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Posted by dusk | Jun 02, 2009 @ 03:13 AM | 4,198 Views
The third Trex 450 came along when I wanted to try the A123 battery technology. It's a 450SA, aluminium frame with plastic parts. The head had been upgraded to all metal and I added some cheap CF rotor blades. Combined with some inexpensive HC digital servos, it flew quite well.

I left it like this until the first crash. The feathering shaft broke mid flight and ejected the blades. The shaft must have already been cracked from a prior incident with it's previous owner. It sheared 3-4mm from one end. A bit bizarre, but sometimes that's the way things go.

During the rebuild, I slightly bent out the front of the frames to accommodate an upright 3S A123 pack. As described in the various build threads, this layout allowed it to fit comfortably under the canopy and maintained the centre of gravity.

Still following the build thread, I swapped the stock motor for a Scorpion HK2221-6 4400kV . Combined with a 15 tooth pinion and an ESC with a governor, I was hoping that this setup would overcome the voltage sag that A123 batteries experience under load.

Test flights proved successful, with the heli flying very well. Lots of power for my skill level, decent if a bit shorter duration, and no more worries about over-discharging the battery. When the battery ran low, the heli started loosing head speed, but there was lots of time to straighten out and land softly.

I still have some work to do with the governor. In the current setup the governor and gyro don't quite gel and result in a bit of tail wag when hovering. A minor, but niggling irritation, that others usually solve by buying top end ESCs.
Posted by dusk | May 25, 2009 @ 12:29 AM | 4,660 Views
Having had had a rather limited run with the first biplane, I decided that the next one needed to be made out of EPP. To this effect I acquired the eflypower EPP bipe. The intention being that I could practice basic maneuvers and landings and then one day get one of the nice balsa sports/3D planes.

The build was uncomplicated and the plane ended up looking amusingly cartoonish. The kids loved it and immediately insisted that their stuffed toys needed to go for a ride in the plane.

So off to the oval we went. I maidened it without incident. It was a decent, but unexciting. The control surface hinging was rather stiff and the performance suffered, but it did okay as a sports flier. Landings, or rather minor crashes, were achieved without major damage, but the wheel pants got beaten up after a while.

Then it was time for the toys to go up. I do have to say that the look was rather cute.

After a couple rides, the kids wanted me to fly inverted, so that the stuffed toys would fall out and plummet to the ground. Amusingly, the toys refused to co-operate . I ended up doing progressively more violent maneuvers, trying to dislodge the pilot. Finally, a full throttle inverted loop ejected it and it went flying off into the distance to the excited cries of my children.

What distressed me, was that the stuffed pilot was followed closely by the lipo battery. The velcro had let go and I would say that it was in fact the heavy battery that finally shoved the pilot out of the...Continue Reading
Posted by dusk | May 21, 2009 @ 10:04 PM | 5,760 Views
This is my most flown plane. Not because it is the best flyer or the most versatile, but because it is the most robust and always ready to go. The worst crash results in a broken prop and a torn off motor mount. Two cable ties, a new prop and 10 minutes work time and it is back in the air.

A while back I accidentally put it into a full speed 20 meter dive straight down into concrete. The battery ejected and folded up like an accordion. The plane bounced about a meter in the air and came down undamaged.

I read up quite a bit about these planes before building one. Being made from EPP the mini-bee certainly appealed. Especially after my two previous disasters with Depron planes.

I tried to make it even more robust by putting in a 6mm flat CF ribbon spar. It was arched to stiffen the wing and give it some torsional strength. Having read reports about the motor mount tearing the trailing edge in crashes, I reinforced the rear with another short 3mm CF spar.

The original motor mount was designed for a brushed motor, so I modified a GWS motor mount to fit. It was glued to a wide flat surface (a bit of a broken heli rotor blade) to prevent it from rocking and to distribute the motor forces along a wider area. The motor mount was attached to the wing with some cable ties, as per the original design.

The motor is a 1500kv "blue wonder". It works very well with a 7x6 GWS prop. A nice combination of speed and thrust.

After about a year, the mini-bee came in...Continue Reading
Posted by dusk | May 20, 2009 @ 10:51 PM | 4,139 Views
I had been toying with the idea of having a second Trex 450 heli for a while. The concept was that while one heli was being repaired, I could fly the other one. Flying planes was fun, but nothing compared to the adrenaline rush of flying an RC heli. I needed my hit, and I needed it on a regular basis

Then a deal too good to pass up came up on one of the local web sites. A Trex 450XL, HS55 servos, Align 25Amp ESC and 420L motor. An older setup, but cheap and apparently in working order.

After I received it and checked it over, I took it for it's first flight. Compared to my original heli, this one seemed all over the place and had only limited power. Okay to fly, but not what I was used to.

Checking it over again, all seemed in order. It was balanced, almost no vibration and the transmitter settings were correct. So what was the problem?

Another couple days on the bench and still no closer to a solution. Then as I was once again going over the servo travel settings, one of the servos started jittering all by itself. Closer investigation showed that the servo would start to jitter when under load. I hadn't paid close attention to the servos, because I assumed that being made by Hitec, they would be of decent quality. After all, I was flying with cheap Hobby City servos in my other heli and they were fine.

This heli came with a couple spare HS55s, so a quick replacement later, I was back in the air. Much better. But then, over the coming weeks, the other servos...Continue Reading
Posted by dusk | May 19, 2009 @ 06:28 PM | 4,118 Views
After the Nasty, I had a quick go at building a delta wing from depron. A small JSW came together and was ready to fly within a day or so. The kids loved it and named it "R2D2", mostly because of the beeps that came from the ESC at startup.

This being my first flying wing, I didn't realise the importance of a slightly forward CG or that a small wing would actually be harder to fly. With predictable results. At least the kids had fun, as they watched "R2D2" plow into the ground over and over again. There wasn't much left of the JSW after that day.

Soon after, I acquired a second hand Flatout RC Bipe. I always liked the idea of biplanes and after watching my last home made plane get mangled, getting a cheap airframe that was already pre-built appealed to me.

My error was to not do a range check before taking off. I'm not sure if it was a bad receiver or a mismatched Xtal, but as soon as the plane got about 50 meters away, I lost all control and it nose-dived into the ground.

I had never seen a plane crumble like that before. Most of my other planes had survived worse crashes with only minor damage. The JSW was repeatedly plowed into the ground and still managed to almost fly , but for some reason the Flatout biplane cracked, crackled and popped into a thousand pieces.
Posted by dusk | May 18, 2009 @ 07:04 PM | 4,197 Views
To be honest, after a while, the STC became a bit mundane. It was fun to fly, but nothing compared to the adrenaline rush of a heli. Having had so much success with Waterdog's build instructions, I decided to try another one of his creations, the Nasty.

It too came together easily and flying it wasn't that much more difficult. It could do anything my limited skills asked of it and allowed me to gain confidence in flying planes with ailerons.

Over time, it acquired more and more battle scars. Being made from depron, the nose scrunched up on almost every ground hit. The flight characteristics got progressively worse, until it was eventually deemed to not be worth while repairing and it was scrapped.
Posted by dusk | May 03, 2009 @ 08:38 PM | 5,375 Views
While the Trex was in for repairs (which is were it spent a lot of its time initially), I needed something to fly outdoors. I didn't want to commit to anything expensive, because I did not know if I would like flying fixed winged craft.

That was when I came upon Waterdog's plans for the STC. The instructions were clear and included lots of photos, which was ideal for someone like myself.

The project almost stumbled on the first hurdle. I was unable to find any bluecore in Australia. They only had stuff over an inch thick. Depron was available, but expensive.

I was seriously considering buying posterboard and going through the hassle of stripping the paper, when I realised that some art supplies come packaged in large protective depron sheeting. The art supply place was more than willing to sell these at a very reasonable price.

This was about the time when brushless motors were getting cheaper and I managed to get a power system and a receiver from eBay for under $50. With all the materials on hand, it was time to build.

Bending the depron wing turned out to be the hardest bit. The depron sheets I had were only 3mm thick and I had glued two sheets together to make a single 6mm thick surface. When bending, the glue layer would refuse to compress, causing the top depron surface to crack.

When the STC was built, I was eager to try it out. Not realising that one should wait for the right weather conditions before maidening a new plane, I went out to the oval in...Continue Reading
Posted by dusk | May 02, 2009 @ 02:21 AM | 4,221 Views
Once I got the taste of heli flight with the Medevac, I decided to buy something bigger that could fly outside. The Trex 450 seemed the obvious choice. Parts were easily available and reasonably priced and there was a lot of information about it on the Internet.

I got this one second hand. It came with all the bits I needed to get me going and enough spare parts to cover the first couple crashes.

It started off as a 450XL model. It had a plastic frame and a partially metal head and tail. The frame was a constant annoyance. The batteries barely fitted under the canopy and it was always tail heavy, but it was fun and cheap to fix.

I learned to hover and do basic circles with this setup, then I decided to upgrade the frame to something better. The Align frames were too expensive, so I ended up with the STK Superframe. You cannot beat a CNC and G5 frame for under $50. The added benefit is that the servos are perfectly spaced and the frame is open and easy to work on.
Posted by dusk | May 01, 2009 @ 10:42 PM | 4,305 Views
This was my first RC model. Received it as a birthday present from my wife in January 2007. We were camping at the time and since it is an indoor model, I ended up flying it inside the tent. That was also when I broke my first set of rotor blades

It has been modded only a bit since then. The most important change was to add new blade holders. They allow me to use Lama rotors, which are significantly cheaper and easily obtainable from eBay. It also means that the blades fold back in a crash and the whole thing is easier to store. The blade holders were made from broken Medevac blades.

The canopy hasn't been on since the beginning. I took it off to adjust the gain on the gyro and never bothered to put it back again.

The batteries I ended up using are the Hextronik 620mAh 7.4V batteries from Hobby City. They have a lower capacity than the original batteries, but they seem to last just as long. Also, they are lighter, which gives the heli a bit more punch.
Posted by dusk | Nov 15, 2007 @ 09:06 PM | 4,927 Views
Can't have a blog without a quick recap of past events. So here we go!

................

Date... early 80's.... location.... Austria....

Young boy fascinated by neighbour flying RC planes in local park. Watches as the afore mentioned neighbour takes a slightly too long drag on his cigarette, while his plane does a spectacular high speed dive towards the ground. Boy learns some interesting German swear words, as the neighbour throws the cigarette butt to the ground and attempts to perform a spectacular 20G turn (remember, this is from a 10year old's perspective) and juuussssttt manages to pull it out, the plane gently brushing against the grass.

Unfortunately, carbon fibre was not as yet invented.

Wings snap, crowd sighs, pieces of plane all over the field. You get the picture.

................

Fast forward to 2 weeks later.

Neighbour is leaving permanently for overseas. Plane too big to fit in suitcase. Being a nice man, he offers his neighbour's son the now mostly repaired RC aircraft.
Boy looks at aeroplane... and sees what is basically a pile of kindling with oily bits of metal and plastic.
Panic ensures. On the one hand, there is the shiny aircraft flying gloriously through the air; on the other, hours of intense back breaking potentially fruitless labour.
Expectant faces wait for a decision..... but the pressure is too much. The boy declines......

.................

Fast forward to 10 months ago. Boy has grown up. Has responsibilities. A...Continue Reading
Posted by dusk | Nov 13, 2007 @ 08:36 PM | 5,182 Views
It's always good to start somewhere!