Okay, yesterday I admitted that I could not do math. According to Sean Foster’s hints on trainer design, the horizontal stabilizer should have had an area of between 20 and 30 percent of the area of the main wing. My main wing is 30 inches with a six inch chord, so it has an area of 180 square inches. For some reason, I did the math wrong, and yesterday’s tail had an area of only about 27 square inches. Today, while watching Pablo Sandoval lead the Giants to a 1-0 lead over Detroit in the World Series (three home runs in his first three at bats? I love this game!) I decided to make a new tail with just about double the total area. I was out of white Dollar Tree foamboard, but I did have some black lying around, so I decided to give that a go. I started by cutting a 5×15 inch rectangle, and then tapering each side to 2.5″. That ends up with 56.25 square inches, which seemed pretty good. I made the vertical stabilizer out of a 5×5 inch square, which I then tapered to just 2.5″ at the top. I didn’t bother cutting in the rudder and elevator, because this was really just a model (which I might use as a glider test platform later, but not as an RC model).
The black foamboard doesn’t photograph well, but here’s the tail installed.
New tail on the prototype…
I think the proportions are more pleasing. In the real RC model, I’m thinking I’ll need to stiffen the main body, either by embedding struts, or doubling (or tripling) the body thickness. The balance of the glider is almost dead center now, well behind the wing, so it won’t fly as is. But I think it will probably fly pretty well once I get some more weight in the nose (in the RC version, it seems likely the motor, receiver, servos and batteries can compensate).
With some luck, I’ll get to a flight test this weekend.
Addendum: I tried to balance the plane by taping some weights to the nose and giving it a few practice tosses. Sean’s page suggested that the CG would be about 25-30% back from the leading edge of the wing, but when I adjusted the weight to balance, the plane was clearly nose heavy, and accelerated into a dive. Just before bed I plugged the numbers into a CG calculator, which suggested that with the spacing I chose, the CG should be better placed about 3.5″ from the leading edge (or about 60% of the way back). I’ll have to give that a try soon. But it’s time for bed.
I haven’t done much flying this week, in part because we’ve begun to get some rain here in the SF Bay Area, but also because I have just been having difficulty controlling the Nutball. I began to think that what I needed was a proper trainer airplane. A couple of weeks ago, I read this interesting post by seanfoster on the flitetest website, detailing some basic design dimensions that you could use to generate a docile trainer. I decided to try to use this proportions and mate them to the KFm-2 wing that I made a couple of days ago, to see what the overall proportions would look like. I decided to use some of my pink 1/2″ foam for the body, and made a tail out of Dollar Tree foam board. The idea here was not to generate a flying model, but really just to put together the pieces in the proper proportion to see what it looked like, and judge the overall balance and sturdiness of the construction, and just whether I liked the overall size and shape.
Here’s a couple of pictures of the resulting airplane, just hot glued together and photographed in my living room.
The overall body length is 30″, which is five times the six inch chord of the wing, which has a 30″ wingspan. The body has a maximum height of 3″ (10% of the it’s length) and the nose section tapers down to 2″ symmetrically, while the back section starts tapering back to just 1.5″, starting at 12″ from the front of the nose. The tail is 9″x3″, with a 3″x3″ vertical stabilizer, and 1″ elevators and rudder sections. The resulting aircraft is quite tail heavy, but of course lacks the motor that a real RC airplane would have. I don’t have any spars in place, so the body itself was pretty floppy. I’m not displeased with the overall shape, although I wonder about the tail: it seems a bit small to me. I also did not give much thought to the ailerons or elevators. I was thinking of having just elevator/rudder control, and wonder if their relatively small control surfaces would make the plane difficult to control. The guidelines provided are for four-channel control, I was wondering if a three channel rudder/elevator would be easier to do, and would therefore also require additional tail changes. I’m trying to come up with something docile and easy to fly, rather than acrobatic, so perhaps less is more.
I might try weighting the nose of this prototype a bit to get it to balance, and then see if it works in a glide test. If I do, I’ll be sure to shoot some video and let you know how it works out. Stay tuned.
Addendum: Sigh. Apparently, I can’t do math. The recommendation is that the tail have between 20 and 30 percent of the area of the main wing. My wing has an area of 180 square inches, whereas my tail has an area of just 27 square inches (about 15%). A better tail would be 12″ by 4″, with a 4″x4″ vertical tail, which would have an area of about 48″, which would be about 27% of the main wing area. Luckily, a little isopropyl alcohol on the tail section will dissolve the hot glue, and I can try replacing it. I should have double checked my math before starting.
As I was watching Vogelsong pitch a gem against the Cardinals, I thought it might be cool to try some additional experiments with paper/foamcraft and try to create a simple (even trivial) wing from some Dollar Tree foamboard.
I had previously experimented with building an Armin wing as described by Ed at Experimental Airlines. It generates a nifty wing, with a true airfoil shape. But it’s kind of complicated, and I wanted to see how simple I could make a wing using Dollar Tree foamboard. I had very modest goals: just something that might provide a little better lift than a flate plate. I decided to try fabricating a 30″ wing with a 6″ chord, in the style of a Kline-Fogelman airfoil, in particular the KFm-2 design, which has a step at 50%.
Fabrication couldn’t be simpler: I just cut two pieces from foamboard, one 6″x30″, another just 3″x30″. I could have just hot glued them together, but I decided to be a bit more refined. I stripped the paper off one side of the 3″x30″ piece, and scored and stripped a section the same size off the 6″ piece, so that I would be gluing foam to foam. I then spread a fairly reasonable amount of Gorilla glue to one side, and wiped the other with a dampened paper towel (the water is supposed to enhance foaming, making the glue spread out). I then placed them together, and put my 2″ wide steel ruler over it, and clamped it down to my workspace to set. The hardest thing is waiting for glue to dry, but after an hour, I could see that the foaming had caused a tiny amount of the glue to eek out of the side. I unclamped it briefly to check it out: it seemed very much stiffer than the single layer, and might not even need additional stiffening to use it in a small, lightweight trainer. When it’s completely set, I’ll cut a bevel onto the front, which should give it a tiny bit of aerodynamic efficiency and then cover the leading edge with some packing tape.
The specifications on the Wiki page say that a KFm-2 wing should have a thickness which is 7%-9% of the wing chord, which means a thickness of about .4″ to .54, this wing turns out to have a thickness of about 3/8 of an inch, which is a tiny bit thin, but I’m going with it anyway. For a novice trainer, some dihedral angle would be useful as well, so I think I’ll score the middle and fill it with hot glue. I could add some ailerons, but I think maybe just elevator and rudder controls would make sense, so that would probably be it for the wing.
Not sure what I’ll do for the body yet. But my goal is simple, simple, cheap and simple.
Pictures later.
Addendum: Okay, here are some pictures.
The full wing…
The bevelled leading edge…
I didn’t do an amazing job: it’s just an experiment after all. I cut a rough 45 degree angle through the top layer of the wing, and then beveled it with a dry wall sanding block. The results are pretty reasonable. I scored through the bottom of the wing, and cracked it, filled it with glue, and held it in place at the dihedral angle (just the height of a book I had on hand) until it set, and I then covered the joint with packing tape. Overall, I’m pretty happy with the result of the experiment. I think it’s usable.
Carmen suggested that we try to go out and fly my Nutball, since she hadn’t seen it in the air before. Our local park seemed too small, and Cesar Chavez turned out to be windy, so we did a quick websearch and discovered that the Lime Ridge open area in Concord was popular with fliers, especially on Sunday. So, we headed over there and gave it a whirl. It is indeed a pretty nice area, and there were a couple of other fliers giving it a try (and doing a much better job of it). My own attempt at taking the Nutball up resulted in a couple more snapped props. Sigh. But I did have my little camera in the back, and Carmen shot some video of my launch, so at least you all can laugh at it. Here it goes:
Okay, my last blog mentioned the over-pressure situation aboard the SpaceX Falcon 9 launch. Today, I experienced my own launch failure: flying my homebrew Nutball RC plane. This was my “new, improved” version, with a swappable fuselage, and 5 degrees of down angle on the motor. Mark Harrison and I decided to get out and give it a try this morning around 8:00AM, before the wind picked up. Sadly, traffic was miserable, and I didn’t make it to the Berkeley Marina until almost 8:30 (averaging a whopping six miles an hour, sometimes I hate the Bay Area).
Once I arrived, we did a quick check, and launched. I should have notice two things: the new Nutball is significantly more tail heavy, and we needed to trim the elevon position down. The net result is that the plane did a quick loop, traveling a distance of about twelve feet, and mashed right back into me, hitting my hand fairly hard. Ouch. Just banged it up, and put a couple of scrapes. It’s then that I learned that real RC enthusiasts keep bandaids in their fly kit. I’ll be getting some for mine soon. Luckily, Mark had some.
But now that my plane had tasted human blood, I felt we couldn’t let that be. We adjusted the balance by taping an additional battery to the front, and had a couple of relatively unstable flights. I augured in pretty hard once, snapping another prop, but the plane held up pretty well. We decided we needed more weight up front, so I put a larger battery as a counterweight, and sent it up for what would be the best flight of the day. With additional weight up front, it flew pretty stably. Even with the exponential programmed into the transmitter, only very small corrections were needed to direct the flight, and it flew well with about 1/3 throttle. I flew it around for a minute or two… when it suddenly did a fast pitch down into a dive. I managed to cut the throttle, and pulled back on the elevators to bring the nose up. Unlike all my other previous attempts at recovering, this worked out rather well: the nose came up, the plane leveled out about 12 feet from the ground, and I set it down softly on its belly. Unlike all previous landings, I didn’t even knock the taped-down counterweight off. I considered another flight, but decided that it would be tempting fate. We’ll try again next week.
At lunch, I had another RC related bit of fun: Mark had bumped into Hao Chen during a previous outing to the Berkeley Marina, and had discovered that Hao had begun working with the Monterey Bay Aquarium Research Institute. The idea was that he would launch a flying wing equipped with a first-person video setup from a research boat, and fly it around looking for significant oceanic phenomena. At the time Mark met him, he was practicing flying his large flying-wing drone into a capture net as practice before taking it out onto the boat.
It’s very cool!
Here are a couple of his YouTube videos:
Here’s video of the launching operation. It’s also video of what tossing a plane into the water looks like. For some reason, it makes me feel better about my attempts at flying…
I’m waiting for new props and the like to arrive for more RC fun, but in the mean time I tried to satisfy some curiousity that I had regarding the “trainer” mode that my Turnigy 9X transmitter has. The idea is that if you have a master flyer (like my friend Mark) and a complete spaz (like yours truly) you can chain two transmitters together with an ordinary 3.5mm stereo cable, and have a sort of “student driver” situation, where the master can transfer control to the novice, but take it back if the situation goes bad.
I wondered what the signal that was being sent back and forth between the radio looks like. Mark had a little pocket digital oscilloscope that he was using to look at it, but because the “trigger” options on the scope were fairly limited, it was hard to see what was going on very clearly. So today at lunch I hauled out my Rigol and decided to have a peek.
The Rigol is a great, capable scope for the $400 new that it costs. What saved us here was that we had a number of trigger options that were not available on Mark’s scope. A brief glance at the scope made me think that the 9 channel transmitter was sending a logic level signal with pulse position modulation. I hypothesized that there had to be a pulse (positive going, by the looks of it) which was long to set synchronization, followed by nine pulses with varying times at 5v, and a low time which appeared to be pretty constant. A bit of tweaking with the triggering showed that the sync pulse was about 6.5ms long. The positive pulses ranged from somewhere around 0.65ms to 1.52 ms, and the low durations where a pretty constant .4ms. Each of the nine channels seemed to be matched out in order.
It would be very simple to hook up an Arduino, Atmel, Propeller, what have you to read these pulses and map them to control inputs. I was thinking that making a small board to read them, and then implement a USB HID device to send them a computer might be a fun thing to do. If your cpu uses a 3.3v level, you might want to use a BJT to invert the signal, and then compensate for the flip in software.
I’ll try to get some screen grabs of the control signal soon, and post them here.
I apologize for not updating my blog recently, but sometimes life intervenes, and it seems like you just aren’t doing too much that would be of interest. A combination of a home burglary, increased load at work, and perhaps just a touch of malaise brought on by the political season has meant that come evening, I haven’t felt much like writing.
But I have been working on RC airplanes. I’ve been trying to record video, and some of that has been going onto my YouTube channel. In case you aren’t a subscriber over there, here’s the result of about a month’s worth of experimentation.
First of all, I must thank Mark Harrison of the Eastbay RC blog. He has been serving as a mentor to me, and has been patiently guiding me toward… well… if not competence then at least experience in RC construction and flying. His F22 inspired me to build one of my own, which he flew during this maiden voyage:
But this plane lacks dihedral and lift, so it’s a bit hard for a complete newbie like myself to fly. To get me some stick time, Mark let me fly (and crash) a series of his own planes, such as his Easy Star:
I decided that if I continued to crash his planes, it might eventually put a strain on our relationship, so I decided to construct a Nutball of my own. I recently took it out, and shot this video with my iPhone. It also shows some of Mark H.’s creations (apologies for the low audio, recording with the iPhone seems impossible for me without covering the mic input):
Here’s some nauseating video filmed looking to the rear from those early Nutball flights:
Since then, I’ve had a few more interesting Nutball flights. Last Wednesday, Mark and I met early in the morning and sent it up. I programmed my Turnigy 9X transmitter with a bit of “exponential control” to help soften the controls, and that seemed to help. I put it tup four times, and only the last one seemed fatal. I did suffer a number of hard nose-first landings, the first of which pushed the axel of the motor back against the firewall, but I simply undid/redid the set screws holding it in place, and we were ready to go again. The next two flights, I managed to get the plane flying for longer and further than I could throw it, but I noted (despite the Nutball’s rather ‘easy to fly’ reputation) that mine seemed to have a proclivity for flipping nose up onto its back. The last flight was going well, right up until the point that an unforseen mechanical failure occurred: the glue joint that held the dihedral angle on the right wing simply gave away, and the wing folded up. Net result was about a 100 foot nosedive, snapping another prop and springing my servo control arms.
Sadly, while I did have the Turnigy camera Velcroed to the wing deck, there seemed to be an electronic issue with the camera: while audio was recorded for the entire flight, when the engine first spun up for launch, the video glitched and was not recorded for these dramatic events. Rats.
I could actually repair the plane fairly simply, but I realized that my Nutball lacked a feature that most instructions inform you to do: angle the motor down by about five degrees. Mine was always parallel to the wing deck. So, rather than fix the old one, I’ll be scavenging it’s internal organs and installing them in a new and improved wing deck. To guard against the glue failure I had last time, I’ll also run a strip of tape along the glue joint to guard against vibrations which expand the joint.
Perhaps by next week, I’ll be back in the air again. Stay tuned.
Oh, one last video: Mark H. brought his tiny quadcopter out to play, which he demoed with a short flight. We put the little keychain camera aboard and recorded this flight. It was very stable and smooth in the air.
But I figured you guys might like some additional details. As I mentioned before, I decided to build a clone of the Axon, a nice light FPV platform designed by Ed of Experimental Airlines. It’s a neat little plane, and is in many respects very similar to the Easy Star. It has a pusher prop mounted near the middle, a 55″ wingspan, and is about 42″ long. It’s constructed out of foam board tubes for the body, bonded together with mounting tape and a little Duct Tape. The wing’s are a pair of Armin wings (see Ed’s videos for instructions on how to make them) and have a 5″ chord with 1.5″ elevators. I have ordered the motor, ESC, and batteries needed to get it into the air, as well as a 5.8ghz video link setup and camera. Most of those items are back ordered, so it might be a while before this thing gets into the air, but I think it looks good so far. You could probably build one in a single weekend without any sweat.
Early on Sunday I was out at Home Depot and acquired some additional raw materials for my RC plane construction projects. I got a 4×8 foot sheet of 0.5″ pink foam, a 36″ chunk of 2″ angle iron, and a new 4 foot steel ruler (I know I had one somewhere, but darned if I could find it.) Anyway, after my experiment with making a square box fuselage, I thought I would try making a wing with an “Armin” wing, as shown in the YouTube videos of Experimental Airlines.
It took me about 10 minutes to put together this 30″ wing, with a 6″ chord.
This is the simplified version of the wing, which has a trailing edge which is two thickness of foam board, and does not include an integrated elevator. The construction followed these directions almost entirely:
I didn’t get the tape down as smoothly as might have been hoped, but it still looks pretty good. I’ll next try the improved version with the tapered trailing edge, and maybe a carbon arrowshaft stiffener (although this wing seems plenty strong.)
I was feeling pretty lazy today, but I still wanted to do something working toward an eventual new scratchbuilt RC plane project. I’ve been watching a lot of stuff on YouTube, most notably the videos by the Joshes at flitetest and the great YouTube channel of Experimental Airlines. Experimental Airlines seems especially great: he makes some very interesting planes using a variety of neat techniques, made mostly from Dollar Tree foamboard and clear packing tape.
So, I decided to try to make a section of this fuselage, just as a test. I had some clear packing tape lying around, so I layed down about a foot of it on one side, not nearly as carefully as he does, but I was doing this in my living room while watching TV, and the light wasn’t really as good as it should be. I then followed his directions, although again with perhaps a bit more haste than I should have. I had some difficulty getting the final glue joint to really lay down flat, I think if I had some angle iron and some clamps, it would have helped. Still, another layer of packing tape laid along the bottom made an entirely serviceable, sturdy tube.
A finished twenty inch section of tubing.
The end view, with the reinforcing inner gusset.
I have a piece of iron angle iron which would have worked nice as an interior clamp, but it was dirty and rather oily, so until I can clean it and wipe it down, this will have to do. I doubt I’ll use this directly in a plane, but it was good practice (and cheap, since Dollar Tree foam costs a dollar). I suspect next time I’ll get the final joint better. He also has another method, which uses Gorilla Glue, which for this application might be easier to manage. I might try that out soon.
Stay tuned for an actual airplane construction project.
Mark H. over at Eastbay RC and I finally got together to test out my first attempt at scratch building a radio controlled aircraft: an F-22 inspired “foamie”, which an aircraft constructed entirely from EPP foam, hot glue, a couple of short carbon fiber rods to stiffen, and hot glue. Did I mention the hot glue?
Last Friday, we tried to get out to Cesar Chavez park near the Berkeley Marina and fly, but unlike the great weather early in the week, Friday had strong winds and a bit of rain. Mark got his F-22 up in the air for a couple of flights, but mine suffered a glue failure on one of the control horns, and it did not make it into the sky.
But this Wednesday, we did manage to get some better weather. While overcast, it was nice and still. It should be said at this point that I’ve never flown an RC aircraft before, and for my first construction project, I could have chosen a better plane (although I think it looks cool, and that’s what counts!). Thus, I let Mark and his experience man the controls, hoping that even if the plane was poorly balanced or constructed, he’d be able to get a couple of flights from it before it fell apart and its organs harvested for a future aircraft. I was thus mostly a spectator, and shot some video with my iPhone. Due to poor planning, I didn’t have a lot of space left on the iPhone, so I only got the first part of its maiden flight. We actually sent it up several times, and included a couple of flights where we taped my $8 keychain video camera to the nose. I stitched this video together from both the iPhone footage, as well as the nose cam footage. Not too bad for my very first foray into RC construction.
Mark wasn’t about to let me get away without at least giving a try at flying. He felt (and I agreed) that perhaps my airplane wouldn’t be the best plane to start with. In a fit of generosity, he let me take the controls of his own EzFly, a much more forgiving slow trainer type aircraft. It’s a great little plane, which has a KFM style wing, some dihedral to keep it level, and a nose consisting of three layers of foam for maximum energy absorbing capability. My first flight was good evidence that perhaps this trainer was a good idea. After a relatively smooth takeoff, I cartwheeled it into the ground, causing it some injury. But with some quick repairs (blue masking tape) it was ready to fly again. I did a few more flights, and quickly improved. For my last flight, we taped on the nose camera again, and I sent it into a high soaring flight.
Sadly, the video during the ascent when the motor was under full power exhibited an odd distortion caused by the vibration beating against the rolling shutter of the cheap camera. But when I cut the motor and started coasting down, the video was pretty cool. I have a rough unedited version below, sorry for the 40 seconds of mark setting up his iPhone to record me flying. (Warning: there is audio on this one, be prepared for motor whining!)
Not bad for a first outing. I think that the F-22 will remain until I get a little more experience in flying. Mark’s EzFly impressed me so much, I think I’ll have to construct one of my own (Mark has already muttered about splitting an order of some more sheet foam, I’m in!). We might try to figure out why the vibration on the EzFly seemed so much stronger than the vibration on the F-22. The high soaring flight of the EzFly was really nice, and once I got the hang of being gentle on the rudder and ignoring the elevators entirely (use throttle to go up and down) it was almost relaxing to fly.
If you’ve ever wanted to get into RC, it seems like this kind of construction and all the great online resources have never made it easier (and it doesn’t hurt to have a patient and more experienced friend to help you.) I’m hooked. Expect some future planes and flights (perhaps better documented than this build).
Addendum: While investigating the vibration issue, I found a number of other vids which demonstrate the effect, although none perhaps as severe as the one I saw. Someone suggested that we might have been running with an unbalanced prop: given that I had mashed this thing into the ground, it’s entirely possible that I bent it up. But during my investigation, I found this extremely nice video of a wing mounted camera on a gorgeous looking P-51. For your viewing pleasure:
I received my second email inquiry yesterday (yes, two whole emails) asking me why I hadn’t been posting to brainwagon lately. It’s gratifying that both of my readers would each send me a note asking if things were all right, so I thought rather than addressing you each separately, I could double my efficiency by creating a post.
There are many reasons for my apparent slowdown in posting. My new project at work is taking up more time. I haven’t done much amateur radio lately, mostly because I need to rework my antennas (I want a more permanent way to route coax inside, rather than just “opening a window”), and the programming muse has seemingly left me: I can’t seem to muster a lot of enthusiasm for it at the moment.
These would by themselves normally be enough to slow me down, and perhaps bring a temporary halt to blog posts. But there is another reason: the unavoidable drone of the election season.
You see, I’m a person of fairly strong political convictions, and the election season always presents enough fodder that daily I find myself yelling at the television. My temptation in moments of weakess is to turn these diatribes (well founded as I believe them to be) into blog posts, but I don’t think that my readers (both of you) come to brainwagon to read my political positions. If I invited you to my house for a barbecue, I’d be a terrible host if I simultaneously subjected you to rants on the subject of politics or religion. I view brainwagon as a place where I can talk about interesting things of little consequence. I’m going to try to keep it that way.
On the brighter side: some cool projects are underway. The F-22 RC airplane I began several weeks ago is mostly completed. With the help of Mark Harrison of Eastbay RC, I had the thing entirely assembled, and we were set for a trial flight on Friday, but sadly after a week of beautiful weather, Friday dawned cold, with a light drizzle and strong gusty winds. We might have braved it, but I noticed at the last minute an issue with a loose control horn on the elevon, and it would not have been controllable. It needed a return to the workbench for a fix.
When I got back home, I pondered another problem that I had with my assembly, if you check out the following video, note the placement of the servos:
Did you see the issue? the servos are mounted very near the slot where the propeller will be mounted. In fact, when the elevons are in the down position, the little control arm for the servo comes uncomfortably close to the propeller. I decided that while I was fixing one of the control horns, it would be good if I unglued the servos and mounted them further back.
And here’s where having a great mentor like Mark really helps: he informed me that isopropyl alcohol applied to the glue joint would wick in, and I’d be able to peel the glue off. A trip to Walgreens and $2 got me a nice bottle of 91%, which I applied with a cotton swab. A few minutes of waiting, a little wiggle, and the servos popped right off. A little more alcohol applied, and I was able to peel the remnants off the foam and the servo. Very cute.
Today, I hope to get the new, shorter control arms in place, with better control rods in place, with hopefully less flexure. Then, the question will be: dare I try it out? I actually have no experience at all with RC planes: I was going to rely on Mark to help me get it off the ground and maybe avoid a crash by using “trainer mode” on my transmitter (enabling him to take over and fly). I probably shouldn’t have begun with the F-22. Something with some dihedral and maybe even a real airfoil so it can glide in without power would be better for a beginner, but it looks really cool. 🙂 I expect that after two or three flights, it will be in such bad shape I’ll have to harvest its organs for use in another plane. But I will have learned alot.
I’ve already begun to plan a second plane, and to acquire the parts for it (whatever it turns out to be). Ultimately, I’d like to get to the whole FPV (first person video) setup, and be able to fly with cameras aboard, but I think until I gain some experience, it would be pointless (or even counterproductive) to spend lots of money on equipment. After all, you have to walk before you can run.
But I did find an interesting gadget that’s a baby step in that direction: an $8 Turnigy keychain video camera. It records MP4 video at 640×480 resolution onto a microSD card (not provided). I had a 4GB class 4 card, which worked okay for early testing, but it seemed like it had a problem maintaining full frame rate with that, so I ordered a couple of nice little Class 10 cards from Amazon, and they seemed to work out very well. Since my plane isn’t ready for flight testing, I decided to test the camera by velcroing it to the license plate holder on my car, and taking it for a short 15 minute drive. I then took the video and post processed it with ffmpeg to turn it into a time lapse video (25x faster) and got this result:
The overall clarity is not bad: the automatic exposures can sometimes lower contrast and wash out the image, but perhaps less than I might have expected. The biggest problem I suspect I’ll have is that the field of view is quite narrow, and thus when mounted on the airplane, may jerk around a lot. But for a total investment of around $17, it’s perhaps better than I might expect.
Stay tuned for more, and thanks for your patience!
Okay, I haven’t made a lot of headway, but I did at least print out the pattern for my F-22 and cut the pieces for it. It’s literally the very first time I’ve done this, so the pieces aren’t perfect, but they aren’t bad. Witness:
The foam pieces for my F-22, with the radio transmitter to give some sense of scale.
I basically made the patterns by printing out the pieces, taping them together and then cutting out each individual piece. I then held them down and traced each piece with a wide point sharpy onto the foam, and then cut them pretty much freehand with an exacto knife, trying to cut pretty much all of the black off. It mostly worked okay, but the cellular nature of the foam made for some slight rough divets, and I found the first knife I used was actually a bit dull, which is a no-no. Switching it to a new blade helped, and the main body deck (which I cut last) was pretty good.
It’s some progress. I’ll think about it a bit more, and then figure out what else I need to do. I know I need to put in some carbon fiber rods across the body to stiffen it. I’ll have to review some of the online help to figure out what the best order to do things is. It also appears that Mark’s version has some kind of internal stiffening between the two identical body parts, not sure though, I’ll have to check it out.
Do I really need another hobby? Sigh. Oh well, it appears that whether I need one or not, I’ve taken my first tentative steps into the world of radio controlled airplanes, and I have Mark H. of the Eastbay RC blog to blame. Mark is a fellow Pixarian, and has lately been sucked into the world of model aircraft, building both autonomous UAVs as well as more conventional aircraft. I first started talking to him about this stuff through our interest in the Arduino, but he’s got me interested in scratch building my first RC aircraft.
To entice me (and to serve as a model for copying) Mark left his version of the F-22 Raptor in my care:
Mark’s scratchbuilt F-22 Raptor, in EPP Foam
The design comes from this posting on rcgroups.com, and seems pretty straightforward. But I’m so inexperienced with this stuff, I was a little bit intimidated, so I spent most of the weekend staring at the plans, and digging up further resources. The page above listed this nice vimeo video:
which is also available in four parts on YouTube (glad to find, so I could watch it on my Apple TV on the big screen TV):
When I start working on mine, I’ll post more pictures and information. I did stop by Harbor Freight and picked up some X-acto knives and one of the Dremel-tool-knockoffs, and I picked up a Turnigy 9X transmitter-receiver pair. Stay tuned for more soon!
