TailTwister

My Feedback: (1)

I'm considering the tank in the left wing option for my Su-Do-Khoi 60. The plane came with a tank that looks like that's what it is for.

#1 Does this rule out sustained left rudder knife edge? I can't believe the fuel line inside the tank won't kink. Has anyone tried a "T" fitting with a second klunk nearer the front (inboard) side of the tank? Good idea or bad? I guess if it didn't kink, I could be sucking air. (See #3 regarding a header tank)

#2 I guess I just would need a little platform in there and some foam padding?

#3 I'd probably add a 4 ounce (or so) header tank just behind the engine so I can monitor the fuel level. Anybody think that's bad with a YS 91 FZ?

#4 I'd try to keep the lines as much "inside" the fuselage as possible. Any problems here?

There's always a leak possibility, so I usually silicon my stoppers in and use mini wire ties on fuel line connections.


Any input is welcome.

wgeffon

My Feedback: (4)

Frank.

You'll need to devise a way to get the tubes on and off so that the wing can be removed..

T fittings or the like should work.

TailTwister

My Feedback: (1)

I was thinking some barbed fittings were in order. I'd just have them so they could slip into the wing cavity by the tank. It looks like your tank is all but touching the wing. How big is your tank and how close is it to the wing?

Kevins_RC

My Feedback: (1)

I know that we have tried to use header tanks on a YS in Helis. I realize that you are using a 4-stroke, verses the Helis are using 2-Strokes, but YS pumps didn't seem to like the header tanks at all. I had one on my 60 size heli, and it kept dieing regarding what I did until I removed the header tank. Others at our field have experienced the same results with a header tank on a YS. I would suggest that you contact the manuf. or at least the Distributor and ask them able the use of a header tank.
Good Luck & Happy Flying!
Kevin

TailTwister

My Feedback: (1)

Any comment on the 2 klunk set-up? The tank is long and thin, so it can slide into the leading edge of the wing. That puts the stopper just inside facing the inboard wing rib. With the long ways part of the tank in the wing side to side, I worry about losing fuel at the klunk due to the effect of gravity on the fuel. If I flew it knife edge using left rudder, it would seem to either kink the line (if the line flexed inward), or if the line did not kink (it stays straight) it would be out of the fuel inside of the tank. If I put a "T" right inside the tank with a second klunk pointing to the innermost rear of the tank, would it help or hurt? I think it would be OK if the inside line was very flexable to guarantee the kink. Then I would only have the short klunk sucking fuel. If the line were too stiff, and the line did not kink, then I think I'd be sucking air. I'd like to try the wing tank, but I'm still not stuck on it. Maybe if I positioned the tank so that the outboard end of the tank were slightly to the rear, and the inboard end were slightly forward, forward momentum would keep fuel to the outboard portion of the tank? What about that?

Thanks,

Kevins_RC

My Feedback: (1)

To me, 2-klunks would not work any better than 1. If you think about it, if one is submersed while the other is not, you'd still be sucking some air. I realize that the Pattern guys do this all the time. Maybe you ought to throw a posting up in on a Pattern forum and see that these guys have to say. The Pattern guys would also have more exposure and experience with the YS 4C motors too. It can't hurt to ask.
Kevin

TailTwister

My Feedback: (1)

Yup, it finally hit me. Any "short" klunk to guarantee fuel flow in left hand knife edge will suck air in right hand knife edge.

Anybody have experience with YS 4 strokes and header tanks?

What if I canted the outboard end of the tank just a bit aft, and the inboard forward? Would the momentum of the plane then keep fuel near the klunk? Or would gravity just overcome the angle?

rcman-RCU

My Feedback: (31)

Here's my 2 cents on the subject:

If you install the tank with the clunk bouncing around in the left end of the tank, you may have a problem with sustained left rudder knife edge. The clunk will suck air. You could shorten the fuel tubing on the clunk so that the clunk ended up in the middle of the tank. Then you would only start having problems when the tank was less than half full.

Some guys notch out the leading edge of the wing to have room to mount the tank in front of the wing against the fuse.

The other option would be to install the tank behind the spars with the clunk at the back of the tank. The YS pumped fuel system won't care and all your problems would be gone.

TailTwister

My Feedback: (1)

rcman- Thanks for the input, I'd prefer not to cut the plane at the wing. I'd elect a smaller tank and drastically cut flight times first. The tank behind the spar is a good idea, except that puts in in the servo hatch between the wing tube and alignment pin tube. There is just no room. I tried to cram it in there, because I like that idea.

If I go with the tank in the wing, I can cant the tank, outboard to the rear, and I can get about 3/4 of an inch diference from the front (inboard) end of the tank. With forward motion, does anyone think that would keep the fuel out there? Obviously with acceleration it would, but as the plane slowed, I guess the fuel would follow gravity.

Maybe I just should always do right hand knife edge?
Maybe I should just go with a smaller tank on the fuselage?

The wing tank really "cleans up" the look of the plane, but maybe it's just a hastle, and I'd be waiting for disaster.

Thanks for the help so far, any other ideas?

rcman-RCU

My Feedback: (31)

Last idea:

Make a custom shaped brass tank. The control line guys used to make their own tanks all the time. This would involve some work, but is doable.

TailTwister

My Feedback: (1)

Been there done that. I'm one of those control line guys, and that has passed through my mind. I envisioned a flat leading edge and an angled shape towards rear left. Then I figured that was no better or worse the just rotating the tank that I already have.
rcman- I must say, you are really digging in here to help out! Not many RC'ers would consider building a brass tank to be an option.

rcman-RCU

My Feedback: (31)

Use one of the tanks with the bladder inside. These tanks do not use a clunk. The position and shape of the tank have almost zero affect on fuel draw. This would definitely solve your problem. Several on line hobby shops, including Don's or Central sell them. There was an article in one of the RC magazines within the past couple of months that shows how to make your own using baby bottle liners and the tank of your choice.

TailTwister

My Feedback: (1)

I e-mailed Performance Specialties about the use of these tanks. It seems to me that these tanks would not be compatible with the YS pressure system, but we'll see what they say. Once again a great suggestion.
Thanks,

TailTwister

My Feedback: (1)

Performance Specialties says the tanks will work but will not fit into the wing. They advised me to put the tank on the side of the fuselage to avoid future problems anyway. Too many people have now said that for me to continue to ignore. I guess a smaller, fuselage mounted, tank is in order here.

Grumbel, grumble, grumbel...

rcman-RCU

My Feedback: (31)

There are at least 2 or 3 companies that make these tanks. You may have to do a little digging. Also, I think you have to fill these tanks with a fuel syringe to avoid overfilling and popping the bladder. Another side benefit is the tanks do not allow the fuel to foam, so you don't need foam any foam padding around the tank.

TailTwister

My Feedback: (1)

Yeah, the syringe is required. I think I'm going with the fuselage mounted tank, probably cutting the wing so that it is in line with the engine. It's not my first choice, but it's a lot simpler than the wing tank.

There is always the chance of a seam leak, you know...

I also may drop the YS and go to a 2 stroke.

TailTwister

My Feedback: (1)

I went and got a Du-Bro (recommended by Performance Specialties) 12 ounce tank that will fit on the left side of the fuselage. It will go all but directly beneath the engine. The YS has a forward fuel inlet, even though it is truly a rear intake, and it will be OK. I don't really like the way it looks as much as the wing tank, but it is functional and servicable. It puts the tank well forward of the CG as well, which I had hoped to avoid. I decided not to cut the wing at all.

By the way, the recommended (by Performance Specialties) Du-Bro stopper system looks just like the not recommended Sullivan system. What gives?

rcman-RCU

My Feedback: (31)

I had a YS 91FZ engine. It was the best running engine I have had. It is also a real fuel miser. You could definitely get by with a 10 ounce tank, maybe even an 8 ounce. I could fly for 20 minutes on a 12 ounce tank. Good luck with the project.

TailTwister

My Feedback: (1)

Thanks, I have run the engine only for about 10 ounces total. I wanted to see if it would "blow up" the tank I had. I must say that as this is only my second 4 stroke, I'm still lost. The other one is a Saito 72. Both engines are a real pain to start, and do not seem to run consistently. I hope after some run time they will be better. This engine needs to turn a 16x4 at about 10,000 rpm to make me happy. Most people feel that it will, but many people said the 72 would do 10,000 on a 14x4 too. I promise you it will not (on 20/20 fuel anyway). It peaks around 9800, and is safe to run at about 9600. It's not a big difference, but still. I know that my Rossi on a 12 inch prop can do 14,500 so the thrust numbers are similar. There is a lot to say for familiarity, as long as the numbers are close, I'm happy with 2 strokes. Between Saito and YS, If I can't have a good 4 stroke experience, there isn't one to be had. I've been told that they are the best around.