Tank SIZE for a Voodoo

LAST EDITED ON Nov-13-04 AT 07:16 AM (CST)
 
The Voodoo will be purely sport. An old 4 bolt Fox 35 for power. I will build a custom suction uniflow tank. What was the standard tank size for a Voodoo in its day? 3oz? What was the most commonly used manufactured tank?

I am not a collector . I have done some racing so a 4 bolt fox means back plate not the old 4 bolt head. SORRY. I have played with the bladders. Since it is not for combat. I will just use my favorite rule KISS. I do thank everyone for their help and suggestion. You have made me consider some points that I had not thought about.

Metal tanks were 2 1/2 to 3oz when used with crank case pressure.

Bigiron

LAST EDITED ON Nov-11-04 AT 08:41 PM (CST)
 
Typical crankcase pressure types were used before bladder tanks became popular. They were generally the long, almost square type, like a Perfect BH 512 (in Brodak catalog).

The Voodoo is almost tailor made for a baby pacifier, though. Get a 6-8 ince piece of silicone tubing, put a 3/4 ince piece of brass tubing in one end, and wrap string around the lip of a pacifier, tightening it onto the brass tubing. Tie the string and put a drop of epoxy on the knot.

The bladder compartment is even easier. Cut a beer or coke can in half. Use the bottom part of the can, and cut a plug of 3/16" balsa to seal the cut end. The spar is far enough back in the Voodoo that the can will fit next to the engine mount - just behind the engine cylinder on the right side of the wing. You may have to cut the first rib on the edge of the sheeting section, but as long as you don't cut the wing spar, this isn't an issue. Butt it up against the leading edge and engine mount with 5 minute epoxy. Cut a round hole in the can near the engine, big enough to let the pacifier slip through, and seal the edge with silicone caulk. This will keep the can edge from cutting into the pacifier or tubing.

Use a syringe to blow up the pacifier with fuel, and keep the fuel line pinched until the engine fires up off of the prime. Have fun!

The original plans, as reproduced by Bare, called for a Veco T21C, D, or E tank.

Yep!

Youre 100% correct about the Veco tank.

Any builder who desides to go that route should be sure to check the tank carefully for leaks, before installing it.

Built in is built in!

BIGS

" What constitutes the dignity of a craft is that it creates a fellowship, that it binds men together and fashions for them a common language. For there is but one problem - the problem of human relations."

LAST EDITED ON Nov-11-04 AT 09:44 PM (CST)
 
BIGS, you said a mouthful. The only way I had a no-leak metal tank to build into a "Big Iron", "Super Swoop" or one of several original designs, was to add a brass washer around the base of each tube, where it enters the tank. The extra 'beef' there really helped. This was before "Sta-Brite", however. My recollection was using 3.5 or 4 oz tanks, but on suck, it should be ok to go with 3.0 or 3.5. I seem to recall that "C" =3.0, "D" = 3.5, etc. Binky Baby Pacifiers were the cat's meow! I ran ONE all summer, and finally lost it on a free flight during the winter.

By the way, some of the local D-Bat guys make the tank plug into the bottom of the wing in the usual position. It can be bolted, wedged & glued, or banded in. A form fitting balsa plug finishes it off flush and sano. Packing tape will hold the cover in just fine. Steve

LOL!!!!

Steve...! I thought that I invented that trick! In fact, I still use it on my 'really good' tanks.

Never had one fail after doing the washer thing. I guess that genuises really do think alike!

BIGS

" What constitutes the dignity of a craft is that it creates a fellowship, that it binds men together and fashions for them a common language. For there is but one problem - the problem of human relations."

LAST EDITED ON Nov-11-04 AT 09:58 PM (CST)
 
riley would prolly say use a tank and crankcase pressure.... me bladder in th wing ... if u decide to use a bladder...put a balloon over th whole mess and tie it on securely .... for th time when th bladder bursts ... we used inkpen bladders in those days ... i used to fuelproof th th center sheeting on th inside and glue it on with fuel proof glue put about a 3/8 dia hole in back of th leading edge pop in bladder and awaaayyyy u go ... combat planes rarely lasted long enough to get fuelsoaked ... jim

>riley would prolly say use a tank and crankcase pressure....
>me bladder in th wing ...if u decide to use a bladder...put
>a balloon over th whole mess and tie it on securely also for
>th time when th bladder bursts ... jim

It's not as big a problem with pacifiers as with pen bladders or surgical tubing. Pacifiers tended to be a lot tougher. Also, the hole in the beer can is so big, a quick turn upside down, and all the fuel is out. Pen bladder tanks tended to be more imbedded in the wing, although a golf club tube solved a lot of that.

Honestly, a metal tank is a lot of hassle in a combat wing. A metal tank using crankcase pressure was the worst. Once pacifiers and pen bladders came out, metal pressure tanks disappeared off the face of the earth.

tom ... 1st time i saw a pen bladder fuel tank it was being used by jimmy reeder in his "desert streak" in 1952 ... pen bladders were around then .... bill and dale used them in th 55 nats ....the reason they werent used in combat much is because of th flooding ... in case u had to restart in a match ... we mostly used pressure tanks...u guys get to use starters ... we had to hand start ... except for speed ... bladder tanks were fussy and broke a lot ...... i hear pacifiers work better but we didnt have those then ... so i guess ur statement is partially true ... it wasnt a matter of not knowing ... jim

>tom ... 1st time i saw a pen bladder fuel tank it was being
>used by jimmy reeder in his "desert streak" in 1952 ... pen
>bladders were around then .... bill and dale used them in th
>55 nats ....the reason they werent used in combat much is
>because of th flooding ... in case u had to restart in a
>match ... we mostly used pressure tanks...u guys get to use
>starters ... we had to hand start ... except for speed ...
>bladder tanks were fussy and broke a lot ...... i hear
>pacifiers work better but we didnt have those then ... so i
>guess ur statement is partially true ... it wasnt a matter
>of not knowing ... jim

I stand corrected on the pen bladders. My brother and friends were just country boys trying to learn from our local hobby shop and the AAM magazine - and we started with Johnson's, crankcase pressure tanks, and Voodoo's (lots of fires). The first bladder tank for combat I ever saw was Dick Tyndall's Toothpick and baby pacifier. It was a few years later before I read of Howard Rush using pen bladders in the Nemesis. Availability in our hobby shops followed the same time track.

However, I've never owned an electric starter or even a chicken stick in my life. The RC guys just shake their head in amazement when I flip the prop on a 40 or 45 with my fingers. Haven't tried a 60 yet, though - but I will soon.

Honestly, nothing is as scary to start as a high compression, un-muffled Fox Mk 3-6 Combat Special with a cut down, thin blade pylon prop. But I always got injured starting Cox 049's than any other engine. Something about the lack of respect - had one crawl all the way up my arm to the elbow once. That was fun.

That is what Riley Wooten had in the original and that was shown in the kit.
Bigiron

LAST EDITED ON Nov-11-04 AT 10:35 PM (CST)
 
big iron ... i knew riley wooten very well ... i saved his last plane at th nats once ... he ran johnsons on pressure when i knew him

Running a Fox 35, there is probably nothing to be gained by running pressure of any kind. A bigger concern is getting the tank at the right height so that the engine doesn't go dead rich on outsides. One installation I remember for sport flying with a combat wing was to build in a plywood tank floor between the engine pod and the next outboard rib. The platform was at the bottom of the LE, so that the tank sat on top of it. Wire loops with rubber bands held the tank to the floor. That way, the tank could be shimmed as needed, or repaired if it leaked. Not pretty, but worked well for sport. A similar installation was shown on the Combat Cat plans unless my old memory fails me.
Steve
The older I get, the better I used to fly!

I got aquainted with Riley before the Quicker came out. I lived in Lubbock TX at the time but shortly thereafter moved to Amarillo TX (Carl Berryman territory) where I lived for the next 17 years. Carl and Riley were using crankcase pressure up until about 58 or 59. I had been running case pressure back in the early 50s in speed, so I had no trouble switching the technology to combat. Both Carl and Riley went to pen bladders mostly because they were lighter. and you could bury them in the wing, Bladders were quite prone to breaking, so up came pasifiers. I don't know who came up with them first. Then when passifiers started getting scarce some one came up with the Pippette tips and about the same time here came the surgical tubing.
Almost all the pressure bladder type systems had to have some sort of container in the wing to support the bladder and to catch the fuel and route it overboard in the event of bladder breakage.
The biggest problem with case pressure was caused by the users of that system in not getting the pressure bleed hole in the case and entry into the tank the proper size(s). I am going to build an old Quicker and put it on case pressure just to show some people around here that it can be made to run well. I will use the old Fox silver or black head combat special for power and missle mist for fuel. I have already run the setup on the test bench.

Bigiron

Baby pacifier on a Fox 35 may not be a good thing. Fox 36X...that's a different story. I bought a Veco 35 combat in 1958. The combat designation meant the crank was slightly oversized and there was a pressure fitting on the back plate. When I tried to run the Combat Veco with a baby pacifier, the crank broke as it was winding up higher than I had ever heard it run. I still have not found a new crank for this great old Veco Combat engine.
For sport flying, install a suction tank.
Just my experience.

LAST EDITED ON Nov-12-04 AT 05:04 AM (CST)
 
well norm ... that happens sometime call tony at t&a hobbylobby he may know of someone who can help 818-842-5062 maybe bob palmer or jack henry mite be able to help u

re tank:
all ya gotta do is make sure th pick up line on th inside of th tank is on th same centerline as th needle valve ... pressure or not thats important if u want it to run th same inverted as upright ... a voodoo is an upright mount as i recall ... thats a problem for bladders due to flooding if th engine stops before its out of fuel ... its a pain ...bladders are for experts ... most of them can cope with th problems ... use a gravity feed tank ... its easier ... most engines had a half inch center for th nva...but check it and make sure ... i think u had 5 minutes to run ... 4 0zs would last about that long ... mount it directly behind th engine not to th inside or itll run rich ... outside itll run lean i hope this helps ya ... good luck ... jim

Of course, we're just expressing opinions. Please understand that mine is no more important than anyone else's.

There are a couple of issues. If you are truly running an antique engine with little parts availability, putting it on a combat plane may not be the best choice. Even in the best circumstances, you will always expose it to the dirt, grass, and other foreign objects that will invariably get in the intake, the exhaust, and through the front bearing/bushing. That's because no matter what you do, it will always land in the dirt or grass - there is no landing gear.

A metal tank presents the same problem - unless you re-work the tubing. You need to make sure there are no vents that stick out of the wing, or they will constantly be ripping off from landings in the grass or dirt. The same thing happens inverted. The fuel feed is an issue, too - most feed tubes will require you to drill a hole through the wing leading edge, weakening it. A pacifier is a piece of cake compared to pulling apart a metal tank, reworking the tubing, cleaning it, and pressure testing the finished tank.

A Voodoo has a sidewinder mount - not upright. This actually means you will have a greater problem with a Fox 35 and a suction tank. A Fox 35 does not perform well with a tank on the engine thrust line, when the Fox is sideways instead of upright. The run will not be the same flying level vs. inverted. Since you can only put the tank in the wing, you have no option of altering the height (the wing is only as thick as the tank).

It's true that pressure will cause the engine to run faster, but not as much as also opening up the venturi, which is physically impossible on a Fox 35. I agree that a Fox 35 may not be the best choice with pressure, but plenty of people have done it - especially in the old days. Someone else's experience with a Veco 35 may have no validity with your case. I have personally run a Veco 19 on pacifier pressure without a venturi (maximum speed) - just the hole in the case - without any problems. Of course, that may not be a valid comparison, either.

Just my opinion.

I guess I didn't know anybetter back then. I ran metal tanks on suction as I didn't have the hot combat engines of the day. Being a teenager on a farm funds were limited. It was after I got out of high school and got my first hot Fox combat special did I have to learn how to rework a tank. Folded wing on first loop because I drilled hole thru leading edge for fuel pickup. Live and learn,DOC:)

tom ... i was goin from memory on th upright mount of th voodoo ... which fails me a lot these days ... if its a sidewinder of course it hasta be on th thrust centerline ... i personally never thought of a fox 35 as a "hot" engine ... except for overheating of course .... they did that ... i have one i picked up in a yard sale for 50 cents about 5 years ago ... it appears to have only been test run ... i thought i might use it in this t'bird II kit i have that or th "punchboard" McCoy 35 ive had about 40 years it ran good then ... i also have a 40 built by bill @ KnB in "98" ... lots of "old timers" are trying to talk me into flyin competition again ... im just not sure how involved i want to become in model flying again ... still got that temper lol ... plus someone has my old ama # and wont give it up ... it was "requested" according th lady i talked to at ama .... im not sure if it was th "swoop" i liked so much ... could have been th one hi designed called th "egad" ... it was before th voodoo ... me n danny jones flew em ... jim

Mee too,think i used the veco tanks,alyays worked. Well, i did win some.
I have one flying with a mecoy .35 from last double kit, never finished the 2nd one.
Last resort i could cut the wing open and see what i was using, if helps.
Roger

We used to use lighter fuel cans. Drill a hole in the tank and solder on a can lid to form a dome for the pressure. That helped keep the fuel from draining into the crankcase through the pressure fitting. Had one that my buddy made that he forgot to take the cardboard out of the lid. That drove me nuts for several weekends until I unsoldered the lid. Those were 4 OZ in capacity.

Someone won't give up my old ama number 42216, either. BTW, it's easier to read your posts when you add an "e" on "the"...

not usin an "e" is just a bad habit i picked up...cuttin corners.... i think most of us ran 4oz tanks for combat airplanes...riley owned a hobby shop...so he may have wanted to use something he had for sale....the old fox...ha ha ha ha...jim

LAST EDITED ON Nov-13-04 AT 01:39 PM (CST)
 
yup ... when it starts gittin too complicated ... KISS it !!!
ha ha ha ha ha ...jim

LAST EDITED ON Nov-14-04 AT 01:51 PM (CST)
 
My plans call for perfect#10