We’re pleased to add our first guest post to our blog. The below article is written by Ian Petrie taking us through his impressions of the new Out Of The Box Innovations VLXF230 quadcopter frame.
Drone racing is a fairly new sport, innovations come thick and fast as everyone tries to find out what will give them the edge over their competitors. We don’t have years of experience to call on in the way that they do in motorsport or fixed wing. It’s only in the last couple of years that battery technology has given us meaningful flight times and we’ve been able to crank up the power accordingly.
Frame designs have evolved too to improve survivability, efficiency and, most importantly, speed. No longer do we have thumping great double decked frames with six inch props, they have evolved into much lighter and smaller H or X frames. They have evolved in turn into stretched, low profile frames such as the Diatone Crusader GT2 or to the super thin Hyperlite Floss. Both of these attempt to improve agility and efficiency and toreduce the aerodynamic cross section of the quad.
The latest concept is to mount the arms vertically so that only the edge of the arm is presented to the airflow to improve thrust efficiency, yet retaining strength in the arms to survive the rigours of racing.
Hype aside, I believe that this will be the future trend of drone design for racing quads because it provides a great compromise. Two high quality examples have been released in the last year, namely the British made Fossilstuff Revo, a flat X frame using a novel rigging system to control vibration in the arms, and the beautiful, but expensive Karearea Talon from New Zealand.
Now there is a new contender in this category from Out of the Box Innovations in the USA in the shape of the VLXF230, a true X frame, and the VLSF230, its stretched X stablemate. Out of the Box’s Henri Brownell kindly sent me the true X version to review before its release date at the end of July.
The frame arrived very quickly in the post in a padded envelope, the frame was contained in a simple Ziploc type bag with a tag showing the frame model. I am a fan of minimalist packaging, anything fancier will only give you Facebook bragging rights and extra recycling. Don’t forget that you’re paying for that fancy box!
The bag contained some beautifully finished carbon fibre components; an upper and lower deck, arms, motor mounts and a bag of hardware. There are no build instructions included in the pack, but they can be downloaded by following the link on the label. The instructions are clear and simple with hints and tips on how to get the best from your build which is a welcome difference from the Chinglish guesswork that accompanies so many others.
The parts themselves are nicely finished with no burs or loose threads. The arms are a very solid 4mm thick and 10.5mm wide along most of the length. Remembering that they will standing on their end, this will hardly impede the thrust from the props at all.
The top and bottom plates are 2.5mm and 3mm thick respectively and hold the arms in place in a sandwich with the tabs on the arms locating in notches on the top and bottom plates. The assembly is held together using the metal standoffs as braces with Allen head M3 screws.
Personally, I’m not a fan of Allen head screws, nor using button or cap head screws on the body of a frame as they have scored my lipos in the past. They are universal, but my preference is for countersunk Philips screws instead.
Assembling the frame
I put the frame together initially without any electronics to get an impression of frame alone with its unusual configuration. The first step is to fix the standoffs to the lower plate and fit then to fit the electronics stack, which is a stage I’ll revisit in part 2. At this stage, it becomes apparent how much room you have to fit the equipment to the frame. It’s not wide open, but it’s certainly not as tight as some compact frames.
Next is the arm assembly. Other frames of this style use an aluminium bracket to provide a 90-degree interface to fit the motors too, but this one uses slotted carbon fibre plates with screws and captive nuts to hold the assembly together. They are, quite rightly, a tight fit and the motor mounts went together with a satisfying click. The captive nuts, however, were very fiddly to fit and I would recommend either needle nose pliers or strong tweezers to hold them in place before securing them in place with the M3 screws.
There was nothing in the instructions about how hard totighten down the motor mount. If the screws are bottomed out then the mount bows slightly and this will introduce unnecessary stress to the mounts. I made the decision to only tighten them enough to take the slack out of the fittings instead. The locknuts should be capable of holding them in place without any worries.
Once all four arms are assembled it is time to fit them to the lower plate. The manual has tips on how to adjust the fit of the arms whether they are slightly loose or tight. I found, as you’d probably expect since it’s brand new, that the arms were extremely tight and soit was necessary to file a small chamfer onto the edges of the arm tabs to get them to locate properly in the lower plate. I had to do the same to get them to fit in the top plate as well, but once I’d done that they fit very snugly. The dust can be hazardous so don’t forget to wet the sandpaper if you’re going to do this to stop you breathing in.
The top screws were then fitted to complete the assembly and the frame was finished minus electronics. I would recommend that you adjust the arm tabs to get the frame together rather than using the screws to jack the top and bottom plates together. This could damage your new frame and that will make you sad.
What struck me immediately about the completed frame was just how solid it was. The box structure of the frame is very rigid. There’s no movement in the arms vertically and very little horizontally. It feels quite substantial in your hand too, but at about 110g is in the same weight bracket as similar frames (Talon – 99g, Revo - 115g).
The relatively simple design means that it’s easy to take apart if you need to get at the internals for whatever reason, although the open design means that you can access th e ports and buttons quite easily. While assembling the frame it was interesting to notice some of the thought detail that has gone into the design, such as rounded corners on the cut-outs and tabs to stop stress risers.
There are also little details like notches on the plates to thread battery straps through, mount antennas, power connectors, etc. I also like the solution for mounting the motors with slotted carbon fibre rather than the machined aluminium brackets.
I discussed the frame with the guys from PropNuts once it was built. Two of them own Revo frames and so it was useful to get a comparison. Those who hadn’t see a frame with vertical arms were wary of the crash survivability if there was a front on impact, however at speed the quad will beinclined over 45 degrees in flight and so the arms will be stronger than on a frame with flat arms. They liked the use of the inboard tabs on the arms to provide the horizontal bracing and the location of the stack in the middle of the arms. The Revo has the stack on top of the upper deck and their feeling was that it was better protected in the middle.
To my mind there are a couple of things that could be improved, but they are only ‘nice to haves’ as the overall design of the frame is well thought out. First would be to round off or chamfer the edges of the arms, ifonly on the uppermost edge and on the arm tabs.
Second would be an aerodynamic pod of some kind and cone shaped feet for the motor mounts. They shouldbe an option for a frame with aspirations of being more aerodynamically efficient or at least be available as 3D print files.
So, to conclude, I’m really impressed! Let’s hope it flies as well as promised.
About the author
Ian is a native Glaswegian and literate engineer who hangs around with expert FPV pilots in the hope that some of their talent rubs off.
The equipment quoted in this article can be found by following the links below:
- VLXF230 (on review) – https://www.outoftheboxinnovations.com/store/p20/vlxf230
- Revo – https://www.fossilsstuff.com/store/revo/
- Talon – https://www.kareareadrone.com/shop
- Diatone GT2 – http://www.diatone.hk/goods.php?id=375
- Floss – http://pirofliprc.com/Hyperlite-FLOSS-5-inch-Racing-Frame_p_3921.html
- Luminier Skitzo flight controller
- Racerstar Tattoo 4x35A ESC
- Dragonfly 2206 motors
- Runcam Swift 2
- IRC Tramp HV VTX
- Frsky XSR receiver