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09-15-2007 11:42 PM  10 years agoPost 1
darko

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Bosnia

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Please tell me in normal mode how many degrees of pitch curves should I have in 0 , 1/3 stick , mid stick , 2/3 and full up.
I read it should be 0 at midstick , but I do not know the other ones ?
This is my first gasser so ... ?

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09-16-2007 12:33 AM  10 years agoPost 2
lperagallo

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Westfield, Indiana,​USA

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Most people fly -4, 0, +10 in Normal mode and -10,0,+10 in Idle up.

If you keep a linear curve you have 0 at mid stick, +5 at 3/4 stick and +10 at full stick. In normal just bring it down to -4 at low stick.

In idle up make the bottom stick at -10, 1/4 stick at -5.

Then you can tweak your curve to make it softer around hover in Normal by making the curve a bit of an "S".

If you are not planning on doing any 3D and fly FAI you can hover at mid stick with a different pitch curve matching how you want to fly.

You can follow the crowd or adapt your curve to your flying style. Of course if you are new, you probably want to follow the crowd.

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-16-2007 03:39 AM  10 years agoPost 3
Ts8103

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Baltimore, Maryland

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I ran mine linear with a +/- 12 degrees of pitch. This will basically give you zero at mid stick. This is a 3d setup however. I also ran a head speed rangine from 1850-1920.
Tone

Team Outrage
YS engines
Switchglo
Baltimore Boyz

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09-16-2007 03:29 PM  10 years agoPost 4
AceBird

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Utica, NY USA

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Please tell me in normal mode how many degrees of pitch curves should I have in 0 , 1/3 stick , mid stick , 2/3 and full up.

I think you mean 0, 1/4, mid stick, 3/4, and full, but anyhow the pic will give you anything you want. You should realize that hover pitch is dependant on weight, air density and headspeed. Mine hovers at or around midstick, 3 to 3.5 degrees of pitch @ 1600RPM. This is a graph that I made for someone else looking for a soft hover and if graphs are not your thing then the numbers read across as:

-6,-3,+3,+7,+10

Most people would not 3D in Normal Mode.

Ace
What could be more fun?

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09-16-2007 10:01 PM  10 years agoPost 5
lperagallo

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Westfield, Indiana,​USA

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Ace,

You picture is good if you want to hover near or just above mid stick. While there is nothing wrong with that, If you are going to get into 3D or even sport flying with some areobatics, it's better to have 0 degress at mid stick. If you start with hovering at mid stick, you have to re-learn hovering when you change to 0 degrees at mid stick.

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-17-2007 02:11 PM  10 years agoPost 6
AceBird

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Utica, NY USA

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If you are going to get into 3D or even sport flying with some areobatics, it's better to have 0 degress at mid stick. If you start with hovering at mid stick, you have to re-learn hovering when you change to 0 degrees at mid stick.

All right so you want the standard 3D graph but that is not what he asked for and he didn't state his intentions. Not everyone goes to 3D so not everyone has the need. I find it odd that someone that has the ability to do 3D would have any problem switching to a mid stick hover point to land and take off.

The problem with the 3/4 stick hover point is that it almost forces you to use a governor to maintain headspeed and prevent porpoising.

Ace
What could be more fun?

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09-17-2007 02:54 PM  10 years agoPost 7
lperagallo

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Westfield, Indiana,​USA

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Ace,

I have three machines and use the 3/4 stick hover without govenors and have no issues hovering. Also I'm not sure that you would consider 0 degrees at mid stick a 3D curve.

IMO 0 degrees at mid stick is something everyone will need if you ever plan on using negative pitch in manuvers.

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-17-2007 04:23 PM  10 years agoPost 8
AceBird

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Utica, NY USA

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Pleas explain how you cannot get 0 degrees at midstick if your pitch curve is symmetrical.

Ace
What could be more fun?

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09-17-2007 11:28 PM  10 years agoPost 9
lperagallo

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Westfield, Indiana,​USA

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Ace,

If your last post was directed at my previous post, I don't understand the question. My comment was about your post
The problem with the 3/4 stick hover point is that it almost forces you to use a governor to maintain headspeed and prevent porpoising.
You are correct that 0 degrees will be midstick if your curve is symetrical. Your first chart however, was not symetrical.

Lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-18-2007 09:37 PM  10 years agoPost 10
AceBird

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Utica, NY USA

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Also I'm not sure that you would consider 0 degrees at mid stick a 3D curve.
If you do not do 3D you do NOT need your midstick at 0 degrees even though you may have some negative pitches programmed in your curves.

As I stated before the first chart was made to help someone else. It confirms that not everyone has their midstick position at 0 degrees. Yes, I did make an assumption that the post starter was new. Sometimes it is easier for people to start off with the hover point at midstick instead of ¾ stick because it decreases the sensitivity of hovering. Most people learn to walk before they learn to run.

A butterfly valve like what is the controlling air flow device in your carburetor is not a linear device where as in most radios the 5 programming points are linear. That makes it impossible to maintain headspeed if your hover point is at ¾ stick. And the problem gets worse if you vary your headspeeds. I know a lot of people claim that they hover at ¾ stick but I think they are closer to 5/8 stick and that is a world of difference because you can have a constant slope through the hover point if it is near the 5/8 stick position.

Ace
What could be more fun?

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09-19-2007 02:25 AM  10 years agoPost 11
lperagallo

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Westfield, Indiana,​USA

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A butterfly valve like what is the controlling air flow device in your carburetor is not a linear device where as in most radios the 5 programming points are linear. That makes it impossible to maintain headspeed if your hover point is at ¾ stick
Ace you are correct that on a Gasser the throttle is not linear, however, you can control it with curves. I run my normal pitch curve with 0 degrees at mid stick and a throttle curve to match the head speed I want. I have a DX7 radio and can adjust the curves so they are not linear and with a gasser the curve is relatively flat when compared to Nitro, so I respectfully disagree with comment about not being able to control the hover/headspeed when doing it at 3/4 stick. It just takes patience to get the pitch and throttle curve to work together. When I get a chance I'll shoot a video to show you it is possible.
Lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-19-2007 05:47 PM  10 years agoPost 12
AceBird

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Utica, NY USA

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If you keep a linear curve you have 0 at mid stick, +5 at 3/4 stick and +10 at full stick.
---
I have three machines and use the 3/4 stick hover without govenors and have no issues hovering.
---
so I respectfully disagree with comment about not being able to control the hover/headspeed when doing it at 3/4 stick.
Are you saying you do 3D and your heli hovers at 5 degrees of pitch? Most people doing 3D would be between 1850-2000 headspeed which would put you in orbit with 5 degrees of pitch. It produces 23.3 pounds of thrust at the rotors so do you have your heli weighted down with bricks? And if so, how much 3D’ing are you doing?
with a gasser the curve is relatively flat when compared to Nitro,
Your throttle curve is flat??? That poor engine… and you want me to believe your headspeed is constant???
I have a DX7 radio and can adjust the curves so they are not linear
I just read the DX7 manual and quite to my surprise they have an expo function that will smooth out the sudden changes in slope on the pitch and throttle curves. I wonder how many radios have that feature. More importantly, does Darko’s radio have that feature? At any rate, there is no way he can run 3D headspeeds and expect to hover at 5 degrees of pitch. I suspect it will be closer to three; 3.3 would yield 13 lbs of thrust @ 1850 RPM (sea level).
I ran mine linear with a +/- 12 degrees of pitch. This will basically give you zero at mid stick. This is a 3d setup however. I also ran a head speed rangine from 1850-1920.
Tone
This person right hear is bang on hoverering at 5/8 stick.

Ace
What could be more fun?

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09-19-2007 07:52 PM  10 years agoPost 13
darko

rrApprentice

Bosnia

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Thank you guys for your help !
My radio is RD 8000 and I think it only has linear 5 point curves .
I do not fly 3D as I stated to fly this year , so I basically fly just some basic manouvres . My heli is setup for 3 D but it is going to wait with my current skills.
I decided to buy a gasser as nitro is too expensive , especially for us here as our sallaries are 8 times lower than yours in USA and the price of nitro higher !
I might have some problems with tuning of engine as I do not know when is too lean and when too rich. Basically I tuned the engine and it works well but I have some doubts about those minor corrections to get it perfect.
Is the low speed needle regulating just until the half stick or less and where does the high needle start ? That is a bit confusing for me ! And one more question : when my carb is fully closed I still have nice idle , is that normal or ?

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09-19-2007 10:54 PM  10 years agoPost 14
AceBird

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Utica, NY USA

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when my carb is fully closed I still have nice idle , is that normal
no it should quit. maybe you have a leak somewhere. warn throttle shaft? Is it used?

Ace
What could be more fun?

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09-19-2007 11:54 PM  10 years agoPost 15
Coolrunnin

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Manchester U.K.

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when my carb is fully closed I still have nice idle , is that normal?
Check your throttle stop screw isn't holding the butterfly slightly open at the cut-off throttle position on your radio, if the stop screw is still in place.

I just remove the screw completely on my Walbro carbs.

The low speed needle also works way beyond 50% throttle. I have lost the Walbro tech sheet location but it is something like 80% throttle where the high speed needle comes into play on the 6xx series carbs. I'm sure the carb gurus will chime in with an accurate figure

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09-20-2007 01:41 AM  10 years agoPost 16
lperagallo

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Westfield, Indiana,​USA

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Ace,
Are you saying you do 3D and your heli hovers at 5 degrees of pitch? Most people doing 3D would be between 1850-2000 headspeed which would put you in orbit with 5 degrees of pitch. It produces 23.3 pounds of thrust at the rotors so do you have your heli weighted down with bricks? And if so, how much 3D’ing are you doing?
I run 1,550 headspeed in normal and hover at about 5 degrees pitch. I run a Bergen Intrepid that weighs about 13.5 pounds with fuel and battery. I also run 710 Vblades. And That's how it is. I don't try to figure out the pounds of thrust, nor apparently does my Heli because that's what it does. When I go to Idle up, I run 1,750 headspeed with the exact same pitch curve as normal from midstick up. Again there is no orbit.
Your throttle curve is flat??? That poor engine… and you want me to believe your headspeed is constant???
You apparently don't understand the term 'relative'. My curve is 10,18,21.5,31,94. That is relatively flat when compared to a nitro curve as I stated before. The combination of my pitch and throttle curve and Hansen 3Dmax engine seem to like each other and all run happy. While I don't do 3D, I do loops, rolls, flips along with general sport flying all with a -10,0,+10 pitch curve.

Maybe if you started flying and got practical experience instead of all your fancy theories and so called science you'd learn something. I burn about a gallon of gas or about three hours flying the gasser and three gallons sometimes more of kero flying the turbine each week , how much time do get in the air?

Lou

Twin Bergen 44Magnums FBL Wren NW44s - Kero start

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09-20-2007 09:26 PM  10 years agoPost 17
AceBird

rrElite Veteran

Utica, NY USA

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I run 1,550 headspeed in normal and hover at about 5 degrees pitch.
When I go to Idle up, I run 1,750 headspeed with the exact same pitch curve as normal from midstick up.
My curve is 10,18,21.5,31,94. --- with a -10,0,+10 pitch curve.
That’s just what I was looking for. So now we get down to reality.
Bergen doesn’t publish what their disc diameter is with the 720mm blades that come standard but I will say it is close to what the Predator is.

So if I plug the numbers into this wonderful spreadsheet we have 62.2 disc dia, 5 deg pitch, and 1550 RPM, results in 15.5 lbs of thrust. That’s not far off because it only takes a ½ degree lower in pitch to bring it down to 13.4 lbs. Now here’s the kicker, you flip the switch to idle 1 and you’re doing 1750 RPM which results in almost 3 lbs more of thrust! So out of the side of your mouth you claim you hover at ¾ stick. No way, no how. And what happens if you do burn enough fuel to start doing 3D. Crank that headspeed up some more and your hover point is going to lower again. So all this nonsense about having to learn a new hover point is exactly what you are doing.

You call this a flat curve? Not even your radio is going to be able to smooth out a 50 degree increase in slope right at the hover point as you say.

Now it’s my turn to give you some advice. You would learn something if you to go back to the fifth grade because a fifth grader could tell that the throttle curve is not flat on a gasser. And a fifth grader would know that “hover” is a state of equilibrium and sudden changes in slope of the throttle curve at the hover point would not be a good idea.

Back to the original topic:

Darko, if you have a desire to fly 3D some day and you want to start off learning with a symmetrical pitch curve then aim for a 5/8 stick position for hover. As you increase your headspeed (for different idle up modes) all you have to do is lower your pitch at the P4 position. This will increase your headspeed and also keep you near the 5/8 stick hover position. “Cheating” with the use of a governor will only increase the RPM and not change the pitch which will definitely change the hover point.
With a simple 5 point radio that has no expo you can attain a stable hover without having the rise be more sensitive than the sink because the slope of the pitch curve and the slope of the throttle curve is a straight line at the 5/8 stick position. Obviously 3/8 stick would be the inverted hover point on a symmetrical curve.
Some governors work better if the curves are closely matched to reality rather than have the governor do all the work. Whether it is science or whether it is common sense you will be better off learning the idiosyncrasies of matching curves early on.

If you have no desire for 3D flight and in particular your desire is AP then you don’t need to have 0 pitch at midstick. I would suggest setting your pitch for hover at midstick or below so you can get a very relaxing stick control around hover instead of being antsy. If you have your curves perfectly matched you should be able to attain a hover and flip to any of your other flight modes without upsetting the hover.

Ace
What could be more fun?

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09-21-2007 07:11 PM  10 years agoPost 18
darko

rrApprentice

Bosnia

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231 PUH setup

Manual and most of the guys said that the low needle should be 1 and a little above it ! In my case this needle is set under 1 maybe 6/8 and only in this position works well , if I put it to 1 I cand get the engine work properly as it is very rich . I use unleaded 95 gasoline with 1/50 Husquarna XP oil !
So what do you think about it ? Does anybody else have similar experience ?

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