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Old Nov 17, 2011, 08:45 AM
Complete RC Idiot Savant
The Netherlands
Joined Nov 2009
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@ Chophop: Braided shielding is allready there, and spark plug cap is of the full metal type, shrouding the full plug, and making ground at the same time (the unit even when loose on the table does not require a separate ground to get the plug firing, the braided wire forms the ground connection too)

EDIT: on my Zenoah powered helicopters, the spark plug lead is not even shielded.....

@crazy3dpilot: The firing angle is more or less fixed and should be approx 28 degrees (it is said somewhere between 30 and 26) before TDC.

Is just a matter of making a divided circle out of cardboard, and attaching it to the crank.
Find a good place for the sensor (with some room for adjustment). Use that circle to figure out where the magnet should be approximately on the propdriver (or similar crankshaft fixture) and afterwards, adjust the hall sensor so the plug fires when passing 28 degrees before TDC in the operating direction (the plug fires on two different angles, depending on direction of rotation, so use the correct direction).

Test run it, and see if you get improvement with a few degrees advancement or retardation.

It sounds simple but in my case was quite a hassle before I got it nailed.

For the RCeLX unit, you should better not get too much over 11000 RPM according my salesperson, as it is not designed for that according to him, but I can honestly not tell you how much is "too much".

Brgds, Bert
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Old Nov 17, 2011, 11:00 AM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
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confirmed 28-30 before TDC. look:
http://www.justengines.co.uk/acatalog/info_CDIINST.html
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Old Nov 18, 2011, 02:17 AM
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ciao FELN
nice project man, I have often dreamed a small gasser like that... but I dont trust very much a glow carb for gas, there is nothing better than a Walbro one. This is why the old Webra 150i did not get success, high temperature and glow carb. Some years ago I saw an OS.50 runing ethanol 80% and 20% oil or so...

I will clean my mind it's time to jumps to electrics I love the sound on scale fuselages...

someone in china is working on a 9cc gas engine for planes and helis later..

NGH GT9 , 9cc gasoline engine for areoplane (1 min 49 sec)


NGH GT9 (4 min 36 sec)
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Old Nov 18, 2011, 07:52 AM
no no no, a music gig
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Pleasant Valley Modelport
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Good, I thought it would work. Looks to me low octane fuel may be what a small motor needs, the combustion time is faster with low octane. When the stroke time is so short, the fuel may not have enough time to fully burn and expand. It will take a few tries to find that out. More octane slkows the cumbustion time down. But since high compression speeds it up, there may be a compromise. That's why there is a need to test octane. Too much octane will cause carbon soot and hard deposits.

Now remember I am a technician. My job is to find anything wrong with the work object. So I am not being offensive, but professional.

I think the prop is too close to the carb, a bounce or nose over could bend plastic props and snag it.

Overall, I am very happy with this news, thanks.
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Old Nov 20, 2011, 12:54 AM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
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Ciao Mikarro,
Thanks for your post.
happy to ear that NGH is working about gasser engine for heli.
Nice work on Raptor!.
To my Titan I add a carter for better cooling.

Yes as CHOPHOP say these conversion is a compromise but for me work fine.

CHOPHOP do you think the aeronautic gasoline AVGAS 100 LL would burn better? But as you, I know about lead deposits.
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Old Nov 20, 2011, 05:06 AM
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Denver, CO
Joined Dec 2005
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I run my gas engines at near 6000 ft altitude. I use 85 octane. The higher octane gas has not run well for me. Makes it hard to start, and runs rough. I have not adjusted the ignition settings, so might not be fair to the high octane.
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Old Nov 20, 2011, 05:35 AM
no no no, a music gig
Chophop's Avatar
Pleasant Valley Modelport
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From all I studied, high octane is for long stroke and high compression engines. Since you will be needing to read the spark plug, the high octane will probably make the plug black. 91 should be good. We use it in 450cc ultralight motors.
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Old Dec 29, 2011, 08:05 PM
no no no, a music gig
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Pleasant Valley Modelport
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I think the AV gas is a waste with the adjustable advance. The main idea of the lead is to prevent predetonation. And you would be breathing a small amount of lead in the fumes. Vey little but once in the body, it is very hard to get out. It stays. 87 or 91 should be good. You may very well get more power on 87.

Again, it is best to match octane to the stroke and compression. At high rpm the 87 would more surely completely burn and that means it should make more HP, and less fuel waste at top speed. Lots of misconceptrions about what the octane rating does.
Too low on the ocatne and you get detonation, meaning the burn quickly explodes instead of burning at maximum rate. The best bet is to time the burn so it keeps burning until the piston opens the exhaust port, and has a little pressure left to evacuate the burned gas. If it detonates then the expansion is over well before the piston reaches the port open part of the cycle.
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Old Jan 27, 2012, 11:14 AM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
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0s 50 hiper gasser conversion - titan 50 mx

one of us is working about this motor.
The motor is ready to run with gasoline.
Carburetor modified with two termal insulator in teflon.
By now the motor is well starting at low RPM but there is some difficult to find optimal RUN-IN at HIGH RPM.
The First TT53RL modified is well running at any RPM and has more than 25 hours.
My last TT56RL is ready on Titan. By now only 2 hours for Break-in and only hovering. Trying to find the right carburetor adjustments without problem, max cylinder temperature 140C . Gasoline with 10% oil.

Post the photos of OS50 for those interested to.
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Old Mar 10, 2012, 03:16 AM
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FELN why don't you try the NGH fuel pump ? it will maybe solve all your carb issues.
do you have any ring on the cylinder head ? you need it because the high compression of gas.
http://www.rcgroups.com/forums/showthread.php?t=1555659
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Old Mar 11, 2012, 01:41 AM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
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Quote:
Originally Posted by Mikarro View Post
FELN why don't you try the NGH fuel pump ? it will maybe solve all your carb issues.
do you have any ring on the cylinder head ? you need it because the high compression of gas.
http://www.rcgroups.com/forums/showthread.php?t=1555659
Hi Mikarro,
thank for the suggestion.
Yes I've an additional ring on the head cylinder.
My motor is a TT56 as you know and don't have a LINE from the carter of motor to pick up the pressure for the pump. Do you think I could use it from the muffler instead?
Thanks & regards
Claudio

PS: please where tu buy the fuel pump? I would try it!
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Old Mar 11, 2012, 03:34 AM
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ciao Claudio
you are using a 3D engine for that conversion, you should make those experiments with old engines...
yes you have to drill a hole on the carter (cover plate) or anywhere you want to get the pressure for the NGH system which works like a walbro carb.
you have to contact Mr. CHOW (NGH owner) he will tell you where to buy his fuel system without engine. You DON'T NEED the NGH carb, (too big for helis because it hits the engine fan) but any japanse carb of your engines will work much better. hope you get success because I want to convert all my heli engines as well.
just email him michaelchow2099@hotmail.com

question: could you post more pics ? where did you install the hall sensor ? do you use the same magnet for hall sensor and governor ?

forza Milan!
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Old Mar 11, 2012, 08:06 AM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
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Ciao Mikarro!
where do you live? do you understand Italian Language?
Ok! you are right about to use an old engine to experiment gasser conversion, some of my friend do it and said that the old engine return to nice power with gasser. My choice to TT56 cause I was not able to buid an insulator for the carburetor, the TT56 has it and is ready.
The Hall sensor is mount on an alloy plate on the back side of the motor mount frame, faced to the fuel tank. The magnet is fixed on one alloy ring (custom build by my friend) as NGH is. By now I have any photos and is difficult to do cause position from the tank and the mount motor frame. The first time desembarque the motor I'll do some photo to post.
About carburetor and fuel pump I would talk about, with my friend's team of heli gasser convertion and would try it Thank for the NGX link. When NGH would release a gasser motor for Helis .50 class ?
The governor GV1 is standby, I would link it when the motor and throttle curve is OK. I have two chance:
the first the is to share the Hail sensor
the second but not shure to solve is the RPM sensor line of the Excel ignition or the sensor of the Spektrum RPM sensor for telemetry with tx AR8000 rx DX8.
Best regards
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Old Mar 11, 2012, 08:25 AM
no no no, a music gig
Chophop's Avatar
Pleasant Valley Modelport
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You may want the carb to be a bit warm. On cool damp days ice can form in them and cause the motor to stop or melt down from a lean mixture. Full scale airplanes have a carb heat lever that diverts air over the exhaust to heat it. Part of the landing checklist to open carb heat. The problem is worst at lower throttle.
The small throat of model engines may greatly intensify the ice problem.
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Old Mar 11, 2012, 01:06 PM
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Quote:
Originally Posted by I-FELN View Post
When NGH would release a gasser motor for Helis .50 class ?
NEVER! they left the project because they have no knowledge about helis and aren't very interested about. The GT9 is a chinese .56 heli engine that they converted to gas with a longer cranckshat, they just don't wanna waste more time.
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