Small tanks and clunks...
#1
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Small tanks and clunks...
Trying to save some weight on the small planes and realized that a commercial 2oz fuel tank weights in at about 30g...[:@]
I've used the film canister type but then you'll still need a clunk in those, I've tried the sintered ones which seem a little lighter but then the thin fuel line (needed for proper operation of the clunk) couldn't take the strain and split...
What are you people using?
Could a vertical CL tank do the job for sports flying?
I've used the film canister type but then you'll still need a clunk in those, I've tried the sintered ones which seem a little lighter but then the thin fuel line (needed for proper operation of the clunk) couldn't take the strain and split...
What are you people using?
Could a vertical CL tank do the job for sports flying?
#2
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RE: Small tanks and clunks...
I've made small tanks from the small aluminum purse-size perfume spray cans. They sell them in the local dollar stores, and when empty, I simply drill or turn the spray end for a standard tank stopper, which I cut to 1/2 thickness. I substitute aluminum tubing for the brass, and the extra length of the can as compared to a plastic tank, allows the use of a much lightened clunk. These tanks hold about 2oz, but are about half again as long as a plastic tank, but only about an inch in diameter. Of course you can use mousse cans, and other sizes. I have a freon can and a couple of the aluminum beer/pop bottles to try, too...
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RE: Small tanks and clunks...
You can also use pill-cans (dont know or that is a english word)
Use 5/2mm silicone tube for the fuel-tubes and 4/2mm for the clunk-tube.
Here some pics.
Use 5/2mm silicone tube for the fuel-tubes and 4/2mm for the clunk-tube.
Here some pics.
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RE: Small tanks and clunks...
Well, when I was a kid I mainly built and flew free-flight models before I finally got my hands on an ancient single channel rudder-only unit and then finally a two channel radio. Standard fuel tankes for those models consisted of using an adapter to go from small fuel line size to nice big fuel line size and then carefully coiling up the tube from the bottom up around a short length of light hollow tubing mounted vertically in the center of the plane directly at the center of balance. The coil was then securly wound with clear packing tape and then a reducer resulting in a pin-hole sized vent placed in the end where the top of the tube poked out just even with the top of the wing. Fuel take was filled via a vetinary shringe. Worked like a charm basically a fuel tanke made out of a coil of tubing. You could look through the side and see how full the tank was and fill it just the right amount so the engine would run out of fuel when you ran out of farm feild right before the woods started up again. Full tank for single or two channel lasted quite a while depending on tubing and coil size don't thing it would work for extended inverted flight. Used to do a few loopty-loops with the two channel rig an the motor would still be running afterwards but any longer then a few seconds up side down and motor would probably quite running.
Just a though to add to the pile.
Just a though to add to the pile.
#5
RE: Small tanks and clunks...
here is a link to some other idea's http://www.rcgroups.com/forums/showt...nk#post8673949
Go down to post #6 I was having trouble with getting the medium fuel line to work proper in a 2oz. tank so I used andrews idea. But I didn't use the film bottle or the 14g silicone wire I used some 12g silicone wire and the store bought tank and shoved the silicone onto the clunk and the brass tube that came with the tank. A bit tough to get the silicone over the clunk and brass tube but I managed. The clunk now works way better than the stiff fuel tube that would not hit top and bottom.
Go down to post #6 I was having trouble with getting the medium fuel line to work proper in a 2oz. tank so I used andrews idea. But I didn't use the film bottle or the 14g silicone wire I used some 12g silicone wire and the store bought tank and shoved the silicone onto the clunk and the brass tube that came with the tank. A bit tough to get the silicone over the clunk and brass tube but I managed. The clunk now works way better than the stiff fuel tube that would not hit top and bottom.
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RE: Small tanks and clunks...
memories of those old single chanell radios, i had an O.S. PIXIE single chanell set, one push for right rudder and 2 pushes of the buttom for left.
#7
Thread Starter
RE: Small tanks and clunks...
Thanks for the advice and links, I'll see if I can find some silicon insulated wires. A 2x4 mm fuel line seemed to work well but it couldn't take the strain from being fitted onto a standard clunk, I guess I'll start making my own clunks too...
#9
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RE: Small tanks and clunks...
Well I've never used a bladder tank and didn't want to start fiddeling with that too. Don't these have to be replaced after a few runs and if you use the wrong rubber it can damage the plug etc. ?
I think that the film canistor type and a homemade clunk would weight in around 15g, which would be about half the weight of the commercial ones...
I'm not after extreme low weight, just trying to remove some stuping things that I've ignored before. For instance I recently weighted this nice white foam they want you to use for protecting the radio, ooops those are potential weight robbers too! Just by using other left ower packing matterial I saved about 15g and some money...
I think that the film canistor type and a homemade clunk would weight in around 15g, which would be about half the weight of the commercial ones...
I'm not after extreme low weight, just trying to remove some stuping things that I've ignored before. For instance I recently weighted this nice white foam they want you to use for protecting the radio, ooops those are potential weight robbers too! Just by using other left ower packing matterial I saved about 15g and some money...
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RE: Small tanks and clunks...
I was thinking more along the lines of a bladder placed inside the film can tank (or your choice tank). Your pressure return would come into the tank, but stay outside the bladder to help keep pressure on it. The pick-up tube could be a plastic line with holes in it. It wouldn't stop drawing untill the bladder was empty, and NO BUBBLES![8D] It would at least save the weight of a clunk or added weight of brass line etc.
Just a thought. I have one every once in a while, but sometimes they hurt. [8D]
Just a thought. I have one every once in a while, but sometimes they hurt. [8D]
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RE: Small tanks and clunks...
Fond memories indeed freeair of those single channel rigs. If you want a description of the one I used to use go here: http://www.rcuniverse.com/forum/m_7779508/tm.htm
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RE: Small tanks and clunks...
Mr.C, Unless you plan on maintaining inverted flight for 15 seconds or more, you don't need a clunk. 15 seconds is a long time, enough time to do a lap around the typical field. 1/2A engines will run this long with just the fuel that is in the feed line, plus any random splash that gets sucked in.
1 oz tanks can be made to clunk, but fixed pickup tube tanks are less trouble to set up and less trouble at the field.
Low pressure bladder tanks [bubbleless tanks] really are the very best way to go, no possibility of fuel foaming, plus you don't need to reserve room in the fuselage to pad the tank.
I like high pressure bladders, too...but they have their drawbacks.
1 oz tanks can be made to clunk, but fixed pickup tube tanks are less trouble to set up and less trouble at the field.
Low pressure bladder tanks [bubbleless tanks] really are the very best way to go, no possibility of fuel foaming, plus you don't need to reserve room in the fuselage to pad the tank.
I like high pressure bladders, too...but they have their drawbacks.
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RE: Small tanks and clunks...
Mr Cox, a balloon tank would usually need the balloon replaced every flying session. The nitromethane will break them down over a period of time. But, if you take care and remove the fuel after every flight and "huff" it out with the syringe they will last significantly longer. (several flying sessions) Definitely don't toss that idea out. It's one of my favorites! The pro's are almost too many to list, but I'll try.
Cheap - you don't need anything but balloons and fuel line.
Easy - attach the balloon to the fuel line - done! No fancy slotted tubes, the balloon WON'T stop till it's empty!
Light - stick a balloon an your scale, now a film can, pill bottle, etc. For shock value, stick a RTU commercial fuel tank on there.
Quick - remove the air with a full syringe, then make sure only fuel goes back in.
There's probably more, but that's the general idea. There's only one con. You gotta replace the balloon occasionally.
Cheap - you don't need anything but balloons and fuel line.
Easy - attach the balloon to the fuel line - done! No fancy slotted tubes, the balloon WON'T stop till it's empty!
Light - stick a balloon an your scale, now a film can, pill bottle, etc. For shock value, stick a RTU commercial fuel tank on there.
Quick - remove the air with a full syringe, then make sure only fuel goes back in.
There's probably more, but that's the general idea. There's only one con. You gotta replace the balloon occasionally.