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how fast is a Quadcopter...Tricopter

#1
like the title says how fast is a Quadcopter...Tricopter i Never thought of it until now because a friend asked me and i had no idea "so a improvised answer it's fast enough" -))
i'm building one based on HK X550 Frame with
Prop Drive 28-26 1350KV / 310W Motors
TURNIGY Plush 30amp Esc,s
Carbon Mixed slow fly 9047 Props
Nano-tech 4S 35~70C Lipo
And a dji naza-m lite Controller
This is my firs build (so i hope this is a good set up)
 
#2
well my quad running the following has topped off at 70km/h while following a plane and 65km/h while going low and fast

motors : turnigy dst-1200
prop : gemfan 9*4.7
esc : hk f20a simon k flashed
fc : kk2.0
battery : zippy compact 2700 25c


 
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#3
Dam i never figured them that fast...and thanks for the answer as well as the Awesome videos
NOW i really must get my build done Can't wait to start flying
 

Cyberdactyl

Misfit Multirotor Monkey
#4
Oh. . . I freely admit my racing quad is designed for full or close to full throttle for optimum drag efficiency. The planform direction presents the least amount drag to all components.

I suppose if you want as little drag as possible in all frame relative directions, x, y & z, you should use round tube booms, and keep all parasitic and practical mass as close to the CG and polar moment of inertia as possible.

Below is based on a 450-600mm quad.

Keep all power and control wiring inside the booms. Directly associated with keeping all mass at the center, you DO compromise by having three power leads instead of two going from the frame to the motors. A compromise of added mass I believe is worthwhile. Also choose relatively large and high KV motors ~1200-1600, and provide them realistically high voltage (4S) and high discharge rates >90c. And a CF prop of 9-10" with a fairly deep pitch of 6.

I believe a +200kph/hr is possible. Of course you'll need someone with the talents of Warthox to hold it at full throttle for more than a second or two.
 

squishy

Pirate ParkFlyer
#5
I have reached 100km/h with my 4 cell quad..There are some very real limitations to overcome still, it's in the flight controller...
 
#6
can you estimate what my quad would be capable of (if i get it right) i'm never build an aircraft before so i have no idea what to expect when or if it will fly at all -)
 

squishy

Pirate ParkFlyer
#7
in manual mode you will easily reach 40mph about (60kmh) maybe 50 (80kmh), even in alt hold mode...but not in gps mode..
That's fast enough for anyone that needs to ask the question...
 
#8
The fastest quads I've seen on youtube tilt out well below 200km/h - I think it was around 150km/h(?). I don't know where the speedrecord is but reaching the speed of sound on your bladetips may be an issue to figure out as well :) .
You may also consider the flightcontroller side. I would go for some gyro only flight mode ("acro") with a high lowpassfilter turned on (20Hz, or 10Hz if its flyable, 5Hz seems to low). More stabilized modes using ACC could lead to trouble because it is hard for the AHRS to determine the direction of gravity when pulling G or having unavoidable vibration levels at high speed. That will be highly dependent on the software/datafusion/filtering/physical model/further sensorintegration (like MAG) etc. used by the FC.
Just guessing here ... my quad tilts out at 60km/h (gps speed) :) .
I am keen on what numbers come up here in this thread....
Cheers
Kraut Rob
 
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#9
i was never thinking how fast because People have just been talking about how much they can lift and flight time..but yeah this may be a handful for me ....you got that one right :D
 

Cyberdactyl

Misfit Multirotor Monkey
#10
Yes. If you attempt high velocity with the z axis of the multirotor anywhere near 90 degrees to the direction of travel. . .or some angle close, you have to include forward speed to the rotor tip speed and see if it is approaching a sonic velocity by multiplying the cosine of the angle for whatever the props are off parallel.

However, turn the multirotor's z axis in-line to the direction of travel, then you only worry about simple tip speed. That's where a fairly deep pitch (>6) will be an advantage. Of course there may be a bit of sluggishness at lower rotor rpms.

And to be honest, I'm not sure how simple FC boards like the KK2 would handle somewhat large, deep pitch props at lower hovering rpms.
 
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#11
Warthox claims 148km/h here http://fpv-community.de/showthread....it-von-Coptern&p=310009&viewfull=1#post310009 on his "small" setup (1.1kw/kg) but has not measured his 1.8kw/kg setup - that seemed faster to him. He is using multiwii in acromode. I googled around and couldn't find anything useful on how to design a multicopter speedbeast. Perhaps an more aerodynamic design and tilted motors? How many motors? Just KW muscle? I really don't know.
The next thing will be measurement. 2D GPS speed or airspeed or speedgun....or...? What would a simple gps logger do? Measure 3D GPS speed - then a freefall would produce the best result :) .
Greetings Rob
 
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Cyberdactyl

Misfit Multirotor Monkey
#12
His quad is very fast.

But I believe his design is still far short of providing a minimal platform using those electronics and similar frame stiffness. I'm speculating the drag can be reduced by another 15-20%.
 

Cyberdactyl

Misfit Multirotor Monkey
#14
He did streamline the central hub with the dome, and he is using small square wood dowel or CF booms. But he still has his wiring in the wind stream and in the thrust column and his ESCs are turned flat in planform. Turning the ESCs 90 degrees alone would reduce the drag by 5-10% or more. His design has no consideration for the low pressure bubble his quad is making on the back or trailing edges.

Very few, if any, multirotors designs to date attempt to minimize drag in the planform view. Most, if not all, attempt to achieve a streamlined frame in the elevation view since they fly lateral to the elevation view 90+% of the time.
 

Cyberdactyl

Misfit Multirotor Monkey
#17
Speaking of tip speed, the relatively new Sikorsky X2 is a wonderful example of using a co-axial and somewhat short rotors, to balance the need for lift and to the need to stay under sonic velocities on the forward rotating tip and/or exceeding the foil design.

It is genius to use short bladed co-axials to balance that loss of lift to the opposite sides of each disk. Since it is a simple co-axial with a lateral prop, and not a craft with any real lift surface, I suspect somewhere under 340kts it would simply begin to sink.