Saturday, March 31, 2007

Heads up

Next up was the main rotor assembly. Slowly worked from the swash up. The kamasa head assembles much as the stock one accept for the metal blade grips. The metal blade grip had to be heated in the oven to install the radial bearings for a tight fit.

The washout arms and the bell-hiller mixing levers have 2 holes on each side of the pivot point. They can be adjusted to give different pitch range to suit different flying style.
Red dampeners and green ultra light paddles used instead of stock ones.
Kasama tail feels solid and no slop.Hands were starting to ache after all that screwing. lol. The mechanics part is done. Up next will be the electronics setup...

Sunday, March 25, 2007

Main frame assembly

Build started! It was fairly straight forward and manual has large clear pictures to follow. The assembly guide from is also very useful. There are quite alot of resources out there so i will just add some of the useful tips i found.

Edited : Found another good titan review at rcuniverse here.

Kit is build stock with a few upgrades, swapped out the plastic white frame spacers for Aluminum ones (PV0104) for reinforcement, changed to the new 8.73 ratio main gear (11Tpinion , 96T main) , replaced stock clunk tubing which are known to fail after few flights with thicker ones.
A good set of tools will make the assembly easier. Some of the tools used. The denatured alcohol is used to remove any grease n oil from the screws before applying loctite.The fuel tank nipple is quite tight and hard to remove just by pulling. One easy way to remove it is to use a small screw driver and slide it under the notch and slowly lift it out. Less risk of breaking.One of the harder steps was putting the snap ring onto the one way clutch shaft. A snap ring plier would make this easier but i didnt have any around. Looked around and found the ball link plier could be use to get the job done. Slide the tips of the plier into the 2 small holes and pull open. Took a few tries to get it right.
The parts fitted together well, but there is some slop at the elevator push-pull lever, due to design. The collar which prevents over tightening is a bit longer that the lever so there is some movement. Some added a bit of CA to the collar , i just left it as it is.Before fitting in the TT50 Engine, i did the needle mod which is explained here and here. The TT50's idle needle does not taper down at the end and can cause mid range leaning issues. The needle was chucked into a drill and the tip sanded down.Fan and clutch installed on engine.
Some epoxy to seal the exhaust nipple.
After 3 nights, its starting to look like a heli.

Friday, March 23, 2007

Bling Bling

Had enough of slop in the stock Trex head, and its safer to put in a metal head on the raptor as there were cases of the plastic head exploding on high rpm flights.

After reading so much good reviews on runryder about the kasama head, i couldn't resist and ordered from Kasama is actually made in Thailand so the delivery was quite fast, got the package 3 days after i paypal them. The sales guy, Johan was a nice guy to deal with and he even gave me a discount as i ordered the head, fan and tail combo.
The blings came individually packed in small sealed bags. The quality of the workmanship was good. But alas ,was disappointed when i opened up the packages. Some of the bearings showed signs of brownish rust. I took a pic and emailed Johan about it.
He offered to send me replacements the next day via EMS, while i could send back the parts with rusty bearings at my own time. Cool , now that's customer service. Great guy to deal with. Got the replacements, no rust,I'm happy. Here's how the complete head will look like. Now back to my build...

Sunday, March 18, 2007

Engines 101

It is often the fear of the unknown that prevents people from trying out new things. That flutter in your stomach, that vague discomfort when you get close to the edge of familiarity. That was how i felt when i decided to get a nitro heli. I m not familiar with engines. How do you tune the engine? What fuel to use? and many more questions popped up.

So i asked around and read up on the forums, often i see general replies like " oh use this and this engine with this n this fuel , try turning the high speed needle 5 clicks anti-clockwise, use a hotter glow plug...". They sounded more like trial n error experiences, there must be more science to it. It is important to know exactly how each part works to be able to fly the heli around with confidence and safety. So back to basics, engines 101.

Engines convert energy stored in fuel to mechanical energy to turn the blades through 4 processes characterized by movements of a piston in a cylinder: 1. intake stroke 2. compression stroke 3. power stroke 4. exhaust stroke known as the Otto cycle. 2-strokes engines accomplish the Otto cycle in 2 strokes and are commonly used in helis. Animation below courtesy of Marshall Brain. "How Two-stroke Engines Work". April 01, 2000 (March 17, 2007)

Can refer to here for more details. Or see below
For the titan,I m going to put in a TT50 Pro engine as oppose to the more widely used OS50hyper. Although it maybe harder to tune and less powerful, TT50 gives better fuel economy and more flight time (14mins to 8mins on hyper). It will be lighter on the pockets and serves well as a good beginner engine.
The unfamiliar becomes familiar and it became less daunting after reading up abit. More on tuning later...

Thursday, March 15, 2007


Electronic setup : With specs of speed: .14 sec/60 degrees and Torque: 91.6 oz/in (6.6 kg-cm) the futaba 9252s are chosen for the cyclics as they had good reviews in various forums for their reliability and precise centering. A higher torque but slightly slower 9255 will be use for the collective pitch servo to handle the blades' load. The titan's swash plate is the conventional mechanical mixing using individual servos for each control axis so they don't have to be similar type.

Will be using a 9252 as well for throttle. Ideally the throttle servo should be faster than the collective to reduce bogging on the engine as you want power to increase before the blades load up. Searched the net and found one taiwan website selling them for quite a reasonable price.
The items where ordered from The response time of the sales guy was quite fast, few emails and 4 days later the stuff arrived. This website carries a large variety of rc brands and prices are way cheaper than LHS. For small items shipping is not very expensive as well. Highly recommended if you are looking for futaba, jr, or any tw brands.

With my current skill level, i won't need the gy611 any time soon. Will be using gy401 combo which i got earlier here. The electronics will be powered by a switching BEC so that i can reuse my 3s1p 1200mah lipos. The hyperion TICOOL bec has a switchable 5/6v, 4amps sustained, 5amps burst output and can take up to 10S lipo. With a full digital setup on a 3D flight, the estimated amps drawn is 3amps average with burst up to 4-5amps. A flight will used up around 300mah so each of these lipos should last 2-3tanks. Although more efficient than linear regulators, the draw back of these switch type regulators has been radio noise that the switching can create. The hyperion TICOOL suppose to come with this Noise Elimination Technology, not sure how reliable yet as not much reviews online. It comes with a ferret ring as an additional insurance. Without load, the output was measured to be 5.2v with the 5v jumper, 6.2v with the 6v jumper. With load, it should hold at 5 and 6v respectively. Will update in due course.

Tuesday, March 13, 2007

The kit

Purchased the titan kit from rotor hobby. The box is slightly bigger than the align carry case. Inside are parts neatly packed in smaller packages according to the assembly steps. Flipped through the manual, looks quite comprehensive and clear. Almost ready to start..

Monday, March 12, 2007

Dark side awaits...

The time has come... My current stock trex XL is reaching its flying capability soon unless i upgrade it. It is one of the better mini helis to learn on, i have progressed from heli noob to hovering, forward flight, figure 8, nose-in, stall-turns and recently loops on it. The size is fairly easy to carry around yet much more stable than those micro helis like honeybee, dragonflys which i have seen flyers crashing and spending more than 1/2 of the time at the field doing repairs.

But the trex gets affected by the wind and cant fly far before its hard to judge orientation. Flight time is awefully short with just 2 packs of lipos. A bigger heli with more flight time will be a better platform to progress on. 50size helis seems to be the right size. The choice is then electric or nitro.

I would prefer electric given my EE background and the convenience it offers at the field. Besides plug-n-play, quiet, lipos and brushless motors are more efficient than glow engines in converting energy to power. The power to weight ratio for E-heli surely overwhelms nitro ones. Electric power has arrived and is definitely the way to go in the future. However for now have to look into one very important factor. The moolah, $.

Just compare the energy source alone, for a hard 6 mins 3D flight will need a 10S1p which cost USD400 or SGD600plus. Will need 3-4 packs to fly comfortably long and be satisfied. Each pack properly balanced, charged and used within specs suppose to last up to 200 flights. Can lipos really last that long given the abuse we throw at them?

So far i had 3 packs bloated and 2 packs cant sustain high discharge well even far before they reach their 100th cycles. Not forgetting i have seen bad crashes that totally destroyed lipo packs. Then you have to consider the ESC, motor and higher end chargers which are not cheap. Being electronics, they can get destroyed easily with improper care. And also the numerous hours spent charging the lipos.

Comparing apples to apples, a OS50SX-hyper on 1 tank of 20% nitro can go ard 8mins, each gallon costing S$40 can last 10 tanks so each flight is about S$4. You simply pay as you fly while lipos , you pay in advance but without the insurance of it lasting you 200 flights. The downside is the oil,smoke and loud noise. Some flyers love them though so its subjective.

Glow nitro engines have been around for the last 30-40 years ,its old technology but right now its the most cost effective. New and better lipos are coming out each day and the prices are dropping due to competition from the increasing numbers of manufacturers. It will be soon i hope when the it will be affordable for the majority to fly large electrics.

I did my sums, raptor 50 titan it is..

Thursday, March 08, 2007


How does it feel to be kena arrowed? I meant literally. The smaller field beside our usual flying field at Segar was fenced up recently and it turned out that it was going to be used for archery , presumably by the nearby CC. Today the target boards are up, and they are aligned towards the direction of the flying field.
Kao. I sure do not wish to be at the receiving end of any stray arrows. Even though the distance from the shooting area to the road seems quite far , there are occasional joggers and vehicles passing by. So I thought it will make more sense to align the target boards against the raised slope to make sure the arrows wont hit anything or anyone. Remember Murphy's Law?

Flying shld be done more towards the left side of the field now, just in case our aircrafts become moving targets. Watch your six...

Saturday, March 03, 2007

Decapitated trex

I was moving on to learning loops on the Trex recently after getting a hang of nose-in and stall turns. This morning during one of the tries, the rudder went haywire on top of the loop.I couldn't maintain control.By the time i saw the orientation of the heli, it was coming down fast from about 2 storey high towards the pit inverted!

Holy crap, i pull full negative collective hoping to lift it back up before i flip it back over. The rudder managed to hold ,but it was too low and not enough power to get it back up. I saw it inverted low pass right in front of me before smacking into the ground. The main rotor head snapped off, and surprisingly, the other only damages were the broken blades,bent flybar and main shaft. The main gear is still the same one since day one!
AAR - I think it was because the rudder cant hold the tail when the pitch changes too fast. When i do pitch pumps on idle up, there were times, it simply pirorettes awhile before getting back the tail. Lesson learnt.

The plastic head has quite abit of slop, and will need to upgrade to metal head and a better tail servo like 9650 if i m going to continue progressing with the trex. The metal blings are not cheap and it doesn't seem worth it for a small size heli. Been doing research on the titan for awhile now. Think its about time...