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HelicopterBeginners Corner › Some Setup Questions
09-03-2003 09:44 AM  14 years agoPost 1
nheather

rrKey Veteran

Horsham, West Sussex, UK

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I am currently learning to hover a Hawk Sport which I have built to the manual. It hovers okay but I'm considering revisiting the setup in light of comments made by experienced flyers at the club field and on this forum.

In particular, I want to lower the swash as it is sitting too high at the moment, get all the cranks level/or at 90deg, change my hover postion from 1/2 to 3/4 stick and generally remove a bit of binding.

I have Rays manaul and am quite comfortable following his instructions and then getting a final check over but before I embark on this, I'd like to check whether Ray's manaul is still relevant. I'm concious that it was written some time ago and helis and ideas may have moved on since.
Two points in particular:

Pitch - use a short servo arm with loads of ATV
Throttle - use a long servo arm with little ATV - (to the extent of using a short arm on the carb)

Is this still recommended practice, as it differs somewhat from the Hawk manual?

Cheers,

Nigel

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09-03-2003 10:49 AM  14 years agoPost 2
nheather

rrKey Veteran

Horsham, West Sussex, UK

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Janek,

Thanks for the prompt response. I really am just tail-in hovering at the moment - going slowly because loads of other demands on my time.

Advice I have been getting is to start of on 3/4 stick as earlier as possible so it's not such a mind set change later on. So I'm happy to give to a go now.

Cheers,

Nigel

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09-03-2003 05:55 PM  14 years agoPost 3
wolfdad

rrKey Veteran

Southern Maryland

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75% Hovering

Nigel,
I am still a rank beginner, so all I can do is tell you what has worked for me so far.

First, of all, in ALL capital letters, YES, Ray's manual is still very much relevant and, in following his suggestions and recommendations, I have had nothing but success. I even take his manual with me to the field when I go flying, for reference.

I set my Voyager 50 up for 75% hovering and that's how I am learning to fly. I like the 50/50 philsophy (50% pitch above and 50% pitch below the mid stick point), although, at this point in my "learning curve," I still have not started putting any negative pitch in. The Voyager is set up with a +9 degrees/-9 degrees total collective travel, however I am currently set up with about a +8 degree/0 degree pitch curve. This gives me enough positive pitch to counter the weight of the training gear, yet I won't slam the aircraft into the ground with negative pitch (I have a tendency to plant the aircraft back on the ground when I start getting antsy). That's what has worked for me so far.

A couple of beginner's comments on some other things in your post, if you will. You mention the fact that you think your swash plate is too high. What/who makes you think that? First thing I would recommend is go back through your rigging and, after building all your control rods, arms, etc., in accordance with the instructions (most manufacturers will tell you that their recommended control rod lengths are a recommended starting point only), then starting with everything at 90 degrees (servo/control arms, etc.), level your aircraft (this is a key step), then your flybar and lock in place, and finally, level your swash plate with your collective at the mid position. Once you have done that, check your blade angle at mid stick. Should be right on at 0 degrees. If not, adjust your pitch links accordingly. Check both blades, ensuring they are both at 0 degrees as a part of this step. Once you have done this, you can set your pitch range accordingly, using the swash function on your radio. If any of the steps above are not "dead on," the rest will not work. Again, this is what has worked for me in setting my Voyager up.

You also mention eliminating some binding. Do this immediately and prior to attempting any rigging. If you have any binding, no matter how small, find out now, what is causing it and correct it. Don't blow it off and figure that it will "work itself out," because it most certainly will. It will work itself out with a huge dive into your wallet to repair your busted bird.

Those are the things that work for me. Email me if you have any other questions.

wolfdad sends

"There are those who have...and, those who will" IRCHA #2117, AMA #70068, Turbine Waiver #105

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09-11-2003 04:52 AM  14 years agoPost 4
jbutkovic

rrApprentice

Cumberland, ME

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Try this....................

pitch (stick position all modes):

low - (-10)
1/4 - (-6)
1/2 - (0)
3/4 - (+6)
full - (+10)

Throtttle (normal mode)

low - (0%)
1/4 - (25%)
1/2 - (50%)
3/4 - (75%)
full - (100%)

Throttle (idle up)

low - (100%)
1/4 - (75%)
1/2 - (50%)
3/4 - (75%)
full - (100%)


At half stick (stick in the middle), all links should be at 90 degrees, pitch should be 0, and throttle should be at 50% no matter what mode you are in. Hope this helps.

Joe
jbutkovic@maine.rr.com

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09-11-2003 08:34 AM  14 years agoPost 5
nheather

rrKey Veteran

Horsham, West Sussex, UK

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Garland,

I've got mine setup and very nicely now. Reading the books was quite confusing but now it all makes sense - as you say the books do tend to skip over little bits.

Right, onto your questions:

1/2 stick, 3/4 stick etc refers to the physical position of the transmitter stick and NOT the servo position.

Without touching pitch or throttle curves yet

Geometry first. At half stick you should have:

Pitch = 0 deg
All cranks, arms, link/servo etc level or 90%
If you've followed Ray's instructions the pitch servo position will be 50%

At full stick you should be at you positive pitch limit (say +10%)

At zero stick you should be at your negative pitch limit (say -10%)

Now you go to your curves.

Pitch is easiest. You want to set the bottom to be your required maximum negative and the top be be your required maximum positive.
1/2 should be set to 0 degs which if you have followed the instructions, it already is.
3/4 stick should be set to your hover pitch. Incidently, you say yours is 8 degs - this seems rather high - I'd expect around 5 degs
1/4 stick set the pitch between your minimum and zero.

I'm only beginning so I set my pitch curve up as

-1, -1, 0, 5, 9

Now throttle needs to be set up to achieve the correct headspeed throughout the pitch range. I don't have any fancy tools for doing this. The important ones are 50% at 3/4 stick (hover) and 100% at top.

I set mine as

0, 15, 25, 50, 100

If I had the appropriate tools I'm sure this could be made better but it appears to work well for the time being.

So in summary, the two key points are:

0 degs pitch at 1/2 stick - this is where you set up the geometry
hover at 3/4 stick - typically 5 degs pitch / 50% throttle

Cheers,

Nigel

STOP PRESS: I've just read the reply from Joe and it seems that whilst my pitch setup concurs (although beware, if you are beginning, he has recommended too much negative pitch - only want -1 or -2), we disagree on throttle. I'm not sure which right but as I am a beginner I'm always happy to be corrected. From my personal setup though, 50% throttle at 5 degrees of pitch gives a pretty high headspeed - I feel that if throttle were any higher, it would scream the nuts off the head.

Cheers,

Nigel

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09-11-2003 11:59 AM  14 years agoPost 6
pistole

rrVeteran

Heli Land ....

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I will say this though.

The numbers for your pitch and throttle curve do not matter. They are just values assigned by the TX. What is important is just to setup basic curves values (which are readily available in any heli manual) and then to fine tune it on the field.

The fine tuning ought to be performed by an experienced pilot , who will be listening for headspeed and cyclic-sensitivity in order to determine a stable headspeed for hover which is just fast enough to hold the heli up in a stable hover but not any faster than that because then the cyclics become incrementally more sensitive to input.

There is really , no need to keep bandying about those pitch/throttle curve numbers as though you were quoting from scripture.

As for the 1/2 and 3/4 stick hover thingy. My take is that it also does not matter for a beginner learning to hover what stick position you're on for your hovering. My answer to the query is a simple , who cares , since it does not matter.

What does matter is when you want to transition to Idle Up. Even then , your initial idle up setup can be tuned to be mild and not the complete +9/-9 plus V-Curve Throttle. Thus said , if you've reached a level where you feel comfortable to switch to Idle Up , where your coll. stick is , is really irrelevant as you'll learn to anticipate the heli's behavior upon switching and you can adjust for it.

Conclusion
_____________

So , go slow on the numbers.

No need to be anal about the settings.

Just have a basic setup programmed into your Tx (assuming , of course , that your heli mech. setup is ok) and then have someone experienced tweak it for stable hover.

And then , start burning fuel.

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09-12-2003 01:44 PM  14 years agoPost 7
choppertime

rrApprentice

Virginia Beach, VA

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I think the numbers (t-curve p-curve) in the book become much closer when the mechanics are as Ray has said in his book. If your numbers are different like jbutkovic's then I would suspect a mechnical difference from what Ray preaches. But there are a lot of variables that could make it change a little.

Personally I don't use subtrim and set everything exactly semetrical with the center of the mechanics corisponding to the center of servo travel. Sometimes you get servos that don't match. Just something to look for.

_____________________
See ya at the flying field...

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09-12-2003 07:35 PM  14 years agoPost 8
Richard

rrVeteran

Scottish Borders, U.K.

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Nigel,

Don't be afraid to change to 3/4 stick. When I was a complete beginner, I read Rays book and changed. It is not that hard, after one tank, I never noticed the difference. It makes changing from normal flight mode to idle up less scary.

Richard

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09-12-2003 08:08 PM  14 years agoPost 9
Drunk Monk

rrProfessor

Preston, UK

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I learnt with hover set to 1/2 and could fly circuits, figures 8's stall turns, changing to 3/4 only took a few flights to get the hang of so personally I wouldn't worry too much about it yet.


Stephen

I only open my mouth to change feet.....

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