Transmitters and Receivers

matelot · Posted: Fri Jul 20, 2012 12:31 am Post subject: Transmitters and Receivers

Hi, guys,

Being out in the sticks in France, and no club nearby, I'm reliant on this forum and search engines, so bear with me. Trying to get my head around tx's/rx's, and their compatibility across the various makes.

For example: chopper A has rxA installed and is supplied with txA;

chopper B has rxB installed, but I buy txC (which comes with rxC) because it's recommended;

I acquire chopper C, already have txA and rxD.

How does the compatibility work? Subject to voltage (and what else?), can any chopper take any rx, and/or is that dependent on having the same make of tx?

Will a Walkera tx work with a CopterX rx. Will a KDS K-7 tx work with a T-Rex 450 rx?

There are so many options with combos and kits, with and without transmitters/receivers/motors and other add-ons, that it's a bit confusing. Then throw in all the cheap stuff from HK... I'd like to understand the permissible permutations in an effort to source a good deal - even if it means mix and match.

Cheers, peeps.

ferretmaster · Posted: Fri Jul 20, 2012 1:49 am Post subject:

In a nutshell, any brand of Rx/Tx will work in the MECHANICS of any helicopter. This is assuming they will fit, as some micro-helis are built around the Rx.

Where you cannot mix is the TX and Rx from different manufactures (with the exception of the Hobby King "Orange" series of Rx that work with Dx series of Tx, I believe)

As a general rule the Tx and Rx must be the same brand (both Walkera, or both Futaba etc.)

The voltage for the Rx is the only concern and again, almost all run on 5v to 12v BEC's just fine! The Tx will have it's own power supply and voltage varies by model even within the same manufacturer

Hope this helps!!

matelot · Posted: Fri Jul 20, 2012 4:23 am Post subject:

Many thanks, Dave. That explains a lot.

So now it's a question of future-proofing. Quite a few in the price range come with a tx/rx:

KDS 450 (K-7x), T-Rex 450+ (Futaba), Blade 450 3D (DX6i), CopterX V3, Walkera V450 FBL, Genius 500 - all with tx. And clearly some are better than others.

I'll keep at it. Many thanks again. Very Happy

matelot · Posted: Tue Jul 24, 2012 8:44 pm Post subject:

Supplementary question:

If I build a 450 FBL with a 3 axis flybarless gyro, would there be any disadvantage in using a 6ch tx e.g. DX6i? Or is there a distinct advantage in going up to a 7ch or 8ch?

It's a cost consideration as bumping up the channels means more spondulicks on an exponential scale.

Cheers

tombo242 · Posted: Tue Jul 24, 2012 9:11 pm Post subject:

Hi John,

I think the answer here depends on what you want to attach to the heli. I have heard of people using the 6 channel 'Orange' Spectrum compatible Rx (same as I put in some of my helis,) but with the CPs' there are no spare channels. Therefore, if you want to drop bombs, have nav lights on/off or fire guns, then you will need the extra channels. Otherwise 6 are enough for a 3 axis gyro.

(All info gleaned from 3rd party sources, accuracy cannot be guarenteed.)

Tom.

matelot · Posted: Tue Jul 24, 2012 10:13 pm Post subject:

Many thanks, Tom. That'll do for now. Some kits are going with the Devo7 or a K-7 (KDS 450), but the Devo 7 isn't getting good reviews (too close to redundancy?)

Then there are other combos with a Devo 10 (sounds like it needs a generator to power it...) Laughing

Perhaps too big at this early stage.

Cheers

Cock145 · Charging Joined: 20 Jan 2015 Posts: 1

There are so many options with combos and kits, with and without transmitters/receivers/motors and other add-ons, that it's a bit confusing. Then throw in all the cheap stuff from HK... I'd like to understand the permissible permutations in an effort to source a good deal - even if it means mix and match.

http://www.test-king.org/CCNA-Voice-Certification.htm
http://www.coloradocollege.edu/
http://test-king.org/
http://www.lynn.edu/

Burgess · Extreme 3D Joined: 27 Mar 2012 Posts: 1103 Location: Wales

Hello Watson and welcome to the forum.
Well let's see your looking for good helicopter and radio kit at a reasonable cost.

A six channel 3D capable helicopter is more akin to a formula racing car than a domestic run about. So attention to detail and maintenance is important, without which they can be a whole bunch of vibrations, held together with threadloc, CA glue, and hope. A properly setup and dialled in helicopter is easier to learn to fly with than one that's not.

I hope the following doesn't add to the confusion, just pointing out some things to take into consideration.

Besides the helicopter and the transmitter you will need ancillary equipment.
#1 jewellers scales, blade balancing equipment, pitch gauge (I prefer to use two); these are needed to balance the rotor blades and doing the blade tracking. You will also need a rig for checking the balance of the main rotor head assembly. Very important for the rotor head to be perfectly balanced.
#2 LiPO discharge indicator cost very little, and a good quality balance charger such as the iMAX B, and a Watts meter; these are needed for the power train management; also soldering equipment and an AVO meter.
#3 Not forgetting blue threadloc, green bearing fit, and CA glue.

Helicopter:
The non-running stuff -frame, boom, fins and skids, etc., not exactly a fuselage more of a chassis, rank lower than the mechanical and the electronic stuff. So a barebones kit is probably more economical than purchasing individual components.

Mechanical transmission train: all things that spin and mesh,
bearings, shafts, and gears, all these need to run concentrically to minimise vibrations. If you go for a T-rex 450 clone barebones kit, then close inspection of these components for dynamic concentricity. If any run out of true (probably will) replace them with Align components.

Main rotor: CNC alloy heads look great but with low end priced components, microns out here and there, and the head just doesn't balance properly. Plastic components have consistency come out of the mould the same time after time, more resilient, lighter, and cost less to replace. A 3mm feathering shaft provides more teeter moment in the rotor housing, and this facilitates easier cyclic handling.
In a barebones kit check the mixing-arm bearings for side-wise lost motion and the link-rod eye to link-ball fit which needs to be slop-free. Flybarless main rotor systems are mechanically less complex than a flybared head, however, they do need a 3-axis gyro control system, so more expensive than a flybared rotor.

Main Blades: Carbon fibre ‘D' box construction are stiffer than GRP encapsulated wooden-cor construction. Most blades conform to NACA 000 section 10% thickness foil section. The reflexed variant, I believe perform better than standard 000 section blades do. These needn't be expensive, many good inexpensive carbon fibre blades are now sold in matched numbered pairs. Avoid cheep pseudo CF foam filled blades they have a maximum safe operating RPM that's too low for modern 450 helis.

Servos: The servos are doing all the important stuff, cyclic servos need to be strong, quick, accurate centring, with minimal lost motion (slop) so avoid the cheapest.
The tail servo, needs to be strong, fast, accurate centring, and digital, paired with a good MEMS gyro.

So Cyclic Emax ES09D, Rudder ES9257 paired with Assan GA250 MEMS Gyro.

Power train: ESC, motor, and battery, need to be a matched set.
The ESC, ideally needs to be programable, to provide a soft start, cut-off voltage, and timing to suit the chosen brushless motor.

The Motor, needs to be optimum for the flying style, kv (revs per volt), current draw, volts, and watts rating.

The battery constant current and burst current ‘C' ratings.
The constant current output needs to be higher than the current drawn by the whole system, -that includes power for the receiver, servos, gyro, and motor- during maximum throttle opening with the motor under load.

Radio transmitter:
The Internet's your lobster: You need at least a good entry level helicopter capable six-channel self contained programmable transmitter. Most popular systems are:
2.4ghz FHSS [frequency-hopping spread spectrum] and DSSS [Direct Sequence Spread Spectrum]

Here's an interesting article and video:-
http://www.rcmodelreviews.com/fhss_vs_dsss.shtml
If you intend to join a local RC heli flying club arrange a visit see what their requirements if any are.
This video gives a simple comparison of the two systems.
https://www.youtube.com/watch?v=DoRU47vbRuc
I use a 2.4ghz FHSS transmitter, other pilots on this forum use 2.4ghz DSSS transmitters.

Important Read-up on LiPO battery care, here is where discipline pays off. Airborne discharge indicators have green and red LEDs when the first red shows stop flying that prevents over discharging any cell. Always store at storage voltage 3.8v per cell, here store means over night and the batteries will give you long service.

Here's an example based on a T-rex450SEV2 Clone with moderate power, enough to see you through the learning curve.
Note: [Item prices may vary when accessed from you location.]

Giant shark.co,uk
chassis HK-450MT Fiberglass/Plastic Helicopter Kit.............£18.88
Motor KA450H 3200kv 24A 266 watts 3.17mm shaft...........£ 8.42
{Needs a 13t pinion}
Banggood.com
ESC Hobbywing SkyWalker 40A ESC With UBEC..............£ 8.77
EMAX ES09D Digital Swash Servo For 450 Helicopter........£ 4.75(X3) £14.25
EMAX ES9257 25g Digital Servo......................................£ 7.88
HobbyKing.com
Gyro Assan GA-250 MINI-MEMS Gyro..............................£ 8.35
LiPO ZIPPY Compact 2200Mah 3S 11.1v 35C....................£11.19
....................................................................................Total £77.74

Radio kit
Turnigy TGY-i6 AFHDS Transmitter & 6CH Receiver (Mode 2)......£32.34
Or
Radio link T6EHP-E FHSS Transmitter 6CH & Receiver (Mode 2)...£38.19

Align.co.uk
Up grade with Align components
Autorotation tail drive gear-Black HS1220AA....................£ 3.82
Main Gear set of 3 HS1219QA..........................................£ 4.94
Main gear case & One-way bearing HF0612....................£ 8.76
Metal Tail Drive Gear Assembly H45099.......................... £ 5.78
Tail Rotor Shaft H45100 set of 3.....................................£ 5.39
.............................................................................Total £28.69

All in ................................................... from £138.77 to £144.62
Plus any delivery charges from each company

Burgess