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HomeAircraftHelicopterMain Discussion › Multiple Forward Flips - How to add a mix???
06-07-2009 11:15 PM  9 years agoPost 1
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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So the pros can do multiple forward flips down on the deck, in exactly the same spot, and the heli looks like it is turning in its own diameter.

I can do multiple forward flips on the sim, and if/when I get the timing & collective perfect, I can sit there and knock them out one after the other after the other.

But with the real bird the thing I have the most problem with is the nose. After about 2 or 3 flips, the nose has turned to the right by 45 degrees to as much as 90 degrees when I stop the maneuver.

So, I'd like to tackle this with a mix. But I've never used a mix before.

How do I set up a mix on my JR 9303?

What would the mix be (Elev to Rudd or Rudd to Elev?)

How much of a percentage should I try?

Thanks

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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06-07-2009 11:20 PM  9 years agoPost 2
FlaG8r

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Florida

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I don't think you need a mix...I think the problem is you're feeding in too much rudder unintentially. Try upping your expo on the rudder channel.

Life is tough, it's tougher if you're stupid

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06-07-2009 11:38 PM  9 years agoPost 3
Yug

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UK. Herts

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Could be caused by a number of things such as gyroscopic precession errors due to inadequate mounting or even just phasing.
How does your heli behave when doing continous back flips or rolling circuits ?

Vegetable rights and Peace

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06-08-2009 12:09 AM  9 years agoPost 4
QuantumPSI

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Atlanta, GA

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Yeah this particular issue is hard to track down. As Yug said, it could be a number of things. I'd check your gyro and rudder setup first and make sure that that's operating 100% correctly. Then I'd check phasing and use the appropriate mixes. For a long time, I had a similar issue and thought that my tail just wasn't set up right and I would always try to correct with rudder and things always got a little awkward, acceptable, but awkward nonetheless. Eventually, I started playing with some phase mixes and now my machines fly straighter than they ever have.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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06-08-2009 02:45 AM  9 years agoPost 5
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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Eventually, I started playing with some phase mixes and now my machines fly straighter than they ever have.
Well, umm, so I have a question - how do you do a mix???

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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06-08-2009 04:14 AM  9 years agoPost 6
Mike Fortin

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USA

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No mix needed, just practice.

Have Rotors, Will Fly!

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06-08-2009 04:33 AM  9 years agoPost 7
jschenck

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La Vista, NE.

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Eventually, I started playing with some phase mixes and now my machines fly straighter than they ever have.
Well, umm, so I have a question - how do you do a mix???
Phase mix is a mechanical mix, usually the ring right under the main head hub. That ring usually has the two guide pins for the washout assembly to ride. Moving this a little one way or the other changes the swash to mixer 'timing' which can remove (or add) side cyclic and fore/aft cyclic interaction.

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06-08-2009 04:59 AM  9 years agoPost 8
Fastsrt

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Lebanon, Tn

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By looking at Rocks' gallery he isn't flying a heli that have any phase mix adjust capable helis. Trex's and N9's do not have an adjustable setup.
I have the same problem but it's my thumbs and fingers.

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06-08-2009 05:16 AM  9 years agoPost 9
QuantumPSI

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Atlanta, GA

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No mix needed, just practice.
This isn't always the case. Not all helicopters have the correct phasing built in mechanically.
Phase mix is a mechanical mix, usually the ring right under the main head hub. That ring usually has the two guide pins for the washout assembly to ride. Moving this a little one way or the other changes the swash to mixer 'timing' which can remove (or add) side cyclic and fore/aft cyclic interaction.
Not all helicopters have this adjustment and looking at Rocko's profile, I know that those particular machines do not have the necessary adjustment.

You need to go into your 9303 and program 2 mixes. Aileron -> Elevator and Elevator -> Aileron. Now the values you need and directions will have to be found experimentally. Do this on a calm day as the wind will effect your observations. Take your machine up and do a backflip to inverted. Observe what direction you have to input on aileron to level it out. Do the same thing but do a front flip this time. The directions you have to input to level it out should be opposite. So if you did a backflip and needed right aileron, then you SHOULD need to input left aileron when you do a front flip.

Now, go into your 9303 and go to the mixing menu. Setup a simple mix for elevator to aileron. Use EXTREME values for this (do not fly it like this). This is just to observe the direction of the mix. (You need to know if positive or negative values correspond to the direction you want). Once you've figured this out, start with a low value and get the directions correct (left when you input forward and right when you input backward or vice versa). Take the machine up and do the backflip and frontflip again. Observe what happens. Keep increasing the mix until the machine is level when you do the flip.

Once you have fixed the elevator -> aileron take note of the values and use them in the aileron -> elevator mix. You'll have to take note of the direction again. If you had to give right aileron when you do a backflip, you'll have to give forward elevator when you give right aileron. You should be able to figure out the other directions depending on the situation you're actually experiencing. Now, if your machine is setup properly, the endpoint values of the two mixes should be the same. Test fly your machine and adjust accordingly. Hope this answers your questions!

Edit: After re-reading your post, make sure your rudder is behaving 100% correct before doing the phase mixing I suggest up above.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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06-08-2009 01:36 PM  9 years agoPost 10
TDriver

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Portage IN

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QuantumPSI:

Great info

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06-08-2009 05:47 PM  9 years agoPost 11
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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QuantumPSI,

Thanks! You're the man!

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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06-08-2009 06:33 PM  9 years agoPost 12
Sam2b

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Tacoma, WA

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Good info indeed. Given that your swash is truly level throughout the entire collective range and that the swash linkages are rid of slop, the tail is the other factor to keep flips & rolls perfect. Tail gyro's are still not perfect, unfortunately. If the tail deviates the slightest bit and/or if you don't start the flip perfectly straight, the oblong flip or rolls will manifest.

You and add a Pmix to add a hint of right rudder during positive and negative collective movements. Play with it on the work bench and confirm the input direction before you fly. There's a chance this might help out. The Pmix would input a hair of right rudder preemptively counteracting what the gyro might be lagging behind in correcting the tail. This is likely the same input one would input to correct the tail manually while doing these seemingly perfect flips and rolls. Credit to the pilots.

_Sam B_

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06-09-2009 12:22 AM  9 years agoPost 13
jtg13

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So Cal

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Just a note, if this is an issue with the Trex 600 make sure you have the new swashplate/washout upgrade that fixed phasing errors in the original design. If you don't have white writing on the top of the swashplate you have the original design that had phasing errors that would cause this behaviour. This is only for the Trex 600 though. If you're experiencing this on a different model, after looking carefully for setup problems, follow the excellent PMix setup instructions from QuantumPSI.

John G

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06-09-2009 12:34 AM  9 years agoPost 14
Rockohaulic

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Canyon Country, CA, USA, 3rd Rock from the Sun

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I think I have the QUK swash on this 600N bird. I'll check when I get home......................

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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06-10-2009 06:27 PM  9 years agoPost 15
PC12DRVR

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USA

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Mike Fortin is correct, you don't need a mix, just set it up correct and practice. Too many people overcomplicate flying these helicopters

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06-10-2009 07:18 PM  9 years agoPost 16
Melon

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California

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If you find the nose moving you need to correct it by moving the tail in the opposite direction. You can make the helicoptet travel away from you as well as twords you just by controlling the tail when doing constant flips.
Practice! When you see the pros do it you only see the helicopter, not the sticks!

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06-11-2009 02:53 AM  9 years agoPost 17
QuantumPSI

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Atlanta, GA

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Mike Fortin is correct, you don't need a mix, just set it up correct and practice. Too many people overcomplicate flying these helicopters
No amount of practice will make a helicopter flip straight/roll straight. Yes, you can correct for its errors, but that doesn't change the fact that it doesn't do it perfectly. Phasing is more than just a setup and/or practice problem. It's the result of the dynamics of the rotor head.

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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06-11-2009 04:00 AM  9 years agoPost 18
PC12DRVR

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USA

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No amount of practice will make a helicopter flip straight/roll straight.
Thats a good one...

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06-11-2009 04:47 AM  9 years agoPost 19
TMoore

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Cookeville, TN

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No amount of practice will make a helicopter flip straight/roll straight. Yes, you can correct for its errors, but that doesn't change the fact that it doesn't do it perfectly. Phasing is more than just a setup and/or practice problem. It's the result of the dynamics of the rotor head.
Sorry but Mike Fortin is correct. Adjusting the phasing angle for flips won't necessarily make it roll straight and vice versa. Ask folks like Cliff Hiatt and Wayne Mann and they will tell you the same thing. Making a rotor head work for certain flight regimes is a compromise. I do flips on the deck all the time in one spot and it takes practice not to induce unwanted motion into the rotor head.

Stationary roll flips aren't the same as rolling at speed, same for loop flips and loops at speed.

The sim is great for learning orientations, the rest takes place at the field. The only way to bridge the gap between the sim and the field is to burn lots of fuel. Using a swash mix to tune a perceived flip interaction is a poor use of the mix and only covers a very small part of the helicopters flight capabilities.

TM

Delayed Response Operator Not Engaged
AMA SECTION 336 = Good
Drones = EVIL

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06-11-2009 05:14 AM  9 years agoPost 20
drdot

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So. California, Orange County.

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fwiw..

One thing that nay help is adding a littlt more tension to the centering spring on the rudder in the tx....Try that, add about 20% expo to rudder...Then burn a lot of fuel....

John.

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HomeAircraftHelicopterMain Discussion › Multiple Forward Flips - How to add a mix???
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