Sloping Off - March 2006
Twister CP V2
by David Morgan
Christmas was just a couple of weeks away, and I was asked what I wanted from Santa?! I knew - my first helicopter! Now what should it be? It needed to be relatively cheap (because gliders and electric power are my main interests and Santa would actually be sending ME the bill eventually!). I needed it to be fairly stable for me to learn on but capable of decent performance (in the hope it survives my learning curve!) I didn’t want it to have a messy engine (did I already mention I like electric power?!) and it should require little/ no assembly time (I wanted to fly it, not build it at first, anyway). So I decided to buy (sorry, ask Santa for) a Century Hummingbird (no, wait... not finished yet!).
Off I went to Channel 4 Models to outline my plans to John (and Brian, who was there at the time). The plot thickened as we got into a discussion about fixed pitch v. collective pitch then John made a sales pitch (boom! boom!). Not really, of course (helpful chap, John) he just showed me the new, recently price-reduced, Twister CP V2. It was collective pitch (Oooh! Aahh!) It came with radio Tx (Mode II, although convertible to Mode I if you wish) and two (yes, TWO!) LiPo battery packs (useful) and had carbon-fibre blades (pretty!). It also includes a balancing charger for the LiPo’s (just needs a 12 volt supply/ battery for the input) and even comes complete with eight dry-cells for the Tx! It was under £200 and I bought it there and then (on Santa’s behalf, of course!).
So - Question: What do I think of the Twister Cp V2? Answer: I'm really pleased with it. I'm told that although collective pitch is a bit harder to master to begin with (although opinions seem to vary, even on this!) it's much better in the long run. I read the little instruction booklet, watched the enclosed video (on DVD) and waited for Oakmead... (well, I did charge the batteries and spin the rotors up a few times just to check everything worked). I also bought a training undercarriage (you know, the ping-pong ball kebabs) and (having read some posts on the Internet) spent a few pennies on heat-sinks for the main and tail motors (the heat-sinks are a push-fit and apparently greatly prolong the motor life particularly the tiny tail motor). More on modifications later...
I’ll spare you the detail of the excitements of my first outing at Oakmead I DID experience a bit of radio “glitching”, but put this down to the number of adjacent transmitters/ building (metal) structure/ less than optimum aerial layout (since altered) and wiring runs adjacent to motors (now slightly re-routed). It also resulted in the main rotor “biting” me and Trevor Hewson who was kindly helping me set up (though that was mostly my fault sorry, Trevor!) fortunately only “warning shots” with no real injury in either case. Extensive testing since, after the modifications mentioned, appears to indicate that the problem is (hopefully!) solved and all is now well time will tell...
Mention of Trevor also leads me to the most important bit how does it fly? Well, having seen Trevor flying it and smoothly hovering and manoeuvring it (thank you, Trevor!), I’m very pleased with its performance. Trevor mentioned that it’s quite sensitive (even with the flybar weights fully out) and could possibly do with moving the servo linkages in by one hole to lessen control movement while I’m learning. I don’t think I can use my Futaba computer Tx (to get rate adjustment), which was another suggestion, since the supplied transmitter communicates with the 4-in-1 unit (Receiver, Mixer, Speed-Control and Gyro) using Cyclic/ Collective Pitch Mixing (CCPM) system encoding but I haven’t totally ruled that out (would make setting the rates up interesting, though!). Trevor also commented (positively) on the speed of the Twister’s response to the controls. The video clip on the DVD that comes with it also shows the Twister in a good light (well it would do, wouldn’t it!?) and I look forward to a lot of fun trying to realise its full potential.
One significant modification I’ve made was to change from the (x8) dry-cells which power the Tx. I noticed that there is a charging socket already fitted to the Tx (so rechargeable individual cells can easily be substituted). However, I don’t like the potential for problems with this arrangement, so decided to replace with a standard 9.6V 700mAh “flat-pack” NiCd battery (I had a spare one anyway, having removed it from my Futaba radio to replace with 2200mAh NiMH battery). The alteration was simple: slide out the metal connectors in the battery compartment (no longer needed), undo four screws holding the back on and carefully ease away the case back. (It’s still attached by wires to two switches, so go easy!) I unplugged the power cable and remaining +ve and ve battery connectors and snipped them off. I soldered on (and sleeved with heatshrink tubing) the leads from a Futaba power connector (socket) to match the plug on my battery pack and re-assembled. Easy! I would really recommend this modification as, for very little effort (provided you can solder!) and little money, you can cut down the number of interconnects, which must make for better reliability.
In passing, one thing to be aware of (almost caught me out) is that the charging socket IS connected; it's just that my Futaba charger has the tip (inner) +ve, while the Twister Tx charge socket needs the tip connector for the charger (inner) to be -ve (Doh!). I just used a cheap “selectable” power adapter (available from Maplins etc.) to give a 12v output, with correct polarity, for charging.
The other purchase I’ve made was for a cable to interface between the TX and serial port on a computer to use the (free) flight simulator FMS (can be downloaded from the Internet, but was also included on a CD that came with the cable). The cable has a PIC microprocessor built in, and plugs into the “buddy” socket on the Tx allowing this (with crystal removed!) to control the virtual helicopters (or fixed wing power/ gliders) for practice without pain/ cost! The cable (and software) is about £15.
In conclusion, I think the Twister is good fun and great value for money. As I’ve taken to practicing indoors occasionally I’ve bought some spare blades and bits “just in case” (I think they’ll be needed.!) and now I’m off to do some hovering (What’s that dear? No, I said “hoovering” that’s the noise you can hear...)
Happy Flying!
