I am using a modded ASP Wasp on a profile plane. I am on holiday in the US and have built a quickie to enjoy a little flying! I get stuttering on hard G corners and I am certain it is the traditional stunt wedge tank that is the culprit. Smooth stunts like loops and eights are fine. Any suggestions for a suitable tank anyone?

Andrew.

P.S. The Wasp is fitted with a Cox 0.49 TD venturi and a Texas Timers NVA assembly plus a suitable bush to hold things together.

       Hello Andrew, sounds to me your mod is identical to what I did. I'm glad you went that direction. I would try and cap one of the vents off and try again leaving only one open. Hopefully that solves the problem. Are you using the muffler? Muffler pressure is always an option. Later down the road when you return home, maybe trying a uniflow pipe in the tank. Maybe try and cant the rear of the tank outboard slightly. I recently ran into a problem similar using a wedge tank on a speed job. I believe the fuel load is staying on the side of the tank and not properly making it's way to the rear due to centrifugal force. The pickup may not like being all the way to the rear of the tank and may require it to be slightly off of the rear corner of the tank.

You could drill two holes about 3/32" in the center of the tank directly in the wedge and solder a smaller wedge and make a hopper from it utilizing a pickup tube in the hopper section. This way the fuel pickup is constantly submerged in fuel. Another option is to insert the wedge from the inboard side. I didn't say mount the tank on the inboard side of the fuse, but rather have it install from the inboard side projecting out the outboard side. This way you will have centrifugal force also assist in fuel feed. You can shim the tank in and out to the desired run you like. Ken

Yep, slack bladders are the way to go IMO!

Hello everyone,
I just tried a bladder and it worked, no stuttering on hard g corners. I have to admit that I don't like using them, they are ugly! however if it works it works!
Ken, I will try your suggestions to modify the hard tank and see where we get to.

Thanks everyone,

Andrew.

Hello Rusty,
I used a party balloon and looking at it now, it looks a bit sick! . Maybe it doesn't like nitro. I simply cut a notch in the end of the tube and position the tube end about 1/4" from the "bottom" of the balloon. I have never had problems using this set up, but I occasionally lose my nerve and put an extra notch or two in the last inch of the pipe!
 
Thanks,

Andrew.

Hello Ken,
Your uniflow suggestion, together with a slight kick out at the rear, provided a trouble free system with a clear cut off at the end of the run.
  As an aside I looked at  a C/L Big Mig 0.061. The venturi diameter was huge compared to the Cox 0.049 venturi used on the Wasp. As the engines are very comparable design wise, is the Big Mig venturi too large or the Cox venturi too small? A bit academic as both engines run well with plenty of power to spare. It is just that the disparity in throat diameter is so big.

Regards,

Andrew.

I'll defer to what Ken says, but in the mean time, my guess is the Big Mig .061 venturi size reflects the larger displacement of the piston/cylinder than the .049 Tee Dee. So the .061 might pull the same vacuum through its bigger throat as the .049 pulls through the smaller one. But like you say, if they both draw fuel well, it's all academic. The Wasp might make a bit more power with the bigger venturi.