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throttle adjustment problem
I recently assembled an Aeroworks Extra 260 50cc and put a DLE 55 in it. The plane has about eight flights on it and the engine has about one and a half gallons of gas through it.
When I first did the throttle servo setup, I adjusted my throttle stick on the transmitter to be completely down when the carburetor is closed. The throttle stick is all the way up when the carburetor is completely open. I noticed that when I'm flying, the plane seems to reach full throttle when my stick is only half way up. That means that very small movements of my stick at around a quarter throttle really affects how much the engine revs up or down. This makes it difficult for throttle control, especially when hovering. That also means I can move my stick around three-fourths throttle and it makes no difference on the engine since it's already at full throttle. Anyone have any ideas or comments? I'm hoping that when my stick is completely up the engine finally reaches full throttle. Thanks in advance. |
RE: throttle adjustment problem
the easy thing is to use exponential. The right thing would be to redo your linkage from your servoe to the throttle arm .
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RE: throttle adjustment problem
Thats the normal response of a gas engine to throttle. I set up a throttle curve in my 9303
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RE: throttle adjustment problem
What do you have the travel adjust set to at both ends of travel? The answer will determine what needs to be done from there.
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RE: throttle adjustment problem
For my throttle travel adjust, I have 32% for high and 95% for low. I'm using a DX7 by the way.
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RE: throttle adjustment problem
If you take a look at the link where i did a few posts on how to set the throttle to get the best mechanical set-up, it may be of some help ?
Let us know how you get on. cheers john http://www.rcuniverse.com/forum/m_95..._3/key_/tm.htm |
RE: throttle adjustment problem
ORIGINAL: 3daerofly For my throttle travel adjust, I have 32% for high and 95% for low. I'm using a DX7 by the way. Your linkage is way out of whack. |
RE: throttle adjustment problem
Ditto, Way outa whack.
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RE: throttle adjustment problem
I've been setting them up mechanically to where the travel at the carb is correct with the high end of the servo at 100%. The low end idle is less than 100% but at idle cut off the servo goes to 100%
Then I set exponential to get my throttle linearity the way I want it on the transmitter that doesn't actually have a programmable throttle curve On the other transmitter, the throttle curve is programmable. |
RE: throttle adjustment problem
Thanks for all of the tips. I will mess around with the linkage and update you guys on how it comes out. I should be able to work on it tonight and fly it sometime tomorrow.
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RE: throttle adjustment problem
Set you travels back to 100% Servo linkage on th innermost hole of the arm. Carb end on the outer most hole in the throttle arm. Before doing that, set both the servo and the carb lever at mid point. So the carb will be 1/2 open and the servo arm will be in the middle of the travel. The distance between the two will be the lenght of the linkage. Work with that and you'll be as close mechanically as you can get unless you have an extremely long carb lever arm. Those make things even better. Adjust travels at the transmitter after the linkage is at the right length. After that comes any curve adjustments.
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RE: throttle adjustment problem
I got the linkage adjusted and it's a lot closer, H: 58% L: 70%. There's no sub trim. I could see that the carb opens way smoother. My throttle stick lines up when the carb is all the way open and when it's completely closed. Also found out that DX7's don't have a throttle curve adjustment in acro mode. I'm thinking I can get a few flights in today if there's no rain. I should be fine for a while without any expo for the throttle.
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RE: throttle adjustment problem
Try to get the high at 100% and the low at 70 or 80%
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RE: throttle adjustment problem
Linkage is still to long for the arc radii.
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RE: throttle adjustment problem
HI SET UP your throttle so you have half throttle when the carb is half open-with end point (or atv ) be sure the carb is full open at full throttle-you should be able to cut the engine off by closing off the throttle trimon computer use the minus expotencial to slow the carbs movement to your personal liking-you did not have your throttle set as it s/bso i do see why it would be less than comfortable to run your engine ENJOY REGARDS TONY
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RE: throttle adjustment problem
1 Attachment(s)
As has been said by Tired old Man, Yon need to set the mechanical linkages to get even throttle %'s on bothe high and low. I have had to go through aan onther linkage to get the correct travel. Servo link is on the closest hole to centre and then I still needed to reduce it again in the angle to the carb as can be seen in the photo.
Cheers |
RE: throttle adjustment problem
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RE: throttle adjustment problem
Once the linkage length is right, I set my TX up with throttle travel being at 125% up and down, I move the connection at the servo, in this case a ball joint, inward toward the center, to the inner most hole on the arm. If the throttle arm at the carb has more than one hole, I use the outer most hole there for linkage. If you don't get your throttle travel up close to or above 100% as previously suggested by others, you won't have good resolution for precise throttle control. I set mine up for the max mechanical advantage (in at the servo arm, out at the carb arm) which also happens to promote best resolution when you setup your TX for the maximum travel you can get away with. It makes a really nice difference in throttle setup when you get things mechanically correct first.
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RE: throttle adjustment problem
Flew it twice today. The throttle response was definitely better but still was not perfect. Right now, I do have it set on the innermost hole on the the throttle servo and farthermost hole on the carb arm. I might add another linkage to see if that helps. Would adding some sort of extension to the carb arm help? The outermost hole (actually the only hole) is just less than half an inch out. The carb arm is not adjustable since it has a notch in it.
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RE: throttle adjustment problem
ORIGINAL: 3daerofly Flew it twice today. The throttle response was definitely better but still was not perfect. Right now, I do have it set on the innermost hole on the the throttle servo and farthermost hole on the carb arm. I might add another linkage to see if that helps. Would adding some sort of extension to the carb arm help? The outermost hole (actually the only hole) is just less than half an inch out. The carb arm is not adjustable since it has a notch in it. Use the "throttle curve" in the transmitter for the final adjustment ofthe response of the throttle stick. |
RE: throttle adjustment problem
ORIGINAL: 3daerofly Flew it twice today. The throttle response was definitely better but still was not perfect. Right now, I do have it set on the innermost hole on the the throttle servo and farthermost hole on the carb arm. I might add another linkage to see if that helps. Would adding some sort of extension to the carb arm help? The outermost hole (actually the only hole) is just less than half an inch out. The carb arm is not adjustable since it has a notch in it. cheers john |
RE: throttle adjustment problem
After a lot of installations, I've found that in most situations the carb linkage attachment point works out very good at 1" out from the throttle shaft. There are numerous ways to obtain a longer throttle arm at the carb. The easiest is to remove the one that comes on the carb and replace it with a nosewheel nylon steering arm from glow aircraft hardware. The wheel collar that fits the nosewheel steering gear is generally sized pretty close to the size of carb throttle shafts. Drill out a little if needed.
If you use a nylon servo arm it's quite easy to add one more hole between the servo output shaft and the first hole in the servo arm. Use Dubro 2-56 ball links for 4-40 rod at both ends of the linkage for the smoothest linkage operation. All of the above is keyed on having the correct linkage length. If you measure the length at any positions other than when both servo and carb are at the mid point, the linkage length will be wrong. Everytime. Gas carbs are not linear in operation in any event. Full throttle operation will be obtained when the throttle plate is between 75 and 80% open. That's what throttle curves and expo are there for. They smooth out that last 25%. |
RE: throttle adjustment problem
ORIGINAL: Tired Old Man After a lot of installations, I've found that in most situations the carb linkage attachment point works out very good at 1" out from the throttle shaft. There are numerous ways to obtain a longer throttle arm at the carb. The easiest is to remove the one that comes on the carb and replace it with a nosewheel nylon steering arm from glow aircraft hardware. The wheel collar that fits the nosewheel steering gear is generally sized pretty close to the size of carb throttle shafts. Drill out a little if needed. If you use a nylon servo arm it's quite easy to add one more hole between the servo output shaft and the first hole in the servo arm. Use Dubro 2-56 ball links for 4-40 rod at both ends of the linkage for the smoothest linkage operation. All of the above is keyed on having the correct linkage length. If you measure the length at any positions other than when both servo and carb are at the mid point, the linkage length will be wrong. Everytime. Gas carbs are not linear in operation in any event. Full throttle operation will be obtained when the throttle plate is between 75 and 80% open. That's what throttle curves and expo are there for. They smooth out that last 25%. |
RE: throttle adjustment problem
I second that http://www.rcuniverse.com/forum/js/f.../thumbs_up.gif
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RE: throttle adjustment problem
Would have worked out better if that 60 had been corrected to an 80 before I hit the OK button.....
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