Perfect Tanks. Please enlighten me

Is it the pipe coming from the top of the tank midships that you're referring to as the "vent"? That one is the feed pipe to the engine. The upper one on the right side of the picture is the fill pipe and the lower one to the right is the vent.

GallopingGhostler wrote:Can't answer your specific question there, but many photos were posted from personal accounts in Photo Bucket, until they went exclusive pay only for storage may be 7 years ago. (Their fee structure was too high for me, for the small amount of photos I posted monthly.) Photo Bucket deleted their free storage taking many free accounts including mine with the deletion. Yahoo Groups was disbanded and deleted about the same time, taking with it a wealth of photos, too. Ditto with Geocities.

The only photos that remain are those with valid links (fewer and farther between) and those posted using this forum's photo feature.

Its a shame the pics were deleted for sure. I would have posted my question there but ive heard thats a problem for some.

What you have is a wedge tank for control line use. (Although, if oriented with the wedge point down and the vent and fill nipples going right and left can be used in Free Flight and R/C.)

The angled tube ends in the back wedge corner, so that the engine can draw fuel until it runs out. What you describe sounds like the soldering joint sealing the tube to the tank and holding it in place has failed. This can be caused by a number of things, cold solder joint (solder wasn't heated sufficiently, so solidified instead of cleanly wicking and flowing around the tube and tank. Another is if tube was moved prior to the solder solidifying, or insufficient solder was used.

These tanks are easily repaired if you have a soldering iron or gun, or small butane torch, and the right solder and flux.

Oldenginerod wrote:Is it the pipe coming from the top of the tank midships that you're referring to as the "vent"?  That one is the feed pipe to the engine.  The upper one on the right side of the picture is the fill pipe and the lower one to the right is the vent.

It was the filler tube that was loose, the one coming out the top of the tank on the far right side. Technically, it should have no effect, but it was enough to make me remove it and not want the tank anywhere
near my plane. I've heard enough stories with the quality of these tanks not being good. I should also point It was an old tank, and not the new ones Cox international sells.

GallopingGhostler wrote:What you have is a wedge tank for control line use. (Although, if oriented with the wedge point down and the vent and fill nipples going right and left can be used in Free Flight and R/C.)

The angled tube ends in the back wedge corner, so that the engine can draw fuel until it runs out. What you describe sounds like the soldering joint sealing the tube to the tank and holding it in place has failed. This can be caused by a number of things, cold solder joint (solder wasn't heated sufficiently, so solidified instead of cleanly wicking and flowing around the tube and tank. Another is if tube was moved prior to the solder solidifying, or insufficient solder was used.

These tanks are easily repaired if you have a soldering iron or gun, or small butane torch, and the right solder and flux.

yea, i got a nice silver solder joint on that tube now and also tested it for leaks. I do remember it having erratic engine runs which is the other reason i decided to go the bladder route. I'm still on the fence on which one to go with, as Ive now had issues with both methods.

To get consistent runs you either need a uniflow tank or a chicken hopper tank.

Here are my uniflow tanks mounted to my Enya 06 glow and Enya 06 diesel.
This is my setup for R/C Texaco for SAM (Society of Antique Modelers).
The tank is 14cc and with my Enya .06 glow engine I get 12 minutes motor run time (consistently).
The rule for that class restricts the use of muffler or crankcase pressure.

This photo of my Enya 06 glow shows the uniflow tube up over the engine to get "clean" air (from the prop) to push air into the tank. The bent tubing goes to the bottom of the tank -- above the fuel pickup (the wedge -- "Vee"). The fuel is sucked up from the bottom of the wedge to get every drop of fuel. I cap off the overflow vent so the bent pipe will pressurize the tank from the prop wash.



With the Perfect tanks, I usually cut the vent and fill pipes at an angle towards the prop so the prop blast pressurizes the tank.
If you had a muffler, you could pressurize the tank from the muffler.

Kevin, I know I mentioned a tutorial to you in regards to simplistic bladder use. A tank on a TD is not out of the question. The Perfect brand tanks should really be called Not so Perfect. I'm not a fan of the tank you show due to it's plumbing. I replumb so that the pickup is on the bottom . Seeing that the fuel has to go up and then down and then back up to the venturi. While moving it to the bottom is the same inverted, you spend most time upright. I also prefer copper over brass which is always what Perfect used. They used cheap tubing which will split and it splits internally because THEY NEVER solder the pickup inside the tank. This causes harmonics which work hardens the tubing making it even split faster.

               In addition, no one in that manufacturing plant could care where the pickup even ended. You can open up 10 different tanks of the same style and all of them would be different where the tubing ends. While I like the Pittsburgh seam used on the back of the tank, it still leaks and I have had multiple leaks with new out of the box tanks. Far better than the crappy way Brodak laps the material which is the worst thing you can do with a solder joint in this application.  The solder they use is complete crap. Brodak now has the equipment and the same crap if not worse is being used. These tanks are built on a hot plate with solder pellets. No one is sitting there individually assuring all seams are completely cleaned and soldered. Use a 2 oz. syringe and pressurize it underwater like your trying to pop it.

     The wedge design is somewhat problematic and if made into a uniflow design it becomes even more problematic. I believe it's the way the tank gets narrow because it causes internal turbulence from the uniflow against the wall of the tank making bubbles that don't exactly allow for a steady run.

     For speed,  I've always found square or coffin shaped designs to work the best. What I've had happen on launch with the wedge is that the engine wants to go immediately lean or try to quit, then as it quickly slows, it grabs fuel and it's off to the races again and then half way through the tank it begins starving for fuel and going over lean.

        This is due to the width of the tank and the projection of the venturi from the profile body. If you sink the tank to the inboard side in the fuse, you can align the centerline of the tank better with the centerline of the venturi. Tank shape is everything and it's far better to use a narrow long tank on a profile vs a short wider one because your not fighting centrifugal force.

         The other thing that may help is to use engine offset on a profile as this tilts the venturi outboard a few more degrees getting it closer to tank centerline. I personally don't like any kind of engine offset but this is one time I'm in favor of it. One other thing I have done is to flip the gold anodized needle valve holder over. This also changes the distance where the fuel enters the engine. This might require a slight bevel on some to insure the venturi is holding it down square.

Ken, and everyone else that replied, thank you for your help. I appreciate it.

Kevin

@ Ken, ya, the perfect tank with the engine feed pipe coming out the top center of the tank is perplexing, having to suck the fuel up, around and then down again. It would almost seems better if the tank was flipped around and mounted on the inboard side of the fuse. The other suspect could be bad fuel. I've had the exact same set up on a Dick Sarpolus Akro bladder fed TD 049 and it was easy to start. I wont give up though. Sometimes you just need to step away. Process of elimination. I will win though

Knowing what type of flying your trying to accomplish is most helpful. Stunt, speed, sport. Yes, any tank will generally start and work to a degree. The problem is that  due to the size of the venturi of the TD, one being a sprinkler style, the throat diameter is very large. The engine is already at a disadvantage due to lack of suction so to speak. When mounted profile, the width of the tank is farther outboard increasing the engine's inability to draw fuel. Now when you start going around in circles the engine is now struggling. As mentioned, uniflow can assist in regulating some of these issues but the problem really is in the shape and width of the tank. This is what makes a bladder a optimal choice. Tank height up and down and side to side is not relevant to the bladder. In addition, maneuvering isn't a problem because the engine has fuel at all times.

               A full body plane generally doesn't have these issues because the engine run isn't compromised due to the tank being directly behind and inline with the engine. The closer you can bring the pickup to the engine centerline, the better off you are. Pat King designed some slab winger 1/2A's, He has the engine's offset to the outboard side. While those designs use integral type Cox Bee's, this is a ideal situation to making a profile work with a radial mount. The other option is to sink the tank into the profile fuse. Now that you mention mounting inboard this is going to also prove problematic.

            When mounting a tank inboard, the problems take a 180 deg turn of events. In theory this is what somewhat needs to be done but the tank is too far inboard now and this is what happens. You have to launch the plane screaming lean and then it richens in the air due to centrifugal force. The problem is that speed changes the run drastically and when you want to the plane or expect the plane to go slower, it charges screaming lean. This now means the tank needs to be moved more outboard which it can't do because it's up against the body. When I designed some of my stunt planes, I have the tank mounted outboard side.  I left enough clearance between the beams to sink the tank and about 1/8" is projecting off and out the inboard side. Not only is up and down need to be adjusted, so does side to side.

                I don't exactly know what issues you were having with the bladder, I can only say it's truly much simpler than a tank in terms of making it work. From memory I recall you had some sort of container mounted to the side of the plane. These things while looking neat can generally cause more of a problem due to the false pressure created within the container.

Ken Cook wrote:Knowing what type of flying your trying to accomplish is most helpful. Stunt, speed, sport. Yes, any tank will generally start and work to a degree. The problem is that  due to the size of the venturi of the TD, one being a sprinkler style, the throat diameter is very large. The engine is already at a disadvantage due to lack of suction so to speak. When mounted profile, the width of the tank is farther outboard increasing the engine's inability to draw fuel. Now when you start going around in circles the engine is now struggling. As mentioned, uniflow can assist in regulating some of these issues but the problem really is in the shape and width of the tank. This is what makes a bladder a optimal choice. Tank height up and down and side to side is not relevant to the bladder. In addition, maneuvering isn't a problem because the engine has fuel at all times.

               A full body plane generally doesn't have these issues because the engine run isn't compromised due to the tank being directly behind and inline with the engine. The closer you can bring the pickup to the engine centerline, the better off you are. Pat King designed some slab winger 1/2A's, He has the engine's offset to the outboard side. While those designs use integral type Cox Bee's, this is a ideal situation to making a profile work with a radial mount. The other option is to sink the tank into the profile fuse. Now that you mention mounting inboard this is going to also prove problematic.

            When mounting a tank inboard, the problems take a 180 deg turn of events. In theory this is what somewhat needs to be done but the tank is too far inboard now and this is what happens. You have to launch the plane screaming lean and then it richens in the air due to centrifugal force. The problem is that speed changes the run drastically and when you want to the plane or expect the plane to go slower, it charges screaming lean. This now means the tank needs to be moved more outboard which it can't do because it's up against the body. When I designed some of my stunt planes, I have the tank mounted outboard side.  I left enough clearance between the beams to sink the tank and about 1/8" is projecting off and out the inboard side. Not only is up and down need to be adjusted, so does side to side.

                I don't exactly know what issues you were having with the bladder, I can only say it's truly much simpler than a tank in terms of making it work. From memory I recall you had some sort of container mounted to the side of the plane. These things while looking neat can generally cause more of a problem due to the false pressure created within the container.

Hi Ken, the problem i had while using the bladder was getting the engine to start, and getting the engine to run long enough to get a needle setting. I tried all the ways you mentioned and it would not keep running. This is why i am suspecting it could be bad fuel.
Since Ive already resoldered the tank, pressure tested it and flushed it out, and re- installed it, o
im going to head out with different fuel, a stock hi perf glowplug and hope for the best, if that fails, i will remove it and try the bladder without any false pressure holding fixture, something semi transparent so i can verify the bladder isnt being restricted in any way. Will let you know how that works out. Also the type of flying i plan for using the plane is for a stunt, as fast as i can get it to go.

Got it. The first run Fuel was spewing out the top vent. The 2nd run i capped off the top vent This is the result. The 3rd run i rolled out the lines and flew it, in some gusty wind.
https://youtu.be/hRESQbZ2GWs

kevin king wrote:Got it. The first run Fuel was spewing out the top vent. The 2nd run i capped off the top vent This is the result. The 3rd run i rolled out the lines and flew it, in some gusty wind.

Ken's got a much, much, better handle on tanks than I do, nothing beats experience, which he has a lot of.

One thing I noticed in your first video, that the engine RPM sags when holding the nose up. Basically, the suction must lift the fuel a couple inches (end of tank pickup) vertically. The half-A's, because of their small volume, don't have the suction that a larger engine has.

This is what made the Cox engines popular besides cost. The integral tanks on the reed valves and tank mount for the Tee Dees made the fuel pathway as short as possible, eliminating fuel feed problems. Rule of thumb I learned with the half-A's was to keep the fuel lines as short as possible and tank as close as possible.

Your tank is close, but being long, extends the length of fuel path. All the Perfect and Kap-Pac tanks I have, most are short tanks. Also because of centripetal force (physics term, some refer to as centrifugal) by the CL circle, there is is also the horizontal travel distance, which makes the fuel heavier by the forces. I've seen some rectangular tanks mounted on the left of the profile fuselage instead of the right, which would minimize this distance with the pickup in the lower back corner closest to the fuselage.

But, it was good you got the plane started and flying. The plane shows excellent craftsmanship, too.

GallopingGhostler wrote:

kevin king wrote:Got it. The first run Fuel was spewing out the top vent. The 2nd run i capped off the top vent This is the result. The 3rd run i rolled out the lines and flew it, in some gusty wind.

Ken's got a much, much, better handle on tanks than I do, nothing beats experience, which he has a lot of.

One thing I noticed in your first video, that the engine RPM sags when holding the nose up. Basically, the suction must lift the fuel a couple inches (end of tank pickup) vertically. The half-A's, because of their small volume, don't have the suction that a larger engine has.

This is what made the Cox engines popular besides cost. The integral tanks on the reed valves and tank mount for the Tee Dees made the fuel pathway as short as possible, eliminating fuel feed problems. Rule of thumb I learned with the half-A's was to keep the fuel lines as short as possible and tank as close as possible.

Your tank is close, but being long, extends the length of fuel path. All the Perfect and Kap-Pac tanks I have, most are short tanks. Also because of centripetal force (physics term, some refer to as centrifugal) by the CL circle, there is is also the horizontal travel distance, which makes the fuel heavier by the forces. I've seen some rectangular tanks mounted on the left of the profile fuselage instead of the right, which would minimize this distance with the pickup in the lower back corner closest to the fuselage.

But, it was good you got the plane started and flying. The plane shows excellent craftsmanship, too.

I appreciate the feedback. Yes, I can see Ken is up on the expert level, and he always is willing to help others. Thats a huge part of the hobby, helping others and sharing information. Me, i just finished uploading over a 1000 videos on The Walt Brownell Channel, and it would not have happened without other people. The vast majority were VHS tapes that had to be converted to digital. Now that the channel is done i can spend more time focusing on building, flying and having fun. As for future plans for Tsunami, I will switch out the tank and run it on a bladder. Thats based on what others have been telling me about TD engines, people like Ken, Paul, and Dan.

Kevin

Kevin, I've been admiring the Tsunami since you started this build. Your painting skills are over the top. I do nice finishing, not that level and certainly not on a 1/2A. I know you were also helpful with the Windy videos.

While I have a lot of tank rebuilding experience not to mention knowledge I've gained over the years, I can only use it as a guideline. I say this because I try to follow my tried and true methods to the letter. I see others show up with what looks like a catastrophe of tubing and everything loose and crooked and it works like it shouldn't.

Added just under an oz of nose weight to under the perfect tank of Tsunami and cured the hunting. Love the engine, its got a nice loud and aggressive exhaust note and gives you that ever so slight ringing in the ears.

https://youtu.be/MbXSvcAPdD4

She has a Good scream going on now / i have commented on this plane before , Very Nice and seems to have good flight characteristics.

Thanks Getback
Oh man, the next flight the connecting rod separated from the piston. Anyone have a one they would like to sell?

kevin king wrote:Thanks Getback
Oh man, the next flight the connecting rod separated from the piston. Anyone have a one they would like to sell?

Sad.  Must have had a lot of slack in the ball joint.  Was that the .051?  I doubt you'll find a replacement.
Otherwise, Here's your best chance.
https://coxengines.ca/top-end/cox--049-tee-dee-cylinder-and-piston.html

Oldenginerod wrote:

kevin king wrote:Thanks Getback Oh man, the next flight the connecting rod separated from the piston. Anyone have a one they would like to sell?

Sad. Must have had a lot of slack in the ball joint. Was that the .051? I doubt you'll find a replacement. Otherwise, Here's your best chance. Cox Engines CA : Cox 049 Tee Dee Cylinder and Piston

Yup, good replacement, it will still be a working engine with the same pickup and go, just a little loss in appearance glory over the grooved piston for boasting during show-and-tell. But, these days, as the old song, The Garden Party by Ricky Nelson goes, "You can't please everyone and so you got to please yourself."

I found the video of Tsunami's flight that has the connecting rod breaking. Not being an expert on these engines, i think the small undersized prop may have contributed to the rod snapping. Engines, i feel need a certain amount of load, and a small prop may contribute to a higher RPM than the engine likes to run at. I could be wrong though. Heres the video:

https://youtu.be/cl1RqEBSkGQ

@kevin king, I gather that you were very fortunate to obtain a replacement .051 cylinder-piston set, which is fantastic (kudos to the kind supplier).

Regarding failure, this is why after a season of flying with my engines, then all reedies, I disassembled, devarnished (back then, nearly all fuel was all or nearly all Castor based) and reset the piston-con rod socket back to no play. As they slowly loosen, the greater the gap, the more the hammering effect.
Of course, back in ye olden days of yore, , Cox engine parts were readily available nearly everywhere, 1960's into the mid 1970's. I could even stop by the toy/hobby area at Sears and buy engine parts. If one was military, was available in the base exchanges and on-base hobby shop. Back then, they didn't have the chronic problem of shoplifting, so they were available on racks in kid's reach. Even us kids had enough respect not to steal, just take what we wanted our parents to buy (or I buy with my pocket money).


Shoot, I could even buy motorcycle tires at Sears in the late 1970's for my 1971 Honda CB100. (Nowadays, they call them "moped tires")  

Mopeds / scooters then:

Photo from https://www.bbc.com/culture/article/20140515-when-two-tribes-went-to-war

Mopeds / scooters now:

Photo from https://www.theguardian.com/uk-news/2019/mar/09/electric-scooters-uk-road-ban-set-to-end

But, the CB100 was more motorcycle than a moped, with 5 speeds and sweet spot of 40 - 45 MPH, I outran a mid 1970's VW Rabbit by 2 car lengths up to 40 MPH who tried to race me at a traffic light on Nimitz Highway in Honolulu back in 1980.)


Anyway, impressed with you posting your experiences of this then and still hot .051 glow engine, and its potential to still perform as it was always intended even into the Schneurle age. The Cox twin ported exhaust twin ported bypasses were advanced for their time.