Need to apply left rudder during backward loops

[omerco]

Hmmmm now that you wrote that...it does look like there is power in the 8th port...

[rs2k]

Double Post.

[rs2k]

Thanks! I'll put the longer arm on.

Here's a better picture of the wires. Two ports are still open, one being io-d/e, the other being sw-a.

Power is being supplied to the port taking the governor input io-c or io-b (which ever one is the gov input, I can never remember) and the throttle port io-a(t). Power is being supplied to the Rx through io-b or io-c (which ever one is not the gov input). When I get my sk720 be, the port supplying power to the RX will be used as the sbus cable.

[omerco]

What is connected to ext-led port? Output to led?
That also is not a port to power

[rs2k]

I have the external LED input plugged into the LED output port. It's getting its power from the RX which is getting its power from IO-B which is currently only being used for power. The signal pin is removed from the servo connector before it gets to the RX. That will become my Sbus cable when I get the SK720 BE though.

I'm putting on a new servo horn as we speak.



Rundown:
All servo wire in this image is 22 gauge except for the EXT LED signal wire which is 24 gauge. I have a distinct arc in the cable for a good 3 plus inches to try and provide some vibration resistance. When running up drive train with main blades off the vibration I feel with my hand at the SK720 is as low as I've ever felt on any helicopter. All swash servos and tail servo wires are zip tied together about 3 inches from the SK controller. They go another 2 or so inches after that before they touch the frame.

Sat port closest to USB: goes to Sbus adapter. Red power cable on Sbus adapter is disconnected and does not enter the RX. Hot glue on end of connector to provide strain relief. I know t looks ugly.
Other Sat port: Not connected.
EX-LED: Extension goes to LED output
IO-D/E: Not used
IO-C: Extension goes to cable with: RPM output from ESC to signal, 8V+ and Ground directly from 2S Lipo.
IO-B: Goes directly to Y-Cable with Signal wire not connected. 8V+ and Ground go to RX for power on one end and 8V+ and Ground to 2S Lipo on the other end.
IO-A(T): Goes directly to Y-Cable with one end open to provide easy access for Castle Link (5V+ from USB is not connected so no power flows into SK-720 while using Castle Link) and one end going to ESC connection: Signal, 8V+ and Ground all attached. ESC does not have a BEC.
SW-A: No connection.
SW-L: Goes directly to the JR 8917HV CCPM servo.
SW-R: Goes directly to the JR 8917HV CCPM servo.
SW-C: Goes to extension which goes directly to the JR 8917HV CCPM servo.
Tail: Goes to extension which goes directly to the Outrage BL9188 HV Tail servo.
GPS Port: No connection since the SK-GPS flew through the tail during a blur piro.


RX has three wires running into it.
Spare bus port: 8V+ and Ground power from IO-B. (Will be replaced when SK720 BE comes). No signal wire connected.
Spare bus port: 8V+ and Ground to External LED. No signal wire connected.
Sbus Out: Goes to Sbus adapter. 4V+ is not connected.

[rs2k]

New horn gives these numbers: -4.2, 87.7, 111.6

I don't really like the angle that the tail linkage makes, but it's not binding and I always make sure the linkage guides are lubed. It doesn't look like it in the image, but there's plenty of room between the boom and the servo horn.



The picture makes it look like I could get my angle closer to 90. I'll try again with a carpenter's square a little later.

[omerco]

Great

[georgi UK]

=] I think in a hole and drop the RH to match the desired 100% LH,

[omerco]

In one hole gave 109 over 136. Please test with that and see how it goes. Lower your gain before flight and readjust in flight.

[rs2k]

Yup, in one hole does give 109/136. If it'll make a difference I can drill a hole in between on a cut down align servo arm to get closer to 100 on left. I don't think I'll get a chance to test fly until Saturday morning so I have time.

I'm guessing I'll be closer to 100 Left / 122 Right if I do that.

[georgi UK]

=] the point is, you can manually drop the RH ie, don't give it full travel, just make them equal. 109 either side says you have got the sweet spot....

[rs2k]

I'm afraid that will give me tail blowouts. I can already blowout the tail doing a flip at the top of a loop. Unless maybe it's caused by the tail stalling.

[omerco]

Originally Posted by georgi UK

=] the point is, you can manually drop the RH ie, don't give it full travel, just make them equal. 109 either side says you have got the sweet spot....

Me and Georgi have some historic disagreement on that

The way i fly if i dont use the full right trav i loose tail on hard combined maneuvers, so i give the whole travel and aim for as close as i can and if the sum is around 200 and points are close to 100 its good for me.

I've just tested my X7 with similar - 85/115 -numbers and for now it looks like it is better then the 105/120 i had before.

From my experience with Raptors - limiting right travel will give tail problems.

[rs2k]

Yes, I've read that Raptors need all the tail possible. I'll be getting the faster speed tail gears when they become available. That and the 116mm Rails I have should never get blowouts. I think the problem with the Raptors are that they are designed to run at 2100+ RPM, but they are so light they don't need anywhere near that.

I've read that some helicopters actually can have too much tail throw. I don't think any of my helis have ever suffered from that though. If they did I think a symmetrical setup would be great.

I think I'll start with a gain of 50 and go up from there. Once I get hunting I'll back down about 5 notches.

[omerco]

110 are more suitable i believe with original gears. If you change gears stay 105
That's for around 2100rpm

[rs2k]

I'm flying 1750 and 1850 most of the time. I've never had it higher than 1950. It does everything I want at 1650 to be honest, even fast (for me) tictocs, but I don't trust the tail down that low. I even did some light 3D at 1550 RPM on a a pair of 3700 MAH batteries. The heli sounds spooky at that headspeed with the cyclone main blades whisper whipping the air. I really look forward to trying out the faster tail gears.

I did some flying today, but it was really windy and the sun wasn't in a comfortable area for me. It was still needing left rudder after doing backwards loops so I slowly backed down the cyclic to tail mix until it got down to 0. It's much much better now, but it's still not perfect.

I currently have my collective to tail mix set to 25%. I think if I lower that down it will make the difference. I did notice it had an effect on backwards loops as well. The problem with changing that number is it will affect punch outs. 30% is a little bit too much. The tail swings to the left on a full collective climb during the initial power application maybe about an inch then swings back to center within a second. At 25% the tail swings maybe half an inch to the right during the initial application of power then it goes back to center within a second. How closely should the tail hold here? I think I'm going to need around 20% to backward loops perfect.

I was getting a tiny bit of hunting in fast backwards flight at 64% gain. I'm at 60% gain and have not heard it hunt once. I'm surprised because those are almost the same numbers I was getting before changing the arm.

[omerco]

Changing the arm can give "strange" gain results because there are more thing involved than its length like servo's accuracy and speed:

If your arm is short your servo reactes slower which effects the gain. Your numbers were way out of optimal and makes it hard on the gyro. Going longer should theoretically lower your gain - but you are at a better point which compensates for that.

On my 450 for examp i have the align servo which is 0.07 sec. I tried few length and got best redults at 75/90. All due to it beeing so slow. I have 60 gain now. When i had 110/120 it was 40...

Understood about the blades but still think you dhould try 110 as well. That + faster gears should do it i think? And if so will give you overall better result.

One more important thing - those helies are tail sensetive to the RPM changing on collective punch. You should fix your gearing and fine tune your governor and then redo the collective-tail mix.
What happens if you dont is: on punth outs rpm drops, causing you to increase the mix. That will cause overcomp on lighter maneuvers -like the one you describe

[Ah Clem]

I have run into this during backwards, outside loops on two different brands of FBL units on five different machines.

In each case, it was a precomp issue.

I was having to add left rudder as I pulled the machine through backwards outside loops.

In the case of the BeastX (on a Fusion 50), I just shut the precomp off and it corrected the situation (this machine seems not to need any precomp, for some reason).

In the case of the Mini-Titan, 6HV-U, Raptor 50, and Warp (all equipped with Robird units), I just turned the pre-comp down for both the collective and cyclic, until the ships tracked straight through the backwards outside loops.

I apologize that I have no experience with the Skookum units. I hope that what I experienced with the other two brands may translate to the Skookum (which I understand is a great unit).

[rs2k]

I'm not noticing the problem with the cyclic precomp set to 0 and the collective precomp set to 25. The tail kicks ever so slightly to the right at 25 when pushing the collective hard from a hover, but it feels good in other maneuvers. I'll have to check it out more when I can fly out at the field.

I also put the 12 tooth pinion on in place of the 13 tooth pinion and set the Gear Ratio to 53.33. The governor gain was a bit too high at 28 during my one flight today, but I could immediately tell the heli feels noticeably livelier at 1850 RPM than it used to and 1950 RPM feels very lively. It's not bogging as much and the climbouts feel stronger. Amp usage is down but motor and ESC temps don't seem any different, but they were already safe to begin with. I think it was a great change and will help with the tail issues at the lower RPM headspeeds.

This heli flies great at 1850 RPM. I'm considering getting an E700 V2 with the faster tail gears when it becomes available and gearing it for 1850 Max RPM on a 14S setup.

[omerco]

Great to hear!