Unofficial SK720 Resource, FAQ, & Compass 6HV Data. CC Phx ICE 100 SK720 (pg #72)

[Ice93]

Was thinking it would be good to start some sort of a FAQ/Resource Guide which would make looking for answers/tips & tricks more accessible and convenient.This will be a consolidation of tips & tricks as well as problems you have experienced while using the SK720. Hence, the more people participating in this, the better the guide/faq will be.

I am by far no expert in FBL and the 720, but I think this will be really beneficial to likes of noobs like myself

Disclaimer:
Try everything at your own risk, the author(s) will not assume any responsibility for any damages an/or malfunction to your equipment.

[Ice93]

Question:-
Do I need to use the power bus if I am running a regulator and/or external receiver?

Answer:-
No. However, using a powerbus will give you the advantage of consolidating all your servo wires and output the signals to just 4 wires. This will be extremely beneficial especially for nitro helis.

For futaba users, please refer to this link (Compliments of Skint Eastwood):
https://www.helifreak.com/showthread.php?t=212744

For Futaba users you can still use this wiring diagram even though you are using a regulator just cut off the red and black wires and use the jumper to connect both the LV and HV bus. I am currently using this setup.

[visionplay]

Question: With so many opinions, tapes, straps, plastic zeal insulated boxes etc:.....What is the best way to mount the SK720 on a Nitro Machine?

[Skint Eastwood]

Originally Posted by visionplay

Question: With so many opinions, tapes, straps, plastic zeal insulated boxes etc:.....What is the best way to mount the SK720 on a Nitro Machine?

_______________
[_720_Long side___}

__1/32 Solid Tape__

____Metal_Plate___

_______mm_______
SuppliedMMTape___

__________________
_____Heli Surface___
oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooYou basically want to mount the 720 on the metal plate with a solid layer of hard thin unmovable tape so the 720 and the metal plate become as one (in resonance terms)

Then use one piece of supplied vibration tape cut in half with one section on each end with a 1/4 " gape between.

This was Skookums last recommendation for Nitro, no need to use straps but if you are worried about the unit tearing off then use dental floss each end tied loosley

[tribe3]

I think this should become a sticky where we can also start adding basic setups that work for different brand/size of helis

[Skint Eastwood]

Stickied

[Ice93]

Originally Posted by visionplay

Question: With so many opinions, tapes, straps, plastic zeal insulated boxes etc:.....What is the best way to mount the SK720 on a Nitro Machine?

Here's how I did mine:-

[_720_Long side___}
__3M HD Tape_____
_Spartan Metal_Plate
__3M HD Tape_____
___SK Metal Plate__
_Black Spartan Tape_
_____Heli Surface___

Ideally it should be:-

[_720_Long side___}
__3M HD Tape_____
_2 x SK Metal Plate
_Black Spartan Tape_
__________________
_____Heli Surface___

Just use epoxy to glue the 2 SK metal plates together. I'm using the 1st method and it works just fine! You can take a look at the attached photo.

[Silverexpress01]

Question: What does oscillation look like?

Answer: see video for an example.

Just to clarify...

Bobbing ~ vertical oscillation, and usually there is a noticeable pivot point - like the swashplate.

Wagging ~ horizontal oscillation. Like a fishes tail, and not dolphins, whales or mermaids.

[ame]http://www.youtube.com/watch?v=fnvYKSpVww0[/ame]


Examples of issues regarding oscillation that has been posted:

https://www.helifreak.com/showthread.php?t=226593

A real good thread on D/R (TX), Expo (TX), and Advance Options on the SK-720:

https://www.helifreak.com/showthread.php?t=224651

[Skint Eastwood]

Heres an updated futaba wiring plan. The good thing about it is it has only 4 leads from the power bus to the 720.
I have to point out that i use this on my helis and have done for several months, but you do so at your own risk.

[Ice93]

Question:
Is that "SK720.CFG" file that is always present on the SD card the file that the unit loads to fly with?

Answer:
No. The unit needs a micro-sd card to connect to USB, but its flight file is not actually stored on the micro-sd card. In fact you can erase that file, and it'll just re-create it, no harm done. (Answer provided by Skookum)

Thread Reference Link:- https://www.helifreak.com/showthread...14#post2094214

[Ice93]

Question:
Does the "Auto Trim at Init." work the same way as the autotrim function in Mikado's V-bar?

Answer:
No. Auto Trim at Init" really is just there to correct for TX stick pot drift due to temperature changes, etc.. (Answer provided by R0t0R)

Thread Reference Link:-https://www.helifreak.com/showthread...=220070&page=2

[Skint Eastwood]

Heres a step by step guide to setting up bank switching on a 10c..
I have chosen to use chan 7 on my tx for the gain switch.

1. back up your model onto another model no. in your radio so you can come back to this if you messs anything up.
2. remove blades and disconnect motor if electric
3. go to the 'HOV-PIT' menu and make sure this shows 'MIX>INH'
4. go to 'HI/LO-PIT' menu and make sure both 'ADJ>' show 'ADJ>MANUAL VR>NULL
5. go to 'AUX-CH' menu and make sure 'CH7>NULL'
6. power up your heli with throttle hold on and connect up the sk720 usb and open software.
7. In software under 'GAINS' choose the 'SHOW FLIGHT GAINS MATRIX' option
8. on your TX goto 'PROG.MIX1-6' menu
9. goto 'PROG MIX 1' or a spare prog mix
10. setup the prog mix as follows
MASTER>VrA
SLAVE> CH7
RATE> +30%
MIX>ON
LINK>ON
SW>SwB (or a 2 position switch of your choice)
POSI>UP

11. goto 'PROG MIX 2 or a spare prog mix
12. Setup as before with these exceptions
MASTER>VrB
POSI>DOWN

13. goto 'GOVERNOR' menu
14. setup as follows
MIX>ACT
UP>75%
DOWN>25%
SW>B

-cut-
CH>-10 (or unused channel)

Now the gain in your heli is controlled by the 2 Vr knobs at the top of your Tx , when switch b is up you use the VrA when it is down you use the VrB.

In each bank you can choose in the 720 software which gain to control on the Vr knobs, either tail or cyclic.

make sure you tick the boxs in two cyclic and the two tail tabs in the 720 software to suit your choice.

One way would be to lock the gain in cyclic 1 and tail 2 , so that with switch B up you have control of the tail gain and with switch B down you have control of the cyclic gain. (make sure you have one 'LOCK GAIN' box ticked in either cyclic1 and tail 1 and also one in either cyclic 2 or tail 2)

16. Once you have decided which gain to control make sure both Vr knobs are centred and then looking at the 'GAINS USED IN FLIGHT' whilst in the 'GOVERNOR' menu alter the percentage for UP> and DOWM> until the gain you want is shown.
17. As you fly and turn the Vr knob to adjust gain. once you are happy with the gain remember at the gain amount in the 'GAINS USED IN FLIGHT' box then centre the Vr knob and adjust Governor as in 16.

[Silverexpress01]

Question: What is the advantage to a flybarless setup vs. fly barred?

Answers:

https://www.helifreak.com/showthread.php?t=100553

---------------------------------------------------------------------------------------------------
Credit goes to the original author:

Flybarless rotor Heads - The RC Ins and Outs

What was the flybar for anyway?
The flybar performs three basic functions – stabilization, amplification of cyclic input, and resistance to pitch up in forward flight.

1. Stabilization: While hovering a wind gust may try and move (tilt) the main rotor. The flybar will be differently (less) affected, and the linkage system will adjust the pitch on the blades to resist the change.
2. Amplification of cyclic input: When the swashplate tilts and moves the flybar, aerodynamic forces imposed by the flybar paddles change the spinning plane of the flybar, and again through a series of linkages this then changes the pitch on the main rotor blades. This means the servos work less hard to achieve a cyclic input.
3. Resistance to pitch up in forward flight: In fast forward flight the blade advancing into the airflow creates more lift than the blade retreating in the airflow. This causes a pitch up motion of the helicopter. The flybar again tries keeping in its own plane of rotation, and through the linkage system adjusts the pitch on the main blades to resist this change.

So the electronic components of a flybarless system take over these tasks from the flybar.

So why ditch the flybar and change to a flybarless head setup?

Flybarless helicopters have arguably better all round aerobatic performance. But they are also great for scale models, aerial photography platforms, etc.

Advantages include:
* Less rotating mass
* Lower drag
* Combination of longer flight time and better 3D performance
* Less mechanical complexity
* Multi blade rotorheads
* Infinitely ‘tunable’ flight characteristics, including improved stability if desired
* Looks cool!

What is required:

1. The Flybarless Head Itself – It is ideal to purchase a custom designed flybarless head for your size of helicopter rather than try and modify an existing setup. There are several reasons for this:

• The geometry of the head is important
• You are purchasing a product that is known to work

2. Flybarless Electronics – You require a system to take over the role of the flybar. There are two and three axis units on the market. For general flying a two axis unit (meaning you still require your own tail gyro) works very well. For 3D flying there are advantages of three axis units, however the two axis ones still hold their own.

A two axis unit essentially contains two heading hold gyros (left/right and fore/aft cyclic). A three axis unit adds a tail rotor gyro also. Much like the way a traditional tail rotor heading hold gyro works, the cyclic gyros have the ability to stabilize the rotor head from wind gusts, etc.

It is possible to fly a flybarless helicopter without electronic stabilization. However, the task is much easier with the help of an electronics package. You would not fly your helicopter without a tail gyro, would you?

3. Servo Selection – Fast digital servos are preferable. But again, depending on your flying style,any reasonable servo will allow you to experience the flybarless feel.

In Flight Flybarless helis can be set up to behave in an almost unlimited number of ways. With a flybar, it was time consuming (and expensive) to try a variety of flybar lengths, different paddles, blades and flybar weights.

With the ‘electronic flybar’ it is simply a matter of changing some of the programmable parameters in the unit itself and you have a whole new feel to the helicopter.

There are some further flight differences with a flybarless heli. The cyclic controls now command a cyclic rate’ from the rotor head. So if the helicopter is on the ground and even a small cyclic command is held, the cyclic servos may move hard over to try and achieve the commanded cyclic rate. So it is important not to add cyclic control until the helicopter has lifted off.

Autorotation performance is overall improved, but somewhat of a different technique is required to realize this increase in performance.

Article Source

http://www.collectibles-articles.com

--------------------------------------------------------------------------------------------------------------------------

A thread on flybarless with no electronics.

https://www.helifreak.com/showthread.php?t=165085

A video of a 200 size heli that is flybarless with no electronics (many more on youtube)

[ame]http://www.youtube.com/watch?v=BK9X_Ro6AjY[/ame]

--------------------------------------------------------------------------------------------------------------------------------------
A real good example of the flexibility that software and an onboard processor can provide....

The following thread is from a gentleman who is building his own FBL unit. Recently he successfully programmed it so that the phase was off by 45 deg. This is to my understanding a virtual flybar setup like that of a mechanical flybar that is 45 deg offset - Blade MSR, CB100..etc. This is a mechanical rotor head that is known to be stable. In fact, it maybe too stable.

The virtual flybar made by Heli Hacker

A video of his heli and DIY phubar fbl unit with 45 degrees phasing:

[ame]http://www.youtube.com/watch?v=XNDqIA-uyUc&feature=player_embedded[/ame]

You would need the skills and talents of a machinist if you wanted to accomplish the same thing mechanically.

At this time, I have not tried a 45 deg offset with the SK-720 myself. (Planning on it though - it may or may not work. The software being the limitation of which I have no control unlike Heli Hacker)

Update 8/12/10: I tried a phase setting of 45 deg, and it worked somewhat. I prefer Self Leveling with low D/R's and a bit of expo thrown in if I want my Trex 250 to be docile and boring.

A link to his project:

http://code.google.com/p/phubar/

[Silverexpress01]

Question: What is the difference between HH (Head Holding) and Rate mode in regards to my tail gyro?

Answer: In Head Holding mode the gyro will bring the heli back to an initial heading after it has experienced a disturbance.

In Rate mode the gyro will dampen the motion of the tail to a stop after you've moved it. It will not correct for strong disturbances.

Here is a krazy video that shows the difference (don't try this with your 600!!!!)

[ame]http://www.youtube.com/watch?v=NzBgRe5u7K4&playnext_from=TL&videos=Ch7Iei lHLlI[/ame]

[Silverexpress01]

Question: How do I get a hold of Skookum with an Issue?

Answer: email them at info (@) skookumrobotics dot com - format changed to avoid spammers. State your issue, and attach your heli's current profile file.

[Silverexpress01]

Question: How do I remove the microSD card from the unit?

Answer: Here is a tip, and pay special attention to the additional info provided. The sd card is located deep below the center set of servo connection pins.

"It's possible to (carefully) remove the micro-sd card using a very small tip flat screwdriver or a dull #11 exacto blade tip. You could then either format it with an adapter on your PC, or replace it with another 2gb card. You'd have to rename the card SK720 by (right-click it in windows explorer) before it will be recognized though.

NOTE: If the micro-sd card is in the unit, format it using the SK720's software, not using windows!"

- Skookum

User Experience:I found it difficult to extract. I ended up using two dental picks, and using the tips I carefully nudged the microSD card side to side and at the same time pulling it forward with friction till it fell out. I used two damping pads that sandwiched the SK-720 and held it in a vise with gentle pressure, since holding it by hand was very difficult during the process.

Note: I flattened the ends of the dental pick, so they looked somewhat like flat bladed screwdrivers. The original points presented a surface that was too tiny that would slip off the side of the SD card. Removing the microSD is not something you do normally. The original SD card used is of good quality.

[f22warzone]

Question: What Format is the Sk 720 Card in

Answer: It is in the FAT or FAT16 Format, any other will not work.


Stock Sk 720 Profiles in case you were to format your computer or loose the Original.
https://www.helifreak.com/attachment...0&d=1281013619

[Silverexpress01]

Question: Ugh! My case is cracked!

Answer: https://www.helifreak.com/showthread...25#post2261625

[Skint Eastwood]

https://www.helifreak.com/showthread.php?t=235084

[Silverexpress01]

Question: Ugh my USB port stopped working, what now?

Answer: The first units to go out had issues with the soldering of the USB recepticle on the circuit board. This results in a unit that is undetected by your PC, but the problem may be intermittent.

If caught early, you should be able to exchange your unit via the vendor. If it is out of the return policy window then you'll have to send it to the manufacturer. Contact info for Skookum Robotics is as follows:

Return Address:
Skookum Robotics

PO Box 46912 Stn D
Vancouver, BC
V6J 5M4 Canada

Email:

info @ skookumrobotics.com or
tech @ skookumrobotics.com
(Remove the spaces)

For return shipments, be sure to write Warranty Return on the outside of the package your shipping and on the customs form.