Tee dee stunt tank

If you could provide some more information, it could be a bit more helpful. How do you know the fuel is foaming. Are you just too lean to start with? What prop are you using? One thing I don't care for with the Norvel tank mount is it's length which could be responsible for vibration which may or may not be the cause. Is this the mount your using? How is this mount mounted to the plane? Are you using wood screws or machine screws? This mount in my opinion is too long and unless properly and adequately secured is placing a good deal of stress on the firewall due to acting like a lever. Unfortunately, this mount can't be used with the cylinder mounted sideways. A Tee Dee prefers to run fast and a larger prop like a 6x3 is going to load it down too much therefore a 5x3 is a better choice for your application. Changing props to different pitches  can also get the engine out of the resonance it's running in if this is the situation.






     The plug on the back of these mounts are notoriously known for failing. A simple pressure test with a large syringe underwater will quickly reveal a failure. These tanks especially leak from the back plug and also the piping. If air bubbles are present, the engine is going to continuously quit as it just won't draw fuel correctly.

Ken, my mouse racer with the TD .051 and the Norvel tank was foaming like crazy with a cut down 5-4 yellow Tornado, and then with a 4 1/4 - 4 APC too. It was balanced. The Tornado maybe not so much. The .051 is more out of balance though from the heavier piston. After the launch, the foam goes inboard. I noticed that on another .15 combat that I have. It would not run good on the ground from the foam, and I had to launch it fast but it would run till the last drop. I checked my Norvel tank for leaks. Ya there is a slow leak after about a second it has lost it's negative pressure. I will have to play with that. The OP can't do loops. The design of the tank won't allow that with the pickup on the bottom. I used a wedge tank years ago on a TD .049 combat that worked fine. I would like to try the balloon tank and have a plan to on a .15 size combat. I hate bladders. That is a good thing to try for the OP. It does give a nice run if you don't mind the monkeying around to start it.

I would certainly agree with the fact that the Norvel mount does indeed have it's pickup too low. This is causing the engine to starve for fuel when it needs it the most in the maneuvers.

All my RC planes have been built with balloon tanks and fuel foaming, or engine starving of fuel in loops and wing-overs are unknown to me. Added is the benefit of the tank morphing easily into the shape of the tank compartment i.e. practically no geometry limitations like with the hard tanks.

A normal party balloon will do but flush it with fuel before use. A stopper with a fill and feed line only will suffice i.e. no vent line to worry about positioning.





In order to best utilize the space in the nose of the plane as fuel compartment,  and not to weaken the firewall with holes drilled in it,  I usually lead the feed and fill lines out from the plane  through the fuselage walls instead of the firewall, so  heat-bent hard plastic tubes for both lines are used to lead the lines transversely  instead of longitudinally out from the stopper. The stopper diameter is big enough for the balloon neck to seal around it tight but you may add a fast zip tie to be sure.

How long does the rubber last? And is the vent line really needed? I want to try an F2D plane with a non pressurised balloon. I bought a bag of extra large ones. I have to make a compartment 90 degrees from normal and away from the bellcrank.  The hard tank I tried quit all the time on outside loops.

Rubber will last years if you do not let fuel thicken inside. Vent line is absolutely unnecessary. The tank collapses under ambient pressure and lets the last drop of fuel leave without pressurization

roddie wrote:Show us a photo.. or describe your fuel-feed/system and we'll be better able to make suggestions. If your experiencing "fuel foaming" it's likely caused from vibration. A simple 1st check, is to check/balance your propellers.. (any that you plan on running on your model) If your model is a "profile" (slab-fuselage).. a "hard-tank" might need to be isolated from vibration. A rigid-mounting might be contributing to your fuel-foaming problem. If you're running a hard-tank, try to isolate it from its mounting, with some foam-rubber cushioning/anything to dampen vibration.

Some RC modelers here run "balloon-tanks". A balloon-tank eliminates any "air" for foam to accumulate.. and provides a reliable suction-feed for most sport applications.. including aerobatic flying.  

Good luck.. and please let us know about your future model-flights.  

Here it is. Nothing unusual. Yes I know bladders run better but I hate them. I wanted to know members'
experience with Norvel tanks as mine is not too good.

My Norvel tank was foaming like crazy too, and quits easily so it needs to be rich. It works if you don't waste time on the ground. Leans out a bit at the end like most other hard tanks. I used the .051 which is an unbalanced engine and I keep the revs up which doesn't help matters, I will go to an .049 at some point. I like the fact that it is the same bolt pattern as the Bees. I mounted mine with 2-56 bolts so it is not from being mounted solid enough. The Cox tanks are OK but any little crash and they break.They also won't be much good for stunts. I am wondering out loud here what is a good glue to seal up the Norvel tanks. The glue would have to creep into the gap where the tubes go, and the backplate disc would likely break if it is removed. Pretty sure CA is not fuelproof. The balloon tank sounds good. It is a limp balloon, not pressurised. It needs a container or housing on a profile plane or a big opening. You picture never showed up so I can't see your situation.

First thing I would do is unplug the top vent.  There is no way for air to get in unless it is different than mine.  My vent faces forward.  I would also flip the needle valve with the ratchet so it is back farther.  It won't be so easy to trim your fingernails.  It will likely still foam though. I am not sure, but maybe you could twist the pickup tube so the rear of it ends up in the centre. It could probably be a new source of leaks though.

To no one in particular; speculation is fine. Everybody has their opinion & I respect that. I carefully read
each reply, sort into fact or opinion or somewhere in between. I am grateful for all your replies. What I
was really looking for was answers with experience to back it. R.E RTF tee dee tanks. I can run a bladder
or a hard uniflow or pressure tank. I have a long knowledge on these.

Ok so I want to try & make the Norvel tank work. Fuel pickup seemed less than optimal.
I bent it about 20 degrees down & reinserted it. Stock position was higher than tank center line.
Photo shows new position.