DaveCFI

Hi all,
Been working on my 4-Star Forty kit like crazy the past few days. I got a new engine for Christmas...kinda lit a fire under me to get 'er goin'!
Anyway, I have the fuselage glued up and am wanting to get the fuel tank situated before I seal that area of the fuselage up with sheeting. This is my first kit build too, by the way. I have a Super Tigre 45 engine and a Dubro 10 oz. fuel tank. Also I used a Hangar9 universal engine mount instead of the mount provided with the kit. My thrust line is right where they say it should be in the directions. The instructions say that ideally the centerline of the fuel tank should be inline with the needle valve on the engine but it should not be more than 1/2 inch below. My centerline is 1 1/16" below the needle valve. However the lines that go out of the fuel tank are at the top of the tank and they sit less than 1/2 inch below the needle valve. Will this work? I don't know what to do if it doesn't because I can't raise the tank up any higher.
Also, I am trying to plan ahead and not paint myself in a corner...I fashioned a lite-ply bracket that secures the tank in the comartment. I am afraid that it may get in the way of my throttle push-rod when it is time to install that. Check out my pictures and tell me what you guys think. If it is ok, then I'll glue it all up and get moving onward.

Thank you!
DaveCFI

DavidAgar

My Feedback: (108)

You need to get the fuel pickup tube from the tank as even with the fuel intake on your carberator. If you get it to high it will have a syphon effect and to low will make for a constant tuning of the needle valve. With a 10 oz tank I am hoping that you have room under the tank for the battery as all my 4 Stars have the battery up against the firewall for balance purposes. Under no circimstances glue in you tank bracket befor you get you throttle controls installed. Good Luck, Dave

DaveCFI

If I put a smaller tank in this plane the fuel pickup would be even lower.
C'mon guys, there are tons of you out there who have built this plane...what did you guys do? I might be able to raise the tank 1/4 - 3/8 of an inch but the tank would then be right up against the top when the sheeting is installed.
Also, the battery will need to go clear up by the firewall to make this plane balance??? I don't know where it is going to go. I really could use some more input to help me not screw up in this critical phase of building.

Thanks again!
DaveCFI

k3 valley flyer

My Feedback: (18)

That will work. Hayes tanks are a better option.

carrellh

The padding on top of the tank probably should be touching the top sheeting. I'm still pretty much a beginner, but my experience has been that a slightly low tank is not a problem.

jaka

Hi!
When I see your first picture I ask myself - Why doesn't he mount the engine on it's side?? That way you will have the tank and engine in perfect alinement!

It's never good to mount the tank soo low as you have done...it will always mean trouble in the long run..
As said before the tank should be mounted so that the center of the tank lies inline with the carb intake orifice when the airplane sits horizontal. That's an old rule you never should forget if you want your engine and plane combo to function properly.
How you mount the fuel lines doesn't improve things, you can have the tank low or high...with fuel lines going above the tank or under...this will not improve the running of the engine !

All you have to do to have a proper set up is is cut away the side plate and turn your engine mount 45 degrees...!

jrbmoto

I know what your saying..I also questioned the tank placement on my first 4*, but after a flight or two, it was clear that it doesn't seem to be a problem. I've built several 4*s over the years and never had a fuel draw problem! Go figure! I've always been able to run the tank dry!
-Johnny-

buzzard bait

After adjusting the engine to run properly upright, it is likely to be rich when flying inverted because now the tank is high instead of low. It's not necessarily a big deal, depending on how rich it gets, though it might be for some people. For brief periods of inverted flight you might not notice.

By the way, I wouldn't worry about the thrust line at all, except in relation to the fuel tank. If moving the engine up or down helps get it positioned better in relation to the tank, then I always do it. Don't worry about the line on the plans. Jim

weathervane

Dave, I can not help with your fuel tank. I do have a question, has it been an easy kit? Is it hard to assemble? I have a 4*40 just waiting to be opened. I don't want to kill my first kit.

Good luck
Andrew

ChuckW

Just take your time and study the instructions and plans. This is one of the best building kits that you will find. I've personally built three.

As for the tank, I've always used a Du-bro 8 oz. tank. it gives more than enough flight time. Two engines were upright and I left the position as-is. The last one I modified for a side-mounted engine and I actually lowered the tank slightly to get it inline with the carb.

Penuts

First of all you must be able to remove your tank so dont block it in.
The best way iv'e found to install a fuel tank is to use foam rubber,slide your tank in and stuff foam rubber around it, that way you can lower or raise it to any height you wish, and it also prevents vibration to your tank and prevents air bubbles. That frame you made for the tank looks great however you dont want your tank solid mounted,use the foam you wont go wrong.
Iv'e had two 4 stars, one 40 and a 60 size,, there a great flying plane,good choice.click on my name you can see a pic of my 60 size.

blw

My Feedback: (3)

Don't worry about the tank height. It is a bit low, but not that low for a two stroke. Yes, side mounted engines are okay but they're not necessary.