Akom's Tech Ruminations

Various tech outbursts - code and solutions to practical problems

Hardware Hacks Toys Not all that is hackable should be...

Posted by Akom • Tuesday, December 2. 2008 • Category: Hardware Hacks, Toys
Last week I hacked up my RC transmitter and added a Dual Rate switch
Dual Rate switch
See here: (How I hacked it up).

I thought I was so cool for adding two wires, one toggle switch and two drops of solder to an RTF transmitter (oh and a nice hole too). Well, everything worked great on the ground, but once I actually flew the plane, not all was well - the control range dropped to about 60 feet!. I didn't connect the dots at first and thought it was a broken antenna wire or something, or a new flying site (coincidence). Nope.

Apparently, adding two thick wires radomly into a complex circuit and placing them along the perimeter of the case can have some unexpected results. I took the wiring and the switch out, and all is well again, control range is longer than sanity permits me to test (plane is a dot in the distant sky, but still seems to be controllable).

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Hardware Hacks Toys Hacking up RTF RC Transmitter with a Dual Rate switch

Posted by Akom • Monday, November 24. 2008 • Category: Hardware Hacks, Toys
I can't say that I have a good reason for doing this, other than the potential for letting inexperienced family members fly my plane, but I thought this should be easy enough to do:
RTF Radio with DR Switch


The RTF transmitter that came with my Pitts S2A has a bunch of dip switches, which are not so quick to flip on the fly - and I've played with friends' real professional transmitters - and they have what seems to be useful toggle switches to control this stuff. So I figured I'm gonna pretend that I'm cool too.

The transmitter turned out to be very neatly designed, and finding the switch and soldering a pair of wires was surprisingly easy. Moreover, the cute silver pads on the top corners of the transmitter are actually silver stickers, covering up pre-drilled holes intended specifically for what I'm putting in there - a toggle switch.

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Toys On Wheels, Thrust Vectors, and Gorilla Glue

Posted by Akom • Tuesday, October 21. 2008 • Category: Toys
New Wheels next to old wheels
I upgraded the wheels on the Pitts plane, and what a difference it makes. I never thought it could land (and sometimes even take-off) on grass! (Well, short grass, anyway). I don't nose in every landing now. Just got those 2.50" Sport wheels from the hobby store. The stock wheels are just way too small. I did need to cut the wheel pants slightly to fit them, but I think it is cute the way they stick out. And as you may have noticed, the Fiji bottlenose got a paint job.

Now about those thrust vectors...

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Toys Pitts S2A third video flight, straight and level

Posted by Akom • Wednesday, October 15. 2008 • Category: Toys
I did it! I flew straight and level. Video is available. Since the side of the fuselage seems to be the best place for the 215g that is the camcorder, I needed 200+ grams on the other side... or less all the way at the tip of the wing? Then it hit me... I have two lipo batteries, about 100g each. And that is how the balanced Fiji Bottlenose was born.
Balanced Payload

In addition to balancing the plane correctly, I finally got to cleaning the camcorder lens, which helped a bit with the sunspots and artifacts. I also covered the microphone with a bit of soft grey packing foam to act as a windsock - and the sound is no longer clipping from the airstream.

The details...

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Toys Pitts S2A second on-board video flight

Posted by Akom • Tuesday, October 14. 2008 • Category: Toys
This morning I thought I'd test my luck a little more, and mount the camcorder (Panasonic SDR-S10 at 220 grams) on the side of the fuselage. Visually, it just seems safer there - in a crash I expect the wings to protect it. On the downside, it unbalances the craft a lot - 635g plane with 220g of now unbalanced payload! But I did it anyway.
Camcorder on the side

See the video...

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Toys Pitts S2A Bottlenose motor mount rebuild

Posted by Akom • Monday, October 13. 2008 • Category: Toys
I didn't see this coming - hesitated in my landing approach, caught a gust of wind, clipped a cute little pine tree - and dove straight down 15 feet, carefully missing the soft lawn and hitting the packed dirt road. Front end demolished - engine cowl and engine mount are in pieces, fuselage cracked. The prop saver may have helped the motor survive this adventure.
New Engine Mount (mount cross is inside bottle)

I tried to find suppliers for these parts (again), but nothing turned up. Other than buying a whole new plane, I don't see a way of getting a new motor mount (that seems a little silly, no?). The fuselage is easy, Gorilla glue got that back together in an hour or two. (In fact, I've already glued the fuse with it once, and that weld did not break).

But the mount?

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Toys First Video Flight!

Posted by Akom • Sunday, October 12. 2008 • Category: Toys
I've been thinking about aerial photography for some time, and I've worked out exactly what equipment I'd get too, but for now I'm not allowing any funds for this expenditure. I figured that AP is way in my future, but this morning I just decided - what the heck. FPV (First Person Video) may not happen right now, but at least I can record the flight and watch it later. So I went and weighed my SD camcorder... Panasonic SDR-S10. 220g or so - not too bad (My ultra-compact Optio S550 is 270g, and that's only a still camera!!!). The plane is 635g with battery. Hmmm...

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Toys Sapac Pitts S2A electricals and motor replacement

Posted by Akom • Monday, October 6. 2008 • Category: Toys
I killed the motor. Apparently ramming into pavement at full throttle (don't ask. From now on, when something goes wrong on takeoff, I abort) is not such a good thing for a long thin shaft and a firmly bolted prop. A few flights later, the motor died and started singing instead of spinning. One of the windings seemed to be busted (based on measuring voltage with a drill).
Measuring Current

Anyhow, I did some measurements when it was all good, and here are some specs: With the stock Sapac 2830 motor and the 3-blade 9x8 prop, the battery put out as much as 12.5A at full load (my measurement, massive analog meter). The battery is 10C, 1200mAh, meaning that 12.5A is about as much as you could ever expect it to put out, in other words - running dangerously high. I also got a 10C 1800mAh battery and the plane had noticeably better thrust (haven't measured the current), so it actually did want more than 12A!

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Toys Exceed Pitts S2A third flight (wind and broken rudder)

Posted by Akom • Tuesday, September 9. 2008 • Category: Toys
I finally have a fully charged battery so I'm off to have a nice long flight. Or so I thought.

So there was some wind this morning - not too much, I figured - I can handle this, I've flown with wind in the simulator. Went out to a different field today - more open, less wind cover. Took off from a sandy path, plane rolled easily and I pointed it into the wind for takeoff. It took off before I even asked it to, and the fun began

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Toys Exceed Pitts S2A second flight

Posted by Akom • Sunday, September 7. 2008 • Category: Toys
The broken wing was dry this morning (see previous post) and the wind was almost nonexistent, despite the hurricane that went through overnight.

I'm off to fly! This time around I moved the servo pulls to the second hole, making the controls slightly more sensitive (I have been getting better with the simulator, and the last flight it felt a little unresponsive). I also set the elevator to fully horizontal position - I had it pointed down slightly last time, also out of caution, but this morning it didn't even want to take off this way.

It flies!

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Toys Exceed Pitts S2A first flight (and crash)

Posted by Akom • Saturday, September 6. 2008 • Category: Toys
First flight! Yay! I guess I consider myself good enough after playing with the simulator for a while.

After a little trimming (adjusting the servo pulls with the tiny allen wrench they supply) I got on my runway (a paved road on a park slope) and (with some trepidation) pushed the throttle forward. It took off, with some effort, and flew!

I think it flew with what others have described as a tail-heavy tendency - it seemed like I was always pulling too hard on the elevator - or maybe I was, in the turns, I'm not sure. In any case, all I had to do was push the nose down every so often and it would avoid stalls... which it survived just fine anyway, just taking a small dive and recovering. I circled the area for about 2 minutes, and then just as the plane was getting away from me to the point of "a bit too far", it suddenly disobeyed...

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Toys Assembling the Sapac Exceed Pitts S2A 4ch R/C plane (and some improvements)

Posted by Akom • Friday, September 5. 2008 • Category: Toys
I have to admit, I've never owned a real R/C plane before, so the following may be painfully obvious to someone who has. When I say real I mean hobby grade. OK I admit it, I had a Hirobo Shuttle nitro heli for a while, but I crashed that so many times that I'd rather not go there. What I learned in the process though is - simulator software is not optional. So this time around I borrowed a friends' copy of Realflight G4 with the controller. I am steadily getting better.

Anyway, so I bought the RTF version, which, I have to keep reminding myself, stands for Ready-To-Fly. Raidentech.com is one of the few places that sold it at the time and I found a free shipping code (CJFREESHIPPING) on somone else's blog. It eventually arrived, in a very large box (OK so I should have expected that, the plane has a 3 foot wingspan). On to assembly...

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