Hello, I want to start practicing autorotations. I just have one question, is it the same feeling to autorotate with 2,500RPM than to do it with 3000RPM??? I ask that because I have a 3500kv motor with 11th pinion, so, I am not getting high RPM. I tried autorotation today and when giving negative -4, I saw the heli came down too fast , so, I don't know if it's because my RPM were too low or I have to practice more, I guess the second was the problem but I was curious about the RPM issue. thanks

Well considering you autorotate with the motor off, I don't see how your powered up RPMs would matter? You are hitting throttle hold to initiate your auto's yes?

Skarn

matador_24 , hey its been a while since i heard from you, hope all is well. You know the best way i found to practice is get high, have the heli at a 9 or 3 o'clock position, make sure you are in forward speed then dump the throttle. If you have a couple of neg degree on pitch it will fall quite fast but that's ok, keeping the forward speed is a must. As you get close to the ground start pulling back on the cyclic until the heli comes to a stops which in the ideal word would be just high enough that the tail doesn't strike the ground. Once stopped and in combination of stopping increase pitch AND throttle to hover. At this stage it is important to not hit the throttle hold as you will want to recover to hover with power. Once the technique is mastered you can then hit the throttle hold. They are a little scary to start with as it will fall fast, but if you do it every pack it will become easy in time and no problem at all.

The rpm of the blades in an auto situation is determined by the negative degree of pitch on blades and the speed the heli is falling, not initial rpm.

Hello Skarn, yes, I hit the throttle hold. the auto wasn't that bad It's just that I saw it came down too fast and I was wondering if it's because I just get about 2,500RPM of my set up.

Hello heliaction, I am pretty good, thanks for asking. It's just that I haven't had much time to fly and I haven't had any issue with my t-rex, happy with it! I hope you are ok too.
Thanks for your answer, it's interesting..... just something, all what you explain is with the motor ON, right???? and when I master the auto then I can hit the throttle hold, is that right???? how many degrees should I give while coming down? -4 or more???
I remember once I hit the throttle hold to try an auto and then I hit it ON again and the tail drifted very fast and I almost crash... is that normal????? (I have HH mode in every mode, including Autorotation switch)

A 450 size heli will auto but they auto like a home sick lawn dart.

I don't see how you could practice auto's with the motor still on.

I would watch the Finless video he made on auto's with the TREX 450. He makes it look so easy.

His method is what Heliaction posted...he get's forward speed up around 20 feet up or higher than hits throttle hold.

You could practice on the sim first.

Skarn

Hi guys,
If you want to learn how to do autos then a 450 size heli is not the best way to start. The blade diameter is half that of a 50 size Heli, which works out at a quater of the energy (inertia), making an auto sooo much harder. If you want to try to auto I strongly suggest you fit a non driven tail drive as this will give you a little help as you dont waste energy on the tail, its not required in an auto unless you are doing aerobatics on the way down. If I ever do that it is an accident in the making and everyone in the area should leg it fast.
Bigger helis have more energy in the rotor system and are therefore better suited to autos.
Some random thoughts for you, if you suddenly drop your throttle immedately after hitting thro hold you will drive the heli down as your blade RPMs drop, and have to recover this energy in the decent. You do want to get to neg pitch quickly, just experiment with how quickly. The higher your RPM at the start of the auto the better as you have more energy 'in the bag' at the beginning. Each heli has a -ve pitch value that it works best at, I have heard -4deg suggested as a starting point.
And, a little wind and forward speed are really important on a small heli like the trex as you can use this energy at the bottom during the flare, even if the rotor RPMs are not the greatest, this will cushion the final part of the landing. A trex 450 with a driven tail on a calm day with little to no forward speed can auto, but only I would suggest by a top heli pilot. I personally would wreck mine in such conditions, no question about it.
I agree with Skarn, practice on the sim first. I did hundreds, if not into the thousands on the sim before I tried one for real on my Titan. Result, happy me and undamaged heli. But remember, you will only have 25 percent of the energy that I have with my Titan.
Whatever you decide, good luck, I hope it works out well.

Cheers,

Big feet , you may speak some truth about a 450 size heli, however i and loads of others aren't going to buy a bigger heli just to auto. FWW my TRex auto very well, i cant compare to a bigger heli (except full scale lol), but im in full control and i don't find it hard.

matador when you say motor is on well if the throttle stick is all the way down the motor is off isnt it???i am mearly suggesting a powered recovery instead of full auto to the deck. It might save some damage, but if you already doing it then go hard. -4 pitch is a good place to start. As for your tail drift that can be normal if your head speed is low.

keep up the good work

i always thought and do it with flat blades, or enough to keep it (the heli) and the speed up at the same time. but of course you might only be able to do that with big helis. like my 600

The lighter the rotor system the less inertia so with a 450 you need a pretty good bit of negative pitch to keep some rotor rpms up.

Try it with flat pitch and you will find out what a blade stop auto looks like.

Hi heliaction,
I totally agree that people are not going to get a 50 size heli just to auto, for a number of possible reasons, cost, noise, availability of a flying site, etc. My intention was simply to highlight the issues with a small heli when an auto is attempted. I have seen them auto'ed both successfully and, errr, not so successfully. I have not as of yet attempted to auto my 450 as I have seen better pilots than me try it and get it wrong. In reality an electric heli should not be at much risk of a power failure compaired to a nitro bird. After years with planes I know only too well that nitro engines cut given the slightest reason. If you use a timer you should never be forced into an auto on a 450, unless the motor or esc fail, and hopefully this is a very very rare event.
Are autos fun, yes. Do I like to do them on the Titan? again yes. Has the Titan been crashed in an auto? no. Chances of my 450 crashing in an auto? high. Fun? errrr, unlikely if I break it.
I'm impressed that you auto your 450, I hope to try it on mine someday, but not until I fit a non driven tail and get more stick time on her. She has only about 20 flights on her at present.

Happy landings,

I force autoed my 600, but it was pilot error. I forgot to charge the BEC battery, so the motor and the controling capabilities died. So it really wasnt an auto, more like a run away from the falling helicopter overhead kind of thing lol

hi bigfeet, i have a question, how do you make a non-driven tail on a trex 450? the autorotation gear is bolted to the main mast.

In the Ray's Electric and CCPM series he modifies the Trex450 for a non-driven tail and it autos quite well.

how bout a link to the thread? this has got my curiosity peaked.

Its not a thread, its a DVD series, its reviewed in the magazine section and available here http://www.rayshelitech.com

450s can be auto'ed. There are tons of videos on the net of 450s being auto'ed. On the Helifreak forum, one of the posters (Finless) who is regarded as a guru when it comes to most things helicopter, posted a video of him performing autorotations with a 450. The secret is getting some forward speed to help the rotors maintain their momentum. With carbon fiber blades, auto become much easier to do.