Hi!

I'm just put in the clunk into my 14oz GP tank. When I wiggle the tank around.. the clunk seems to be moving well side to side.. but when I lower the front of the tank.. the clunk has a hard time dropping down to the front.. the walls on the top and bottom kinda hold it in mid-air.. and the silicone tube doesn't want to bend.. If I really shake it good.. it'll fall then....Is this going to be a problem flying my plane downwards and upwards?

I cut the silicone tube to exactly 3 5/8.. and stuck it firmly to the end of both nipples.. just like the instructions said....so pretty much I know that I followed the instructions correctly...

-eugn

Try using smaller wall tubing to help it bend. Or just plain small tubing may work.

thanks.. but I'm still really puzzled, why it doesn't work with the original tubing?.. Great Planes makes good tanks.. and I'm sure a lot of you have them.. and didn't change a thing...

Maybe it's supposed to be that way? Or maybe some of you didn't check if the clunk goes down when you tilt the thank?.. I dunno... I really want to stick with the original tubing.. since GP wouldn't give me tubing that's EXTRA thick.....

i dunno


maybe it'll go down, when there is fuel?

AHHH!
all these little things.. All I want to do is put my tank in and go on with my build

-eugn

i think i got something!
sortof!

I've been running, and spinning like a fool with the tank in my hand trying to immitate flight.. what I found out is that Momentum will move it.. but that solves half the problem..

I hold my tank and move it forward fast.. and then suddenly change it's direction to DOWN.. the momentum is the opposite way.. so the clunk stays up high.. when it really should be down.. now, when the acceleration has stopped.. it's still up.. well because that's my problem.. it doesn't drop by it self.. but.. when I suddenly pick up my tank up, from a dive.. the momentum drives the clunk down....

so i'm still pretty confused...
so the question now, is.. should the clunk fall down by itself.. or will some forces in flight + the fuel itself drive it down.. when the plane is flying downwards?





-eugn

I could be wrong, and it doesn't seem all that logical, but as far as I know, clunks don't move to the front of the tank, just the top and bottom at the rear of the tank. When you're flying straight down you probably don't need much fuel, and there's quite a bit in the tubing itself.

In fact, if you're having trouble with the engine running after a crash or hard landing, one of the first things to check is that the clunk has been forced to the front of the tank, since if that happens, it will generally stick there, not good.

you're probably right... i'll just put it in, since i've done everything EXACTLY as the instructions specify....

but it would seem logical to have the clunk move everywhere..

eugene

You dont want the clunk to move forward in the tank.

You doing it correctly so far.

you have the clunk correctly,you do not want it falling forward,stick it in the plane and do some flying.

-eugn

thanks for clearing it up!

-eugn

It is a good idea to make your clunk so that it CANNOT go forward. an easy way to do that is to put a stiff section between the clunk itself and the point that attaches to the tank inlet (outlet).

i actually would prefer to leave it as it is.. I rather have the clunk move forwards in high momentum cituations... reason for that is i'll be flying pretty high sometimes.. and I would want to lower my plane fast.. so for about 10-20 seconds.. the plane will be facing downwards.....

Ditto what Rodney said.

Sometimes if you have an abrupt landing (or minor crash) the clunk can get thrown to the front of the tank (I've had this happen). Next thing you know, your plane is going dead stick every time you nose it up.

A stiff piece of plastic tube (or brass tube), inside the tanks feed line will prevent this from happening.

The clunk will not move forward, in a proper install.
If it does, you'll find problems later, on a takeoff or other vertical maneuver. Trust me.

The reason the engines don't stop on the downlines is that it takes a lot less
power to fly straight down than straight up... and you're typically pulling UP hard, long
before the fuel in the fuel tubing is fully consumed, anyhow.
(If not, you'll probably hit the ground before you hear the engine go lean)

Checking for the clunk in the back of the tank, versus the front, is a very helpful
post-hard-landing thing to check. If it's stuck up front, you may be fine for a couple
minutes, while the tank is full... but after a bit of burnoff, it'll bite you on a touch-n-go or something.

well.. as of now... or before even.. by following the instructions the following was achieved: The clunk does not move down by lowering the tank vertically... it will move down.. if I wip(and i really mean "WIP") the tank downwards.. the momentum will move the clunk down...it'll take less of a wip upwards to bring the clunk back... so even before my questions in this thread.. i had everything correctly...

what i'm trying to say is that it'll not move but it self.. but rather with a big wip downwards...

I would put a brass tube in as you guys mentioned.. but i don't have the material at hand.. and i really believe that it won't move down by it self...

i also noticed.. than you can check if the clunk is in the right position by tilting your plane left and right.. you should hear clearly the clunk hitting the left and right sides of the tank... i'll prob do that everytime before each flight.

thanks MinnFlyer for that pic.. your illustrations are very helpfull....

thanks to all for your great responces...

You can also put a piece of drinking straw over the tube to keep it from running forward.
Ed M.

Another thing to consider, and maybe I am a wimp, but I have had a wing fold on me pulling out of a downline at full throttle. So I pull the throttle back on downlines now. So I don't begin to use all the fuel in the line at idle. The worst part is, it was not my plane. Garry

bentgear: drk straw is a great CHEAP soluction.. is it Fuel Proof?

$ircra$halot: not your fault.. it wasn't your plane.. he probably built the wing joints poorly..


-eugn

You are exactly right in doing that. With smaller planes it isnt totally needed but when you start getting into bigger planes its mandatory.

Its a good habit to get into. I tell that to anyone I teach.

ebeygin, I think most are fuel proof in glo as well as gas fuels or a least everyone I have tried is. Several sizes available.
Ed M.

Let’s not forget what the clunk was originally designed for, in that, it is supposed to extract almost all the gas out of the tank. And I agree with some of the previous posts stating it’s not supposed to move ‘forward’, rather move on a vertical and horizontal lateral axis. If it does move forward, your to limp (no pun intended) or you’ve just crashed and who cares if you can get all the nitro out of the tank…..OK guys, stay away from that previous comment….

Okay, what the heck does that mean? If you can imagine looking down the line of the pickup and while viewing the back of the tank, think of an X, Y grid. The clunk should only move left to right or up and down, within 360 degrees.

You could use a smaller ID fuel tubing, but that might not be the answer you’re looking for (Sorry Coulter_Dean), as you could be restricting the amount of fuel to your engine. Just use what was provided with the tank, hold it vertically with the stopper secured. Now if the clunk hits the back, trim off 2 mm at a time and check again. You know your fine when the clunk can move around the bottom of the perimeter. If you’re still insecure, trim as needed…