Also known as "flaperon" mixing, i.e. proportional down flap with up elevator and vice versa.

How much is enough?
How do you determine when you have too much?

Only objective is tight loops with no snaps, right?

With the mixer turned off, and playing with aileron droop, I notice down ailerons make the plane pitch down, up ailerons make the plane pitch up. Is this normal behavior?

I trim the airplane pitch by setting the elevator level with the stab, and setting aileron droop so trim is neutral in flight. This is something I do after I have the engine thrust line to my liking. Any problem with this strategy?

Note from the above, turning the mixer on will cause the flaps to cancel out some/most of the elevator pitch input. I have crashed a plane because of this, and not paying attention. Look Mom, no "up" :stupid:

I find myself cranking more and more elevator throw into my plane, only to increase the amount of flap defection with the mixer (Which of course seems to cancel out most of it)

How far is enough?
How tight should be loops get on a properly set up plane?
At what point do you conclude there is no (further) benefit?
What types of planes are better/less suited to this mix?

Is there a FAQ anywhere on setting up / trimming FF planes?

Martyg,

I don't know of a rule of thumb set in stone for this. The closest I've ever heard was perform your tightest loop with no mixing, then add flaperon mix to tighten the loop, performing the tightest loop you can, till you almost snap out, then stop. This is how I do it anyway. I don't fly at the NCFFA Nats yet, but I hope to one day and I am guessing my way is as good as anyones. If anyone from NCFFA wants to chime in, we'd love to hear your technique, as well as any others.

Foamguy

how much depends first on your plane and then you....
first how much will you plane take. the flap mixing shouldn't cancel out elevator or plane reaction to elevator. find out how much controlable elevator throw you can get into your plane with out the plane acting crazy and then set that at the high rate point. then set a lower rate for normal type flying. now go back to high rate and start adding the flap function a little at a time untill you see what you want. if you want the plane to snap loop mix it till it snaps. ( not all plans will snap loop) when you find your desired high rate mix go back and do the same for the low rate. then set expodential if you like.
for me it takes a while to find the right rate and mix for my funfly planes. I fly mostly Menaces and each one reacts different to mixing. up to lately ( at slow speeds) i always felt that with the mixing on the plane tends NOT to balloon as much because an elevator command with the mix on is actually distributed through the whole plane rather than just a shift in angle of attack. i flet that if I apply up elevator and the flaps drop besides creating more lift, they also creat more drag there for hindering ballooning to an extent. but on my last menace things seemed to be the opposite. I believe it has alot to do with the cg location though.
I usually fly on high aileron and low elevator with the mix on.
i keep the high elevator cranked real high and only use it for a flat spin or snap loop or an event. it's great for events because i can do a loop right off the runway and the plane just about stays stationary in the air. keeps my landing time down.
that's the way I do it. i'm sure everyone has their own way of dialing in a funfly.
nuturalize your elevator and flaps. fly the plane level see what it does. you may have to work your flaps for level flight then roll it over and see how far off of level flight you are. you may have to work your cg some to get it to fly true nutural..
what plane are you working with anyway...???
you may not be able to set the plane up for level flight both inverted and upright.

what they said...but, flaperon mixing is the use of ailerons for flap purposes. FLAPs...ailERON> flaperon.
ele>flap mixing, and flap>ele mixing are called flap>ele mixing, etc.

Ele.>Flap mixing won't work well with a nose heavy plane . Try setting C/G at 30% .
Maj. Crash

bugseigel: Rates? You mean there is something other than high?

Marty:

This really depends on your plane, what it will do, tail moment (hinge-to-hinge), balance, moving surface sizes, and servo torque and linkages.

I will breifly discuss the setups used on stick-boom unlimited competition birds with good servos, plenty of moving surface, and plenty of good old Webra thrust.

Typically, the boom plane is 19.5 to 20" hinge to hinge, and I run about 5.5" ailerons on an offset pull-pull. Others are as small as 4". I run JR 4721 servos on a 6-volt NiCd pack. Pulling about 3amps, so NmHi are not recommended.

There are two setups: One traditionally recognized, and mine. Both work, though depending on the plane, your results may vary.

The first setup is outlined by someone else above. It consists of looping as tight as you can without mix, then add mix to tighten up the loops. This makes a nice, controllable "flying loop".

My setup began out of ignorance, but has resulted in tight loops that this year were the envy of all at the NCFFA nationals. It may not apply to all planes, but it sure works for me. I applied it to multi-year-champion David Grantham's plane this year when he had loop trouble, and it fixed him right up. Yeh, he even beat me with it.

I set up for maximum physical throw on the elevator. It hits my vertical fin post, about 65 degrees or so. This requires a strong servo. My pull-pull hords are set back from the hinge line so some holding torque is preserved at these high throws. The bottom line goes slack in this situation. The plane WILL NOT LOOP at all without mixing, way too much elevator.

Now I start cranking in mix, and eventually get a nice loop. I keep adding mix until the plane "reverses" after about 5 consecutive flips. By this, I mean the inside loop turns into an outside loop. Be ready for this, try it high, and be ready to turn off mixing to get it back down if this happens. Now, back off on the mix about 2-3 percent, and you have it. On my JR radio, I end up with about 100% mixing. However, this percentage will depend on your servos, linkages, etc., so it means nothing that I am at 100%.

This approach requires STRONG flap servos and a strong motor. If the motor sags, the loops will fall off or reverse, so be sure to set it rich!

You are right, the flaps have an opposite effect. However, if the moments are right and the mixing set and the power up, they work together in this fight, and the result is a loop in the length of the plane.

The first approach will safely get decent loops with many types of planes. The second will get you an edge, given a plane.

Let us know what plane you are setting up.

Guys, thanks for the follow ups.
I have a couple of ideas to try when I go out testing tomorrow.

The plane I am setting up is a scratch built open-B combat plane me and some buddies in Dallas have been refining. Here is a picture. Engine is a OS 25FX on a mousse can and a 9x4 MA. I am turning about 18K RPM on the ground with this rig. All-up weight is 2lb 12oz - Super fun airplane to fly.

Almost all the planes flown in this class are short coupled, long wingspan airplanes. A wide flight envelope and high maneuverability are essential for good scores (Just like the big ones) Sharp high-G turning maneuvers, especially at high speeds, are a big edge on the competition.

I also have a Su-Do-Khoi and a Fun-51 I bash around as sport airplanes. I have been playing with flap mixing on all of these.

Keep the discussion going! This is good stuff.

Marty:

I beleive the short-coupled setup will inhibit the usefullness of flap mixing to the extent we do it on Unlimited Fun FLy ships. The elevator needs a lever arm to fight the flaps successfully. With a short-coupled rig, I think the mixed setup will act more like full-crow airbrakes. However, experiment with various amounts and see what makes the tightest loops.

Chuck

Chuck,

I'll hafta respectfully disagree. When I showed up with my new Morris the Knife at the field yesterday, an experienced flyer told me about his attempt to fly one with no flap mix. He had used up the entire 300' runway and couldn't get the thing off the ground. The Knife manual recommends 50% flap mix with elevator. I was afraid that would be too much to handle, so I set mine at 30%. On my maiden, with full up (low rates) it barely lifted off the ground. On the second flight I set it per the manual - 50%. After about a 4-5 foot roll I pulled back on the stick and it leaped off the ground and rocketed straight up. Wow!

The way the Knife rides on the landing gear, it will not lift off without some flaps. The combined flaps / elevator work to rotate the plane. The combo is just as effective in the air as it is on the ground. Short moments don't negate the effect.

Interesting. It was a rationalization, but possibly wrong.

Both planes we are talking about (Unlimted boom plane and Knife) have large airlerons comapered to the combat plane pictured. I wonder if that could be causing his troubles.

I do know that the "best" moment on the boom planes seems to be around 19.5-20", but "best" is relative to the job at hand. We need to balance stability with manueverability. For some events (fun fly vs unlimited) the current trend is to slightly longer moment to bring back some stability.

I also notice that the ailerons shown above do not extend into the thrust line like our two planes. This may affect the effectiveness as well.

Bottom line, try until it improves, and don't be afraid to get radical. You can always turn the mix off if it does weird things.

Chuck

Good rule of thumb for combat maneuverability is 1/3 of elevator throw for flaperons without losing to much airspeed.