I just timed my TD .049 with my 3/8oz Perfect wedge and it only runs 52 seconds. I probably need about 2 oz to keep it in the air for at least 4 minutes. What a guzzler! Here's what's at the top of my list so far: http://www.brodak.com/shop_productde...ProductID=6356
Any opinions on this?
Thanks,
Rusty

Rusty --

Two ounces is a lot to hang on the front of your plane -- as the fuel burns off, it is going to shift your CG quite a bit. Keep in mind that this is ounces of fuel plus tank weight. I would be inclined to back off on the capacity a bit, maybe 1 1/4 or 1 1/2.

I'm sure you'll get other, and perhaps better, advice from the posters.

andrew

I was worried about the weight too. I wonder what most 1/2A Tee Dee C/L planes use. Probably bladders. I was hoping not to go that way but I may have to. These babies really suck the fuel in a hurry.

The more I read, the better balloons with no pressure sound. If anyone can give me a design for a balloon that will hold 1.5 to 2 oz, I'll see if I can make one for the Stuntman. I guess you enclose the balloon in some sort of holder like an aluminum cigar tube or similar?

A TD .049 guzzle more fuel than a reedy but 52 sec from a 3/8 Oz tank sound very short to me! A 2 Oz tank would be way too much for c/l were the cg shift as noted is important. Without going to a pressurized bladder system (which requires a fine thread needle) you could use a simple baloon tank. Its made similar to a bladder tank but is only filled to capacity for normal suction, it has the advantage of avoiding foaming of the fuel as there is no air in the tank which just collapse as the fuel is emptied.

Originally Posted by coriolan

A TD .049 guzzle more fuel than a reedy but 52 sec from a 3/8 Oz tank sound very short to me!

I'll recheck that with a syringe with a 30cc syringe. Maybe something was wrong with my hookup. It seemed pretty radical too. What if the venturi is bored? This engine is still kind of hard to crank, so that may be the case. I haven't looked under the screen yet.

Originally Posted by coriolan

A TD .049 guzzle more fuel than a reedy but 52 sec from a 3/8 Oz tank sound very short to me!

<snip>...... you could use a simple baloon tank. Its made similar to a bladder tank but is only filled to capacity for normal suction...........

I agree with coriolan, that's a pretty short run even for a TD. The 8cc BW tank is just a hair over 1/4 oz and you should expect 3 to 4 minutes.

The balloon tanks work well and have all the advantages he mentioned. Since they are not under pressure, they're less prone to rupture and you don't need to mess with clamps and fine needles.

Take a piece of brass or aluminum tubing and file some notches along part of it's length --- these don't have to be deep, just enough for fuel flow. Be sure to clean well -- you don't want filings in the engine!! The notches are necessary to maintain flow along the tube as the balloon collapses. Pick up a pack of small party balloons from the local cheap store. Most of these balloons have talcum powder inside, so I like to slosh a little fuel or alcohol around to wash the talcum out. Tie the balloon tightly to the tubing -- waxed dental floss is tough and the wax keeps the knots intact. Make sure to take several wraps since this juncture is the most prone to leaking. To use, first suck all the air out with a syringe and then refill with fuel. You don't want the balloon to be under pressure --- it can be dimpled. With the air drawn out first, it will contain only fuel. As the engine runs, the balloon is drawn down around the pickup tube.

You could hang it on the side of the plane, but putting it in a small box is probably better. Some folks have a hole in the covering of the first rib bay and just stuff it in. After a day's flying, cut it off and toss. It will deteriorate over time.

Originally Posted by Andrew0820

...Take a piece of brass or aluminum tubing and file some notches along part of it's length --- these don't have to be deep, just enough for fuel flow. Be sure to clean well -- you don't want filings in the engine!! The notches are necessary to maintain flow along the tube as the balloon collapses. Pick up a pack of small party balloons from the local cheap store. Most of these balloons have talcum powder inside, so I like to slosh a little fuel or alcohol around to wash the talcum out. Tie the balloon tightly to the tubing -- waxed dental floss is tough and the wax keeps the knots intact. Make sure to take several wraps since this juncture is the most prone to leaking. To use, first suck all the air out with a syringe and then refill with fuel. You don't want the balloon to be under pressure --- it can be dimpled. With the air drawn out first, it will contain only fuel. As the engine runs, the balloon is drawn down around the pickup tube.

That is what I'm going to do. Sounds like a great plan. I'll have it flying as soon as I scrounge up the tubing. Probably a refrigeration parts house would have it. We have plenty of industrial supply around here. Will copper react badly with the fuel?

Originally Posted by Andrew0820

You could hang it on the side of the plane, but putting it in a small box is probably better. Some folks have a hole in the covering of the first rib bay and just stuff it in. After a day's flying, cut it off and toss. It will deteriorate over time.

You've heard of Truck Balls, I'm sure. Maybe My plane will have nitro balls. Probably don't want to fly too low.

Just kidding

Thanks for the help,
Rusty

Originally Posted by RknRusty

I'll have it flying as soon as I scrounge up the tubing. Probably a refrigeration parts house would have it. We have plenty of industrial supply around here. Will copper react badly with the fuel?

Make life easy -- any semi-rigid tubing will work and it doesn't have to be metal. Find yourself an old ballpoint pin and cannabilize it.

Copper, like brass, will "green up" after a while (long while).

Back when I was flying the stunt pattern with TD 049's in 1/2A stunt competition, I used a 1 1/2 oz metal tank, or a pipette bulb. I think a balloon tank sounds like a good idea, but have not tried one.

I'm really surprised to hear of such a short run time. I usually get between 4 1/2 and 5 1/2 minutes on my pressure fed, bored venturi Tee Dees on one ounce. If that venturi still has the screen then it was never bored out. Try it again with the fine thread needle valve. This should give you a far more steady needle setting that can be leaned a bit more. Good luck with it.

Bob

Originally Posted by Andrew0820

Make life easy -- any semi-rigid tubing will work and it doesn't have to be metal. Find yourself an old ballpoint pin and cannabilize it.

You're so right. For someone who claims to be good at improvisation, I blew right past that one.

Originally Posted by Jim Thomerson

Back when I was flying the stunt pattern with TD 049's in 1/2A stunt competition, I used a 1 1/2 oz metal tank, or a pipette bulb. I think a balloon tank sounds like a good idea, but have not tried one.

That's what I want to be able to do, stay in the air long enough to complete the pattern in order. Until now, with the Black Widows which have to split the 8cc between up and down, I've been restricted to playing, doing whatever stunts won't cause it to sputter out; sucking air at the top of a loop and dying; only flying inverted on the very first couple of laps. My 8cc never lasts as long as many others claim theirs run. I suspect some may do more bench running than actual flying.

I have a Medallion now too, which I can use with a balloon on one of my other planes. Neither the Bean nor the Satan would accommodate a wedge tank without butchering the airframe. I bet the Li'l Satan would be scary with a TD.

Okay, I got the bladder installed today. It runs good with it, sucks every last bit of fuel out. I put roughly 2 ounces in it and it ran 6:48 with a good warning before it shut down. That's more than enough, I think 1.5 ounces will be perfect. It slows(but keeps running) when I point it nose down but runs full speed in every other position. I forgot to check the balance when the tank was full. I'm a little worried about the C/G, so I'll have to re-fill for another test run tomorrow.

This is the first time I've run the Tee Dee on a plane and actually felt it pull. It's really strong, more than I remember the BW. I had a 5.25x3 prop on it. That was the point of this project, to get my overweight plane back in the air. I'll take the camera with me when I test fly it. I think it's going to be cold and windy tomorrow. So what, I'll probably go for a flight anyway.

Ugly but functional. I ran it with the bladder on the bottom tonight. I might try it on top tomorrow. That may be a little more secure.

It took 3 four hour upload tries and then YouTube trashed the video quality. But here's what I've got.

One glaring error in my demonstration. I left out the actual fueling step, and I called a cylinder a piston. But that won't confuse any of y'all.

http://youtu.be/VMPlgF81fgc?hd=1