chuck993

Hey Wulf, I'm glad LADO has worked out for you...

chuck993

I already have issues trying to get the servo and retracts working well, I used the recommended retract servo and the thing rotates too much, even with trying to reduce movement thru the computer...I'll get it...

mrsand

I have a fuel system question.

I have mounted a Saito 100 with the valve covers down and left at +- 45 degrees.
What tank/fuel line setup is recommended...one person says a three line...others a two line setup. I have a dubro fuel valve I was considering using.
I appreciate any help I can get. Thanks.

MrSand

bignasdy

I use a three line system on all my planes....never had any luck with fuel valves personaly.

bignasdy

move the rods inbound on the servo arm or wheel. They should be no more than an inch apart as I remember...

da Rock

Fuel valves in the model take some learning to be reliable. They fail often enough that you'll meet more people who no longer use them than newbies asking if they're ok to use.

The number of lines means a lot less than getting the TANK LOCATED RELATIVE TO THE CARBURETOR.

BTW, there are two different ways to plumb a three line. Uniflow is one and often gives a smoother engine run. Some three lines work just like two lines.

I just went into my H9 P47 to move the tank. It's had a couple of different 3-line setups. The tank location problem defeated both. I should have looked harder at where the tank winds up in that huge fuselage.

bignasdy

I know guys that have no probs with fuel fillers, so you be the juge....try it out if ya want....in my experience, they hve leaked into my airplanes, and allowed air into the mix....I tried several different brands....all back in the 80s so they may be better now....try it out and see what ya like.

mrsand

ok thanks,

I'm sure you fellows know more than me.... The tank is a little higher than the carb since I inverted the saito. If I keep it to two lines how do I keep the system from flooding when I fill. Sorry for my ignorance

MrSand

Cherokee Flyer

I am using a three line and have the same Saito you do mounted the same way. The three line I use has two clunks, or you could use either line to provide fuel. I fly with a DX-7 and close the throttle completely when I shut the engine down and never have a problem with it flooding. I always roll the engine through a couple of compressions or backward if needed by hand before trying to start it. If it is loaded, it will clear right out.

Using the three line like that allows me to get all the fuel out fo the tank at the end of the day.

L.

bignasdy

why you got two clunks?

chuck993

I usually use a three line system for my nitros, with 2 clunks and a fuel dot for filling, no tees.

bignasdy

again, why two clunks...makes no sense to me......

Wulf

My Feedback: (5)

I use 2 clunks (3 line system)in one of my planes, my thought being for filling and to drain fuel out of tank completely when done flying-The plane flies without any problems and both clunks move in tank as one.The plane is a 1/4 scale Sig Clipped Cub.Just something I tried and it works.

Ron

skorman

My Feedback: (3)

I also have a 3 line system with 2 clunks in my Hellcat. The third line goes to a Hangar 9 fuel dot. The easiest and most reliable system IMHO.

da Rock

You use two lines in the fuel with Uniflow. And you can use two lines in the fuel if you want the 2nd line for emptying if the plumbing isn't Uniflow.

You want the tubing those clunks are on to follow the fuel during maneuvering (a necessity in Uniflow plumbed tanks) or you want the line that's just serving as a fill/empty line to be on the bottom of the tank when the line is used to empty the tank.

A two line plumbing layout won't need two clunks. There won't be two lines in the fuel.

Three line layouts can be Uniflow or not. When they're not, the extra line immersed in the fuel is a fill/empty and will need to be at the bottom of the tank when you're defueling.

chuck993

Da Rock explains it above...I use a 3 line system, one for filling and de-fueling, that line goes to the cowl and is connected to a fuel dot. This is an easy way to fuel and de-fuel, the other lines are the regular lines. I have a clunk on my fill line and one on the carb, the other line is the vent line, so 1 carb line, 1 vent line and 1 fill line...works like a champ!

mrsand

Just wanted to confirm or get other opinions on using Futaba 3004 ball bearing servos for the for the H-9 60 Class Hellcat
Thanks for your comments.

Mr.Sand

bignasdy

well DA, still makes no sense to me personaly......I dont need a clunk to fill a tank, or vent it....anyhow, whatever works for You, is all good with Me!
d

da Rock

The clunks are at the pickup end of the lines. They're there to weight down that end of the tubing so it'll stay under the fuel through maneuvers. They keep the pickup laying on the bottom of the tank when you defuel. Fuel tubing by itself has no reason to lay on the bottom of the tank nor follow g-forces in flight.

bignasdy

LMAO...I know man...Ive been doin this since the 60s....I was refering to "Multiple clunks"...

da Rock

OK, "multiple clunks" are used with Uniflow. Uniflows have three lines into the tank. Two go to the back of the tank and the desire is to keep them both under whatever fuel is in the tank. You can either have one clunk on the pickup and tie the pressure line to the pickup line, or put a clunk on each and not tie them together. Leaving both free permits both lines to remain as flexible as possible. Tieing them together often makes the combination stiff.

And multiple clunks are used everyday in tanks that have two lines down into the fuel when one of those is used to fill and drain. The drain line won't work worth spit unless it's pickup end is at the bottom of the tank when you're draining the fuel. A clunk insures it's bottomed out. And of course the fuel line to the carb would have a clunk.

I usually install a tank setup for Uniflow. They sometimes have a problem with siphoning. If that tank siphons and rerouting the hoses in the engine compartment can't cure it, it's an easy job to change those engine compartment hoses around so the tank no longer works as Uniflow. It works like a regular two line tank, but with a third that's only used to fill and drain and is plugged when filled.

Hope this helps your understanding.

chuck993

Mr Sand, I would think they are fine for use in the Hellcat.

bignasdy

thank ya DA... its always nice to see different things that work. I personaly have always used a three line system....one with a clunk to the carb, one vent tube to the top of the tank, and a stright tube that just sticks in far enough to fuel up. When I drain a tank, I simply detatch the line from the carb, and suck it out with the fuel pump.....but usualy, Im about empty when I land so I just run the engine a few minutes to drain the tank, and the crankcase dry. As far as uniflo, dont know what it is exactly, but your explanation is a good one, and I appreciate ya taking the time!
thanx
d

da Rock

Glad the typing went to good use.

Truth is, your setup is almost mine. Your fill tube...... stick a line with clunk on it and you'll never need to drain from the carb line. It'll fill just like before because filling can be from anywhere in the tank. And it'll drain as good as the pickup line does, but you won't have to unhook that from the carb.

RBean

After I lost the Hellcat this spring when a wing came off I've got Hellcat II up and running. RCGF 20cc gasser and Century Jet Air retracts and 4" Robart tires. (all left over from the crash). This time I reinforced the wing in the wheel well area and the horizonal stablizer. A little heavy at 11.5 lbs. but flys nice with that big wing, even at this weight. The gasser is turning a Master Airscrew 3 blade 16-8 at 7,800 rpm. Plenty of power. I now pull the power back when heading down hill. About 20 flights on her now and doing good.