Saturday, June 30, 2007

Resistance is futile

We have all succumbed to the dark side. Two of the kakis madiened their trex 600 Nitro today. Woot!.

The trex 600 N looks good with its aerodynamic canopy and CF frames feels sturdy enough. Its definitely much lighter. When i lifted it up, the trex600N with full tank feels lighter than my raptor without fuel! The wires can be nicely concealed and the battery tray allows the electronics to be mounted neatly.

There were some minor issues though. The starter coupling lost its grip on the starter shaft a few times, had to really tighten them. The tail pitch slider if pushed all the way to the tail case side can get locked. This happened in one of the machines and the tail went crazy. Luckily the damage was not much. Proper limits must be set on the gyro. The CF align tail blades are quite soft and hollow. It broke easily after clipping the grass lightly.

All in all its a good start. Time to have some oily fun.

Trex 600 Nitro pics
Zimmermann pipe -Superby finishing.
Metal head
CF fins
Metal tail
Torque tube
Setup 2
Rev max fitted nicely in the tray.
Last min checks
Running in engine
Locked tail -> crazy piro
Pilots and soon-to-be pilot.
Baby's raptorCKS' s raptor

Thursday, June 21, 2007

Heli comparison guide - Flight cost per min

There were a lot of new helis released over the past year or so. Especially so in the larger sized heli market segment , with lipos becoming more and more affordable, 30-50 size electric helis are making a storm. This has to be one of the best time to venture into larger helis.

Align first came out with the trex 600, Thunder tiger countered with the E550 and E620 series. Let's not forget the nitro helis although they have been around for quite awhile, they still have their plus points. Raptors having dominated the everyday flyer's market for so long are being given a run for their money by Align's Trex 600 Nitro.

With so many choices and factors to think about, we hobbyist have a hard time deciding which one to invest our hard earn money in.

I did some comparison between the more popular helis in the SG market today and this entry will examine the flight cost of the energy system which has to be one of the more important factors in making the decision as the cost for a year of flight can easily run up to a few hundreds of dollars and even more than the heli itself.

The following are compared : TT50 engine on CP 15% nitro, OS 50 hyper on CP20% , 15cells A123 , 6s 4900mah lipo , 10s 3700mah lipo, 90 size engine on CP30% and trex450SE motor on 3s 2170mah.

Some assumptions i made in the calculations. All prices in SG dollars. As i don't own or have owned all these power system before , some of these figures were estimated using details posted by users from various forums. I have gone through quite a number of threads and came up with the figure which i felt was a good estimate.

6 minutes of flight times for electrics is a rough estimate for mix sports/3D type of flying. Hard core 3D will see the flight time reduce and simple flying around will see longer flight time.

Lipos life time are estimated at 50 cycles per pack. Heli flying demands a lot more from the lipo packs, with amps draw hitting 20, 30C often, so 50 cycles are a good estimate. From past experiences if a pack can last 50 cycles is already considered very good. More often than not, they bloat or lose power/capacity before that.

A123 cells are spec at 1000 cycles . With our kind of use, 200 cycles are achievable as some users wrote in various forums. Some of them are running test right up to 1000 or more cycles and these cells have performed incredibly well. Only problems are getting them cheaply from ebay and the trouble of assembling the packs yourself.

For those using other power systems, the figures can be used to do a rough estimate. E.g. Ep8 or Hurrican 550 using 2packs of 3s packs in series just need to double the figure for that of trex 450 size.

The figures gave a rough estimate of the flight cost per minute of flying. Nitro helis are still fairly cheaper to fly. Coming in close are the A123 cells which combine many benefits of lipos at lower risks and costs. 10 cell dewalt packs are around USD100, add in shipping and other assembly costs, 15cells will cost around SGD300. There are now retailers selling them for USD17 per cell. If this figure was used, flight cost per min will come up to 0.35, still very comparable to nitro.

Using 10s lipos will costs almost 2 times that of 90 size engine on CP30%. It maybe to many people's surprise that cost of flying a electric 450 motor sized heli can be more than a 50 size nitro.

Well this is only one factor in comparing the helis, there are many others like power-to-weight ratio, flying constraints, cost and availability of spares, etc , etc , which i will try explore later on. Make your choices and go for it!

Saturday, June 16, 2007

OEM repairs

After the autorotation crash that day, i went down to mockingbirdrc to get replacements and spares. Their oem raptor parts are cheaper than the original TT ones, some almost half the price. The quality feels similar and there is no difference in flight after the repairs.

For the cracked servo tray, i had used some epoxy to glue the crack and it held up well till today. The whole tray broke off and I lost rudder in flight! Was doing a stall turn when the heli refuse to turn when i give input. Managed to stabilise it while it was still pirouetting slowly, i cut throttle and autorotate to safety. Phew.

At first i thought my gyro was dead, when i went closer, i saw this! Broken servo tray. Another lesson, going to get a replacement later.

Wednesday, June 13, 2007

Extra - GG

Took the extra out for a fly last weekend at BR. While doing a super low harrier, tail touched ground and fuselage broke into two. It was a weak point from a previous crash. Decided not to repair and wrote off the plane. A good plane that served well, the only bad thing was like all filton planes, it was too fragile. Hmm no more powered plane in my hanger olready... GG!

Some new toys seen at BR. Multiplex Profi MC 4000 Tx with extra long n big sticks!

New bizoom. Looks boring to WY. haha
New FlightTech 75amps ESC from KP, comes with a 4amps switching Bec, pretty cool

Monday, June 11, 2007

Safe Flying Please!

Today afternoon, went down to Segar field for some heli practice. When i reached, there was already a group of fliers getting ready for flight. I popped over, said hi and do the necessary frequency checks . Its always more fun flying with more people.

A few electrics and one 60-sized nitro warbird. Hmm i thought to myself, is there enough space for the warbird to takeoff and land. So i asked the owner, who seems like a nice guy. He said no problem, just 10 meters is enough for it to take off. Well ok, i think he is quite experience so should not be a problem.

After a tank on my heli, i landed. Then the 60 size warbird was up next. The pilot that was going to fly the warbird was the owner's friend i think. Fair enough it only took 10meters to take off. But what was scary was the way it was flown. He was flying all over the place! The block of flats on the right was only around 300 meters away and he was flying very close over them.
Oh man, not just that , he was flying in front , behind, overhead, everywhere including over the expressway and also very near to the flats. Kao! Dangerously low at times. Being a warbird, it has to be flown fast and there were a few times he was doing high speed low pass diving at the pit area. Freak, if there was any glitch or mechanical failure that's the end. I m not sure about him, but i still want my life.

Towards the end of the flight, he mistimed a landing and had to pull up very last min else it would have overshot the runway and may land on the jogging track. Crap!

I mean fair enough he maybe a experienced pilot but shitz happens when we least expect it. Some things are just beyond our control. It does not mean that if one is experienced he can forget about safety! There is no compromise!

I wished he could keep in mind the safety considerations when flying. The field is not very big, at most can accommodate a 40-size trainer? Besides there are quite a handful of joggers and people around that area at times.

Our aircrafts have limits that need to be respected and this hobby is much better if we stay safe. Not only do we do this for ourself and our machines but also to keep members and spectators safe so we can all enjoy the hobby. There are not much fields left locally to fly anymore, and knowing people here like to complaint alot, the risk of sites being banned from flying will increase if fliers fly around recklessly. Lets not give others a reason to complaint.

So fly safe please!!!

Friday, June 08, 2007

Autorotation boom strike

Crash report : 3rd Jun Sunday

Was practicing full auto-rotations when i misjudged and it came short. I started the approached high up from the left coming towards me, gave it abit of forward speed, flick the throttle hold and started the descend. It dropped fast but descended too far away as not enough forward speed.

I couldn't tell if the heli was tilting forward or backwards when it was near ground and tried to land. Arg! heli tip over and boom striked! It happened so fast, it wasn't in my mind that i could abort the auto.

Need more practice on the descend and learned my lesson : Keep the heli within view and always be ready to abort if need arises.

Bend boom

Double strike!

The damages : boom, support rod, flybar,blade, tail rod.

The force was great enough to force the blade grips over to the other side and made some scratches on the head.
Found out the rudder servo tray had a hairline crack as well!

Tuesday, June 05, 2007


Completed the canopy paint job after 2 weeks. It was sanding and sanding and more sanding. Each colour was sprayed , sanded, sprayed and sanded again to ensure a smooth surface. After which clear coat was applied and lightly waxed.

The top coat was done.

Bottom sprayed in flouro green.

Some parts of the paint peeled off when masking tape was removed. Had to sand and spray again.

Canopy cover was painted from the inside with some leftover tamiya black acrylic paint. Sand it rough first to give the paint something to bite.

Lustrekote crystal clear was applied to give it a shine and fuel proof the paint. The instructions stated it was fuel proof only up to 15% nitro.

The completed canopy! Avant inspired colours kekeke.

Looking good.

Sunday, June 03, 2007

Maintenance done

I had to replace the rusty crankshaft and bearings in the tt50.

Searched around and went to this bearing shop, Kian Ho Bearings, quite near Rotor hobby along jalan besar to get replacement bearings. The shop lady was friendly, i showed her the rusty bearings, she took some measurements with a vernier caliper and found the bearings i need in no time. Saved 10 bucks on each bearings than if i had bought them at Rotor!

See how shiny a new crankshaft is compared to the rusted one.

The engine was assembled in the reverse way it was taken apart. Run-in a few tanks to get things working smoothly again.

Changed the clunk lines and replace the fuel filter as well.

The exhaust gases discolored the clunk lines! and made them rubbery.

TT's fuel filter, came with a small plastic holder.

Took the opportunity to clean up the heli abit. The brush with long bristle is useful for sweeping away all the sand n dirt. Paper towers and alcohol to wipe clean the heli.