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Petrol Engine Set Up

Started by Bad Raven, September 08, 2018, 18:20:38 pm

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Bad Raven

OK, so now I'm a long LONG way out of my comfort zone.

Seagull Zlin 50L ARTF, but I'm fitting a 20cc Petrol engine.   I do have one petrol plane (Extra, 26cc Zenoah (magneto), bought secondhand and never worked on other than a replacement carb gasket.

So, I have the kit supplied tank (for 91 glow it looks small, but then it is going to be feeding a 20cc petrol with that's lower fuel consumption).

I have a replacement petrol suitable end bung, tubes, etc that fits the supplied tank so no need for mounting issues

I have a felt anti foam clunk, which seems very light despite having a weight inside its cage.  No way will any of the petrol tubing I have allow that clunk to follow the fuel.

What do I use for the in tank tubing?

How do I isolate the ignition (kill switch), is a normal RC switch on 4-6v input supply sufficient?

What is the best tank piping method, three pipe:-  feed, carb, open vent?  I'm thinking of two pipes exiting the cowl in the under air vent space, fill and open vent (when working).

Anything else re plumbing and wiring for petrol please?
The user formerly know as Bravedan........... Well if Prince can do it....................

ludwig

Could be an interesting thread, there is a lot of miss-information out there.

Charlie C

Don't know if this helps, but all my petrol models, 20cc to 120cc, are set up this way.

For 20cc, the smaller bore Tygon tubing will be fine. If you fit brand new genuine Tygon in the tank, you will find it is very flexible and with the addition of a fuel soaked felt clunk will have no issues picking up the  fuel.

On the tank i recommend a three pipe set up. One each for fill, vent and fuel supply. I also ensure that the pipe end fittings cannot move or leak by wire locking them. I also try to use metal bung compression fittings if i can as you can easilly overtighten plastic ones.
Also, when iv'e finished flying, i fill the tank up to about 3/4 full, bung up the vent and the fill lines and leave the throttle open a little, say an 1/8 of the movement to keep the carb diaphramme wet.

On the ignition side, i use an opto isolater or kill switch, which is wired into the reciever and the engine ignition line. They also have an LED indicator so you can set up a switch on it.
If its a mag engine, just set up a posative switch actuated throttle cut on the carb throttle butterfly.

Others may not agree, but it works for me and all the petrol powered models in my club as we all have the same set up.

Hope that helps

Charlie C

Global Moderator

fokker

Much the same as Charlie. One pickup and 2 vents usually underneath and behind the engine . Vents made from either commercial fittings or soldering copper or brass tube to a bracket screwed to f1. I join the breathers with an offcut of Tyron  stops the smell and any spillage during transport and storage . If possible put the tank on c of g remember your carb is pumped so no problems with starvation. On a 20cc I'd go for an 18 or 20 oz tank and 3/32 tubing. Keep your vent pipes as high as possible again help stops spillage I will often pass them over the top of the standoff's.
For stopping the engine I use a rcxel opto kill switch or on a mag engine set the trainer switch as engine kill.

Bad Raven

Thanks for replies so far.

I should point out that I have only once seen another petrol engine user at my club, and I think he moved clubs as he built a plane too heavy and large for our location.

The engine I am installing is electronic ignition. The only petrol I have (which I did not build) is old and Magneto. I have not used this magneto model very much and with long periods not used I have found the carb diaphragm failed, needing a new diaphragm fitting, so quickly gave up using it.  ( Its heavy and so its landing requirements are also a bit "long" for our tiny patch).  I had not thought of keeping petrol (fumes) on the diaphragm, but I had never emptied the tank after use, though not opened the throttle.

Have just ordered a rcexel Tx operated kill switch. Is this sufficient alone or is a manual on plane switch also required? (presumably series wired in ignition feed if so)

I have not even looked at engine orientation yet. Presumably inverted to keep cowl top and sides mostly intact.

I have plenty of new 3/32" tygon from two sources (one Sullivan)  but both seem too stiff for a clunk tube!  (though felt not wet of course).  Over 100mm, more than in the tank, the clunk has NO effect on the tube direction!!

Introducing a third variable, Exhaust "silencing"?  The site it will be flown is quite noise sensitive. I realise this is very subjective, but I need to keep the noise at or below a SC 91 powered "Panic" that rarely goes over half throttle to do all its extreme stunting in the air with a low pitch prop.      I'd rather an ugly plane than a lost site. What do you use?  Commercial stuff all looks ultimately not to say terminally minimal! 

The one supplied, as expected, looks like it might route exhaust, but as for "silencing", well, pass!

The engine data suggests a "speed rang" (sic) of 1500-9800 and a 15x6 2 blade for 9300.  A LHS with a huge selection of props from many makes did not have a single 15x6 in stock so either they are extremely popular or I'm likely being led a long way out with that info!

The plane has to be capable of prop hang and punch out of that, but speed is NOT important. Noise is!  I have linked the silencer with revs for obvious reasons, but no idea what the lowest EFFECTIVE revs are for the "RCGF 20cc Gas engine w/ CD-Ignition 2.2HP/1.64kw" or how "off" the claims are.

Re: comments elsewhere in another thread on this makes quality good/bad.  Purely by inspection alongside an unused 30cc DLE I have, the RCGF looks just as well made to me. Anyway, its what I have and what I will use, so no further comment is required.

The user formerly know as Bravedan........... Well if Prince can do it....................

itsme

Quote from: fokker on September 08, 2018, 21:30:56 pm
Much the same as Charlie. One pickup and 2 vents usually underneath and behind the engine . Vents made from either commercial fittings or soldering copper or brass tube to a bracket screwed to f1. I join the breathers with an offcut of Tyron  stops the smell and any spillage during transport and storage . If possible put the tank on c of g remember your carb is pumped so no problems with starvation. On a 20cc I'd go for an 18 or 20 oz tank and 3/32 tubing. Keep your vent pipes as high as possible again help stops spillage I will often pass them over the top of the standoff's.
For stopping the engine I use a rcxel opto kill switch or on a mag engine set the trainer switch as engine kill.
Exactly same. Incidentally I aquired a Hangar 9 Taylorcraft with that us style two pipe tank. It's a damn nuisance, syphons fuel out as soon as you take the plug out. It's getting replaced.

Sent from my SM-A300FU using Tapatalk


flynn

Rxcel switches are pretty much standard for ignition kill switches this side of the world. Please use a separate ignition battery - not the Rx battery(ies) the kill switches employ opto-isolators in the rx wires for a reason. ;)  I never saw the need for a second mechanical switch in series but left the ignition battery disconnected after the days flying as the kill switch will have a small quiescent current that will deplete the battery over time.

paulinfrance

I do the same as the others, 'but' I do use the same battery in one of my planes for both the radio and the ignition ( rexel kill switch ) felt clunk on thin tygon tubing and roughed up brass tubing with a spring to hold the tubing on,,

the big problem is the noise, you can try these, they do the job, but I have no idea about the power loss,,
Mode 2 THE only way to fly

itsme

Quote from: paulinfrance on September 09, 2018, 12:01:04 pm
I do the same as the others, 'but' I do use the same battery in one of my planes for both the radio and the ignition
That would worry me to death...I hope its a sub C 6volt.

paulinfrance

It's a 'tamiya' pack minus one element,,,
Mode 2 THE only way to fly

itsme

Quote from: paulinfrance on September 10, 2018, 09:57:52 am
It's a 'tamiya' pack minus one element,,,
Should be man enough then.

Sent from my SM-A300FU using Tapatalk


paulinfrance

It is, and has done around  5+ litres of petrol,,
If you are thinking about separate battery's in your plane, the most important one is for electric retracts,,
I won't tell you why,,  :banghead:
Mode 2 THE only way to fly

Bad Raven

Still stuck on getting flexible enough tubing for inside the tank. Sullivan and Tygon are both too stiff and felt clunk is ineffective at following fuel. (This is a small tank for a 20cc engine, so clunk tube is quite short)
The user formerly know as Bravedan........... Well if Prince can do it....................

Saxon


alangorham

I use black neoprene tube as the clunk line in preference to Tygon in smaller petrol setups.

Some here:

http://www.modelshopleeds.co.uk/catalog/product_info.php?products_id=17450&osCsid=abff6kke9dr1qfcs1f21abr0k6

itsme

Quote from: alangorham on September 26, 2018, 09:48:34 am
I use black neoprene tube as the clunk line in preference to Tygon in smaller petrol setups.

Some here:

http://www.modelshopleeds.co.uk/catalog/product_info.php?products_id=17450&osCsid=abff6kke9dr1qfcs1f21abr0k6
Be careful with that- I had some came with an Evo petrol engine. It broke up inside and filled the carb up with tiny bits of rubber. Obviously not all the same, but....

alangorham

I have been careful with it and have not had a problem. I do add Briggs & Stratton fuel fit to my petrol, but no idea if that helps or not. I'd (naively) hope that fuel tube sold for petrol engines by the engine manufacturer would be suitable for it's intended job though...

itsme

Quote from: alangorham on September 26, 2018, 13:33:41 pm
I have been careful with it and have not had a problem. I do add Briggs & Stratton fuel fit to my petrol, but no idea if that helps or not. I'd (naively) hope that fuel tube sold for petrol engines by the engine manufacturer would be suitable for it's intended job though...
apparently not....took me hours to clean it up.

fokker

Quote from: Bad Raven on September 26, 2018, 07:49:57 am
Still stuck on getting flexible enough tubing for inside the tank. Sullivan and Tygon are both too stiff and felt clunk is ineffective at following fuel. (This is a small tank for a 20cc engine, so clunk tube is quite short)

You ll find once the tubing has become wet it seems to flex a bit better.

The Saint. (Owen)

Why not make a heavier clunk?
Electrickery is the work of the devil.
Proper aeroplanes are powered by engines.

alangorham

September 28, 2018, 11:18:09 am #20 Last Edit: September 28, 2018, 13:00:41 pm by alangorham
In theory that's fine. In practise in a small tank you are limited by the internal dimensions of the tank, plus the size of hole in the tank neck, hence it's easier to use a more flexible bit of tube between the clunk and the pipe in the tank neck.

paulinfrance

Mode 2 THE only way to fly


paulinfrance

I am now getting a bit fed up  :-\ I got my P 47 out and would it start  :-X the yellow tygon tubing
had sprung a really small leak on the carburettor end giving me an air leak, I have tried all sorts of
tubing but can anyone out there give me a good make and adresse for 3mm / 6mm petrol tubing please  :af
yellow, blue or black,,,  :study:
Mode 2 THE only way to fly

itsme

Quote from: paulinfrance on October 06, 2018, 15:59:43 pm
I am now getting a bit fed up  :-\ I got my P 47 out and would it start  :-X the yellow tygon tubing
had sprung a really small leak on the carburettor end giving me an air leak, I have tried all sorts of
tubing but can anyone out there give me a good make and adresse for 3mm / 6mm petrol tubing please  :af
yellow, blue or black,,,  :study:
sorry. Genuine Tygon is the best. There are cheap copies out there...

paulinfrance

How can you tell that's it's genuine Tygone ?, and is it all yellow or does it exist in blue ?.
Mode 2 THE only way to fly

Bad Raven

Quote from: paulinfrance on October 06, 2018, 17:39:32 pm
How can you tell that's it's genuine Tygone ?, and is it all yellow or does it exist in blue ?.


If it doesn't have an "E" on the end of it?   ;D

I have just been handed some petrol tubing from the first generation petrol model engine era, the guy who hoarded it died at least 30 years ago I'm told !!   Just out of interest I'm going to leave it and some modern still stuff in petrol to see how they fare.
The user formerly know as Bravedan........... Well if Prince can do it....................

itsme

Tygon is printed on it. Get it from a reputable trader.

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paulinfrance

I have bought it from at least 1/2 dozen places and none have Tygon written on it,,, :''
Mode 2 THE only way to fly

paulinfrance

No answers anywhere on the French forums ( only a couple ) funny as in the 'Petrol' topics it's
full of posts, but in the end no one seems to actually use or fly them  :banghead:
I will have a go at the Du-Bro stuff, it does costs an arm and a leg  :''but then again you can't take it with you,,  ^-^
Mode 2 THE only way to fly