RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

How many channels is enough?

Reply

Old 02-16-2003, 01:48 AM
  #1  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

How many channels do you absolutely require to be fully proportional that drive control surfaces? I'm wondering what the minimum number of proportional channels would have to be in order to give you full acrobatic control out of your craft. Don't count ganged servo's or retracts or anything that can function on a switch channel or a slower proportional channel. Just full rate proportional channels.
Lynx is offline  
Reply With Quote
Old 02-16-2003, 01:56 AM
  #2  
Mighty Mik
Junior Member
 
Join Date: Dec 2002
Location: Berkeley, CA
Posts: 23
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Control surfaces?? I have some of those, but i also have drive trains and weapons as well.
Mighty Mik is offline  
Reply With Quote
Old 02-16-2003, 02:12 AM
  #3  
theox
Senior Member
 
Join Date: Jan 2003
Location: N.Chicago, IL
Posts: 275
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

2A+2F+1R+1E=6

For some reason I can only get this out of 7 chanel Txs.
theox is offline  
Reply With Quote
Old 02-16-2003, 02:27 AM
  #4  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

There are so many answers depending on the situation, maneuver, and the effect you are going for.

Simple aerobatics could be done with 3 channels. More advanced aerobatics require 4 channels. Various flight situations, and stuff like 3D flying, could require from 4 to 8 channels if you start adding in spoilers and flapperons sometimes used for harriers, elevators, and splitting and separate mixing arrangements for offset elevators, crow setups for various diving maneuvers, etc.

Also, if you are flying the larger planes, even the basic aerobatic setups sometimes use multiple channels on the same function for technical reasons, even though you may only be setting up for standard and/or 3d aerobatics.

It really depends on what you mean by 'full aerobatic control', and depending on what size airplane you have.

Not knowing, I assumed standard aerobatics, with a mid size airplane, and voted for 4 channels as the absolute 'required' number per your question.
sfaust is offline  
Reply With Quote
Old 02-16-2003, 02:40 AM
  #5  
Flyfalcons
Senior Member
 
Flyfalcons's Avatar
 
Join Date: Jul 2002
Location: Bonney Lake, WA
Posts: 6,544
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

I'll go with 5, just because using two channels for ailerons opens up flaperon/spoileron mixing possibilities.
Flyfalcons is offline  
Reply With Quote
Old 02-16-2003, 07:05 AM
  #6  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

I'm wondering why they don't make transmitters cheaper and more standard and move the advanced mixing functions onto the receiver. Given most of the channels over 4 aren't actually used for control of the aircraft they're used for mixing various functions. If you could move all that stuff onto the receiver you free up 4 extra channels, which in PPM could double your responce rate of control inputs to the helli, and in PCM mode would increase the amount of redundant data that could be sent to asure signal quality. No more than 4 control inputs need super high constant refreshing (the ones that directly control flight) things like air ele rudder and throttle, gears, any other options you could possibly think of could be sent as an on demand signal instead of a constant one. Ganging and mixing done on the receiver frees up all those channels. You'd end up with a 200 dollar xmitter, and a 200 dollar receiver that could function as well as the 1000 dollar radio rigs people out there have. The processing power for dealing with this kind of stuff is not exactly exotic, neither is the electronics required to make them function, and with modern microcontrollers you can program more mixing functions than you could possibly imagine. That and I can't figure out why so many people think you absolutly have to have to have a bazzillion channels on the radios
Lynx is offline  
Reply With Quote
Old 02-16-2003, 07:08 AM
  #7  
Flyfalcons
Senior Member
 
Flyfalcons's Avatar
 
Join Date: Jul 2002
Location: Bonney Lake, WA
Posts: 6,544
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

So get some Matchboxes for all your multi-servo needs.
Flyfalcons is offline  
Reply With Quote
Old 02-16-2003, 02:31 PM
  #8  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by Lynx
Given most of the channels over 4 aren't actually used for control of the aircraft they're used for mixing various functions.
This is your error. While the absolute minimum is 4 channels required, that doesn't mean additional channels aren't being used for control surfaces, or used other devices that need to be proportional.

In a large aircraft, I use all 10 proportional channels for a variety of reasons. I typically use 7 for the main functions for A, E, R, T. I also use a smoke pump that requires proportional control for volume adjustment. I also have a ignition kill switch with a has a glitch counter for PCM radios, and it relies on proportional control for its setup. Thats 9 proportional channels.

I could setup the same airplane to use only 6 channels if I used matchboxes, or Y's, or as you suggested some mixing on the receiver end if that was available. However, there are other essential non control functions that require the use a proportional channels, not to mention many features that we all have become accustomed to that would require some proportional control from the transmitter.

I voted in the poll for 4 channels because you asked for the 'minimum number of proportional channels required for aerobatic control.' Had you asked for the minimum number of proportional channels I would require for setting up aerobatic airplane, the answer would be been somewhere between 7 and 9 for the reasons above.
sfaust is offline  
Reply With Quote
Old 02-16-2003, 02:41 PM
  #9  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by theox
2A+2F+1R+1E=6

For some reason I can only get this out of 7 chanel Txs.
Did you try hard enough??

And lets not don't forget the Jets. With the added channels for the ECU's, Gyro, proportional brakes, variable smoke systems, separate nosegear steering, etc. I used up all 10 channels in my Bobcat, and if I had to reduce the number, I would be hard pressed to do so. And it used a Y for the dual elevator and rudder servos, or I would have more channels.

It would be rude to leave them out just because we were only talking aerobatic airplanes and its channel requirements. We need to look the entire industry if we are going to start messing with reducing the number of proportional channels.

But then, come to think of it, since they are giving me/us the snobbery attitude that I can't fly 'regular' RC airplanes during open flying after hours at FJ, well, heck. Lets just go to 4 channel radios, or at least reciprocate and no longer allow jets at any non jet event :boxing:
sfaust is offline  
Reply With Quote
Old 02-16-2003, 08:27 PM
  #10  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

You only need full time refresh on 4 though. The others can be sent as on demand signals (only when they actually change) because they're not instantly time critical to keep the Helli in flight, and aren't used 90% of the time. You could double the refresh or resolution of the standard 4 if you sent the other 6 channels you hardly use like that. Dual Rates and Expo help smooth out control movements, but nothing does it better than actually increasing your ability to control those surfaces.
Lynx is offline  
Reply With Quote
Old 02-16-2003, 08:39 PM
  #11  
Flyfalcons
Senior Member
 
Flyfalcons's Avatar
 
Join Date: Jul 2002
Location: Bonney Lake, WA
Posts: 6,544
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by Lynx
Dual Rates and Expo help smooth out control movements, but nothing does it better than actually increasing your ability to control those surfaces.
Set up a DP Extra with 3D rates and no expo. Take a video, because I'd like to watch.
Flyfalcons is offline  
Reply With Quote
Old 02-16-2003, 10:59 PM
  #12  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by Lynx
You only need full time refresh on 4 though.
I don't think that is true. Unless the manufacturer decided to do away with things like flapperons and spoilers, you need extra channels for these functions, and they need full time refresh to perform properly. Add in some of the interesting setups with dual elevators being used as dual elevators and on demand switching them over to elevators for certain maneuvers, and that again would require more than 4 channels being fully proportional.

What about twins, with dual throttles. You don't want to mix that function, as you need the mixing and asymmetrical function to tune the engines properly. Although, this could be done with a matchbox type function embedded in the receiver. But again, what about the Jets. They need 4 proportional channels for the control surfaces, and usually another 2 to 4 full resolution proportional channels for gyro sensing, nose wheel steering, ECU aux control channel, and proportional brake control. If they want to use the nice proportional smoke pumps, they need at least a 1/2 or 1/4 resolution channel for that as well.

If we were only given 4 proportional channels in the beginning, with the extra channels as non-proportional or on-demand, we would have made due. However, with more than twice that available to us now as fully proportional channels, there would be a large outcry for taking those away from us.

I personally can not see any way they could convince me to buy any radio with less than 9 or 10 fully proportional channels. Even if they could get the resolution up to 50,1024 for each of those 4 channels, I wouldn't' budge. In fact, most pilots can not tell the difference between 512 and 1024, so increasing the resolution won't impress many people, but only get them mad if you took away the other proportional channels in the process.

Ain't no way. Now or ever. The next radio I will buy will have MORE than 10 proportional channels, not less.
sfaust is offline  
Reply With Quote
Old 02-17-2003, 12:48 AM
  #13  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Not the resolution the refresh rate HUGGGGGGEEEEEEEE difference. Standard RC uses a 50 hertz refresh rate. That's a minimum of .02 seconds after you hitting the joystick on your xmitter to the aircraft actually being able to do anything not to mention encoding and decoding time. Doubling it would turn that into .01 seconds. It's difficult to tell how pilots would react to the difference because it can only be experienced hands on.
Lynx is offline  
Reply With Quote
Old 02-17-2003, 12:57 AM
  #14  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Yes, you're right. I read resolution into your reply somehow.

To me, its one of those things that I'd have to experience to see if it makes any difference at all. One would also need to take advantage of high speed servos to get the full benefits. It could be minor, but then again, it could make a big different in experienced hands.

I'd love to try it! (but not at the expense of my other channels )
sfaust is offline  
Reply With Quote
Old 02-17-2003, 12:58 AM
  #15  
Geistware
Senior Member
My Feedback: (16)
 
Join Date: Apr 2002
Location: Locust Grove, GA
Posts: 12,942
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

I need 2 for each control area, so it will be 2 aileron, 2 elevator, 2 rudder and 2 engine. 8 Channels is my requirement.
Geistware is offline  
Reply With Quote
Old 02-17-2003, 01:30 AM
  #16  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

And if you look at the suggestion that Lynx mentioned, you would still have your 8. However, 4 of them would be mixed and setup on the receiver, and thus would not need to actually use a channel transmitted from the transmitter.

For example, you need two channels for each servo on the elevator. However, all you need to transmit from the transmitter to the receiver, is to either move the elevator up or down which only takes 1 channel to do this. The other channel used is pretty much a duplicate of the primary elevator channel save the end points and sub trim. The receiver would then take that command, and split it into two channels out to the servos. You get the benefit of two channels in the airplane, but only need one channel link between the transmitter and receiver.

We currently do this with the matchboxes, where we take one channel, and turn it into 4. All the ATV's, and sub trims are set in the matchbox, and not on the transmitter. If the manufacturers incorporated the functions of a matchbox into the receivers, we could easily get more channels, or higher refresh rates on the primary channels, etc. Lynx brought up a good point, but for a different reason being refresh.

I would leave our current refresh alone, and just allow more channels at the receivers end. Viola, we now have 12, 14, 16 or more channels at our disposal.

We can actually do this now with 4 matchboxes if we desired. But, if they made a smart receiver, where you have the standard 10 channels, but also had an additional 6 channels locally mixed to a primary master channel (ail, elev, rud, th), and have it configured at the transmitter and downloaded to the receiver, that would alleviate us from having to use transmitted channels, which are basically duplicates of the primary channel.

Hmmm..interesting thoughts Lynx...
sfaust is offline  
Reply With Quote
Old 02-17-2003, 07:00 AM
  #17  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

That's exactly what I'm talking about, I can't figure out why manufactures don't do this. The latest PCM receivers on the market cost 200+ dollars. Futaba's 9Z costs what, 1200 dollars with servo's? 800 or so without? Meanwhile you can go to Ratshack and pick up a handheld about the size of the palm of your hand that can send and receive on 2m and 70cm bands at up to 5 watts for 269.99 and there's no crystals to screw around with. 2-4 microcontrollers to do all the mixing at about 40 bucks a crack, and that's retail with a healthy price markup, the industry costs of the equivalent effort would be minuscule after r&d costs.
Why is the RC industry still so backwards? Given how close 2 meters is to the 72Mhz band RC users use, why the are we spending this kind of money for inferior products? It's a pet peeve of mine. I don't mind spending money, I do mind spending too much money for what I'm getting.
Lynx is offline  
Reply With Quote
Old 02-17-2003, 07:22 AM
  #18  
Flyfalcons
Senior Member
 
Flyfalcons's Avatar
 
Join Date: Jul 2002
Location: Bonney Lake, WA
Posts: 6,544
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

I think there are many people that would argue with the idea that what we have these days is inferior. The benefit of having many channels is the flexibility to either use them to slave surfaces/servos together or to actually use them to accomplish different tasks. I like being able to control the servo output from my transmitter, rather than a receiver that I just stuffed into a plane. I can also use inexpensive receivers with my nice transmitter and still get the results I want, rather than having to purchase some receiver/matchbox hybrid that would most likely top 300 bucks. I just don't see a mass change of radio design so people can get their servos to move .01 seconds quicker.
Flyfalcons is offline  
Reply With Quote
Old 02-17-2003, 02:27 PM
  #19  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by Flyfalcons I like being able to control the servo output from my transmitter, rather than a receiver that I just stuffed into a plane. I can also use inexpensive receivers with my nice transmitter and still get the results I want..... [/B]
I agree with you about not loosing the functionality we have today, and leaving the refresh alone.

However, the manufacturers could use the receiver/matchbox hybrid design to increase the number of channels, and leave all existing functionality as is. You would still be able to use your transmitter just as you would now with the cheaper receivers today. However, if you purchased a new hybrid receiver with more channels (say 14 or 16), the transmitter would then be used to program them, and download the info to the receiver. I would appear no different to the user, but technically, things would change on the receivers end since they wouldn't be true channels, buy matchbox equivalents embedded into the receiver.

Technically it could be done, but at what price, and with the matchboxes already doing this, how big is the market? Mostly those who run ganged servos and use matchboxes today. Rather small in light of the entire market.
sfaust is offline  
Reply With Quote
Old 02-18-2003, 01:03 AM
  #20  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Considering the cost of todays high end transmitters which could be reduced by a large factor by increasing the intelligence of the xmitter/receiver I'd say the market would be huge if you told people they could purchase something that was the price of a Futaba 9C with capabilities greater than a 9Z if they only spent 50 bucks more on the receiver... Wouldn't anyone agree to that? The technology exists, it just needs to actually be implemented by companies. Problem is they won't put forth the initial cash investment to develop them. The innovations currently going on in the RC world are baby steps compared to what could be done with what's out there now if they just tried. How long have crystals been used in RC equipment now? Why? PLL technology is so advanced now it has as little drift on a synthesized module as even the best tuned crystal oscillators, maybe even less so, because crystals are subject to vibration damage. A freegin 39.95 walk-man is digitally PLL tuned from 88 to 108Mhz. So why are synthesized receivers so expensive? I could see RC receivers costing up to 50% more than a comparable standard FM radio simply because the bandwidth limits are tighter, but other than that... And if you think about the markup on those Walkmans you'd be astonished at how much this stuff actually costs.
Lynx is offline  
Reply With Quote
Old 02-18-2003, 05:02 AM
  #21  
sfaust
My Feedback: (11)
 
sfaust's Avatar
 
Join Date: Sep 2002
Location: Boston, MA
Posts: 1,900
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

Originally posted by Lynx
capabilities greater than a 9Z if they only spent 50 bucks more on the receiver... Wouldn't anyone agree to that?
It all depends on how many receivers one buys. 1 transmitter and 1 receiver, I'd have to say yes. But, $50 times 6 or 8 receivers wouldn't be attractive, and with my inventory of receivers, I'd surely loose money.

No, I wouldn't go for that at all. Although, I do like the idea.
sfaust is offline  
Reply With Quote
Old 02-18-2003, 09:11 AM
  #22  
Lynx
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Rochester, NY
Posts: 1,373
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default How many channels is enough?

They could be designed more modular for people like you, so the receiver could easily be transfered between planes. As long as you can access at least 1 side of the receiver you could make it pluggable in a base station. Not to mention they'd have to be scalable to some degree (high end and low end units) I'm not suggesting final solutions here really, just new ideas.
Lynx is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service