Although I have been a member or this forum for some time, this is my first post, so if this is the wrong forum, please redirect me. Ok, here is the deal. My local club hosts 4 Star 40 races throughout the summer. The rules of competition include: must be a stock built (per the Sig plan kit) plane weighing no less than 4 3/4 lbs without fuel, a stock Supertiger GS40 engine with stock muffler, stock carb, stock exhaust and cannot exceed 15k rpms on the ground, a Master Airscrew 10x6 prop, and fuel containing no more than 15% nitro. Other than this, we can change the bearings, however, the head gasket must remain in place. Now that you know the rules, a little about the reason for my post. Our first race was 2 weeks ago, and although I did not enter, I went to the field to watch. I left with the impression that the secret to success was in making tight corners, and flying a smooth and level pattern. However, today while at the field, 4 of us had 4 Star 40's with us. Two of the 4 are extremely competitve in all the events and wanted to have a friendly race. My plane weights in right at 4 3/4 lbs, and I have a stock ST 40 with a punched out exhaust baffle, and have my exhaust pipe mounted 5/8" outward of the flange. Other than this it is straight out of the box. The 2 who are extremely competive are running Italian made ST 40's which are also legal. Long story short is I ran a pretty clean race and was able to keep up for about 5 laps. After this, they got tired of playing, and in a 10 lap race finished well over a 1/2 lap ahead of me. If your still reading, my question is this. I use to race dirt track stock cars, and know that local competitors will share some secrets, but they usually keep the really good ones to themselves. What tweeks/modifications can I make to my ST 40 get more power and speed? Does the Italian version of the ST 40 run that much better? Final thing is my engine was tuned and running really well. I was turning right at 14700rpm, didn't bog or loose time in the corners, but was instead out performed. I brought a Nationwide car to a Cup series race. Keep in mind, there is no tear down or claim rule in these competitions, and although the winning prize is pittance, I would love to put somthing out there to at least compete.

Thanks in advance for reading this long post, and for any feedback your willing to share.

Jr

Not wishing to start a controversy but, In my experience most of the people that cannot keep up "Imply" that others have Special" engines, When in actual fact they were simply outflown.

Ed S

Are you sure that they were winning because of more power or flying a tighter course? These types of planes are so restricted by th plane itself and then having to use the same prop. Were you able to find out what RPM the other guys were turning? My guess is they were just flying cleaner. Try using some expo and reduce control throws and this may help to smooth things out.

Jr,

I race 424 which is a lot like what you are racing, being as we all run the same equipment with the same rpm, etc. When I first got going, I thought I was being beaten by better equipment too. EVERYONE starting out will think that.

We got the Eagletree onboard telemetry system and we started testing things to see what would make us faster, and what slowed us down. What we found that slower us down the most was rolling the plane and hard pulls on the elevator. By only rolling when we had too, and not over pulling or constant corrections, we gained speed quickly. By learning to hold a slight angle down the straight-a-aways, we didn't have to roll as much. By learning to push while banked to move out during a lap (instead of rolling 90 degrees, pulling, rolling 90 degrees back) we were able to maintain more speed. Every correction you make, you lose speed. Only when you relax the controls will the plane accelerate again. I help a lot of people to try to get faster, and when they ease up on the control inputs and fly a tighter course, they ALL see an increase in speeds.

Good luck, and always remember it is all supposed to be FUN!

The consensus on the forums is that the Chinease assembled ST's are just as good as the Italian ones.

Jr25

I am inferring that you have very limited, if any pylon experience. You didn't actually say how experienced you were.

Pay very careful attention to what "Ed Smith", "vertical grimace", and "Scorpion Racing" told you. They have told you the most effective "speed secrets" there are.

It is my opinion that you must first work on and perfect your flying skills and racing techniques, then look to more engine/airframe performance.

Have fun with your pylon event.

Doug Bebensee

Those two sentences alone may show you the difference. There's a fine line between being tight and too tight. If you're pulling too hard and turning too tight, you'll slow down too much. Most new racers use way more control than they need. Any excess deflection will slow you down.

I'd be willing to bet that the top racers aren't cheating. Usually it's the guys just behind them, that don't want to believe that they're flying's not up to the task, that would start to cheat if they felt they could get away with it.

Thanks for all the great feedback. Admittingly, I have no where near the racing or even flying experience of these other gentlemen. Looks like practice, practice, practice is the best way to increase speed.

Antoher question before I put this to rest completely. Would changing my stock bearings to ceramic make enough of a difference to justify spending the money on them?

Thanks,
Jr

I replace the factory bearings prior to ever running a new engine. For 424, I use the Boca Bearing High Performance bearings (ENK-001HP for the TT) for under $40.00. The factory bearings will start to lose power and slow some after 10 or 15 runs. The HP bearings will last a year or better without a loss in power. The ceramic bearings won't give you any better performance, but will last a little longer than the factory stock, HP or HS bearings.

Not sure what size the ST uses, but Dave S. sells Swiss made rear bearings (same as used in the nelsons) for some sport .40 motors out there. I use them in the .46 OS AX and they work great.

Not bad at $18 / ea

I have used ceramics and have noticed no advantage.

How is your airplane balanced? Moving the CG back and cutting down the throws will help. And you should consider a tetra or Jett bubbleless tank.

Just a quick observation, 14.7K and 15K over a 10 lap course with everything else even and you should see some seperation. Maybe the other planes engines were running just slightly faster? Then there is the possibility that the other airframes had a little less drag. Maybe Jr just flew a little longer in each turn. Basically what I'm getting at is that when everything is even, there are a lot of things that can seperate one or many from the pack. Usually the best equalizer is pratice. Best thing to keep in mind is to have fun. Best of luck.
Jimmy Skids

Agree with everything you guys have said. In fact, Jimmy makes a great point in that if tuning the engine to pick up an additional few hundred RMP (without getting it too lean) would make a big difference over the course of several laps. The plane is slightly nose heavy, but not bad at all. In fact, I could probably add a little nose weight and not hurt a thing. I am completely trimmed out, and she flys pretty much level without the need of any elevator trim.

I'm going to try a new set of bearings ($23.95 from Rc-Bearings.com) and continue to practice making consistant laps every time I am at the field.

Thanks,
Jr

A nose heavy plane takes more elevator throw to turn and slows down more in the turns than a plane with a rearward cg.

Keep moving the CG back until it starts to get squirlly. You don't want it squirlly, but you want it as close to that and still be controllable.

Don't get too hung up on ground rpm. What matters is how a motor unloads in the air, a plane with a cleaner airframe will unload better than a dirty one.

The speed secrets thread may help with ideas in cleaning up your airframe and prop maintenance. The series of articles can be found here. They are a couple years old, but still contain a few ideas that may help you out.

http://www.rcuniverse.com/forum/m_3980534/tm.htm