REVIEW: RMRC Mudskipper 250
So this is a bit embarrassing… I’ve actually been too busy enjoying this thing to properly review it. I’ve made two videos so far, but haven’t sat down to write anything! My apologies, but at least there’s a good reason for it!
As far as 250-sized quads go, the Mudskipper 250 from ReadyMadeRC.com is something a little different. It comes in a frame kit, a PNP version, or an FPV PNP version. It’s a full carbon fiber frame with 5mm arms. 5mm! Good luck breaking those! If you do, RMRC covers them with a limited lifetime warranty! So what do you get with each version?
With the frame kit (priced at $69.99 at the time of writing) you receive, well, the frame and a simple power distribution board. The frame is solid and tough as nails, and has some neat ideas. The arms are set up in a way that the front and rear arms are two solid 5mm units, and the motors are spaced at a true symmetrical 250mm. You can spin up to 5″ props using the 2204/2208 motors of your choice.
The included PDB is rather basic, but allows for a 5v step down to be soldered in place as well as your ESCs, and offers a few accessory/FPV pads around the frame as well as an integrated XT60 connector in the rear. Note that everything is contained inside the frame – the FC is mounted upside down under the PDB and protected by another carbon fiber skid plate. This makes for a nice clean build, but clearance can be an issue so you need to be aware of the depth of your chosen FC. RMRC recommends a Naze32 or their excellent Seriously Dodo F3
One of the features I love about this frame is the adjustable camera mount. The FPV Camera, antenna, and an HD camera such as the RunCam2 are all mounted on a unified platform that can be adjusted for up to 25 degrees of tilt. This is great for those just getting into FPV since more tilt = more speed, so this frame can grow with you as your skills improve. My only complaints about the camera mount are the clamp that holds the FPV camera in place was either a little too large for my FatShark camera or the screw that tightens it stripped out almost immediately, and the vibration-isolation mount pops out completely in the lightest of crashes. This is when carrying a RunCam2, maybe it’s not an issue when using a Mobius due to weight differences? Both issues were simple to fix – I added to some bulk to the flight camera with shrink wrap around the lens assembly, and I used some tough nylon string to loosely tie the vibration plate to the camera mount. Not tight enough to compress the grommets, but tight enough that they can’t pop out in a crash.
The biggest thing I love about this frame is that everything is protected. The FC and ESCs are nestled securely in the frame, the camera and VTX have impact protection around the sides of the frame, and the battery sits down inside three walls of strong carbon fiber. In a crash you may be replacing a prop and bending an antenna back into place, but you wont’ be starting any fires from a prop killing your LiPo. RMRC also includes this black gel-like pad that is placed inside the frame below the battery. i don’t know what this stuff is, but I love it. It feels like a thicker version of those sticky hands you win at the fair, and it does a hell of a job keeping your battery in place with a single strap!
Things change a bit when you step up to the PNP versions, and this is what I personally own and have been flying as much as possible. You get the same frame, but the PDB is completely different and includes 5v and 12v regulators as well as the RMRC Seriously Dodo FC. The ESCs are directly soldered to the board with traces run out to the arms, and the FC is mounted in a very original way using a special ribbon cable. RMRC has run PPM and UART2 to the rear of the PDB by the XT60 with 5v and ground so you can connect a PPM or satellite receiver and fly out of the box, or re-solder one wire to connect via SBUS. They’ve also run UART2’s TX to a solder point on the rear for telemetry, which is great if you’re using an FRSKY D4r-II or similar receiver.
In the front you’ll find both 5v and 12v pads for your FPV gear, and a 12v accessory pad (also at each arm) for LEDs and whatnot. There’s plenty of room for your VTX and camera, and everything is nice and protected.
The PNP versions include the 2204 2300KV RMRC Blue Series motors by Tiger Motor, DYS 20A Opto ESC’s with BLHeli, and a few sets of HQ 5×4.5 Propellers. These motors run VERY smooth, and the props are tough. I swapped them out for some 5045 DAL Bluntnose V2 props, and it’s running great. Using a Turnigy Multistar 1400mah 4s 40-80C LiPo, I’m getting around 5min of fun flight time. Voltage drop isn’t much of an issue with this combo, though I’m sure stepping up to a higher C-rated LiPo would earn me another minute or so of flight time. Your mileage may vary of course. The frame supports up to an 1800mah 4s.
The PNP version is currently priced at $279.99, while the FPV PNP version is $389.99. The FPV version adds the Fatshark 700TVL V2 Camera, RMRC Cricket 200mw 5.8GHz Video Transmitter with Raceband, and the Video Aerial Systems 5.8 GHz Race Spec Airscrew Antenna (RHCP) for a complete package.
Complaints with the PNP versions? Well for one thing I couldn’t get my USB cable to connect to the FC. Apparently a few others have the issue as well, as the way the FC is mounted you need a thin cable to get around the frame. There is a hole to access it, but many USB cables simply don’t fit. If you have a Dremel it is an easy enough fix (see image to the right).
I love the RMRC Seriously Dodo FC, and the upgraded PDB makes the whole thing look super clean, but I can’t help but think RMRC missed some opportunities here. They made good use of UART2, but UART3 isn’t connected to anything and no traces exist on the board. Had they run it to the front it would be nothing to connect a MinimOSD and get all that tasty flight data, but that isn’t the case. No, if you want that you need to direct-solder a thin wire to the FC and run it up and out the front of the frame. Not impossible, but more than a beginner should be messing with. There’s no room nor trace for a buzzer either, so no integrated battery or lost model alarm. Not a big deal if you run telemetry and have a Taranis (and never land in tall grass), but it’s something I’m missing already. I sincerely hope that RMRC releases an updated PDB with additional traces and an integrated buzzer. I’d definitely pay for the upgrade.
RMRC sells spares for each part of the frame, and at decent prices too. You could even start with the frame kit and upgrade the PDB later, as the advanced PDB includes the RMRC Dodo FC mounted and ready to go. You need to solder the ESCs onto the board though, so beginners beware.
My few arguments aside, I love this thing. I ordered the PNP version because I didn’t want to mess with anything, I just wanted to fly. Out of the box it flew very well, though perhaps due to the decreased battery weight there were some oscillations. I migrated to Betaflight, running Luxfloat with stock PIDs and the result was a VERY good starting point. It flies great, and I can work on the tuning as my skills improve.
The Mudskipper has plenty of power and speed when you need it, even if it is a little on the heavier side for a 250 (I think my all-up wight is over 600 grams – I’ll double check and update later). It is tough as nails, having survived several hard crashes already and not even batting an eye. I’ve had cheaper frames fail from a hard landing, so believe people when they say “buy cheap, buy twice”. More often than not it’s more than twice.
If you’re a beginner looking for a solid learning platform with room to grow, get the PNP FPV version. It’s worth it. Over and over again, it’s worth it! If you’re an advanced flyer looking for a quality frame that doesn’t look like your standard 250, get the frame kit or the PNP. You will not be disappointed! For me, this is my new go-to quad.