Miss Charlotte (oz10006)

About this Plan

Miss Charlotte. Free flight model for .5 to 1.0 cc diesel engines. Low wing design, with wing slots for stability.

Quote: "Meet Andy Brough's charming Mayfly Trophy contender.

After writing the promotional article for the 'Mayfly' trophy, published in the January issue, I was taken aback when your editor asked me to design a model especially for the event. I protested that I'd never designed a F/F model let alone one that specifically couldn't be a high wing cabin type! However I soon came round and decided to have a go at a low wing design, which was the type I had in mind to build anyway, albeit a proven Vic Smeed design.

Design process. As the plan was to be a 'freebie' this dictated the approximate size plus the fact that the event is scheduled for Old Warden where smaller free flight models are to be preferred. The second influence was motive power. With so many Mills 0.75s around these days it's possible to offer plans that use these motors, the bearer spacing being wider than more modern designs such as AE and PAW. In fact the Mills bearer spacing will also accommodate many popular old diesels including ED Bee, Allbon Spitfire and AMCO .87s.

For those of us who collect or accumulate old motors it's often the desire to put a particular motor to use rather than the other way round. That of finding a suitable motor for a model. This was true in my case is I had recently bought a good example of that famous beginners' motor, the ED Cadet - known for not removing the skins off rice puddings! The almost new motor was bought for £10 from a model shop who had accepted it in part exchange, (as an ED Bee!) for a modern glow motor. The power and running characteristics are perfect for slow flying free flight models and with very conservative porting complete with a silencer, the Cadet is perfect for our purposes. I've seen Cadets at swap meets but never in a model, so my mind was made up.

At this point I now had the basic plot. A small low wing model with around 0.75cc power but before the first sketch was made one important feature sprang to mind. A model intended for precision flying, as required for the Mayfly, should be made to fly in quite small circles, both for power and glide. So to make sure it would be stable I decided on wing slots. This is a feature seldom seen on any models and possibly not on a published free flight design since PE Norman's famous Natsneez (oz2251). I can vouch for the stability of that design so I had no hesitation.

The wingspan was fixed at 38 in and a projected all up weight of just under 1 lb. A precision model doesn't want to be too much of a floater otherwise it would be less predictable and prone to catching thermals! Aesthetically I wanted to emulate a light plan of the late 20's / early 30's so all that was left was to make a few sketches and draw the plan. For the first time I went into the workshop and built a model according to the plan! The name? Oh, it's who we call the Brough junior fetcher mite! Actually very good at launching too.

Construction. Wing. The first item to build is the wing so that the exact profile for the fuselage cutout can be obtained later. The construction is simple and I started by cutting out the tip sections followed by the ribs, the outer ones being left full size until the outline of the tip is pinned down. These can then be trimmed to the actual size so they are a good fit. The centre panel has the outer ribs vertical and the outer panels have their outer ribs set to the dihedral angle with the template.

The construction of the slots is dead easy. Glue the riblets to the appropriate ribs and using white glue attach the 1/32 sheeting. Use a new blade in your balsa knife and score through the sheeting at the rib positions so that it will pass between the ribs. Add the 1/8 square strip underside to reinforce the edge. Add the top and bottom sections and carve and sand to the wing profile. Complete all panels with sheeting and cap strips and sand before considering joining. Take a good deal of care when sanding the ends of the panels. Use a sanding block, not loose sandpaper. Cut out the piece of rib between the spars and check the fit of the dihedral brace. Assemble the whole wing dry and check the mating ribs are flush..."

Scan from DBHL, cleanup by theshadow.

ref DBHL-6882.

Direct submission to Outerzone.

Supplementary file notes

Article thanks to Algy2.

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