Elevator / Aileron Interaction

[Zilly]

When pulling into a loop I get a very slight amount of left aileron pulling the model out of line which I can happily compensate for as I fly the loop however in the interests of getting the model to fly straight 'hands off' I am keen to understand how you could stop this interaction. I have checked for phase by lining up the flybar down the boom and checking to ensure the inner swash ball and outer ball line up and that is fine so what else can I do or is it a case of resorting to a mix on the 10X?

I am trying to avoid mixing if possible as I am concerned you can end up affecting other flight characteristics?

z

[Clintstone]

which model?

[Dr.Ben]

If you're running no mechnical phase adjustment in the model (standard for a MA model), it is entirely normal for a CW rotation model to roll off to the left with an up elevator pull. What you need to decide is whether you'd care to have the model flip cleanly and without the interaction or do more open loops in the same manner. The amount of pmix you'll require will vary between the two extremes of elevator throw. For doing a bit of both, I would suggest mixing for the situation that requires less mix, then adding in a bit more yourself as conditions demand. The reason I say this is because it is GENERALLY better to have a somewhat undermixed model than one that is overmixed. If most of your work is flipping, then by all means optimize the model to do so. In any case, 5% UP ele>RIGHT ail is a good place to start. Adjust as needed in 1-2% increments.

Note that these same concepts apply for the needed mixes for left and right rolls. In this case the amount of mix varies between that needed for ideal stationary or slow FF rolls veruss what you'd see an FAI model doing.

Ben Minor

[Zilly]

Dr Ben,

I was speaking to Chris at MA about phase adjustment and he explained how you can check to see if your phase is aligned using the flybar down the boom method and lining up the inner and outer swashplate balls.

I have checked this and it is spot on.

Chris mentioned that you could adjust the phasing by shimming out the washout arms from the base, are you familiar with this it does sound s better solution to the problem than a Pmix as it should resolve the problem in both flips and loops should'nt it?

Thanks

z

[Dr.Ben]

Zilly,

In my book, I have a radio with mixers that can be tweaked for the task at hand, so I'll always prefer to use them and keep the model at a baseline of zero degrees of phase adjustment. I've NEVER found that the most ideal phase adjustment for a loop was also perfect for a roll, and vice versa. You can get it close, but it won't be spot on. It's why the 10X, 12Z, and 14MZ keep those adjustments separate. Don't be hesitant to play with mixers. It's fun, and you can REALLY improve the way a model flies.

Ben Minor

[DaveK]

Zilly,

In my book, I have a radio with mixers that can be tweaked for the task at hand, so I'll always prefer to use them and keep the model at a baseline of zero degrees of phase adjustment. I've NEVER found that the most ideal phase adjustment for a loop was also perfect for a roll, and vice versa. You can get it close, but it won't be spot on. It's why the 10X, 12Z, and 14MZ keep those adjustments separate. Don't be hesitant to play with mixers. It's fun, and you can REALLY improve the way a model flies.

Ben Minor


Ben,

Could you give us the mixes you use and precentages to acheive slow piro's clockwise and counter clockwise to help the model to stay in one place?

Thanks in advance.

[DavidH]

Could you give us the mixes you use and precentages to acheive slow piro's clockwise and counter clockwise to help the model to stay in one place?

I am not Ben. But I believe I can answer your question. I don't know of any mixes that will help with that maneuver. One thing that will help is burning lots of fuel doing the maneuvers and figure out what the heli does when it is in certain orientations and the wind hits it from a certain direction.

On the piros one thing that is just about constant. The nose will want to dip in one direction and come up in the other direction when the piro is first started.

With slow piros there is so many varibles that come into play. Wind changes what the model wants to do depending on what direction it is hitting it from. So to hold the model in one place while doing the slow piro. You just have to practice them enough that it becomes second nature to make the correction needed when needed.

David

[Dr.Ben]

I do run two mixers in hover to help clean up the piros. They don't work perfectly for all conditions, but since I've optimized the delta and feedback ratios in my head so the model sits better at all angles to the wind, they do work a lot better. It is best if you can do the mixing yourself, but the mixers do make it easier. If I could priactice every day like Wayne, Dwight and a few others, I could program my head to do this work. As it stands right now, the mixers make a demonstrable difference in how hard I have to work in piros.

The first thing you need to do is get the model hands off in trim in calm wind. I generally fiddle with the pitch axis first. At my usual piro rate, I adjust a linear pmix until the model sits still for one rudder direction. I then repeat it for the other rudder direction. It then repeat the procedure for the rud>roll interaction for both left and right rudder. I can't really give you concrete mix percentages because there are so manner variables such as piro rate, model type, and so forth that come into play. For starters, though, begin with 5% in the correct direction and tweak up or down from there. Don't be surprised if it takes more mixer % than you might have expected.

Ben Minor