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HelicopterMain Discussion › Trouble learning autos
06-18-2014 12:13 AM  3 years agoPost 1
Harry Spillett

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Faversham, Kent, England

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Hi guys,

I am after some help with my autorotation practice. I have tried making a number of descents in Throttle Hold but cant seem to achive a smooth descent because the model keeps wanting to "porpoise" and loose forward speed. I find I have to really push the nose down in quite an unnatural way, almost like a dive.

If I make an approach in Normal or Idle up mode the model can be brought down normally at about a 45 degree angle.

The model is a Raptor 30 V1 (I know, old school these days!) With an OS32 engine, constant driven tail and stock wooden blades.

My pitch curve in Normal and Idle Up 1 is -4 degrees at the bottom, hover (at mid stick) 8 degrees, 12.5 degrees at top stick. This increases to max pitch 14.5 degrees in Throttle Hold.

Any help would be appreciated.

Regards,

Harry

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06-18-2014 12:25 AM  3 years agoPost 2
TMoore

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Cookeville, TN

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With that setup you'll have to come down hot and catch it at the last few moments or have a good headwind and keep the blades spooled up with back cyclic. At any rate give yourself a few more degrees of negative, you don't really need 12.5 degrees of positive to do autos but it won't hurt. A set of good CF or fiberglass blades will certainly help the head speed a little and make sure you are dead straight into the wind when you land. The R30's were lost of fun without the driven tail and with the driven tail they lose just a little inertia at the bottom.

TM

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06-18-2014 12:58 AM  3 years agoPost 3
Harry Spillett

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Faversham, Kent, England

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Thanks,

I used to have more negative pitch on both curves, more like -6 degres but the model seemed to fall out of the sky with that, is this the sort of negative pitch I need to be using?

H

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06-18-2014 01:00 AM  3 years agoPost 4
TMoore

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Cookeville, TN

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I run the same on top and bottom but don't use it all. -6 is fine.

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06-18-2014 01:07 AM  3 years agoPost 5
Stephen Born

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USA

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and stock wooden blades.
Wood blades do not auto with such grace as other blades.

Practice autos 3ft. from the ground. Raise in altitude increments when you reach level of comfort.

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06-18-2014 01:16 AM  3 years agoPost 6
TMoore

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Cookeville, TN

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Wood blades auto fine if they are loaded with lead which the R30 stock blades were if that is what is on the heli.

http://www.ronlund.com/rcheli-prod/.../ACEPV0039.html

They won't have the inertia that CF blades will but wind will take care of that.

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06-18-2014 01:17 AM  3 years agoPost 7
Ladymagic

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South Korea

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I willing to bet your CG is too far aft. It could be a misadjusted trim, paddle, un level swash. That's why you have a hard time keeping the nose down. You might want to check that and see if their is anything you can shift forward to change your CG.

As TMoore says,

I think the main issue is those wooden blades. They bleed off head speed much faster than a good set of CF blades will. That coupled with the fact that .30 class machines aren't the best auto machines anyways. But, when you you learn to auto a .30 class, you'll can pretty much auto anything.

You should immediately drop your pitch to around -2 degrees once you hit TH. Keep your inputs slight and deliberate and follow a glide path and a landing zone that you set in your head. Seems like all those extra inputs trying to keep that nose down is eating away your HS faster. And I find it easier to auto .30s when you enter the autos with some airspeed...there's just not a lot of rotating mass to work with for dead stop autos on those .30s.

I like to use a half-horse shoe pattern for non-stunt autos on smaller helis. That will gives you a cushion to help keep your HS and AS up and a bail-out option at the same time.

Good luck! And safe flying.

Mellisa

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06-18-2014 01:56 AM  3 years agoPost 8
rcflyerheli

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Granbury, TX USA

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I don't think 14.5 degrees pitch in TH is necessary (or good on this sized heli). You aren't trying to do anything but break the descent, and if you apply that much collective, it will sure stop light blades.

Goblin 700, Trex 700DFC, Gaui X7, Logo 690SX, Logo 600SX; Trex 470 Trex 500
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06-19-2014 04:39 AM  3 years agoPost 9
jschenck

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La Vista, NE.

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I learned to auto with a Raptor 50 V1 and wood blades, it auto's just fine, so do the wood blades. Here are a few hints.

1. Make sure you have the same amount of trim adjusted in throttle hold mode as you do in your other flight modes. It sounds like your trim is off.

2. Stock Raptor head is limited to about +/- 11 deg collective, make sure you have 11 deg positive and negative with your pitch curve setup straight, then adjust your radio pitch curve to the way you like it.

3. For throttle hold mode ensure you get a minimum of -6 deg and +11 deg pitch, I'd look for more neg but you'll be able to shoot them with -6.

4. Make sure your paddles are properly lined up, if they are out of alignment it'll cause issues.

5. Start off with baby auto's like mentioned above - standing hover 3' off the ground hit throttle hold and just land it. Do this until it's 2nd nature.

6. The first few times you shoot an auto choose a day with a slight breeze, say 5-8mph. It's way easier than a day that is dead calm.

7. shoot the auto straight into the wind. Fly a circuit at as high as you are comfortable at a normal to slow-ish speed then hit throttle hold once you are just about over your shoulders. Shoot for a straight ahead landing. The #1 goal at this point is to keep the rotor disk as flat as possible while maintaining forward speed. Listen for the blades to make a nice brrrrr sound. Adjust collective to get that sound, not too much negative.

8. When the heli gets about 6' off the ground pull back on the elevator but keeping negative collective - to stop the forward momentum.

9. Once the heli has zero ground speed, level it, should be about 3' high now, just land!

Read this, a few times and really try to understand what he's saying

http://www.ronlund.com/autos.htm

Better blades *might* make it a ittle bit easier but technique and wind makes a bigger difference.

I liked learning with wood blades just because if you do make a mistake and bust a set of blades it doesn't cost much to replace them.

fyi - My Raptor I learned to shoot auto's with did not have a driven tail (red tail drive gear). No control of the tail in auto's but that didn't matter with a solid tail fin and shooting straight into the wind. It did make the auto easier since no energy was being spent driving the tail blades.

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06-19-2014 05:04 AM  3 years agoPost 10
revmix

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NJ

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hover (at mid stick) 8 degrees
mid-stick at 50% should be 0 degree, hover is 4.5-5 degrees about 65-70% pitch curve [depends on headspeed]
with 8degrees hover the heli has too low headspeed, with 8* pitch heli should be up in mid-air
-4 degrees at the bottom
for autorotation -4* is about -35% just below mid-stick
"porpoise"
not enough inertia [due to low disk RPM]

TT heavy wooden blades are excellent for autos

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06-19-2014 08:19 AM  3 years agoPost 11
Funky Trex

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Westerville, OH - USA

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That much pitch usually drains too much headspeed in a heli without much inertia. It was many years ago and I wasn't any good but I used to do a lot of autos on my old R30. I ran wood blades too and it worked ok, but I only ran around 10 degrees of pitch. The motor was worn out and wouldn't handle much more. It still had plenty of pitch for standard autos though.

Watch at YouTube

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06-19-2014 11:06 AM  3 years agoPost 12
Ace Dude

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USA

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-4 on the bottom is fine. I'd limit the top to 10 or maybe 12 degrees max.

This is how I learned how to auto on my 30 sized shuttle ZXX with woodies and no driven tail back in the mid-90's.

  

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06-19-2014 12:19 PM  3 years agoPost 13
jackp332

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Claremont, Nh USA

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+ 1 Ace Dude. I have about -4 on my throttle hold. As a new learner to autos it's all you need. Can you have more? Sure. But as a newbie, modulating the collective on the bottom will be one more task to think about. If you have much more than -4 on the bottom you will find yourself falling like a rocket ship. It's more than enough to maintain rotorspeed on descent. Read the detailed explanation by RonLund. It was invaluable to my learning autos.

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06-19-2014 02:11 PM  3 years agoPost 14
Four Stroker

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Atlanta

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+2 Ace Dude. Don't let these macho guys crash YOUR helicopter. If you hover in normal mode at mid stick, then HOLD should have the same pitch at mid stick. HOLD and normal should be about the same with maybe limiting negative pitch in HOLD. A smooth pitch curve is good. Going past a sharp kink can cause the heli to jump.

Some beginners do just fine on pitch with -12, 0, +12. Some just can't find the right pitch to come down. Remember that you are flying all of the heli all of the way down.

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06-19-2014 02:52 PM  3 years agoPost 15
revmix

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NJ

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pitch with -12, 0, +12
with this setup
hover in normal mode at mid stick
center is flat pitch

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06-19-2014 02:54 PM  3 years agoPost 16
Pistol Pete

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Seffner, FL

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Listen for that "brrrrr" sound mentioned by jschenk in the video from funkytrex at the 3:20 mark...best auto IMHO...spot on.

Heavier paddles also helps.

~~Enjoying the hobby one flight at a time~~

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06-19-2014 06:10 PM  3 years agoPost 17
Tyler

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Chicagoland area

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Does your heli fly well hands off with all the trim tabs at center position in every flight mode, aileron, elevator, rudder in normal, idle1, idle2?

Does your TH mode match those same trim settings?

TH mode may need slight trimming because there is no engine torque.

Fly to altitude straight and level, hit TH and watch the helicopter. It should maintain its course. This only requires about 2 seconds of flight to observe. Switch back out of TH. Land and make needed adjustments.

Your goal is to have a model that does not change at all when you hit TH.

TH and normal flight modes should be identical pitch curves. I suggest more than -4. Use what you need. This is called being a pilot. Sometimes you may find yourself in a situation that requires more than -4 to spool up those blades again. It is a sick feeling to watch a model fall out of the sky because you cannot spool up the head again after a miscalculation or failure.

12.5 degrees of pitch on a Raptor is too much. -10/+10 is perfect. You should never rely on bonus pitch at the bottom of the auto to bail you out. Maintaining the proper head speed and collective management is the proper way to fly an auto. Those big jabs of pitch at the bottom are a crutch that will bite you more times than not because they can suddenly launch your helicopter from just above the ground to the deadly 4-6 foot altitude while consuming the last bit of blade inertia you have. There will be nothing left to land softly again. I watch guys do this all the time, and they bust up more parts with this misconception than if they would just accept the cost of learning to do autos properly. So what if you crunch a few times, just consider it tuition fees. After you graduate, the diploma of auto rotations 101 will repay your many fold.

Keep your head speed up when you enter TH.

I agree with checking your balance and paddle alignment, which all goes along with trimming the flight modes properly.

I learned autos with Raptors and wood blades, so have many others, and so can you.

Enjoy things that money can buy IF you don't lose the things money can't buy.

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06-19-2014 10:55 PM  3 years agoPost 18
Harry Spillett

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Faversham, Kent, England

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Thanks for your advice guys,

I have tried the baby autos and these went ok, It is since I have progressed to the attempts with forward flight I have had problems.

After reading all of the posts I think I will leave my bottom stick pitch at -4 but reduce the maximum pitch in both Normal and Throttle Hold flight modes to +10 degrees. (I had set +12.5 degrees originally as this allowed a full power climb out without the engine bogging down, I expect it will over speed a bit with +10) Both flight modes will then be identical in every way except that the throttle servo is inhibited in Throttle Hold.

I am happy that the model is well balanced. I added a larger fuel tank a while ago which moved the C of G aft, however I counteracted this by adding a larger RX battery to bring the balance back. As the tank empties the balance should move forward slightly.

I set the model up with a slight offset on the swash plate to help reduce the translating tendency in the hover and it is very stable on a calm day with no wind.

I will investigate the action of the trim in Normal vs Throttle Hold. (I use a Futaba FF9 TX). Because the model is so stable I rarely use any trim in any flight mode. The only think I do use is throttle trim to help with the first start of the day and then to reduce the idle for the remaining flights so the clutch does not drag.

I need to check and possibly increase my head speed, i am not sure what it is at present. As one of you mentioned my hover at +8 degrees and 50% throttle does not seem right.

I have heeded everyone's advice of practicing with a slight head wind but perhaps it is too much for the model and slows it down too much.

Thanks for the video clip, i had seen that before and it looks frustratingly easy! I have heard the "Brrrr" sound from my blades briefly but then the nose comes up and i have to push it down again. Obviously i dont have long to "fiddle" with the approach before i have to flip the switch and bail out.

Hopefully will have another go on Sunday!

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06-19-2014 11:02 PM  3 years agoPost 19
Ace Dude

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USA

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The number one most important goal should be to find a qualified instructor to help. You'll be amazed how easy it will be learn new maneuvers (including autos) when working with someone who can not only fly well, but can also teach.

  

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06-19-2014 11:21 PM  3 years agoPost 20
Copter Doctor

rrProfessor

Enterprise/ft.rucker ,al- home of army aviation

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The number one most important goal should be to find a qualified instructor to help. You'll be amazed how easy it will be learn new maneuvers (including autos) when working with someone who can no only fly well, but can also teach
hands down, the best advice here. many folks can fly, but not really teach so select an instructor carefully. Unfortunately when i learned to fly jhelis back in the 80's, i was the only fool willing to fool with helis so i was on my own
i learned autos by cheating. i kept the throttle hold a little higher than an aidle to help me with the descent, flare and cusioning. i used wood blades back then because thats all there was for my hirobo shuttle (original blue canopy) today its worth getting a good set of glass or cf blades, they do better because they are heavier and have a more efficient airfoil with less drag. if you are learning autos then i am assuming you have a sport flier setup on your heli and not a 3d setup. sport flying for a raptor would mean about -4 to -6 degrees at low stick, +4 to +6 at the hover and +10 to +12 at full stick. this is in the throttle hold mode of course. for regular flying, i would only decrease whats on top to +7 to +9 at full stick.
anyway, if -6 makes it drop out of the sky too fast, no worries, just come up on the stick a bit to slow the rate of descent. the heli drops quicker at -6 than it does at -3 better to have too much negative at the bottom than too little because you can adjust this while in flight.
with a good setup, you can now use the engine to help you. a little higher of an idle with the throttle hold on will help simulate heavier blades and give you a chance to recover from a bad entry or decent. as you get used to adjusting your rate and angle of descent, the flare and cusioning during the auto, you can lower the idle a little at a time til its not helping you anymore and the blades are doing all the work. i learned autos this way and ive taught many many folks to fly rc helis and this seems to work the best and fastest with no accidents. ( i do use a buddy cord by the way). hope this helps and good luck.

drive a rotary, fly a rotorcraft

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HelicopterMain Discussion › Trouble learning autos
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