T34 Bronze Class Setup
 

I was hoping to gain some wisdom concerning powering a World Model T34 to turn 15 second laps. What I have seen is the OS55AX just will not get you down to 15 seconds and most others utilizing a YS. YS has been out of stock for over seven months now so I must seek alternatives.

Considering a Dub Jett SJ .56X that supposedly turns a 10x6 prop 18k rpm.

So asking for help on setups to include power, weight savings (battery size, tank size, all the issues you have learned along the way that you are willing to share.

Thank you

What size course are you running on? If it is the 700' two pole warbird course an OS 55ax should easily turn 15 second laps in the T34. If you having trouble getting there just add a Jett pipe to it. I have the Jett 56 and it is fast but difficult to tune. I would not recommend it. The Jett 50 is more reliable IMO.

plan on running the 700' course. We have a 55AX, maybe the engine is getting tired.

With the Jett 50 how fast should you expect your lap times?

I would expect 13 second laps flying a good course. Maybe 14 seconds here in the high desert. It would be cheaper to just add a Jett muffler to that AX55. Maybe you can borrow one from someone to try it out before you buy another engine. My flying partner was flying a stock AX55 on 30% in a World Models Voodoo and could easily break out. I think the T34 is sleeker than the Voodoo.

I would tend to agree, an OS 55 with a Jett muffler and APC 10x7 on 15% should be capable of a bronze break out. As long as the engine is running well ( no issues ) if you can’t do 10 laps in 2:30 then you are simply flying too loose of a course. This somewhat corresponds with one of the reasons why I quit racing. In gold class guys would be flying airplanes that were capable of 1:20. This allowed pilots to fly a sloppy course and still be close to breakout. Flying skill was less of a factor. My suggestion was to have the gold guys run race supplied 30% fuel to get pilot skill back into being a bigger part of being competitive. It would have reduced the wear and tear on equipment as well.

I am currently running an OS .55AX in my WM T-34 that has bad bearings, and am still capable of breaking-out. In the SAM series race, I (unfortunately) twice broke-out with times of 2:29.2 and 2:28.5; and am also known to fly a slightly larger course than many, to avoid cuts.

My set-up is with a full-size 5-cell NiMH 2000mAh battery, standard servos, etc. (In other words -- no special weight savings measures.). I run APC 10 x 8 props, with 20% nitro Morgan Cool Power fuel, and an OS #8 glow plug. Due to the bad bearings, I have even had to run a little more rich to keep the engine cooler, due to all the extra friction.

I am going to replace my bearings today, to keep from damaging my engine any further, and fully expect it to be even harder to avoid breakout times. If you are having trouble getting to the magic Number of 1:30, then try increasing to 20/20 fuel. If you still aren't there, then I'd have to agree with my friend SpeedRacer, that you are likely flying too big of a course. Perhaps have someone stationed at the Pylons to give you feedback on the course you are flying?

with the 10x8 what rpm is the oS55ax turning?

So the cause was piss poor thumbs!! Plane is well.


Thank you for all the help.

T34 First Build
 

Building a T34 for me to get my feet wet. Staying with the OS55AX with the Dub Jett pipe. Trying to keep it reliable, simple and light.

As for servos to reduce weight plan on utilizing Hitec mini HS225mg (75 ounce torque) for all the control surface.

Any tips to set the plane correctly the first time?

Nothing other then run an APC 10x7, get the CG back as far as you can with out it losing directional stability. Run the minimum amount of control deflection you can to get you around the course and practice a lot. A good caller is priceless.

One last question. With running 20% nitro and 15k rpm what glow plug is appropriate?

I think you are pushing it with 20%. The engine compression ratio is really at the point where 15% is about the max I would run. That said, try an Enya #4. The Enya plugs are a bit more durable then the OS and with the higher nitro you need a cooler plug. Rule of thumb though for what you are doing is to use the coolest plug you can that will give you some sort of decent idle. Last time I raced we had a rule that required a 4,000 rpm idle.