About this Plan
Sprinkle. Free flight contest model for .020 power. Wing area 160 sq in.
Quote: "If the name of this fine little 1/4A Free Flight plane intrigues you as it did
ourselves, we won't help you here but suggest that you read the text as it is a very fitting one that only the Simpson twins would dream up!
Our little bomb was not developed as an answer to a particular design problem, nor as the progression of an existing .020 design. It just came about during a winter of normal 'get-ready-for-next-year' type of building.
My 1/2A 'Tornado' had been flying since 1970; a new advanced 1/2A design 'Twister' had been doing well since 1972, and I had just finished drawing up a 450 sq in Twister for .15-23's, when my brother Roger walked into the garage. Viewing the new Twister development with a note of humor he commented on its name: Next will be a big 'B' job, you can call it your 'Cyclone;' then a huge 'C' job called a 'Typhoon', and if you ever get the notion to build a .020 size, you can call it a 'Sprinkle.'
So when our club decided to feature a 1/4A event at one of our monthly contests I promptly decided to field an entry called Sprinkle. A couple of nights later a 160 square inch bomb patterned after my other rear-finned designs was ready for building. A little deliberation on wood sizes, and Roger tore into his Sprinkle with gusto, while I sat back and kibitzed from a safe distance, slowly building mine amist a pile of sheeted FAI wings.
Two weeks later Roger was testing his Sprinkle; shortly after that, prior to the contest date, two more Sprinkles were finished by myself and an old Air Force team buddy, Gene Comontofski. Both of these Sprinkles were pre-trimmed prior to flying by adding 1/16 incidence to the trailing edge of the stab and a hair of right rudder. These adjustments were the same as were made to Roger's Sprinkle and proved to be all that was required on ours. The contest results? First and third at the first, and first and second at the next.
One outstanding feature of this little bird is its stability under varying weather conditions. It will VTO and hold a great nose-high power pattern in winds up to 15 mph. This was shown at the first contest where it hung three maxes in less than 45 minutes, all with a good Texas wind doing its thing. Sprinkle has been flown in regular 1/2A competition and has held its own under the present Category II rules. In most cases it will outglide normal QA's in the shorter engine run flyoffs.
One of our flying fields is so small that we hold mini-Category II contests, with eight second hand launches and ten second VTO's, with two minute maxes. Under these conditions the Sprinkles really shine. So if it's low cost, short building time and high performance you're looking for, let's start building.
CONSTRUCTION: Stabilizer: Select the lightest possible wood for these tail feathers; cut with care, handle with care and cover with caution. I pin my small stab down while water shrinking, elevating it above a wax paper surface by using 1/4 balsa blocks at all four corners and center of stab at leading and trailing edges. Let stab dry in this position for 24 hours so that the wood frame dries completely. Apply one thin coat of dope, any tissue trim, then finish off with two more thin coats. When dry to the touch, pin down for a few days to cure flat..."
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