APC 6x4 shaft hole to large for TeeDee 049

I would do like Oldenginerod posted.
1st cut from the plastic tree the thicker of the center prop filler.
Then using a piece of fuel line insert that into the center hole to fit tightly around the screw.


If it is an APC prop for electric it would say 8x4E ("E" after the 4 lets you know it's an electric prop.)
APC has gotten cheap on supplying all the different size adapters for their props.
Years ago, that plastic "tree" would have at least six different size adapters.

I have a special drawer in my workshop for the ones I don't use. (haven't used yet!)

Don't forget to balance your prop or you'll have a bad vibration problems!

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.

@oldenginerod, The prop is not for electric so I'm good there. And thanks for the fuel tubing tip.

@sosam117, I will definately not forget to balance the props. Thank you.

@Ken, The reason I wanted to change the 5x3 prop that's on it to a 6"  prop was to make it easier to start, at least until I can sort our why the engine is so hard to start. Also Its going on a somewhat heavy stunt plane and I recall my previous TD 049 stunt plane worked well with an APC 6 x 3 prop, which the hobby shop didnt have. Thanks for the info on prop sizes. I wasnt aware APC made smaller props.
Also I suspect the tank might be the source of the problem, which is the reason i want to run it on a bladder. Thanks for the reply Ken.


Kevin.

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.

APC 4,75 x 4  , the Alu spacer has 8mm dia step.
Don't like fuel line spacers.
Short peace of Alu or brass tube would be much better solution.
Importend to ballance well all your props with spacers , less vibrations , more POWER.
 

Thanks for that solid info Ken. I believe it when you say the tanks are not good. I found that out when the filler vent slid right out of the tank as if like you said, it was never soldered. Total fail. No time for that. The tank is coming off and will spend the rest of its life in a junk box. Im going straight to  a pressure bladder.
I took the NVA off to check if the venturi was drilled, and since an 1/8" drill bit would not go through it I am assuming it wasn't drilled? I just put the NVA back on so I wont lose it, hence the incorrect position. I am going to replace it asap with an Ace RC fine thread NVA. Thanks for sharing the info. Much appreciated.
Kevin

germanbuddy wrote:APC 4,75 x 4  , the Alu spacer has 8mm dia step.
Don't like fuel line spacers.
Short peace of Alu or brass tube would be much better solution.
Importend to ballance well all your props with spacers , less vibrations , more POWER.
 

Nice Job. I have no idea what APC was thinking using such a large diameter hole.
Kevin.

Kevin the NVAs are in the mail

fredvon4 wrote:Kevin the NVAs are in the mail

Thanks Fred. They will see good use. Im going to wring that Lil Tsunami out!

As for the APC props, I found a near perfect fit for a bushing by using a roller on an old VHS tape. Just had to run a drill bit through it. Speaking of Vhs tapes please subscribe to my control line channel. There are over 500 videos converted from vhs and dvd. https://www.youtube.com/channel/UCQLZOloDrMlE4LDcTwc1wvw

from Kevin:
I have no idea what APC was thinking using such a large diameter hole.

maybe they think we run such props on our Nelson on bladder for
"the BLADDER GRABBER Combat Contest" Wash. .
Just click the APC contact button for your question.

Since APC has gotten stingy on the center prop adapters. I have found plastic tubing when I went over to the train side of my hobby shop.
There are different diameter sizes of plastic tubing that you can purchase to make up the spacers needed for what you need.
They slip into each other like the brass tubing.
The wall thickness on the plastic tubing is more than the brass tubing and you can super glue the spacers in the prop center hub when you get the right size you want.
FYI

Thanks Sosam. I suppose brass would be better than plastic, but i dont have any in stock. Pre covid days I could go into the local hobby shop and find what I need. The plastic bushing was off a smidge. It was obvious after balancing it. So i filed the hole in the bushing toward the heavy side. Also got rid of that Perfect suction tank and got the new bladder housing made and installed. I need nose weight on this plane I'm not concerned about weight. The motor is now waiting for the Ace RC NVA and some bladder hardware from Texas Timers.