Foamie Design Challenge

 

The challenge was to design and build an indoor, rubber powered foam model, and was flown at the February 2023 meeting at Begbroke.  A basic ‘kit of materials’ was made available with a ready-made propeller assembly included and 9 modellers took up the challenge to produce a model. A light hearted flying event took place with the models and the winners of the various classes decided by our noble judge Andy Blackburn

Models designed ranged from simple stick models through to high wind monoplanes with built up fuselage and even a biplane. All flew, some to better effect than others but the fun factor was very high and made for a very enjoyable competition

 

Most artistic model     Simon Burch – Mach 2 FROG Interceptor

Most exciting flight    Simon Burch

Most stylish take-off   Chris Brainwood – SE5a Skywriter

Most imaginative abuse of the rules  Alan Trinder (No wheels) – Foamy Stick

Most aesthetically challenged (model!)    Duncan Martin (sorry Duncan!) – Foamy Stick

Best attempt at bribing the judge (offered a biscuit)   David & Jasmine Phillingham ‘Flying Postcard’

Best attempt at sabotage of other people’s models     David & Jasmine Phillingham (at least 10 model strikes between them)

Models entered in the Foamy Design Challenge

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The Rules

  • The model is to be made primarily from 2mm wallpaper foam. Other materials can be used in small quantities for such things as spars and local reinforcing.  You don’t have to use all of the items in the kit.
  • Max wing span, 13 inches, wingtip to wingtip.
  • If it’s a powered design, you must use the 4.7″ prop assembly supplied with the kit
  • Excepting gliders, models must have at least one wheel, made using the 1″ Depron discs supplied. Although not mandatory, the judges will be impressed by a unassisted take off from the ground. 

The ‘kit’ will consist of:

  • Piece of 2mm wallpaper foam(50cm by 50cm) – more available on request if you need it.
  • Propeller assembly (if required) 4.7″ diameter
  • Length of 90 thou rubber. Other sizes of rubber will be available on the night
  • Small length of 20 swg tubing for the rear motor peg
  • Small piece of 3/32” balsa for a noseblock & nose plug (this can be substituted with any other size of balsa, as you wish)
  • 9″of 22 swg wire for the undercarriage and two small lengths of tubing for wheel bearings
  • Four discs of 1mm Depron for the wheels. Glue two discs together, with a short length of tubing for the axle bearing
  • Copy of an article from Aeromodeller on building with wallpaper foam (by kind permission of Aeromodeller)

Hints :-

  •  Maybe choose your favourite kit design (Ajax, Ace, Senator etc) as the basis for your model? 
  •  Or design a simplified scale or semi-scale model that ‘looks a bit like a…’. Use any three-view We’d suggest enlarging the fin and tailplane areas by 25-30% for greater stability. 
  •  Set the wing incidence at about 3 degrees relative to the tailplane and the balance point at about 1/3 of the wing chord. Adjust this with ballast (BluTack) for a good glide. 
  • Give it a reasonable amount of dihedral – at least 26 mm for a low-winger, and 8 mm for a high-winger (assuming a 13 inch span). 
  •  Remember that for stretch winding, the nose block will need to be removable with a plug to fit the front of the fuselage. 
  • Most people will have PVA already, which works well but has no ‘grab’ so you would need to tape the parts together while it dries. It has the advantage is that you can reposition the parts. Alternatively use UHU POR (readily available – Amazon sell it) as a contact adhesive. Smear a small amount on both surfaces, leave for a few minutes then bring the parts together for an instant joint. NOTE: there is then no chance of repositioning! Use very tiny amounts of epoxy if necessary but on no account use cyano, unless it is “foam safe”. 
  •  The formula for success is to choose something with sensible proportions, i.e., lots of wing area and to make it light. Aim for about 9-12 grams. 
  • The categories for judging will be decided on the night in the normal light hearted manner and the prizes will be consumable as is now the tradition. 

Foamie How-Tos

Click the link for PDF

  • Shaping corners of Wallfoam – Andy Blackburn

The secrets are a) sand it wet/damp, b) use a curved sanding block as shown. Do not sand it dry as the dust can be dangerous to health

Another tip worth adding is that UHU Por is easily and safely removed, and joints made with it  “unmade”, by application of common-or-garden lighter fluid

  • Foamy Challenge Over-Production – David Lovegrove
 
Here at Lugole Towers, the past few freezing days have stimulated a rash of wallfoam-model-madness! Attached is a photo of the four models I’ve knocked out this week. Unfortunately, only two of them fall within the confines of Bob’s Rules, but I enjoyed making them anyway.
 
From left to right,
 
1. a 75% version of Albert Platt’s “Shadow” delta, published in the Aeromodeller some twenty-odd years ago. He was an OMFC member but dropped out of the scene after the design was published.
2. A rubber-powered version of my O/D “Stik-R” lightweight indoor model (3.2grs). Qualifies.
3. A new build of my “Wot Ho” indoor rubber-powered design from the last century! Also qualifies.
4. Finally, a super-capacitor/electric-powered version of the “Stik-R”, this one called the “Stik-E”. Geddit?
 
A good idea Bob, your Foamy Challenge. I’ll bring these along on Wednesday to show our people the possibilities.
 
 
 

 

 

 

Have fun !