Head Speed

[fernandezsraptor]

Ok I know the effects of a lower head speed to a higher head speed in relation to the Heli's
reaction time, my question is over reving the engine, I have a 30v2 raptor with a full metal head and a metal swash plate
powered by a OS 37SZ ringed engine, the rest is stock . What is a good higher head speed thats safe on engine rpm. but good quick reaction on the Heli? the engine runs great but I just want to be on the safe side, If there's one

[Motions]

On the Raptor 30 and 50, you shouldn't go above 2000 RPM. This does depend on the blades your running also. Only run higher head speeds if your using carbon or composite blades.

Generally speaking, you should not exceed 2000 RPM with a 30-class helicopter, or 1900 RPM with a 60-class helicopter. There are exceptions to every rule, but generally speaking you'll be better off if you stay within these guidelines. When a rotor head fails, the entire helicopter is usually destroyed. Not just damaged, but destroyed beyond repair. In addition, many pieces typically fly in many directions, posing a safety hazard for everyone within 50 yards or more.

If you're using a tuned pipe, your engine will probably only be happy within a narrow RPM range. This complicates things a bit. If you're using any other sort of muffler, you can probably run the engine happily over a wider RPM range.

These guidelines should help determine what head speed is best for each pilot:
For precise hovering or scale flying, 1500 is a good place to start.
For cruising around, the usual range is 1600-1750.
For aggressive aerobatics, the usual range is 1750-1850 for 60s and 1850 to 2000 for 30s.

[AaronS]

good advice Motions, but I would like to add one little thing. the question was about the engine RPM, and you are correct about the headspeed. fernandezsraptor, the reason Motions goes into the headspeed issue and does not address the engine RPM directly is becasue the engine is not going to over rev befroe the rotor head. The gearing in a particular application is set up for the engine RPM range. in most cases, the rotor head is going to run into an overspeed issue before the engine.

[Motions]

Thanks Aaron. I know the original question was about engine RPM but on helis, 98% of the time engine RPM is measured in relation to headspeed as you can't measure engine RPM unless you use an optical or magnetic sensor. On plankers you can just tach the prop.

Once you know your gear ratio, you can determine engine RPM by the head speed.

[fernandezsraptor]

Thank you All

Great advice, I have the stock wood blades, no carbin for now I am still in the learning stage with Heli's and a Mavrikk muffler, I have been flying nitro airplanes for 20yrs now and got into Heli's about a year ago, ok sorry back to the question, what are signs of over spinning the rotor head, I know parts can come off, posting a hazord but will there be blade flutter or a risk of stalling the blades out?

and thank you again for all the help.

And most important Great Magazine.

[Motions]

I have the stock wood blades, no carbin for now...
You should definitely keep the head speed below 1700-1750. I've seen too many woodies disintegrate at high head speeds. There really is no way to know what speed your running without a tach. If you don't want the expense right now, I urge you to find someone in your area that has one.