My MFE Fighter VTOL can provide multiple functions using the GoPro Hero 7 tilt-gimbal from Search & Rescue to Agricultural mapping. The large battery capability combined with the ability to hover or fly allows the Fighter VTOL to cover large areas. The 4+1 quadcopter design offers stabile control in wind using the latest Ardupilot firmware and features.
I’ve missed a lot of action in here while attending to other job duties!
I am currently buried in wiring harnesses but have mostly everything complete and hoping for a hover test flight tomorrow, weather permitting.
Cheers,
Christian
Hi Everyone - very interesting discussion…
I’m just wondering if someone could let me know what the diameter of the round carbon tube portions of the VTOL arms are on the Fighter?
Cheers
Jeff
Hi Jeff,
It’s 25mm diameter.
Welcome to the VTOL Plane forum! 
Thanks Greg,
I’m just about to go down this rabbit hole of VTOL 4+1, probably starting with a Ranger Ex or Skywalker X8 or FX-79 or Believer conversion and then perhaps a build of something like the fighter…but right now am absorbing all of the collective wisdom to be found on this and other forums here…It’s such a great community!
Cheers
Jeff
I was planning a Believer conversion myself and then I discovered @makeflyeasy sold a tilt motor version of the Believer called the Freeman. It would likely be easier to use the Freeman as a starting point rather than starting with a Believer. Here’s a link to the Freeman thread.
Thanks Duane, I’ll definitely check that out too.
I’m sure you’ll see me actively turn up on one of these threads when I start building - there will be questions no doubt…but for now it will be lurking and reading…
@JayDimarzio Tilt rotors can be trickier since you need to optimize the motor and prop combo to work for vertical (in combination with rear motors) and forward flight. You also have another possible point of failure with the tilt servos.
The 4+1 is a more reliable setup than a tilt rotor, imho.
Cheers,
Christian
3DXR is an agent in Europe, here is the link:
https://www.3dxr.co.uk/fixed-wing-c27/fixed-wing-kits-c105/fighter-t953
Hi Christian, Yes I like the idea of the 4+1 design and that’s what has brought me here to this thread in particular - but I am open to other systems - although maybe not a tail sitter! I’ve been flying RC fixed wing for twenty something years and have been using multi-rotors for various tasks for five…Getting a belly landing fixed wing with a big payload of batteries and gear back on the (sometimes not ideal) ground is tricky at the best of times. So although mulit-rotors’s definitely have their place and play an important role - VTOL fixed wing combo will be a nice and very useful addition to the toolkit.
I just did a CASA RePL license upgrade a few weeks ago using a Trinity F90+ which is a three motor tilter…nicely sorted out and flew very well…but also a closed system…I am definitely a builder, tinkerer and experimenter, so I would not be going down that pathway…hence the reason I have arrived here…and there’s a whole lot of experience here to draw on…and hopefully be able to add something worthwhile along the way
Cheers
Jeff
Hi Greg,
I would be very interested in setting up a MFE fighter as a 6S configuration similar to your build which by the way looks very impressive. I have the same Tarot 5008 motors, same props and hobbywing Xrotor 40 amp speedy’s etc.
I intend to do mapping work with this machine and so would run this with a Pixhawk cube orange - Here 3 GPS and Here + RTK setup - using Horus X10S express radio with RF Designs TX MOD in the module bay, so I can transmit/receive mission planner data and also RC Tx control inputs through the Horus as well, through the 16 PPM channels on groundside radio - (RFD TX MOD) and the airside RFD900x 900Mhz radio modem instead of any FrSky receiver etc. I would also run an Emlid RTK setup onboard as a secondary GPS system (only to gather data, not navigation dependant) as well to record the camera (A6000) hotshoe timings - provided I don’t have conflicts with the two onboard 900Mhz systems (emlid has a 900Mhz LORA radio) and if I do - I can just ditch the LORA radio and still record to the Emlid GPS for PPK…that’s the theoretical plan…and this bird seems to be an ideal platform…After I mess about with some other VTOL conversions first…to gain some experience first.
So my question for you Greg is, now that you have gone through the entire process with the fighter and have some very nice flight tests under your belt with your 6S system, would you mind sharing your thoughts on your system overall and providing a list of what you ended up using as far as equipment/components goes and where you ended up with MTOW etc? It would be most helpful ad appreciated - no rush - just when you have time…
I am interested in keeping it at around 7Kg if possible…doable?
Cheers
Jeff
Hi Jeff,
It’s all been posted above already. I tend to broadcast everything I do so that others can decide to use it or go another path. I would use the search feature and select the “Search this topic” box. By searching for “GregCovey” you’ll find my posts in this thread or on the whole VTOL Plane forum.
I’m quite happy with 6s the power system. It is low-cost, light, and no modifications are needed in the assembly. I purchased spare motors, ESCs, and props but have not used them yet. Granted, I fly for hobby fun and not commercial missions. I used the PIDs from the MFE example param files (also posted) and they worked great for both hovering and forward flight. I use a single 6s 21AH pack that used to fly my DJI S900 that I sold to the University of North Carolina. I have 3 packs which can produce more flight time than I have patience for.
On my Horus X10S, I use OpenTx with the Yaapu telemetry addition that pumps MavLink into the SPort for FrSky telemetry. I also use a parallel 3DR telemetry to my tablet for QGC or laptop using MP. The 5.8GHz video broadcasts to many ground links like my FieldView 777SB monitor, Black Pearl, Eachine goggles, and sometimes custom Tower app using the Eachine ROTG02 UVC receiver.
My health is poor so being able to put the finished Fighter back in the box and cart it to the flying area or pits is a big plus for me. I also like the tool-free quick assembly at the field. I added instructions and images to the inside flaps of my box just in case I get a “senior moment” at the field. 
The biggest issues I had with assembly of the Fighter (and Freeman) was gluing the halves together (without two people) and creating the wing wiring harnesses. If the kit had these assemblies already finished, it would relieve a good part of the assembly process. So the design is awesome, it just needs to have less assembly work.
Cheers!
Jeff,
Excellent! I am looking forward to drawing on your experience with fixed wings, welcome to the forum. I am also not a fan of tail sitters. The 4+1 is ideal for the conditions and data I collect (upgrading from a wing with a pusher motor).
Cheers,
Christian
Hi Greg,
OK I will scour the history for details…there is a lot of very good material here from you and others. I mainly wanted to get get your overall impressions of the machine and your setup and you’ve definitely given me that so thank you for that. I guess my ideas if I go ahead with this build is to setup as simply and as cheaply as possible to carry my gear around and do the work…and to get a feel for whether I upgrade this to a 50 volt power system or move on to something else into the future… Anyway thanks again for all the info…
Cheers
Jeff
Hi Christian,
Thanks. Yes I’ve been skimming over hundreds of posts here and your material comes up all over the place. Interesting to see a few of you guys getting these aircraft built and into service for work and fun. A lot of my years of fixed wing were old school hand launch and discuss launch gliders back when radios had rather long antennas…but only recently (over the last few years) after a break for quite some time - I got back into it and found the world had dramatically changed for the better and the development that has occurred in the open source software and hardware world is simply amazing and very empowering, if not totally consuming at times…
Yes the 4+1 definitely has the most appeal for me too.
What data do you collect with your dragging sensor?
Cheers
Jeff
Nice. There is a lot of useful information to be found in the forums including the “lessons learned” posts.
Technology has changed quite a bit since the early days. My father use to build and fly RC model planes and gliders when I was young.
I chose to do a 12s power system as a “heavy lift” endurance build for a magnetometer sensor. Currently I am preparing for some multispectral sensor missions on this same build. Magnetometer surveys will be setup after I finish the multispec surveys.
I’ve had good results with EMLID modules as I have been using them for land-based geophysical surveys for the past 3-4 years. I incorporated the original, single band RTK module into my last multispectral build to collect PPK data. My suggestion is to stick with PPK and event logging triggered by hot shoe (or pmw) on the EMLID module as RTK really isn’t that useful when you will post-process the data afterwards anyhow. RTK can be quite finicky in the field and slow your surveying down so unless you need to actively fly to an exact coordinate, I’d stick with PPK (it’s cheaper in $$$ and time). We upgraded to the EMLID M2 multiband modules this year and they seem to be working well thus far on land. I’ll share photos soon of my setup once I finish the battery tray that holds the VTOL dedicated LiPo’s in the cargo area.
Cheers,
Christian
Hi Christian,
Yes a crazy amount of useful information - across many threads, with some that appear to be running in their own parallel universe (different airframes and types etc) and some cross pollination going on between them too, thanks to some very active members…so there’s a lot to read, to sort out where to best place your efforts and zero in on the things that are relevant to your own situation and interests and also where you may be able to provide some relevant input of value to other users as well etc…way better that though, than no activity at all…it is a strong and vibrant community!
Yes I can see why you would want a 12S power system…I’m sure you will need it with your configuration. Do you use the Emlid gear for CGP’s and ground based feature survey data to tie in to your multispectral survey data? Do you ever collect GNSS event data in the air with an M+ or M2 for RTK or always just PPK on board your aircraft?
Thanks for your advice on the RTK side of things. It helps to put this into perspective for a practical and efficient workflow, and not to overdo or replicate the basic process.
I will just be using the single band Emlid RS+ and M+ with the hotshoe trigger to start with. I’ll mostly be out in the open (not really much in the way of mulit-path problems). I agree, RTK is great when it is all working and mildly inconvenient when it’s having interruptions on ground based surveying - and much worse if it drops in and out whilst in the air…So I guess what you’re saying is, I’d still have to back fill the RTK data holes by PPK processing anyway, so why bother with RTK in the first place? Makes perfect sense and makes for a less complicated and less power hungry setup…
I used a couple of different CORS based RTK systems from Topcon, collecting infrastructure data for my GIS at the University I used to work for, over the last ten years and the RTK was sometimes a bit flaky - there’s lots of components that all need to be working together in order to deliver the corrections.
I’ll probably still use the Here 3 and Here + for the nav side of things, so that system should take care of those duties and the camera event data can be recorded separately on the Emlid system - and to the Pixhawk 2 logs maybe?..or do you think that there is no point to even use the Here3/+ RTK system for the nav? I am just thinking here about accurate flight path repeatability for things like mapping grids, inspection routes, transects and the like…
I really look forward to seeing your setup photos…especially with the separated power systems…this is also an idea I have had stuck in my mind for some time…a lot of advice I have had from others is to just go with ONE big Lipo to run everything…I am still determined to separate my systems but open to suggestion…
I have in mind for my setup, a 6S - 6000 mAh Lipo (2x3000 in parallel) setup for the VTOL system and a 4S - 14000 mAh LiIon (2x7000 in parallel) for the thrust system (where less current draw is required and the Lithium Ion providing more mAh capacity for a given weight) - just thinking about multiple redundancy here by having two batteries in each circuit and separating each of the power systems, and having the lift Lipo’s nice and fresh(ish) provided I get a clean/quick take-off and transition - ready to deal with whatever the conditions may be when landing later in the flight…Also possibly have a third dedicated small Lipo/LiIon to run other things from an 8 amp UBEC and provide some more redundancy… I’ve sketched up a rough draft diagram a few weeks ago of what I was thinking and should dig it out and share it for others’ comments…
I really like the idea of the Fighter (and its ability to add more gear or batteries later if I start light) although the more I move towards starting this project, the more the MFE Striver starts to make more sense for my application and component setup…anyone here building or thinking about building this airframe?
As I said in an earlier post - I may even put this all together first on a Ranger Ex as a test bed unit so I can learn and make my mistakes on this. Any thoughts on this?
Cheers
Jeff
I use ground control points and log events from the shutter output signal as well as PPK. My GCP’s are not as useful in the wetlands I fly since dry land access is extremely limited. In practice, not all of the events get logged to the Reach RTK for unknown reasons (perhaps the output pulse has issues). Because of that, I collect PPK data so that I then can match up the GPS times from the images to the sUAS path. We use a Micasense Rededge/Altum camera with their light sensor which geotags images using its own GPS.
Agree 100%. For most of our uses the single band has been excellent for terrestrial (land) surveys though we occupy a site for for approx. 10 minutes of static GPS logging while collecting other data. The general terrain of my study areas are pretty open (aside from canyons) and not a whole lot of tall vegetation to create problems (Utah is mostly desert).
If you already have a Here3 then I’d use it on board. I have a Here2 for nav because of cost and availability at the time I ordered parts. My previous build had a generic M8N which was also fine. Either version of the Here will work fine for logs and nav. You’ll have PPK from the EMLID which will be easier to work with than location data from a flight log. You could do a flight path comparison of the two, but ultimately it will come down to the processing software you use to create the final orthomosaics. If you have good coverage (overlap) then the precision/accuracy of the center of each image is less of an issue especially when you have GCP’s and good software.
I’d only use GCP’s with PPK to check the final orthomosaic or as a safety net if one of the two methods fails. If terrain/access is prohibitive regarding GCP’s, then PPK or RTK are really your only options.
Happy to take a look at your draft schematic, I could update and share mine now that wiring is complete. I like the idea of having power redundancy and not just a spare BEC because if the battery fails then it won’t matter. I am still on the fence in deciding to use the VTOL LiPo battery as a backup to the primary Li-Ion battery or keep it separate and just monitor the voltage/current. I need to look more closely at the battery failsafe parameters and wiring connections before I try it.
If you find any good info on common signal, let me know. I’ve seen chatter but not explicit details. This is the most detailed post regarding double battery (power) I have found thus far: "DoubleBat" Power Supply For Quadplanes - #29 by Rolf
If you have a proven airframe then it’s easy to add components to it to test (most of the time). Building a new airframe you still have to get to the point of airworthiness so maybe it comes down to cost of repairs if a test flight has an “unexpected landing” and needs fixing?
Cheers,
Christian