RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1569 views POST REPLY
HomeAircraftHelicopterGasser Model RC HelicoptersOther › Engine Hammering Defined?
04-29-2010 11:24 PM  8 years agoPost 1
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

Somewhere in this forum a read a reference to "Engine Hammering" and the resulting destructive vibrations. Can anyone answer a few questions on the subject?

What are the symptoms of hammering?
What causes hammering?
Does a hammering engine make a particular sound?
How can hammering be eliminated?

I'm having some severe vibration issues and all the usual suspects have air tight alibis. When the ship begins to get light on the skids the vibrations will bounce her all around, resonance begins to build, and I have to come off the power immediately.

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 12:26 AM  8 years agoPost 2
Justin Stuart (RIP)

rrMaster

Plano, Texas

My Posts: All  Forum  Topic

What is this hammering you're talking about?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 12:47 AM  8 years agoPost 3
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

I had run a search on RR for Zenoah engine tuning. Someone had mentioned "Hammering". I may be reading too much in to the comment, but my take was that a poorly adjusted engine could enter a mode known as hammering, producing enough vibration to send parts flying.

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 12:49 AM  8 years agoPost 4
smallplanes

rrElite Veteran

S.C. ,SSA

My Posts: All  Forum  Topic

I like hammering as long as it's with a women. LOL I know what you mean i'm fightin the same problem right now on one of my helis. I would like to know also?

Thanks if any one can help us.
Ivan


Spectra G 26cc
Jewel
Bat 27cc
Trex 700<br

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-30-2010 01:39 AM  8 years agoPost 5
MarkToo

rrApprentice

Cambridge, ON

My Posts: All  Forum  Topic

Your shakes could be something as simple as blade grips unequally tightened - sounds stupid but, check 'em.

You say the usual suspects have been checked - what have you given the thumbs up to at this point?

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 01:41 AM  8 years agoPost 6
jschenck

rrProfessor

La Vista, NE.

My Posts: All  Forum  Topic

Well I've seen a gas engine 'hammer' like crazy when it was running lean. The fuel was litterally foaming up inside the tank, not just a layer on top of the fuel but the entire contents of the tank and sloshing around - like it was in a food processor. tail fins are in a high speed vibration state, landing gear is also fuzzy looking. All caused by carb bolts too long causing a lean running engine. I think what happens is when it gets too lean we get detonation causing the engine to jack-hammer on combustion - do that ~12,000/minute and you have a good vibrator

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 02:07 AM  8 years agoPost 7
Justin Stuart (RIP)

rrMaster

Plano, Texas

My Posts: All  Forum  Topic

So this is a detonation thing? Maybe you need higher octane fuel?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 03:47 AM  8 years agoPost 8
GREYEAGLE

rrElite Veteran

Flat Land's

My Posts: All  Forum  Topic

What's it Sound Like ???
Does's it go:

- PING pING Ping

- Bang, Bang,

- Clunkty Clunk clunk

- Sound like water hammer in your Pipes ?

Santa' Work Shop or Elv's in a tree?

How about a Video -

Could be anything from a broken clutch, spun bearing, tight grip's, loose mount, On and On

greyeagle

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 03:53 AM  8 years agoPost 9
Manol

rrApprentice

Hermosillo, Sonora, Mexico

My Posts: All  Forum  Topic

Ooooooh yeeeeessss these Gassers

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 04:52 AM  8 years agoPost 10
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

Think I found the problem...
I was doing a visual check of moving parts and noticed that the clutch bell did not track evenly through a complete revolution.

On initial assembly I had a difficult time establishing a smooth relationship between the main gear and the clutch mechanism. No matter what I did there was always a resistance spot during each turn of the main gear. After checking alignment and mesh I concluded that it would probably wear-in once the engine came to life. Wrong!

Too windy here today to fly anything but a very big kite so I took the time to remove the Predator upper frame set, which allowed me to remove the clutch assembly with shaft, gear, and both bearing blocks, intact.

I chucked the lower block in a vise with the upper block below, free to behave, or not, and the clutch bell above. Spinning the clutch bell by hand caused the upper block to do a hula. I was astonished at how much the upper block orbited the general vicinity of the shaft above. I then chucked the upper block in the same vise and dialed the clutch bell. One rotation wandered by more than fifteen thousandths.

Next I temporarily placed the clutch assembly back in the frames, this time without the main gear in place. Once the two bearing blocks were tightened within the frames the clutch became far less fluid, and produced the same cyclic resistance to manual spinning that I had encountered during initial assembly. It was obvious that confining the two clutch assembly bearing blocks to their assigned space was causing sever problems during rotation. I believe that those problems translated to massive vibration and ultimately resonance.

I removed the clutch assembly again, and pulled the shaft thinking that it must be bent. It is not. The clutch bell, lower bearing block and bearing come pre-assembled from Century. I have not seen a way to separate these pieces. I can only assume that there is an issue with how the clutch bell, lower bearing block, and lower bearing have been mated at the factory.

If you have had/fixed this problem please chime in. Thanks

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 08:50 PM  8 years agoPost 11
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

Yet another update:
Spoke with Paul at Century a few minutes ago. Half way through my description of the problem he identified the pinion gear as the issue and is sending a replacement.

It seems that Century received some kits with bad pinions pre-assembled to the clutch bell. Paul was not sure if the bad pinions were made out-of-round (tough to do on a lathe) or if the distortion occurred as they were threaded in to the clutch bell.

After the conversation I re-examined my clutch bell/pinion assembly, and Paul is right. Hold the clutch bell true and the pinion wobbles, hold the pinion true and the clutch bell wobbles.

Century was quick to respond, as usual.

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
04-30-2010 09:16 PM  8 years agoPost 12
flyinfriend

rrApprentice

North American continent

My Posts: All  Forum  Topic

Hi 2Tall,

I had the EXACT same issue. I caught mine in the build though. When turning the main gear it would tighten up at against the pinion at one point in the rotation. I removed the bell and pinion assembly and checked it closely. As I held the bell stationary the pinion would turn in a wobble and not centered. If I had run it this way I think it would have done a job on the frame mounting holes that hold the bell and pinion assembly.

I sent it to Paul and they replaced it within two days and he said it was a bad pinion. Someone on this site or the other within the last week had the exact same issue as well. I had quite a few quality control misses on my kit and Paul took care of all of them. I now have a nice flying Preddy but it was a nightmare getting there. I really hope Century can get their quality control issues ironed out with this kit. The service from Paul was ALWAYS excellent I just wish I hadn't need it soo much.

Good luck with your continued build.

Tom

PM  EMAIL  GALLERY  Attn:RR  Quote
05-01-2010 12:22 AM  8 years agoPost 13
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

Sites like RR provide us a great means to identify problems and share solutions. I wonder how many new fliers are out there trying to sort their way through these issues without any help at all. It's a bit scary.

I have often thought that the OEMs and/or distributors should offer safety of flight advisories via email to those of us who register our purchases. Paul at Century took the time to confirm my recent Predator purchase before our conversation moved on to a solution. With today's technology how hard would it have been to send an email to all those whose kits may have contained the problem pinion. Yes I know I'm dreaming.

An unassisted new pilot may not have recognized the building resonance. Continued attempts to fly would have certainly caused damage to the new ship and could easily have injured anyone nearby.

The OEMs may see it as less expensive to silently let the problem chips fall where the may, but the final tally could be much higher than expected. Just ask Toyota.

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
05-01-2010 12:57 AM  8 years agoPost 14
torque

rrKey Veteran

bolivia , north carolina

My Posts: All  Forum  Topic

i am going through the exact same problem. i won't get home until after may 10 and then i am going to call century and see if they can help me. i am so frustrated with the helicopter right now, i have it shelved.

PM  EMAIL  GALLERY  Attn:RR  Quote
05-01-2010 01:31 AM  8 years agoPost 15
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

i am so frustrated with the helicopter right now, i have it shelved.
I know the feeling. I hope that new pinions solve our vibration issues - my guess is that they will. You might want to consider emailing Paul through Century's technical support portal. The new pinion could be waiting for your return on the 10th.

Good luck...

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
05-01-2010 01:41 AM  8 years agoPost 16
smallplanes

rrElite Veteran

S.C. ,SSA

My Posts: All  Forum  Topic


Spectra G 26cc
Jewel
Bat 27cc
Trex 700<br

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
05-01-2010 01:55 AM  8 years agoPost 17
Peterr

rrApprentice

Queensland Australia

My Posts: All  Forum  Topic

At least you got " sold out " . we've got a turd here who's determined to GIVE Australia away to them ...

I wish these pollies at sometime had to live in the real world ......

But I know why I've got MA Spectra G's , at least they are american made ; there's zilch made here in Aus these days ...

E ,N ,G Whiplash's;Spectra G's;Stratus;E&N Razor,Fury 55;Furion6;TSA 600N, 700N, 700G;; Be

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
05-01-2010 04:37 AM  8 years agoPost 18
rbort

rrProfessor

Franklin, MA - USA

My Posts: All  Forum  Topic

Anyway, glad to hear you got it sorted. Once you get a chance to fly it let me know how you like things - I'm sure it will give you many hours of flying enjoyment once you get past the build/setup.

-=>Raja.

MA 1005 Hanson 280, 4225 flts
Spectra 27 3DMax, 3325 flts
Whiplash V1-2 Hanson 300, 1650 flts
Whiplash V2 Hanson 300, 504 flts

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
05-04-2010 02:12 AM  8 years agoPost 19
2tall

rrVeteran

Crystal Lake, Illinois, USA

My Posts: All  Forum  Topic

Great Service
Spoke to Paul at Century last Thursday and the new pinion arrived by mail today - thanks Paul for the quick response. Spent the evening putting things back together - just enough light left to run a quarter tank in the driveway at various RPM absent positive pitch - no vibration. Sweet at last.

On a lucky note: During reassembly I noticed that one of the small bearings at the end of the elevator A-arm pivot shaft was gone. That is not something I would have checked/noticed in a pre-flight inspection. Finding the problem now rather than during a post crash evaluation was not my usual fate. Just added another item to my pre-flight checklist.

"Pay attention...lest the ground rise up and smite thee."

PM  EMAIL  GALLERY  Attn:RR  Quote
05-12-2010 12:12 AM  8 years agoPost 20
torque

rrKey Veteran

bolivia , north carolina

My Posts: All  Forum  Topic

2tall, glad you got your pred. fixed. i sent century a email about the same problem. they won't fix it with out proof of purchase. i bought my heli. about 4.5 years ago. i don't have proof, so no support for me from century. i just replaced my clutch, clutch bell,bearing, lining, pinion and pinion bearing. i don't have the receipt for these either.

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1569 views POST REPLY
HomeAircraftHelicopterGasser Model RC HelicoptersOther › Engine Hammering Defined?
 Print TOPIC  Make Suggestion 

 10  Topic Subscribe

Tuesday, December 18 - 8:09 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online