mikes68charger

My Feedback: (34)

Ok I'm on my 3rd tank of fuel breaking in my DLE30

I'm a little perplexed. I set up the throtal servo to have full rang with the TX

So when the TX is at 1/2 the intake blade is at 1/2 and when at full power on the TX it just hits the wot stop on the carb

But running it up I don't need to give it more than 1/2 stick and the motor is revving as if at wot.

I'm useing a 18x6 to break it in

Also while running it at around 5k, ever few secounds there is a gargel sound. It dose not sound like a drop in RPM but a change in tone/almost like a pop or back fire sound. Is this normal?

Thanks

scooterinvegas

My Feedback: (1)

I have noticed that my gas engines are at about/around 75% power at 1/2 throttle.

My DLE's "burble" sometimes at half throttle. The low needle and high needle over lap in the mid-range. To get all the "burble" out, your low and/or high needle setting might get close to being too lean.

Tired Old Man

My Feedback: (1)

Google mid range burbal, throttle linkage set up, and gas engine tuning........

av8tor1977

My Feedback: (6)

Hee, hee...

(Sorry)

AV8TOR

krayzc-RCU

My Feedback: (31)

i run curves on my gassers to take that factor out of the mix.....

Campgems

the throttle is the servo Iuse the most expo on, just for the resons you mention. Get the end points where you want and then expo the curve to suit. Other than that, is is a lot of machanicla linkage adjustments. Don't get me wrong, the mechanics have to be right first or you are just chasing your tail. Setup with no expo and center the movements. IE Midrange on the TX stick is half throttle. Full throttle on the TX is full throttle on the carb without binding the linkage. Ditto on the low end. Once the mechanical setup is right, then the expo can work it's magic. Not before.

Don

mikes68charger

My Feedback: (34)

Thanks guys, I just read the gas motors for newbees.

I guess I need to take my fuel system out, I just put the gas fuel line over my brass tubes with zip ties, no barbs

IS there Exspo for throtal in a DX7?

Also the vibrations are makeing me go over the bird once more to make sure it can handle the shaking.

jedijody

My Feedback: (1)

Try this, it can help smooth out the throttle with geometry and require less fiddling with curves and expo. Get mechanical systems correct first, the fine tuning with the radio will be much easier afterward.

Tired Old Man

My Feedback: (1)

Zip ties without barbs works just fine. At least I hope so because I've been doing it that way in almost every plane I've had over the last 15 years or so. The only reason I mention barbs at all is to make the perpetual worriers feel a little better.

acerc

This is how I set up my throttle.
First, get the linkage as close as possible with the sorvo and throttle hole's, for best linear movent.
Now remove the servo arm, thencenter the throttleservo with theTx then center the throttle on the motor.
Now reattach the servo arm, go into the end points and reduce to o, or as far as the radio will allow.
Now move the throttle to down, no throttle, adjust the end point till the throttle on the carb is closed.
Now move the throttle to full and adjust the edpoint to get wide open throttle.
At this point I will start the engine up and make any adjustments nessary to the endpoints to obtain the best results.
By this I will obtain the absolute throttle off and full throttle with complete linear movement of the stick.
Most engines full throttle running is not with the carb wide open. So if you find that the middle of the power is above the middle of the stick
remove the throttle servo and move it one notch at a time towards throttle off untill you get middle stick = middle power then readjust the endpoints.
Of course for those that like using the throttle curve program, and has a radio with the capability, yes it is a lot easier.
I attatch my fuel lines to the fittins with a touch ofautomotive gasget sealerto the connector then slide the fuel line on. Not the silicone type but the rubber type.

My humble opinion thats all !

mikes68charger

My Feedback: (34)

Thanks guys for all the insite!

I cant wate to put this bird in the air,

So it seems the genaral opinon is to take out the idel screw so the servo can kill the motor, and not relie on the opto kill swich?

I kind of was hopeing to leave the screw in, and use the kill wich if needed. I already had the ball linkage pop off once while running her in the back yard, fix the issue, but if it ever falls off agian, I would rather the motor got to an idel so Im not dead sitcking it in.

scooterinvegas

My Feedback: (1)

The idle screw if different from the spring. The spring puts a load on you servo all the time, which makes it harder on the servo and draws more power from you flight battery.

Tired Old Man

My Feedback: (1)

Leave the return spring alone! If people were to measure the load from that spring they might finally discover the load to be negligible in the long run.

We've covered this ground many times before.

mikes68charger

My Feedback: (34)

Thanks guys, I know the spring is no issue, Im useing an old Futba S 148 servo, and there is no servo wine while holding the TX at WOT for several min. So Im not worried about the load, I just wanted to keep the ideal screw that way if something pops off, the motor gose to a idel not a dead stick.

Thanks Mike

Tired Old Man

My Feedback: (1)

Better to dump the idle set screw. The servo is the least of concerns. 148's are pretty reliable servos.

TheRickster

My Feedback: (12)

IF the linkage falls off I would rather the engine die than go to an idle.. The plane won't fly with the throttle at idle and more than likely when you land with it still idling you are gonna break the spinning prop... At least when it is dead it will windmill to the compression stroke which is normally 2&8 so you might not bust it.. Also if your DX does not have the expo for throttle you can also dial in some subtrim to make it bias one side..

Rick

BarracudaHockey

My Feedback: (11)

Nix the idle stop screw, let the servo do its job. You want to be able to shut the motor down with throttle trim.

Tired Old Man

My Feedback: (1)

This entire thread amplifies the need for the users to learn more about what they are doing. Just about every classic mistake for setting up throttle linkages has been described as being in use by someone that has posted in this thread. One thread describes a set up method that pretty much assures there will be issues with linkage linearity.

Idle stop screws are for lawn mowers and weedeaters. if you are flying one then you might need the stop screw. If you are flying an airplane or helicopter, even running a car or boat, ditch the stop screw.

qspilotcmh

I found this thread while searching for a solution to my DLE20 throttle curve.

Tired Old Man - What is your throttle servo setup procedure? I set mine up close to Jody's picture but not the same while the throttle is closed. I am getting 8100 RPM at full throttle and close to 7000 RPM at half stick. I can fix it with a throttle curve, however I would like to get the linkage setup real close then tweak it.

Thanks!

Tired Old Man

My Feedback: (1)

Gasser Throttle Linkage Installation and Set Up

Servo selection:

Use a standard sized servo. That's the initial basis of a good throttle servo. If you want precision, speed, and accurate throttle position every time, use a good coreless or digital servo. If you don't care about a wandering throttle position or difficulty in establishing a consistent idle, an analog servo will do. Servo quality is predicated on the choice of manufacturer and price. The low end servos provide low end performance and a lot of frustration. They don't center well, if at all, and rarely hit the same position for the same stick input twice in a row. You will be the one to decide what you prefer. Servo torque should be a minimum of 48 ounce inches. There is no maximum but 48 to 50 oz. in. is plenty for any throttle servo. Micro servos are a very bad idea. The Hitec hs225mg is as small as I would ever consider for a throttle servo. Metal gears generally last longer than nylon gears, and carbonite gears are noted for breaking when used with a gas engine. Nothing lasts forever. That should be enough for you to make a servo decision.

To start a linkage installation, set both the throttle servo and the carb lever to 50% positions. So the carb is opened up half way and the servo is at midpoint. Use a clamp or other means to secure the carb lever in position. Remove and discard the idle stop screw that may be installed on the carb when new. That's used for yard equipment that are normally operated at two speeds, idle and wide open throttle. Hopefully you use a wider range of throttle positions than just those

DO NOT remove or disconnect the throttle return spring. It's on there for several reasons, all of them good for what you want to use the carb for. If you are using a servo of a size suitable to be a throttle servo you will never have a problem because of that spring. If you are using a servo unsuitable for a throttle servo all the problems you will have were self-induced. You know how to fix that. Get a more appropriate servo.

Before going any further determine that travel adjust for the throttle servo is set at 100% both directions, no trims have been input, idle trim tab on the transmitter is fully closed, no mixes are in the radio, no rates have been set, and use the shortest servo arm that came with the servo. You will use the innermost hole on the arm. You may find you will want to make a hole inside of that one for best resolution. You will want maximum servo throw to provide minimal linkage travel. That doesn't make sense now but it will later.

Measure the distance between the servo arm and the carb lever hole. That's your beginning linkage length. Make the linkage and install using your favorite and safe attachment method at both ends. I'll suggest that at least one end be a bolt on ball link, that no pinned clevises be used, and if a pinned clevis is used it will be a metal pin with a secondary method of securing the clevis. 4-40 ball links can be a pain because of size and screw heads. Dubro makes a 2-56 bolt on ball link for 4-40 threaded rod. I'll let you look up the part number No metal to metal contact is ever allowed, although it's perfectly acceptable to use a metal or carbon throttle rod as long as it's electrically isolated from any metal levers or servo arms with something like a ball link. Zee bends in a metal rod connected to the carb lever will be a disaster. Don't do that.

Hopefully the carb lever is at least 1" long. you may have to change or modify the throttle lever at the carb. There are bolt on products available to complete that task. It's better if it's 1-1/4" or so because you want use an outer hole (farther from the throttle plate rod center) to obtain maximum throw at the carb end. You want an installation where the servo moves a lot to move the throttle plate a little, with the total rotation of the servo being enough to obtain full range of motion at the carb. The short servo arm with the long carb arm helps you do that. That's resolution of the finest kind since it does not require mixing and expos. Starting to make a little sense now?

If using a decent servo you can check the amount of throw from one end to the other and how that impacts the carb lever without powering up the radio. You should be pretty close and need only to increase or decrease servo travel a few percentage points to go from full closed to full open. If it requires that you adjust travels more than about 15% in either direction move the attachment point at the carb lever in or out on the lever to determine the effects. The linkage may still be a little too long or short. Also work with adjusting the ball link/clevis in or out a little bit. This is where making a new hole on the inside of the servo arm becomes helpful.

Ultimately you want the throttle plate to achieve a fully closed position with the throttle stick full back and the trim tab full down. THIS is the absolutely correct throttle stop/engine shut off position of the carb throttle plate because it provides full control of the throttle for idle trim and engine shut down. It also makes establishing your idle position extremely easy. Closing the plate will cut the engine every time. The trim tab will be what you will use to set idle throttle position. You can play with transmitter multiple idle positions later for those that like the idea of high and low idles. I don't, but some do. If you let the engine warm up before setting the idle it will likely be the same when you land as it did when you took off. That's another subject of its own.

You do not want the servo or the carb level to EVER hit a hard stop at either end. The carb will be providing the engine the ability to make 100% power long befere the throttle plate is fully open. The throttle plate does little for power/RPM after it passes somewhere between 75% and 80% open. That has to do with the plate and rod dimensions/geometry and it's impact on throttle fraction area. Don't worry about this because I'm certainly not going to write all that is required to define it all.

If your servo is moving a little and the carb lever is moving a lot, the linkage geometery and installation is totally wrong. You will always have trouble with throttle sensitivity when things work that way. You want a little servo travel to make a little carb lever motion, and to be able to use 100% of the servo travel to achieve 95%-100% of the carb lever movement without hitting stops. It's ok to use 100% or a little more or less of the servo travel, but it is never ok to introduce so much travel or linkage so long that any bind will be present. That kills servos in a big hurry, and drains flight batteries.

Hopefully the above will get you off to a good start and make throttle linkage on a gasser a bit easier for you to set up. Copy and past this post into a Word or text document on your computer for future reference. I did

w8ye

My Feedback: (16)

Throttle mechanical leverage diagram posted by jedijody

captinjohn

I gave TOM,s post a #5 rating. That is a very good posting on how to do the throttle linkage. Us Guys should be taking the time to at least rate a good post. Just think of the carefull thought Tom put into that post. We should be thankfull for all the postings that are made from very experienced senior folks ! Best Regards, Capt,n

ahicks

My Feedback: (2)

I think even the sharpest gas newbies will be surprised by the actual degree of "non-lineararity" of the carb opening to power availability when he finally figures out something's wrong with his setup.

That drawing, indicating proper throttle/servo arm geometry needs to be much easier to find/see to tip them off. May I humbly request that the power's that be make an attempt to include it in the newbie sticky at the top of the gas section?

w8ye

My Feedback: (16)

Will do

apalsson

My Feedback: (1)

Same here. Excellent post. Concise, to the point and covers all bases in one good document! [sm=thumbup.gif]