Multi charge leads
I was charging an 800mah 2S battery via the JST connector on my multi-charge lead. After the charge was finished, I went to unplug the battery and dragged it toward me over my bench, when the lipo started fizzing and smoking. I suspect the Tplug that wasn't in use at the time shorted out on a pen clip. The effect is as good as shorting out a Lipo across it's terminals.
The terminals have melted and the lipo has puffed so I've junked the battery. To avoid this in the future, I took an unused T connector and covered the terminals in silicone. When you look at all the leads on the harness, if a short is going to happen, it's going to be on the T connector with those exposed terminals sticking out.
S-l-o-w flying KF delta build – the prop maketh the plane
After the lackluster first few flights I got around to putting a 9047 GWS EP Propeller (228x119mm) and wow what a difference. Same 800maH 2S 7.4V battery and RCTimer1400kV 2204-14 motor mind you but with the larger, more efficient prop I was getting good vertical performance and could slow fly stable enough to do a couple of laps in and out of the soccer goals (obviously no net up at the time 🙂 ).
I've still got a couple of battery and motor combos to try out but for now I think I'll put some paint on it to help identify which way is up and have fun with the current setup.
S-l-o-w flying KF delta build – Maiden Flight
Time to see how this baby goes. I used hot glue all around, control horns, motor mount, bottom skin, step.... and everything has held together well. For the maiden flight I used an RCTimer1400kV 2204-14 motor, an EP 7035 propeller, a 2S 800mAH lipo battery. All up weight was 182 grams / 6.4 ounces. Performance was underwhelming. The first few launches were at full throttle hand launch and floated into the ground. A few more gentle shoves got it up in the air and flying. It wouldn't climb vertically but would gradually gain height after a few laps and gentle turns. Rolls were very fast but I'd lose height quick. Inverted flight required about half down elevator suggesting a CG too far forward. I was worried it was going to be too tail heavy according to the recommended CG and made the effort to move the servos forward. After moving the 2S 800mAH battery a bit further aft I think I found a better balance.
I think I might try a 3S 1000mAh battery and maybe an 8 x 4.8 SF prop. Or maybe build one half the size with the same motor and battery - that should get around ok. Ideally I'd like to comfortably get around on half throttle and have plenty in reserve to recover from tight spots.
I got some footage from the keychain cam and will post that soon.
S-l-o-w flying KF delta build – motor mount II
Some 3mm ply behind the motor, probably overkill and a bit heavy but it's what I had at hand, some hot glue and the engine is on. I had to widen the gap for the prop by about 7mm to fit it all in.
With the motor in place I could get a feel for how it would balance. With an 800mAh 2S lipo all the way up front it was still well tail heavy. Add the ESC and receiver up front and it starts to balance out. The challenge will be to get all that gear up forward as possible without deforming the profile of the wing. As per the examples photos in the rcgroups thread, I was going to but the battery on top with the ESC and RX on the bottom. I was hoping to keep the control rods as short as possible by keeping the servos back near the elevons but due to balance, the may have to go further forward.
On to a question, usually the motor is mounted the other way around (baseplate behind the motor relative to the forward direction of the plane) but on this one it's reversed (a pusher). I'm guessing it's not right to simply reverse the direction of the motor so that it starts pushing. The prop is designed to cut through the air most efficiently with it's leading edge so I guess the right thing to do is flip the prop (keep face of the prop pointing towards the front). Maybe that's the obvious answer? Dunno, never built a pusher before.
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S-l-o-w flying KF delta build – engine mount
Add a layer of thin ply to the upright foam and I have a mount. The motor mounts are 31mm apart and the area is about 40mm x 40mm excluding the tabs. Add a couple of triangle support tabs behind the mount will add support.
In the background you can see the 19mm (0.75") wedge that gives shape the the wing. I'm not sure if this wedge is supposed to be shaped or a straight line from the middle of the wing to the leading edge. So for version one, it's a straight line from 19mm down to 0.
Before I start hot-gluing things together, the motor and servos need to be tacked in place to get the CoG right.
S-l-o-w flying KF delta build
After an hour or so of cutting, the basic form is taking shape. A couple of the photos show how to get a nice clean cut 45°. measure the thickness of the foam (in this case 5mm) back from the leading edge, plus a bit to allow for the height of the metal ruler.
S-l-o-w flying KF delta build
The objective is to build a foamy that I can literally throw in the car without worrying about breaking a prop or rudder, and that can be built from el cheapo materials and spares I have lying around.
For the material I'm using a combination of foam core art board and 3mm depron. I was surprised that I couldn't find something suitable at Bunnings after reading all the rcgroups.com posts from the US about the materials available from the local hardware giant.
Here's step 1. Outline on the 5mm foamcore artboard. This stuff is a layer of foam sandwiched by two layers of cardboard. Looks quite strong and light so it should do the trick.
How to fix the E-Flite Tensor 4D foamy bipe
So I flew the Tensor in a bit of wind, it got a bit far downwind from me and I put it in :(. Broke the fuse clean in half. Such a disappointment after enjoying how well it flies. So how to fix it? Well it's taken me a while but I've discovered the world of the hot glue gun.
I've read about the dangers of hot glue guns melting the foam but also the benefits that if done right, the foam cam slightly melt creating a better bond. So here's the repair job, looks pretty good however its yet to be tested in flight. I expect with most repairs, if its going to break, it'll break somewhere else other than the glue joint. We'll see....
VMAA Trophy 2010
The VMAA trophy was held at the state field, Darraweit Guim outside Wallan. It's a two day event open to all clubs in the VMAA. This video shows a few short clips I grabbed between flying and calling for others. Towards the end of this video is some keychain cam video from my Precedent Fun-Fly. I mounted it with velcro and cable ties, vertically on the rudder and rotated the video in software.
Flying Lawn Mower at Warracknabeal
The annual Warracknabeal vintage machinery easter weekend show is on again and while there's tractors as far as the eye can see, every hour on the hour a high pitched buzz can be heard from over the back of the display grounds. Look up and you might be surprised to see what looks like a Victa lawn mower getting about the sky. The contraption is aptly named the 'Cloud Clipper' and was built by Peter, a member of the Warracknabeal Model Aircraft Club.
By the way, if you are one of those who were thinking that we will be talking about a mower that operates so fast it breaks the sound barrier, then we apologize for the confusion. Go check out BestofMachinery for that, they review only the best makers of lawn mowers which you can get on great discounts - they might just have the thing you are looking for.
Peter says the plans came originally from a magazine out of the US. It's a full foam core wing and he had to build a hotwire foam cutter and learn how to use it just for this plane. It has elevons and no rudder. Peter's advice is to keep the nose up and into the wind on landing otherwise it won't be a pretty return to earth. The foam construction has held up well to a few hard landings and the model looks in great shape. Unfortunately the wind picked up today and the model tipped over on the ground, breaking one of the wheels. I hate damaging a model with a hard landing or an outright crash but wind tipping them on the ground! Don't ya hate it.
