OMPHOBBY M4
Building review and experience
I felt very privileged to be asked by Trevor Wallinger at Midland Helicopters if I would like to receive a pre release OMP M4 helicopter to build and review on behalf of themselfs and OMP. This was so that OMP had this M4 out there and in peoples hands and flying just before general release, so we can help new potential customers answer questions about the heli, and help new owners with any build questions etc.
I have already done a box opening video and shared a few teaser photos of this build here on my feed.
The build went together very well, but I had a couple of minor issues that I relayed back to OMP. Nothing major, just some simple things I picked up on. For example, the holes in the frame side where you pinch the boom support bolts up, my Scorpion driver would not go through the hole. I had an Allen driver that would, but suggested the holes should be drilled out slightly bigger. So nothing major, just things I picked up on that are easily rectified.
The standard of machining and anodising is extremely high. The Carbon side frames were perfectly cut, not a single splintered edge, but I still run a piece of Emery paper over the edges to smooth off any sharp corners etc.
The motor is a work of art!! It’s so nicely manufactured. Looking at the windings and cooling cutouts, SunnySky did a great job here.
The tail assembly is very simple, and the belt drive has very little resistance. Mine was slightly ‘sticky’ on the slider, so I ran a 5mm ream through the brass slider and span up the tail shaft in my cordless drill and used 1500 grit paper with light oil to polish the section of shaft that the pitch slider moves on. This gave me a super smooth assembly that would easily fall under its own weight when tipped on its side. One design feature here that deserves a mention, the use of shouldered bolts for the tail blades, so the blade hole does not wear on long threads. I wish all heli manufacturers would take note of this!!
The head assembly is again well made, of similar design to the majority of kits available today, and comes with turnbuckles as standard (again as all kits should these days) The mainshaft is supported by 2 radial bearings, either side of the oneway bearing in the direct drive motor. This motor is in turn bolted to the top main plate, and the main plate is sandwiched between the Cyclic servo rack and motor. So 3 bolts go down through the servo rack, through the main plate and thread into the motor. The servo rack carry’s the top one of the 3 main shaft bearings. It’s a decent size mainshaft at 8mm diameter and hollow to save weight.
I received the PNP kit that includes the servos and ESC. All the servos are aluminium body ones, and anyone who has seen the test flights from the models chief designer Jonas Wackershauser and other team pilots will have seen these are super capable servos! I set my Cyclic servos to 333Hz/1520uS and the tail servo to 500Hz/760uS
The ESC and Motor comes pre soldered with a XT style 3 pin plug and socket. The battery side of the ESC comes pre soldered with a panel mount XT60 plug that bolts to the lipo/ESC mounting rail. The lipo tray has a little frame that bolts to it, so your lipo XT60 plug is captured, so when sliding in the tray, it will connect the lipo to the ESC. This however, is where I departed from the stock setup. I spoke to Trevor about this, and he agreed with my decision on why I wanted to go with a different route with my M4. Because I use a V-Control system, I wanted very much to use the telemetry capabilities of this system. Simply put, I like to fly at varying head speeds, from cruising around to flat out speed runs, so flying off a timer is just no good for me. The OMP ESC has a full telemetry stream flowing from it, however after a number of requests, Mikado have as of yet, not allowed OMP to integrate their ESC with the V-Bar system. I think this is a real shame, because I know from a number of sources that this OMP ESC is super strong, and so is the internal BEC. Because of this, I opted to use a Scorpion 6-80A Tribunus ESC so I had full telemetry. Also, because all of my other Lipos and charge leads are all using SupraX connectors, I opted to use D4 plugs instead of XT60’s.
I opted to use the new V-Bar Evo flight controller, and as I worked with Doug Darby on the new Evo Aluminium cases, I’ve used one on this heli as a test bed for smaller heli use. One thing on the build I was looking at was that the servo wires pass above the motor can that’s spinning. Now this is not an issue, but please check you have your excess cables supported up and away from this. I opted to draw up and 3D print a small 1.5mm thick plate that bridges over the top of the motor and is stuck there with 2 small pieces of double sided tape. This just allows my cables to move about a little without fear of touching the edge of the motor can. Like I said, just use a cable tie or Velcro loop and it’s all good. I love the little M4 emblazoned carbon plate that covers up the wiring! Very neat idea.
As we had rain today, I could not get out to do the maiden, but hopefully that will be very soon. I’ve set mine up with 1800/2200/2600 HS, but this little monster will go upto a Tareq pleasing 3500HS!!!! I have set mine for +-17° pitch at 1800 and +-14° pitch for the other banks. I am using Optipower 6s 1800 50c lipos on this heli. The all up ready to fly weight of mine is 1427g or 3.235lbs.
I think that covers everything, if you have any questions or want and help with yours when they are available, please feel free to send me a pm.
I’d like to give a huge thanks to Trevor, Jonas, Mark Christy and Omphobby Chloe XU for your support and faith in me with helping on this project, and to Chris Clark at Optipower for my continued support.
