APC 6x4 shaft hole to large for TeeDee 049

Kevin, first question I have is why are you using a 6x4 on a Tee Dee? Seeing you had inquired to me in regards to the Voodoo, I'm assuming this is a combat 1/2A? You also asked for a fine threaded needle valve. When running bladder, you need to run smaller props then you would on suction. Even with a fine threaded needle valve having so much prop on the engine makes the needle hard to set. You either need to shrink your prop or increase your nitro above 35%. With the price of nitro today, it's easier to opt for the other.  5" max on a TD.

For instance, when we fly .25 engine sized combat we run 8" props. The TD even on suction wants to run small props. Good size APC props for a TD would be the 4.4 x 4, 4.4x2. The APC 4.5 x 3.5 is my go to prop. However, even with the smaller props, they're not going to fit. I had bushings made and I was selling them on EBAY years back. I've been very generous giving them away and I kept only a small amount. I might have some more.

APC 6x4 makes great thrust and pitch speed performance with the Norvel .074 and TT .07

I use the small ID insert and fill the void with suitable dia. fuel line. Tube expands with
the prop bolt and during compression enough for a snug centered fit if cut a bit long.




Norvel .074 static stats: 30% Nitro 20% Castor
Static test APC 6x4E - Modified Heli Muffler 19,147 rpm
196w / .262hp / 22oz thrust / 73 mph pitch speed



 

Brad, I have a lot of admiration for what you do with those props. I also modify props and I know what I need to do to them for my useage. I should be going to the next level as yourself and do more. Seeing that we have a speed limit, I alter the prop generally to slow it down vs gain more.

Thank you Ken, becomes a balance of good thrust and top end speed on my end.
Most small engines can always benefit from prop development.

Norvel AME .061 with an aggressive pitch 4.2 x 6.5N
A 5x7.5N has been set up for the Norvel .074.

Kevin, I can already see issues. Your on the right track using a narrower longer wedge like you have done. The problem is that the tank is still too wide off of the fuse. You can place a slightly thicker shim under the engine lugs even if it's a 1/16". I don't typically recommend engine offset but in this case even another washer under the front lug kicks the centerline of venturi further outboard. You can also flip the needle valve assembly over which will place the barb of the carb body further out as well it will also get the needle further away from your prop for your fingers.  That looks like a Perfect tank and truthfully, they're crap. Yes, they worked for many but they have a lot of flaws. If it's a Brodak version it's even worse.

              See how your fuel line is going up and then down and then back up to your needle valve body. That's a BIG problem. Second, the brass tubing they used is complete crap. Tubing isn't seamless and old Perfect tubing splits and you can't see it. Third and most important, Perfect NEVER SOLDERED THE TUBING inside. I mention this a million times and there's those that don't believe this is a issue and like to fiddle with stuff for a eternity. I will tell you first hand it needs to be soldered in the center of the wedge approx 1/8-1/4" off of the back wall.

If it's not split now it will be at some point.  Remove that brass and replace it with K&S 1/8 tubing and not the 3/32" crap they use.  Don't put the tubing back in the hole you removed it. Put it straight in through the front end cap as far to the outside as possible. In other words right down the center on the outboard side and solder it in the rear. This will make  the fuel line  shorter and it's a straighter shot to your needle valve.

            To use the engine properly, the tank really should be made into uniflow but I've experienced problems with doing using wedge shaped tanks like you have   as I feel it causes a backlash of turbulence internally inside the tank.

                   Did you air test this tank as if you were trying to pop it? This is critical and needs to be done . Even one little pin hole the engine will not draw fuel properly. Try using a drinking straw with a pin hole in it. A bladder will resolve all of your issues but that tank can be made to work and even flipping your needle valve over should improve what I already see.

I see the screen on the venturi, I have drilled and opened up venturi's but the screen on it makes a bit more difficult to do so. You never know if the venturi is opened up unless it's checked. 5/32" is the max before breaking into the jet holes but if the venturi has been opened too far, the engine usually quits a second or two after you release it. This wouldn't be a issue using a bladder.