profile tank mount

Share your ideas: How to mount plastic clunk tanks on profiles???
( ways that work, and still look decent )
Have tried rubber bands, metal straps, but it looks like cr#*!*#!!
Throw in your thoughts on vent, pressure, and pick-up tube location.

By the way, got another ST46 in the pathfinder ( re:hourglass help )
using APC 11/6, and it is flying good. Thanks for the help. DRM

I agree with the way plastic clunk tanks look on a profile. Not a pretty sight. Do you have to use them?
Brodaks has a large selection of nice metal C/L tanks. I have ordered several from them and am very happy with the quality and looks.

The tank is usually on the farside of the airplane and you can't see it whilst flying. I have never used a plastic tank, but I see that they are used with great success by flyers of all skill levels. They are available at your LHS, and seem easy to set up so they work well.

I agree that they are not the most attractive but I don’t think the metal ones are all that lovely either. I wonder if you can dye them? I usually just use the wire and rubber band approach but that is hardly elegant. Anyone know of a glue that would work with the clunk tanks? You could glue them to a piece of plywood and then have mounting slots so you could adjust them.

I prefer the GRW uniflow metal tank obtained from RSM and installed as per Larry Cunningham's build a better profile method. I cutout the area between the beams, shim the tank from the bottom with balsa. The tank works best when at its highest point. Then install with clear rtv. And paint if you like.

Check out the difference between a metal and a plastic tank in flight

Screw it! I mount mine outboard so I don't have to see them

I use onle Plastic c;unk ankd.modified for uniflow.

The best bet, IMHO is them rubber bands, with the tank's smaller side on the fuse.

Put a piece off sponge beteen the tank and the fuse, it'll sampen vvibration

I use a thin sandwich of ply which contains 2 'U' shaped straps with hooks for bands. Elongated holes at each end make the whole assy adjustable. Hope photos make it clear
Adrian

Build a plywood tank mount similar to what is shown in Adrian's post above except instead of the wires for rubber bands, just glue the tank to the plywood with silicone adhesive (RTV). The slots in the plywood mounts allow up and down adjustment to even out the engine run. Eric Rule at RSM makes such a mount and assures me the RTV tank attachment to the mount is permanent.
Steve
The older I get, the better I used to fly!

Ripped from another thread:

Following is not the only way to attach tank to profile fuselage, but I like it.

Buy Gold'nRod tube-in-a-tube pushrod system for RC models. The larger size which accepts links threaded 4-40 is preferred, but 2-56 works fine. Also buy a few pieces of wire which are threaded on both ends, size and pitch to match former.

Locate four holes, two top, two bottom, which position tank properly, plus room for adjustment. (Always up as much as 3/8" with a Fox 35.)

Drill holes in fuselage with 7/32" drill, assuming use of suggested 4-40 size tubing. Holes must be at least 1/4" in depth.

Remove inner yellow (golden) rod, discard outer sleeve. Cut four (4) short pieces of rod.

Roll rod across flat surface with sharp knife held at an angle such that grooves are cut into flutes on rod. Helps glue get a solid grip.

Pound rod into holes. Dribble thin CA on rod. Wait for it to kick.

Trim excess rod away from fuselage.

Bend suitable hooks in threaded rod. Screw into the chunks of plastic rod now embedded in fuselage.

Attach tank with double-sided tape. A good hardware can supply, it is black, 3/8" wide, 1/16" (or so) thick, normally used to mount window glass in aluminum frames.

Rubber bands for the (appropriate) belt-and-suspenders approach.

Better is loop from good-quality (Prather) silicone fuel line. All-thread rod, or simply a bolt with head cut off makes decent joiner, secure by wrapping with wire.

You'll have to fiddle to get length correct, but this type of loop won't break 18 seconds after getting hit with two drops of fuel and a little sunlight.

As a side note, a little experience in using either 2-56 or 4-40 Gold'nRod tubing as a substitute for blind nuts for all but motor attachment will keep you busy for months. Great trick, not original with me.

Finally, tank mounting on profile models is ugly because it is supposed to be ugly. It's punishment for taking the easy way out. If you want smooth lines, uninterrupted by a naked container of fuel, a built-up model is an excellent choice.

Profiles are easy? Since when?
I just use a metal tank and paint it to match the rest as close as I can.

Use niether, just run the fuel line alongside yer control lines, and hook the tank on your beltbuckle. The most important thing, is the type of beltbuckle you use. A led zeppelin buckle is highly prized for planes flyin at around 63.654 mph. Where as a Johnny cash buckle will eek out a fine run at about 63.165 mph.Do not use an ozzy buckle or your plane will only fly backwards, at only 162.666 mph. WHAT ME WORRY--Paul

Knightflite, You just blew all my secrets. I once tried a Lynyrd Skynyrd belt buckle, but my planes kept crashin'.

Steve, next time, try a Stevie Ray Vaughn buckle. (hello D.G.)DRM

>Steve, next time, try a Stevie Ray Vaughn buckle. (hello
>D.G.)DRM

Spitfire1, The worst buckle is the Payne Stewart. Plane ran away all day and finaly augered-in. I thought I was gonna have to get someone to shoot it down.

rough up the plastic with coarse sandpaper, clean the side of the plane with prep sol, squeeze some rtv between the two and press together. Tape overnight and you have a nice installation. Don't do this if you are going to fiddle with the tank height. Once it's glued, it's there until you peel it off.

Attached are some pictures of the tank mount I made for my Lightning Streak derivative. The tank is a two ounce Hayes modified for uniflow operation. I wanted a mount that would be secure, light weight and sanitary. I do not care for rubber bands so this mount uses cable ties- two for redundancy. The mount also cocks the rear of the tank outboard approximately 3/32 inch.
The mount is a glue-up of three moldings of carbon, glass and epoxy. The contoured “tub” which holds the tank was molded directly on the tank using the old Hobbypoxy “balloon” method. The mounting base is made from a “tunnel” section and a flat plate. The weight of the complete mount is 5 grams.
It took a bit of work to fabricate the mount but it was not difficult. It functions well and I’m quite satisfied with the way it turned out.
Derek Moran

How do you secure those 2 nipples on the side of the tank.
Are they glue in? What type of glue?

>How do you secure those 2 nipples on the side of the tank.
>Are they glue in? What type of glue?

Heman,

I asked, answer given further down the line.

If you're thinking of doing this, Derek makes it work, but the Tettra fittings I mention were designed for exactly this sort of thing.

And wait until you see what is planned for a 3-ounce Hayes tank!

Here is a shot from the in-flight video that shows how I mount clunk tanks on a profile. The black straps are small plastic wire ties. I use small screw eyelets available at most any hardware store. Open up the eyelet a little so you can get the wire ties in the loop. Drill a pilot hole, fill with epoxy and screw right into the side of the fuselage.

If you make the uniflow vent so it is a hard tube that goes about half way back then turns to the outside you can adjust the height of the vent instead of moving the tank. I also put a bend in the vent where it exits the tank so I have some leverage to adjust the height of the uniflow exit inside the tank. I stole this idea from a post on this forum and it works great. This setup was conventionally vented and either clunks are not as critical or I just got lucky with the tank height because it runs the same upright and inverted.

This is the easiest way I have found and it doesn't look terribly bad.

I bolt the tank by a tongue ( little brass sheet soldered to tank ) and then I just paint it. claus

Hi Claus
What's the plane and motor. Looks like a PAW to me. I use a few PAW's and love them to bits! You may be interested to hear I have one of yr designs in my stable - a Big Tiger with a Saito 40 on the front. I have to admit I took a few liberties with yr excellent design but it still flies like a dream - I'll be on our field tomorrow morning (Sat) with it if the weather is OK
Regards
Adrian

Oooh! Derek wins this round. My stuff looks so trashy compared to his setup. Which is also light.

Derek, what are the doo-dads which allow punching holes in tank and then fitting various sorts of outlets (or inlets, of course)?

I am using something similar from Tettra, a little cooler as they offer ends with are bent 90 degrees. Plus the normal straight shot out.

And why is the tank oriented the way you have it? I would think flopping it over on its wide side to be better.

(Not being a smarty. Have a mild bias against plastic tanks, thus I do not understand them very well. In fact, most Things Stunt I don't understand well, although I'm constantly working on it.)

Thanks Dan- good eye.
The tank is oriented horizontally to minimize the change in fuel head as the tank empties. I know uniflow venting is intended to accomplish the same thing, but I wanted to optimize as many factors as I could. The engine is easily capable of drawing fuel from the added outboard distance of the fuel pickup.
The fitting you see are Thunder Tiger pressure fittings, the ones that come installed on the mufflers. They are screwed directly into the tank wall. The process of getting strong (well, strong enough) threads in the thin nylon must be done carefully. I first extrude a pilot hole inward using a heated piece of 1/16 music wire. The wire has a roughly spherical tip ground on the end. The object here is to move the material aside, not remove it. The wire is heated just above the melting temperature of the nylon; no smoking, no flames, just gradual displacement of the material. Next the hole is "tapped" with a socket head cap screw whose thread matches the pressure fitting. The tip of the screw is ground to a conical point. The screw is heated, again to just above the melting temperature of the nylon, and screwed in just until full threads are formed. At that point I quickly cool the screw by squirting it with canned air- held upside down so the liquid air comes out.
Finally, the fittings are installed with .03 thick silicone gaskets. The material is approx. 30 Shore-D and is cut with sharpened tubing.
A word about the configuration of the tubes. The capped fitting was my first attempt at placing the uniflow vent. It proved to be too close to the fuel pickup, causing some inconsistencies in the engine run.
I have since bought some right angle pressure fittings intended for tuned pipes and other tin-wall applications. The Tettra fittings are nice since they are radiused and will cause minimal pressure drop if used for fuel feed.
Stay tuned: I'm going to rig up a 3 ounce Hayes for my Skyray/FP.20. I'm going to hard-plumb it instead of using the clunk. It will also be mounted "backwards", with the round part outboard toward the rear. Not quite as radical as your cylindrical tank mounted through the fuselage, but certainly different.
Derek

Just to stick my nose in here, it is a GeeBee Model Z, and that sure looks like a PAW to me too! Diesels are far more tolerant of tank design or (mis-design!) than glows are, at least all the ones I have had were.

Derek,

One has to wonder if your tricked-up Hayes 3-ounce tank was easier to draw than it will be to actually get those fittings installed. Better you than me...

I have a lot of interest in knowing if this works. It looks just about weird enough to work well, but as I have yet to run down one of these tanks I am still using Du-Bro 4-ounce and Pylon RST-4 tanks mounted on the inboard side of the ARF Flite Streak fuselages.

Incidentally, prompted by your comment I did recently mount a Du-Bro 4-ounce number to an ARF, tank oriented as per your instructions, still on inboard side. Good runs. Simple. Cheap. Reliable. Repeatable.

Help me, as what I really want in a tank for my ARFs is something expensive, complicated, unreliable, not repeatable. And it must deliver really bads runs, of course.

Tettra fittings seem to be a *lot* simpler than what you are doing.

Dan,
Adding the fuel fittings is really not that big a deal. You have to be careful, but we're used to that. Modifying these plastic tanks may be a quixotic adventure, but hey- it's a hobby. Based on my sample of one (the Hayes 2-ounce), adding custom feed and vents is a success. The tank is light, cheap and reliable. So far so good.
My next step, after the 3-ounce shown in vague detail above, will be to reshape polyethylene bottles into proper stunt tank shapes. I think this can be accomplished by heating them and blowing (or sucking) them in a female cavity mold; install a couple vents and voilà.
I'll let you know how the Hayes 3-ounce mods work out. In case you haven't guessed, I enjoy these little projects-within-projects. I bought a little sheet metal shear/brake from MicroMark to help with the tank mount. . .
Derek

Derek,

I find the idea of placing outlets and inlets in various spots of our tanks intriguing. Actually, I have done this before, but only on RC Pattern models and with the Tettra fittings mentioned earlier. Which are indeed easy to work with.

Still, as you have no doubt found, the slant-front tanks solve some problems while creating others, and this applies to the tanks I am currently using, Pylon RST-4 and Du-Bro SS-4 units. (For the uninitiated, these tanks have a kinda flat face, all tubes going forward.)

The big deal for me is the most unhandy plumbing for muffler pressure. Thus use of Tettra fittings as I can just plug one in top, left corner of tank, using it both as dump for muffler pressure and in venting overflow during filling. This also very neatly sidesteps the hassle of snaking brass over-flow tube through tank opening.

What I discovered last night is that the Du-Bro tanks accept drilling quite well; no boogers around drilled hole, no rim-shots to prevent seating whatever fitting one might use, no problem. At least in using a new drill bit the hole was as nice as if it had been punched through with a sharp die.

The material in Pylon tanks has never responded as well as desired, although I do not know about Hayes tanks.

Question: How long is the Hayes 3-ounce unit? Both with and without protruding snout.