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HomeAircraftHelicopterMain Discussion › autorotation pitch
02-16-2003 04:19 AM  15 years agoPost 1
pabloss

rrNovice

Capri island - Italy

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Hi, with my Freya I do every day some autorotation, but after the flare the rotor power to land is too low. Maybe I must go down faster, with more pitch to have more power??
How can I do a perfect autorotation landing with all power I need??
Thanks to all

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02-16-2003 04:27 AM  15 years agoPost 2
Heli-Driver

rrElite Veteran

Arlington, TX

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If your auto bearing is spinning well and has minimal drag then it's likely you just aren't managing the collective properly during decent.

Ron Lund and Mike Mas has some great autorotation information available. I run about 12-13 degrees pitch on hold. With a decent entry I can usually hover a few seconds before touching down.



Raymond

Predator Gasser SE/231 X 2
Century Helicopters

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02-16-2003 05:00 AM  15 years agoPost 3
Phil Cole

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Menlo Park CA

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The head speed while in the main part of the descent should be about the same as you have while flying with engine power.

If your head speed is too low in the descent, then there are two main reasons:

1. Descending too slowly. Fix this by descending faster. You should see or hear the rotor speed up within a second or two. If you don't see the speedup, then you are probably descending at the right speed.

2. Incorrect attitude. The rotor should be almost level with the ground. If you descend as if you are diving like an aeroplane then the air can't flow through the rotor properly. The nose-down attitude you have in fast forward flight is too much for a good auto - you do need to pull the nose up a bit as you start the auto, but not too much, otherwise you will lose all your forward speed. It is OK to dive slightly to pick up forward speed, but you must level out afterward.

You should be in forward flight at a medium speed just before you start the auto. Just before switching to hold, bring the collective to negative and level out. This way the heli is already in auto mode before you cut the engine, so there no chance to loose head speed while establishing the conditions for autorotation.

The other thing is not to flare too early, or too hard. If the heli has the right attitude, you won't be going all that fast. I start to flare at around 5 m (15 ft), but very gently. As the flare starts, I will decrease collective even more, to stop the heli climbing, and to put the heli's kinetic energy into the rotor. The descent rate should stay the same, but you will be losing forward speed. Aim to arrive at the landing spot at a height of 1 m, with zero forward speed. You should have lots of energy in the rotor.

Now try to land as quickly as possible. If you try to hover at 1 m too long, you will lose all your rotor energy, and bounce onto the ground.

If you are getting too low and still have too much forward speed, just slide along the ground, using the collective to keep most of the weight off the skids. The friction will slow the heli down nicely. Sometimes I just slide for the fun of it. With practice, 100 m slides are possible. Of course, sliding is not a good idea on bumpy ground, but it's better then hitting the ground and tipping forward, breaking your blades.

It may help to get someone to watch what's happening, since you have to concentrate on flying. Ask them to watch the rotor speed as you fly through the parts of the auto, and also when you change your descent speed and attitude.

A good way to practice the approach, flare, land sequence is to do it in normal mode. Just to do the whole thing in one single, flowing motion without wasting any time along the way.

The secret to perfect autos is to do lots of them and learn from your mistakes, both big and small.

Man, that's a lot of stuff I wrote . It's hard to know what your problem is unless I see what you're doing, so I had to cover all the possibilites.

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02-16-2003 05:42 AM  15 years agoPost 4
MR SLOWFLOW

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N.J/N.Y

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there's nothing left to say Coles covered it

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02-16-2003 12:23 PM  15 years agoPost 5
SAL

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Oakville, Ontario, Canada

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Phil Cole quote:
-----------------------------------------------------------------
With practice, 100 m slides are possible
-----------------------------------------------------------------

Are you sure???

SAL


.

[color=red]SAL[/color]

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02-16-2003 07:22 PM  15 years agoPost 6
Phil Cole

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Menlo Park CA

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Sal,

I can't do a 100 m slide, but I've seen it done. Expect to wear out a few sets of landing gear practising.

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02-16-2003 11:56 PM  15 years agoPost 7
donlynn

rrKey Veteran

New Zealand

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Rtt36 std,200 tanksSAB cf sym mains hold ~ -5 +12
Gidday

COOOOOOL 100m auto ground roll !!!!!!

Is this damp bowling green downwind,or is that after? ice maybe?

I'd donate a straightened r30 skid to see that, I have a glut of the skid to leg ratio!!
I'm visualising the wake / rooster tail !!!!!!
I'll add my experience as I'm just at the moment learning autos so you can have a newbis experience, Sorry for the ramble I'm not a journo!

I've been doing Autos all weekend after Si (littlerotors .com) coached me thru my first intended ones last weekend in Nelson, -awesome, thanks Si
.
This weekend 4 hrs sat, 6 hrs sun, getting tidier, what a huge difference what a rush, first time I've really had fun while I'm flying rather than when landed, purely cos of the confidence boost with a little ability to recover from engine failure, provided it's at 200 ft pointed into 10-15 kt wind!!.

As I'm a newbie I am slowly working out what Phil has said to be on the money, although I too look foward to the 100m greaser vid !

Decent speed , Si had me change to -5 from -~2.5 previous, what a difference,
I was able to cock up collective application rushing to arrest the decent at the bottom several times at the bottom(once back up to 5 ft from 2 ft) and provided I checked cyclic forward just b4 touchdown to get the boom away from the ground.
I was lucky enough to have my last auto boom strike videoed and sure enough frame by frame it looked exactly as if you took a boom with tail attached and struck it into the ground it bounded back exactly as you would think.
A new skill to refine -no worries it would try hard as to fall foward, sideways off the skids ,bounce a foot into the air try to fall over again, toward the end of sunday I was getting the occaisional one to about 10-15 degrees boom up which felt cosy, also the breeze was a nice 12kts.
I was busy trying very hard to nail the approach angle 45 degrees or more -plummet with NO noticeable build up in head speed,and large genital shrinking component, 20 degres a little better on both counts , this is where I used to practise using Nate's natescape normal curve system as I've been watching the local 3D flyer doing them with the hell flare at the bottom, good for him, he can fly a heli,
I'm not at the speed yet!! around 5 degrees nose down using Nate's plan seemed to be on the money, good head speed , wee bit of airspeed my guess ~15-20 kts so a bit of vert fin aurthority I suppose as I found it quite easy to go backwards during the decent trying to get the 5 degrees and maintain it. Less than 5 seemed a little higher head speed but to difficult for me to currently manage.

Big thing with gentle nose down attitude I found was I no longer had the hell flare to mange !!

Another thing Si said was to hold heli off the ground as long as possible while learning so at touchdown the head is as slow as possible to minimise any carnage , this bit of advise alone saved me any more damage than a dented boom and tail control guides in the above boom strike, links,blades, flybar straigtened out tracking sweet as.

I kinda sneaked up on my auto's each session doing quick stops at 5 feet to get in the groove managing attitude then altitude while at extreme attitudes, then leaving a little throttle in for the first few to give a little tail control to start with then back it off to tail stopped.

To me effective collective management with finese seems to be something to look foward to, my first plank teacher showed me a sign of a good pilot is one who shows elevator finese , it seems the same rings true of the collective aswell for helis.

I've also found unless it's doing ~10 kts and a new glow plug I should flag it unless I'm feeling lucky.

There is heaps yet for me to work on but I'll give you a breather ,

Giving your bit of golden advise about this stuff would be great for us newbies.

collective pitch management during different phases of the decent.
accurate attitude control as above.
tricks to picking the entry window with differing days, wind, hot high and humid.
tricks to minimise the skitter at and just before touchdown ,although I've found the wee check foward helps with this

Better go do some work
Regards Don

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02-17-2003 10:54 AM  15 years agoPost 8
SAL

rrVeteran

Oakville, Ontario, Canada

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I still think he's having us on, come on a 100m rolling auto, thats a longggggg way to slide.........

Revert to my previous question, are you sure ????

SAL.


.

[color=red]SAL[/color]

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02-17-2003 01:12 PM  15 years agoPost 9
Doug

rrElite Veteran

Port Saint Luice Florida....

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Tha answer is "ice"

First member of Member of Bearings Anonymous

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02-17-2003 08:38 PM  15 years agoPost 10
Phil Cole

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Menlo Park CA

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It was about half the length of a 600 ft ashphalt runway. So, maybe it was 100 yds, and I did a rough conversion to metric since pabloss lives in a metric country.

So, it might have fallen short of the claimed 100 m a bit. Satisfied?

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