SK720 first impressions and comparison to an HC3SX

[Stanley Speel]

Hi,

I have just had my first flight with my Logo 400 (that wasn't in the garden), with an SK720. I just thought I'd share my initial impressions with it, and how it compares to a HC3SX. I will probably do a more detailed comparison in a few weeks. No governor was used on either heli.

As a lot of you probably know, I'm still learning, so I can only really cover their performances with piros, ff, hovering and circuits etc.

The HC3SX was on an MSH Protos; I haven't tried it on the logo, as it's going on my Trex 600.

Manual and Setup:

-HC3SX

I'll start with the HC3SX. The manual is probably the most poorly written thing I've read. It is very hard to follow and a lot of the wording is very vague. It has a setup wizard, which is a slight improvement over the manual, but still hard to follow at times. Setup for the Protos including the wiring etc took me about 2 -3 hours.

It seems that the manual is well known for how poor it is on HF, and some people are not buying it due to how complicated it is to set up. I am currently rewording the manual of the HC3SX which should hopefully make it a bit easier to set up.

-SK720

This was very easy to set up, with a clear and well-worded manual. Anything that I didn't understand was explained in even more detail in the setup wizard, which made the whole setup and wiring only take about 1-1 1/2 ours. The SK720 really does have an advantage over the HC as far as setup is concerned.

Hovering

-HC3SX

This was extremely stable while hovering, allowing for nearly hands-off hovering (normal mode of course). Out of the BeastX (v2), SK720 and HC3SX, the HC definitely feels the most 'locked in'. The tail held extremely well, and it wouldn't drift even with quite a lot of wind on one occasion.

-SK720

Again, very stable while hovering, and the tail also held really well. This was on a flat 0-100 throttle and pitch curve. However, when I switched to a more aggressive throttle curve, sometimes the tail would wag uncontrollably, even after I adjusted the gain. I will have to try and sort this out, as I tried gain settings from 45-60 and they didn't have much effect.

Piros

-HC3SX

OK the tail is probably the best thing about the HC3SX - it will do stationary piros until it's almost a blur, and as soon as you centre the rudder stick it stops instantly - holds rock solid. I really do not think this could be improved on at all.

-SK720


Also very good in most cases, but again, at a higher headspeed it would 'stutter' a bit when the rudder stick was centred.

Forward Flight


Forward flight for me is about 7-12 mph, so I can only comment on that . Both worked equally well here - the tail didn't drift or anything, and with the SK720 there wasn't any wag when using the 0-100 flat throttle curve. However I probably am not pushing them anywhere near hard enough for any tail issues to become evident though.

Self Leveling/Bailout

-HC3SX

The self leveling on the HC3SX is amazing. I was using the standard "normal+inverted leveling mode (so it doesn't control the pitch). The second I activated the self-leveling it instantly leveled the heli - no delay/vibrations etc... just completely level in less than a second.

-SK720

From my two flights where I tried the bail out mode, unfortunately it just didn't work for me. I first tried the CS+inverted mode in the garden, which supposedly should level the heli when the cyclic stick is released. It just behaved exactly like it would if it was off, and made no attempt to level the heli.

I then changed it to "on+inverted" mode when I flicked the switch (aux 4 I think), and also increased the leveling power or whatever it's called. I tried it about 5 times at the park, and 4 out of the 5 times it would slowly nearly-level itself, but it was always off by a bit. The other time it actually leveled it perfectly, but like the other times this took a few seconds.

I hope that I can adjust it in the software so that the self-leveling works better and fasted, as I bought it over a BeastX mainly because of the bail-out mode. If it still levels this slowly then I think it is quite pointless, as I would have probably crashed before it managed to level it.

Conclusion

I have kept this comparison brief as not only will I probably be doing a more detailed one in a short while, but also I haven't really flown the Logo with the SK720 much yet.

I would say that the HC3SX is definitely the better unit from how they flew so far. The HC is only about £30 more than the Skookum if you buy the HC3Xtreme from Heliguy for £200, and then send it to Captron to be upgraded to an HC3SX for around £150. It took about 2 weeks for mine to come back from them after they received it.

If you are willing to spend the extra hour or two deciphering the instructions of the HC3SX (not for long hopefully after I've rewritten them ), then I would certainly get the HC3SX over the SK720 - it is a better-built unit; the self leveling has been faultless; it doesn't have any vibration problems (which can't be said for my Skookum as I think that's why I'm getting the tail wag at a higher headspeed); and if my very limited flying-ability is anything to go by, performs much better too.

Of course this is only my opinion, and based on what I was looking for in a FBL controller. However, if you are looking for an easier setup, and think that the GPS add-on will ever be released, then you may find that the SK720 is the better unit.

I hope this helps a few people, and look out for the full reviews on them!

Thanks

Stanley

[steve b]

Nice right up Stanley i have the HC3sx on my t rex 700 and was a nightmare to set up first time
i have a english version of the set up video if any good to ya still a bit vague

[Stanley Speel]

Thanks Steve - I've got the hang of the setup now. I'll see what Joachim thinks about the manual when I've finished editing it - it can't be worse than what it was

[highsidenz]

Finding same thing on Compass Atom 500

Hi,

I have just had my first flight with my Logo 400 (that wasn't in the garden), with an SK720. I just thought I'd share my initial impressions with it, and how it compares to a HC3SX. I will probably do a more detailed comparison in a few weeks. No governor was used on either heli.

As a lot of you probably know, I'm still learning, so I can only really cover their performances with piros, ff, hovering and circuits etc.

The HC3SX was on an MSH Protos; I haven't tried it on the logo, as it's going on my Trex 600.

Manual and Setup:

-HC3SX

I'll start with the HC3SX. The manual is probably the most poorly written thing I've read. It is very hard to follow and a lot of the wording is very vague. It has a setup wizard, which is a slight improvement over the manual, but still hard to follow at times. Setup for the Protos including the wiring etc took me about 2 -3 hours.

It seems that the manual is well known for how poor it is on HF, and some people are not buying it due to how complicated it is to set up. I am currently rewording the manual of the HC3SX which should hopefully make it a bit easier to set up.

-SK720

This was very easy to set up, with a clear and well-worded manual. Anything that I didn't understand was explained in even more detail in the setup wizard, which made the whole setup and wiring only take about 1-1 1/2 ours. The SK720 really does have an advantage over the HC as far as setup is concerned.

Hovering

-HC3SX

This was extremely stable while hovering, allowing for nearly hands-off hovering (normal mode of course). Out of the BeastX (v2), SK720 and HC3SX, the HC definitely feels the most 'locked in'. The tail held extremely well, and it wouldn't drift even with quite a lot of wind on one occasion.

-SK720

Again, very stable while hovering, and the tail also held really well. This was on a flat 0-100 throttle and pitch curve. However, when I switched to a more aggressive throttle curve, sometimes the tail would wag uncontrollably, even after I adjusted the gain. I will have to try and sort this out, as I tried gain settings from 45-60 and they didn't have much effect.

Piros

-HC3SX

OK the tail is probably the best thing about the HC3SX - it will do stationary piros until it's almost a blur, and as soon as you centre the rudder stick it stops instantly - holds rock solid. I really do not think this could be improved on at all.

-SK720


Also very good in most cases, but again, at a higher headspeed it would 'stutter' a bit when the rudder stick was centred.

Forward Flight


Forward flight for me is about 7-12 mph, so I can only comment on that . Both worked equally well here - the tail didn't drift or anything, and with the SK720 there wasn't any wag when using the 0-100 flat throttle curve. However I probably am not pushing them anywhere near hard enough for any tail issues to become evident though.

Self Leveling/Bailout

-HC3SX

The self leveling on the HC3SX is amazing. I was using the standard "normal+inverted leveling mode (so it doesn't control the pitch). The second I activated the self-leveling it instantly leveled the heli - no delay/vibrations etc... just completely level in less than a second.

-SK720

From my two flights where I tried the bail out mode, unfortunately it just didn't work for me. I first tried the CS+inverted mode in the garden, which supposedly should level the heli when the cyclic stick is released. It just behaved exactly like it would if it was off, and made no attempt to level the heli.

I then changed it to "on+inverted" mode when I flicked the switch (aux 4 I think), and also increased the leveling power or whatever it's called. I tried it about 5 times at the park, and 4 out of the 5 times it would slowly nearly-level itself, but it was always off by a bit. The other time it actually leveled it perfectly, but like the other times this took a few seconds.

I hope that I can adjust it in the software so that the self-leveling works better and fasted, as I bought it over a BeastX mainly because of the bail-out mode. If it still levels this slowly then I think it is quite pointless, as I would have probably crashed before it managed to level it.

Conclusion

I have kept this comparison brief as not only will I probably be doing a more detailed one in a short while, but also I haven't really flown the Logo with the SK720 much yet.

I would say that the HC3SX is definitely the better unit from how they flew so far. The HC is only about £30 more than the Skookum if you buy the HC3Xtreme from Heliguy for £200, and then send it to Captron to be upgraded to an HC3SX for around £150. It took about 2 weeks for mine to come back from them after they received it.

If you are willing to spend the extra hour or two deciphering the instructions of the HC3SX (not for long hopefully after I've rewritten them ), then I would certainly get the HC3SX over the SK720 - it is a better-built unit; the self leveling has been faultless; it doesn't have any vibration problems (which can't be said for my Skookum as I think that's why I'm getting the tail wag at a higher headspeed); and if my very limited flying-ability is anything to go by, performs much better too.

Of course this is only my opinion, and based on what I was looking for in a FBL controller. However, if you are looking for an easier setup, and think that the GPS add-on will ever be released, then you may find that the SK720 is the better unit.

I hope this helps a few people, and look out for the full reviews on them!

Thanks

Stanley

Hi Stanley
I've just taken my HC3SX off and put a Skookum on my CA500 and I do can't believe how intollerant the SK720 is to vibration.
On my second flight I was trying the SL feature, to compare to the HC3SX, when it shut itself off and caused a great deal of concern.
I for one am going back to the HC3SX and will sell the SK720.
No where near the product of the HC.
Cheers
Phil

[Stanley Speel]

Just a small update on the SK720:

I flew 8 batteries on the logo today. The tail problem won't go away, and now when I use my 3300mah lipos it tilts to the left, and when I land it gives the vibration warning.

Even with the 2650s, when I climbed (increasing the HS), again, it would tilt to the left and I'd have to land it, and again it would give the high vibration warning.

Finally, even after a lot of tweaking on the software, the bail-out is still as crap as ever. I think the SK720 will be going up in the FS section, and I'll get a BeastX or another HC3SX.

[GetToDaChopper]

i own both and i couldn't agree more with your assessment as it is spot on the money and at the same time lacking any bull what so ever !

[chenliforum]

I have both sk720 and hc3sx. Bail out and self leveling work on both controllers.

I agree that HC3SX is overall a better system. But I also believe that it is unfair to just say that sk720 self-leveling and bail out doesn't work.

[CageyH]

Nice write up Stanley. I'll be interested in seeing your English version of the manual.
My HC3-SX took hours to set up, and I needed some help from the supplier to get it done.

Has anybody done a comparison between the Brain and the HC3-SX?
i want another FBL controller for my Protos which has self levelling, as this has kept my wallet fatter than normal when flying my Compass Atom 500.

[Stanley Speel]

Re: SK720 first impressions and comparison to an HC3SX

Nice write up Stanley. I'll be interested in seeing your English version of the manual.
My HC3-SX took hours to set up, and I needed some help from the supplier to get it done.

Has anybody done a comparison between the Brain and the HC3-SX?
i want another FBL controller for my Protos which has self levelling, as this has kept my wallet fatter than normal when flying my Compass Atom 500.

Send me a pm with your email I'll send you a copy.

It's a nice day today might get a video up of the bailout on the 450

[Snaaakeey]

Re: SK720 first impressions and comparison to an HC3SX

I ran a 720 on my 7hv all year this season with no probs what so ever. Vibration score of 2 raising to 5 or 6 in hard moves. 4 point and piro tic tocs could sometimes turn the sl off but thats not really what the sl feature is about. Ic helis have higher vibs but with the double plate mount there shouldnt be a prob. The vibe analysis is the best on the market bar none. Use it to track you vibe issue down and rectify it. You heli should run as smoothly as possible regardless of application. For example (REGARDING VIBE GRAPH)on the 7hv 2000 or 4000 rpm is something on the head. 10000ish is tail and 20000ish is motor. Find out whats your issue and iron it out. In this hobby there is no such thing as a plug and play solution. My mate ran the heli command. It had more or less the same issues as the sk. Infact after prolonged rolls/flips it seemed to get more confused than the sk and would continued holding the roll ( I have seen the sk do this too) apparenty the vortex will be more or less immune to vibs. Great for no hassel flying but your heli will probably be shaking itself apart on the quiet and the 1st you'll know about it is when it falls out the sky. Swings and roundabouts. These isnt a unit on the market that can see the difference between harmonic resonance and correct date stream yet. I would say they are on a par with each other really.

[Stanley Speel]

I ran a 720 on my 7hv all year this season with no probs what so ever. Vibration score of 2 raising to 5 or 6 in hard moves. 4 point and piro tic tocs could sometimes turn the sl off but thats not really what the sl feature is about. Ic helis have higher vibs but with the double plate mount there shouldnt be a prob. The vibe analysis is the best on the market bar none. Use it to track you vibe issue down and rectify it. You heli should run as smoothly as possible regardless of application. For example (REGARDING VIBE GRAPH)on the 7hv 2000 or 4000 rpm is something on the head. 10000ish is tail and 20000ish is motor. Find out whats your issue and iron it out. In this hobby there is no such thing as a plug and play solution. My mate ran the heli command. It had more or less the same issues as the sk. Infact after prolonged rolls/flips it seemed to get more confused than the sk and would continued holding the roll ( I have seen the sk do this too) apparenty the vortex will be more or less immune to vibs. Great for no hassel flying but your heli will probably be shaking itself apart on the quiet and the 1st you'll know about it is when it falls out the sky. Swings and roundabouts. These isnt a unit on the market that can see the difference between harmonic resonance and correct date stream yet. I would say they are on a par with each other really.

I will write a bit more of a longish update in the evening.. in short though as FBL controllers I have found they perform about the same.

With the SL there is no comparison - the SK720 is pretty slow to level (this was in my old 450 pro where there were no large vibes) and it doesnt climb either. Maybe on the new firmware where you can turn SL up to 200% this may have improves.

Currently on my 450 the HC3SX is flawless apart from a slight tail problem - think that the tail shaft is a bit bent. The SL works perfect every time. However on helis with huge vibes (such as my 600 with an unbalanced 600mx ) be warned that the bailout can become an auto crash

[Snaaakeey]

Re: SK720 first impressions and comparison to an HC3SX

Wow! Your running firm ware thats over a year old! Mine would sl at the maximum roll rate the heli could achive. Horizontal to flat or invert flat in 0.5-1 sec. I seriously suggest getting the latest firmware before formulating an opinion. The 720 really is cracking and there have been loads of add ons and upgrades since last year! I lost tx power in august and the 7hv went into auto land ( newish update). It suddenly went dead flat with 3 degs negetive pitch and 0 throttle. I expected at least a tip over as the unit doesnt know were the floor is but I lucked out and it landed fine just like a heavy auto from 50 foot up. All your issues may vanish after an update as they do sound like variouse bug fixes which have been implimented over the year. Dont give up just yet. I have been involved with 4 other units on different helis and once tuned in they have all been bomb proof.

[ModelGuard.Com]

maybe you havent got enough cyclic pitch going on there, the Sk720 should level out in an instant. This is 100% on a scale that goes to 200%. I flick the self level switch when inverted. Sorry for the bad inverted hovering, this was a year back when i just started.

[Jamin_00]

Looking good.

Interesting units both of these.

[ModelGuard.Com]

yes a firmware upgrade got rid of any tail shake ages ago