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Old 10-06-2010, 09:59 AM   #1
RĒzĒ
 

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Default How-To: Autos

Today I want to talk about Autos. They are one of those deceptive things that at first seems really hard, but then they seem really easy, but to do really good ones, they become really hard again

I want to share what I've recently learned in the last couple of weeks. It boils down to this one simple statement: Even at negative pitch you can pull out of a dive or FFF.

I started to notice that if I was flying forward at a decent pace, I could pull up and gain altitude even when I was at zero pitch or even less than zero pitch. This is not an obvious behavior about flying helis. With that knowledge in hand I started practicing and right off the bat I started pulling off some near perfect autos.
  1. Start off high and away
  2. Get the heli moving forward towards the direction of your landing zone.
  3. When it gets moving pitch the nose down a bit, put the collective at a few degrees negative pitch (around 1 white tick mark below center), and then hit the throttle hold. If doing an inverted auto you would use a few degrees of positive pitch...
  4. Come down about a 45 degree slope. you will be picking up more speed from the descent
  5. As you near your target gently pull up and begin to flair upwards. Do NOT touch the collective. Leave it at a couple degrees negative pitch.
  6. As the heli pulls out the the dive the head will spin up very fast. So fast you will have quite a lot of hovering time. At this point maneuvar the heli around to land in your spot.
  7. It's generally a good idea to swing the tail around on your final approach (after your flair) so that you are flying backwards a little bit to help keep you from hitting the tail blades when you land.
Doing this you will have all sorts of time to place your landing wherever you want. You will need practice to get the hang of where to start the dive, how high, how far away, how fast, what approach slope, etc... but now at least you should be armed with some knowledge on how to get the head to spin up really fast. Even inverted autos start to get easy quickly once you get the mechanics down on how to flair out of an inverted dive.

So I hope that helps some people. It was definately one of those click moments for me. I always avoided learining autos as I didn't really understand what went into doing one properly. Now that I understand them much better, autos are finally easy again
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Old 10-06-2010, 11:47 PM   #2
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+1. Nice write up. I was fortunate and was able to be a bystander at Todd and Matt's flight school this year in Snohomish, WA. I was able to stand behind a buddy of mine taking the class and was quite shocked when Todd told my buddy to auto at midstick (it was a 700). I would never had thought it possible until I saw it with my own two eyes. He never went negative and was able to keep the headspeed up by finding that sweet spot with the angle of attack. Just goes to show that VERY LITTLE negative pitch is needed.
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Old 10-10-2010, 08:47 PM   #3
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Hmm, are you suggesting not to use positive pitch at all, not even just before touching the skids?
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Old 10-10-2010, 08:50 PM   #4
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No no. Of course you have to use positive pitch to flare at the end. It was more to point out how little negative pitch is actually needed to keep the headspeed up UNTIL the flare.
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Old 10-13-2010, 04:52 AM   #5
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Hi nwmtech,

I think whilst flare, we have to keep the blade pitch in negative angle as RaZa says in his instruction. This converts forward momentum into the additional speed for main blade.

Once the model stops moving forward, we should have good rotation inertia of blade then use this inertia power to land model in the spot with just enough positive pitch angle.
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Old 10-21-2010, 09:52 PM   #6
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Default video needed

please post a auto video
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Old 10-22-2010, 06:43 PM   #7
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Quote:
Originally Posted by nwmtech View Post
+1. Nice write up. I was fortunate and was able to be a bystander at Todd and Matt's flight school this year in Snohomish, WA. I was able to stand behind a buddy of mine taking the class and was quite shocked when Todd told my buddy to auto at midstick (it was a 700). I would never had thought it possible until I saw it with my own two eyes. He never went negative and was able to keep the headspeed up by finding that sweet spot with the angle of attack. Just goes to show that VERY LITTLE negative pitch is needed.
that's nothing try it with a 250, it's like doing auto with a brick.
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Old 11-01-2010, 01:31 PM   #8
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I was doing autos on reflex with a raptor50 last night and managed to actually pull a few with just negative pitch! At loss of power I pushed the nose down about 45-50 degrees, let the heli gain momentum and the blades were spinning up real fast at about minus 8 pitch, then pulled the heli out of the nose dive and without touching the pitch I was able to land (maybe twice... mostly otherwise I think I would get out with minimal canopy damage). I can't really explain, but it works. I'll try to do a vid tonight, problem is I have reflex 5.0.3 and I don't think it can show stick moves.

When I added positive pitch and flaring at the bottom point, I was able to actually hover for about 5-6 seconds above ground from the energy stored in the blades.

By the way Raza, how do you manage autos from vertical nose down? If I cut throttle in that orientation and wait 3-4 seconds before pulling the collective back (assuming that'd be time to realize that I have no juice and react), I can't recover any more from the nose dive.
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Old 11-01-2010, 01:45 PM   #9
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Quote:
Originally Posted by Tomy. View Post
I was doing autos on reflex with a raptor50 last night and managed to actually pull a few with just negative pitch! At loss of power I pushed the nose down about 45-50 degrees, let the heli gain momentum and the blades were spinning up real fast at about minus 8 pitch, then pulled the heli out of the nose dive and without touching the pitch I was able to land (maybe twice... mostly otherwise I think I would get out with minimal canopy damage). I can't really explain, but it works. I'll try to do a vid tonight, problem is I have reflex 5.0.3 and I don't think it can show stick moves.

When I added positive pitch and flaring at the bottom point, I was able to actually hover for about 5-6 seconds above ground from the energy stored in the blades.

By the way Raza, how do you manage autos from vertical nose down? If I cut throttle in that orientation and wait 3-4 seconds before pulling the collective back (assuming that'd be time to realize that I have no juice and react), I can't recover any more from the nose dive.
Nice good job, you pretty much got it. As for nose down, you have to be very careful with that. Doing an auto is about getting air through the disc. When nose down and air is going across the disc like that you'll slow the blades down so much you may well indeed loose all cyclic control and not even be able to level out.

If you nose down at all do it very briefly and high up to give yourself time to level out and spin the blades back up with just a few degrees of negative pitch. Too much negative pitch can actually cause too much load and not spin the blades back up as quick.
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Old 11-01-2010, 02:01 PM   #10
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Thanks Raza. I thought I was missing an obvious trick, but you pretty much re-enforced what I thought, if I ever lose power nose down and can't pull out immediately, I'm hosed . BTW I'm not flying nose down, I was more thinking about being in the middle of vertical tick-tocks, I was never able to pull an auto from there. Thanks anyhow!!!
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Old 11-02-2010, 05:34 AM   #11
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I was able to capture a few vids from Reflex so here are the first few of my full negative pitch autos. Far from spectacular but definitely show Raza's point.

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Old 11-03-2010, 05:30 AM   #12
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Quote:
Originally Posted by senone View Post
please post a auto video

I'm sorry I didn't even see your request. here's my 250 auto video. It's soo much harder to do an auto with a 250. I can do inverted autos on bigger birds. But for the life of me I have trouble with the 250. I know, I know Raza, is going to tell me again, Poor Collective Management. That is why I am here again!!.How's my auto raza? It's harder with the smaller bird!

Senone: anyways your video that you requested.

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Old 11-03-2010, 05:34 AM   #13
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Raza: I can do indefinate tic tocs now. I am so happy. You taught me how to do tic tocs. Thank you. But my overall flying is crap. I don't even know how to do nose in hover!! Where do i start? Give me some pointers for nose in hover please. The same way you gave me pointers for the aileron tic tocs. I don't need the bigger birds, I know I can master these little birds. Everytime I try to practice "nose in hover" I just end up doing freestyle flying. I don't even know what I am doing!! And in real life, it's the same. I just zip around in the air, like in the video, but only 110% faster. When I really do try to do nose in, I keep getting blade strikes. What am I doing wrong? Where's the "nose in hover" thread? I need your help, please Raza.

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Old 11-07-2010, 11:50 AM   #14
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Here is an auto training video I did about 2 years ago.

VIDEO -> Learning to shoot autos on a 450 and showing the sticks (39 Megs)

Bob
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Old 11-07-2010, 01:29 PM   #15
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Nice. Goes to show how little neg is really needed. To those that think you need full down stick you can see Bob barley ever went further than a full tick mark below center.

Awesome thanks Bob
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Old 11-07-2010, 03:15 PM   #16
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Nice Bob, where would we be without those?
So true Raza, with full negative pitch you'll basically fall off the skies until you increase pitch. With just enough negative pitch throughout the entire auto the driving region will continuously provide enough RPM with enough lift for a constant slower decent that allows you position the heli for landing.
There are many good articles that talk about blade regions during autorotation and their roles at different pitch, in rchelimag here http://rchelimag.com/pages/howto.php?howto=13&page=4 or on copters here http://www.copters.com/aero/autorotation.html.
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Old 11-09-2010, 06:00 PM   #17
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Quote:
Originally Posted by RĒzĒ View Post
Nice. Goes to show how little neg is really needed. To those that think you need full down stick you can see Bob barley ever went further than a full tick mark below center.

Awesome thanks Bob
Hi, I'm finding these threads really useful. I've got quite a bit of stick time on RC planes, mainly gliders, including dynamic soaring and I fly real Airbus for a living so I have loads of stick time on big planes too but i'm new to helis. I studied a little bit of helicopter dynamics in ground school many years ago and it's all very useful in understanding what's going on. Regarding your quote above, I gather Bob was in idle-up at the time?

As a newbie, there's no way i'll be going near idle-up any time soon. I have a TRex 450 Sport that i've just moved up to from a Honey Bee cp2 and i'm interested in what sort of blade angle is needed for autos. I have my 'normal' mode set up pretty much as per the manual. I used a pitch guage and I wrote down my setup:

Zero stick = 0 deg
50% stick = 4 deg
100% stick = 9.5 deg (I kept it conservative as a beginner because I didn't want it to be too much for me to handle, i'll increase it when i'm good enough).

I know a couple of real life heli pilots so I could ask them for the full auto-rotation blade theory lecture but in practice, using RC helis, you guys know what's going on. In my early days, I can't help feeling vulnerable - if I have some sort of failure, I really am in the lap of the Gods... but what with volcanos, famines and floods troubling the planet, I don't think my prayers would get much of a look in at that point.

Any feedback and/or techy details appreciated.
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Old 11-15-2010, 07:35 PM   #18
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Hot Air,
I see no one has answered you, so I will throw in my 2cents, even though I am a relative beginner. Everything I have read, everyone I have talked to says that at 0 stick you should have some negative pitch, -2 to -3 degrees. At 0 pitch, you can still have an attitude that yields some positive pitch, therefore allowing the machine to float too much.
Look into some booke/DVDs by Ray Hoestetler, they are very useful.
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Old 11-15-2010, 09:10 PM   #19
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I agree with rharms. -2 or -3 should be about right. Even at those values if you chop the throttle you won't slam the ground too hard. IMO you should practice autos early on. I started by hovering about two feet up and hitting throttle hold (don't touch the collective). Watch the tail swing as it will when the power goes away. This gives you a feel for how the bird settles without power. When you are comfortable with the settling process start to play with the collective to see how long you can stretch the hover. Move up to three feet and four feet. When you get to the point where your alitude will not allow you to land softly you then go up high and do a real auto.

One thing for sure.... you either land or crash... Or is it crash landing

Is this the right way to learn and auto?????? I don't know, but way back when this is what I did. FWIT, My GMP Cobra was very easy to auto. My X-Cell 40 I've NEVER been comfortable with autos.
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Old 11-16-2010, 12:17 AM   #20
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Quote:
Originally Posted by Finless View Post
Here is an auto training video I did about 2 years ago.

VIDEO -> Learning to shoot autos on a 450 and showing the sticks (39 Megs)

Bob

This is a really good video for autos. This is how I learnt how to do autos. Thank you bob for all your videos. I refer to them every so often for a refreshing course and motivation. One thing I learnt with a 250, I have to have a bit more negative, so that I have more HS to have tail control. Any tips for inverted autos on a 250? I can do an inverted auto on bigger birds, just not with a 250. If you know anyone that is able to do an inverted auto on a 250, a video would be awesome to see, specs and AUFW including lipo would be good aswell. That is if I'm not asking too much . hehe
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