Interested In Suggestions For A Tank For A Profile

[Andre Ming]

I'm tired of false starts and red-herrings. I've chased issues until I'm blue in the face. None of my fuel is going to work with sport flying 35 sized engines, and my tanks are suspect. The engine pictured will run okay and take a needle setting on the clunk tank equipped test stand. Unfortunately, the Sig 25% nitro fuel gives me about 1 - 2 runs before it distorts the glow plug element. Plus, trying to set a needle once mounted on the airplane w/tank pictured is a lesson in frustration. (Won't richen enough.)

I'm going to place an order with Brodak for two quarts of 10% nitro fuel AND a new hard tank for the profile Flite Streak.

There is ample room between the leading edge and the back of the engine for a tank 2 3/4" in length. (Which will leave about 1/4" clearance.) See the pic.

This is too good of an airplane to keep getting sidelined by issues I seem to be creating for myself.

I would covet your opinions/suggestions on a tank.

Thanks.

Andre

[pat king]

I never had any luck with that shape tank. When the full the fuel level was so far above the spray bar that it flooded the engine when trying to start it. I had it on a Ringmaster because it is short for the capacity. That helps on short frontend airplanes, but I never had any luck with it.

Pat

[Colin McRae]

Andre

Most of my fuel tanks are from Brodak. Good quality and no issues to date.

One additional problem I see with your tank set up is that the vent and overflow are straight up and down. Sometimes this can result in a slightly negative pressure in the tank when air passes over the vent/overflow affecting good fuel flow to the engine. 

On a profile model, I have been using Brodak's oval profile uniflow tank. The other option is a wide wedge uniflow. But for the same volume, the oval profile design is a bit shorter and has fit better on some of my models that have limited space for the tank.

But be aware that the Brodak 'stock' oval profile tank has the fuel pickup on the top of the tank. Not the best location for efficient the short fuel tubing run to the engine in my opinion. If you ask them, Brodak will custom modify the oval tank to relocate the fuel pickup to the bottom. The pic I have attached is just such a tank that Brodak made up for me. As you can see, the fuel line goes directly to the spray bar under the engine, nice and short. If I remember correctly, Brodak charged me like $3 extra for the modification. And all tubes should face forward for best in-fight results. When facing forward, prop wash ram air at the vent acts to provide a slight positive pressure in the tank enhancing fuel flow.

The Brodak stock wide wedge uniflow tank is OK as is because the fuel pickup is already on the bottom of the tank. But the wide wedge uniflow tank is longer.

Also on a Fox 35 application, my experience is to have the centerline of the tank around 1/4" to 5/16" above the centerline of the engine for improved inverted lap times. Same thing for my Enya 29.

[Colin McRae]

One other trick some use on tanks that have straight up/down vent and overflow is to add a short piece of fuel tubing cut at a 45 deg angle and facing forward. Helps ram air during flight to slightly pressurize the tank enhancing fuel flow.

[Dave_Trible]

Colin the first tank you show is indeed a uniflow.  The second with two open vents is suction, not uniflow.  Those we used in the 'old' days before someone came up with the uniflow concept.  Their fault is as they drain out fuel during the flight the minimal head pressure dies off and the engine gets progressively leaner until it may be in a full scream by the end of the run.  Uniflow adds pressure during the run to make up for the emptying tank.  I'd always suggest uniflow,  if even just to prolong engine life.

Dave

[Andre Ming]

Very much appreciate your input, Pat and Colin. EDIT: And you, too, Dave. (Just saw your post.)


Here's my options at Brodak that will fit the space I have:

1.  https://brodak.com/fuel/oval-profile-uniflow-fuel-tank-3.html

2.  https://brodak.com/fuel/oval-profile-standard-vent-fuel-tank-3-1-2-oz.html

3.  https://brodak.com/fuel/wide-wedge-uniflow-fuel-tank-2.html

4.  https://brodak.com/fuel/standard-vent-wide-wedge-fuel-tank-2.html

5.  https://brodak.com/fuel/wedge-fuel-tank-2-1-3-oz-1.html

6.  https://brodak.com/fuel/standard-vent-medium-wedge-fuel-tank-2-oz.html

7.  https://brodak.com/fuel/square-wedge-chicken-hopper-fuel-tank-3.html

I have a GRW Chicken Hopper that I recall was less than satisfactory in performance, so unless compelling evidence/testement in favor of a Brodak Chicken Hopper, I'm shying away from the Chicken Hopper concept.

Which of the above would you go with and why?

Sorry for being such a bother, but I truly have very little experience with hard tanks. I've been almost exclusively bladder pressure for 50+ years.


Andre

[Colin McRae]

Colin the first tank you show is indeed a uniflow.  The second with two open vents is suction, not uniflow.  Those we used in the 'old' days before someone came up with the uniflow concept.  Their fault is as they drain out fuel during the flight the minimal head pressure dies off and the engine gets progressively leaner until it may be in a full scream by the end of the run.  Uniflow adds pressure during the run to make up for the emptying tank.  I'd always suggest uniflow,  if even just to prolong engine life.

Dave

Dave, I realize the tank is not uniflow, but a standard vent tank. It was just to show Andre that 45 deg tubing can be added to straight vents to help with fuel draw.

[Colin McRae]

Very much appreciate your input, Pat and Colin. EDIT: And you, too, Dave. (Just saw your post.)


Here's my options at Brodak that will fit the space I have:

1.  https://brodak.com/fuel/oval-profile-uniflow-fuel-tank-3.html

2.  https://brodak.com/fuel/oval-profile-standard-vent-fuel-tank-3-1-2-oz.html

3.  https://brodak.com/fuel/wide-wedge-uniflow-fuel-tank-2.html

4.  https://brodak.com/fuel/standard-vent-wide-wedge-fuel-tank-2.html

5.  https://brodak.com/fuel/wedge-fuel-tank-2-1-3-oz-1.html

6.  https://brodak.com/fuel/standard-vent-medium-wedge-fuel-tank-2-oz.html

7.  https://brodak.com/fuel/square-wedge-chicken-hopper-fuel-tank-3.html

I have a GRW Chicken Hopper that I recall was less than satisfactory in performance, so unless compelling evidence/testement in favor of a Brodak Chicken Hopper, I'm shying away from the Chicken Hopper concept.

Which of the above would you go with and why?

Sorry for being such a bother, but I truly have very little experience with hard tanks. I've been almost exclusively bladder pressure for 50+ years.


Andre

My opinion.

Whatever tank you choose, I suggest that a uniflow design be used, and not a standard vent tank. On a standard vent tank design, the engine speed will change throughout the flight as the fuel level drops (gets leaner and leaner as the flight progresses). But a uniflow design tank maintains the engine speed throughout the flight. A more consistent engine run.

I have a Brodak oval profile uniflow 3 oz tank on a Ringmaster with Fox 35 Stunt engine. But my tank was one that was modified by Brodak to relocate the fuel pickup tube to the bottom of the tank. The setup runs quite well (except for the usual Fox 35 Stunt 'death burp' when going inverted). Also notice that my tank is mounted around 5/16" above the center of the engine.

If you just want to go w/ a stock Brodak tank, then go with the wide wedge uniflow design.

Also, on any uniflow tank, the overflow tube needs to be plugged off during flight.

[Andre Ming]

Colin:

Thanks for additional input.

What do you feel are the advantages to a bottom outlet?

Andre

[Colin McRae]

Colin:

Thanks for additional input.

What do you feel are the advantages to a bottom outlet?

Andre

Andre

This is a pic of the Brodak stock oval profile uniflow tank. The tube on the top outside is the fuel pickup tube. If you picture your profile model, the fuel tube has to transition to go under the engine to the spray bar inlet. Anytime fuel tubing goes up and down (i.e.: and has high points), air bubbles can accumulate causing possible issues. It is always a good design to have the shortest possible tubing runs that don't go up and down. On my Ringmaster example, the fuel tubing on the bottom of the tank is a straight shot route to the engine fuel inlet, nice and short.

The fuel pickup on the top may work ok as long as there are NO leaks anywhere in the fuel supply system. And when you are trying to start your engine, it might be cumbersome due to air bubbles that collect at the tubing high points.

Maybe just get a wide wedge uniflow tank (if it will fit on your model) where the fuel pickup is already on the bottom side of the tank.

[Dennis Leonhardi]

Colin:

Thanks for additional input.

What do you feel are the advantages to a bottom outlet?

Andre

Andre, if I may provide an answer: shortest path to the spray bar.

Back about a hundred years ago, I purchased several of those Fox .36 engines.  Vibration was an issue for most as I recall - is that part of the problem?

The group I had varied considerably from one to another.  I did find ONE out of perhaps 6 that ran something close to a 4-2-4 with an added head gasket and "stunt" fuel.

Dennis

[Steve Helmick]

1) Uniflow...it's the WAY. Tin tanks can work fine, but the details are important.
2) Bottom feed gives shorter fuel line from tank to NV, a plus. Mostly for ease of starting, IMO.
3) Use a filter between tank and NV. I like the Sullivan Crap Trap "medium" size. Others like other filters. I'm kind of a fan of old fashioned neoprene tubing, which is still available...but I can't remember what supplier has it. Mostly, I use silicon fuel tube, though.
4) Are you totally committed to using Fox glowplugs for some reason? IMO, they're not very good, and probably the worst made in USA. Ohlsson Corp. (leftovers of O&R split) makes the best glowplugs in the USA, if not the World. Thunderbolt plugs are made by them. K&B plugs were, but I wouldn't state that they still are...but probably. Enya and OS glowplugs are fine, but $$$.
5) Since we're using Uniflow, I like muffler pressure. Not everybody does, and not everybody should. If your muffler tends to come loose, don't use muffler pressure, and for sure don't use a muffler gasket. I like muffler pressure because it eliminates the tiny seeds and bugs I used to find in my fuel filter. Some are worried about the exhaust residue collecting in the muffler and clogging it. Don't worry about that, it just doesn't happen. If your muffler gets clogged (they can), that isn't why. If it does, crockpot in antifreeze for 24 hours and rise well in dish soap/water.
6) I expect you're using fuel with 25% castor oil, so I won't go there, and the engine is run-in.
7) Not sure what sort of speed you're expecting (i.e., run type), but vibration & fuel foaming is a real problem with engines that vibrate as much as most Foxes. The reason I mention it is because you've never had that problem with bladder tanks. It appears that you have the rear of the tank kicked outboard to get a clean shut down; that's good!

That's all I can think of. Of the Brodak tanks you listed, I'd just get the uniflow wide (Veco type) wedge. Let the Uniflow work for you. Remember that if you don't cap off the overflow tube, the tank will then run exactly the same as the non-uniflow version, EXCEPT that you need to raise the tank above centerline more with Uniflow than 'standard' double vents. I'm not sure anybody knows why, but speculation is it's due to engine ports usually not being symetrical.  Steve

[john e. holliday]

My self I would have made sure every thing was clean and dry and mixed some J-B Weld to fix the leak.  The was no problem until you cleaned every thing.  I also would have just cleaned the fuel filter.  DidN't I have one on the plane.   But as you have found out fresh fuel cures a lot of problems as well as a good starting battery.  Hope you get it figured out and flying.

[Andre Ming]

Thanks for more input guys!


Colin:

Thanks for the pic. Which is the fuel delivery tube?


Dennis:

Gotcha: Try to make the shortest path to the spray bar. With bladder pressure, I would make an "S" from the bladder tube to the spray bar by running the fuel line between the LE and the rear of the engine. Helped hold the line in place, and with bladder, fuel draw bubbles weren't an issue.


Steve:

Fox plugs - I have a ton of the them. Plus, with open venturi Fox 36X engines on on 10% nitro I get long use out of them without element deformation.

Castor: For the past decades I've used only 10% nitro and castor at around 20%, but that's hard to do now over the counter. My steel vintage liner/meehanite piston Fox engines do well with that, put out good enough RPM/performance for me on combat wings, and plugs last a long time.

You're right, I've run bladder almost exclusively for over 50 years. Foaming wasn't an issue. I may see my Fox engines through a different set of eyes now that I desire a couple of profile planes on suction. Speed? For the sport profiles, faster than a 35 Stunt, but not as fast as a  36/36X at full scream w/restrictor. I was hoping to use that Fox 36 at a fast 4s, but we shall see? Later I hope to build a Fox 35 Stunt powered Magician. For that one I would like the classic Fox 35 Stunt 2-4 break.

The tank kicked to the outside is all John "Doc" Holliday... for he built the airplane and kindly gifted me with it.


Doc:

The tank already had what appeared to be JB Weld on it and was seeping out from under it, I figured it had given up the ghost on me. I originally thought to start clean and fresh... but that ain't workin' out so good as yet!


All:

SO.. I think it's down to one of these two, then?


https://brodak.com/fuel/oval-profile-uniflow-fuel-tank-3.html

https://brodak.com/fuel/wide-wedge-uniflow-fuel-tank-2.html


But WHICH? That is now the decision.

I would prefer to not have Brodak custom anything... that will add time to the order. I'll just need to make do with one of the above.

Andre

[Steve Helmick]

Well, if you're ordering fuel AND a tank, they'll probably be shipped separately, so one will arrive sooner than the other anyway. If the porch pirates get either, then you're hosed.

If you're wondering, I've been told that if you try to run a stunt sized venturi on a bladder pressure tank, it won't work. I think it was Howard who said that, but I don't know why it wouldn't, and I haven't personally tried it.

Looking at the picture of the profile Doc gave you, the nose looks like it might not be as rigid as it once was...could you install a good solid gusset from LE to engine location, about 4" x 4" or bigger, to stiffen it up? I would probably use 1/2" balsa with the grain along the hypotenuse, maybe with 1/32 or 1/64 ply or fiberglass & epoxy top & bottom. As is often said, stiffer is almost always better.   Steve

[Andre Ming]

Well, if you're ordering fuel AND a tank, they'll probably be shipped separately, so one will arrive sooner than the other anyway. If the porch pirates get either, then you're hosed.

If you're wondering, I've been told that if you try to run a stunt sized venturi on a bladder pressure tank, it won't work. I think it was Howard who said that, but I don't know why it wouldn't, and I haven't personally tried it.

Looking at the picture of the profile Doc gave you, the nose looks like it might not be as rigid as it once was...could you install a good solid gusset from LE to engine location, about 4" x 4" or bigger, to stiffen it up? I would probably use 1/2" balsa with the grain along the hypotenuse, maybe with 1/32 or 1/64 ply or fiberglass & epoxy top & bottom. As is often said, stiffer is almost always better.   Steve

Thanks for the follow up, Steve.

Thus far, no Porch Pirates in my neighborhood. However, you never know.

As for the bladders on a smaller venturi: The NVA MUST shut off flow. i.e Pass the suction test. Otherwise, you'll never be able to adjust down the inflow for the small venturi opening to handle. Also, the finer the threads, the better. I've run Fox 35 Stunts on bladder on Super Slow Combat foamies, but used different NVA's. Also have run bladder on restricted 36X engines to slow them down to get me back into flying.

I've had no issues with smaller/restricted venturi's provided there is a good NVA in the target engine.

However, YMMV.

Andre

[Colin McRae]

Thanks for more input guys!


Colin:

Thanks for the pic. Which is the fuel delivery tube?

On the stock Brodak oval profile uniflow tank, the fuel pickup is top-outside. The uniflow/vent is top inside. The overflow is on the bottom.

On this tank, you would fill through the uniflow/vent tube. If not using muffler pressure, the uniflow/vent is uncapped during flight, and the overflow is capped during flight. If using muffler pressure, after filling the tank, the tube from the muffler is connected to the uniflow/vent.

FYI, this shows the tubing arrangement for all the stock tanks that Brodak sells.

Dennis:

Gotcha: Try to make the shortest path to the spray bar. With bladder pressure, I would make an "S" from the bladder tube to the spray bar by running the fuel line between the LE and the rear of the engine. Helped hold the line in place, and with bladder, fuel draw bubbles weren't an issue.


Steve:

Fox plugs - I have a ton of the them. Plus, with open venturi Fox 36X engines on on 10% nitro I get long use out of them without element deformation.

Castor: For the past decades I've used only 10% nitro and castor at around 20%, but that's hard to do now over the counter. My steel vintage liner/meehanite piston Fox engines do well with that, put out good enough RPM/performance for me on combat wings, and plugs last a long time.

You're right, I've run bladder almost exclusively for over 50 years. Foaming wasn't an issue. I may see my Fox engines through a different set of eyes now that I desire a couple of profile planes on suction. Speed? For the sport profiles, faster than a 35 Stunt, but not as fast as a  36/36X at full scream w/restrictor. I was hoping to use that Fox 36 at a fast 4s, but we shall see? Later I hope to build a Fox 35 Stunt powered Magician. For that one I would like the classic Fox 35 Stunt 2-4 break.

The tank kicked to the outside is all John "Doc" Holliday... for he built the airplane and kindly gifted me with it.


Doc:

The tank already had what appeared to be JB Weld on it and was seeping out from under it, I figured it had given up the ghost on me. I originally thought to start clean and fresh... but that ain't workin' out so good as yet!


All:

SO.. I think it's down to one of these two, then?


https://brodak.com/fuel/oval-profile-uniflow-fuel-tank-3.html

https://brodak.com/fuel/wide-wedge-uniflow-fuel-tank-2.html


But WHICH? That is now the decision.

I would prefer to not have Brodak custom anything... that will add time to the order. I'll just need to make do with one of the above.

Andre

[Colin McRae]

If you don't want a custom tank, then the wide wedge uniflow is the way to go. It will work fine.

(But also make sure it will fit on your model)

[Colin McRae]

1) Uniflow...it's the WAY. Tin tanks can work fine, but the details are important.
2) Bottom feed gives shorter fuel line from tank to NV, a plus. Mostly for ease of starting, IMO.
3) Use a filter between tank and NV. I like the Sullivan Crap Trap "medium" size. Others like other filters. I'm kind of a fan of old fashioned neoprene tubing, which is still available...but I can't remember what supplier has it. Mostly, I use silicon fuel tube, though.
4) Are you totally committed to using Fox glowplugs for some reason? IMO, they're not very good, and probably the worst made in USA. Ohlsson Corp. (leftovers of O&R split) makes the best glowplugs in the USA, if not the World. Thunderbolt plugs are made by them. K&B plugs were, but I wouldn't state that they still are...but probably. Enya and OS glowplugs are fine, but $$$.
5) Since we're using Uniflow, I like muffler pressure. Not everybody does, and not everybody should. If your muffler tends to come loose, don't use muffler pressure, and for sure don't use a muffler gasket. I like muffler pressure because it eliminates the tiny seeds and bugs I used to find in my fuel filter. Some are worried about the exhaust residue collecting in the muffler and clogging it. Don't worry about that, it just doesn't happen. If your muffler gets clogged (they can), that isn't why. If it does, crockpot in antifreeze for 24 hours and rise well in dish soap/water.
6) I expect you're using fuel with 25% castor oil, so I won't go there, and the engine is run-in.
7) Not sure what sort of speed you're expecting (i.e., run type), but vibration & fuel foaming is a real problem with engines that vibrate as much as most Foxes. The reason I mention it is because you've never had that problem with bladder tanks. It appears that you have the rear of the tank kicked outboard to get a clean shut down; that's good!

That's all I can think of. Of the Brodak tanks you listed, I'd just get the uniflow wide (Veco type) wedge. Let the Uniflow work for you. Remember that if you don't cap off the overflow tube, the tank will then run exactly the same as the non-uniflow version, EXCEPT that you need to raise the tank above centerline more with Uniflow than 'standard' double vents. I'm not sure anybody knows why, but speculation is it's due to engine ports usually not being symetrical.  Steve

As far as glow plugs go for a Fox 35 Stunt engine using 5-10% nitro and 29% all castor (fuel from Brodak), I have had good success with the Fireball hot long plug from Brodak. At $5 each, I was skeptical at first. But have not had any issues with them. Even if they don't hold up over time, at $5 one could go thru 3-4 of them for the same cost as a single OS plug for instance.

One other thing, the Fireball long 'standard' plug has a med-hot range and I have found that it was not hot enough for 5-10% nitro / 29% castor fuel. But the Fireball hot plug works well on the Fox 35, and any other engine needing a hot-long glow plug.

[Andre Ming]

Thanks everybody for sharing your thoughts and experiences!

I went ahead and ordered one of each of the two uni-flow tanks. I figure I'll experiment and see which of the two perform best for the current combo. There may be another profile sport plane "someday" and I can use the other tank on it.

Also ordered a couple quarts of 10% w/23% 50/50 blended lubricant, some fuel filters, and some other hardware odds and ends.

Now I wait!


Andre

[john e. holliday]

I use J-B Weld when I can't get solder to seal up.  Have never had a problem.  When it held the pressure of 2 ouce shringe I went flying.  I think I had 4 flights on the tank and no problems.  Besides I remember using J-B Weld on car radiators when the would spring a leak.  Never had a problem.

[C.T. Schaefer]

Question.  How big is your venturi. Diameter of spraybar?  For solid fun flying  .270 with a .156 spraybar.  Also. Have not had good luck with Fox plugs lately.  If the rpm drops when the battery comes off you need a different plug.  That Brodak fuel should work ok.   Have Fun!   TS

[Andre Ming]

Question.  How big is your venturi. Diameter of spraybar?  For solid fun flying  .270 with a .156 spraybar.  Also. Have not had good luck with Fox plugs lately.  If the rpm drops when the battery comes off you need a different plug.  That Brodak fuel should work ok.   Have Fun!   TS

Howdy TS!

The Fox 36 in the pic is stone stock, straight from the box. I can't remember the OEM specs for the venturi or spraybar... IF I ever knew that.

Fox "Standard" plugs: A plug per flight back in my modified 36X and 40%+ nitro days. (Of course, that didn't matter back in my Fox Mfg days... I had a factory full of parts free for the using... Duke told me so himself!) Anyway, Duke developed a hi-perf "racing" plug that required a ton of amps to light for ignition, but I never burned one out at any nitro level. I still have a handful of them left from my Fox days, but will never have use for them again. (Forget low nitro, low RPM, use with them: Those plugs were made to scream and need lots of nitro.)

As for recent problems with Fox plugs: I don't think there should be a shelf life for the element... but there could be? Even the newest of Fox plugs are what, 20-25+ years old? I have some that date back to almost to my Fox Mfg years that still glow orange and bright. A few years ago I was given some left over "Heavy Duty" Fox plugs by a fellow Fox Mfg vet and they, too, still glow bright orange.

FWIW: Some more reasons for slow down when the battery lead comes off are ignition issues due to volatility loss in the fuel, or the element has too much resistance (i.e. such as the diameter of the ni-chrome wire) which takes more volatility (hotter combustion temps) to sustain good ignition, as well as mechanical compression issues.

Boy, you really are taxing this old brain of mind. Haven't had need to draw forth engine R&D history in a long time. Nope... my "hot" flying now is one of my stock spec 36X engines on 10% nitro, standard plugs... and just play flying a combat wing while I mentally entertain myself as to how awesome I was. 



erdnA

[Andre Ming]

Wow.

Placed my Brodak order late last night. Just received an email it's been shipped!!

Now THAT's service!

Andre

[Dan McEntee]

Howdy TS!

The Fox 36 in the pic is stone stock, straight from the box. I can't remember the OEM specs for the venturi or spraybar... IF I ever knew that.

Fox "Standard" plugs: A plug per flight back in my modified 36X and 40%+ nitro days. (Of course, that didn't matter back in my Fox Mfg days... I had a factory full of parts free for the using... Duke told me so himself!) Anyway, Duke developed a hi-perf "racing" plug that required a ton of amps to light for ignition, but I never burned one out at any nitro level. I still have a handful of them left from my Fox days, but will never have use for them again. (Forget low nitro, low RPM, use with them: Those plugs were made to scream and need lots of nitro.)

As for recent problems with Fox plugs: I don't think there should be a shelf life for the element... but there could be? Even the newest of Fox plugs are what, 20-25+ years old? I have some that date back to almost to my Fox Mfg years that still glow orange and bright. A few years ago I was given some left over "Heavy Duty" Fox plugs by a fellow Fox Mfg vet and they, too, still glow bright orange.

FWIW: Some more reasons for slow down when the battery lead comes off are ignition issues due to volatility loss in the fuel, or the element has too much resistance (i.e. such as the diameter of the ni-chrome wire) which takes more volatility (hotter combustion temps) to sustain good ignition, as well as mechanical compression issues.

Boy, you really are taxing this old brain of mind. Haven't had need to draw forth engine R&D history in a long time. Nope... my "hot" flying now is one of my stock spec 36X engines on 10% nitro, standard plugs... and just play flying a combat wing while I mentally entertain myself as to how awesome I was. 



erdnA

    Fox plugs are definitely a question mark, if they were produced in the last 10 or 15 years Fox existed. I think those would be the plugs in an orangish type of carboard package. Anything earlier than that has possibilities.  We had a club member show up at Buder with 6 brand new Standard plugs one Sunday, for use in Fox.35 Stunt engine with proper fuel, and they each lasted one flight!! Your stash may be old enough that it predates this, and with not too many other options these days, you might as well try them!! O think these would be the ones in a red, white and blue package or anything else that looks old. Even using "tame" fuel, the compression ratio on some of the older 36X engines may be a plug killer and maybe a head gasket or so will help. Again, a few flight tests will tell the tale.
   Type at you later,
   Dan McEntee

[Doug Moisuk]

I’m a convert to the plastic tank. No problem with winter storage compared to metal. Plus it can be set up for Uniflow if desired. And it can be mounted on the inboard side of a profile fuse if room is an issue.

[Dave_Trible]

Just a for-what-it's-worth on the topic of glow plugs.....The other day I was out to both fly a 'dog' airplane for an upcoming balloon bust thing and to run a new engine on the test stand.  It seemed strange that neither wanted to stay running once the battery was removed.  I tried four different brands and types of plugs and two fuel mixes.   It was cool out-about 50 degrees.  I didn't really get to the bottom of it then but I have since realized all the fuel was kept in the car and it had gotten into the low 40's that night.  I now think the problem might have been the fuel temperature was simply too cold and chilled the engines like liquid coolant as it passed through not allowing adequate combustion temperature to be maintained.  Everyone seemed to be having similar problems the weekend before at the Omaha contest.  I'm now going to be bringing the fuel inside overnight to at least start the flying session with room temperature fuel and maybe finding a way to keep it warmer at the field if we are going to fly in colder air.  Up until now I usually stop trying to go out in sub 58-60 degree weather.  Now that I live close to the field quick and short runs out to fly a couple flights aren't such a hassle.


Dave

[Joseph Lijoi]

Plastic RC clunk tanks work well and can be vented to uniflow by soldering a piece of tube to the clunk. I've done it many times. Works well and reliable. It's been a while but the tubing that you use is important. I think the Sullivan tubing was the best if I recall correctly.

You can mount the tank on the inboard side with the plastic tank too. I don't see the need for uniflow unless you have a muffler. I would just vent the plastic tank like the instructions and mount it on the inboard side.

I would just buy some RC fuel at the local hobby shop. Modern synthetic oil is pretty amazing. I would just go to the drugstore and buy some castor oil and dose the fuel accordingly. There are probably links to the calculations. Big Art used to tell me that if you could drink it it was good enough for your engine. 

[Brett Buck]

I’m a convert to the plastic tank. No problem with winter storage compared to metal. Plus it can be set up for Uniflow if desired. And it can be mounted on the inboard side of a profile fuse if room is an issue.

   That is probably the ideal solution in this case.

      Brett

[Dan McEntee]

I’m a convert to the plastic tank. No problem with winter storage compared to metal. Plus it can be set up for Uniflow if desired. And it can be mounted on the inboard side of a profile fuse if room is an issue.

     Plastic tanks have some of their own foibles also, if you have been doing this stuff long enough to find out. They can inexplicably split, the stoppers, no matter what color or version, start decaying from the moment they are exposed to fuel, and getting the tubes exactly where they need to be when assembling the tank can be a royal pain. They are an awkward size and configuration no matter which one you use. Sullivan makes them in a lot of different sizes and configurations but none of those were made with control line stunt models in mind and many are almost impossible to find with out going direct. I tend to use about half plastic and half metal, depending on the situation, so I am not completely against them. They are a good option but sometimes just barely.

 Type at you later,
    Dan McEntee