Sunday, October 26, 2014

SLH 6047 Scorpion review


The Why

Every time I buy a toy grade 'copter, I feel like I need to justify it. In this case, I was adding an RF module to my Devo 10 running deviationTx, and wanted something cheap to test it with, rather than risking the more expensive models I was planning on using this for.

The SLH 6047 used the new module, and wasn't just another toy quad. Or even a helicopter. So it was something new to try. Filling two purposes and having a good review from Flyin' Ryan1 made it an easy choice.

The What

What's unusual about the Scorpion is obvious when you look at it:

IMG_20141026_104136.jpg

It's got six engines on three booms, with a coax pair on each boom. The lower engine is inverted.

Some folks call this a tricopter, because it's got three booms. Others call it a hexacopter, because it's got six engines. I don't feel either is right, because it doesn't fly like a tricopter or a hexacopter, but will go with hexa because it could be called a hexarotor.

The Review

So, let's look at the thing.

First impressions.

To me, the pictures make this look a lot bigger than it really is. It's a small 'copter, being barely bigger than the Nano QX:

IMG_20141026_104220.jpg

Part of what makes it look large is that it also looks solid. This, unlike the size, is not an illusion. This thing is rock solid, and has a feeling and weight to match.
It's been through numerous crashes at speed and the only thing that's broken is a propeller. Unfortunately, it was the same orange one that was broken when it arrived2, so I've had to use the black spare, which is what's in the pictures.

In investigating replacement propellers, you can use standard multirotor propellers for the top ones. However, the bottom ones are pusher props, which are much harder to find in that size. Something to keep in mind if you plan on flying one a lot.

The flying

Coax multirotors tend to be stable but with poor efficiency. They have lots of lift for their size, which the scorpion needs because of its weight.

What that translates to is trouble overcoming its own inertia. It seems slow to respond to the sticks, and tends to keep going once you get it moving. The controller it comes with makes this worse, but I want to talk about that at length, so see further down.

This thing has been around for nearly two years. The technology in these things is changing fast enough that that's several generations old, and it shows. It doesn't even fly well compared to better toy quads of that era.

In summary, I can only recommend this if you want something other than yet another small quad.

The controller

It's been quite a while since I've looked at a toy RTF controller, and this one is much nicer than those. SLH gets credit for making it configurable enough to fly lots of different aircraft. All four channels can be reversed. You can also configure whether or not it beeps at you. Nice.

Toy controller problems

That said, it's still very much a toy RTF controller. While it has two rates, you can't set what they are. Nor can you alter the control curves in any other way. The fact that this aircraft is slow to respond is made worse because the controller seems to have a dead band near the center of the cyclic controls. Could be a quality issue with the one I got, or it could be designed that way so the toy-grade gimbals have a properly neutral center stick.

A hobby grade controller

Since the point of buying this was to test a new RF module in my hobby-grade controller, flying it with that was one of the first things I did.
This immediately brought a lot of new features to the table. A real throttle hold switch, to help reduce damage to the 'copter and bystanders during crashes. The dual rates are a switch, not a button, so it's possible to tell by feel if it's in low rate mode. Ditto for the flip functionality. Of course, all three have inverse video icons on the screen which are much easier to see than the dual rate symbols on the RTF controller. There is no indication that flips are enabled on the RTF controller, but it seems to time out quickly. And the RTF controller has no throttle hold, so that doesn't need an indicator.

More importantly, the dead band issue is gone. Getting rid of that makes the thing fly much better. Even better, I can apply some expo to the high rate curve, which makes flying it a lot saner. I feel that this justifies my avoiding 'copters that I can't fly with a hobby-grade controller.

The rant

It's not obvious if all you use is toy grade RTF controllers, but the controller is the important part of an RC aircraft system. It is the connection with your aircraft. So it having problems will also mean you will have problems with your aircraft . Similarly, if the controller is improved, say with better gimbals, or faster response, or whatever, then you'll have improved control of your aircraft, and an improved flying experience.

On the other side, getting the system set up properly is a critical part of an enjoyable flight. Large parts of the setup of a modern 'copter happen on the controller. Much of the functionality showing up on flight control boards can be done in the controller with a good enough controller. So again, a better controller means a better flight experience.

In summary, if you're just flying the toy-grade RTF controllers, you're cheating yourself out of a better rc experience.

  1. If you fly small 'copters and aren't familiar with his reviews, you should check him out. 
  2. Fortunately, it was fullfilled by Amazon. They couldn't send a replacement prop, but gave me $10 credit instead.