How To Choose Your First RC Heli
If you’re an absolute beginner you may well be contemplating the purchase of, or will have just bought, a five-channel, 30-size, IC or electric RC helicopter. In truth, having discussed joining a club, seeking advice and choosing a machine that’ll see you from your first tentative hops right through to that coveted BMFA ‘B’ certificate, that’s about as far as we got in the last issue. Tempting though it was, we stopped just shy of spending your money, although we’re about to change all that! In this issue, then, we’re going to set foot in our local model shop, assured of what it is we’re going to buy and determined to leave the store with nothing more and nothing less. So, let’s take a look at what needs to be purchased, and why.
Okay, we’ve established that we’re after a 30-size model, but which one? After all, the shelves are full of ‘em and prices seem to vary quite considerably. There’s no easy answer to this, although on the advice given last month I’d heartily suggest that you talk to the members of your new club and ask for their recommendation. Visit the field on a flying day, take a look around and note the helicopter, engine and radio combinations that seem to be working well for people. That’s probably as good a clue as you’re likely to get, although, for the sake of this series, I’m going to stick my neck out (albeit not very far) and purchase a helicopter that’s been teaching people to fly successfully for what must be nearly a decade. I speak of Thunder Tiger’s market dominating Raptor, a machine that, when introduced, gate-crashed the 30-size helicopter party, stole all the vol-au-vents, then came back to hoovered up the crumbs. No really! Back in 1998 brand new 30-size helicopters weren’t all that common, and with a combination of futuristic looks (which I have to be honest I didn’t much appreciate at the time), a radical design, quality mechanics and, above all, outstanding performance, the Raptor 30 really began to shake the market up a bit. Sales of established competitor designs will undoubtedly have suffered as a result and it’s no surprise that not too long after, some of the more established brands (Hirobo, Kyosho and JR, for example) were seen to introduce machines that were quickly labelled by the model press as would-be ‘Raptor beaters’. Anyway, I think it’s fair to say that at this particular moment in time 30-size helicopters took a small step forward in terms of the quality, specification and performance of the available hardware, indeed some would argue that we have the Thunder Tiger Raptor to thank for it.
Now, the current version of the Raptor 30 is the V2 (version 2), this being sold in two forms, i.e. as a self-assemble kit or as an ARTF (pre-built) with Thunder Tiger 39 installed. Time and disposable income will dictate which you choose, although I have to say I’m a great believer in building from a kit for the following reasons:
If you fabricate the model yourself you’ll know it inside out and will be far better placed to repair it when the need arises.
In my experience, factory assembled helicopter kits need a very thorough check prior to flight. Alas, certain items (clutch assembly, for example) are impossible to inspect without stripping the machine down, which, of course, defeats the object of buying an ARTF.
Building a model helicopter from a kit is an exercise in Meccano modelling for grown-ups. In other words, it’s great fun and hugely satisfying. Why wouldn’t you?
So, given the choice, I’d build a helicopter every time and, using our Raptor 30 V2, this is precisely what we’re going to do over the course of the next few issues.
Okay, we’ve cast our eye around the shop picked a Raptor 30 kit and stuck it on the counter. Best we find an engine to go with it!
Actually, this is a bit of a ‘no brainer’ when you take a few very simple rules of thumb into account. Let’s start with reliability. Without this essential requirement you can forget all about enjoying the learning process. Instead, you can look forward to flying sessions filled with frustration and needless fiddling. An engine that won’t start, is difficult to tune, or runs badly, will make a misery of a Sunday morning session, yet, for the sake of spending another £10 or £20 on a quality item, it needn’t be that way. My advice here, then, is to buy the best you can afford.
The next requirement is the engine’s suitability for its intended purpose. Thunder Tiger recommend a .39cu. in. two-stroke, suggesting that this will suit learners and aerobatic hopefuls alike. Given as much, it really would be silly to buy something different! Why? Well, a larger engine is likely over-stress the mechanics and may not even fit the motor mount or clutch assembly, whilst a smaller one will undoubtedly struggle to make the machine perform.
To sum up, we need a brand new, quality engine of, say, .36 – .39cu. in. capacity that’s designed to fit the model. Fortunately, Thunder Tiger (TT) engines have a superb reputation in the marketplace and since the recommended item for our Raptor is a TT Pro 39H, that’s what we’re going to buy. If you go for a suitable alternative (O.S. 37 for example), make a note that the hole spacings in the mounting lugs of the engine must be 15mm apart, i.e. to suit the tapped holes in the metal motor mount that’s supplied in the Raptor kit.
Incidentally, there is one final consideration here: The TT 39 doesn’t come with a silencer, and we’re going to need one. Again, the amount of pennies you have available will play a large part in the selection process, although I have to say, silence is golden as far as I’m concerned and the quieter the muffler the better. In this respect I’ve always been hugely impressed with the range of silencers manufactured by Zimmermann and would recommend them to anyone. Trust me, if you fit one of these your helicopter will hum like a sewing machine and it’ll be far more pleasant to fly. Sell your grandmother if you must, but don’t skimp on silencing.
And so to the next most important consideration. As a beginner your first radio purchase is quite an important one, although, to be honest it’s not something you can really get wrong. Buy a heli’ compatible RC set manufactured by one of the popular brands (Futaba, JR, Hitec, Multiplex, Spektrum, Graupner) and you’ll have a system that’ll comfortably see you through the learning process and well into the future. Radio control equipment is cheap these days, (Far Eastern manufacturing has seen to that) and, since even the top brands are so relatively inexpensive you’d be silly to buy anything else. That said, do note the following considerations:
Make sure you buy a computer radio. Ridiculously cheap, they make life so much easier whilst many (not all) helicopters depend on the mixing functions provided.
Though generally very intuitive, the programming of a computer radio can be a little confusing at first. This being the case, try to select one that’s known to, or used by, your clubmates.
35MHz or 2.4GHz? Assuming this is your first radio purchase and that you don’t already own a 35MHz transmitter and a collection of receivers, my recommendation would be 2.4GHz.
Taking my own advice I opted for one of the most popular 2.4GHz beginners’ sets on the market. Futaba’s 6EX 2.4 has a street price of about £160 and, if you ask me, it’s a steal! Offering six channels, six model memories, five-point pitch and throttle curves (we’ll explain about these in a future article), CCPM mixing, plus a host of other features, it’s packaged with four standard servos, a 7-channel receiver, charger and 700mAh NiCad. All but the NiCad, which is arguably a bit low in capacity for comfort, is suitable for our purpose, although do note that we’ll need to buy a fifth servo, for the gyro.
Gyro And Tail Servo
Untamed, the tail rotor control of a model helicopter is quite a ferocious thing that’s almost impossible for regular humans (like you and me) to control. Accordingly, gyros have been developed to dampen the effect of the tail rotor and make our helicopter significantly easier to handle. We’ll discuss how they do this in a future issue, however, for now we need only concern ourselves with the fact that a gyro is on our shopping list. So, which to buy?
As with any item of equipment for model helicopters the variety and choice is almost mind-boggling. That said, as a beginner we needn’t spend a fortune here, indeed a £50 job will do us proud. Try to avoid those that boast a ‘heading hold’ feature, or indeed anything that has its ‘gain’ adjusted at the transmitter. Heading hold is another feature that we needn’t concern ourselves with just yet, and whilst a Tx adjustable gain is all very nice, most budget transmitters don’t offer the facility which, in turn, will make the gyro incompatible with our system. My suggestion? Get yourself a Futaba G191 (or something similar) and make sure the gain is adjustable from the outside, typically using a small screwdriver.
Now then, since you’ve saved a few pennies on our gyro I’d suggest you spend them on a servo to go with it, although we’re not going to buy a standard unit like the four supplied with the 6EX. Here’s why: When plugged in and operational the gyro will detect any unwanted movement of the tail (from, say, a gust of wind) and will apply a corrective control response (via the tail servo) to counteract it. The faster it does this the better, and since the whole gyro / servo response system will only be as quick as the slowest item in the chain, i.e. the servo, it follows that we need the fastest unit we can afford. Typically, as far as servos are concerned, speed comes at a price and so we’ll probably have to make a compromise. That said, any standard size unit with a speed of 0.21 seconds over 60¡ of travel will do just fine. Ultimately, try not to get too hung up on this with your first model for if it’s all you have, a standard servo will also be okay, although your tail rotor control will be marginally less precise. Not that you’ll notice mind, for as a beginner you’ll have no benchmark to measure it against. Once again, you’ll just have to trust me!
Well, that’s the most important stuff bought, although, clearly, you’re going to need some other bits to help you assemble and fly your model. We’ll deal with items of field equipment when we get a little closer to flying our Raptor, however before you start building, and preferably before you leave the shop, it might be worth considering the following essentials:
- A hex driver set. As it says, a set of four hexagonal (Allen) drivers in the following sizes: 1.5, 2, 2.5 and 3mm.
- Thread locking compound. Don’t even contemplate building a helicopter without a tube of blue ‘thread lock’ and red ‘stud lock’ by your side.
- A pair of ball link pliers for easy fitting and removal of… er… ball links!
- A pitch gauge for setting the correct rotor blade pitch angles before flight.
- A ball link driver for saving your pinkies when threading ball links onto pushrods.
I’m assuming you’ve already got basic tools such as a set of cross-head and flat-head screwdrivers, needle nose pliers and the like, so that’s probably enough to be buying for the time being. Exciting eh? Incidentally, in case you’re wondering, here’s a rough idea of how your shopping bill should look:
- Raptor 30 kit £180.00
- TT Pro 39H engine £80.00
- Zimmermann muffler £60.00
- Futaba 6EX radio set £160.00
- Futaba G191 gyro £50.00
- Futaba S3152 tail servo £25.00
- Hex driver set £10.00
- Thread lock £2.00
- Ball link pliers £10.00
- Pitch gauge £10.00
- Ball link driver £5.00
By my reckoning that comes to a not inconsiderable £592. Mind you, when you sit back and look at the precision engineering and electronic wizardry you’ve got for our money, it’s a very good deal indeed!
GLOSSARY OF TERMS
ARTF: Almost Ready to Fly – a model that is between 70% and 90% pre-assembled.
BMFA: British Model Flying Association – the governing body for model flying in the UK.
B Certificate: A certificate that’s issued by the BMFA after undergoing (and passing!) a test of piloting competence.
Heading Hold: A facility of a mid- to high-end gyro that allows the pilot to lock the tail on a certain heading and prevent it from swinging. It’s a feature used primarily when flying aerobatics.
Tx: An common abbreviation for transmitter