basmntdweller

My Feedback: (9)

This is a rather basic question but, where do you bring the fuel lines out from the fuse? Drill through the backplate mount or cut hole in top of fuse? Drilling through the backplate mount would be my choice but I want to be sure there isn't a reason not to do so before I get out the drill press.
Thanks,,,basmntdweller

js3

My Feedback: (3)

dweller,

Please do not drill holes through that nice, shiny backplate mount! Sacrilege! What I do, indeed I think what most people do is to have the two fuel lines exit the fuselage on the right side behind the engine cylinder. This assumes that the motor is side mounted.

My theory is that with the fuel lines exiting the fuse behind the engine cyl there is less drag than if you located the lines somewhere else--out the top or bottom of the fuse say, because the engine cyl has already disturbed the air flow. If you have the lines exit somewhere else, they are left "flapping in the breeze" so-to-speak and can cause drag.

I don't know if it really makes a whole hell of a lot of difference because all of the air right behind the prop is very "dirty" anyway but this seems to make sense to me.

Just my opinion. I'm certainly not an aerodynamics expert by any means so I could be wrong. I'm sure people will let me know if I am

basmntdweller

My Feedback: (9)

Good idea John. I'm sure someone else will have other ideas but that does sound better than drilling holes in the mount.
basmntdweller

JohnBuckner

My Feedback: (1)

But what I do for TT engined Quickees particularly wood ones I think two holes out the right side weakens that all to important nose section to much (Preditor flyers particularly) so I exit the feed line drilled through the Jett mount in the upper left just down from the corner and the pressure line goes out the right side an inch or so from the firewall above the area of the pressure nipple far enough that it does not impede on that all important firewall joint. With the TT the feed line is almost a straight line over to the carb nipple. With the Nelson it has to wrap to the underside still pretty clean. I slot the small throttle cable hole to the bottom and by doing all your ships in the same way for either type engine you will have complete commonality. Very handy at a race if for some reason you wanted to switch engines mount forwards for some reason with out going to a backup airplane.

I guess the bottom line is do whatever works for you.

John

Ed Smith

Drilling through the firewall/mount is not a good idea. The pressure line will have to twist and turn back to reach the pressure fitting. There will also have to be some 's' type bends inside the fuselage to get the lines from the tank to the exit holes. All of this tangled mess is a kink waiting to happen.

I use only the bubbleless tanks, Tettra or Jett makes no difference. I install the tanks backwards in the fuselage. The lines exit the tank and in a gentle loop run forward alongside the tank in a straight line. They exit the side of the fuselage through two holes about 1 1/2" back from the firewall. They then run straight to the pressure fitting and the spray bar. No bends, no kinks.

This system works even better with Q40s. With Q40s there is a need for a shutoff. This usually involves another tangle of lines going through the shutoff loop in the engine compartment. I have solved all of that nonsense. My shutoff wire is about three inches long from the servo. The fuel line exits the tank, loops through the shutoff and then heads forward as described. To shutoff the line is pinched into a piece of alum. tube glued to the inside of the fuselage.

With both models, every time I take the wing off I can easily see all of the lines and the shutoff, this makes for easy inspection without have to remove anything.

Ed S

js3

My Feedback: (3)

Hey Ed,

I'm going to give your backward tank idea a try.

How long have you been doing it this way? Is there anything to watch out for?

The idea makes perfect sense, we've just been conditioned to installing tanks the conventional way. But with a bladder, it shouldn't matter!

I wish I could say I thought of it.

Ed Smith

Hi John,

I first did this about three years ago. Before then I messed about with popsicle sticks taped to the tank to prevent line pinching if the tank shifted forward. Now I just sandwich a piece of foam between the back of the tank and the back of the firewall. It does not matter if the tank shifts forward a bit. There is basicly nothing to be careful of. Maybe pay attention to the length of screw coming through the firewall. I do not allow my radio gear to float around and charge into the fuel lines,. Apart from that it is neat accessible for inspection and I wish I had though of it years ago. It does of course work only with bladder tanks.

Ed s

DHG

My Feedback: (7)

OK, Ed, now the $64,000 question. (You may be old enough to remember when that was the name of a famous TV quiz show ... and when $64,000 was the price of a house, not a car.)

Can you lay a "backwards" 6-oz. Jett or Tettra tank on the bottom of the Stinger fuselage (protruding behind and below the wing leading edge) without having the engine starve in a #1 turn due to the centerline of the tank being below the centerline of the crankcase? Bubbleless or not, the effect of G forces should be the same, therefore the tank should not be located below the engine. Right?

You'd think I'd know the answer to this question, but on my Stingers so far I've played it safe and custom-made my own, shorter tank and mounted it as high as possible ahead of the wing. The alternative would be to use a standard-issue tank and chop a piece out of the center section of the wing ... which gives me the willies just thinking about it ... although adding a secondary spar to the wing is still probably less work than custom-building a fuel tank.

Midwings fly better, but you do pay a price in complexity.

Mr. Middleman

Ed Smith

Mr Middleman,

I go back farther than you think. I paid $22,000 for my house, Canadian dollars. That was when the Cdn dollar was at par with the US dollar. Now that really dates me.

The disadvantage of the jett tanks is that they are longer than the Tettra. I use the 5 1/4 tettra tank. Upon reading your post I rushed into the workshop and laid a tank in the Stinger fuselage. With the side mounted motor the tank is not much below the intake centreline. That size Tettra will fit just under the wing LE. When the airplane is on knife edge the tank is below the intake, but so are alll of the other designs. So, I do not forsee a problem. I too do not like to cut into wings at the root. I do think that a notch cut one inch or so back from the leading edge should not create a problem. If that is the difference between the wing folding or not then some attention should be given elswhere.

I have a Stinger primed and ready to finish. I am in good shape with Q40s and bad shape with 428s so the Stinger has been sidelined for a while.

Ed S

IRLJR

My Feedback: (37)

Ed
I've been using Jett tanks, and they come assembled from Mr Jett.
My question is--would it be OK to use some brass tubing to extend the fuel lines, or would this create a potential problem area? I don't think the factory installed lines are long enough for your suggested installation method.
Other than that, sounds like a great idea.
Thanks
IRL

JohnBuckner

My Feedback: (1)

For the life of me Ed, I,ve been setting here trying to figure out how a reverse tank could be a less convoluted feed line route but it just dawned on me your putting the tank forward.

I prefer to mount the tanks centered on the desired CG and have been doing this several years now and of course the advantage is zero cg change during the flight (like I have always said these old thumbs need all the help they can get). The Tettra five and a quarter cap only just barely protrudes into the number one bulkhead and the four oz tank is entirely behind the bulk head. The feed line goes in an almost arrow straight line to a hole in the square mount (yes I do drill the one hole) in the upper left side and runs right along the bottom of the engines top beam mount then the slightest bend to the right to the TT nipple. It is simply not possible to run a cleaner line to the TT. No I do not drill the mount for the pressure line in the square mount , that does go out the right side nose area just above the muffler nipple.

I much prefer to accept a single hole in the mount and one in the nose rather than two in the nose section. No intent Ed to be confrontation by it does indeed work well. I have eight square mounts all set up identically and am embarassed to say have had plenty of firm arrivals but have never damaged a drilled mount.

John

Ed Smith

A brass tubing connector to lengthen the lines is OK.

With the tank on the CG the lines do have a straight run. The tank must be prevented from shifting forward though. The shutoff mess is still an issue with Q40s. I did not have a lot of luck with the tank on the CG I could not seem to find enough room. The tank was jammed up against the wing screw blocks, I did not like that.

While we are on the fuel line subject. The next thing that everybody should be using is the remote needle. Jett sells these for his own and Nelson engines. Bruised knuckles are a thing of the past. I am a born again remote needle guy. Why anybody would still have the needle so close to the meat grinder is beyond me!

Ed S