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FPV Dogfight with Head-tracker in a Spitfire... a Journey to get there

#1
Though there are many FPV flyers, I am surprised that very few of them have taken an interest in flying from the cockpit of a scale plane with head-tracking to imitate the experience of flying a real airplane (sans G forces). Flying from onboard FPV perspective makes some challenges that were previously impossible with LOS flying possible, such as proximity around obstacles, long range, close formation and dogfight! But it takes some effort to become proficient at this. And reaching the goal is so much fun and definitely worth it!

Begin with the end in mind: Scale FPV Dogfight!

Short clip of dog fight:

Full flight

I hope by showing the steps I took to get here, more people would by inspired to give scale FPV with head-tracking a try, and join in the fun of dogfighting, formation, chase etc.
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I have always wanted to try this, but the low resolution of realtime analog FPV video feed have kept me from action. However, after seeing the HD video feeds from aerial photography drone like DJI Mavic, I thought how wonderful it would be if DJI would release an independent HD FPV system from their drones. And they finally did last year (2018).

So I jumped at the chance and bought their DJI Goggles Racing Edition Combo, complete with VTX, camera and headtracking capability. Immediately Installed it in a scale plane that I was already flying comfortably with LOS. And the visuals were simply breath taking....



To test the system out first, I flew line of sight while friends took turns wearing the goggle to joyride. And I review the recorded footage afterwards to familiarize myself with the sight picture from the cockpit...

 
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#2
The FPV system worked flawlessly. So I asked friends to test out my training regime. I let them fly the plane under FPV first using a buddy box while I act as safety pilot flying LOS using the master transmitter. I took off first under LOS and gave controls to my friends once safe in the air for them to try out FPV flying from the cockpit. Denny is a airline pilot, but he was not particularly fast at adapting to flying FPV. I guess since RC planes react so much faster than what he is used to seeing from Boeing 737 cockpit. Another friend Gene, a known smooth stick flying RC LOS, seemed a natural from the moment he had control. Flying the plane under FPV as if he had always flown the plane that way!



The same training flight from the ground perspective



I thought this training system is fool proof. Gene can now act as safety pilot flying LOS while I take the controls flying FPV. If anything goes wrong while I was under FPV, Gene with the master transmitter simply takes over control. So simple! And I am so excited to finally try FPV fight!
 
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#3
Everything was ready! My turn. I sat down with all systems go and a few seconds into the takeoff run my FPV feed started pixilating. But I was committed on the takeoff since I did not want the VTX to overheat as it needed air flow to cool down. Then disaster struck, I lost power and yelled at my friend to takeover control. But the plane did not respond. CRASH! My first FPV flight experience was over in mere seconds.



I was so gutted, I took the wreckage home and could not bear to look at the thing for months.....
 
#4
Probable cause of the crash was due to RC signal interference from VTX signal. I used DJI default VTX setting which auto selected channels in both 2.4 GHz and 5.8 GHz bands; I was using a Spektrum DX7 2.4 GHz for RC, big mistake. I should have manually selected a clear channel for video transmission in 5.8. And indeed ever since implementing this practice, I have not had any breakup in visual signal, not even a line of static or noise, ever. Such is the stunning visual quality of digital HD FPV system.

Other contributing factor was overheating of the VTX. The VTX was installed under an enclosed canopy. While there were vent cutouts, the plane did not takeoff within a few minutes of powering up the VTX. So residue heat from previous flights and green house effect from the sun both contributed to heat built up of the VTX.
 
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#5
Fast forward a few month, I had lost confidence on the reliability of that FPV system. So I picked a previously crashed/repaired pattern plane to transplant the FPV system. It would not sting as much if I crash this beater plane, I thought. That turned out to be a great choice as I was less apprehensive on my FPV maiden. It was big with long moment arms so flights were smooth and looked very realistic under FPV.

I thought I would train like real pilots - focusing on safe takeoff, landing and flying the traffic pattern. I no longer used a buddy box since that didn’t help the last time. Just asked my spotter to call out approximate height during my approach and landing. And off I went...


It turned out very well. After 3-4 flights, I was used to flying FPV and had much better grasp of height above ground without the spotter’s help.
 
#6
As I gained more familiarity and confidence flying FPV, I was eager to try chasing my friend’s plane (flown with LOS) to see if using the pan & tilt head-tracker was indeed much easier to keep a fast moving bogey in view.

The result was a resounding yes! In my first ever chase/dog fight practice using head-tracking FPV, I kept my friends plane in view for > 99% of the time, and did so with less than a handful of FPV flights experience.

 
#7
I always loved flying chase/formation with RC friends. But because of limitations from ground view , it was nearly impossible to maintain close formation with safe separation in LOS flights.

With HT FPV, however, I can maintain clear view of the lead plane at all times. And by deliberately maintaining at a stable position 45° behind and below the lead plane, and staying on the outside of turns, I can maintain safe separation even if minor mistakes are made.

So on my next FPV training day, I saw a guy making 20+ consecutive greaser landings (touch & goes flying LOS). I was impressed by his smooth style of flying and proficiency. So I asked if he wouldn't mind flying smoothly for me to practice close formation. He agreed and I went over how I would remain safely clear of his plane, and he would tell me his every move in advance. Then we gave it try. In two flights, we were able to maintain position thru turns and stay consistently close, within 15’ from each other. We even attempted a loop in formation and was able to stay close in the first half.


My new friend turned out to be an airline captain flyin Boeing 777 and 747. I can’t believe how lucky I was that day as I believe a smooth lead pilot is the key to success of flying formations.
 
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FoamyDM

Building Fool-Flying Noob
#8
This thread and videos are spectacular. I have a lot of questions about the setup.
I have a Skyzone V02+ and have yet to setup the FPV with headtracker. I have an AT10 transmitter, and a Jumper TS8G.
I want this to work and should have some time over the next month.

How are you setting up the channels to to input from the Headtracker?
More details. Which PanTilt kit did you use? What camera are you using?

Where can I find more detailed information about the Sight. I would like to use the idea for more of a HUD.
While I won't be doing this RIGHT NOW, it is my next level and has a spot in at least 2 of my builds
 
#9
This thread and videos are spectacular. I have a lot of questions about the setup.
I have a Skyzone V02+ and have yet to setup the FPV with headtracker. I have an AT10 transmitter, and a Jumper TS8G.
I want this to work and should have some time over the next month.

How are you setting up the channels to to input from the Headtracker?
More details. Which PanTilt kit did you use? What camera are you using?

Where can I find more detailed information about the Sight. I would like to use the idea for more of a HUD.
While I won't be doing this RIGHT NOW, it is my next level and has a spot in at least 2 of my builds
Thanks FDM! I was not well versed in all the different FPV systems so I picked one that was as close to turn-key all-in-one solution as possible. Head tracker is built-in with my goggles. Camera and Air Unit (VTX) is also included (DJI Goggles RE Combo). No interface needed with my RC transmitter. HT signal is transmitted directly to Air Unit to activate the pan & tilt servos (needs a PPM to PWM converter between Air Unit and servos). How my HT works:


The Pan & Tilt mount I used is this one: https://hobbyking.com/en_us/fpv-fiberglass-pan-tilt-camera-mount-l-size.html

Working scale reflector gun sight made by German master scale builder, Tim Noack. More info about the sight here:


 
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#10
So after gaining some proficiency flying FPV and proving with head tracking, it is a system that would enable me to realize my dreams of flying formation and chase/dog fight realistically. It’s time bring the level of my aerobatic ability up to my line of sight flying levels.

Since I love precision/pattern aerobatic flying in LOS flying. I started practicing the same moves under FPV. After a few flights, I find that I became more precise flying FPV than LOS since I can see the plane’s attitude in much better detail.

I also gained more confidence doing low level flights under a FPV. There is an arch formed by two trees in the middle of our flying field. To prove my low level flying chops, I wanted to fly through the arch and pay homage to Ray Hana for his Spitfire under Bridge feat.

Here’s a flight of aerobatic training and tree arch pass...
 

FoamyDM

Building Fool-Flying Noob
#12
Nice Vid! again.:)
Regarding the sight - I will have to "talk" with the German. I have ideas and this is in the wheelhouse of the end goal. Thank you for presenting it here. It's very next level experimentation stuff with RC
Do i understand it right? the goggles send the signal directly to the plane via separate receiver which is then converted to ppm for the servo?
 
#13
FDM,

Thanks! Correct on the separate receiver getting headtracking signal from goggles directly. It is integrated with VTX - called Ocusync Air Unit. It outputs from a serial port in PPM, but servos require PWM to move. Therefor a PPM to PWM converter is needed in between. Or you can use a flight controller instead.
 
#14
After fully exploring the capabilities of the pattern plane, and starting to settle into a routine every time I took it for a flight. I thought I should move onto the next challenge - flying from the cockpit of a scale warbird. But which one? I decided on a very scale Spitfire - Avios Spitfire Mk Vb by HK. It was developed by Spitfire enthusiast Stuart Warne with help of RC scale expert Tom Hunt; so it has the most scale outline of any model Spitfire in production. It also has many FPV centric features such as removable front wind screen for clear FPV view, sliding canopy and side door for access to cockpit to ease installation for FPV equipment. And even flap indicators on wings to show that flaps are lowered (split flaps so they are hidden from view. Since I am not a major modder, these attributes made it an easy choice for me.

So just like the other FPV planes I flew. I want to get familiar with the flying characteristics of the new Spitfire by flying extensively in LOS first.

I like maidens, it's that rare opportunity to experience butterfly in the stomach feeling not knowing what to expect that only happens flying a unfamiliar, emotionally attached plane. And on this maiden, during butterfly migration, there were even plenty of butterfly in the air to heighten that sensation!


It was apparent that this is a great flyer in the air, but ground handling during takeoff, landing, roll out all presented challenges due to the very narrow stance of the main landing gears. And with the long nose pointing skyward, I knew even taxi presents challenges in FPV view just trying to see out front from the cockpit. Just like the real Spitfire.
 
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#15
Full scale Spitfires were design to takeoff from large grass aerodromes and so cross wind takeoffs and landings were not much of an issue since pilots could choose to line up with wind in almost any direction. But with paved runways, cross wind takeoffs and landings make the plane very tippy to the sides as the landing gear geometry just is not designed to take much side loads. Additionally, like most WWII warbirds, it's very susceptible to bounces during landing flare, unless touched down in perfect wheel landing or 3 point attitude. But boy, does it perform in the air!

Line of sight flight performing airshow aerobatics:

 
#16
Onward to installing FPV system in the Spitfire. It was more time consuming than I thought. Compared to other 1400 mm span warbirds, this Spitfire has a relatively compact fuselage. With a large 6S4000mAh battery taking up almost all space under the forward battery hatch and another 3s500mAh battery used to power the FPV system taking up the rest in the forward fuselage. All FPV equipment was installed in the cockpit and space behind it - adding 5oz of weight. To counter balance and retain previous CG, additional 8oz of weight was added inside the cowling. Internal scaffolding was also built to hold VTX away from foam to effectively cool it during flight...

Time to test out the FPV system in flight by giving friends FPV joy rides while I fly it line of sight.

 
#18
Hope you stick with it! RC flying hobby has so many interesting aspects that are very rewarding to explore. And finding challenges and trying to overcome them is at least half the fun - that’s what FliteTest is all about! Flying FPV pretty much doubles the flying experiences/challenges for all the planes I have. I no longer fall for having to get the latest and greatest each time a new plane comes out. Something to consider when you decide whether to buy a new plane or invest in FPV equipment....
 
#19
Forward visibility, really wasn’t that great in the previous joyride video, especially in waning light and with sun in face on final approach. Need to try one more with better lighting conditions and see if I can see enough to make safe flight ops under FPV.


Conclusion: I might be able to fly FPV with this configuration, but certainly not enjoy it. Clarity of front glazing simply is not enough to see other planes clearly in the air. Need to cut the clear part out and use the framing only.
 
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Kananga

Active member
#20
It would be nice to see a thread on making a head tracker system if your goggles dont have it built in.
I like the idea of headtrackers but I've only got a set of fatshark predator 2 goggles because back then i went for price instead of shopping around for quality and felt trapped by them ever since (if only they got stolen or irreparably broken lol).