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Old Oct 24, 2012, 07:28 PM
The Twisted Elf
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USA, NJ, Trenton
Joined Nov 2010
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yes that would be the tunnel that everyone is refuring to.if you open a spot in the covering for heat to escape it will be ok to leave open but it should be closed if you are not going to
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Old Oct 24, 2012, 07:58 PM
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United States, NC, Greensboro
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RE throttle curve.....

it will all depend on how your throttle linkage is setup. Once you get it started up you will see what i mean.....easy enough to adjust by listening to the engine vs stick position .... you just dont want it hitting too hard right off the bottom.
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Old Oct 24, 2012, 08:00 PM
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Quote:
Originally Posted by lugnutz View Post
yes that would be the tunnel that everyone is refuring to.if you open a spot in the covering for heat to escape it will be ok to leave open but it should be closed if you are not going to

Okay cool! I have the piece on the belly with the v-slate pieces cut for ventilation and also were my vent line for the gas tank comes out. Like this:

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Old Oct 24, 2012, 08:06 PM
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Originally Posted by racerman27410 View Post
RE throttle curve.....

it will all depend on how your throttle linkage is setup. Once you get it started up you will see what i mean.....easy enough to adjust it to fit listening to the engine vs stick position .... you just dont want it hitting too hard right off the bottom.
Okay...right now I have my sub trim at (0) and my throttle arm and servo arm are at the same angle when at 0 or fully closed throttle. I know I'm going to have to add a few clicks on the trim to open the throttle to get it running/fired up. After that point is were I'm going to need to figure out the throttle curve. From what I'm seeing when I advance the throttle in relation to the stick movements... the throttle goes to full throttle (on the carb) before I get full throttle on the sticks. This is where I need to work on the throttle curve right? 100% on the sticks may be before the throttle arm on the carb get's to the mechanical end stop right? Am I understanding this right?
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Old Oct 24, 2012, 08:27 PM
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Originally Posted by RC_Feen View Post
] From what I'm seeing when I advance the throttle in relation to the stick movements... the throttle goes to full throttle (on the carb) before I get full throttle on the sticks. This is where I need to work on the throttle curve right? 100% on the sticks may be before the throttle arm on the carb get's to the mechanical end stop right? Am I understanding this right?

the engine is only going to turn a prop a max number of RPMs..that will vary depending on the size and pitch of the prop.
What i'm saying is you will get close to max RPMS well before you get to the mechanical stop. softening the curve (lower numbers at the throttle points) will let you have a more fine control over the RPMs in the lower range. IE not like a light switch from nothing to everything all at once.

Like i said once you get it started it will all make sense....
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Old Oct 24, 2012, 08:59 PM
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Originally Posted by racerman27410 View Post
the engine is only going to turn a prop a max number of RPMs..that will vary depending on the size and pitch of the prop.
What i'm saying is you will get close to max RPMS well before you get to the mechanical stop. softening the curve (lower numbers at the throttle points) will let you have a more fine control over the RPMs in the lower range. IE not like a light switch from nothing to everything all at once.

Like i said once you get it started it will all make sense....
OKay...I will be running a 18x8 break-in prop for the first gallon. So I'm setting up the needles for 1800rpms at idle. Then will I set the throttle curve to the max 9000rpm's that the engine is spec'ed at at the high end of the throttle curve? I'm sure I'll figure it out but just need to ask until I get to that point.
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Old Oct 24, 2012, 09:02 PM
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throttle curve will not affect travel. End points need to be adjusted so the throttle stops at the end of carb travel.
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Old Oct 24, 2012, 09:15 PM
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Culpeper, VA
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Originally Posted by going4speed View Post
throttle curve will not affect travel. End points need to be adjusted so the throttle stops at the end of carb travel.
Yeah..I have the end points setup already.
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Old Oct 24, 2012, 09:20 PM
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winston mo
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If you have your servo arm almost parallel to the servo body with the throttle closed. This set up works more closely to 1/4 stick 1/4 throttle, 1/2 stick 1/2 throttle an so forth.
Gas engines do equate to 1/4 throttle 1/4 of max rpm it's very unlinear.
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Old Oct 24, 2012, 09:44 PM
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The bolded part confuses me. Sounds like end points are too far past the stop on the carb.

Quote:
Originally Posted by RC_Feen View Post
Okay...right now I have my sub trim at (0) and my throttle arm and servo arm are at the same angle when at 0 or fully closed throttle. I know I'm going to have to add a few clicks on the trim to open the throttle to get it running/fired up. After that point is were I'm going to need to figure out the throttle curve. From what I'm seeing when I advance the throttle in relation to the stick movements... the throttle goes to full throttle (on the carb) before I get full throttle on the sticks. This is where I need to work on the throttle curve right? 100% on the sticks may be before the throttle arm on the carb get's to the mechanical end stop right? Am I understanding this right?
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Old Oct 24, 2012, 10:36 PM
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Culpeper, VA
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Quote:
Originally Posted by kerwin50 View Post
If you have your servo arm almost parallel to the servo body with the throttle closed. This set up works more closely to 1/4 stick 1/4 throttle, 1/2 stick 1/2 throttle an so forth.
Gas engines do equate to 1/4 throttle 1/4 of max rpm it's very unlinear.

Yes the throttle arm on the carb is parallel to the servo arm when the throttle stick is at 0 or the bottom.


Quote:
Originally Posted by going4speed View Post
The bolded part confuses me. Sounds like end points are too far past the stop on the carb.
I adjusted the end points for WOT to were the carb mechanical end stop just barely touches the mechanical end stop. What I did was moved the throttle stick to full throttle then adjusted the end point to the point were the carb just touches the mechanical end stop. Does that sound right or make sense? Isn't that setting the endpoint for max throttle?
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Old Oct 24, 2012, 10:47 PM
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winston mo
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I think your miss reading me. You do not want the angles of the carb an servo to match.
If they match, they move linear together. It's the mis matched angles that give the throttle it's exponential travel
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Old Oct 25, 2012, 07:23 AM
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Joined Aug 2012
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Just set up your linkage so that mid point on the throttle servo is approximately or as close as you can get to mid point on the carb butterfly opening. Then try to get your end points as close as possible to each other, approximately 100% each direction. Example you dont want one endpoint at 40 and the other at 80 This can be done by rotating your throttle arm, and by making your pushrod slightly longer or shorter (rotate the ball link on either end a turn or two as needed or messing with sub trim. On the DLE30 I have found it important to use the fiberglass extension provided on your throttle arm to lenghten in. Then move your ball link out on the throttle servo to about the third hole in the arm or an inch or so to start off, this should get you close. Move your ball link to the fourth or the second hole if too little or too much throw is obtained.


Then, when you are close on the geometry, test run your engine while you are breaking it in..go into the menu for throttle curve, and use a tach (get the Fromeco tach). I just did one on Saturday used the tach to determine rpm at each point on your throttle curve. For example, when I started I was at 7000 rpm at half throttle and 8000 rpm at full throttle...not what I wanted. When I finished five minutes later, I was around 4000 rpm at half and 3000 rpm at 1/3 and same 8000 rpm at full throttle, but I didnt hit 7000 rpm until over 3/4 throttle.

This is very simple and easy to do if you make your inputs on the screen while the engine is running and you have a tach to determine each point.

This is my simple method. There are more complicated methods to get the geometry right if you do a search but they were a little too complicated for me to understand and interpret. I have a good geometry and a linear throttle response to my stick inputs, and a good amount of servo resolution all as a result. I am sure an expert here will tell me a mistake in my process, but this simple method works good for me.
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Old Oct 25, 2012, 07:35 AM
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Thanks hooliganpilot...I'll give that a shot today! I'm going to build my plane restraint this morning so this afternoon hopefully I'll get the plane fired-up and start tweaking. Were you talking about this Fromeco tach? That's a bit pricey. I have this one to start out with. Thanks again!
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Last edited by RC_Feen; Oct 25, 2012 at 07:40 AM.
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Old Oct 25, 2012, 08:26 AM
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Culpeper, VA
Joined Oct 2005
692 Posts
More Questions!

I'm using a DX7 Tx. So if I'm going to use throttle curves I need to program the Tx using "Heli" as the model type right? I think this is right since this is the only way I can see the throttle curves.

Another thing. I'm see flex in the carb throttle arm. Is there a metal carb throttle arm available for the OS GT33? Thanks again everyone!
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