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Home✈️Aircraft🚁HelicopterBergen R/C Helicopters › Engine alignment : VERY important !
01-11-2006 02:55 PM  13 years ago
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jdewer

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Engine alignment : VERY important !
Ladies & Gentlemen,

For those who ever wondered whether the engine alignment in their Bergen is really that important, just look at the following image. The delrin insert were in that clutch for exactly one (1 ! ) flight of about 10 minutes. I thought my alignment wasn't too bad.....


oemèr, oeliver ! :-) Old flemish proverb.
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01-11-2006 03:33 PM  13 years ago
boomerang

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LOOK LIKE THAT THE DELRIN GET BATH VIBRATION!


Have a nice day.Nikos Boomerang
Nikos Katsoulis
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01-11-2006 03:57 PM  13 years ago
jdewer

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Nikos,

The vibration was not visible, if it was there at all.

To be resolved later....
oemèr, oeliver ! :-) Old flemish proverb.
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01-11-2006 05:06 PM  13 years ago
boomerang

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hum,....ik moet zegen dat het is 2 sorten of aligment.

Look to http://www.runryder.com/t206990p1/
Nikos Katsoulis
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01-14-2006 09:44 AM  13 years ago
nikos

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Hi jdewer


You fix your problem?


Nikos
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01-16-2006 01:41 PM  13 years ago
Jim Patterson

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That wouldn't happen to be a G-26 would it??Highly addicted to carbon fiber.....
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01-17-2006 02:26 PM  13 years ago
jdewer

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Jim, it is a G26 indeed. Why did you ask ?

The problem was clearly due to a severe misalignment between the clutch and the engine. I discussed the matter with Chris Bergen and he told me the procedure to avoid such issues.

If you're intrested, this is what he told me to do (If you read this, Chris, please feel free to comment or correct ):

First, make sure you loosen (spelling ? ) all screws, and I mean ALL screws of the engine, taking the two large ones completely out, and also the little bar holding the engine head.

Second, loosen all screws from the triple bearing block, making sure the bearing block moves freely ( no loctite blocking the movement).

Third, minimize the mesh between the main gear and the clutch, making sure the alignment is correct.

Fourth, pay attention to the clearance for the clutch ( drop the engine half a millimeter ), to allow the clutch to do it's work without stressing the bearing in the clutch.

Fifth, fully thighten the screws around the pull start adapter, effectively fixing the engine in the chosen position. Then tighten the screws holding the tripple bearing block.

After that, check the holes for the big screws in the side frames. If those need adjustment, enlargen them in the direction needed (shouldn't be more than a millimeter, if needed at all ). Same thing for the engine head support bar.

Put those missing screws into place, tighten fully and loctite each one of the screws.

Well, it seems simple enough, should be a piece of cake for everyone who passed the basket weaving phase with success.

I thought of a variation to that method, where first you put the clutch in a good position ( mesh-wise ), and then align the engine to the clutch, with the clutch already bolted down. This might even be better, because it is easier to align the clutch by itself, and then adjust the engine to that.

Until now, I haven't tried any of both, because I had to wait for the delrin inserts, winging their way to Belgium. They arrived yesterday (01/16/06).

BTW, Chris ( and in fact anyone at BergenRC ) is great in finding a realistic solution for any given problem. Thanks to you all !


Well, time flies when you're having fun, or discussing a great topic...

Kind Regards,


Jan Dewerchin.
oemèr, oeliver ! :-) Old flemish proverb.
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01-17-2006 02:32 PM  13 years ago
Gary Travis

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Utah

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Jan
Happy to see you have it worked out, several of the people I have helped were quick to blame such occcurences on the 260 puh engine. With proper alingnment and tunning these issues disappear. I have stated before that proper setup is the key. Hopefuly your posting here can help others who may be in the same position. Good luck!!
Gary Travis
Bergen R/C Helicopters Duralite Batteries DJI Innovations Magnum Fuels Wren Turbinesl
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01-17-2006 03:42 PM  13 years ago
Chris Bergen

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I think you've got it right, Jan. Let us know how it goes.Chris D. Bergen
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01-17-2006 04:27 PM  13 years ago
jdewer

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Just to be complete :

1°) Due to the possible movement of the engine during the lining up, one should check the throttle servo linkage. Things may be a little different then before.

2°) Before, during and after step five, make sure that the main gear spins around at least 1 and a half turns (480 °) when you spin it by hand. If not, check the mesh again & the tail transmission mesh & possibly the bearings on the main shaft & triple bearing block. Noise should be minimal.

I probably shouldn't be acting like I have something to say, here. After all, it's my heli having these problems .

Gary, just to be honest : I've doubted the G26 too, but the damage is so obviously due to engine misalignment that I will be keep that possibility until after I have chewed up all three sets of delrin inserts that Chris sent me.

Kind Regards,

Jan Dewerchin
oemèr, oeliver ! :-) Old flemish proverb.
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01-18-2006 09:27 AM  13 years ago
jdewer

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I have installed the delrin inserts yesterday evening,following the procedure. It turns out to be not so good. The problem is the part where you have to make sure the delrin inserts are well aligned with the clutch (it does seem strange that the delrin inserts should be algined with the clutch, after all there seems to be no way for them to move in any direction, but that's what the construction manual tells you to do).

If you just drop the engine and bolt on the new delrin inserts, and popping the thing back in, there is no way to make sure that the delrin inserts are properly aligned to the clutch.
So here's what I did :

1°) take the whole engine out.
2°) set the mesh right between clutch and main gear.
3°) tighten down the triple bearing block.
4°) remove the clutch from the triple bearing block.
5°) use the clutch as a guide to set the delrin insert right.
6°) put the clutch back. (Mesh is still good because the bearing block didn't move)
7°) put the engine back in, using the clutch as an alignment guide.
8°) tighten down the pull-start adapter plate.
9°) tighten down all the other screws.

I had no time to check whether it is good now, I'll have to wait until Saturday to find that out.


Kind Regards,
Jan Dewerchin.
oemèr, oeliver ! :-) Old flemish proverb.
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01-18-2006 01:34 PM  13 years ago
Chris Bergen

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Your "variation" may not give you the proper alignment, which is why I tried to make it very clear, which you posted earlier.

If you set the mesh without the engine in place, your VERTICAL alignment may be off. In other words the whole drivetrain MAY be tilted forward or backward, which means the mesh between pinion and main gear is at a tilt. It might feel good when you spin it, for now. But given a little time, about 1 flight, the top or bottom of the teeth (depending on which way it's tilted) will wear, and will probably eat up the main gear.

This alignment between the fan hub and clutch is NOT that critical. It's a visual alignment, but all the components must remain straight. If you can visually see that the fan hub and clutch are level with each other side to side and front to back, that should be good enough. Looking from the side of the helicopter, if the vertical alignment from the engine, fan, clutch, bell, pinion,triple bearing block, start shaft is straight up and down, and the gear mesh is smooth with minimal backlash, then it's good.

Another thing that can eat up delrin bushings is heat. Heat from the engine (running lean), or heat from the clutch (clutch slipping due to oil on the liner or too low of a head speed, or worn out liner).
Chris D. Bergen
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01-18-2006 05:15 PM  13 years ago
jdewer

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Chris,

In short : it still doesn't look good for my Intrepid.

The clutch must have gotten very hot at a certain time, because it's all blue. By itself, that shouldn't be a real problem, but it's clear that if the clutch has been hot enough to turn all blue, the liner in the cluch bell must have been at about the same temperature, effectively destroying it.

Any hints on how to replace the clutch liner ?

Kind Regards,

Jan Dewerchin
oemèr, oeliver ! :-) Old flemish proverb.
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01-18-2006 11:20 PM  13 years ago
Chris Bergen

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That's what I feared......

2 options, If you have access to a lathe, you can replace the liner yourself,(it requires turning down to the proper diameter)

Or send it to me, for $20, I'll reline it and send it back.

I should have picked up on this possibility sooner, we could have had it done already.

I seem to remember you went through a time where you were taking out main gears. The same thing would cause that.

What headspeed had you been running? Is there any oil soaked into the liner?

Check the clutch by looking at the "shoes". If they aren't sprung out, it's probably OK. You can tell by looking at the slit, it should be uniform in width from the hole to the edge of the clutch.

Measure the diameter of the clutch, NOT on the shoes, but on the solid area of the clutch. Now measure the inner diameter of the liner. The difference between the two should no more than .016", giving a maximum clearance between clutch and liner of .008".

It is possible the liner is OK, just may need cleaning. Let it soak in alcohol (NOT Jack Daniels), then wipe it with a paper towel to remove the oil. Let dry and see if it then works properly.
Chris D. Bergen
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01-19-2006 04:38 PM  13 years ago
jdewer

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Chris,

I hope the following tells you something about the state of the liner ?

Kind Regards,

Jan Dewerchin

oemèr, oeliver ! :-) Old flemish proverb.
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01-19-2006 04:42 PM  13 years ago
jdewer

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And here's an other one from the clutch itself :

The slit looks even over the whole length on both sides, no ?


oemèr, oeliver ! :-) Old flemish proverb.
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01-19-2006 05:02 PM  13 years ago
Chris Bergen

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Clean the liner, then measure it as suggested previously. The clutch looks OK, I don't really like the Blueing at the hole/pivot point.Chris D. Bergen
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01-20-2006 03:52 AM  13 years ago
Jim Patterson

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To jump back in and reply to your question. I only ran a 231(stock / unmodified) in my Intrepid, and I didn't have any vibe related problems. But,, I've tried the 26 in a stock 1005 X-cell, and a Spectra G. Neither of these machines cared for the 26. In the older X-cell gasser (1005) it lifted off in the first hover as smooooth as glass and was ok in forward flight, but one flip and it almost shook itself to death before I got it down. There's not enough structure to support this beast in this heli.(actually broke the front of a skid off) I tried re-alighnment 3 more times with the same result, (more locktite, feeler gauges, etc) and finally put the stock 23 back in, all is well now. Pretty much the same thing with the spectra, only not as violent, mostly shows up as clutch / bearing damage.

I just got a lightened piston to try in the 26, to see if I can tame it a little. I think the 26 is basically out of balance, (same bottom end as a 231 with a heavier piston and of course a stronger power pulse).

My appologizes to the Bergen folks but I think this is all related. There are success stories with the 26 as well, so who knows for sure??
Jim
Highly addicted to carbon fiber.....
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01-20-2006 04:36 AM  13 years ago
Chris Bergen

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No apologies are ever necessary here, I want and need the feedback that gets presented here on RR. It keeps all of us honest!

Here are my thoughts;

The vast majority of the Intrepid gassers out there right now use the G26. Most of those are unmodified ones as well.

All of the new Observer EB's and quite a few of the Belt drive Observers also use G26's.

In the Intrepids, the vibration issues from the G26's that others(MA and Century) have reported are not typically a problem. I don't know if it's mounting arrangement, the use of G10, our higher oil recommendations, or a combination of all of the above. Is the balance of the engine incorrect? Yes it is. We measured the pistons over three years ago. I know everyone has their own way of doing things, their own theories on how things SHOULD work, But what I also know, is that if our recommendations are followed in our helicopter, it will work. Not everyone is willing to do so, so not everyone has had success.

Jan's issues with the delrin bushings are NOT vibration related. They ARE heat related as you can see the bushings are melted, and the clutch is blue, which is a sure sign of heat. Now we have to determine why they got hot enough to melt and turn the clutch blue. This tells me the clutch was slipping. 2 things will cause that, oil in the liner, or too low of a headspeed/engine RPM.

These troubles are not new, and we have made changes to try to prevent them. All bearings that are put in the clutch bells at the shop now have the oil and/or grease removed first. We have also slightly changed the RPM(lower) at which the clutch engages on the EB versions.

Try the G26 in your Intrepid. Run regular gas (87 Octane) and 5 oz of synthetic oil. Set your needles at 1 3/8, load the engine at the proper RPM, and she will be smooth. If you have air leaks, or other difficulties, then those need to be fixed as well.
Chris D. Bergen
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01-20-2006 09:38 AM  13 years ago
jdewer

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Belgium

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Hi Chris & Jim,

Due to the fact that I can't compare to other machine / gas engine combinations, I will not add anything to the debate. Just these facts, maybe :

Some well respected scale pilots at our local club consider switching their engines in their machines from G321 to G26, after seeing the Intrepid and a thorough inspection of engine and gearing. I know for a fact that one already has, he's using it in a Vario MD 900 explorer. He needed the extra punch for the NOTAR system. These guys make no compromises on quality, so the engine must be good.

Every gas pilot at the club warned me about the G26 : how difficult it was to set it right, horror stories about vibrations, overheating and what not. It took half an hour on a Sunday morning to set my engine correct, using the instructions Gary gave on his DVD (Yes, I took notes). There are NO VISIBLE vibrations (tail, skids, pull-start handle, whatever), the engine response is great with tons of power (never do a full collective stab without warning people around you). Anyhow, this convinced the scale pilots to recheck their setup, and with great results. ( I turned from a gas - rookie to a gas - guru in half an hour ).

My troubles with the Intrepid will most probably be related to grease or oil getting into the clutch-bell. When I did the first flights with the EB, I had no means to check the head speed, and the clutch was always too hot to touch afterwards, indicating a head speed that was too low.
I think this heat made the lower bearing pop open (perhaps it was an older bearing) and the grease got directly in the clutch bell, making things even worse.

The first flights I had at the field, with someone to check the head speed, it only got to the 1450 - 1500 RPM range after a very long spool-up, where all of a sudden you could hear the engine regime dropping, and the blade noise getting a lot stronger, and then it was ok. This behavior was not normal, but hey, it flew. I had no idea I was toasting the delrin inserts.


Now, back to solving the problems at hand.

Chris, I soaked the clutch for 3 hours in alcohol and wiped it clean like you said. The tolerances are within specs (checked on four locations around the clutch bell ).

I will re-assemble the EB this evening, taking your instructions as a guideline.

I'll post the results after the weekend, unless something marvelous or disastrous happens.

Kind Regards,
Jan Dewerchin
oemèr, oeliver ! :-) Old flemish proverb.
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