Bad Days Flying is NOT better than ................

Yabby Sat Jan 28, 2023 3:38 am

Went out to fly on my own today. brace of nice new finished planes and some reasonably new engines. All tested all run in and run with no problems.
Sun glasses fell off my head and I trod on them, thats my long distance to see elevator before I pull the stooge pin on my launch table. Short glasses fell from top of T shirt in box holding all of the fuel. I suspected this could get messy. Tried to start a known plane on the known launch table, but different fuel tank. With TD when I tried to prop fuel up to the needle, fuel would squirt out of the tank. (Overflow blocked), and the fuel would run back down the fuel line and not stay up by the needle.

Changed planes. Known plane, know engine (TD). Known on Launch table, goes great. One change is new fuel tank. Same thing, wont hold fuel up at needle and when propping over squirts out of tank vent and fuel runs back down line into tank. Couldnt start either TD and keep them running.

Had some known good surestart grey backplates, TD cylnders, run great always and they should hold fuel up. swapped them over to the other two planes. Got them started, but didnt hold tune properly, revving high then low and mainly low. Didnt have any other fuel tanks with me, so I headed home to cool off before I stomped all my planes and engines into the ground.

The tanks I had been using are brand new brodak 3/4 oz wedges. Replaced them with some od brodak 1/2 oz wedges, TDs ran fine, surestart crankcase based engines ran fine. Hmmmm...... The fuel was the same fuel. I have used plenty of 3/4 ox brodak wedges with TD and surestart crankcase based engines in same configs previously and never had problem. I will check the new tanks for leaks!!!! I assume its harder to draw fuel from a 3/4 oz long wedge than a short 1/2 oz wedge but its hard to believe thats the problem. I had the TDs running on some old 3/4 oz wedges a week or so ago. I hope that somehow these tanks dont draw as well as the old ones as I DO NOT want to have to go back to muffler pressure again. I really hope something is wrong with these two tanks.

At least I didnt crash. Got a few flights on 42 foot lines using surestart CK based engines, but they didnt run well enough for me to join all of my manauveres together without a gap between them. which is how I like flying. So it was less than a happy flying session.

Time for a few weeks away from flying I think. Find something else to do. I need a motorbike to build. I want a second hand Yamaha RZ350 so I can put TZ 350 barrels, pistons, head, pipes, carbies, ignition, on it and use it in the hills on the street. Time to try and find the Yamaha RZ350 or Yamaha LC 350. I can definately make them work properly! Old Bugger

Yabby

Ken Cook Sat Jan 28, 2023 5:54 am

Unfortunately, the Brodak tanks are very hit and miss in terms of quality. Generally, the public feels if you buy something it's supposed to be correct and work. Not so with these tanks. Regardless of what you spent, since my first post on this forum, I've stated my experiences with commercially available made metal tanks. If your not taking apart your tank prior to using them, well, you just experienced the inevitable. I've wrote about this so much on here, I'm quite certain a quick search would reveal something.

Brodak uses inexpensive materials. These tanks are made on a hot plate. Solder pellets are placed on top, the entire assembly is fluxed and placed with it's end caps on the tank and left on the plate until the pellets melt. NO ONE IS INSURING ANY THING IS CORRECT. This means that the flux isn't properly cleaned inside or out, the tube heights internally and externally aren't correct or possibly angled. It also can mean the pickup tube is soldered in it's entirety to the rear wall of the tank. In addition, the fitment of these tanks are is if a 10 yr old put them together. The bends are not formed correctly, the fitment of the end of the tank isn't square, the metal is oil canned, etc. Worst of all, the seam on the back of the tank is a lap joint and not a rolled and locked Pittsburgh seam. This isn't always the situation but most of the tanks are lap joints. What this means is that in short order, vibration will kill that joint instantly and it will leak. To make matters worse, the tin plate used on some them has been clear lacquered to prevent rust so if the tank is leaking prior to use, trying to scarify the tank to prep for solder is a major pain in the rear. If you don't get the lacquer off, it contaminates the joint further making a repair even more difficult.

Unfortunately, this is practically all we have anymore. Brodak purchased the Perfect tank equipment and took that line over. While Perfect tanks weren't so perfect, they were better than the stuff offered. It's the end of the road for control line, while it will be around, all of our support equipment is dying fast and this is what we have left to choose from.

First thing is to remove one of these tanks from it's packing and air test it to the point your trying to POP IT!!! If it passes that test, I would still remove the rear end cap and at least clean the crap out of it. Next is to insure that the pickup is soldered correctly to the side wall of the tank at the proper location.

balogh Sat Jan 28, 2023 6:16 am

I believe one can save himself the experience Ken writes about by making soft balloon tanks out of party balloons..I have been making and using them since I returned to modeling 13 years ago, in RC planes with full satisfaction. Maybe the only drawback is you cannot pressurize it from the engine muffler because of its soft shell.For an open placement on a profile CL plane I would put them inside a light plastic casing like a medication fial for the ease of fixture

rdw777 Sat Jan 28, 2023 6:31 am

Hi Yabby, I tell my friends on things like these, You know John Denver wrote a song about that, “Some Days are Diamonds, Some Days are Stones” Very Happy

….I can’t tell you how many planes I’ve re-kitted, Finishes that never cured, Fried the wires, and the list is long lol!

….Take Ken’s good advice and work thru those tanks and prove them out on the bench ( Or check out other systems) and we’ll like to see how well it worked out to fly your planes…..

Robert

HalfaDave Sat Jan 28, 2023 6:35 am

Hi Yabby,

Have you tried (unpressurised) bladder tanks? Work great.
I use the fingers/thumb from latex gloves. Hold up to an ounce.
A bit of tube, a twist tie are the only other things you need.
Too fill, I suck (say 3/4oz) fuel into a syringe. Connect to 'bladder'.
Here is the trick: Hold the syringe upright and suck any air out of the bladder, then fill with fuel. Back the syringe out a bit and will remove (burp) any air in the bladder. The syringe will have the air you sucked out, fuel is in the bladder.
Takes less time to do, than explain it...!
Works for me.
Plus, I feel like a mad scientist using a syringe ! Smile

Only difference is, there is little warning when fuel is running out. Just leans then dies.

Hope this helps,
Take care, Have fun,
Dave

P.S. balogh is faster than me !

Yabby Sat Jan 28, 2023 7:20 am

Hi Everyone, Thanks for the replies. I knew I was going to incur the ( but friendly roth ) of @Ken Cook about this. lol!

He is dead right and few of us probably take proper notice. I have other good tanks at home and I am going to use them tomorrow if it doesnt rain. :-) I have tested the tanks and they dont leak, but that doesnt mean all of the other potential problems dont exist. I dont want by any means to have to use mufflers to get pressure it shouldnt be and hasnt been necessary previously. See how these other tanks go. They are tanks I know are good. Infact I will fly those planes.

The party balloon trick seems to be the go! I need to get my act together and learn to use them and solve a lot of problems! I know there is a LOT to be found on this forum about it.

This type of thing is one of those things when I hate that I fly by myself as I dont have anyone out there to share and bounce ideas off of. and I am very used to doing engineering that way. Fortunately this forum exists and there are plenty of people willing to share and bounce ideas. Thank you all. I Love This Forum!

I reckon I used to make better tanks when I was a kid using dads kero blowtorch and huge soldering iron for guttas and bits of tin plate from cut up icecream containers. and the big bar of solder, bottle of hydrachloric acid, bits of brass tube, what could go wrong................... Lol.

I still want the yamaha RX and put a TZ 350 GP engine in it. That will cure a lot of wrongs. lol!

GaryB
'Yabby'

andrew Sat Jan 28, 2023 10:23 am

Yabby -

Sorry to hear your day at the field was less than enjoyable, but we've all been there. Some days I've cranked on engines that were gems at home and dogs on the flight line -- if sweat were fuel, I could've flown for a week!!! Or I could tell about trying to load the truck in too few trips only to have the storm door slam shut on my wing or ...... well, you get the picture.

Prop your feet up, have a beer, tomorrow will be a better day!

a--

Yabby Sat Jan 28, 2023 1:47 pm

andrew wrote:Yabby -

Sorry to hear your day at the field was less than enjoyable, but we've all been there. Some days I've cranked on engines that were gems at home and dogs on the flight line -- if sweat were fuel, I could've flown for a week!!! Or I could tell about trying to load the truck in too few trips only to have the storm door slam shut on my wing or ...... well, you get the picture.

Prop your feet up, have a beer, tomorrow will be a better day!

a--

Thanks Andrew!!!! Hand Shake

Flying alone, living alone, I find tough. But having the CEF as my CL/RC Modelling Club genuinely helps break that insular attitude/feeling that can come at times from lengthy isolation. It genuinely makes me feel better I Love This Forum!

Thanks!. CEF IS my modelling club. Its funny imagining some of you guys, so exoerienced and knowledgeable having a really dirty day, but I guess thats where the experience and knowledge comes from. "Learning" learning, analyzing, to find what what wrong. makes us better prepared next time. Mistakes we dont repeat, hopefully. lol!

We should understand preperation better from these days! Just having breakfast and when its light enough and the rain stops Im going to try again. not focussed on flights but just good strong engine runs.

Thanks!

Gary
'Yabby'

Yabby Sun Jan 29, 2023 2:57 am

Found the cause of the problem. I had made one other fairly major change that I forgot about. I had shimmed the cylinders on the TDs to turn the ports around as the ports were pointing forward and backward. problem being that the heat from the back one will melt the top rubber bands for the rubber band engine mount system I made. Anyway, removed the cylinder shims and now the engines hold fuel up to the venturi with the plane at any angle for starting and the fuel doesnt run back into the tank. At least I found the cause of the problem! Thumbs Up

I know you can get shim holders and maybe this is why they are made. But its definately the cylinders with the shims not sealing properly. Three shimmed engines all did the same thing. So Im happy that its the shimming thats the problem. Other than a shim holder I dont know any other way to install the cylinder shimms. Using gasket goop comes to mind, but I dont really want to do that. I will have to run without the shims and change all of my engine mounts back to the same as I used previously.

I had previously had some 049 TDs and Cylinders that had the ports facing the sides without shims and assumed that would always be the case. Built three new 049 TDs and all of them point foward/back. Bugger!!!! The rubber band engine mount system was really good, fast and easy to change, add, remove engines, but its no good if the ports face foward/back and melt the top set of rubber bands.

If anyone thinks they know a different way to put the shims on a TD other than using a shim holder or anearobic gasket goop, please let me know! The pressure leak is miniscule, but its enough for the fuel to run back into the tank when starting, and reproducable across three engines. Remove the shim on all three and the problem dissapears on all three. Huh...

GaryB
'Yabby'

HalfaDave Sun Jan 29, 2023 4:52 am

Hi Yabby,
There is no difference, where a Cox exhaust exits. A myth.
Not even, if you want to spread the goo, it will go where it 'castors it's spell'. (pun? not sure)
Performance?
Get it running. A few flights, try a different prop. +/- head shim gaskets. Nitro, if you like burning up glow plugs.
It will run.
Have fun.
I pretend I am in a contest, every flight. If I don't break a prop, I win.
I like swaggering back to the pits, just to fuel up.
It is more fun with others, but,
They will have to beat me.

My perspective,
Dave

Yabby Sun Jan 29, 2023 4:27 pm

Hi Dave,

I only wanted to turn the Cylinder 90 degs to stop the rear exhause burning through the rubber band mounts. Nothing to do with performance.
Mind you Paul Gibault I recall says forwars / back echaust is better fro performance and Im not going to disagree.
Im ok with engines. I just keep my engine mod views for performance to my self to prevent huge aggresive posts in response to being a heretic.

Cheers,
Dude

balogh Mon Jan 30, 2023 12:42 am

Yabby, hot flue gases can be diverted from your rubber bands by a piece of aluminum sheet deflector cut from a beer can, and bolted under the engine mount. Even if you do not have a separate plastic TD mount, just the beams of the fuselage, the tabs of such a mount can be fixed beween the fuselage and the engine mount beams.

This way you can keep the cylinder orientation at any exhaust direction.

Here is my quick'n'dirty , paper template for a beer can aluminum sheet cutting pattern;

Bad Days Flying is NOT better than ................ 16750610

The tabs of the deflector can be drilled for the mounting screw pattern, and fixed between the engine mounting beam and the fuselage..

Bad Days Flying is NOT better than ................ 16750611

Of course you can make it as streamlined as possible to reduce the drag but still deflect gases right at the rear exhaust port..

Empty or full, beer cans are my friends... Beer Cheers

Yabby Mon Jan 30, 2023 5:54 am

Thanks heaps Andras @balogh what a brilliant and pragmatic solution! cheers

That will work perfectly. Thanks so much! and its an easy to implement solution. True brilliance Andras Clapping

Simple and pragmatic and solves the problem. Beer Cheers

GaryB
'Yabby'

balogh Mon Jan 30, 2023 6:53 am

Thanks, Yabby, you are really exaggerating..I am also a loner with my hobby like you, no real club association (only pay membership fee so that i get the 3rd party liability insurance) and have no-one around to turn to for immediate solutions, so I am trying to improvise..my solutions are not that elegant, but usually work, sooner or later ..

Yabby Mon Jan 30, 2023 2:43 pm

balogh wrote:Thanks, Yabby, you are really exaggerating..I am also a loner with my hobby like you, no real club association (only pay membership fee so that i get the 3rd party liability insurance) and have no-one around to turn to for immediate solutions, so I am trying to improvise..my solutions are not that elegant, but usually work, sooner or later ..

It is a brilliant, pragmatic and simple solution. That is no exageration. The difference is quite significant to my planes, engine mount system and engines I use. I was going to have to change the entire engine mount system on my planes (retro fit) and or change the Cylinders on my engines to slitted cylinders only, or run a round muffler which I didnt want to do. So in the scheme of things to me, the solution is significant. A small thing/idea, easy to make and fit to existing design of planes and engine mounts, made from beer can, makes the whole thing work.

I do not mean to exagerrate, I love that style of thinking and solution. I certainly couldnt and didnt see it. This is the benefit for those of us that fly as loners of having this forum to bring up these things and get peoples thoughts and ideas. It has made me very happy as the problem and what I thought I had to do to resolve it didnt make me happy, and I had thought of a shield but couldnt see how to fit it. I completely ignored the unused side bearer mounts. Perfect.

No exageration intended. Sincere appreciation of a great idea offered. cheers

GaryB
'Yabby'

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