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Written by Dilbert Grumpyman   
Tuesday, 17 March 2009 17:51

 

Radical RC Quick Wing 20mm

Trevor Barton


The Yorkshire Air Spectacular Christmas Model Show at Harrogate Pavilions is always a temptation, the site being only a few miles from home, and November 2008 was no exception. So, along I went, clutching my little wad of cash, seeking a bargain here and a bargain there, finding bargains just about everywhere and as usual I soon found myself approaching the end of my budget and wondering what to do with the last few quid.

All was not lost, though, when I came across a little display on the Micron stand which had a collection of plastic bags full of balsa bits, all for a pretty modest sum. They were kits from across the pond, Radical RC in Dayton, Ohio, none the less, a town that brings to my mind the Dayton Ohio Speedway, something of a legend from my childhood.

Well these models looked like they'd be something. The one that caught my eye promised to be something of a speedster itself, the Quick Wing 20. Not only fast in flight, but, with any luck, fast to build as well. So I handed over my last 26-quid note, and wandered off with the bag of bits in my coat pocket.

Fast forward to March 2009. As usual, life, work, Christmas, work, life, kids, dog, work and the rest got in the way, and the kit sat on my workbench for a few months. Then my deck cleared and all of a sudden I found myself with nothing much to do for a weekend! So, this is the story of what I did...

Opening the package revealed a number of sheets of laser-cut parts. Not your average cut parts, though. These were precision-cut parts. That's what the kit promised, anyway, and that's what I got.

Just look at the pictures below. You can click on each of them and they'll open in a new window in full-sized technicolour glory. The fit of the individual parts is exact - I didn't find anything in the whole kit that was the wrong size. Everything locks into place like a jigsaw. The picture below right shows the elevon inboard end stiffeners, once they're slotted into place they don't come out, and they're tightly held so you can just wick some runny CA into the joint and the job's done.

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There's a comprehensive set of instructions on 5 sides of A4 (well, I guess US letter size) and in lieu of a full-size plan there is a plan sheet, that is really a technical drawing of the plane as it goes together. Actually, "technical drawing" makes it sound far more technical than it really is, but it's heavily annotated to make it easy to identify all the parts and how they go together. As it says in the instruction, you really don't need a full-sized plan, because the balsa has been deliberately shaped and cut to ensure everything comes out square and straight. Of course, being an engineer I had to verify that myself but it certainly was the case, everything that was supposed to be straight was straight, and everything that was supposed to be square was square!

It's not a kit for the first-time builder, for sure, because the instructions do assume a bit of prior knowledge, but it's a very easy kit for someone that's got one or two previous under their belt. In fact, I found it difficult at times to suspend my disbelief and trust that it was going to work out square, but such is the precision of the cutting that there were no problems whatsoever.

The first thing to be done is to fit the stiffeners to the tips of the elevons and fins, and assemble the hatch and the top and bottom sheeting parts. The motor box sides are labelled T, B, L and R, and assembling them correctly gives the correct amount of side and downthrust to the motor - the text goes inside the box. Then the spar is glued together - it comes in three sections - as is the two-piece trailing edge and leading edge. Next the tabs on the front of the rear ribs are pushed through the spar, and glued to the trailing edge by wicking thin CA into the joints. Oh, and the bottom rear sheeting is glued into the centre of the wings, I guess to make absolutely sure that everything is nice and square for the later build. This is the last glue that's used for quite some time, now.


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Now the rest of the wing is assembled. This is where the jigsaw comes into its own. First, the wing tips are slotted onto the trailing edge. Then the filler ribs on the LE that have a tab through the spar are pushed into the spar, and the LE is fitted to them and pressed into place after fitting the two nose ribs and slotted into the wing tips. Then, the front parts of the rear ribs are assembled onto the LE. Finally the nacelle LE parts and brace and the motor box sides are all assembled onto the wing.

The whole contraption is now held together by the precision of the cutting. You can pick it up, turn it over, fling it around and put it back down again and nothing will move. It is absolutely superb.

Now's the time for the glue. just wick thin CA into all the joints, and you have a fully completed airframe just waiting its various sheetings and fittings.


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Now comes one of the only fiddly bits of the whole operation - the leading edge sheeting. Well I say fiddly, it's not that bad, but you do have to bevel the front of the sheets so that they're flat against the LE itself, and then soak the outer side of the skin so that it softens and swells a but so it's easy to bend. Not all that hard, but it is fiddly. If you're daft, like, me, you'll use thick CA and then stick your fingers to the skin when you hold it down while the CA cures. After the first of the four sides, you'll think of putting a sheet of cling film between the balsa and your fingers so it won't be so bad for the other three.

Once that's done, you have some idea of the final aeroplane.


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Finally, it's just a matter of building the servo boxes and outer sheeting on the tops, sanding the LE to shape and the trailing edges, bevelling the front of the elevons so they can pivot, mounting the air scoop on the nose along with a couple of nose rings to fill the gap between the firewall and the spinner, and sanding the nose to shape.

A final sand, and the airframe's ready to cover.


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Now these next pictures really don't do justice to the full horror of he colour scheme I chose. This is a small plane, and I expected it to be fast. It also doesn't have much of a profile to determine the orientation when it's screaming our of a 400' dive, so I decided to go for something - how can I put this - distinctive. And distinctive it is. Although that wasn't one of the words used by various members of my family and club!

The picture on the left best illustrates the colour of the top surface. The middle picture caused the poor camera to gag, and it lost all sense of white-balance, so the pinky-purple colour looks a marginally more acceptable reddish-purple, but, before you breath too much of a sigh of relief, don't. It really is worse than words or even pictures can possibly describe. Particularly when you contrast it with the bottom surface , which is pinky-purple at the front, and red and yellow checked on the wings.

Still, I won't go mixing it up with anyone else's model, will I?


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Finally, after taping the elevons, and installing the motor, servos and receiver it was ready for its maiden flight.  Don't do what I did, though, and underestimate the depth of the firewall and screw the motor mounting screwsa into the windings.  It'll mean buying another motor. 

Last Sunday was mostly sunny, but fairly cool, with a blustery 10-15 mph wind, but I wasn't going to let that deter me! After a bit of discussion about first flight launch techniques we decided on a flat throw, one hand on each wingtip, just to ensure it got away with no nasty twists or rolls. So, with Stephen doing the honours, the Quick Wing was cast into the heavens.

And into the heavens it went! Quick? Yep. Aerobatic? Yep. Vertical performance? Yep. Straight down from 400' and pull a tight bottom corner to level? Yep. Insane roll rate? Yep. After a few minutes of fun it occurred to me that it might be an idea to check the trim before I landed it. Once again, the precision build method showed its value. A click of left, a couple of clicks of right, and a final click of left to re-center the ailerons and all was OK. I think I might have put in a click or two of down, too, but I can't remember.

Landing was a doddle, even in the wind. It just sort of arrives. Actually, I hadn't set the brake on my speed controller, which leaves the prop spinning when the motor's throttled off, and that resulted in a broken prop after the second flight. Luckily I had a spare!


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Equipment and Specification

Motor 20mm Inrunner from Micron, 2900kV.  I'm not sure which motor it really is, because Micron don't show much information about it on their website, but I think it might be one of these.
Prop APC 4.1" x 4.1"
ESC EMax 18A
LiPo 1000mAh 3s.
Servos 2 x Hitec HS65-MG
Receiver Spektrum AR6100 2.4GHz
Weight 344g / 12oz with battery
Power 160W peak/145W constant on bench.  Approx 190-210W/lb.