My FPV Wraith

[RMNixon]

I've been tinkering on and off for the past several years with ground based FPV. There's a challenge that comes with trying to create a good, stable, usable video signal from an antenna a few inches off the ground. It's been a fun way to combine two of my favorite hobbies - ham radio and R/C.

I've built a Summit that's been through more incarnations than I can remember, and earlier this spring I used an Axial SCX10 chassis as the basis of a smaller, indoor rover. All my builds so far have been of the 'rover' variety - more of a platform to test technologies rather than something trying to re-create a full-scale driving experience. Lately I've been getting the itch to change that...

I've got a setup on my Summit rover that I'm happy with (for the moment) so I didn't want to go the Tonka Summit route (yet). I saw a few FPV SCX10 scalers, but everything looked really cramped. Then I saw this video:



That setup looked perfect to me! I really liked the look of the Wraith interior, and it's a capable enough vehicle to be driven just about anywhere. I spent a few more days watching FPV Wraith videos on YouTube. My mind was made up - I was going to build a Wraith FPV scaler. Having built a few ground based FPV rigs I've learned a few things that influenced me heavily in this build:

• Anything above a brisk walking speed when driving FPV feels like warp-speed, so this Wraith was never going to have to go fast or need a huge brushless power system.
• FPV gear and water don't mix! A failed FPV boat project taught me this. This Wraith is going to be sunny day, dry-weather rig only. No waterproofing necessary.
• Your perspective is a LOT more limited inside a vehicle than outside of it. That's why 1:1 off-roading involves a lot of spotters outside the trucks. Since I won't always be within eyesight and don't like the walk-of-shame to flip over a rolled truck, this Wraith won't be doing much serious rock crawling.
• Since I'm not going fast and I'm not doing any serious rock crawling and I'm not getting anything wet, I don't need a real fancy, quick, high torque, waterproof steering servo.
• Since I'm not going fast and I need a lot of nice low-end control I can use a cheap, sealed can brushed motor instead of an expensive brushless motor.
• Money saved on the motor and steering servo will go towards a Holmes BRXL ESC. There is no smoother brushed motor ESC on the market - PERIOD. Having nice smooth low-end control is critical in an FPV vehicle - you don't want the truck glitching or jerking from a dead stop and jerking the video around. No matter what anyone says, you CAN'T use this ESC in ANYTHING without a BEC! The internal BEC is weak and it will fry out over time. Plan on spending another few bucks and getting a Castle 10amp BEC to go along.
• Separate your antennas as much as possible! I was going to keep my R/C receiver antennas up front under the hood and keep the video transmitter antenna as far back as possible.
• The RC and the video equipment should ALWAYS run off separate batteries! Otherwise you're going to be constantly fighting noise and interference in the video link...

I started searching eBay for new or used Wraith rollers. Patience paid off when I came across a used roller with a few key upgrades. It's always a bit of a risk buying a used rig on eBay, but the pictures looked pretty good. The seller was quick to ship and when I got the rig it was in great condition!

It came with some nice hop ups:

• Axial aluminum c's
• Axial aluminum knuckles
• Axial aluminum rear axle lockout
• Aluminum steering lower link
• Aluminum upper links
• Level 3 droop kit
• Battery up front mod
• Axial aluminum shocks, red stripe springs
• 20t HPI motor
• 80t spur/18t pinion
• Fastback body
• Axial BFG Krawlers on Axial Trail Ready beadlocks

I stripped it down as soon as it came and went through the transmission and the axles. Everything was nice and tight and looked brand new. As much as I liked the look of the fastback body mod on the Wraith I wanted the stock roof and rollcage in place to protect the rear of the Wraith with the video transmitter and antenna in case of a roll-over. I found an eBay chop shop rollcage and ordered a clear lexan body kit from Tower Hobbies. I threw in a few cans of Tamiya Camel Yellow and Tamiya White, then Black to back it. I love Camel Yellow...

I reassembled everything, dropping the HPI 20 turn motor for an RC4WD 45 turn motor and replacing the 80/18 spur/pinion combo with an 87/10 combo. I hot glued the Holmes BRXL ESC and the Castle BEC to the frame piece the receiver box usually connects to (AX80081) and connected up the 45t motor. I installed a Turnigy TGY-5521MDHV and a 25t metal horn for steering duties. My eBay Wraith came with an aluminum lower steering link (the longer one) but was missing the upper one. Some 8/32" all thread and Traxxas rod ends provided a temporary fix until I can get something a little more pleasing to the eye. I also flipped the shock/link mounts on the axle to lower the COG a bit.

The electronics stuffed under the hood


I ditched the wheels and tires it came with and ordered up a set of Pro-Line TSL XL Swampers mounted onto an old set of Hot Racing aluminum beadlocks. The TSL XL tires are AWESOME! They're huge, sticky and they look just plain -mean-. The foams they come with GARBAGE. The ones I got weren't even round! I had to wet them down and heat them in the microwave to get them to expand back to a round-ish shape. After doing some reading on Wraith builds I ordered a set of Crawler Innovation Single Stage foams and a set of Double Deuce comp cut foams. I'm not sure if it's going to be smoother to have soft foams or harder ones which transfer all the load to the suspension. I've installed the single stage foams and they are light years better than the Proline stockers.

Pro-Line TSL XLs


My eBay Wraith came with aluminum Axial shocks. I thought for sure that would be an upgrade from the garbage plastic shocks I was used to. Nope - these ones leak just as bad. The oil that managed to stay in the bodies was 40wt and made the suspension way too slow for the smooth ride I needed, and the stock Axial red stripe springs were WAY too stiff and bounced all over the place. I replaced them with Traxxas Big Bores (TRA2662) filled with 20wt oil and I'm using a set of Losi white springs all around (LOSA5147). I had to cut the lower front bumper cross-member off with the new shocks on as it dropped the ride height even more. Compared to the Axial shocks I've got a lower ride height and more suspension travel - I'm very happy!

The cut crossmember and Turnigy steering servo


I used a Dinky R/C rear tub to house the video transmitter, video switch and LiPo to power the video equipment. The video transmitter is a Cricket 600mW 5.8GHz unit from Ready Made RC. I'm using a set of FatShark spiroNet circular polarized antennas on the video transmitter and receiver. I removed the driver's side seat and put a Ready Made RC Mobius pan/tilt kit in its place. I'm using a Mobius wide angle lens camera for my main camera and a Ready Made RC Pico Wide camera for my rear backup camera. A three-way video switch from GetFPV.com allows me to switch between cameras from the transmitter.

The Dinky R/C bed tub housing all the video electronics


The Mobius camera ended up really stuffed into the cab. The lens almost touched the steering wheel and its size limited how far it could pan & tilt. You can see in the picture below what I'm talking about.

The Mobius camera stuffed up against the steering wheel


The layout of electronics on the cage, you can see how little room the camera has to move around


I ordered an 8" extension cable for the camera lens off of Amazon. This allows you to take the lens out of the camera housing. I put the camera housing into the Dinky R/C tub and was able to shave down the pan/tilt mounting plate quite a bit before attaching just the camera lens to it. The difference was just what I wanted! The lens is now in the same place a driver's head would be and the view looks perfect from the video feed!

The lens outside of the housing sitting on the shaved down pan/tilt mount


The Mobius case now sits in the Dinky RC tub with the rest of the video electronics


I cut up an old piece of lexan to use a cover for the Dinky R/C bed. The hood is held on with high strength velcro. I run a 4s 1500mah battery under the hood to power the car and servos and a 1000mah 2s battery sits in the rear bed to run the video gear. I'm using a FrSky Taranis transmitter for control paired with a FrSky long range L9R receiver. The L9R comes with two external antenna which a glued to crossmembers under the hood. There's a set of aluminum lower links sitting on my bench waiting to go on. I'll post up some video as soon as I can get her out for a good test drive. For now, some picture will have to do!



Profile shot



Peek-a-Boo





Can't show off a build without flex shots, right?



My FrSky Taranis transmitter

[Osteo]

I gotta say, that is freakin awesome! the video you posted is cool, and with what you have done, I can only imagine! and a reverse camera to boot!!

[Inverted2112]

Looking great.
I've been debating if I want to go with head tracking on my Yeti. Won't be surprised to end up down that path as well.

[blarouche]

what kind of range can you get out of the transmitter. I have been thinking about doing this to my wraith, However I know nothing about FPV. It seems like you have to build your own system so it works well.

[RMNixon]

Osteo - Thanks man! I appreciate it!

Inverted - Thank you too! I'm not running any head tracking yet, the pan/tilt is running of the control sticks on the transmitter. I use a flatscreen monitor more than I use my googles, so I like having manual pan/tilt control.

[RMNixon]

blarouche - The video transmitter I'm using will go pretty far as long as you have a clear line of sight between the antennas. People using this system in the air have gone a mile or two out with no problem, but in the air there are no trees, rocks, buildings, etc to block the signal. The way it's configured now I can probably get 200' or so in any direction pretty reliably.

The lower the frequency you use for video the further out you can get, but the antennas get bigger and the video quality drops a bit. My FPV Summit uses 1.2GHz for video instead of 5.8GHz and I've taken it out over half a mile with no dropouts. I know it can go further, but I just haven't found a big enough place to try yet!

I built this Wraith to be an FPV trailing rig, if that makes any sense. I want to be able to trail with it, and when I find an interesting place I'll stop and put the goggles on and drive FPV for a bit. So I built it knowing I never was going to drive it very far out of sight. If my goal had been to drive across a few blocks in the suburbs way beyond my line of sight I would have done things a lot differently.

What kind of FPV driving appeals to you? Maybe I can point out some equipment that might work well for it...

[RMNixon]

It's a cold, but sunny and clear day here in Colorado. I took the FPV Wraith out for its first real test drive and was really impressed! It was nice to sit in my warm kitchen driving on such a chilly morning. The terrain is nothing too exiciting, I was just cruising around the yard but everything worked and looked great!

[Habanero]

Nice. Good strong signal or is that a recording only? I did this with my scx10 and fatshark rig but because it did not pan I was always paranoid when turning afraid a car/ person was coming from the side.

[blarouche]

I was thinking of an urban rig, like exploring around the neighbor hood, there are also old schools, and building complexes that would be fun to explore. It seems like the minute buildings get in the way, it is going to drastically reduce the distance. thanks for the info.

Originally Posted by RMNixon

blarouche - The video transmitter I'm using will go pretty far as long as you have a clear line of sight between the antennas. People using this system in the air have gone a mile or two out with no problem, but in the air there are no trees, rocks, buildings, etc to block the signal. The way it's configured now I can probably get 200' or so in any direction pretty reliably.

The lower the frequency you use for video the further out you can get, but the antennas get bigger and the video quality drops a bit. My FPV Summit uses 1.2GHz for video instead of 5.8GHz and I've taken it out over half a mile with no dropouts. I know it can go further, but I just haven't found a big enough place to try yet!

I built this Wraith to be an FPV trailing rig, if that makes any sense. I want to be able to trail with it, and when I find an interesting place I'll stop and put the goggles on and drive FPV for a bit. So I built it knowing I never was going to drive it very far out of sight. If my goal had been to drive across a few blocks in the suburbs way beyond my line of sight I would have done things a lot differently.

What kind of FPV driving appeals to you? Maybe I can point out some equipment that might work well for it...

[WT's Pauly]

Definitely cool. The video clarity and smoothness is great.

[Osteo]

Originally Posted by RMNixon

It's a cold, but sunny and clear day here in Colorado. I took the FPV Wraith out for its first real test drive and was really impressed! It was nice to sit in my warm kitchen driving on such a chilly morning. The terrain is nothing too exiciting, I was just cruising around the yard but everything worked and looked great!

That is just so cool!! and as you said, to think you are sitting inside just driving around! makes for a whole new crawling experience particularly if you are actually crawling.

I just picked up a 3S battery from a guy up here near my house, he has a small business selling parts for drones (apparently his engineering degree paper was on drones) he has some new Gimbal rigs he was trying to get me interested in what he was describing was also cool, I can now see the draw to them!

D

[MattTheGenus]

This stuff is really neat! Is there a forum or something I should be looking at for more information? I'd love to have one of my rigs set up to roam the hills.

[firstpasstommy]

Very cool! Good idea

[RMNixon]

Originally Posted by Habanero

Nice. Good strong signal or is that a recording only? I did this with my scx10 and fatshark rig but because it did not pan I was always paranoid when turning afraid a car/ person was coming from the side.

Habanero -

That's the recording from the camera, not what's coming over the air. Since I was still experimenting with the setup I was careful to turn back anytime the signal started to drop out, so it's also a pretty good indication of range with the receiver about a foot off the floor in the garage.

[RMNixon]

Originally Posted by blarouche

I was thinking of an urban rig, like exploring around the neighbor hood, there are also old schools, and building complexes that would be fun to explore. It seems like the minute buildings get in the way, it is going to drastically reduce the distance. thanks for the info.

blarouche -

Buildings in the way are always going to cut into the signal, but what you're talking about is certainly doable. The lower you go in transmit frequency, the better the signal will be able to penetrate objects. You might have real good luck with 900MHz or 1.2GHz for something like that. I used an SCX10 chassis with open diffs and a 1500mW 900MHz transmitter for an indoor rover, and it was able to get through brick walls, concrete, through floors, etc.

Your receiver antenna makes a huge difference too. You can get higher gain antennas, which narrow the antenna's field of view, but increase how far it can 'see' in that field. A high gain directional antenna would help you penetrate through a lot, but it would always have to be pointed in the direction of the vehicle.

[RMNixon]

Originally Posted by MattTheGenus

This stuff is really neat! Is there a forum or something I should be looking at for more information? I'd love to have one of my rigs set up to roam the hills.

MattTheGenus -

Most of what I've learned about all this I've learned by lurking on FPVLab.com. They've got forums over there, and one specifically dedicated to ground rigs called 'Ground Pounders". It's definitely worth taking a read through some of the builds to get an idea about antennas, frequencies, etc.

There's a dude on FPVLab and a lot of the other forums called IBCrazy (Alex Greve). He's also got a YouTube channel as well. He's an antenna GOD and has forgotten more about antennas than I'll ever hope to know. I try to soak up as much knowledge as I can from him.

Feel free to ping me too if you have questions or just want to chat about things. I'm no expert at this, but I've been having a lot of fun and learning a lot along the way! It definitely adds a new challenge to R/C!

[RMNixon]

Thanks for the kind words everyone!

I had a BLAST with my FPV Wraith this weekend! It was a sunny, warm beautiful Colorado weekend. On Saturday I fired up the old lawn mower (24" wide blade) and cut a path through some of the tall prarie grass growing on our property. The grass and brush has been growing all summer and stands about hip height now. It made for some very cool looking 'trails'.

Yesterday I put the receiver up on top of a retractable 20' antenna mast and drove over an area 3-4 acres in size. I had no fuzz, no dropouts, just clean video. I didn't try to go any further because that was plenty of space to roam around in! The mast takes about 10 minutes to setup alone and comes back down in half that time. I'm super happy with this setup!

I'm uploading a clip now of me exploring one of the 'trails'. I'll post back soon when it's ready...

[RMNixon]

Cruising my homemade trails...

[Unbalanced]

Outstanding! That's a helluva job you've done with this.

73

:-)

[Wavekatcher]

Originally Posted by MattTheGenus

This stuff is really neat! Is there a forum or something I should be looking at for more information? I'd love to have one of my rigs set up to roam the hills.

FPVLab.com

Good job with your Wraith RMNixon.