microengine

On testing my new plane before flight I have a problem with the fuel pick up when the plane is at a climbing angle. I am presently using solid brass pipes inside the tank - the air one is bang in the middle right at the top, the fuel pickup tube is also bang in the middle but right at the bottom. It works at all angles except climbing for some reason. I suspect the fuel level must be away from the fuel pipe at some point.

I have also tried using the usual flex tube with clunk approach. The trouble is the tank is so small (dubro 2oz) that it doesn't have room inside to move everywhere - crap design!!! With this I can climb ok, but not dive on throttle.

What do you think? Is there a better tank design than Dubro 2oz, that actually works at ALL angles? What is clearly required is a spherical tank with a centrepoint pickup, enabling the clunk to move 360 without obstacles. I may have to fabricate one as these muppets have no idea.

Tim Wiltse-RCU

Sounds more like a fuel draw problem rather than a pickup problem. If the pickup is at the rear bottom then it should always be in fuel while nose high. Also it could be that the engine is too lean and when the nose goes up it just leans it out even more and starves it of fuel.

Later,
Tim

skylane42

My Feedback: (53)

I have used the sullivan 2 ounce roound and square with the flex pickup and not had any problems if the motor is adjusted right. Start it up and hold it nose high, the rpms should pick up slightly and you should be able to hold it nose high without sagging or dying. Now, when level you won`t get the last rpm out of the motor and it will drop in rpm. For some reason, alot of people think that you adjust the needle until you have squeezed the last possible rpm out of a motor but then can`t understand why they always have trouble while flying.

Half-A-Hec

I have used many Sullivan 2 Oz. tanks with no problems. Could it be that you have a small hole in your fuel pick up? I have seen this happen before. If you have a small hole in the fuel pick up line, and the fuel level is high therfore covering the hole, then the engine runs fine. Once the fuel level drops exposing the hole to air, then the motor will lean out and quit. Just a thought.


Hec

microengine

I can't find anything smaller than 2oz on the web! Who sells tiny sizes in plastic or metal which are diesel proof?

skylane42

My Feedback: (53)

I`m not positive but the plastic should be diesel proof. It`s the type of fuel line you have to use that is important.

microengine

Just found sullivan make a 1oz round section diesel proof tank, with the right bung.

Anyone ever mounted a tank with the outlets right at the bottom so you don't need pipes or a clunk? Would work at any angle aside from inverted.

Bipe Flyer

The biggest problem I find with the Sullivan and DuBro tanks is that the stopper is so huge that the clunk line starts half way inside the tank. I like the Hayes 2oz. It has a very small stopper with no rubber, the vent is moulded into the tank so there are no brass tubes. The fuel line that comes to attach between the stopper and clunk is black, very flexible and not silicone. A friend of mine uses them for diesel. They are often used on helis as a header tank - at 3 times the regular price.

microengine

Sounds very interesting.

Indeed, the dubro design is appaling for 2oz size. Far too heavy and it plainly doesn't work.

rrragmanliam

My Feedback: (1)

Hello Microengine

Tim Wilst is right on the money. After you set the needle point the nose of the plane straight up and as the engine sags due to the lean out condition give the needle an adjustment to the rich side untill she is a screaming again. This adjustment will also help with the lean out the engine experiences as the tank empties.

As Bipe Flier noted the Hayes tanks are excellent. I don't even use the DuBro or Sullivan tanks anymore. The Hayes tanks are easier to set up and a lot lighter than the other two brands. Also with the smaller tanks use very flexable fule line to the clunk inside the tank. The line that comes with the tanks often times is not flexable enough for the clunk to move around the way it should. Sig makes a excellent 1/2A fuel line that works great for this.

Darren

microengine

I will give the rich setting a go. I think I'll have to order a Hayes from USA, so it'll take a while. Is it safe with diesel?

andrew b

Micro, MFA make a 1oz round bottle tank, it's transparent, the top is screw on of black plastic, type of plastic is PE(polythene), I use mine with diesel, the only thing you will have to change is the fuel line, cost £1.19, comes with all the tube-work, Thats a 2p piece for scaling. I got mine in Leeds If you send me £2.50 I'll post it to you and I'll include the diesel pipe for the clunk!

Bipe Flyer

I don't know if it will speed up shipping or not, but if you're going to order a Hayes tank from North America, Great Hobbies in PEI is closest to you.
http://www.greathobbies.com/products...?prod_id=HAYR2

eroc144

My Feedback: (1)

My only "beef" with the Hayes tanks is that you really have to mount them vertically, and that limits the number of planes I can use them in. I guess you could lay them horizontally, but then the vent sarts blowing out fuel when the tank is 1/2 full.

EG

ClemenTang

Howabout stuffing a small balloon into the tank, connected to muffler pressure, and draw fuel from say the tank's vent line (fuel is filled outside the balloon).

Clement

mylamo

My Feedback: (1)

My small diesels use the one oz.shampoo bottles from
hotels. Drill 7/32 holes and cut your black tubing at an
angle to get it started,then pull it thru with pliers. You
may use a clunk if you feel it is needed. Then screw the
lid on,it becomes the rear of the tank.
Ralph

microengine

Great tips all round and very much appreciated. I have a few tanks ordered now, so I'll get experimenting shortly. Thanks Guys!

Andrew, you have pm

microengine

You guys were dead right. I adjusted the carb to a richer setting and it works much better. However I noticed that if it was rich enough to enable perfect running on a verticle ascent, then it's too rich when in a dive under tickover throttle, as the engine struggles and dies. I had to reach a compromise setting which allows near vertical ascent under all throttle settings plus a vertical dive angle under partial throttle to max throttle. As long as I remember to have the engine above idle on a vert dive it will now be fine.

However all the above testing was done with the fuel tank out of the plane, to eliminate the pickup issue's at extreme angles. The engine is now perfect, but I still need a better designed tank. I have in the post a sullivan 1oz round bottle and slant bottle to get me going for now, plus a 2oz Hayes from USA (which will take a while), plus hopefully Andrews MFA 1oz tank shortly.

Looks like I might even get airbourne at this rate! Thanks all

Tim Wiltse-RCU

micro,

You know you can build a tank from a Fuji Film canister right? Takes about 10 minutes to make one yourself. It's about 1oz. Do a search on this forum for the drawings.

Later,
Tim

ClemenTang

What's the engine? Guess it's not a twin needle?

Clement

microengine

PB 033 diesel:

http://www.peterburford.com.au/

ClemenTang

well you probably can't do any better with an air bleed carb. But consider this, while you can dive or descend at low throttle and a steady speed, maintaining a nose down attitude for a period of time, the plane can never hang on an idling engine in the air. This means in a nose high attitude the fuel is either weightless since the plane is deccelerating or unless otherwise you're at high or full throttle. Think of a stall turn.

Clement

microengine

Now your getting technical. I'll be happy to just keep away from the green stuff below

andrew b

I posted the tank this morning, should be with you on Monday

microengine

Great, thanks Andrew!

The 1oz slant sullivan arrived today. It's a sensible size but it has the same problems as the dubro - the clunk won't move everywhere inside as the clunk is large, the tank is small.