Sirocco (oz9086)

About this Plan

Sirocco. Free flight power model. Wing area 262 sq in. Plan also shows alternative extended wing giving 300 sq in area.

Quote: "Geodetic warp resisting structure, a tubular sheet fuselage and an obsession for altitude. Sirocco is no second-best, it screams high, transitions well. For a Cox Tee Dee .049.

The Sirocco design was developed around the current AMA rules requiring the decreased engine run for fly-off flights. Seeing contests come down to a 5 second engine run caused some thought to be given to the necessity of grabbing a good chunk of sky in a relatively few seconds.

A short run requires a super clean design. I have attempted to come up with a strong, lean and capable planform that is super stable and reasonably quick to build. The easy-to-build features may not be as quick and as simple as some profile square jobs, but, remember Rome wasn't built in a day. I build for enjoyment. I like the hours at the bench, so I feel why not spend a little more time and make it a worth-while project?

The small 265 square inch size makes for a fast, if not spectacular climb. This emphasis on altitude is very important to compete on those short engine run fly-off flights. With care you can build it and hold the weight to around six ounces.

For the first three flights in Category I (5 minute max contests), a slightly larger 300 square inch version is shown. The wing and stab are stretched out 6 in and 3 in respectively.

Construction Techniques. The fuselage is a little out of the ordinary, so let's start with its assembly. It is primarily a rolled tube of balsa. I turned my form on a lathe, but if a lathe is not convenient, you could carve a form or use a table leg and carve the forward portion only. Cut a balsa blank to fit the form. Soak the balsa in hot water and bend it around the form and wrap it tight with an 'Ace' elastic bandage until dry. It may then be removed and the seam of the roll-ed balsa cemented.

One piece of 1/16 sheet (medium grade) within the area from the back of the pylon forward may be reinforced with 1 oz. fibreglass cloth and two coats of resin. The engine mount itself is a 3/16 plywood tray cut and beveled to fit and glassed in place. I fitted the pylon in place with the fuselage up off the building board in my hand, but be careful to check alignment..."

Sirocco, Flying Models, January 1973.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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