On shooting themselves in the foot
Why competing helis don't offer where to mount a mixture servo remains a mystery, but interfering with competitors shooting themselves in the foot would be dumb. Especially when they're spotting you a sweet advantage!
Saying if they want to promote the claim pilots can feel 2oz in a 600-class model, that's fine by us – but we're not buying – not even if the world's best pilot says so! Why not? Simple, because it still wouldn't trump what using a servo in flight to adjust the air/fuel mixture brings to the game.
It not only saves time, but maybe money, too! Time, because landing over and over again to fine tune the engine is time you're not having fun. Money, because too-lean can cost you an engine, whilst too-rich can lead to an engine flaming out unexpectedly (and if you're unlucky, it happens too low to autorotate).
Worse (if you're really unlucky), it costs you an engine and you crash! So is gaining the ability to adjust your engine's fuel mixture on the fly really worth it? No-brainer!
Emergency adjustments
But there's more to it than just convenience. What if you have the mixture dialed in perfectly, but after refueling, you lift into a hover and as you dip the nose to dart off on another sortie, the engine RPM begins screaming as it goes too lean to support reliable combustion? The likely cause is forgetting to replace the pressure line on the muffler. Believe me, this may constitute an emergency situation!
The emergency exists for two reasons – both usually related to money. If you have enough altitude, then maybe you're lucky and you cut throttle and get the model back on the ground without engine damage. Point being, if an engine goes lean for too long, then it's subject to overheating and thus, being damaged. This means sending it out for repair, or buying engine repair parts, and tearing it down to rebuild, yourself. Worst case, you crash the model and screw up the engine so now you're staring down repairs amounting to a car payment – argh!
Note; if after slipping the pressure-line back on, you go to fire up the engine, but it won't start (or does, but idles poorly), then the answer is likely the glow plug element was damaged. In short, there's no such thing as an innocuous lean engine-run because it can easily cost you a glow plug – and they don't give those away, right?
ProTip: consider installing a new plug after a lean run to avoid future issues, but better still, avoid it happening to begin with!
Installation
The how-to for avoiding all the nonsense, is easy. With a mixture servo installed, P6 owners can just give the knob on the transmitter a twist to richen the mix, then come back in for landing, slip the pressure line back into place, readjust the mix, and go!
Installation is a doodle because unlike other models, a P6 gives you where to mount up to eight servos instead of five! So after mounting 3 for cyclic, another for tail rotor, plus one for throttle . . . this leaves where to mount another servo for mixture control.
Basically, slip the servo into place, and holding it in position with finger pressure, drive the four screws home to secure it. These into existing holes, of course. It doesn't get any easier!
Next, attach a spare servo arm to the end of the needle valve (easy because it's already drilled and tapped M3 from the factory). Then after ginning up a linkage, Bob's your uncle!
To finish this relatively easy job of installing a mixture control servo in your helicopter, just plug the servo lead into a spare channel, and you're done – easy peasy! Finally, and as usual, at the transmitter adjust direction of rotation, the neutral position, and the end points for the channel you elected to use.
Last thing, while sliders are OK as a means of variable adjustment, a knob is best in our opinion. This, because it's the same-same motion used for tweaking the needle at the engine!
Wrap up
Why don't we include a mixture servo with the avionics bundles? In part because we sell avionic packages to folks with other brands of models (no place to install a mixture servo). But also, because – believe it, or not – lacking an in-flight mixture servo leads owners of other brands to believe nobody need one (strange but true).
Anyway, in light of the convenience in-flight mixture adjust brings to the game, it's our view this is either sour grapes (because their model doesn't offer the benefit), or the old saw about – you can lead a horse to water, but you can't make it drink. Of course, since we're not about forcing anybody to do anything, it's always your call regarding doing what's best for you!
Perfect mixture just listening to what an engine wants – without guessing? Priceless!
Summary
A mixture servo is more than a mere convenience because it can save you time plus money. As for why other manufacturer don't think it's important? We honestly don't know, but that's their lookout! So unless you fancy taking added risk with your $400 engine, or landing over and over again to make minute mixture adjustments, then this is better . . . and it's not even close!
