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Venom › Night Ranger 2 Brushless/Separates Upgrade
02-10-2008 06:27 AM  10 years agoPost 1
hypoxia88

rrNovice

western australia

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After burning up 15 main motors and 20+ tail motors I finally bit the bullet and did the brushless separates modification.
Components used:
ESky EK5-004 3100kV motor + 9tooth pinion $25.00
Walkera WK-WST-10A ESC $23.00
Hitec HFS-05MS receiver $35.00
ESky EK2-0702A HH gyro $55.00
GWS ICS-50 2A ESC for tail motor $22.00
Hitec Optic6 transmitter - used for Twister3D

General configuration:
Separated wiring - all power wires LHS, all servo/signal leads RHS, ferrite ring fitted to main motor ESC power/signal lead.
Hitec HS-55 servos
Paddles painted white and balanced (paddle visibility is important as the paddle disc indicates the direction the heli WILL be moving once the control input acts on the main blades)
Stainless steel flybar (less flex than CF = quicker cyclic response, unbreakable)
No flybar weights - quicker cyclic response
Strengthened DF4#1 blade holder (top filled with epoxy and laminated with 2 aluminium plates 1mm apart - no flex thus quicker response and less coning of main blades, unbreakable)
Strengthened rotor head pivot/guide ring (CA glued 4 strips of CF, unbreakable)
Aluminium tail boom with blade strike protection strip (CA glued length of fuel line along strike zone, unbreakable)
Nyloc nut blade bolts - precise tension for running loose blades
Main blades balanced - same weight to +/- 0.01grams and same C of G, no vibration
Main blades weighted on tip - two adjacent strips of two layers of white insulation tape on tips (top and bottom) gives loose blades the inertia to self align, as well as increasing the visibility of the blade disc (orientation advantage) and protecting the blade tips
Main frame reinforced from tail boom mount to drive shaft - almost unbreakable
800mAh battery mounted high (on top of Al plate extension - weight placed closer to the C of G enhances cyclic response due to reduced pendulum stability)
5mm ball fitted to rear boom spike - minimises digging in, tends to skid.
Knighthead (flag on rear boom) removed to assist rear rotor air flow.
The heli has a neutral balance.

AUW = 284g (including 800mAh Lipo battery)

Initially I tried a 3800kV inrunner brushless motor with a 10t pinion. It had good power and very quick acceleration but ran hot (75 degC +/- 5 deg) and drained the 800 battery to 7.2v in 5 minutes, heating it to 50 degC in the process. Flying with an ambient temperature of 28 degC, the ESky 3100kV outrunner with a 9t pinion heats to 35 degC by the end of a battery with the battery reaching 37 degC and the ESC 33 degC.
Draining the 800mAh battery to 7.2v consistently flies the heli for 10 minutes (+/-1) and recharges 600mAh (+/- 40). Less heat = more fly time!
Throttle curve 0,60,100 - heli hovers at mid stick; general forward & backward flight, re-entries and funnels rarely need more than 3/4 stick. Full throttle will jump it from the floor to the ceiling in less than a second.
Optic6 is used on normal flight mode for most flying, IdleUp1 (ST1) for experimental changes in D/R, Exp etc and IdleUp2 (ST2) for all times other than initialisation and flying. After ESC and gyro initialisation the tail motor tends to run (sometimes v fast) until left rudder input is given. ST2 rudder is trimmed to -50% which inhibits the tail motor. ST2 throttle curve is set 0,0,0 for safety.
The heli flys beautifully - plenty of power, cyclic response and tail authority. (EXP settings for cyclic controls are +90% & EPA 80% for general flying, EXP +100%, D/R 125% for flat out twitchy hot-dogging). The tail motor stops turning on anti-clockwise piros .... and the clockwise piros are mental! The BL ESC could have better throttle resolution and the HH gyro/tail motor ESC could be better, but all of them are cheap and light and perform adequately (better than the standard 4 in 1). The ESC driven tail motor should have a much extended life due to the reduction/elimination of voltage spikes. The BL motor maintenance should be reduced to pinion change outs. The Hitec receiver has been glitch free, unlike the 4in1 that glitched at the drop of a hat (or the turning on of a high efficiency light globe, microwave, mobile phone, set top box etc etc)

WEIGHT is the biggest enemy of the FP heli - a 10 gram increase in weight is noticeable. With any increase in weight the heli becomes far less responsive due to the increased gyroscopic stability and coning of blades. Flight times diminish dramatically due to the extra work being done as the blade lifting and dragging forces increase - hence the law of diminishing returns associated with larger (heavier) batteries. Dynamic stalling of blades is also increased but gyroscopic precession is decreased. The main reasons bigger (heavier) helis are easier to fly are the increase in gyroscopic stability, decrease in gyroscopic precession and increase in pendulum stability.
I love flying indoors and am tempted to build an RollsRoyce ultra light FP, but it would cost more than the MiniTitanE325 I want to add to my fleet, so ........
Final conclusions
I wish I had done the conversion in the beginning. It would have saved lots of angst caused by glitch crashes and motor replacement after motor replacement after motor replacement after ........
It would have also been cheaper - maybe that's why the LHS does not promote it.

Future project
LIGHTEN IT - shorten wires, lighter motor (hover at 80% throttle), lighter servos?, reduce head stiffener weight from 5.5g to ?, smaller blade retaining bolts, lighter paddles, lighter flybar, change velcro mounting of receiver and gyro to thin strips of double sided tape, reduce amount of tape on blade tips, change battery & receiver mounting plate from aluminium to ?, trial 400mAh battery (30 grams), lighter canopy (present canopy has 4.5 grams of repair tape & CA glue repairs), remove covers off receiver & gyro & rear of servos ......... or just FLY IT!!

My strong recommendation is that if you are flying a FP heli, have worn out two main motors (and a few tail motors) but just love flying your FP heli indoors (at any time day or night, rain or hail, 10 knot winds or hurricane tempests) AND can not see a time when you won't be flying it ..... JUST DO IT!

ps I don't get on the forums much (prefer to spend my time flying!) so you will get a quicker response from me on hypoxia88@hotmail.com

Reference: http://www.helihobby.com/html/separate_electronics.html

"dare to be great"

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