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-   -   DLE 20 Surging during throttle servo movement (http://www.rcuniverse.com/forum/gas-engines-142/10599078-dle-20-surging-during-throttle-servo-movement.html)

A&PMECH 06-29-2011 05:53 PM

DLE 20 Surging during throttle servo movement
 
Hi there guys,

I just finished a Balsa USA Citabria Pro and put a DLE 20 on it. This is my first gasser. I have flown it about four times now and everytime I bring the thottle back to shoot an approach the engine surges wildly then calms down to an idle. A fellow club member suggested that my throttle servo is too close to my ignition module. Any insight would be appreciated

Thanks in advance,
A&PMECH

All Day Dan 06-29-2011 06:20 PM

RE: DLE 20 Surging during throttle servo movement
 
Here's what Futaba has to say about the location of R/C equipment and the ignition system. Dan
http://www.futaba-rc.com/faq/faq-gas.html

rye 06-29-2011 06:29 PM

RE: DLE 20 Surging during throttle servo movement
 
hey
are you using a older radio or the new 2.4 ?

MetallicaJunkie 06-29-2011 06:44 PM

RE: DLE 20 Surging during throttle servo movement
 
is the throttle servo actually moving?

bcchi 06-29-2011 07:51 PM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: A&PMECH

Hi there guys,

I just finished a Balsa USA Citabria Pro and put a DLE 20 on it. This is my first gasser. I have flown it about four times now and everytime I bring the thottle back to shoot an approach the engine surges wildly then calms down to an idle. A fellow club member suggested that my throttle servo is too close to my ignition module. Any insight would be appreciated

Thanks in advance,
A&PMECH
Do you have,or can you borrow a DL 30 Ignition module. If so try that on your DL 20,and see how it runs with that.They have a different timing curve on the 20,Do not no why but RCEXL said this is what they wanted.If you can put a timing light on it you can see what it is doing.
Grumpy No two.

A&PMECH 06-30-2011 05:24 AM

RE: DLE 20 Surging during throttle servo movement
 
I am still using 72MHz. I can't tell if the throttle servo is moving. I guess I could un-cowl it to get a definitive look and check for throttle movement. I don't have access to a DLE 30 ignition module. I did take some measurements last night and the throttle servo is only 4 inches away from the ign module. I don't have a lot of room to switch things around. You guys think I should try moving the module as far awy from the radio equipment as posssible??

ec121 06-30-2011 07:20 AM

RE: DLE 20 Surging during throttle servo movement
 
I had a bad ignition one time that only messed up at full throttle. Max load is when the most interference is generated. Not going to say low speed won't do it, but it is more likely at full throttle. 4in isn't much but a lot of them have been done that close. You need to look at the servo for a definite answer. Sounds more like some sort of air leak. I had an ignition on a 3W 85 that would make a servo that wasn't even connected to the reciever jump. I just connected it to a servo driver and battery to make it hold, and then dangled it next to the the installed throttle servo with the motor running at high throttle. They both started jumping. Had to replace the bad ignition.

Tired Old Man 06-30-2011 08:22 AM

RE: DLE 20 Surging during throttle servo movement
 
Before making the call on what is doing what to what it might be considered "good form" to attempt simulating the condition on the ground where you can view the suspect components.

So far you have provided only speculation as to what might be occuring and so appear to be seeking a corrective action for an undefined problem. It's a fair guess since the first place an ignition feedback goes to is the throttle servo but you need to determine if that is indeed the case, then look further for the cause.

captinjohn 06-30-2011 09:07 AM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: Tired Old Man

Before making the call on what is doing what to what it might be considered "good form" to attempt simulating the condition on the ground where you can view the suspect components.

So far you have provided only speculation as to what might be occuring and so appear to be seeking a corrective action for an undefined problem. It's a fair guess since the first place an ignition feedback goes to is the throttle servo but you need to determine if that is indeed the case, then look further for the cause.
He provided speculation...because he does not know the cause...if he did he would not need to ask!

Whats this...

"good form"

undefined problem

It only took about 90 words to say....check ignition feedback first...may not be that.........................................

Tired Old Man 06-30-2011 05:15 PM

RE: DLE 20 Surging during throttle servo movement
 
John,

With all due respect, I also do crash investigations. The reason I bring this up is because part of that process is getting parts back and performing a full examination without tearing tings apart to attempt recreation of the event. If you can do that you can address the problem once. A one time fix instead of numerous attempts at guesswork.

So for this individual I'm suggesting, as politely and politically correct as possible, to attempt recreating the issue with a running engine, on the ground, with the plane opened up as much as possible, for viewing. Then, and only then make attempts to correct a problem you KNOW is occurring instead of taking a bunch of stabs in the dark and flinging the plane into the air with hopes of having the problem fixed.

With the exception of Metallica Junkie nothing printed so far in this thread implies ground attempts have been made to verify the problem, but most everyone has told him how to fix something as yet still an unknown. It's probably a loose spark plug cap but it may not be. It could be a metal to metal contact, and since at least one person in a DLE 20 thread suggested using a 4=40 rod with ell/Z bends for the choke rod... A bad ignition would not wait for throttle down and instead wreak havoc all the time. Same could be true for the throttle linkage. Fix something that may not be broken?

Plain enough?

ahicks 06-30-2011 05:37 PM

RE: DLE 20 Surging during throttle servo movement
 
I have to second T.O.M.'s thoughts regarding duplicating the problem on the ground. If you can, that should lead to a quicker repair? I hate playing the "try this" game.

If you can't duplicate the problem on the ground, and it's your first gasser, I'd suggest having somebody with gas experience look it over at the field? It might be something he could spot easily?

"Try this" game is a last resort for me. FWIW

jedijody 06-30-2011 05:40 PM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: Tired Old Man

John,

With all due respect, I also do crash investigations. The reason I bring this up is because part of that process is getting parts back and performing a full examination without tearing tings apart to attempt recreation of the event. If you can do that you can address the problem once. A one time fix instead of numerous attempts at guesswork.

So for this individual I'm suggesting, as politely and politically correct as possible, to attempt recreating the issue with a running engine, on the ground, with the plane opened up as much as possible, for viewing. Then, and only then make attempts to correct a problem you KNOW is occurring instead of taking a bunch of stabs in the dark and flinging the plane into the air with hopes of having the problem fixed.

With the exception of Metallica Junkie nothing printed so far in this thread implies ground attempts have been made to verify the problem, but most everyone has told him how to fix something as yet still an unknown. It's probably a loose spark plug cap but it may not be. It could be a metal to metal contact, and since at least one person in a DLE 20 thread suggested using a 4=40 rod with ell/Z bends for the choke rod... A bad ignition would not wait for throttle down and instead wreak havoc all the time. Same could be true for the throttle linkage. Fix something that may not be broken?

Plain enough?
Common sense is not so common anymore.http://www.rcuniverse.com/forum/js/f.../sad_smile.gif

A&PMECH 06-30-2011 05:57 PM

RE: DLE 20 Surging during throttle servo movement
 
Well to put all the bickering to rest... I have not had the time today to run the engine...but that's what I intend to do...on the ground with everything opened up to see what's actually happening. I hope the comment about common sense was not directed towards myself. I've been an aircraft mechanic for twenty years and I assure you, I have encountered much more difficult systems than this. I know all about radio interference, grounding issues and the like. I appreciate everyone's suggestions.

captinjohn 06-30-2011 06:19 PM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: Tired Old Man

John,

With all due respect, I also do crash investigations. The reason I bring this up is because part of that process is getting parts back and performing a full examination without tearing tings apart to attempt recreation of the event. If you can do that you can address the problem once. A one time fix instead of numerous attempts at guesswork.

So for this individual I'm suggesting, as politely and politically correct as possible, to attempt recreating the issue with a running engine, on the ground, with the plane opened up as much as possible, for viewing. Then, and only then make attempts to correct a problem you KNOW is occurring instead of taking a bunch of stabs in the dark and flinging the plane into the air with hopes of having the problem fixed.

With the exception of Metallica Junkie nothing printed so far in this thread implies ground attempts have been made to verify the problem, but most everyone has told him how to fix something as yet still an unknown. It's probably a loose spark plug cap but it may not be. It could be a metal to metal contact, and since at least one person in a DLE 20 thread suggested using a 4=40 rod with ell/Z bends for the choke rod... A bad ignition would not wait for throttle down and instead wreak havoc all the time. Same could be true for the throttle linkage. Fix something that may not be broken?

Plain enough?
Yes you are right....AM is not a good time for me to think very good....I am going to be a grumpy old man...partly because of my sinus problem in the am and sometimes most of the day. Sorry that I was not thinking good. Regards, Capt,n

MetallicaJunkie 06-30-2011 07:18 PM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: captinjohn


Quote:

ORIGINAL: Tired Old Man

John,

With all due respect, I also do crash investigations. The reason I bring this up is because part of that process is getting parts back and performing a full examination without tearing tings apart to attempt recreation of the event. If you can do that you can address the problem once. A one time fix instead of numerous attempts at guesswork.

So for this individual I'm suggesting, as politely and politically correct as possible, to attempt recreating the issue with a running engine, on the ground, with the plane opened up as much as possible, for viewing. Then, and only then make attempts to correct a problem you KNOW is occurring instead of taking a bunch of stabs in the dark and flinging the plane into the air with hopes of having the problem fixed.

With the exception of Metallica Junkie nothing printed so far in this thread implies ground attempts have been made to verify the problem, but most everyone has told him how to fix something as yet still an unknown. It's probably a loose spark plug cap but it may not be. It could be a metal to metal contact, and since at least one person in a DLE 20 thread suggested using a 4=40 rod with ell/Z bends for the choke rod... A bad ignition would not wait for throttle down and instead wreak havoc all the time. Same could be true for the throttle linkage. Fix something that may not be broken?

Plain enough?
Yes you are right....AM is not a good time for me to think very good....I am going to be a grumpy old man...partly because of my sinus problem in the am and sometimes most of the day. Sorry that I was not thinking good. Regards, Capt,n
it takes man size cojones to admit that..:D

MetallicaJunkie 06-30-2011 07:22 PM

RE: DLE 20 Surging during throttle servo movement
 
what servo are you using for throttle, just curious? im my glow planes i used to use the really old unimportant servos on my throttles.... i remember i had a similar problem one, all i did was swap out the servo and it was fixed.... i dont think your problem is as simple as mine but who knows?

Antique 06-30-2011 08:11 PM

RE: DLE 20 Surging during throttle servo movement
 
My educated guess is the goofy advance curve in the ignition...If it has a #4 on the front....
Like bcchi says, try a different RC EXL ignition...Could be part, if not all, of the problem..
I have ignitions with NO curve at all, straight 28 BTDC timing...I can send you one to try, just shipping charge...It might kick back a little when starting, but I will be anything you want to bet you won't be able to tell the difference between it and an electronic curve when the engine is running....
My first G26 conversions (before the chinese engine invasion) had NO curve, just straight timing at 28 BTDC...NO complaints from anyone...I only changed to RC EXL because just the parts for mine cost MORE than a complete RC ESL...I used some of ED Vollmer's syncro modules with my ignitions until he went out of business....Still the best ever...:D

RiverLarry 07-01-2011 02:03 AM

RE: DLE 20 Surging during throttle servo movement
 
Jedijody common sense left a lot of people a long time agao they dont teach it in school any more R/L

A&PMECH 07-01-2011 09:25 AM

RE: DLE 20 Surging during throttle servo movement
 
Ran the airplane with everything opened up and the throttle servo never moved unless I commanded it too. Moved the ignition module as far away from servos and receiver as possible and I still got the uncommanded surging.

ahicks 07-01-2011 09:43 AM

RE: DLE 20 Surging during throttle servo movement
 
This was on the ground or in flight?

Will it do this right away, or is this only after running WOT for a while?

Have you tried adjusting the carb (richened) to see if that might make a difference?

Original plug or CM-6?

Prop size?

a1pcfixer 07-01-2011 11:08 AM

RE: DLE 20 Surging during throttle servo movement
 
Try a different servo?

MetallicaJunkie 07-01-2011 11:46 AM

RE: DLE 20 Surging during throttle servo movement
 

Quote:

ORIGINAL: a1pcfixer

Try a different servo?
+1

Jezmo 07-01-2011 12:42 PM

RE: DLE 20 Surging during throttle servo movement
 
Before I wade into this I'm interested in the answer to the first two questions from Mr. Hicks - This was on the ground or in flight? Will it do this right away, or is this only after running WOT for a while? If it only does it in flight then I'm not leaning towards servo.

willig10 07-01-2011 01:13 PM

RE: DLE 20 Surging during throttle servo movement
 
He still has not answered the question of what # his ignition box has on it. If he ever ran the ignition with a receiver battery pack of 7+ volts this will also cause the surging. I bet it is either the ignition the one that Antique has mentioned, or the ignition has been over powered ( I did this before and the same thing happened I used a 7.5 volt receiver battery) this in turn took out the advance feature and the engine would surge. Changed the ignition and problem solved.

If as the OP stated that he ran it with everything opened up and the servo is solid. I strongly suspect the ignition module.

Glenn Williams


A&PMECH 07-01-2011 01:41 PM

RE: DLE 20 Surging during throttle servo movement
 
The run was performed on the ground with various throttle settings. It seemed to do it when the throttle was brought back to idle from power. I am using a 6V Hobbico Hydrimax 2000mah battery for the ignition as well as the receiver. I also am using a 72 MHz radio Futaba 4EXA radio with Hitec high torque servos for the flight controls(non metal gear) and a Standard Hitec servo for the throttle. I used Sullivan gold 'n rods (Nylon) with du-bro ball end connectors for both the throttle and a manual choke. 16x6 propeller and high idle was adjusted to achieve smooth transition to max power.


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