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Old Aug 08, 2013, 08:00 PM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
Joined Apr 2012
4,539 Posts
Mini-Review
Skyartec Butterfly Brushless Quad Review



Introduction

It has been a long time since I reviewed a multicopter. That review was for WLtoys V959. I realize my interest is more on collective pitch helicopters than multicopters. Toy-grade quads were fun but gradually, their lack of power made me feel that my CP helis deserve more flight time. Brushed CP helis got my attention for quite a while until I needed something more powerful to satisfy my addiction for power. When Skyartec first released an RTF brushless micro heli, I was very excited. I knew it is going to be different from the brushed V922. With the release of the brushless Butterfly, I believe that the brushless quad would rekindle my fire for mini multicopters.

I followed the developments of Butterfly as close as possible, posted a thread here to share updates on the product, and requested Banggood.com for one to review. It was my honor to be one of the first few to receive the Skyartec Butterfly RTF package for review.

I hope this review can provide basic knowledge of the product as well as answering the following questions:

1. Is this suitable for a beginner? Is it a good idea for someone with no experience in quads or helis to learn flying one with the Butterfly?
2. Is this a worthy upgrade for someone who has experience in flying brushed quad (e.g. V949, V959)?
3. Will an experienced multicopter pilot like the Butterfly?



Packaging

I was rather surprised that it came in a BIG package.



All my quads gathered curiously around the new guy.





Up close with the Butterfly

Just like the other toy-grade brushed quads, the Butterfly came mostly assembled - except the 4 tri-blade propellers.



While the props are not balanced, they are perfectly safe to be flown. For best results, especially for recording onboard videos, balancing of the props is strongly advised.



With only gray and black props for orientation, it is not a good idea to fly the quad too far. It is easy to fly too far because of its speed and the confidence it provides.



All that carbon fiber and brushless motors made the quad heavy. Flying this heavy, high-powered quad is going to be a refreshing experience for me. Exciting!

I actually tried to hover the quad without performing the required calibration. The quad flipped to the right the moment throttle was over 50%. So I removed the cover to perform calibration.



I took a while to find the calibration button and the gyro gain potentiometer. Look no further - they are beside each other, at 3 o’clock of the flight controller, standing perpendicularly to the board. Calibration was simple and the quad hovered nicely right after that.

The Butterfly gives me the impression that it is a big quad, but when compared with my V949 and V959, it isn’t much larger.



When a V949 is stacked on top of the Butterfly, it is apparent that the Butterfly is only slightly larger.



When I took it to the field, it was clear that its small size, props color combination, made orientating the quad a challenge. Strangely, my eyes tend to ignore the “X” shape and focus only on the ring, which confuses me badly. When the quad is far, it appears as a black ring in the sky, with no indication of its front or back. This is especially bad during high altitude piros. I almost lost my Butterfly that way.

I pasted bright, orange paper to the quad body to improve the visibility of the quad front.



That made a difference but the “ring effect” still messes up my yaws I tend to give it either too much or too little rudder during banked turns. I never had this problem with my X-shape quads.



Batteries

The package comes with a 2S 7.4V 1300mAh LiPo battery. It sticks to the battery bay with velcro and I don’t think that is enough to fasten the battery securely to the quad. As the battery may rock and affect stability, secure the battery with a velcro strap.



I happen to have 2S 850mAh LiPos for my Cessna. The only battery from the RTF package is not going to be enough so I would like to use my 850mAh for the Butterfly. However, it comes with EC2 connectors, and my lipos are using JST connectors.

I got some EC2s from my neighborhood hobby shop and made myself EC2-to-JST adapters.



One adapter for using the JST batteries on the quad, the other for charging the EC2 battery on my Accucell-6.



The adapter allowed me to use my 850mAh batteries on the Butterfly in addition to the single 1300mAh battery that came with the package.



The 850mAh batteries offer shorter flight times than the stock 1300mAh battery. While the 1300mAh battery is heavier than the 850mAh battery, it does not affect the flight characteristic of the quad. After flying the two types of batteries, I don’t recommend using batteries with capacities lower than 1300mAh.



Transmitter

Nasa 701 is an average transmitter that I am familiar with. I’m using one for my brushless WNCPX which I had swapped the throttle hold and idle-up switches around because I’m familar with having throttle hold on the right. I wanted to do the same to the Butterfly transmitter (as I’m not binding it to my WNCPX transmitter) but I realized that it would be pointless - there is no need to activate throttle hold when the Butterfly crashes. Here’s why...

To begin flying, apply full rudder right + 0% throttle to arm the quad. Once that is done, the props spin at a low rate. This reminds of car engine idling when it is not moving. Throttle hold does not stop the blades from spinning. To stop spinning, apply full rudder left + 0% throttle. I pushed my quad too hard, it crashed and ended up inverted. There was nothing I could do to stop the blades from scrapping the field until I flipped it over and disarmed the quad. Good thing the blades were scrapping grass instead of tarmac.

Prior to the first flight, check the transmitter settings. Mine came with slight differences from the manual. I changed two settings to make it less sensitive to my inputs:

- Added -20% expo for aileron and elevator; yaw rate is slow so no expo is needed.
- Lowered the throttle curve because it was too powerful for me. With the 0-25-50-75-100 curve, hovering is at mid-stick, which is weird for me. I changed it to 0-20-40-65-90 and the quad was less sensitive to throttle inputs.

Butterfly does not support flight mode changes (i.e. Normal vs Idle-Up). Therefore, we have no way to conveniently switch between gentle or sporty throttle curves.

While throttle hold is not useful for the quad, it is required to be activated before the transmitter is powered up. This requirement is annoying because this is irrelevant to the Butterfly and it does not serve a safety mechanism during power up. The arming of the motors is the safety mechanism.



Flight Experience

After arming the quad, the props spin at an idling rate. That is a clear reminder that flying the Butterfly is going to be different from my V939 or V949. As I applied throttle, I was greeted by the howling of the brushless motors. To me, the roar was just too loud to have been produced by such a small quad. My spider sense tells me that if the quad crashes at me, it is going to hurt much more, to me as well as the quad.



Like the other quads, as the Butterfly lifts off ground, it drifts slightly so corrections are required to achieve a vertical lift off. Beginners may find this a little scary.

Hovering the quad at a spot is easier than doing so with the V959. To make stationary hover easier, try applying negative expo and/or reducing D/R.

At outdoors, it quickly became clear that the quad is more stable, more resistant to winds, than my brushed quads. The amount of sudden ascend and descend caused by wind is significantly lesser. However, when wind hits the quad hard, it may send it moving just like my other quads.

Full rudder commands send the quad into a stable pirouette. It was able to piro around the spot but not on the spot. To me, it wasn’t perfect but you can be the judge when you watch the videos. I would prefer the Butterfly to have a higher piro rate; it’s a little slow for me.

Progressing from stationary hover to forward flight, I found the need to apply forward elevator constantly to prevent it from leveling automatically. This may be a useful feature for beginners or for aerial videographers, but personally I dislike that. I’m sure it could be fixed by reducing the gyro gain, but I’ll leave it at default for now.

With full elevator and full throttle, the Butterfly can accelerate to unbelievable speeds. As someone who does not have experience in hobby-grade multicopters, I was pretty amazed at the speed of my Butterfly during high-speed low passes. The sound of the four props whizzing past (together with doppler effect) is electrifying!

At the end of high speed low pass, the Butterfly was able to bank steeply for a sharp turn, before accelerating at top speed again. Laps after laps, as the brushless quad zoomed past me, I was kept on my toes while I pushed the boundaries of the quad. I allowed it to fly past nearer to me, as well as slowing down lesser for the sharp turn. I knew if I were to make a mistake or there had been a software error, both me and the quad would be hurt. That thought just heightened the excitement!

I was completely pleased with its performance that I swapped to a fresh battery, to try some flips. This is no auto-flippin’ V929 so I didn’t know what to expect. I sent it higher up for some fast circuits, before initiating pulling back hard on the elevator. The quad pitched up to about 90 degrees, lost all the speed, then went back to level. What an anticlimax! I tried different variations but my efforts were futile - the quad would not flip! Maybe next time I’ll revisit flips with a lower gain.

Landing the quad requires practice. The weight of the Butterfly together with the stiff landing gear, makes every successful soft landing a huge reward. Once the quad touches down, disarm the motors, and suddenly you realize how peaceful the field is (sorry for the exaggeration).



Aerial Videography

The quad appears to be designed for capturing aerial videos. Strong auto leveling makes it easier to keep the subject in the frame.

I don’t have a 808 or a Mobius camera; else I’d mount it below the battery bay. My F5000 is too tall to be mounted at the bottom, so I stuck it to the top of the quad. It was tough balancing the F5000 camera on top of a “hill” and ensure it is center and level.

The quad lifts the F5000 effortlessly. I couldn’t even tell if it was flying with a camera!.

I did my best to balance the blades and I was pleased with the results. There wasn’t any jello or jerkiness in the video. There were times that strong gusts of wind shook the quad a bit, which affected video quality.



Mods and Enhancements

Here are some suggested mods for your Butterfly:

- Apply bright colored tape or paper to improve visibility
- Attach rubber feets to soften landing
- Use velcro straps to securely fasten the battery
- Make EC2 adapters to allow the use of batteries with other connectors
- Get a keychain camera for capturing aerial videos
- Install LED lights for night flights



Questions & Answers

1. Is this suitable for a beginner? Is it a good idea for someone with no experience in quads or helis to learn flying one with the Butterfly?

I don’t think it is a clear “yes” or “no”, but I’m more inclined to say “no”. While it is highly stable, hovering and orientation practice can be managed easily, but its weight makes it more vulnerable to damage from crashes.


2. Is this a worthy upgrade for someone who has experience in flying brushed quad (e.g. V949, V959)?

This is a definite “yes”! Having experience will reduce the likelihood of crashes, and the power boost will surely be appreciated.


3. Will an experienced multicopter pilot like the Butterfly?

I can’t comment because I’m not an experienced multicopter pilot. The lack of detailed gyro configurations hinder the pilot from fine-tuning the quad to suit his/her flying style. Personally, I would love to be able to reduce the I-gain to reduce the annoy autoleveling effect of the quad. I suppose an experienced pilot could assemble a better quad, bind to the preferred transmitter, and all at a lower price.



Conclusion



To me, the strongest selling point of Butterfly is that the powerful brushless quad comes ready-to-fly. I see it as a hobby-grade quad that can be in the air minutes after extracting it from the box. If you’re someone who just wants to fly a brushless quad asap, without the need to assemble the parts, or to program the FC, ESC or transmitter; this quad might be the one for you.

Overall, the Butterfly is a great flyer. It is an excellent next-step for brushed micro quad pilots who are looking for more power, or those who are looking for a simple aerial videography (or even FPV) platform that their brushed quads are not up for the job. Beginners may not appreciate the powerful quad and may achieve better learning results with a lighter, cheaper brushed quad. Experts may find the Butterfly overpriced and lacking configurable options.



Pros

+ High performance quad
+ Requires no complicated assembly or configuration; Ready-To-Fly!
+ Highly stable platform for aerial videography or FPV
+ Good balance between stability and sportiness; well suited for intermediate-level flyers


Cons

- Not easy to distinguish front vs back; easy to lose orientation
- Uses EC2 connectors, adapters may be required if using 3rd party batteries
- No lights, unsuitable for night flight
- Low yaw rate / slow piros



Links

- Photo Gallery: http://www.flickr.com/photos/fyresg/...7634965691573/
- Skyartec Butterfly S: http://www.banggood.com/Skyartec-But...r-p-79716.html
- Skyartec Butterfly RTF: http://www.banggood.com/Skyartec-But...r-p-79716.html
- Skyartec Butterfly BNF: http://www.banggood.com/Skyartec-But...F-p-79947.html
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Last edited by FyreSG; Mar 21, 2014 at 02:31 AM. Reason: Added link to Butterfly S
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Old Aug 08, 2013, 08:02 PM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
Joined Apr 2012
4,539 Posts
Videos

Skyartec Butterfly Brushless Quad - Unboxing (6 min 19 sec)


Skyartec Butterfly Brushless Quad - First Outdoor Flight (8 min 3 sec)


Skyartec Butterfly Brushless Quad - Onboard Video #1 (6 min 52 sec)


Skyartec Butterfly Brushless Quad - Onboard Video #2 (Fast Circuits) (10 min 22 sec)
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Last edited by FyreSG; Aug 09, 2013 at 06:14 AM. Reason: Added 4th video - high speed passes
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Old Aug 08, 2013, 09:01 PM
Don't be popular, be right.
United States, FL, Port St Lucie
Joined Aug 2004
767 Posts
Nice honest and straightforward review. I like to see separate components under the hood. Means there is a room for upgrade and customization. Also should make the quad more easily repaired I'd think. I see real ESCs there.

How difficult do you think it would be to cut the ring sections out to make a standard X shape? Do you think it would affect the strength of the arms at all? Think changing the battery lead would be difficult for any reason? Are the graphics on the canopy just stickers that could be easily removed?
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Old Aug 09, 2013, 05:25 AM
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Thailand, จ.ประจวบคีรีขันธ์, Hua Hin
Joined Jul 2013
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Thanks for the review, I'll keep the eye on this thread, as my But is to arrive shortly.
What would you comment on the claimed 800 meters range, is that realistic?!
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Old Aug 09, 2013, 06:21 AM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
Joined Apr 2012
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Glad you like the review!

I don't think we should cut the ring away. The beauty of this quad is it is ready to fly without needing major modifications. While I don't think the removal of the ring affects rigidity, the hack job is going to be a great hassle. To improve orientation, perhaps there are better ways.

The graphics are not stickers. It appears to be spray painted onto the canopy. I honestly don't think it matters as the quad appears to be completely black from far.

It is tough to confirm the transmission range of 800 meters. Are you keen to use this for FPV?


I just uploaded an onboard video (4th video of post #2) showing high speed passes with the quad. You can see some imperfect banked turns because I had messed up my rudder inputs. The sudden pitch ups are caused by my weak 850mAh batteries, which did not have enough punch to pull off a sudden, steep banked turn. It wasn't easy forcing the video recording platform to be sporty. The quad simply refuses to go fast and furious! Anyone who is looking for a sporty quad, may be disappointed. However, lowering the gyro gain may help. Before I try that, I have to live with a non-sporty Butterfly.
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Old Aug 09, 2013, 08:26 AM
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Quote:
Originally Posted by FyreSG View Post
It is tough to confirm the transmission range of 800 meters. Are you keen to use this for FPV?
Indeed so
I've just placed an order for a 2m electric glider and also purchased an extra skyartec receiver to go with that. My plan was to operate both aircrafts using nasa701.
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Old Aug 09, 2013, 09:46 AM
Cranky old fart
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Germantown, WI.
Joined Oct 2007
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Very nice review, FyreSG. One question: It looks like G10 in the pictures, not CF. Can you confirm the material it's made from? Also, removing the ring would be a bad idea. It's inhibiting the arms from twisting.
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Last edited by Balr14; Aug 09, 2013 at 09:51 AM.
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Old Aug 09, 2013, 12:14 PM
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Nice review and nice quad!

Edit:

Can you confirm it works with Deviation (with hardware mod)?

Props to Skyartec guys for helping with the Deviation port. That's a nice attitude from a manufacturer!
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Old Aug 09, 2013, 02:08 PM
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United States, OR, Portland
Joined Oct 2012
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Great review! Seems this one is a good option for those of us wanting a powerful quad that is also forgiving. Now I really have to consider this bird more closely. After getting rid of my CPs, i said I wouldn't spend more than $100 on a flying machine. Here, the wind precludes FPs and small CPs choppers. But little quads like the X4 and V202 FQs do fine.
Do you think this quad has the guts to do okay in 10mph or more wind like the little ones? My V949/V212 hybrid with 959 motors is okay in these winds but not as good as the X4 etc.
Lastly, what method do you use for balancing the tri-props?
Thanks.
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Old Aug 09, 2013, 08:02 PM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
Joined Apr 2012
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Thanks for the compliments!

Balr14, I'm not sure what's G10. How do I tell if it is G10 or CF?

sbstnp, I don't have any Walkera products. So I don't know anything about Devos or Deviation.

hawaiichopper, the BF definitely fights wind better than any of my other 3 quads, including my V939 (may be similar to X4). I am unable to provide a quantitative assessment of its wind-fighting performance so I'll say it flies well in conditions that my V9x9 quads couldn't.

Balancing tri-props is tough! I may be doing it wrongly. I balance the prop (dangling perpendicular to the table) with a tiny screw driver (on the table edge), and put on tape on the lighter blade. It flies fine without balancing. The vibrations are very minimal that you need to examine very closely to see it, or you get jello when you record flight videos.
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Old Aug 09, 2013, 10:23 PM
Cranky old fart
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Germantown, WI.
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CF almost always has a pretty obvious woven pattern on flat surfaces and has a certain shine to it.. It's very brittle and has little resistance to twisting. G10 has a flat uniform color and may have small press or roller markings over the entire surface. G10 is a fiberglass product that's a good mix of strength, weight and cost and is more flexible than CF. I far prefer G10. It's much easier to work with. After copying your images and enlarging them, I would say it's definitely G10.
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Old Aug 10, 2013, 01:18 AM
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Quote:
Originally Posted by Balr14 View Post
CF almost always has a pretty obvious woven pattern on flat surfaces and has a certain shine to it.. It's very brittle and has little resistance to twisting. G10 has a flat uniform color and may have small press or roller markings over the entire surface. G10 is a fiberglass product that's a good mix of strength, weight and cost and is more flexible than CF. I far prefer G10. It's much easier to work with. After copying your images and enlarging them, I would say it's definitely G10.
Oh, that's really nice. As long as the flex is acceptable, it's a good choice. Wonder if the ring is needed to minimize flex. I'd really like to know how it behaves in 10-20 mph winds.
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Old Aug 10, 2013, 01:59 AM
Cranky old fart
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The ring would minimize twisting of the arms.
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Old Aug 11, 2013, 12:21 AM
KDS450QS(ZYX4),V977,CX-20
FyreSG's Avatar
United States, CA, Monterey
Joined Apr 2012
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Gyro Gain

Just did a test of adjusting the gyro gain potentiometer.

It can turn from 11 o'clock to (somewhere... can't remember! ) and it came out of the box at slightly more than 1 o'clock. I wanted a sporty quad. I thought lowering the gyro makes it autolevel less; I was wrong. It should not be set lower that the default setting.

At low gyro gains, the quad behaves badly instead of sporty as I had hoped initially. Low gain just makes the quad less sensitive to instability, ignores the need to stabilize itself, resulting in severe drifts and wobbles. Instead of being more fun, low gain makes it more annoying as the pilot tries to stabilize the quad manually. It's almost like the V911 without a flybar. At a gain of slightly more than 12 o'clock i.e. slightly less than the default value, the quad drifts badly like a drunkard, levels off either too little or too much like a see-saw, and commands feel very disconnected.

Therefore, setting it to the lowest value is likely to be suicide. I almost crashed the moment it lifted off to knee-height, and I was thankful to land the quad the safely.

Conclusion - the quad was never designed for high speed action.
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Last edited by FyreSG; Aug 11, 2013 at 10:34 AM. Reason: Corrected more weird expressions
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Old Aug 11, 2013, 05:21 PM
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Would think for the price there should be a better range of adjustments. Not so appealing now.
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