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Rapier-powered Yak 25 M "Flashlight" by Steve Bage
Steve is a recent convert to the joys of free flight scale jets, and believe it or not this beautiful model is his
first attempt at designing a model for Rapier power. Steve is a skilled CAD draughtsman, and the quality of the plan speaks for itself.
First flights of the prototype took place in March 2005 using 110 mN rated L2 motors, and were a complete success. Here are a few words from Steve about the flight trials:
"It was such a nice day here in Aberdeen that I took a half day holiday and
gave the Yak its first flight. I'm amazed to say that it flies better than
my wildest expectations. The first flight showed a slight stall but it still
gained a great deal of height before the motors expired, followed by a
semi-stalled 'mushy' decent to earth. I removed the tail weight (blob of Blu-Tac on photo above) and gave it
another go... this time it climbed away straight as an arrow... too straight
in fact. It flew right out of the field and into an adjacent marshy/bog
area. After yomping though the bog I eventually found the plane had come to
rest in a big gorse bush, fortunately the only damage to the plane was a
slight ding in the leading edge and a couple of minor punctures in the
I gave it another two flights managing to get a consistent gentle
left turn trimmed into it on the final flight. All 4 flights were longer in
duration than anything I've achieved so far with my Sukhoi, so to say I'm
pleased is an understatement. It's also very stable which leads me to
thinking that scale Anhedral could be built into the model without adverse
effect, but I'll leave that to someone else.
The only tricky aspect of the flight performance is that it proved difficult
to trim a consistent turn. I think this is most likely due to the variations
in thrust between the motors resulting in first a gentle turn one way, then
the other, then straight as a die... it's a model for big fields!"
To read and print the pdf file you need Adobe Acrobat Reader, which
is a free download from www.adobe.com
Steve drew the original plan on A3 sheets, and if your printer can cope with the larger
paper size, this would be the recommended route. He has also managed to chop up the plan to fit on A4 sheets, though this was a bit of a
squeeze due to the extra margins.
The plan should print off full size if you set your printer settings to A4 paper, even if it has got different
sized paper in the printer. If in doubt, check against the mm scales on the plan sheets.
here to download A4 pdf file (400 KB)
here to download A3 pdf file (400 KB)