Vector 40 Maiden Flight Problems

[Kafin Noe’man]

Hi all!

Beside rebuilding the crashed Banshee, I have also just finished a Brodak Vector ARF.

I just had the maiden flight for the Vector this weekend, first impression was “Wow! This plane is great!” It flew very smooth and responsive. The line tension was good enough. 

It is powered with:
- ENYA 35XS (with ENYA No. 3 glow plug)
- Muffler is attached, but I set it no muffler pressure
- APC 10.5 x 4.5
- 4.5 oz Magnum Uniflow tank

On the ground, it ran well. I even tried to tilt it both up, down, and even put it inverted without any problems at all.

However, it acted differently when up in the sky. Only after around 5 laps, the engine stopped like it was run out of fuel, but in fact it still had enough amount of fuel in the tank.

It seemed the fuel wasn’t distributed good enough to the venturi when the Vector was flying.

For your information, the tank was sit straight on top of the wooden bearer. I didn’t put any shimming on it. Do I need this?

What’s wrong with my Vector setup? Was the fuel tank too small? Any other ideas or thoughts?

Looking forward to hearing more from you.
Thanks a lot!


Best,
Kafin

[Craig Beswick]

Clean the tank, check fuel lines for any cuts or damage. Do you have an inline fuel filter?

You bench run the engine with a 4+ ounce tank?

If none of that helps then I would put it on pressure.

Craig

[Fred Quedenfeld jr]

Tank has dirt need to flush out many many times

[Kafin Noe’man]

Tank has dirt need to flush out many many times

If this is the case, how do I know whether it’s dirty or clean?
And how do you clean it up? Any tips?

[Paul Taylor]

Can you repeat the problem while flying?
Does the engine speed up and then quit or just shuts off?

The pickup tube on the tank needs to be in line with the venturi.

If the engine just shut off it could be a bad plug. Or you could have trash in your tank.

Always use a fuel filter.

Some things to try.
- flush the tank with acetone.
- hook up a fuel line to the venturi and push fuel through using a syringe.
- check your glow plug.

Also I had this same problem once and a found a piece of solder in the tank that stopped up the fuel pickup.

Good luck.

[Craig Beswick]

In Australia we use methylated spirits to clean tanks because it evaporates quickly. I'm not sure what the guys in the US use or what it would be called in Indonesia.
But, as stated, you need an inline filter.

Craig

[Steve Dwyer]

Use Naphtha to clean the tank if in the airplane it will not affect the finish, if the tank has been removed use Acetone. While out, plug the tank and pressurize it, hold it under water and look for leaks. Just had the same issue on my Primary Force 3.5 oz wedge tank. Solder repaired the leaking seam and engine ran fine.

Steve

[Kafin Noe’man]

Can you repeat the problem while flying?
Does the engine speed up and then quit or just shuts off?

The pickup tube on the tank needs to be in line with the venturi.

If the engine just shut off it could be a bad plug. Or you could have trash in your tank.

Always use a fuel filter.

Some things to try.
- flush the tank with acetone.
- hook up a fuel line to the venturi and push fuel through using a syringe.
- check your glow plug.

Also I had this same problem once and a found a piece of solder in the tank that stopped up the fuel pickup.

Good luck.

The engine didn’t speed up at all, in fact it felt like the fuel distribution wasn’t stable throughout the flight. It had the feeling if you’re flying a plane when the fuel is about to run out (I hope you get what I'm trying to say).

The engine and plug are brand-new, it has been broken in well on the ground. So I’m suspecting that it has to do with the fuel system (tank/fuel lines/etc.)

Try cleaning the tank will be worth to try.

Thank you!

[Fred Quedenfeld jr]

remove tank from plane
Fill tank with Acetone
push acetone from tank though line that would hook up to needle valve
Capture fluid in white paper towel or white rag
inspect white surface for signs of dirt
repeat process til rag  comes clean
Fred Q

[Kafin Noe’man]

remove tank from plane
Fill tank with Acetone
push acetone from tank though line that would hook up to needle valve
Capture fluid in white paper towel or white rag
inspect white surface for signs of dirt
repeat process til rag  comes clean
Fred Q

Thank you so much for the details!
I will try it!

[Kafin Noe’man]

Clean the tank, check fuel lines for any cuts or damage. Do you have an inline fuel filter?

You bench run the engine with a 4+ ounce tank?

If none of that helps then I would put it on pressure.

Craig

How significant will using the muffler pressure make a difference?

[Ken Culbertson]

How significant will using the muffler pressure make a difference?

Muffler pressure to your problem is probably not significant.  One question that was asked was did it speed up?  You said it didn't.  It just quit.  Sounds like a glow plug or the fuel itself.  If it didn't speed up it was getting enough fuel.  Quitting without speeding up usually means no ignition which comes from the plug, bad, damaged or flooded.  I had the exact same problem on an OS46LA.   We have an engine guru in our flying group that muttered "bad gas" as he watched me playing with everything else. 

Ken

PS - it could also be a combination of things so cleaning the tank never hurts.  I use trained ants with tiny flashlights to inspect.

Plugs are a crap shoot.  There are good ones and bad ones in every batch.  Some last forever some get trashed immediately.  Always have two you can trust.  When I was flying a lot and using IC I would fly a new plug till I was convinced it was good then take it out, store it in my box and test another new one.  That way I always had a "go to" plug to use.  This was before they cost a gazillion $....each

[Tim Wescott]

When you're ground testing, you should be able to run out a tank with the outboard wing pointed down -- this simulates the g forces on the plane when it's flying.  On a typical rigid uniflow tank, with the plane purely upright or inverted you can run through about half a tank, then the pickup gets uncovered and the engine runs out of fuel.

If that's the test you did -- great.

Another thing that's consistent with what you're seeing is a pinhole leak or a crack in a fuel line, or a loose fit to the spraybar.  Sometimes you'll cut a slash into the fuel line when you push it onto the tank or the spraybar or things can just be loose -- it can run just fine on the ground (or upright), but when the plane experiences the extra g forces of flight (or in one case when I was a beginner, every time I went inverted) a hole opens up and the fuel system draws air instead of fuel.

While you're doing everything else -- check that the fuel lines are good, and make sure that they fit tight onto any tank fittings, the spraybar nipple, and the nipples on the fuel filter if you have one.  To check the lines, take them off the plane, then inspect them visually.  Stretch them to look for holes opening up, and bend the ends where they go onto the tank fittings to see if a gap opens up.  It's hard to say what's right as far as tightness on the nipple goes, but it should take a good healthy tug to get the line off -- if it doesn't, then you need smaller tubing there (or, if you can't get smaller tubing where you are, twist some fine wire around it as a hose clamp -- this is a last resort; I'd do that then start looking for the next size down tubing).

[Steve Dwyer]

I'm not an ENYA owner but I found in SH some past comments about the need to properly break in a new engine. Recommendation say it should be bench run 45 minutes in a wet 2 cycle and then fly it, otherwise they tend to run for a short time then quit as has yours. Also they need about 22% castor oil but no more, the modern RC synthetic oils may be a problem. It could be you're overheating a new engine and it needs to be broken in.

Steve

[Dan McEntee]

How much fuel did you put on board? Do you have the fill, overflow, and engine pick up lines plumbed correctly. Make sure the tank is secure and not sliding around and pinching the fuel feed off.
 Type at you later,
   Dan McEntee

[Kafin Noe’man]

How much fuel did you put on board? Do you have the fill, overflow, and engine pick up lines plumbed correctly. Make sure the tank is secure and not sliding around and pinching the fuel feed off.
 Type at you later,
   Dan McEntee

I put around 4.5 oz to the tank. And I plumbed correctly.
The tank was secured and not moving at all.

[Paul Taylor]

The engine didn’t speed up at all, in fact it felt like the fuel distribution wasn’t stable throughout the flight. It had the feeling if you’re flying a plane when the fuel is about to run out (I hope you get what I'm trying to say).

So it sounds like the engine was surging. Correct?
If so you have a fuel delivery problem not a bad plug. IMHO

- check for pin holes in fuel lines or tank.
- trash in tank or NVA

Use a fuel filter of some type.

[Ken Culbertson]

So it sounds like the engine was surging. Correct?
If so you have a fuel delivery problem not a bad plug. IMHO

- check for pin holes in fuel lines or tank.
- trash in tank or NVA

Use a fuel filter of some type.

This is new information.  Surging indeed would indicate fuel delivery vs ignition.  Improper break-in, as mentioned earlier would lead to a smooth short run and an abrupt stop but not surging.  I wish we could hear exactly what it sounded like when it quit.  Fuel starvation would lead to a brief leaning out right as it quit.  Coupled with a bad plug it might not lean out.  This might also change my position on muffler pressure.  If the tank and fuel lines were in perfect condition but the venturi/spray-bar combination were on the verge of not drawing enough fuel it might act like this in which case muffler pressure would help.
So would a different venturi. 

Ken

A side note.  Somewhere in the late 70's I was in my peak of proficiency.  At a regional contest my trusty OS35s quit abruptly in the overhead 8 of the 1st round.  I checked nearly everything I could and put in a practice flight during the lunch break without incident.  In the second round it quit in the vertical 8.  It turned out to be the one thing I didn't thoroughly check - the fuel.  Something had contaminated my fuel with little flakes.  Blowing out the fuel filter worked for 1 flight.  Never used one again.  Since then, I filter it as I fill the tank instead.  If you use a filter, use one that you can see if it is clogged. Also they are a big source of air leaks.  IMHO the shortest, unobstructed path from the tank to the venturi is the best.   Others swear by filters, I swear at them!    

[Steve Dwyer]

Kafin,
Don't see anything here about the type or age of the fuel you are using. Old fuel stored in plastic jugs supposedly will drop the nitro % as it can escape through the thin plastic wall. A low nitro level can result in a hotter running engine especially this time of year. Also the lower pitch prop you are using will unload the engine increasing the RPMs and cause it to run hotter. Why not use a 10 x 6 on this 35? I'm leaning toward a fuel quality issue.
Steve

[Doug Moisuk]

Check the tank for leaks. Some of the new tanks are very bD for leaks.

[Air Ministry .]

For some reason , if you flush a new tank , then use fuel to flush it again , it seems to work .
If you dont , it seems to wait till it has effectively , before it does .


So a untried tank may well need to settle in . ALSO it could be a V I B E problem . I use the black foam in some meat packs as shims .
As its firm but might absorb a bit of shaking .

[John Park]

I'm not an ENYA owner but I found in SH some past comments about the need to properly break in a new engine. Recommendation say it should be bench run 45 minutes in a wet 2 cycle and then fly it, otherwise they tend to run for a short time then quit as has yours. Also they need about 22% castor oil but no more, the modern RC synthetic oils may be a problem. It could be you're overheating a new engine and it needs to be broken in.

Steve

I had exactly this experience many years ago with PAW 2.5cc and .19 diesels - fresh out of the box, they would generally bench-run OK, but try to fly them too soon and they would simply cut dead after a couple of minutes in the air.  It's a long time since I've owned an Enya, but I seem to recall that a .29-III I had was just the same - needed an unusually long period of running in.  After that, though, and just like the PAWs, it seemed to get better and better the more you flew it. My guess is: there's nothing wrong with the engine or fuel feed, it just needs more running.

[Kafin Noe’man]

Thank you all for your responses!

Additional information, the engine is a brand new, so is the glow plug. The tank is also new.

Having read all your suggestions, my next step would be:
1. Cleaning the fuel tank with acetone. It won’t hurt doing this.
2. Checking for any leaks in the tank.
3. Rechecking and reworking the fuel lines, and adding in-line filter. I’d probably get new fuel lines installed.
4. Installing some vibration ’absorber’ — need more suggestions on this, would be better if I can see photos.
5. Flying with muffler pressure.

I hope my problem is like to what John said, it’s the engine that needs more running.

I had exactly this experience many years ago with PAW 2.5cc and .19 diesels - fresh out of the box, they would generally bench-run OK, but try to fly them too soon and they would simply cut dead after a couple of minutes in the air.  It's a long time since I've owned an Enya, but I seem to recall that a .29-III I had was just the same - needed an unusually long period of running in.  After that, though, and just like the PAWs, it seemed to get better and better the more you flew it. My guess is: there's nothing wrong with the engine or fuel feed, it just needs more running.

Cheers!

[Ken Culbertson]

Proper break-in after the bench sessions means running a "wet" 4 cycle till it can run out the tank in the air and not go lean except right at the end.  Only then can you start ramping it up slowly.  If you need muffler pressure to keep it running then you have other issues.  Pressure is to keep the flow constant, not to simply make it work.  I would add the pressure after you have it thoroughly broken in and cured the surging if you still think you need it.  I don't quarrel with using an inline filter, just pick one you can see through and not have to take apart to clean.  One of the biggest causes of fuel line air leakage is constantly taking it on and off.

I learned a simple field test for leaks.  Take off the cowl and flip it over slightly nose up so you can see the fuel line.  Cover the venturi with a finger and draw the fuel up to the needle then hold it there still covering the venturi.  If the fuel quickly drains back to the tank or you are unable to draw the fuel up to the venturi easily then you probably have a leak.

Good luck - As you have probably noticed, you have an issue with multiple causes and multiple cures.  That is what makes this hobby so wonderful.

Ken

[Paul Taylor]

vibration ’absorber’

Any material that will dampen vibration. I have used old mouse pads cut to the size of the tank on profiles.
On a full fuse your limited due to keeping the pickup in line with the NVA. A thin piece of rubber or packing foam.  Just make sure your tank is secure and not bouncing around in the tank box.

Be sure to check your tank for leaks. I have seen new tanks leak. It’s easy to do. Plug all vents but hook your syringe to one vent. Hold it under a bucket of water and add pressure to the tank. You should feel it puff up a little. Look for bubbles.

Keep us updated as to what worked. Your headed in the right direction I think.
Good luck.

[Steve Dwyer]

The subject of pads beneath the tank on a profile to reduce vibration has often been discussed. From what I have read vibration isolators can have benefits depending on the application. The type of vibration (frequency), the application and loading of a pad it's thickness and type material play into determining the pad's effectiveness.  Vibrational forces are dampened (reduced) when the pad absorbs the vibration preventing it from being transmitted into the adjacent surface. A thin pad skin that is crushed under an object or tank will absorb little vibration and tends to just allow the forces to be transferred into the tank with little benefit.

A while back for the fun of it I stuck my Fox Combat 35 on the nose of my Tudor and couldn't keep it running on a standard vented tank. Following recommendations I placed 1/8" rubber pad under the tank with little results. The Fox was vibrating too much and the tank was foaming. It's wasn't the prop, there just wasn't enough mass in the nose of the fuse to absorb the narley Fox's vibrations. A couple drops of defoamer (WD40) in the fuel and it ran fine. Today I don't use vib pads except when I want to fill the space behind to better secure a tank. Vib pads may be of some benefit in a modern smoother running ABC engine but on an older ENYA I'd question the effectiveness.

Steve

[Steve Helmick]

What is the design/construction of this ENYA 35XS? AAC or ABC piston/cylinder? Baffled piston or flat top, ball bearing or sleeve bearing on the shaft?

It's been years since we had an Enya importer in the USA...as far as I know...so keeping track of newer products isn't so easy. They have a VERY good reputation, but the marketing has been lacking, IMO.

Clean the tank. I see you're using a UNIFLOW tank. They typically need to be set higher than a non-uniflow tank, i.e., above the spraybar by maybe 1/4" or 6mm or even more. I can't say that I understand why. If you are NOT capping off the overflow vent, then the tank is NOT working as a UNIFLOW tank. Cleaning the tank might be the most critical thing...and checking for leaks.

I personally witnessed Ted Fancher's flight where the engine swallowed a honey bee and stopped the engine. It happened quickly if I recall it correctly, but Ted or Brett might have a different recollection. So, I'd say you might consider adding a layer of nylon mesh over the venturi opening (o-ring to fasten it on), after checking to see that the venturi bore is clear of large bug carcasses.

I'm a believer in having a fuel filter in the feed line...Sullivan "Crap Trap" is my preference, and I usually inspect, clean, or replace them each Spring, before our flying starts...along with (maybe) a new glowplug. I don't know what sort of glowplugs Ken used, but I've never had a problem with Thunderbolt, K&B, or the few OS glowplugs that came from the factory with some of my OS LA series engines. I also like muffler pressure, mainly to have a closed system that keeps tiny bugs and seeds out of my fuel tank and filter. It is then VERY important to make sure your muffler doesn't come loose or fall apart, because the engine will then go dead lean. A good alternate is to use an air filter on the uniflow vent. This can be done by modifying a small fuel filter and a short piece of fuel hose.

My preference is to set the NV after warming up the engine, every flight, and I do that by pinching off the pressure line while watching the tachometer. When the engine is up to temperature, the rpm returns to the same number two or three times in a row...that's assuming the engine is on the rich side of peaked. If it's already too lean, then it will stop or just get slower. I see a lot of guys start the engine, immediately set the NV and about the time they pick up the handle, the engine goes rich...they hesitate...sometimes the launcher cranks in the NV a 1/2 turn, and the setting is WRONG! Don't be that guy!    Steve

[Ken Culbertson]

I don't know what sort of glowplugs Ken used -

Mostly Hot Shielded that were, I think, Fox & K&B.   There was another one, I think it was Fireball or something like that.  Had bad luck with OS plugs.  That was a long time ago.  My point was that you don't know for sure that a new plug is good till you use it.  I have had to throw out quite a few over the years.  We all know that plugs never go bad at a contest, but if one does, you have a known good one in your box.  Not my idea, that came from one of our 70's elites. The Sullivan "Clap Trap" is the only filter I will use but like I said, I stopped using them when one cost me a contest win.  It was not a Sullivan.

The rest of your post makes sense.  We have an engine guru here and he does pretty much what you suggest.  Runs his motor up about 15 seconds when he gets to the field then, after starting it for a flight he slowly takes all of his stuff back to the edge of the circle then starts setting the needle valve with his Tac.  Sucks if you are holding for him but he almost never gets a bad run.  Now they tell me....  I was always a flip & fly and I had quite a few times when it did just what you described going rich just as I got to the handle.

Ken

[Steve Dwyer]

Steve

"My preference is to set the NV after warming up the engine, every flight, and I do that by pinching off the pressure line while watching the tachometer. When the engine is up to temperature, the rpm returns to the same number two or three times in a row...that's assuming the engine is on the rich side of peaked. If it's already too lean, then it will stop or just get slower."

Interesting, the importance to run a warm engine. What I find on my OS FP 35s and 40s they tend to go lean immediately upon flying. I run Uniflows on most planes and wonder what causes the leaning that occurs. I have used the fabric/o ring restriction and I keep track of take off rpms but no matter the effort to find a comfortable lap time the engine wants to run away. I wonder if "negative head" affect on the fuel from the forward motion increases the work on the venturi resulting in a reduced flow rate. It would seem a pressurized tank would help offset this. 

Your shoughts?

Steve

[Steve Helmick]

Um, yeah, Fox and Fireball glowplugs would be a problem. Which are the ones Brett "dislikes"? Rossi?

I've only used a few OS A3 glowplugs...they came with various LA series engines. No problems, but very small sample. The thing that kinda bothers me about OS glowplugs is that at least some are made in only one metric length, which is sort of "medium". Not sure if Enya does the same or not, but it seems to me that OS is trying to increase the sales of their glowplugs by designing their engines to only fit OS glowplugs...and maybe charging quite a lot for them. Short glowplugs in engines designed for long glowplugs isn't a good thing, for sure, so I'm not too keen on "medium" length plugs.

Never had any sort of bad stuff happen with Thunderbolt glowplugs, but I stocked up when they were from Hobby People, and still have lots of new ones in stock. They were made by Ohlsson Corp., as were K&B glowplugs. It seems likely that RJL/Mecoa/K&B glowplugs are still made by Ohlsson Corp. AFAIK, I've never seen a Merlin glowplug and don't know if they're still being produced. Harry Roe made them and they were sold by Brodak, but we just never see them here on the Left Coast. I've read good things about them, however, and remember Harry Roe's name from my days of speed flying in the middle '60's. Sad when he passed on.  Steve

[Steve Helmick]

Steve

"My preference is to set the NV after warming up the engine, every flight, and I do that by pinching off the pressure line while watching the tachometer. When the engine is up to temperature, the rpm returns to the same number two or three times in a row...that's assuming the engine is on the rich side of peaked. If it's already too lean, then it will stop or just get slower."

Interesting, the importance to run a warm engine. What I find on my OS FP 35s and 40s they tend to go lean immediately upon flying. I run Uniflows on most planes and wonder what causes the leaning that occurs. I have used the fabric/o ring restriction and I keep track of take off rpms but no matter the effort to find a comfortable lap time the engine wants to run away. I wonder if "negative head" affect on the fuel from the forward motion increases the work on the venturi resulting in a reduced flow rate. It would seem a pressurized tank would help offset this. 

Your shoughts?

Steve

It appears to me (77 years old, running glow engines for many decades), that the NV setting changes from cold start to running temperature, so it makes sense to set the NV when the engine has reached a stable running temp. Also note that if you fly a flight in the early AM and then again mid-afternoon, the NV will need adjusting again, for the air temp has likely changed considerably. This can cause a problem with fuel consumption and run time, of course.

I've never flown a .35FP or .40FP, but generally, the .35FP is supposed to be better because the cylinder liner is thicker. Yet, the .46LA is the pick of the .40/.46LA, and the liner is very thin IMO. The FP's are not happy with too much prop load or too much pitch. It happens that I have a .40FP and a .25FP, but have not personally run either.

It seems to me like approximately 4" pitch would be required, but I'd be very tempted to only use them for OTS or Sport flying, where you either want the plane to go faster than a PA plane, or at least can tolerate it flying faster (sport flying). Have you tried a 10-4 APC or 10.5 x 4.5 APC? APC props vary widely in design, but even the ones that don't look like stunt props still work very well. Mysterious!  Steve 

[Steve Dwyer]

Steve,

I typically run a 11x4 APC on the FP 40s and have found a smaller prop will slow it down a bit but then the lost power affects on corners especially in OTS and sport flying comes into play. I have tried adding a head shim and reducing the NVA net opening area by changing out the needle valve/venturi combination but I still see the runaway I'd like to get away from. Even with a pressure system I still think the fuel head affect would cause the leaning during flying. This issue of runaway has been an old discussion topic but I don't recall a solution. I have to believe someone here has some ideas as well.

Steve

[kevin king]

I'm not a super expert, but for more line tension check your line length. usually measured from the center of the handle to  the center of your airplane. It should be 60 feet. Also check your lap times, should be around 5.2 or  5.3 seconds. Moving your adjustable  leadouts back an 1/8 of an inch will also increase line tension, as will adding nose weight to get the CG further forward. Experts please feel free to correct me. Enjoy the Vector Kafin. Looking forward to finishing mine.

Kevin.

[Kafin Noe’man]

Can bubbles in the fuel line be the problem for the surging?
And how do you fill the tank without causing bubbles inside the fuel lines?

[Ken Culbertson]

Can bubbles in the fuel line be the problem for the surging?
And how do you fill the tank without causing bubbles inside the fuel lines?

It is unlikely that they are being caused by filling.  An air leak or vibration is more likely and yes, they can cause surging.

ken

[Steve Dwyer]

Have you leak tested the tank underwater? It's a long shot but possibly the internal tank plumbing is built incorrectly or aligned wrong. You could try another tank. When running it can you see bubbles coming directly out of the tank when tilting the plane so the internal pick up is at the bottom submerged outside corner? Are the bubbles showing directly out of the tank or only at the venturi inlet? Try draining the tank and place a couple drops of WD-40 in the fuel and try running it again. Once the tank can be eliminated return to the engine for another bench run.  A video would be helpful.....If still no luck send the model back to Brodak for a refund-----JUST KIDDING.

Steve

[Kafin Noe’man]

Have you leak tested the tank underwater? It's a long shot but possibly the internal tank plumbing is built incorrectly or aligned wrong. You could try another tank. When running it can you see bubbles coming directly out of the tank when tilting the plane so the internal pick up is at the bottom submerged outside corner? Are the bubbles showing directly out of the tank or only at the venturi inlet? Try draining the tank and place a couple drops of WD-40 in the fuel and try running it again. Once the tank can be eliminated return to the engine for another bench run.  A video would be helpful.....If still no luck send the model back to Brodak for a refund-----JUST KIDDING.

Steve

The tank has no leak, I tested it yesterday.
Will try again tomorrow with some adjustments based on your suggestions.

If it still doesn’t work, I’ll go back to Brodak, look for electric conversion 

[Ken Culbertson]

It is unlikely that they are being caused by filling.  An air leak or vibration is more likely and yes, they can cause surging.

ken

I quoted myself because there is an exception.  If you are using one of those ancient orange bulbs and it empties before the tank is full it will pump air into the tank and probably make some foam.  Use a pump or clear hypodermic syringe that has more fuel in it than what you are putting in the plane.

Ken

[Ken Culbertson]

If it still doesn’t work, I’ll go back to Brodak, look for electric conversion 

Now you are talking!

Ken

[Reptoid]

Lots of jumping to conclusions and guessing.......My guess; too lean at launch

[kevin king]

Try using a different batch of fuel, or read this:

https://stunthanger.com/smf/engine-set-up-tips/fuel-glo-plug-and-running-tips/

[Motorman]

Sometimes they make the tank with the vent tube too close to the pick up tube. This causes all kinds of problems. If you can't fix it some other way, consider poping the rear end cap off the tank and having a look at the plumbing. I separate my tubes by 2" on a 4oz (4") tank.

Motorman

[Kafin Noe’man]

Update:

Last weekend, I did more engine break-in and experimented on trying different tanks.
Voila! The magnum tank I had was the main problem. The fuel delivery was much better when I tried the RC plastic clunk tank. Will do some more break-in and making sure this tank system delivers constant fuel to the engine.

Thank you guys 🙏🏻

[Ken Culbertson]

Update:

Last weekend, I did more engine break-in and experimented on trying different tanks.
Voila! The magnum tank I had was the main problem. The fuel delivery was much better when I tried the RC plastic clunk tank. Will do some more break-in and making sure this tank system delivers constant fuel to the engine.

Thank you guys 🙏🏻

That is all I have uses since 1975. Internal, profile, doesn't matter.  Clunks are best.  Some will disagree.

Ken

[John Carrodus]

Well done Kafin. I remember reading here in SH years ago that 90% of engine problems are fuel tank or line issues. There are sooooo many factors at play in just this one vital aspect of CL flying! Hey, if it was easy we'd soon get bored! Plastic clunks are pretty good, you can see problems and sort em out pronto.