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Synergy R/C Synergy N9 > Foaming fuel?
 
 
Droid
Elite Veteran
Location: Deep down in the Southwest- UK

Right this post is an assumption at the moment because i'm not back together yet to prove it.

On disassembly i found my lower main shaft bearing to feel gritty so i took the shielding off clean it and oiled it, felt the same, obviously my heli has been in but normally that affects top bearings and my top bearing is fine, and i went in nose first in throttle hold the blades had almost stopped when it hit the ground!

Being that this bearing is very close to the fuel tank and my tank doesn't foam until headspeed is up i think i might have found the little critter!!

I had dialled in the fan and high point balanced as most have and it made little to no difference to the fizzy fuel, and my motor was running sweet as prior to the incident!!

I can't comment on whether it was like it before i installed it as i cant remember even checking it then.

Any thoughts??

Those that can't stop the fuel foaming just check your bearings.

On a slight side note who has the new collet is it meant to be solid rather than split?? Mine is solid.

Will keep you all informed

Quotes may have been changed for my own amusement
09-21-2006 09:16 PM
 
 
Chuckie
Key Veteran
Location: Crofton Maryland, MHA member

Droid,

Here are my thoughts.

Did you check the balance of your main blades? If they are out they can cause low freq vibrations. It the tail blades were out or you had tail output shaft was bent you would have high freq vibrations.

I don't remember what motor you run but the OS does run a little rough if set too rich. Also, I've noticed on a friends heli the air pressure from the pump or YS crankcase can disturb the fuel and it appears to be caused by vibration. A test is to fly with only 1/4 tank of fuel and see if it still foams If not then the air pressure is probably the cause espically since you mentioned you don't have foam at low headspeed.

Even though your blades were not spinning doesn't mean the bearings can't be damaged in a crash. Try dropping an fueled 11lb model from 10 feet and see what damage occurs. Though I would agree that the top bearing would have taken some damage. Maybe the angle was just right to only affect the bottom bearing.

Charles

Please stand by for faster service!
09-21-2006 10:29 PM
 
 
bobc1
Senior Heliman
Location: Southern California

I did check the bearings prior to assembly. They were very smooth.

I've had no problems with my N9 in 21 tanks, so far...but, with respect to your fuel foaming issue:

I had been running 1690 normal, 1790 ID1, & 1920 ID2 with an OS 91 SZ PS/SB18. Fuel was very flat in normal & ID2 but was "waterfalling" in tank in ID1. I don't know if it was severe enough to call foaming & the heli sounded & looked very smooth, even in ID1.

I reduced ID1 to about 1740 & fuel is now very smooth in all modes. It just didn't seem to like the 1790 headspeed.

BTW, I changed to -40% expo to Normal,ID1, & TH (I am running -30% in ID2) & with the slower ID1 headspeed, it is much easier to practice slow flight & hovering maneuvers, both upright & inverted.

Just my $.02.

Bob
09-21-2006 11:31 PM
 
 
Droid
Elite Veteran
Location: Deep down in the Southwest- UK

I've never yet had to balance a set of Mah blades on any heli, i bolted them on first flight, never touched the tracking they were perfect. Tail had a little vibe early on but got better with tuning.

I run a non pumped szh and is my first experience with this engine ran YS's before, i must agree that it seems like the muffler pressure is airating the fuel (not that you said mufler pressure) but have run an MPII on a west 91 before and never had issues with muffler pressure airating fuel.

My only concern is not the foam in the tank but the build up of air in the header tank, i'd love to run a model without one but daren't do it till this is sorted, the proof of the pudding will be when it flies again maybe at weekend with new mainshaft bearings.

I think you misunderstood Charles, fuel doesn't foam until i reach headspeed is probably best way to describe it, i never run a low headspeed Its idle or Up!!

Quotes may have been changed for my own amusement
09-21-2006 11:38 PM
 
 
bobc1
Senior Heliman
Location: Southern California

Droid:

If the foaming is bad enough to introduce air into the header tank, that's way worse than my previous "waterfalling" fuel.

BTW, I'm not using muffler pressure with the OS 91 SZ PS.
09-21-2006 11:43 PM
 
 
Droid
Elite Veteran
Location: Deep down in the Southwest- UK

If you've seen picture of my heli you'll notice the round header tank, that is half empty after 3/4 tankful of fuel. The fuel in the main tank looks like its being sprayed into the main tank and turns like strawberry milkshake!

Quotes may have been changed for my own amusement
09-21-2006 11:49 PM
 
 
raptorheli2
Elite Veteran
Location: rip off britain and no changing it

it could be that bearing you refer to, i would rebuild with the new collet and see how it goes.

if you want to run without a header get a fuel magnet, i ran mine COMPLETELY dry last weekend and the tuning wan't effected once. i mean COMPLETELY dry btw.

i know people say they don't last long but i'm upto probably 25 flights with mine and it's still fine. the way i see it is, if i can get 50 flights per foam then thats fine by me, i change a glow plug every gallon which costs a lot more than that foam magnet. £3.50 per foam ish

cheers


www.waterfoothelis.com
09-22-2006 12:12 AM
HOMEPAGE  
 
 
j5coat
Veteran
Location: Phoenix

i am running the SZ with the clien mod and crankcase pressure. when you are hovering it you can see what looks like a wave in the tank, no foam just a wave. i was concerned at first and thought it was foaming but it was not. i asked jason about this and he said that it happens on his also. he said that the reason you notice this more in the synergy is that first off the tank is in the back, and second that the tank is made from clear plastic, not white like most other tanks. allowing you to see more of whats going on in there.

Trex 700, Trex 600n
09-22-2006 12:13 AM
 
 
Droid
Elite Veteran
Location: Deep down in the Southwest- UK

Just pulled motor apart and the bearings are going rusty already ive only had 2 UK gallons through it front doesn't feel smooth, i'm gonna swap them out with some ceramic/stainless high speed bearings i ordered at the same time as the motor (can't remember why i did that though ).

My R50 thats sat in the back of the garage for the last 9 months didn't look this bad inside!! ( and i never burnt the fuel off last flight either.)

Ah well it'll be like flying a new heli.....but it is new!!


Pinkies crossed.

Quotes may have been changed for my own amusement
09-22-2006 12:41 AM
 
 
raptorheli2
Elite Veteran
Location: rip off britain and no changing it

did you run the engine dry after use?

cheers


www.waterfoothelis.com
09-22-2006 12:55 AM
HOMEPAGE  
 
 
Chuckie
Key Veteran
Location: Crofton Maryland, MHA member

70 flights on my fuel magnet and it still looks good. I'll see how long it lasts. I'm running YS91 and Hator SB-16. O rings don't seem to last long as I have to replace the outside one every 20 flights. Not sure why. Last one I replaced was hard as a rock.

I always run my YS out of fuel at the end of the day. The magnet picks up every drop. I don't do full throttle climb outs with 1/8 fuel remaining as even with the magnet the engine requires too much fuel than can be picked up. I hover and look to see where the remaining fuel is and move the heli around so the magnet wipes up the fuel, lol. I don't really need a header tank. At 1900HS I get a little more than 10 minute flights, with a few autos at the end.

If I'm not going to use the YS91 for more than 2 weeks I'll take the back plate off and hand clean the motor with alcohol removing all fuel and oil. Any unburnt fuel in the motor will pull in moisture and rust the bearings. I'll then store the motor with run out oil. A few years back I waited three weeks and the main bearing was rusted.

Charles

Please stand by for faster service!
09-22-2006 02:11 AM
 
 
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Synergy R/C Synergy N9 > Foaming fuel?
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