Split Tweety

[Split Tweety]I'd been eyeing the Split 280 kit at Aeromicro for ages.  It had two big points going for it: it's made entirely of EPP foam, so it's very rugged (its nickname turns out to be "Boink-Zoom"), and it's a very easy build, with the wing and fuselage already made.  Also it's small (29" wingspan) and relatively inexpensive.

But I was hesitant.  It's billed as being basically a pylon racer: go fast, turn left (or right).  I like planes that are fully aerobatic, and I want to get better at aerobatics, with a plane that's not so delicate that I have to worry about it all the time (like I do with the Hornet, or the Edge, or the Triangle).  And I was really sick of building planes, really easy ones.  While I was learning to fly I had to sacrifice all my spare time to building and repairing planes, and I was sick of it.

Dave saw me eyeing the Split, though, and it got him to thinking.  He has no such hesitation about building planes; he's so obsessed that he needs a new plane to work on all the time.  So he took the plunge and bought the kit.


He couldn't just throw it together as specified in the kit, of course.   The supplied tail surfaces and ailerons are coroplast (for ruggedness), and Dave loathes coroplast (because it's heavy), so he built a balsa horizontal and vertical stabilizer, and depron foam control surfaces (including rudder, though the kit is designed to be aileron/elevator only).  The EPP wing is extremely flexy, so he put a thin carbon fiber spar through the bottom of the wing, and another along the fuselage.  But the biggest change he made, as a born-again brushless outrunner motor convert, was to replace the supplied 280 direct drive motor with a Tweety brushless outrunner (so it's not a Split 280 any more, it's a Split Tweety).  Naturally, it took him a while to get it all together, compared with the couple-hour predicted building time for the stock kit.

[Split Tweety, first launch]The trickiest point was getting anything to stick to the EPP.  This EPP, unlike the lighter kind used in planes like the Weasel and PCW, resists most glues.  Shoe Goo won't stick to it at all.  Neither will packing tape, and even Probond doesn't do too well.  This left a dilemma about how to hinge the ailerons.  Dave eventually decided to try GWS glue on the EPP, then tape stuck to the GWS glue.  This seems to work -- so far.

Dave couldn't stop talking about the Split after his first outing with it.  It was wonderful, it was the best plane he had ever flown, it was everything he'd been looking for.  I finally gave up and got one of my own.  I put in a thicker spar than he had (a CF tube rather than just a thin rod), which added a few grams but made my wing quite a bit stiffer than his (we'd both noticed that his wing bends noticably under load while flying).  I didn't put in a fuselage stiffener.  I ran my rudder control rod along the bottom of the fuselage, next to the elevator rod, and I ran a wire from my rudder down through the middle of the elevator rather than split the elevator and run the rudder between the two elevator halves.  (I don't recommend this, however; it took me forever to get the rudder linkage working right, whereas it's really not that hard to join two pieces of elevator with a u-bent wire.  If I have to do any further work on the tail surfaces, I'll probably rebuild them that way.)  My ailerons are a bit bigger than Dave's (patterned after the Hornet's because I had a couple extra Hornet ailerons sitting around, and because I figure a little more wing surface never hurt anyone) and I put some markings on the bottom because with Dave's I had a really hard time telling when it was inverted.  (I still have trouble with mine, since the red stripes show through the yellow depron ailerons, but it's better than nothing.)

The only hard thing about the build, really, is routing the servo cables through the fuselage and wing to the receivers (which we both put under the canopy -- not where the instructions say to put it, but things are pretty cramped under the fuselage).  I originally wanted to build my Split with the supplied 280 motor, just to see how it worked, then upgrade to a Tweety or other brushless later.  But my Tweety arrived on Friday instead of Monday when I expected it, and routing the wire from the speed controller to the receiver turned out to be such a hassle that I decided I didn't want to do it any more times than necessary.  So I installed the Tweety and still can't comment on how well it flies with the stock engine.  Probably okay, though I can't imagine it would be very fast or anywhere near as aerobatic.


[Split Tweety on final approach]Dave is right.  This plane flies great, and it's as aerobatic as anything else I've flown.  It flies inverted just as well as it flies rightside up, it rolls, loops inside and outside, and spins just great.  It's currently my favorite plane.

The Tweety motor was amazing, too: with a 2-cell lithium pack, it's sedate yet has plenty of juice to power the plane; with a 3-cell and a slightly smaller prop, it turns into a rocket motor which can take the plane straight up, or do torque rolls or lomcevaks (neither Dave nor I know how to do this yet, but we've semi-accidentally managed it a few times, enough to see that the plane is capable even if the pilots aren't).  It can probably hover, too, but we're still working on learning how.  My current goal is a flat spin, which I haven't managed in any plane, but the Split has come much closer to it than any of the others.  (I'm not sure why the Hornet won't flat spin; maybe not enough rudder, or maybe the drag of those big thick wings fights a flat spin.)


[Boink-Zoom!]And yeah, boink-zoom is right.  A few hard landings didn't hurt the plane, though eventually the bits around the nose on either side of the motor did break off.  The instructions (written in charmingly poor English -- the plane is Czech) suggest dogfighting two Splits, which sounds like a fine idea that we'll have to try some time when we're not too busy having fun doing aerobatics and learning to hover.

It does break props a lot, though.  The plane is tough, but the prop is the lowest thing on it and since there are no wheels, even a gentle landing can bend or break the prop if it happens to be vertical at the wrong time.  I added a set of wheels, which helps quite a bit.

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