Calvinman

Hi,

I recently replaced my FX 46 that I sold years ago with a AX 46, with the remote needle valve there is not a lot of room to install a fuel filter, I manged to cut down one of those filters with the clear hose and two pieces of screen in the line. I was wondering what others have done, maybe someone has a better solution.

Calvi

JohnBuckner

My Feedback: (1)

Its very simple: I do not use filters but if you prefer look at these first three pictures and how the simple two line fuel system is fueled with a rear needle engine This method involes just putting a cut in the tank feed line where it is accessable and using a short piece of tube here. This is the place for fueling and defueling, now if you want to use a filter you mearly substitute that short tube with the filter.

If a cowl is used simple two little holes later and your done, it will look like the last photo.

John

RCKen

My Feedback: (9)

Like John I don't use a filter on my plane. Rather, I have it on the fill line for my fuel jug so that the fuel is filtered when it's pumped into the tank on the plane. IMHO having a filter on the plane is just one more thing to have go wrong, I've always subscribed to the KISS mentality (Keep It Simple Stupid)!!!!

kwblake

+1

CGRetired

My Feedback: (1)

+2. I started using a filter but it got in the way more than it was useful. I filter my fuel before pumping it in the tank and have never had a problem with fuel contamination.

Watch.. now, next time out, I'll get into a problem with dirty fuel... ha.. oops.. sorry. Murphy's law!!!

CGr.

Calvinman

Thanks for your replies, I too like the "kiss" principle(sp) but am not quick to change, on my old engines I would use the filter as a place to "splice" the line for filling and after a flight to seal the tank by connecting the fuel line with the filter on it to the vent line. That is some super sweeet cowl on (I'm guessing) that Sukoi John.Any way as you can see by the photo I have a working filter for now. I am going to put the motor in my Ultra Sport once I get it built and will use a three line system as outlined in another thread.

Calvi.

Gray Beard

My Feedback: (-1)

I have a filter like John shows on the inside of my fuel can pick up line and then a crap trap on the fuel can fill line. Never have had a problem with dirt. On a couple of engines/planes I do use an in-line crap trap but just because, no real reason. I have learned to always put in some fuel in a new tank then shake and drain before I assemble them to clean out any of the plastic from the molding process, loose flashing can be a problem with a new tank.

fredscz

My Feedback: (47)

I always use a filter in the line on the fuel can and between the engine and the fuel tank in the plane. Normally I use it as a place to break the line to refuel the plane. I also use heat shrink on the take apart filters so they will not come apart and I have a better grip on it. New fuel tanks are not clean and need a lot of flushing before they are clean enough to be used so I just go with a filter to start with.

Hossfly

I like fuel filters. If one just happens to use "bladder tanks" where the fuel is inside the tank bladder and the pressure is outside the bladder, one will most likely marvel at the amount of goop that gets into the tank from that muffler pressure source. They do require some cleaning out every so often.
Without bladder tanks, the filter in the feed line earns its pay keeping that goop out of the carb.

To me bladder tanks, especially for larger glow engines, are well worth the price. Those with 3 line set-up are really best for most flying. The two line tanks are definitely
the choice for Racing however too much trouble for me on a sport airplane. I use both but I'm not much on the racing anymore. []

Filtered fuel is certainly worth the trouble and I do same. Flying off grass fields mostly gets a lot of garbage through the carb the engine and out the muffler. Finally it can make that carb spray bar give one some pain!

Calvinman

Hi Hossfly,

That is the second time I have heard about the junk comming from the exhaust, I think I may have to try a bladder tank, what sizes are they available in and where can one obtain one. I also run a flilter on my fill line, I do not like to pump out my tank after I fly, I just "seal the tank" by attaching the vent line to the fuel line.

I have even read in a thread some where you can put a filter in the pressure line between the muffler and the tank.

Calvi

JohnBuckner

My Feedback: (1)

Calvi you are serious danger of overthinking this fuel instalation business and especially the filter thing! I would never suggest putting a filter between the tank and muffler all that will do is rapidly reduce the head pressure in a very short time and next thing you know you are back on here trying to second guess whats wrong and why your engine is so cranky.

Filters are easily plugged and with so many you will be having all sorts of fits most every time you go out. Now the gunk that gets through the muffler pressure line is almost all unburnt oil that is the by products of cooling the engine. Only a very small percentage of that is combustion by products that is harmless to pass into the engine agine However all that unburnt cooling oil will indeed be beneficial to the engine to allow it to repass.

I use no filters at all in our desert environment and almost all is off desert hardpan earth and I have no problems with my hugh variety of engines and I fly everyday (well am slowing a bit after a major operation but still up to four days a week) . This when compared to new folks who show up and overthink the filter things (they usually end up with far more problems than me).

OK lets talk about the "bladder tanks" that have been brought up. Its not clear if bubbless tank is what he means or bladder pressure types. Two very different animals. I suspect what is meant is the Bubbless type tanks and these are marketed only in this country by Central Hobbies and Jett Engineering. The Jett tanks are only go up to 6 ounce and intended for high performane engines. Tetra Japanese tanks are what is sold by Central and both of these types are alway refered to as bubbless tanks. They do not pressurize the fuel supply over what any muffler pressure system does but they do have superior fuel delivery perfromance over conventional muffler pressure systems.


However they are very expensive and Starting out at around 23 bucks and they require some special fueling considerations which nomally requires a special high capacity fueling syringe (about 35 bucks) and it takes much longer between flight to prepare the tank.
For a bubbless to perform its best the air must be drawn out of the bladder completely before fuel is pushed in. This is almost impossible to do with a any ordinary pump even with a third lines so the advantages of the bubbless is lost that way when air is introduced into the bladder.


Its a waste of time and money, my advice is to loose all the filters except the one on your fuel can pickup hose just like Grey Beard mentioned and simplify your fuel system with a new (five bucks) Hayes (o) ring type two line fuel tank and use a simple split like I have illustrated many times for fueling and you have far better utility and reliabilty of your power system


Bubbless tanks are superb for certain extreme (G) high performance types and some problamatical airplanes. For your use a bubbless is completely unneeded and impractical.


Here is a link to the Central hobbies page with the Tetra bubbless tanks. Becareful they also have tetra tanks that are conventional although superb tanks those cheaper ones are not "Bubbless".

http://www.centralhobbies.com/Fuel/fueltnk2.html

here some of mine and also shows the Jett "tanker" syringe usually used:

John

rlipsett

I have used fuel filters for years on my ys engines. they are sensitive to dirt and to ensure trouble free operation they need filtered fuel. the filter I use is not a great filter but it is small and it provides that extra bit of filtering to keep the engine working without troubles. http://www3.towerhobbies.com/cgi-bin...?&I=LXBNU8&P=7

opjose

Hmmm...

On my planes I filter the fuel as I fill, with a filter on my pump.

I also have a bubble-less brass clunk filter in the tank.... and on larger planes another filter between the tank and the carb.

As long as the connections are tight and clamped ( I use plastic wire ties everywhere, and no glow and gas does not dissolve them... ), there are no "complexity" issues, nor junk getting to the engines.

On my gassers the effects of these multiple filters really is noticible. After several seasons of flying the carburator screens are perfectly clean.

With only one filter in the plane, the screens do not have debris but they DO get a film like amount of smaller particulates that imped fuel flow.
Most people have to periodically clean the carb screens. I don't.

Calvinman

I'm no stranger to danger John,

I did not mean I was going to put a filter in the pressure line, I'm with you on that one, would gum up seriously fast. I kind of like the idea of the bladder tank, but as you stated probably not neccesary.

Rlipsett, I don't think that filter would fit, with the remote needle there is just no room unless I corkscrew the fuel line I may be able to use the filter in place of the crap trap I had to butcher to fit between the needle valve and carb though, I don't want to use a metal one there as it will rub on the cylinder. The filter in my filler line and the craprtap between the needle valve and the carb will have to do the trick.

Opjose I still like to use a second filter(one on my filling station, one on the aircraft) it has been my experience that the second filter will indeed trap some particles, but it is not a neccesity, just a matter of personal preferance.

Calvi

Hossfly

John, FYI Tetra has a 3 hole bladder tank that does NOT require a syringe. Bladder, bubbless, is to me all same. Fuel is in the bladder without bubbles if filled correctly.
I have a dubbjet big syringe but seldom use it as the smaller ones do OK. The 3 hole is almost same as a regular tank. I fill with my pump until it overflows, then close the overflow outlet. Runs are very steady. I don't use them on all airplanes but some I do. It is just another option.
As far as costs are concerned, that is up to the user whether he/she wishes to pay the price. NOT my business as I am no one's financial advisor. Therefore I am free to advise on what is available. Like many ask me why I don't do 2.4 more. Actually I like the antenna sticking out there.
I have 4 2.4 systems. I fly every so often but 72 mhz is MY choice. Now if a guy wants to use the available tanks for better , then that is HIS choice. They have worked well for over 50 years.

JohnBuckner

My Feedback: (1)

My response was intended only for Glow engines operating on conventional muffler pressure fuel systems such as the OP's .46AX, Not closed circuit two line pressurized systems such as the lovely YS engines and not gassors with pumped pressure carbs. Those are an entirely different matter and only serve to cloud the matter.

I use no filters anywhere except the fuel cans pickup hose.

A bubbless tank is pointless unless there is are specific conditions or needs. And yes Horace FYI all tetra bubbless tanks come with a second hole in the plug to be punched out for three line use if one chooses.

The answer to the original question is of course cut the carb line where needed and install a short tube or filter (your choice) which becomes a fueling point when using two lines better and more reliable.


John

jester_s1

Calvinman, I see an issue with what you did there. Your needle valve isn't getting filtered fuel, and it is a place where dirt tends to cause problems. I had an install similar to yours recently, and I put the crap trap filter inside the tank between the clunk and stopper. It added enough stiffness to keep the line from sliding forward (I normally put a piece of brass tube in the line for that) and it keeps me from having that bulky filter in such a tight space going to the needle valve. I use a 3rd line for fueling.

opjose

Yup... those "crap trap" filters do the job don't they.

They certainly are simple, but I like the ease of seeing any particles or gunk that might foul things up.

CGRetired

My Feedback: (1)

What would we do without the expertise offered by such "pro's" as John, Jose, and Horrace. And, I thank them for that.

But, I really think, that since this is a Beginners forum, most folks that are posting here, that are looking for advice, are Beginners. Should we get into pressurized four strokes with futuristic fuel system?

After all the time I have had with RC, I fly with a simple muffler pressure system and it works just fine.

Some of the points offered here are great. For instance, I will look closely at the clunk that I use to make sure, after sevreal seasons of use, that it is not clogged. I use this clunk:

http://www3.towerhobbies.com/cgi-bin...?&I=LXXF25&P=7

It is not advertised as a filter clunk, but it behaves as one, well sort of. It offers plenty of advantages over the normal clunk. So, I keep them around. Now what I learned here is that it might get clogged and may require me to look at them and maybe replace them to prevent clogging. But, that's pretty much it.

If you are a beginner, don't get to wrapped around the axle about fuel tanks. A simple muffler pressurized system with two lines, a muffler pressure line and a fuel supply line - one that goes from the tank to the engine fuel supply, will work just fine.

CGr

Calvinman

Thanks Jester will do.

Yes CG that clunk has been on my wish list for a while.

Calvi

rlipsett

calvin with the filter I showed you in my earlier post the size is extremely small. With the the center section that has the filter in it is less then 1/4 inch long. the whole filter from barb end to barb end is just over 1/2 inch and a little less then 3/4 of an inch.

opjose

I find that these are a bit better as the holes are much smaller...

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXD741&P=ML]Dubro Filter Clunk[/link]

jester_s1

Those Dubros aren't as heavy as a standard clunk is though, so sometimes they require extra weight to be added. I've hammered out a piece of lead really thin then wrapped it around the fuel tubing before to get it to flop around right. The only caveat to using those is that if you have anything in the fuel coming in, it's going to all bunch up in the line before the clunk and come out all at once to your carb. Filtering your fuel from the can AND keeping the filler fitting clean will prevent that, but I run a 3 line system on tanks that I set up with a filter clunk.