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**Steve** · 25-08-2007, 11:09 PM

Originally posted by robertwo View Post

Couple of quick questions:

What's the ideal head speed ona Raptor 50?
Currently have a GV-1 Govenor and it's set to 1470 RPM. Main reason for asking is that I'm just starting out and trying to learn to hover and it seems a lot easier with the govenor turned off on the TX. Was thinking it should be more aroung the 1600-1700 RPM, is this correct?
Centre of gravity - How much difference does this make to stability of heli? If I hold the heli on it's side so it can pivot around on the head, the nose drops like a stone.
Pitch settings - currently have something like -4 to +9 (maybe +10). The heli does not hover or lift off at mid stick, it's about two "lines" past centre stick before it lifts off and needs to stay about the same to hover.

Read some threads that suggest should have about +5 at centre stick, is this correct, and if so how to I obtain this? do i need to adjust the linkage length between the servo and 'pitch contol arm'?
One last thing on pitch, is using the built-in pitch gauge on the frame ok for a beginner, or should I be doing this another way? I do have a pitch guage but can't quite gets to grips with it!

Head speed - if you up it to about 1700 then the heli will become much more responsive and also much more stable. However, more 'go' can get you into trouble quicker than 'less' go. The 3D boys typically run 50 head speeds at about 2000, but there's no need for this as a beginner.

C of G - Build the heli as per the instructions and it won't be far out. It should ideally be bang on the main shaft, but again, as a beginner, you're unlikely to really notice any problems, as you won't know any different. Nose heavy is better than tail heavy.

For learning, your pitch curve should be about -3/-4 at the bottom, +5.5 in the middle and +10 at the top. Set your pitch curve in idel up one to these settings, and then adjust your throttle curve at the field so that it does hover at middle stick. Don't adjust your pitch curve once you've got these values - just match the throttle to the given pitch settings.

Built-in pitch gauge - is handy I suppose, but its accuracy depends on how accurately you made up all your push rods. A proper pitch gauge is a worth-while investment. Some will say you don't need one as there are 'other' ways of setting the pitch on your heli, but trust me, a pitch gauge is the easiest, and will give you the confidence that the settings are correct.

**skatefreak** · 26-08-2007, 12:52 AM

Hey,
Just a note on the headspeed.
Upping the headspeed will indeed make the helicopter more responsive and a little more stable but for learning i would recomend the lower headspeed.
This is mainly because it will soften the controls making the helictoper more docile, it will be a lot less intimidating, your fuel/dampners will go further and also back in the day i used to fly an R30 with a headspeed around 1100, had a pair of JP carbon blades survive 8-9 fairly good crashes...
When the headspeed goes up the crash costs can take a significant hike!
Once you get into forward flight and such i would recomend upping the headspeed, but untill your flying it about comfortably you should be fine at 1450

Just another mention, the raptors arnt to bad but you will proberbly notice a slight tendancy for the heli to wobble a touch in forward flight, this is only due to the low headspeed and will go away as you up the rpm

The nose heavy situation can make trimming the helicopter out a little confusing, with a little wind you have to find the mid point in drift with the wind nose in/tail in to the wind, add a weight imballance and you will find it will have a tendancy to drift in that direction....
Not to much of a problem though just trim it out for now

on the subject of curves its all down to personal preferance,
most people start with hover at midstick because it makes the collective less sensitive and therefore easier to manage when you start, but then the counter argument is if you want to progress into 3D you will then have to get used to mid stick at 0 degrees, if your not having much trouble with the current pitch setup maybe you might want to stick with it as it will save you having to re-learn the collective stick somewhat, but if you are finding it a little sensitive you can ajust the collective arm link so that you have hover at mid stick (servo at 90 degrees here would be advantagous for hovering training, when you return to center stick = 0 derees this is where you will want the servo horn to be at 90 degrees ) and maybe -4 low stick and + 10 as mentioned below

The built in pitch gauge relies on all the links being at the specified lengths, sometimes this will not be the case (if you know someone with a pitch gauge maybe see if you can varify the inbuilt pitch gauge is accurate?), i would deffinatly recomend a blade/flybar pitch gauge though...

You engine, it sounds like its deffinatly running rich, this is not a bad thing though, or at least its not going to dammage your engine as if it were running lean.
General pointers for how well the engine is running are:

Smoke: (Applies mostly to an engine that has been run in and you are familiar with the general amount of smoke produced).
The more smoke you get the richer the engine is running, more fuel than air = less complete combustion and therefore a lower running tempterate, if less smoke than usual is produced that can be due to a lean condition where more complete combusion takes place and leads to the engine running hotter causing exessive ware to the engine components, heat fatuige and if overheated the engine will stop running.

Temperature:
Measure the temperature on the backplate of the engine, a rough indication can be taken from the amount of time you can comfortable keep your finger on the backplate, generally accepted at around 6-9 seconds.

Throttle responce:
When running rich the engine will be less reliable at idle and slow to pick up rpm as appose to in a lean condition the idle will seem very reliable and the throttle response will be a lot quicker, one tell tale indication to a lean idle is the rpm may not stay very consistant and is quiet noticable...

Pinch Test:
With the engine running at idle, pinch the fuel line and it should take (if memory serves me right) about 5 seconds for the engine to die, and longer and its richer, any sooner and its leaner.

General running:
Usually if an engine is running *Racy*, high inconsistant idle and generally putting out more ommph than you would extect then i would check the engine temp and watch the smoke, these little nitro engines put out a much heaftier punch when run lean, its just a shame that it will kill you engine to run it lean for very long as they cant handle the higher temps.

Using the above should get you started on engine tuning, once you get to know your engine you wont find it so daunting

The high and low needle issue.
The highend needle effects the fuel mixture in the higher rpm and low end needle deals with the low end mixture.
http://www.osengines.com/engines/osmg1951-inset-2.jpg
If you look there you can see the flat screw head at the top of the carb, this is factory set and you shouldnt need to ajust it,
it only effects the mixture through 180 degrees of movment and is rather sensitive, there is lots of info on the best setting here but it should be fine

Hope all goes well and enjoy the hobby...
It will soon consume you *grins*

Best regards

-Jvr

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'Couple' of beginner questions

'Couple' of beginner questions

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