on the ribs to build it horizontally, but again none are provided. I opted to build it horizontally, by adding my own tabs to the ribs, which worked well. The second issue is the suggestion of bending balsa around really tight curves to form the wing spars, I tried multiple times, ended up distorting the wing profile and snapping he balsa. So I opted to add separate balsa parts and then sand them to the right profile – much simpler and significantly less stress on the wing. The third issue is adding the trailing edges, which again has significant curves, after two attempts I got this done, but have now noticed a warp in one of them so will have to cut off this section and redo. Again this could be done much easier by having a laser cut shaped Trailing edge notched into the wing ribs.
    From the size of the servo’s I suspect this is an older design, it calls for servos to be mounted to 2x snake connectors which go through the wing and poke out underneath the wingtip ailerons. I have opted to add two smaller servos mounted in the wing tips which directly connect with the ailerons.
    The scale machine had full moving wingtip controls, on this model for stability reasons they have been changed to fixed leading edges with trailing edge ailerons. I couldn’t bring myself to deviate from the scale machine so opted to put fully movable ailerons, – which may end up being my nemesis.
    This is not a bad plan, and it does look pretty neat, but it is not a simple build, and probably requires someone who has done this a few times before.

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