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Fast Tricopter FPV Platform

#1
I have been asked to do the video footage for large scale jets, 1/4 scale and larger. Obviously a tricopter is far to slow but I want to fly "chase" for maiden takeoff and landings. What makes a tricopter fast? I am looking at using the Batbone or Turnigy Talon with Gopro hero 3.
Which would be faster?
More stable, using a kk board as standard??
Thoughts, advise???
 

xuzme720

Dedicated foam bender
Mentor
#2
Multi's in general are speed limited by the same factors heli's face in terms of airspeed, short answer, airspeed on the progressing blades. (There's a lot more to it than that, but that's another whole series of articles.)What makes multi's go fast(er) is smaller dia props with more pitch and a motor/esc/battery combo to handle the pitch heavy props. The frame shouldn't be much of a factor except in it's overall weight.

I did have a thought though. If you are flying FPV you could hang around in the middle of the pattern and just do small circles to track the jets while they are flying. You wouldn't need anywhere near their speed but sadly, it wouldn't be as dramatic as the close quarters air to air footage it seems we'd all rather have.
 
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Cyberdactyl

Misfit Multirotor Monkey
#3
Multirotors have the capability to be extremely fast.

Far and away the limiting factor for most designs is giving no attention to planform and thrust column obstruction. The majority of people don't push a multirotor into high velocity regions where those design limitations greatly restrict the performance. As I'm sure you have already seen, when speed is considered, only the battery, motor and prop are considered and a passing interest in how those effect mass.

I also considered flying configuration in my racing quad (in this category section). Flying in true + config, the quad presents less planform to the airstream as it transitions closer to the horizontal (planform parallel to the horizon) flight (right), where X config presents close to double the air resistance (left).

 

Carbon

Elemental Madness
#4
I would suggest the Bat Bone no matter what you want to do. The Talon is known for having very little space to mount electronics :)
Higher KV motors and higher cell count will get you speed.
 

xuzme720

Dedicated foam bender
Mentor
#5
I guess I was thinking in terms of ful scale heli's where the body IS streamlined, both for forward flight and in the thrust column direction, and so the main limiting factor is the progressing rotor blade nearing/reaching mach 1 in fast forward flight. Since most multi-copter frames are usually limited in cross section, wind resistance didn't even occur to me. It should have, since air doesn't scale...but I also don't usually fly my multi's into that end of the envelope. I keep them relatively slow, shallow end of the pool, so to speak.
Thanks for the correction and insight!

Given these new insights, something with round or more streamlined booms would be even better. Cyberdactyl had another great idea for his racing quad which used carbon heli blades for booms to further streamline the frame.
 
#9
http://www.radiocontrolinfo.com/RCcalculator/AirplaneCalculator.php#WL
use the prop calc at the bottom to find your motor kv and prop for optimum speed.
ultimately they alone will dictate how fast you can go. im not so sure i can buy into cyberdactyls quad theory but he may be right. a tricopter flys fast with a nose in attitude which will point your cam toward the ground to be prepared to adjust accordingly with a tilt mechanism.
youre also dealing with a double edged sword...speed eats batteries so the faster you go the shorter your flight time will be, offset with a bigger battery and your adding more weight into the equation. keep this in mind.
you could always rig a forward facing high kv motor to the tri for all out speed you could gain alot in this way with a very small motor, maybe above the very rear of the batbone frame. this motor wouldnt even need to be connected to the kk just run it off your rx and a spare channel mixed to a vr switch.