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Home✈️Aircraft🚁HelicopterThunder TigerOther › Throttle curves at raptortecniques
09-06-2006 03:09 AM  14 years ago
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bostonheli

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MA-USA

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Throttle curves at raptortecniques
At http://www.raptortechnique.com/throttlecurve.htm

It is suggested to have the throttle curve for normal mode for 50 size engine like this

20, 30, 40, 50, 80

I have a hyper 50 engine, and at 20%, the blades are already spinning. If I set the curve like that, right after starting up, the blades will spin like crazy on me, no?

My current throttle curve in normal is like this:

1.5, 15.0, 28.0, 55.5, 82.0

I must be misinterpreting the page. Any input?
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09-06-2006 03:23 AM  14 years ago
jsenicka

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Eagle River, WI

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explained above in same section

If you are just starting out then normal flight mode is the only one you need to setup. When I setup this mode I start with 20,40,50,60,100 for the five points of the throttle curve. The bottom point is set to 20% for radios with a digital type throttle trim. If the radio has a mechanical trim then I set the bottom point to 0%


You would use the trim to get it to idle with blades stopped
Jim Senicka
Team Manager, GrandRC Flight Team
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09-06-2006 06:30 AM  14 years ago
firefox

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Thailand

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The page assumes that you are not trimming the throttle for idle, and that the throttle linkage is setup properly, and that you're using a fairly modern programmable radio. In this type of setup, 0 is actually a totally closed carb, and 100 is a totally open carb.

If you had used a curve starting with 1.5, then when starting the engine (and the throttle stick totally down, as it's supposed to be) the engine would never start, since the carb is nearly completely closed. Even if you managed to get it to start, any time you moved the throttle down completely your engine would die.

The suggested curve starts at 20 (or around 15-25, depending on your setup) since that's where nearly all engines start to idle. Anything below that and the engine dies. If somehow you set up your linkages wrong, and it actually does idle at 1.5, how do you get it to cut? 1.5 and 0 are hardly any different, so unless you've got throttle cut set to negative (which means you've got it setup wrong) then you're never going to manage to stop your engine.
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09-06-2006 04:32 PM  14 years ago
bostonheli

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Thanks for all the inputs,

I currently have a "kill" switch that completely closes the carb to cut the engine, so at 0% throttle stick, the engine does not die. This is my throttle curve in normal mode:

1.5, 15.0, 28.0, 55.5, 82.0

My pitch setup is

-2, 2, 5, 7, 9

Is this setup okay?

Raptor 50SE hyper engine, gv-1, 401/9254
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09-06-2006 04:47 PM  14 years ago
firefox

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Thailand

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If it works, then it works. It's just not the normal way of doing things.

Basically, if your throttle curve were a straight line, from 0 to 100, then at lowest stick/position, your carb would be completely closed (cannot move the carb arm any more) and at highest stick it would completely open (the other way around). Of course, this means that at lowest stick (zero throttle) your engine would die, since pretty much all carbs will idle at around 15-30, not 0. The "kill" switch (throttle cut) is for this purpose, to put the throttle *link* at zero, so that you can have a throttle curve that's a line from 15-30 to 80-100. Right now, your "kill" switch probably has the servo going negative (probably -15, -20), beyond the normal range, and that's not the normal way of setting it up.

Pitch is OK.
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09-06-2006 05:19 PM  14 years ago
jsenicka

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Eagle River, WI

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on 9C, I need to set bottom at like 14 percent to make idele.
On my 9ZWC2, I set bottom to 0% and set idle with trim.
Depends on the radio model guess
Jim Senicka
Team Manager, GrandRC Flight Team
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09-06-2006 07:46 PM  14 years ago
702nitro

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Las Vegas, NV

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Another thing you might want to consider is Headspeed. If the head speed isn't at least 1600rpm, you'll noticed that the heli will wobble/shack or fight itself to keep itself up within that given pitch and throttle point. Have someone tach the blades, if your head speed is below 1600 you'll need to increase point 3 of your T-Curve.
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09-06-2006 09:04 PM  14 years ago
zipphreak

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Attleboro, MA

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I have my throttle curve for normal mode setup so :

at 0% throttle low stick, and my mechanical throttle trim pulled to the bottom the carb is completely closed.

at 0% centered throttle trim, engine idles for starting purposes.

at 50% the carb is half open.

at 100% the carb is fully open.

Luke,

Feel free to get me on irc later tonight if you have questions on the setup. You need to get your setup finalized, and that tank patched so you can start concentrating on flying

A tach is ideal for setting up your throttle curves, without it your flying with a pilot basically. Although some can do it by ear pretty decently, most can't.
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09-07-2006 04:55 AM  14 years ago
skyad

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sudbury,on,ca

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first manually set up your thr end points if not using a gov between 60 and 80(if using gov they suggest 100 and 100 ) both high and low points the same, rod lenght should be the same distance as between the ctr of thr servo and carb thr lever.that done set your low point so the engine idols just before clutch engages set mid point (no.3)so that u have the head speed u want for hover (1600-1750)use optical tac set high point so you don,t bog in full climb out (and not so high that it over speeds.now set point 2 between 1 and 3 and point 4 between 3 and 5 all done .
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09-07-2006 04:59 AM  14 years ago
jschenck

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La Vista, NE.

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Once you have a good idle set, take note where the throttle barrel is at. The OS engines have marks on the barrel and carb body. From then on anytime you make a radio change you can use that to get the idle set close. Do the same for the rest of the throttle curve once you have it tuned close to where you like it.

Basically what I'm saying is the radio settings are only a guide - you need to make sure that the mechanics make sense. This is true with all the controls, not just the throttle.

btw - the norm I've seen is to setup the throttle so that 0% is barrel close (bottom mark) and 100% is open (top mark). I find that the mid-stick position on my R50/Hyper should be just a little less than the middle mark on the barrel flying 0 pitch at mid-stick. Once I have this idle will be somewhere in the 15% to 20% area.
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09-07-2006 09:35 AM  14 years ago
dragonlord

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luton uk

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first thing to do is get the geromitry right on the linkage
ie 0 in closed 100 is fully open and 50 is really 50

so it spot on

to do it on a os hyper is really easy as if you look a the barrel the center is marked on the hyper

stot off by setting your curve to 0 25 50 75 100
and endpoints to 100

center all trim and sub trim on radio turn on reciver and radio

put stick to center ie 50% ponts unscrew trottel servo horn and oput back on so pull link is pointing strait to ground.

lossen trottel arm on carb and retighten it and aline it so when barrel in at hald trottel it pointing strait down same as servo arm

now make up balllink arm to fit

now check and ajust endpoints so the no binding at full or closed trotel

if you done it right you endpoints will be perfect

now set you curv to about 13 on bottom point start up and ajust botome point to just a touch below where cluch engages


this will probly have to come down a bit lover when you lean out a bit


then just spoolup and to about half trottel and reduce mid point untill you head speed is about right by ear


with a hyper 50 and a futarba 9c super my normal mode works out at

8 22 42 65 100
not that i do much in normal mode other than start it up
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