Pitch setup for autorotations

[Crumpet]

I was told by a wise old owl that he always has his throttle hold set so max negative was -6deg so that he could do autos and go straight to bottom of the stick, and if he ever had a motor fail he would just hit it and he would know where he was with everything.

I've been trying with throttle hold doing same pitch as idle up but often have too much/too little pitch as I cant tell exactly where my thumb is, and 2mm movement is about 1 degree lol.

I run +-12 degrees on both my 450 and 700 dfcs

Whats your setups?

[George J]

Same on all flight modes and holds, linear, no confusion that way.

[waveydavey]

Same as George apart from I run a different normal mode and have -4 or so at bottom stick

[coolice]

Hey buddy.

Minus 6 in throttle hold is a little too much, you'd need no more than -4.
This is how I setup my models, you don't need more than -4 in an auto or in normal mode to be honest, so why run it.
Many purpose to keep all flight modes the same, but I have seen this bite people in the butt when they land in normal mode for example and accidentally on closing the throttle during spool down throw in full negative which upsets the model and can cause it to tip over.

The main requirements in any pitch curves is to have the mid to full power points the same, this is assuming a zero centre stick setup, as then when switching flight modes in flight the only change will be increases or decreases in rotor rpm. The latter easily accounted for with subtle collective changes.

Going back to your own setup, how I used to set my negative in TH was to go up high, flick into TH and bottom the stick. If the model fell to fast remove some negative, if it fell to slow give it some more.
At the end of the day setting this negative value will also remove one less job the pilot has to do when learning autos, as the negative value does not need to be feathered. It also avoids stalling the main blades with too much negative in the heat of the moment when your knees are knocking, limiting your rotor rpm for the touch down.
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[Crumpet]

Thanks Coolice,
Well I was running -12 in TH. I'll get it changed. The only reason I was saying -6 was I watched a Curtis Youngblood autorotation class and I thought I remembered him saying -6 is what he used.
I'll change it from -12 at the bottom of the stick to -6 and like you say, if its too much go back from there.

Great reply mate, thanks

Would you use more negative on a smaller model? Obviously the 450 autos like a brick compared to the 700 but not sure if you should use less/more/same negative.

[George J]

For me though Ian and of course I know that you have many more years experience than me, even when learning autos, sometimes you need to bring the model down a bit quicker to land it in front of you and if you've limited your negative you don't then have this option and the heli can over shoot and also once you do get the hang of autos you could have to relearn the collective if you change to a linear pitch curve. Having all holds/modes the same I just think takes out any confusion in the heat of the moment of an engine cut out for example and in that example it doesn't matter what flight mode or hold as everything is the same and you just go straight into an auto without having to think to flick switches.

[coolice]

Thanks Coolice,
Well I was running -12 in TH. I'll get it changed. The only reason I was saying -6 was I watched a Curtis Youngblood autorotation class and I thought I remembered him saying -6 is what he used.
I'll change it from -12 at the bottom of the stick to -6 and like you say, if its too much go back from there.

Great reply mate, thanks

Would you use more negative on a smaller model? Obviously the 450 autos like a brick compared to the 700 but not sure if you should use less/more/same negative.

Hey Buddy.

No worries, you're very welcome.

It's always worth experimenting with the amount of negative pitch available, different blades and even models, will all auto differently. Curtis is probably thinking ahead as with Jonesheli below, by having a few extra degrees to play with should he want to bring the model in a little quicker.

On a smaller model, no I'd probably go with the same -4. As you say with the 450 size machines auto's will be very hit and miss at best, but you don't really need a lot of negative to perform an auto. Ideally we need just enough pitch to make use of the models weight to bring the model down, which at the same time drives the rotors for us and stores energy for the flare.
My own inverted auto's have taught me that too much pitch, in this case positive while the model is coming down inverted, has a negative effect on the remaining head speed at the end of the auto. I've found if I use too much to drop the model quickly as I am going to maybe over-shoot my planned landing spot, once I've flipped out to upright, there isn't much left to play with.
One of the main benefits during auto's I find is the flare and eventual skimming over the air of the model in a slight nose up attitude, in an auto it's known that once you raise the nose of the model rotor rpm increases slightly, combine this with the forward motion and you have an increased amount of air flowing through the underside of the rotors propelling them round.

For me though Ian and of course I know that you have many more years experience than me, even when learning autos, sometimes you need to bring the model down a bit quicker to land it in front of you and if you've limited your negative you don't then have this option and the heli can over shoot and also once you do get the hang of autos you could have to relearn the collective if you change to a linear pitch curve. Having all holds/modes the same I just think takes out any confusion in the heat of the moment of an engine cut out for example and in that example it doesn't matter what flight mode or hold as everything is the same and you just go straight into an auto without having to think to flick switches.

Hey Buddy.

Yes, you are correct once skilled in auto's a good pilot can then utilise the increased negative to change the landing approach. However in the early stages beginners are not looking to land directly in front of them 99% of the time, but just past them to make things easier for the first few goes.
The main thing in my mind really is to allow beginners to concentrate on the approach/decent, with the machine dropping at a nice rate of decent so as not to intimidate or scare them should they inadvertently feed in too much negative.
It is all about conditioning, there are guys in the club who fly the same pitch curve in all flight modes very well, but they have conditioned their brains to this so it becomes second nature with no guess work.
The good thing is once confidence it gained performing autos in general, one can increase the amount of negative available and potentially experiment during the decent to see and feel the effects of this added value.

The other thing that was prevalent in the F3C was that we used to run a little more positive pitch in throttle hold than in any other mode, the addition of an extra degree or two in the hold curve only, really helped that final touch down stage. In normal flight it wasn't needed, but 13~14 at the end of an auto did.

A good tip to remember when auto'ing is, if at the end you feel your head speed has decayed a lot in the final flare before landing, ever so slightly feed in a little forward cyclic. This lifts the rear of the disk upwards slightly away from the boom, thus helping to avoid the dreaded boom strikes.

Another one I use following a less than ideal inverted one, is that instead of feeding in the collective to slow the touch down, gently pump the collective stick. It's difficult to describe, but you are using your available head speed to cushion the landing, but not keeping the positive pitch loads on the rotors, thus extending your hang time.
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[Planehazza]

I don't like having a different curve on hold and idle 2 etc. What if you bailout of an auto and forget you're still at 25% (or 50% negative pitch) collective? That would equate to only -3 degrees in hold, but in idle two, that could be -6 degrees. It's going to plummet if you're not expecting it...

Good post, Ian!

[Crumpet]

only -3 degrees in hold, but in idle two, that could be -6 degrees. It's going to plummet if you're not expecting it...

Good post, Ian!

hadn't thought about that...

Still doable but worth remembering when you kick it alive again

[coolice]

Hey Guys.

Yeah could be a possibility, but if you're bailing out of an auto you're probably already increasing pitch to zero or above and awaiting the rotor rpm to catch up.
90% of failed auto's are going to be in the flare, at which point you are out of the negative pitch values and skimming the air, trying to make the patch :-)

As usual this is very much personal taste and what you get used to perhaps, I limit mine and have stuck with it with no ill effects. Others, mainly those that are newer to the hobby and following current club members setups, opt for the linear in all curves setup and learn that way.
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[Planehazza]

Hey Guys.

Yeah could be a possibility, but if you're bailing out of an auto you're probably already increasing pitch to zero or above and awaiting the rotor rpm to catch up.
90% of failed auto's are going to be in the flare, at which point you are out of the negative pitch values and skimming the air, trying to make the patch :-)

As usual this is very much personal taste and what you get used to perhaps, I limit mine and have stuck with it with no ill effects. Others, mainly those that are newer to the hobby and following current club members setups, opt for the linear in all curves setup and learn that way.
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Very true, and when you bailout, most will panic and instinctively welly up the collective. It's just another one of many 'what ifs'