The Accidental Weblog

We really do seem to have started a trend.

‘Kay. So I don’t technically know if maybe there was someone before us. But the last time (some three weeks back now, I think) we were flying rockets down at the park south of us where we started some years back, some minutes into our series of launches, there was another group next to us, also launching.

… and today, another nice sunny day in Ottawa, when I was driving past the same park on an errand, I heard that unmistakable hiss of a small engine, looked, and saw yet another party of rocket people sending one up, then kids chasing it down.

I should charge the local hobby shops commission. But seriously, it is nice to see people out, sending things skyward.

So one of the beautiful things about the modern world, for those of us practicing crashing remote-control aircraft is: you can do your first crashes on virtual remote control aircraft.

It’s really a lot cheaper. Compare and contrast: on the real field, with the actual, physical model, you screw up the landing, days or weeks may follow of rebuilding broken bits of balsa and Monokote, pulling the engine apart, removing any grit that might screw up the rotor in the carburetor or scratch the cylinder walls, and so on. Depending a bit on how hard you hit the ground and where. Oh, and also, the cost may be anywhere from a few cents worth of glue (very lucky) or several hundred dollars worth of engine (less lucky).

Whereas on the virtual one, you press the big red button, the model magically reassembles itself, and you are immediately ready to crash it yet again. No glue nor engine rebuilds required.

So much more efficient. And you can crash so many more models, so quickly and effectively. Go through a John McCain navy career* worth of splintered fuselages and engines, all in half an afternoon. And you don’t even have to refuel or recharge, on, y’know, the rare occasions when you don’t actually crash.

And they’re pretty good programs, generally. Not quite the same as flying the real thing, no, but they do get your thumbs used to the controls in a much lower-risk and lower-cost environment than the real flying field, at the very least. And a lot of how real planes really move really is in there. Wing stalls can happen. If your engine cuts out (or you cut it out on purpose for practice) the nose will drop as fast as the real-world plane equivalent would do. And you’ll have to work just as hard to set up and maintain a clean, airspeed-conserving glide path to get the thing back on the virtual ground as you would in the real world. Do thirty hours on a simulator, and yes, you are very likely to find the real things a lot less intimidating, very likely to have the reflexes you need to avoid costly non-landings at least partly developed, anyway… And, again, for vastly less expense and risk than is likely to be incurred keeping a real plane in the air 30 hours.

But while lovely (I do own one), the closed-source commercial simulators tend to suffer from the usual problems of such software, as against the tastes of digital tinkerers such as myself. Such as: they don’t run on Linux, and are annoyingly difficult to customize. And when really the only (apart from work) Windows machine you run really isn’t much of a powerhouse, this also adds up to relatively slow, jerky simulations…

So wouldn’t it be lovely to have an open source R/C flight simulator that did the flight dynamics just as realistically? One in which if, say, you want a plane of a particular style to practice with, you can just build one in open-source 3D modelers and specify its flight dynamics in an .xml file and away you go? One which works with your radio and/or the interlink box you got with the commercial sim you already own? One which I can put on my rather more formidable Debian boxes and let loose?

It would be lovely. And it is lovely. For there is such a thing. The open source CRRCSim just happens to do all of that, and, tho’ a little bit less blessed with eye candy in the base install than its commercial cousins, so far as I can tell, even seems to be a little smarter about doing believable variable wind than is the closed source sim I own. Developed mostly by R/C glider enthusiasts, this is a sim that takes wind seriously, and gets it right.

And yes, true, since it’s a bit glider-centric, the powered model selection is also a bit lean in the base install. There’s an ‘aerobatics trainer’, but it’s pretty flighty, pretty feisty, a bit of a handful, especially if you’ve nearly-first timers not yet into adolescence trying to nail their first landings on the thing… Breathe on the aileron stick, it’s pretty much corkscrewing wildly through the air, yeah, true enough. One of those planes. Traumatizingly realistic, even.

But then, since all you have to do to set up a more mild-mannered trainer more suited to absolute beginners just trying to get back to the ground in one piece is break out the 3D modelers, sketch one in the air and mess around with an .xml file to specify its various flight characteristics, this is less of a problem than you might think. If, y’know, you’re comfortable messing around with 3D modelers.

… so I have done so. Built this huge orange and white monstrosity that floats back to the runway roughly as aggressively as a hot air balloon. And introduced it to my budding flyers. And posted it online, for anyone else who might need such a thing. All in the spirit of open source, fairly enough.

So here’s to CRRCSim. A great little bit of ‘ware in which to repeatedly demolish virtual planes.

(More behind that: yes, I’m flying again this year. Or, more accurately, I’m more likely to be ground crew, most of the time, since the kids are both asking to do some more serious training this year, so my pretty OS Engines .46 AX is going to be busy in the trainer they’re going to be learning in. Not sure if I’m going to set up a plane more to my current skills… Do have other things I think I might want to be doing with the sunny days I’m not on such duties… Guess we’ll see.)

So on my lunch, I took a break from the real world of stuff I do so they pay me, and did a few more minutes on a teardown of a small, 2-stroke engine I’m working on in bits and starts, toward replacing the bearings. My kids are asking to learn to fly this year, and it looks like all is green administratively, finally, to getting that going. So I need said machine purring like a kitten for their trainer.

Unasked-for recommendation to all persons like me whose work is extremely not physical by nature*: do something like this, now and then. Metal in your hands and oil on your fingers is grounding, in its way.

Also, those engines are really very neat little things. There is this geometric beauty about them, especially the carefully ground and polished curves of the interior.

(/End channeling R. Pirsig)

(*/And never mind that, technically, I architect hardware. As it’s not like I ever actually touch the stuff myself.)

The long weekend (so far) was mostly cleaning. And after I got my desk cleared to the point that it became practical, some repair.

As it’s warm enough ‘round here to be launching small missiles with the kids again. And our space program ‘round here has a pretty busy launch schedule. And constantly launching extremely light vehicles mostly of balsa and cardboard, they do take a beating. Taking stock yesterday, after cleaning, I realized I had more than a dozen rockets in here—only two of which were actually in flyable condition.

Missing and broken fins, mostly. So, between other things, yesterday, I made a point of coming back to the study regularly, cutting a new one out of balsa stock, gluing the one previous to that on, painting the one before that, lacquering the one before that… Little bits of ten-minutes-at-a-time stuff on a long, messy reassembly line.

I now have twelve launchable rockets in here. We are back at fighting strength again.

Did another wings test this eve, at another club, over off the east end of the city. Had got to thinking having another field to fly from might have its advantages. It went okay; I got my signoff; can now fly there solo.

But honestly, the first landing was… bouncy. Had some throttle trim issues. Wound up bringing it down with a few more RPMs than I’d normally have liked. Climbed like half a meter out of the first touch, had to do a second, and with a little less runway than I’d have liked. Still pulled that off smoothly, dropped into the second one real nice, engine still running, taxied back. The guy marking me is watching, saying ‘Man, that thing comes down hot.’

… which sure, it had. But then I trimmed it out a little smarter, managed a much smoother, proper version. Fly it to the ground, taxi back, turn it off, all good.

My dead stick was memorable, tho’, too, this I’ll say. Slipped over the tall grass at the edge of the runway with very, very little to spare. Like tens of centimetres. And not many of those. And came to a dead stop, I swear, mebbe a meter from touchdown, mebbe three of those at most from the edge of the strip. Tho’ clean, soft, no damage, no real drama.

Hairy as it sounds, it’s mostly just what you get when you really don’t know the field, don’t so much have a sense of how far away stuff is yet. I’d burned more altitude earlier than was wise, had to glide flatter longer than I’d intended just to pull that off…

Still, it was also about the field just not being anything like the white knuckle inducer I’m used to. In the west end, there’s that nasty pit to disappear into, all those bouncy little updrafts, those crosswinds that just don’t quit. You get this healthy paranoia, after a while.

Out here, this was nothing like that. It’s yer classic mown strip in a huge, open field. You can see everything, imagine that. And the wind’s mebbe twenty degrees at most from dead down the runway, imagine that…

So even as the thing’s skimming over the top of the tall grass, I’m thinkin’: hell, even if it doesn’t make it, big fucking deal. So it drags into the grass, I have to mebbe fix up some rips in the covering, at worst. That, I can handle. There’s no deep, dark hole with, potentially, water in the bottom for it to smack into. Fine with me.

So it’s one confirmation, anyway, of somethin’ they’d told me early on in the west end: learn to fly here, nothing else is likely to scare you much for a while, anyway. This place is the stress test. It’s downhill from here.

True so far. Further updates as events warrant.

Seven solo flights the other day, all in very turbulent conditions, all on the trainer (a modestly modified full-sized Nexstar pulled by an OS Engines .46 AX*). Worked on low passes, landings, as these are a proper challenge across gusty cross winds. And you kinda need to be able to do this, to be able to fly there.

Landed ‘em all. Stalled the prop a few times, bounced a few times before getting it to settle, but no damage. Brought some down very smoothly indeed.

Had the skies to myself a few times, too. Wind seemed to be chasing people off. Go fig.

Re the Surfin’ Bird: I moved to a 10x6 prop, as per previous. And between that and the fact that someone had cut the grass on the runway, it was all good. I had lots of thrust for takeoff…

… which, on this thing, is a surreally gentle experience, once you get the notion. ‘Liftoff’ ain’t really the word. It’s more ‘driftup’. Thing just sorta floats into the sky, like it’s arbitrarily decided now would be a good time to start ignoring gravity. It’s got a hilariously short takeoff distance, too, but not because it gets up to some roaring speed fast. Rather, it’s because the thing can take off with so little airspeed. You get it rolling, point it into the wind, tap the elevator, and that’s it: up we go. A couple seconds rolling forward with the throttle up near max, and it’s off the ground.

Took three tries to get that, tho’, incidentally. First two, I tried too hard, pulled up a little too hard, as it lifted. You don’t want to do that with this thing. Wing stalls are merciless, when you’re already at such an incredibly low airspeed, and can’t just grab more fast by pounding the throttle forward. But it was no biggy—couple little aborts like that, couple engine restarts, and on the third, I got it: pull gently, let it rise in a shallow angle. Concept to grasp: it’s in no hurry. So you can’t be either.

The flying speed, too, is bizarrely slow. Again, its like there’s something antigravity about the thing. You’re looking at the size of it, and it’s just sorta hanging there in the air, lifted on the tiniest gusts. Doesn’t seem quite like it should be possible. And honestly, you can’t make it go fast. At full throttle, it rises, but hardly aggressively.

Fluttery, too, tho’. Flighty. Does these strange little spins and dives, and with not much warning. Not sure what gives there. Was fiddling a bit with power, trying to figure out what it liked, how to keep it level, and honestly, I never quite nailed that. It was always climbing or descending. There’s generally a lot of turbulence at our field—ground effects from a lot of relief—dunno if I can blame that here, or if something else was at play. But it seems plausible. Thing needs so little lift, reacts so quickly to it; the tiniest shadow of a thermal, a gust up the side of the pit next to the runway, that’s probably all it takes.

Between that and the sense of having so little power at your disposal, honestly, it was a little nerve-wracking flying it, this first time out. I’d got an incredibly still evening, figured that was my best shot, but the thing is, with every little gust I was always thinking: damn, can I even bring it back from there? Does it even have the thrust if I have to pull it upwind to here?

This was probably more perception. I’ve been flying stupidly overpowered planes ‘til now, spoiled that way.

Crashed it, coming back, sadly, tho’. Not terribly: have some glue work to do between the horizontal stabilizer and the fuselage, and on the forward wing stop thing, and given maybe two hours of such stuff and some covering repair, it should be ready to go up again. And the landing gear did snap off, very cleanly, at the nylon bolts. That, at least, went according to plan.

It was one of those weird little flutters—I was bringing it down, trying to angle back to the runway, after some ten minutes aloft. And something kicked it over (I want to blame some updraft up the side of the pit again—it is this or cop to my own thumbs doing something stupid) a little shy of the runway. Didn’t have airspeed to recover; spiralled into the ground.

Anyway, still: I call this success. It has flown, albeit briefly. So I figure: clean it up again, fix the broken bits, let’s try again. So I’m getting somewhere, here, anyway.

Just updating re the Surfin’ Bird/Butterfly/motor glider thing: it has yet to become airborne.

This isn’t for lack of trying. I made my first attempt this eve in iffy conditions—30 kph gusts, lulls almost still, figured I could probably handle it. The odd bout of 30 kph, I can certainly now do with other planes, anyway…

Sadly, however, it looks like the engine/prop combo I had mounted for said attempt apparently lacks the oomph to taxi through grass fast enough to lift off. In fact, alarmingly, the .30 FS and the 10x4 it’s currently swinging can’t even pull the thing out of the grass if it gets stuck a certain way. And I hadn’t even brought a prop with higher pitch because I’d seriously been thinking that, if anything, I was gonna wind up with airspeed to burn with the .30. The thing sometimes flies on a .10 two stroke, after all.

Still, this isn’t, for the record, wildly alarming or anything. The thing isn’t really designed for ground takeoffs in the first place, and it’s understood the tiny engine is just supposed to have the wherewithal pull it airborne. And the 10x4 was the lowest pitch recommended for the .30…

Sooo: I’ll be trying again in a bit with a 10x6. And hopefully in gentler conditions (crosses fingers). And hopefully with someone available to assist, fire it off on a hand launch. And then we’ll see.

Oh, and also, there were good parts. Such as: (i) my custom/somewhat idiosyncratic tailwheel approach worked wonderfully—the thing was actually pretty maneuverable on the taxi—at least when I could get it to taxi. And (ii) the wing is certainly tough enough to take the odd turtling right onto its tips, the fuselage suspended upside down above it. As I had a few of those.

So I made a few more modifications to the odd beastie described in the previous post…

Main one: moved the wing back some 25 mm so I could get it to balance without adding weight to the nose (which had been the previous approach).

Also reshaped the bits that hold the wing onto the fuselage, made ‘em a bit rounder. Seemed like the thing to do.

… and the decals are on. Next images, with any luck, will be of the thing flying.

(/Crosses fingers.)

So to the left (click for larger) are buncha shots of a motor glider I’ve been building.

It’s a (somewhat modified*) Dynaflite Butterfly, for the record. Big thing—that’s an eight foot wingspan you’re looking at, in case you’re wondering.

It’s kinda an odd thing, too—designed to gain altitude on that tiny, pretty, efficient little four-stroke engine (an OS Engines FS-30 Surpass—my call—kit calls for a .10 or .20 two stroke, but I figure the four stroke will idle better, which is key with such designs) then glide back down. As I was telling βper in the comments, this peculiar mode of transport has a way of making it an endurance champion: in contrast with more typical R/C stuff, which frequently flies for like 15 minutes at a time, there are reports of these things, with appropriate engine setups, staying aloft for an hour or so—the eventual limiting factor bringing them down is, apparently, sometimes not running out of fuel so much as the receiver battery finally giving out.

The crazy chrome colour thing was my idea—it’s kinda a retro plane, so I got to thinking: let’s go for that silvery early-space age vibe. It worked out nicely, but it did have one complication: taking pictures of something like this in the sun is difficult to do. Had to wear thick, serious, UV-rated boarding shades just to get the shots, on account of the fact there’s almost nowhere to look where the sun isn’t going to come back at you in some direction or other. When I was finished with the shoot, I saw spots for like an hour, I swear.

The plane’s all but done, balanced (tho’ I may move the wing, a bit, to get rid of some of the weight that was necessary for this), its engine run up and tested (and it sounds lovely). Just waiting for some pretty decals. I’ve contracted with a graphic designer who already had a design I rather liked for that purpose to print some up, and these are apparently just now drying; I should have them affixed, shortly. It shall be dubbed ‘The Surfin’ Bird’, in accordance with its mode of flight, and the decals, too, are in this theme.