NewFlyingMan

My Feedback: (24)

Is there a maximum distance and/or a specific orientation an exhaustpressurized fuel tank should be from a 2-stroke engine, without using aseperatepump?

Thanks

Jetdesign

My Feedback: (8)

Centerline of tank as close as possible to level of spray bar in carburetor.

Tank should be very close to the firewall.

I just tried running an engine with the tank set back from the firewall a few inches and on longer verticals it went lean. The muffler line is still open to atmosphere at end of muffler so the pressure is not great, and the engine does not suck fuel with much force.

If you just want to move the tank a few inches, best thing to do is move it in small increments, fire up the engine, hold the plane vertical and see what happens. That will give you a rough idea, of course G-forces will come into play in the air and make it harder at times for engine to get fuel. I think you get the idea.

I have tried just about everything, short of a header tank which people tell me will not work, to move tank away from firewall.

It is next to impossible to come up with a definitive distance figure for tank from engine as there are way too many factors to calculate it.

If you want the tank at the CG, use a YS engine, next option is a Cline Regulator or a Perry Pump.

NewFlyingMan

My Feedback: (24)

Thanks for the info Joe.

I'm playing around with some pusher prop ideas and want to get the tank to the CG. I read up on the Perry and Cline pumps here on RCU and think I will go one of those ways. They cost just a little less than a new or used YS.

Keith

jay2000dakota

I have a 60 size Goldberg extra300s with aSaito 150s. In short I wanted a 24 oz tank andit wouldn't fit so I ran a 6 oz header tank in the nosewith a 18oz main tank placed on the cg. It works perfect other then you need a filler/drainer for each tank (3 line setup), Iknow that a 2 strokedoesn't draw fuel as well as the 4 strokeso a pump my beneeded between theheader and main tankbutwith the header tank youcan mount the main tank almost anywere.

Gray Beard

My Feedback: (-1)

Odd this question came up tonight, I was fighting this problem all day today at the field. Ijust built a plane and had no room for the tank anyplace close to the engine. Some engines draw fuel better then others so Iwent ahead and installed my tank so the bung is 8 inches away from the carb.
Runs great until the tank is drawn down to right at the 1/4 down mark then the engine would go lean on me and start pooping outdoing anything with a high G. Just not enough pressure.
Iwent ahead and tried to get it into tune at that level without any luck at all, it's just too far away. Ihave a friend with a Perry pump that I'm going to borrow and try to see if that will cure my problem, Perry makes a couple of different types but I have never had to use one for my own planes so Ihaven't a clue how well it/they work.
Imay know more next week if these storms will quit blowing through.

NewFlyingMan

My Feedback: (24)

Gray,

Search the forums for info on the Cline and Perry pumps. The posts may give you some more ideas about the best solution for your issue.

andrew66

A pump would be the best way to go, but you could try using the uniflow setup (muffler pressure goes on a clunk) and a third line to vent when filling the tank.  The tank on my kadet is fairly low and is about 4 inches away from the engine, and it runs fine.  I have a webra 40 in it.  That would be a cheaper way to try before buying a pump.  I actually use this system in all my planes, cause i find that the fuel flow is more consistant and the engine doesnt go lean for the last part of the tank.

JohnBuckner

My Feedback: (1)

Often a bubbleless type tank from Tetra or Jett that uses no clunk at all will solve some of the problems of a remote tank without resorting to any pump. They are normally mounted on the CG and require no foam.

The are virtually universal in most pylon and combat events and while they won,t pressure up like a pump the are superior in fuel delivery to a conventional tank and can be mounted a considerable distance.

So just how far does the tank need to be away from the engine firewallin this pusher. Another factor to consider is the fact that in a pusher the tank clunk type tank needs to face forward even though the engine is behind it. With a bubbless there is no need at all to face the tank forward in the direction of flight to allow the clunk to work properly because there is no clunk and the only outlet in the tank is in the middle and the bladder brings the fuel to the outlet. Doesnot matter what directionand this could save considerable distane the fuel has to travel in the pusher.

John

jaka

Hi!
Yes!
A Tettra "Bubblelesstank" can be placed more reward than a ordinary R/C tank without problems.
These tanks are used mandatory by all pylonracers all over the world!

Gray Beard

My Feedback: (-1)

Idid give the Tetra tank some thought yesterday, Ihave several thoughts about my little problem. A one way valve?? The Tetra?? And the pump. Maybe a combo of all of them?? This is the first tank Ihave had to mount this far away without a pumped engine. Ihave used the Tetras for racing but they are a bit of a pain for a sport plane. I know, I'm a lazy old man!!!

vertical grimmace

My Feedback: (1)

No need for a one way on a bubbless tank. I would say to start with the tank and see how that works then go from there. Do not make several changes at once, just one.