I experimented with a 6oz bubbless bladder tank set up on the centre of gravity in my Taipan on Monday and had the strangest result that I'd appreciate comment on. I've made a bladder tank out of a square Kavan tank of similar dimensions to a Tetra tank, about 2" square by 4" long. The TT46PRO engine would needle perfectly on the ground, launch well and do the first lap running normally, then after one lap it would slow to about half revs.

There are no kinks or leaks in the suction or pressure lines. The muffler pressure nipple is clear.

I thought that if the tank was too far back for the muffler pressure available that the engine would die on takeoff when it experienced the first strong acceleration effects - not after one lap.

I'm keen to get this to work if there is a solution because the tank is right on the c of g so there is no balance change as the fuel is burnt off.

Any comments would be appreciated.

Should not be a problem with your set-up. I p[lace my tanks on the balance point. The balance point on my Q racers is 3" back from the L.E.

Some ideas.

Is the pressure line nipple hole at the engine end big enough or possibly blocked?

Is the tank truly airtight and not leaking any air?

The fuel pickup in the bag should go just half way into the tank, not all the way to the rear.

There is a possibility that the bag blocks the end of the pick-up. I cut a vee into the end of the pickup to prevent this. I also pierce a small hole across the pick-up line 1/2" or so up from the vee. I use a small prass tube to pierce the hole.

Could it be a radio problem and the engine is idling down?

That is it, I cannot think of anything else.

Ed S