FPV Coota Sea Plane - 930mm

Details

 

About

I bought this from my friend who purchased it from Hobbyking.com model named "COOTA" a Sea plane.  Re-branded from the original manufacturer ART-TECH.  Made from lightweight, brittle and 'denty' EPS foam which makes the overall airframe extremely lightweight and floaty which means it breaks like icebergs if you crash one so not good for beginner platform.  The wings are are longs compare to the length of its stubby fuselage. Thrust from a pusher prop, removable landing gear which means its not steerable but works great taking off from water.  Despite its cartooned midget looks and being functional amphibian plane it does fly as good as a glider and inherit similar flight characteristic as my SKY SURFER.  At the end of the wing tips are small "anhedral" contrary to popular glider type "dihedral" wing tips.

The reason it was converted into FPV is because it have surplus left over of nano size FPV hardware and thinking having put putting on it for the sake of being curious about how it fly and view from it.

 

 

Model specification & setup

Airframe type: Scale low winged sea plane
Branding/Manufacturer: ART-TECH
Model name variant: COOTA
Material build: EPS foam
Wingspan: 930mm
Length: 680mm
Stock airframe weight: 428gram
Full FPV flying weight: 670gram
Aileron: 2x 9g servo
Elevator: 1x 9g servo
Rudder: 1x 9g servo
ESC: 20A
Motor: DAT850/850kv
External BEC: UBEC 5V/5A
Propeller: APC style 8x5"
Radio receiver: Turnigy 9x 8ch
Radio receiver antenna: Stock Omni
Battery: 1x 1000mah 3s 35c
Center Gravity: 1/3 from the front leading edge of the wing.

 

 

My DIY FPV specification

Camera: 520 TVL CMOS mini (5v)
Secondary camera: None
Camera pan/tilt mechanism: 1x 9g HXT900 (180 degree mods) pan only
OSD: HK Simple OSD
Flight Control board:  None
Video transmitter: Boscam nano 5.8ghz 200mw (1s)
Video antenna: DIY tuned Clover Leaf
Battery: 500mah 1s 25c

 

Building

The FPV installation and issues are similar to "SKY SURFER" setup as i previously build before.  I'm not going to key in  the same comments repeatedly about this setup you might probably click HERE (SKY SURFER) to check the build and read all about it.  The only differences between them is Cloud Fly have extremely narrow cavity inside the fuselage, almost barely able to fit in 2200mah 3s 25c lipo into the front nose without cutting out the extra foam.  Fitting remaining components such as OSD/GPS and Radio receiver is also very tricky because the only remaining cavity access to place this parts are blocked by two rudder and elevator servo at the entrance.  Caution during the build is that this ariframe is actually very sensitive to weight placement.  Best keep full flying weight is max 1.1kg.  More than that it will never hover very well and the stall speed tolerance will diminished into uncontrollable "Spiral of Death" problem.   Most ESC and BEC are located inside the fuselage, you'll need to poke bunch of hole on the black canopy cover to let the cool air in to cool them down.  Based on my flight experience Cloud Fly have the highest percentage possibility of "Brown-Out" situation where BEC module doesn't have adequate amount of cooling because the heat is trapped inside its narrow fuselage.

FPV building level difficulty/rating: Medium (7/10)
FPV equipment setup grade: Basic
Building hours required: 5 hours
Skill required: Soldering/Foam cutting
Critical issues during installation: None
Required additional mods/must do improvement: Canopy cover magnet needed to be re-glue else will fly off during flight.

 

 

 

FPV flight characteristic and performance

Once it took off from the ground it flies like a magic carpet and it actually feels like one.  It doesn't like to go at full throttle else would nose up all the time probably due to the pusher prop angle and waste all power because this one is a slow flier.  It hover almost STOL pace when the craft is exactly leveled both on 'Y' and 'X' axis provided it gain minimum recommended speed and during landing there no need to pull high "AOA" like any typical plane does probably because of the wing design and anhedral tips does wonderful work to level things up.   It sometimes does tail wagging like the infamous ICON A5 models when there's an abrupt wind turbulence.  Overall flight i didn't encounter any fault in handling, it tracked well, banked well, smooth ride all the way home.  However its not suited to be a perfect long range flight given the fact its a slow flyer at recommended max speed of 45~55km/h on  1000~1300 3s 35 lipo pack which runs at safe run-time of 25 minutes.  Another cons is this platform is not a good altitude climber,  it just like to keep itself best leveled at 250m which is optimal at cruise speed not sure why probably stock power limits its ability i guess. If it does climb it would took forever to reach 1 meter starting at 250m level.   Contrary being a bad climber however COOTA excel best at close ground proximity flight, hover best and stable at 30~50m height so its a best platform to hover around the tree canopy, fields and over the ocean without a glitch.  Caution being anhedral wing tips because it will slip off size ways to wing "wash out" because its non-dihedral wing design, you'll need to counter the banking with slight rudder.  Anhedral is good for slow maneuverability, manual tracking and STOL landing just like how my A-10 flies.  Yes my HK Warthog A-10 EDF jet have the same flight characteristic like COOTA does especially those smooth straight line landing.


Minimum level of flight experience required/flight-hours: Intermediate(65 hour)
Nature of platform handling experience/skill required: Scale plane - Low winged
Self leveling capability in thumbs-off stick situation: Yes  at 20km/h>>
Take-off & landing difficulty: Medium (Yaw issue)
Hand launch: No
Max speed: 45~km/h
Min speed before stall: 15~20km/h
FPV flight/radius: 800m max (given above FPV spec/setup)
Max altitude: -
Bail-out/fail safe recovery altitude limit: 50m
FPV safe distance range for testing: 600~700m (Open field)
High angle of attack (AOA) tolerance limit before stall: 25 degree at 20~25km/h
Ground "STOL" (Short Take Off and Landing) capability/thrust%: Takeoff 10m (80%)/ Landing 4m (15%)
Altitude climbing power/thrust%/AOA angle: 20 sec/per-meter at 70% thrust/15 degree
360 degree turning radius clearance/holding pattern: 10m
360 barrel roll/loop acro flight: Yes (but not recommended, loose canopy)
Control expo - aileron: 45% (low to high)
Control expo - elevator: 45% (low to high)
Control expo - rudder: 45% (low to high)
Control end point - aileron: 75% (low to high)
Control end point - elevator: 100% (low to high)
Control end point - rudder: 100% (low to high)
Flight time: 25~30 min
Ground spotter visibility (LOS): 350~600m

 

 

Safety issue

I can't find anything wrong with this guy nor anything serious being potential hazard.  The only minor issues is blown off cockpit canopy and the light flimsy plastic motor motor case above it because those are hold on by magnetic locks.  As far as i know it not suited to fly long range beyond distance of  800~900 meter due to inadequate power supply to return home and safe altitude to clear the RF interference/ radio transmission bounced on the ground or inadequate altitude for fail safe recovery. The basic nano FPV equipment fitted above isn't going to get any good range.  Fitting the same FPV equipment from SKY SURFER or AXN Cloud Fly will bunk the weight limit and worsen the handling.

 

 

Pros and Cons

Here are list of pros and cons about this platform. Some of this are needed to take seriously if you are going deep into long term FPV ambition

Pros:

  1. Extremely light airframe.
  2. Huge fuselage cavity to fit FPV equipment.
  3. Excellent STOL landing at almost hoverable at low altitude thanks to anhedral wing tips.
  4. Its a "pusher" propeller driven plane, video recording and pilot viewing is not obstructed by spinning propeller unlike "tractor" type propeller in front of the nose.
  5. Minimal impact risk with ground object because the light weight foam will shatter first because it causes more harm and the crash speed is slightly lower between 10~18km upon impact.  IT would likely to glide or leveled if there's no power or in "dead-stick" situation thanks to its air-foiled boat hull surface under the belly which almost provide dihedral stabilization.

Cons:

  1. The flimsy plastic canopy will fly away exposing innards and reduce aerodynamics.
  2. Need longer runway or full thrust to takeoff due to low wing distance the ground.
  3. Tail wiggle during turbulence flight, it wiggle like a dog tail upon countering side wind something similar to ICON A5 r/c airframe problem.
  4. Non steerable landing gear, standby counter the yaw with the rudder control at full speed take-off.  No issues steering in the water.

 

 

Current status & flight history

The purpose of this build because i was being too curios about flying inside the COOTA, having surplus of nano sized cheap FPV hardware so i decided to take a bite and build one for fun.  I got the frame cheap as 2nd hand and with surplus of hardware why not.  The first day of flight till the end of it flight service it fly well without any flaw.  COOTA is best flown FPV at club field, a park flier and sea side cruising above the water at least 30~50m min clear from public and private property. May not be able to go far or high but just enough to enjoy the joy of flying above the trees and path finding on the country side or big open field.  Throughout the build COOTA didn't have any recordable HD quality video but only once for live DVR recording from my FPV Ground Station, so you should able to view sample of my flight review video on board FPV COOTA on Youtube via my 3DXL channel.  COOTA flight service short lived and the airframe was donated to our field buddies who are in need.

 

Lifespan operation: 4 months
Maintenance priority check: Canopy cover magnet + motor mount
Constant critical issue: None
Maintenance cost per-lifespan: None
Flight hours accumulated per-lifespan: 53 hours
Best L.O.S distance record: 0.8km
Est. distance covered per-lifespan: 450km (Odo)
Best height record: -
Best flight time record per-session: 30min (1000mah 3s 35C)
Best low hovering speed record: 10km/h
Best record  for zero thrust landing distance/power failure glide recovery distance: None
Activity status: Retired (mid 2012)
Reason of retirement: Fun experimental just for fun due to surplus FPV equipment.

 

 

Summary

11COOTA is a fun flying platform geared for relaxing slow FPV flight.  Zero maintenance, zero worries provided you don't push too far or too high on stock basic grade FPV hardware and power.  Best to describe it as a "flying carpet".  Despite all those good news about its handling caution required that Low Winged flying experience is need to handle this little guy.  Best if you earn few flight experience on scale winged platform such as the "Super CUB" or "CESSNA" before you get the feel on COOTA because of its twitchy aileron banking handling and need to gain perfect scale like rudder control during flight.  Buying a COOTA from original manufacturer ART-TECH is not cheap because its flying quality worth the price. Usually they come with their own unnecessary radio gear which i you don't need much for quality FPV flight.  The best place to find a re-branded  version is from Hobbyking.com where the price is slashed half without the radio transmitter and you get a good reliable PNF (Plug and Fly version) with their own logo but traces of ART-TECH trademark can be found etched on hidden places.  Happy flying.

 

 

Videos/Medias
MediasHere are some of my video and gallery related to the above topics:

 

 

 

 

 

 

Shopping list

Here I've listed some raw material, hardware and stuff where you can start building your own FPV platform.  The list contain the above hardware and also include some compatible ones which you can pickup what suits best for your need and your budget.  So come dig around and start your tech flying ambition:

  1. Platform/Airframe:
  2. Radio set/combo:
  3. Motor/ESC/BEC:
  4. Servo:
  5. Camera/HD/DVR:
  6. Flight controller/AP System/OSD:
  7. Video transmitter/combo:
  8. Battery:

 

 

 

Building threads/Referral

If you don't know where to begin with i recommend you to start reading some guides, wikis and building tips from popular on-line resources as listed below.  You might find me hanging around some popular R/C and FPV forum below.

 

 

 

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