Low cost miniquad racing drone build video

Low cost miniquad racing drone build video

Review: LotusRC T580 Quadcopter

Review: LotusRC T580 Quadcopter

A TURNKEY HOVERING CAMERA PLATFORM

Dated: 26 Mar 2011
It seems that multi-rotor hovering craft are all the rage right now. A quick search on YouTube for "quadcopter" or "tricopter" will produce an amazing list of videos that show all manner of such machines.
Most of these craft are scratch-built and require at least a small understanding of electrical wiring. They also often require a bit of trial-and-error to sort out. The array of motor, control-board and configuration options is mind-boggling (and perhaps good material for future articles here at RCModelReviews).
However, there are some people who won't want to spend hours carefully constructing, testing, tweaking and improving their own home-built machines. They'd rather just buy a "ready to fly" system off the shelf.

That's where the LotusRC T580 quadcopter comes in.

What's in the box?

The machine itself comes in a large flat box that offers excellent protection against damage during shipping. My own unit came all the way from China with no additional boxing and, despite the best efforts of the Chinese soccer team (who obviously used it for goal practice), arrived in perfect condition.
Assembly is pretty straight-forward although it's worth noting that there are no instructions provided in the box -- you'll have to hunt these down online.
Bolt the landing gear on to the bottom of the craft, mount the propellers (taking care to get the right direction props on the right motors of course) and you're done.
Your RC receiver fits inside the black plastic dome and four servo leads from the T580's controller board deliver power as well as connecting the basic control signals (rudder for yaw, roll, pitch and throttle). Yes, you can fly this quad with even a basic 4-channel RC system.

My overall impression of the construction is that it's good quality.
Nice clean plastic moldings plus beautifully anodized aluminum parts combine to make the little quad look very well made. My only gripe might be that the props aren't well balanced and the arms are made from pultruded carbon rather than spirally-wound. The pultruded carbon tubes split easily and may be damaged in even a relatively modest crash.
What's more, despite being shipped with an impressive looking quality-control check-list, I found that one of the props and motor-bell assemblies parted company with the rest of the craft after just a few minutes' flying. Turns out the grub-screw was not properly tightened in the factory. And, when I checked the other motors, one had the grub screw missing completely. This is not an isolated case either - others have reported similar oversights. Check yours *before* you fly.
Once the thing is together, all you have to do is add your own 2200mAH 3S lipo battery (even a 20C pack will do but I'd opt for at least 25C to be safe). When your battery gets low, the T580 will start beeping its low-voltage warning but I'd advise using your transmitter's timer to land and replace the battery before it gets that low.

Flying the T580

This thing flies just like one of those coaxial helicopters.
Thanks to the onboard gyros and accelerometers, the T580 will simply hover all by itself. All you need do is correct for any drift and work the throttle to adjust the altitude (and you don't even have to do this sometimes -- as I'll explain later).

Given the price of the T580, I'd recommend that if you're totally unfamiliar with helicopters (even the coaxial type) then it might pay you to spend $30 and go buy one so as to develop your basic skills and orientation. Although the craft is very stable, those unfamiliar with "nose-in" hovering or who aren't used to using their rudder as a primary flight control may take a while to "get the hang" of flying it.
In calm conditions, the T580 is a piece of cake to fly. It simply hangs in the air and tiny corrections are all that's required to arrest drift or adjust its altitude. However, if the wind gets up the craft does seem to become rather wobbly -- sometimes over-correcting for wind (or pilot) induced disturbances. Strangely enough, adding weight makes things worse rather than better.
A barometric "altitude hold" system is also built into the Lotus and it tries to keep the craft at a constant height above the ground if you don't touch the throttle for more than 2 seconds. Unfortunately, mine didn't seem to work at all well and when the system kicked in, my T580 would often simply start climbing quite quickly or start falling rather quickly -- sometimes suddenly dropping several metres without warning, requiring rapid manual correction to avoid a hard landing. I have seen other T580s where the altitude hold was functioning properly and they seemed to stay within a meter or so of the original height.

Now for a few words of warning...
The T580 is a mild-mannered quad which is incredibly easy to fly -- until you push it too hard -- whereupon it becomes an unpredictable little craft that will tumble to the ground with little warning.
Many people have reported "unexpected flips" followed by a crash. So what's going on?
Well, after accumulating several hours of time on the T580 without a single flip I think I know the secret.
Firstly, the T580 is not designed to race around the sky at speed. If you try to fly it too fast or do steeply banked turns, it will flip.
Secondly, although the manufacturer claims that it will lift a payload of up to 580g, the more weight you add, the more likely it is that the T580 will end up on its back with a broken prop or motor shaft.
However, stooge around with relatively little payload, avoid harsh or sudden stick inputs and the T580 will work "as advertised".
Why is this?
The goal of the designers who created the T580 was to produce a simple, stable, very efficient quadcopter that anyone could fly around with ease. To that end, they have succeeded quite well.
Unfortunately, this has produced a number of trade-offs, and the size of the safe-flight envelope is one of them.
To get its incredible flight-duration (over 10 minutes on a 2200mAH battery pack), the T580 uses very large props turning relatively slowly and driven by low-KV motors. This means less of the battery's valuable energy is wasted in the form of drag or heat. The downside is that these huge propellers driven by their tiny motors can't respond very quickly to corrections from the flight-controller system.
When the T580 is disturbed from its normal "hovering" state, by a gust of wind or a significant control-stick input, the flight controller will speed up some props and slow down others -- so as to return the craft a level position. Unfortunately, if the correction required is fairly big, there is a severe "overshoot" and, instead of simply returning to "level", the craft will tilt back the opposite way. It then tries to correct for that movement and tilts back to where it was in the first instance. If the original angle of tilt was more than about 35 degrees, this oscillation will actually get larger rather than smaller and, within a few cycles, the craft will flip upside down and crash.
It seems that when the motors/props are sped up beyond a certain level, their very inertia is enough to keep tilting the craft past the level position and likewise, those motors which are slowed take too long to speed up again -- further exaggerating the overshoot.
Why don't other quads do this?
Well if you look at the fast, agile, aerobatic quads, you'll note that they have much smaller propellers that can be sped up or slowed down much more quickly.
However, with the T580, you must keep your throws low and avoid flying in turbulent or windy conditions that can precipitate one of these wobble-wobble-flip scenarios.
Another factor in some flip-over crashes seems to be temperature.
There have been reported instances of the T580 flipping without warning and these appear to be linked to heat buildup within the internal circuitry. I've flown the T580 in temperatures from 15 to 22 degrees C and not encountered this but it does get warm so I'm hoping that Lotus will address this possible issue in later versions.

If/when it crashes

Fortunately I haven't crashed the T580 yet but it's bound to happen. With this in mind, the craft comes with two spare motor-shafts, as these seem to be the most commonly damaged part in the event of an unexpected contact with tera-firma.
The shafts are hardened steel which tends to break rather than bend -- which is probably a good thing. Spare shafts are also available for a relatively small price.
Propellers are the next most-likely casualty in the case of a flip or other crash. These are a special propeller that has a threaded hub so you won't be able to just put a standard slow-fly prop on and expect it to work. However, the props aren't too pricey so, if you're buying a T580 it might pay to buy one or two extras -- just in case.
As I mentioned earlier, the arms onto which the motors are mounted, are pultruded carbon which can split very easily when stressed. If you're replacing the arms it would be good to see if you can find some spiral-wound carbon tube of the same size, so as to improve the durability.

Summary

As I've already said, I've flown the T580 for several hours now and had no problems other than the tendency to get a bit "rock and rolly" in wind.
I've kept the speed down, avoided sharp turns or harsh control-inputs, and it has flown very well.
As an aerial photography/video platform the T580 is hindered by its lack of *real* payload capability. Yes, you *can* lift 580g but every extra gram of weight you lift, increases the chances of an unexpected flip. I flew the T580 with a 2200mAH battery and a key-chain camera -- it flew great. When I flew it with a much heavier 4400mAH battery it was not so good and noticeably more wobbly, even though I was still well under the manufacturer's recommended maximum weight.

If you just want a cool quad to get into the multi-rotor aspect of the hobby or if you're confident you can fly within the limitations of the flight-envelope then the T580 is a really nice device.
If you're looking to do some casual aerial photography using lightweight and inexpensive cameras then the T580 is probably the single quickest way to get going. However, you will have to spend some time balancing the props to avoid the effects of vibration and limit your flying to relatively calm conditions.
If, on the other hand, you're planning to do serious aerial photography or video with heavy or expensive camera gear -- I'd be hesitant to recommend the T580 right now -- but...
LotusRC are one of the few Chinese manufacturers who are actively soliciting user-feedback and working hard to improve the product by fixing any deficiencies. To this end, I suspect that many of the product's current limitations will be addressed in future releases of the product. I'm hoping that I'll be able to test the next revision of the T580 and see how much they've expanded the safe flight envelope.
What is a disappointment is that the current system offers no user-upgradeable software capability and has no provision to adjust the gain/stability of the flight-controller -- perhaps this too will be added in later versions. I don't think it's too much to ask of a $350-$400 product that it has a USB connector on the side and user-upgradeable software.
Although there are obviously improvements to come with the T580, it can already be purchased from a growing number of online RC retailers such as HiModel.com.
Would I recommend the T580?
If you've got $350-$400 burning a hole in your pocket and you want something that is *really* different but don't intend ripping up the sky at speed or carrying heavy loads then yes -- it's a really, really cool bit of gear. Even with the current limitations, The T580 is a fun model that will turn heads, being quite different to the usual foamie fixed-wing or 450-sized helicopter.
If you want something more agile and capable of handling stronger winds however, then I suggest you keep looking -- or wait until Lotus make some changes.
Pro's:

• Super-easy to get flying
• Ideal for beginners to multi-rotor flying
• Incredible flight-times (10+ minutes on a 2200mAH)
• Very nicely engineered
• Great packaging
• Nifty altitude-hold (if you can get it to work)
• Some spare motor shafts are included
• Made by a company that listens to customers

Cons:

• Not suited to windy conditions
• Limited safe payload capacity
• Overcontrolling can produce a crash
• "Cheap" carbon arms split easily
• Still not 100% on the quality control
• No user-updateable software capability

• Product: LotusRC T580 quadcopter
• Supplied by: LotusRC/HiModel.com
• Price: around US$350-$400
• Overall rating: 4/5

Disclosure

Normally I buy all the products that are reviewed here but this quadcopter was offered for review by LotusRC and I accepted. LotusRC were made aware that the review would be objective and no favors would be granted. What you've just read is an honest review without any deviation from the facts.
Whenever a product that is reviewed has not been purchased with my own money, a disclosure like this will be made in the name of honesty and integrity.

Review: HobbyKing 900MHz FPV video system

Review: HobbyKing 900MHz FPV video system

CHEAP BUT LIMITED

Dated: 6 May 2011
One of the key components (some say "the" key component) of any FPV setup is the video system that transmits the video image from your model to the ground.
To date, I have been using the FoxTech 200mW 5.8GHz video transmitter and receiver to do most of my FPV testing but in this review, I'll be looking at the 200mW 900MHz system sold by HobbyKing for a surprisingly low price.

What's in the box?

The system comes packaged in a tidy cardboard box which contains the video transmitter, the receiver, a pre-configured wiring loom for the airborne side, a cheap AV lead, a cheap color camera, and two sleeved dipole antennas.

The first thing most people will notice, when comparing this system to a 2.4GHz or 5.8GHz one, is that the antennas are huge (and heavy). As the frequency goes down, antennas tend to get larger -- since hey have to deal with a longer wavelength of signal. In the case of the HK 900MHz system, the transmitter antenna really is too big and heavy for anything smaller than the Skywalker or HK EPP FPV models. These antennas are also far from well-matched to the transmitter, resulting in lower range and higher operating temperatures than would otherwise be obtained.

The lack of a bayonet connector and power-lead for the receiver seems to be an odd omission, especially given the thoroughness of the wiring on the transmitter end.

The quality of construction is satisfactory and the inclusion of the pre-wired loom for the airborne end is a big bonus for those who consider good soldering to be one of their weaknesses.
The transmitter end is configured to run of a 3S lipo without the need for an additional UBEC or regulator -- that's good. Even the camera will take the full 11.1V of such a setup.
On the receiver end you'll have to find yourself another 3S lipo and one of the barrel plugs which connect to the receiver. Be careful, there are quitea few different sized barrel plugs with different sized holes. Make sure you get one that is the right size or it will either not fit or will be intermittent in operation.

The Camera

If you're serious about FPV you'll ditch the cheap camera that comes with this system.

I tried the NTSC and the PAL versions, neither was really good enough for flying in anything other than perfect lighting.
The PAL version had a foggy haze that adversely affected contrast and the NTSC system, although not so badly affected, was unable to handle high levels of contrast between sky and ground without blooming and losing detail.
It's worth remembering that when you fly FPV, the camera is your eye so skimping here is not such a good idea. There are plenty of good FPV cameras available for under $100 so shop around if you want to improve the overall performance of this system.

The RF system

Given the excellent performance I was able to achieve from a 5.8GHz system, I expected that the 900MHz would be even better, at least in terms of range.
Unfortunately, that was not the case.
During test flights I found that there were noticeable signal dropouts at distances of just 1KM (1100 yards). It was possible to "fly through" these signal losses but then I discovered another unpleasant effect of this 900MHz system...


At distances beyond about 1.2Kms, my RC system began falling into failsafe. At first this was intermittent but, by the time I reached about 1.4Kms, the failsafe had fully kicked in. 
What was going on? In tests with the 5.8GHz system I'd repeatedly flown exactly the same RC system out to beyond 2.2Kms with no sign of any failsafe conditions. Why was my RC system now delivering only half that range?
Back at the workshop I threw the 900MHz system on the test-bench and found that it was creating enough noise on the 2.4GHz band to effectively mask the RC signal at longer distances. By comparison, the 5.8GHz system was clean.
The 900MHz receiver also seems to have a rather low sensitivity, a factor that compromises peformance quit a bit.
This all indicates that the system has definitely been "designed to a price" rather than with best performance in mind.
On the other hand -- it is cheap as beans so once again, you get what you pay for.
When time allows, I'll be adding a notch-filter to try and reduce the amount of spurious signal it outputs onto the 2.4GHz band and we'll see whether that restores some of the lost RC range.
In the meantime, despite having the same power as the 5.8GHz system, I'd have to say that this is a "close range" FPV system for those using 2.4GHz RC equipment. If you're running the old "long-wire" PCM/FM gear you may get more range because the amount of noise generated on frequencies below 100MHz seems to be much less.

A few words of warning

Although it's billed as a 900MHz system, the transmitter and receiver can actually be configured to work on much higher frequencies and on parts of the radio spectrum that are not legal for such use.
All but the bottom quarter of the 900MHz band, for example, are reserved for aviation use. Systems such as secondary radar, collision avoidance and other things are entitled to use these frequencies so if you're caught broadcasting an FPV signal on them you could end up in very big trouble.
US users can safely use channel 1 because that falls in their ISM band but in most other countries, this channel will interfere with GSM mobile phone services.
I will soon be looking at how these systems can be reprogrammed to use different frequencies within the 900MHz-1.1GHz band that may be legal in various locations. Stay tuned for that.

Summary

If you're in the USA and you're just looking to give FPV a try at the lowest possible cost then it's probably worth laying out the asking price for this system so you can decide whether FPV is for you -- without spending more than have to.
Don't expect too much though.
However, if you've already decided you're going to get into FPV then I'd look for something that doesn't have the drawbacks and limitations of this low-cost system.
Pro's:

• it's cheap
• pre-made wiring loom makes it easy to set up
• will operate from a 3S lipo

Cons:

• may reduce the range of your 2.4GHz RC system
• may affect the operation of your GPS (if fitted)
• camera is pretty crappy
• may not be legal in your part of the world
• stock transmitter antenna is too big/heavy
• poor performance overall
• only a single video-out connector on the receiver

• Product: Hobby King 900MHz 200mW FPV system
• Purchased from: LotusRC/HiModel.com
• Price: around US$50
• Overall rating: 2.5/5