Official Freewing F/A-18C Hornet 90mm EDF Thread

[jasmith41]

If you're getting oscillations, the gains are too high. First you'll need to determine which surface is oscillating, most likely it will be the ailerons as I've found those oscillate before the elevator and lastly the rudder. Gyro oscillation on the ailerons makes it waggle rolling left right and gets worse the faster you go. Since you said the gains are fixed and not adjustable, I assume you are not able to put gains on a TX knob to adjust in the air, which is not a problem. As I said, the oscillation will occur the faster the plane goes, so when it oscillates, if you slow down it should cease. If it oscillates at all speeds, then the gyro may not be the issue (loose control horns/rod/servo or even a bad servo). I would change the gains to 15/20/20, assuming it is the aileron surface and it only happens at higher speeds. Generally, the faster the aircraft and the larger the control surfaces will require lower gain settings. I'm kind of surprised you're getting oscillations at what I would consider low gain settings (is this on a spektrum RX or with a stand alone gyro) since I'm using at least double that on all my EDFs with no oscillations. I even have the spektrum RX's in my 60" Extreme Flight planes which have extremely large control surfaces, but with those I am flying a lot slower than an EDF and use gains in the 25% range, except in some stall mode settings with gains up to 70%, but then the aircraft is really not moving. Dial down the gains (only on the oscillating surface first), take it up and see how it goes.

Thanks Hugh - you confirmed what i thought i knew - lower gain was better for these edfs that go fast. On the F8, we determined that there is a lot of play in the aileron linkage i probably still need to fix. I'm also not good at figuring out how much expo I need, so some of he movement may be due to nervous energy (shaking hands) on the stick. The F5 porpoises a bit at high speed, more so than aileron rolling back and forth. Yes, i can put the gain on the knob. had it that way at first and then locked them in to see if i could adjust it out, but sounds like i need to put them both back on the knob and try that again. Thanks again. I appreciate it.

[Hugh Wiedman]

Thanks Hugh - you confirmed what i thought i knew - lower gain was better for these edfs that go fast. On the F8, we determined that there is a lot of play in the aileron linkage i probably still need to fix. I'm also not good at figuring out how much expo I need, so some of he movement may be due to nervous energy (shaking hands) on the stick. The F5 porpoises a bit at high speed, more so than aileron rolling back and forth. Yes, i can put the gain on the knob. had it that way at first and then locked them in to see if i could adjust it out, but sounds like i need to put them both back on the knob and try that again. Thanks again. I appreciate it.

That should work better on the knob, start at 100% and then dial it down until the oscillation is gone. The only bad part about the gains being on one knob, is as you dial it down, all three go down at the same time. If you have enough channels in your TX, the ultimate way to do it is have each of the 3 surfaces on a separate wheel and you can dial each one down as needed. I don't do that (although that's how the HH technicians determine just how much gain each surface needs on a new model). Don't have enough channels and man, that's a lot to think about and fiddle with while you're flying, way to much for me just trying to keep it in one piece. A flying buddy has that, but my brain/fingers are way too far gone to take that step. After you get it flying with no oscillations, then go back to fixed gains so you don't have to worry about inadvertently changing the knob or having it at the wrong place for each model.

If you're hands shake a bit, like mine (had it all my life, which is the only reason I'm not a brain surgeon and the more nervous I get the worse), I would try just a bit more expo. You do loose a bit of the sensitivity, but it may also take out any hand shakes. I use about 25-30%, which is substantial, and the expert pilots I know like to use 10-15% max when flying my aircraft. My 3D aircraft on extreme high rates use expos of 70%, which is actually recommended by the Extreme Flight manuals. It sort of acts like low rates with minimal stick movements, but then transitions into high rates as you increase the stick movements.

[jasmith41]

That should work better on the knob, start at 100% and then dial it down until the oscillation is gone. The only bad part about the gains being on one knob, is as you dial it down, all three go down at the same time. If you have enough channels in your TX, the ultimate way to do it is have each of the 3 surfaces on a separate wheel and you can dial each one down as needed. I don't do that (although that's how the HH technicians determine just how much gain each surface needs on a new model). Don't have enough channels and man, that's a lot to think about and fiddle with while you're flying, way to much for me just trying to keep it in one piece. A flying buddy has that, but my brain/fingers are way too far gone to take that step. After you get it flying with no oscillations, then go back to fixed gains so you don't have to worry about inadvertently changing the knob or having it at the wrong place for each model.

If you're hands shake a bit, like mine (had it all my life, which is the only reason I'm not a brain surgeon and the more nervous I get the worse), I would try just a bit more expo. You do loose a bit of the sensitivity, but it may also take out any hand shakes. I use about 25-30%, which is substantial, and the expert pilots I know like to use 10-15% max when flying my aircraft. My 3D aircraft on extreme high rates use expos of 70%, which is actually recommended by the Extreme Flight manuals. It sort of acts like low rates with minimal stick movements, but then transitions into high rates as you increase the stick movements.

Thanks again - i was thinking the same about all 3 gain levels moving if on one knob. I've got two open knobs and two open sliders on the ix20, so can split them up accordingly... I may try setting them all lower and adjusting from one knob, turning up the expo and see what happens. The porpoising on the F5 is real subtle, but it's there. The F8 is another story. How would you fix the loose linkage issue? It seems like the clevis pin is pretty loose in the arm coming off the wing. Should i glue the hole shut and re-drill it with a smaller hole...? or are there known tricks...? none of the clevises i have are any larger pin-wise... and these are pretty small since it's a very small plane...

[Hugh Wiedman]

It seems like the clevis pin is pretty loose in the arm coming off the wing. Should i glue the hole shut and re-drill it with a smaller hole...? or are there known tricks...? none of the clevises i have are any larger pin-wise... and these are pretty small since it's a very small plane...

I'm sure there are some tricks for those small clevises but I don't have any myself. I use ball links on all my control rods to reduce the play from using those plastic clevises. I also put rubber tubing on any clevises (like those usually found on gear doors) and the horns on the servos.

[Evan D]

JA, look closely at those horns and you'll find the outermost hole larger than the others. It is designed for a ball to be screwed there for planes that use ball links. On most of the FW planes they tell you to use the middle hole if using clevis links. Look at the instructions closely.

[jasmith41]

JA, look closely at those horns and you'll find the outermost hole larger than the others. It is designed for a ball to be screwed there for planes that use ball links. On most of the FW planes they tell you to use the middle hole if using clevis links. Look at the instructions closely.

yeah - switching the ailerons to ball-links - most logical thing to do. The style Hugh is showing i have on all the other FW planes, but this little F8 has the traditional 'clevis' design. Switching them all is the way to go to eliminate that as the cause of the weird movements while flying.

[Evan D]

I'm not saying that. I'm saying that the holes in the horns are different sizes and you use the smaller holes if using clevis's. Using the proper holes, per the instructions you shouldn't have any play.

[Evan D]

Look at the instruction manual...

[jasmith41]

Look at the instruction manual...

It's set-up per the manual, same as i do with all planes.

[Evan D]

But your clevis links are loose on your F-8?

Can you post a picture?

[jasmith41]

But your clevis links are loose on your F-8?

Can you post a picture?

yes and yes - later...
push rods are so small, i'm not sure there are ball links to fit them...

[jasmith41]

But your clevis links are loose on your F-8?

Can you post a picture?

In case you're not familiar with this model, there are only two servos - one on each side that control both aileron and elevator. Plane is set up as with elevons / tailerons. Was really odd for me with this one when just starting out because i have no other birds set up this way, but i think i've got my head around it - other than minor tweaks like this issue. The mudduck has one as well and he's set his ailerons to move as little as possible. I'm may have moved my ailerons down one from the book set up, but they were just as loose in the old setting.

[Evan D]

Yes you moved the clevis on the ailerons. Look at the second picture and see how the outer hole is larger? Using the clevis in this larger hole causes slop. Is that the slop you were asking about earlier saying you wanted to fill in the hole and redrill?

I am familiar with this set up and it works surprisingly well. It’s obviously not a way to rig a 3D airplane but…

[jasmith41]

Yes you moved the clevis on the ailerons. Look at the second picture and see how the outer hole is larger? Using the clevis in this larger hole causes slop. Is that the slop you were asking about earlier saying you wanted to fill in the hole and redrill?

I am familiar with this set up and it works surprisingly well. It’s obviously not a way to rig a 3D airplane but…

Thanks for the read.

The elevator, while in a 'smaller' hole, is still sloppy... as is the aileron, but it's in a 'big' hole - either one could cause the rocking the way they move...

Any idea what size pushrods those are and where i can find ball links small enough for them?

[Evan D]

There are choices. The stock rods are 1.2mm and there are some smaller ball links for other brands like Dynam, FMS and others but it would be hit and miss to find matching balls for the links.

Another choice is finding clevis’ with larger pins, probably the route I’d take…

Another choice would be sets you can get for the various FreeWing planes with larger rods that look like the ones in Hugh’s picture. With these you’d need to drill the servo arms a bit to accept the L bend. Buy long rods and bend the L where you need it.

[Evan D]

I went upstairs and looked in my stuff. What would you prefer to do? Maybe I can piece it together. Do you want larger clevis’ for the wire you have? Do you want the larger balls with larger wire?

let me know which way you’d like to go and measurements and maybe I can put that together.

[jasmith41]

I went upstairs and looked in my stuff. What would you prefer to do? Maybe I can piece it together. Do you want larger clevis’ for the wire you have? Do you want the larger balls with larger wire?

let me know which way you’d like to go and measurements and maybe I can put that together.

i've got an assortment of sh*t as well - i'm going to go thru it to see what i can find - i may just have the stock...
will advise... thanks in the interim.

[rcflyerct]

Hey guys got a basic battery question. I was thinking of trying a 6s 7000 in the bird that is a 30c, versus the 5,000 50c I am using now. My concern is if the 130A ESC...would this make the 50c better necessary? Thanks for the help!!! Wes

[Evan D]

Many C ratings are guestimates at best. The stock 6S pulls about 110A. I have 35C 5000's that don't sag or get hot pulling an occasional 110-115A. So bottom line it depends on the quality of your battery.

[Hugh Wiedman]

Hey guys got a basic battery question. I was thinking of trying a 6s 7000 in the bird that is a 30c, versus the 5,000 50c I am using now. My concern is if the 130A ESC...would this make the 50c better necessary? Thanks for the help!!! Wes

Agree with Evan D . I'm using an SMC 6200 40C (actual C tests out to 38-39) with the 12 blade inrunner and I pulling 126.8 Amps and 3190 Watts with fully charged battery. Guaranteed the batteries you are using probably test out to an actual C of maybe 60% of advertised (if that), so you have no issues to worry about with the 130 A ESC. Use the battery that gives you a combination of the longest flight time and best flying characteristics knowing that the lighter the weight the better it will fly, but also the less flying time, so you'll have to make a choice.