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All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> fuel shutoffs
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fuel shutoffs - 1/7/2003 9:09:29 AM   
daven



Posts: 7012
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		I think these simple clamps are the way to go. They are cheap and fool proof. They stay on the line, so you can't loose them. They are also the best value of the bunch. The clamps come in assorted sizes in the same package. You can use most of them, but some are for larger fuel tubing. The smaller ones can be drilled out.

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those litttle things.... - 1/7/2003 8:17:14 PM   
splatt



Posts: 651
Joined: 1/30/2002
From: splattsville, MN,
Status: offline 		Last year was my first running those little clamps with my tetra tank. I had very good luck with them. I found them on the RC car side of my LHS. For a couple bucks there a good investment. They slide over the line and do a very good job of pinching the line shut without having a hemostat swinging around. For the price I plan to change them in the spring

For my routine on the start line after the clock starts I put on the glo, click the fuel clip, and start spinning the motor. Worked sweet. Now I just need to have a winning season

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       Post #: 27

Picture of the tank - 1/8/2003 12:48:31 AM   
Per_N



Posts: 207
Joined: 9/4/2002
From: Stockholm, SWEDEN
Status: offline 		Bill, i appreciate the time you took the wright this novel down. I really helps me understand. You talk about syringe, I don't know what that is but I can imagine that there is a giant one of (like this they have on hospital's, but without needle) Am I right?

The clamping technic is a little scaring, I don't want any problem to start the engine at the start point. The adrenalin is really high without this little incidents. But I can imagine that there is something you will learn.

I post a picture of the box for my tank.

Thus someone have any picture how to implement the engine shutoff.
I have read Dub Jett's instruction, but i think that is a little overkill.

Thank's

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Per
Sweden

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Tetra Picture - 1/8/2003 1:02:35 AM   
daven



Posts: 7012
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		per_n,

In your picture of the tetra tank, it shows an awful lot of tubing coming out of, and into your tank.

You only need two lines. One for Fuel, and one for pressure. The pressure line is easy, because the nipple is already there on the bottom side of the tank. The fuel line is notated as line "B" in your picture and extends approximately half way into the tank. You do not need a clunk, the backpressure will squeeze the bladder forcing the fuel out the fuel line.

Here is a picture of the Jett syringe. I'm guessing it holds 10-12 oz of fuel. You fill the syringe about 1/2 way up of fuel by pulling the plunger out the back. Point the hose up, and push out any additional air in the syringe. Attach the syringe to your fill line, and suck the air out of your tank. You should get all the air out before the plunger comes out the back of the syringe. Once all the air is out, push the plunger in, and fill the tank with raw fuel only (no air). You can tell the tank is full when you get a little pressure while pushing. Be carefull when you push, the bags inside the tanks can break. Suck a little fuel back out, and clamp off the line, and hook up the line to your engine.

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Dave Norman

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Daven - 1/8/2003 1:47:55 AM   
Per_N



Posts: 207
Joined: 9/4/2002
From: Stockholm, SWEDEN
Status: offline 		Ok Daven!
So i will not using the other ones. My guess about a syringe was right then.
Do you use engine shut off by clamping the fuel line or do you use throttle?


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Per
Sweden

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Daven - 1/8/2003 2:04:10 AM   
Per_N



Posts: 207
Joined: 9/4/2002
From: Stockholm, SWEDEN
Status: offline 		The first picture of the fuel shutoff, the one that looks to be in aluminum. Are they for use together with a servo for engine cut off?

I'm looking for a easy way to build a engine cut off.


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Per
Sweden

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Fuel Shutoff - 1/8/2003 2:26:15 AM   
daven



Posts: 7012
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		Per_N.

I do not use a fuel cut off for Quickee 500. The Nelson Q500 has a barrel carb that you can close. On Quarter 40 however, the Nelson has a simple Venturi, and you need to use a cut off.

On the quarter 40s, this is how I do it. I take a Bic pen (I attached a picture in case you don't know what that is). Remove all the pen stuff from inside the outer tube of the pen. Cut about 1 Inch off the length of the outer tube, this is all that you will need. Measure the outside diameter of the tube and cut a similar sized hole in the corner of your firewall (If you are using a full backplate mount like the nelson, this may not work Unless you cut the hole through the backplate also).

Glue the 1 Inch section of tube into the firewall. Make sure that the plastic tube is sanded smooth on the edges, so there is nothing rough that could wear or cut your fuel line.

I then take a length of relatively thin music wire, and make a loop on one end that is just big enough for your fuel tubing to fit through. I like to solder the joint of the loop so it does not come apart. Push the non looped portion of the wire through the plastic tube, and run it along the edge of the fuse to a servo with a EZ connector. You take the fuel line that runs to your carb and insert it through the loop of your shutoff. Adjust the servo so that when activated it will pull the fuel line into the tube. The fuel line will fold over and shut off supply to the engine.

A couple of things to consider: Use as soft as fuel line as you can find. Some of the harder lines don't pinch off all that well. Make your fuel line a little longer than you normally would to compensate for what will be pulled into the shutoff. You need to open the throttle back up after you land and shut of the plane, if you leave the fuel line pinched off, you will not be able to refuel.

I'd post a picture of the shutoff, but as you can tell, I'm hard at work and the plane is at home.

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Dave Norman

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Daven - 1/8/2003 2:40:49 AM   
Per_N



Posts: 207
Joined: 9/4/2002
From: Stockholm, SWEDEN
Status: offline 		Ha ha I now what a pen is. This is about the same that Dub describe on his website. I have not decide yet if I should mount the tank backwards or not, but the technic will be the same anyway.
In our class of 428 we don't have to use a carburetor, so i have order my Nelson with a venturi from the FAI engine. More power = More speed. Hehehhe
It will probably show up in my mailbox any day now, can't wait...... to see the beauty.

Thank's Daven, and sorry to badder you at work. I'm leaving for bed now.


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Per
Sweden

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Goof'n off - 1/8/2003 4:51:53 AM   
Bill Vargas



Posts: 1571
Joined: 1/6/2002
From: Team Coldies, CA, USA
Status: offline 		>>> I'd post a picture of the shutoff, but as you can tell, I'm hard at work and the plane is at home.<<<


Dave, are you Goof'n off again?


BV

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fuel shutoff - 1/8/2003 7:37:59 AM   
daven



Posts: 7012
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		per_N,

the first picture of the hemostat (Metal clamp) is used after you fill your tank with fuel, to keep the pressure from pushing fuel into, and flooding your engine.

You take them off just before you want to start the engine. You will need a seperate control to shut off the plane.

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Dave Norman

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supertrc.com

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       Post #: 35

Servo installation - 1/12/2003 1:47:15 PM   
Per_N



Posts: 207
Joined: 9/4/2002
From: Stockholm, SWEDEN
Status: offline 		Bill
On your Woodie you have not installed the servos under wing, Is this only for getting the CG right or is there another reason?


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Per
Sweden

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       Post #: 36

Servo Location - 1/13/2003 9:43:56 PM   
Bill Vargas



Posts: 1571
Joined: 1/6/2002
From: Team Coldies, CA, USA
Status: offline 		Per_N, Having the servos back behind the wing does 2 things for me,,, it allows for more room in the wing saddle area of the fuselage to bring the tank back close to or on the CG and clearance for the aileron servo.

CG is acheived, for me, by shifting the battery around within the fuselage to obtain a correct balancing point for my Racers



BV

_____________________________

If it ain't leaking oil, then something's wrong,,, USMC, RETIRED!

(in reply to Per_N)
       Post #: 37

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