rudder or engine thrust

[mrbigg]

Wasn't it Chip Hyde who uses a throttle to right rudder mix with a zero degree engine setting?

[Walt]

At 1/2+ throttle fly the plane straight at yourself at a safe distance with a no wind condition, preferably by yourself for obvious reasons. Concentrate on getting the wings dead on level coming towards you, its easy to see at this attitude. Easily pull the plane vertical at 1/2 throttle and watch the plane transition into the vertical climb. Adjust rudder trim for the plane to enter and establish the climb straight. when you get this down, go to full throttle and do it again. Usually if there's a trim issue that re appears it may indicate the need for more engine offset. It'll take time to dial this in but this was the way I was taught for the initial check and a starting point for rudder trim, it works. I have also found that if a plane is straight and your construction numbers are right there's usually no reason for a plane to require more than 2-1/2 degrees offset on the thrust line. I did mention usually BTW.....Prop's and CG changes will require you to start over again....

[Flybye Steve]

I hava a EF 100cc Yak and have found it requires considerable "right rudder" trim to sustain true vertical up lines. Interestingly, I have the "right" trim mixed out at low throttle for straight down lines. Also, I have a simular throttle/elevator trim; a small amount of "down elevator" at low throttle neutral in the middle range and a little more down elevator at full throttle. I have a DA100L on Grieves pipes with a Mej. 25/12 three blade prop. I'm not sure changing the engine thrust angle would work as well as the mixes. I also noticed there seems to be a much more pronounced tendency to pull to the left (requiring more right rudder) when transitioning into an up line at full throttle as opposed to feeding in throttle gradually during the transition. As the plane slows during a "Stall Turn" , it would immediatly start turning to the right until I mixed out the "right rudder trim" at low throttle. It seems complicated, but it works.

[nate428]

mixes have to be fine tuned between inputs on the sticks and actual flight path/speed of the plane... so as this transition happens the mix will under or over perform its function. i prefer to spend time to correct the thrust angle not the mixes, and have my plane fly correct all the time.

[The Dirt Doctor]

	Quote: Originally Posted by Flybye Steve
	I hava a EF 100cc Yak and have found it requires considerable "right rudder" trim to sustain true vertical up lines. Interestingly, I have the "right" trim mixed out at low throttle for straight down lines. Also, I have a simular throttle/elevator trim; a small amount of "down elevator" at low throttle neutral in the middle range and a little more down elevator at full throttle. I have a DA100L on Grieves pipes with a Mej. 25/12 three blade prop. I'm not sure changing the engine thrust angle would work as well as the mixes. I also noticed there seems to be a much more pronounced tendency to pull to the left (requiring more right rudder) when transitioning into an up line at full throttle as opposed to feeding in throttle gradually during the transition. As the plane slows during a "Stall Turn" , it would immediatly start turning to the right until I mixed out the "right rudder trim" at low throttle. It seems complicated, but it works.

I have a flight mode set just for the hammerhead stall turn - all of the rudder to ail and rudder to elev mixes are both turned off. On the downline I usually flip the FM switch back to normal flying with the rud to ail * ele mixing on.

Bobby aka TDD

[Flybye Steve]

TDD, Interesting approach. I,m wondering why all of this is required on this particular plane. I can't figure out if I'm now beginning to see these issues due to advancement in IMAC flying skills (the more you compete, the more you see smaller imperfections) or if it's an issue with this particular plane. This same plane won the Stortsman class at the Nationals so I have to wonder if Reiley had all of these mixes or just a lot of flying skill.

[The Dirt Doctor]

	Quote: Originally Posted by Flybye Steve
	TDD, Interesting approach. I,m wondering why all of this is required on this particular plane. I can't figure out if I'm now beginning to see these issues due to advancement in IMAC flying skills (the more you compete, the more you see smaller imperfections) or if it's an issue with this particular plane. This same plane won the Stortsman class at the Nationals so I have to wonder if Reiley had all of these mixes or just a lot of flying skill.

My guess is that he had both!! A plane that is almost perfectly trimmed out is much, much easier to fly than one that is not! Take that a pilot with lots of skill and it's a winning combination.

Bobby aka TDD

[jack strickland]

	Quote: Originally Posted by The Dirt Doctor
	My guess is that he had both!! A plane that is almost perfectly trimmed out is much, much easier to fly than one that is not! Take that a pilot with lots of skill and it's a winning combination. Bobby aka TDD

Hi Bobby
I have noticed a lot of posts refer to cg, but no one has stated where it must be. In my opinion there is only ONE placement of the cg, and that it is correct when at wide open throttle, flying level and rolling to inverted, the plane should not start to decend. As a general starting point for the cg, it should be near the thickest part of the airfoil, and move as required. It takes a lot of time to get this done, but when it is done, the plane will be a lot easier to fly, and the other adjustments will be easier also. Just my opinion. What do you all think?
Cheers

[JEFFRO503]

jack.....do you mean a slow roll or a fast roll? If it is going in a slow roll , and when it hit knife edge position , wouldn't the cowl start pointing downwards at that time? I myself am on the same page as you though. I "used" to like my airplane a little tail heavy for 3D type flight , but i have since moved my CG so it's centered pretty well. Pretty much hands off on inverted and right side up flight.....at least that works for me.

[Billa]

Have never tried a 0-0 thrust so can not comment. I like to get the thrust just right without having to use the throttle rudder mix. In the old days when our power to weight ratio would not allow us to hover, you could easily tell a thrust problem from a rudder trim problem - if the plane did not have enough right thrust, it would veer to the left in an upline as it slowed down and making the right rudder more and more ineffective as it came to a stop. Eversince, I had never thought of using a mix to correct the requirement of right thrust.
But as someone said earlier, gassers don't need that much right thrust to begin with. I was really skeptical about the 1.5 deg ( if I rememeber correctly) of right thrust recommended on the 37.5% Pilot RC Yak but that is where I left it initially and suprisingly, it was spot on for IMAC and 3D.
With a centered rudder, perhaps you could pull up into an upline with just enough throttle to hover the plane (previously determined) and see which side the plane falls to. If it veers to the left, increase right thrust and if it veers to the right, decrease the right thrust.
As for the C.G., it is not a good idea (i.m.h.o.) to have a plane which is so neutral that it requires no elevator input when rolled inverted. You will have a very touchy airplane no matter how much expo you feed in. The way I test a plane for correct CG (and I must have read this somewhere) is to pull up into a 45 deg upline and roll inverted - if it continues at 45 deg, you've got the CG in the just the right spot. If it drops the nose, you are bit nose heavy and if it climbs up, a bit tail heavy. You can follow this up with a straight and level inverted pass and see if you like the feel of the amount of down elevator and adjust CG/throw from there. This is not to be confused with where you like to trim your plane. Some (competition) flyers will not trim for upright flight even with a slightly forward CG because the sequence they fly hardly requires them to be upright at any length of time during the flight. For most of us, a slightly forward CG and the necessary uptrim required for hands off upright flight works quite well.

My 2c.

[Billa]

My apologies to Mr. Strickland and Jeffro503 for challenging their understanding of a correct CG. I was only expressing my opinion for the benefit of the newer fliers. I gather from your number of posts that you have come to these conclusions through experience. It is just that it doesn't work for most of the guys I fly with. Nonetheless, my bad.

[JEFFRO503]

Hey Billa.....don't worry about it man , i need all the advice i can get. I have only been flying for 3 years and when someone with a ton of experience puts things into Lamens terms , i tend to listen and try to learn. I'm actually taking your advice and am going to play around with my CG and balance this next weekend. I have only 18 flights so far on my 89" slick , and have had so much fun with the thing , i haven't really tried dialing to much of anything in just yet.