HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Nov 26, 2012, 11:24 PM
Registered User
United States, CA, Santa Maria
Joined Jan 2012
112 Posts
Discussion
DLE 30 vibration problems

i have a DLE 30 that vibrates pretty bad, i have tried 3 different props now, and even change the clocking of the prop to minimize the vibration. The engine is mounted on a 1/4 scale citabria, swinging a 18x8 Zinger. i got the vibration moved from the wing struts ( they vibrated very bad,, i thought they would break) to the tail feathers. 2 weeks ago i noticed a bolt wondering around inside the plane, so i found where one of the firewall bolts had worked its way out ( yes i used lock tight) so i reinstalled it with lock tight, and checked all the other bolts ( they were tight) and went flying this weekend, and when i got home, yet another bolt flopping around, further investigation revealed a broken bolt.... WOW.. soo, i was wondering if this is a common DLE 30 problem? and is there a fix?? soft mounts maybe.. let me know what you think..
bandit357 is offline Find More Posts by bandit357
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 27, 2012, 05:34 AM
Registered User
Kansas City
Joined Apr 2010
631 Posts
With all due respect, are you balancing your props?
Lifer is offline Find More Posts by Lifer
Reply With Quote
Old Nov 27, 2012, 09:20 AM
Registered User
United States, MI, Waterford Charter Township
Joined Aug 2008
1,326 Posts
Most nitro converts are amazed at the vibration levels encountered when going with gas, especially at first. That's an impression I remember vividly. It's most often worst at idle? Flying wires (and jury struts) are almost a necessity unless the tail surfaces are sheeted - even with the 20cc engines.

If the vibration doesn't smooth out, or increases as rpm's build up, you may have something else going on.

Agreed, prop balance becomes a big deal with gas. The props are bigger, and with vibration an issue already, anything you can do to help calm the storm is a good move.

Regarding your bolts loosening, I generally go over the plane pretty closely after those first few flights for stuff like you're describing. Have found that subsequent flights are generally a lot less trouble. After a while they settle in and are pretty good - but you'll still want to give them a good pre-flight. At minimum, check your control surfaces for excess movement/slop often! -Al
ahicks is online now Find More Posts by ahicks
Reply With Quote
Old Nov 27, 2012, 10:06 AM
Registered User
rjstrickjr's Avatar
United States, NC, Faison
Joined Jan 2011
683 Posts
What color of locktite are you using? I use blue on evrything metal to metal. If your having issues with it backing out maybe you should try the red locktite. Also don't buy the cheap stuff! The good licktite is only a few dollars more and compared to a high end gas model I would rather pay a few more dollars and let it live another day.

Make sure the props are ballanced. You can eather sand off a little on the back of the prop or use cear coat and apply it to the light side.

One more thing, has it ever had a prop strike or hit the ground in any way such as fell off the bench or droped?
Take the plug out and hold a straight edge as close without touching to the shaft or output of the engine. With the plug out it will turn easly. Look for any viriation of distance between the straight edge and the shaft while turning it.

These engines will bend the crank or propshaft if they hit. They turn at a high RPM and produce alot of heat therefore making them volnerable to bending if they strike the ground. The worst engine on the market for bent shafts is the G26 and G20. If they hit while running you can bet they have a bent shaft.
rjstrickjr is offline Find More Posts by rjstrickjr
Reply With Quote
Old Nov 27, 2012, 08:06 PM
Registered User
United States, CA, Santa Maria
Joined Jan 2012
112 Posts
more

thanks for replies, to answer some here, Yes the props have all been balanced ( 2 and 3 blade) what i have NOT checked yet is to see if the crank shaft is bent. this i suspect might be whats happening, the engine runs very smooth at idle, at mid range vibrates the most, and smooths out some at max RPM. i am really concerned because the engine mount bolt broke, this would indicate a high freq vibration. i have other gas engines and none of them vibrate this bad or break bolts. ( and for Loc-tight i use the red stuff)

the only way i have found yet to lower the amount of vibration was to clock the prop inline to the piston DTC, thinking the engine might be out of balance...

this week i will bring home the dial indicator and check the crank shaft.. i am still wondering if this is a problem unique to DLE???
bandit357 is offline Find More Posts by bandit357
Reply With Quote
Old Nov 28, 2012, 02:41 AM
Registered User
DarZeelon's Avatar
Israel, Ramat HaSharon
Joined Nov 2003
1,152 Posts
Bandit,


Any single-cylinder engine; even ones that were 'overbalanced' (Quadra by Dario Brigshegalia), are out-of-balance and will vibrate strongly, or a bit less strongly.

The crankshaft counterbalance, if equal in 'weight' to the reciprocating mass (the mass of the piston, the ring, the wrist-pin (and retainers where applicable) and the con-rod's top-end), will have very strong side-to-side vibration levels.
If it is equal in 'weight' to the con-rod's bottom-end (and retainer where applicable) only; i.e. no counterbalancing, the up-down vibration levels will knock the fillings out of your teeth.

So, it is customary to counterbalance the mass of ring, the wrist-pin (and retainers where applicable) and the con-rod's top-end; plus only half the mass of the piston.

This leaves both up-down and side-to-side forces at roughly half their maximum magnitude, bringing a similar reduction in vibration.
...And these are only primary vibrations (there are also secondary and tertiary order vibrations that are not dealt with at all)...

It can be said that the lighter the reciprocating mass; the lower the level of vibrations.

The DLE is not a very expensive engine, who's manufacturer can invest in making its parts as light as physically possible.

So, I guess you will have to live with it, taking all measures to prevent any other parts of the model from coming into heterodyne with the engine's vibrations; and 'compounding the pounding'...
DarZeelon is offline Find More Posts by DarZeelon
Last edited by DarZeelon; Nov 29, 2012 at 03:39 AM. Reason: Language.
Reply With Quote
Old Nov 28, 2012, 10:48 AM
Registered User
United States, MI, Waterford Charter Township
Joined Aug 2008
1,326 Posts
Quote:
Originally Posted by bandit357 View Post
thanks for replies, to answer some here, Yes the props have all been balanced ( 2 and 3 blade) what i have NOT checked yet is to see if the crank shaft is bent. this i suspect might be whats happening, the engine runs very smooth at idle, at mid range vibrates the most, and smooths out some at max RPM. i am really concerned because the engine mount bolt broke, this would indicate a high freq vibration. i have other gas engines and none of them vibrate this bad or break bolts. ( and for Loc-tight i use the red stuff)

the only way i have found yet to lower the amount of vibration was to clock the prop inline to the piston DTC, thinking the engine might be out of balance...

this week i will bring home the dial indicator and check the crank shaft.. i am still wondering if this is a problem unique to DLE???
Nothing I would consider excessive (when compared to other brands) in either of my DLE engines...
ahicks is online now Find More Posts by ahicks
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Wanted DLE 30 --- DLE 55 --- Saito 180 flyingstickers Aircraft - Fuel - Engines and Accessories (FS/W) 4 Jun 22, 2012 11:32 AM
Discussion Dle 30 running problems Crazy dogg Engines 0 Oct 30, 2011 08:06 AM
Discussion Vibrations on DLE 30 mikeochs Engines 6 Jul 10, 2011 06:06 AM
Question DLE-20 and DLE-30 have same Ignition? snoshoe62 Engines 17 Apr 22, 2011 03:52 PM
For Sale FS or trade DLE 30 for a DLE 55 scottiesoccer1 Aircraft - Fuel - Engines and Accessories (FS/W) 1 Oct 03, 2010 10:49 PM