Ok, so I am relatively new on this forum.  I am looking to build a quad for chasing high speed car races that is efficient yet powerful enough to maintain high speeds for longer durations than my 5", which I definitely feel struggles to keep up speed and hammers the battery.  The only direction others have given is the Catalyst Machineworks Merica 9", which I am not against (in fact it looks like a great setup), I guess my main concern would be props in view on the GoPro but not sure at what angle it would pick them up, or a few random 7" rigs.... But I just wanted to see what others opinions are on this.

SO, what would be your choice setup for chasing racecars???
READY!?!?
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5inch is the sweet spot about performance, get close to a car in a corner accelerate next to the car... if you like to go close to cars, 5inch power is needed and its not too efficiency.
a lightweight 5inch build is better than a common heavy freestyle quad.

if speed-efficiency does matter more than responsiveness to get close to the car, 6inch does improve it that.

while 9" will have a higher on high speed, it suffers way to much in response. 7-13inch does give to much mass, mass where a racecar will outperforms in cornerspeed and acceleration/decrease speed.


aslong as you like to fly in a range of 5m next to a racecar, 5inch is the size.
if the racetrack is very high speed, with loong corners; if the speedlevel stays high like in nascar racing, 9-13" might get benefical.


the special focus of fpv is close to the object/car, my advice is to go for a more lightweight 5inch build or for 6inch to improve efficiency without or low amount of downsides in responsiveness.

I have a Merica 9” and I can tell you its not very agile in the corners like a 5”. You have more lipo capacity but its not by that much.

You can work around the props in view by mounting the camera and gopro at a higher angle but then the footage is not very cinematic as the yaw movement is different and not aligned well with the centerline of the quad.

Question remains do you need to capture an entire race from start to finish? You can get away with multiple 5” quads and lots of lipos for the most part.

One thing to mention here is that 9” is expensive, the props are like potato chips and the lipos are expensive and crashes are costly in terms of repairs and it’s scary flying them around people (both for the pilot and spectators).

I am capturing footage for an oval track, stock cars and modifides, kind of like Nascar, just a shorter oval. It's only a 1/3 mile. New London Waterford Speedbowl in CT. I like the responsiveness of the 5" when the cars are on a caution lap, where they are going slower and waiting for the green flag. But once that flag comes and they hammer it I feel I am struggling to keep up and killing the lipos hard. This isn't drifting where I have to be nimble to change direction every second. For the most part it's high speed around an oval essentially. Granted most of the quads are generally more freestyle oriented and not typical "race drones". I'm thinking somewhere in the 7"-8" range would be more beneficial as far as flight time and average throttle position to keep up, without losing all types of maneuverability. Next race is June 11 and doubt I can build and test a rig in time so my 5" squadron will have to do again. Just thinking for the future I guess....

The problem is that most 7" quads are built for endurance rather than speed.

Not saying you cant make them go faster by using higher KV motors such as 4S motors on a 6S lipo but how much more flight time will you get due to the heavy battery load.

But 7" can be the sweet spot balancing speed/efficiency/price between 5" and 9" giving you the best of both worlds if built for your requirements.

Yeah 7" isn't going to be as nimble and easy to tune as a 5", but it is what it is right? 5" ain't keeping up, and 7" may be the better tool for the job. Just make sure you don't do the 5" conversion thing (what I like to call it) where you take a heavier 5" setup and slap it on 7" frame and props... or you'll get the all too common result with a 6s1300 sagging low, fully saturated 23xx motors dropping efficiency, poor flight times, and all that just to end up with rig that's less nimble than 5". Instead, pick motors and lipos that are sized up to handle 7". Something like 2808 1500kv and ~6s2200mah on hq7040 triblade (don't forget the larger 4in1 like 65A) is a solid setup that's becoming more popular with folks flying aggressive 7" these days. Your short oval application I think qualifies as aggressive flight (compared to an LR flight profile anyways). With something like that I think you will easily be able to keep up at the short track. Flight times won't be what most people expect out of 7" (LR), but they'll be a little longer than 5" freestyle for this I bet.