Is there a stand-alone main/tail mixer board on the market?  
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All Forums >> RC Helicopters >> Electric RC Helis >> Is there a stand-alone main/tail mixer board on the market?
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Is there a stand-alone main/tail mixer board on the mar... - 7/30/2004 6:32:39 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		Hi all,

anyone know if there is a stand-alone mixer board on the market that could mix main and tail signals?

Seems to be the missing link with the separates setups.

Most people seem to just let the HH gyro battle the torque to keep things straight and have the tail signal left mid way throughout all the throttle settings. Mixing on the tx is out of the question on the HH gyros so the only logical solution is to mix the throttle and gyro output signals and feed this into the tail ESC.

Anyone got a solution for this?

Perfect setup would to be able to measure the main rotor rpm and use this is the reference to mix with the gyro output to drive the tail ESC levels. Remove lag mixing issues that way.

Oi! GWS! there's an idea for the PHA-02! (oh, and throw in some sensible heat sinks)


Also, I noticed that there is a "Humming Board" that I assume the Hummingbird heli uses. Is this just a mixer or is it a combo ESC mixer for main and tail?

< Message edited by eheheh -- 7/30/2004 7:05:57 AM >
       Post #: 1

RE: Is there a stand-alone main/tail mixer board on the... - 8/2/2004 4:15:45 PM   
marked23



Posts: 377
Joined: 3/2/2004
From: Lynnwood, WA, USA
Status: offline 		Most people go separates because they want to use a brushless motor. I haven't seen a brushless main / brushed tail mixer board anywhere.

Using a HH gyro without any mixing at all is totally normal. This is how it is done on the nitro helis too. HH gyros are really "set it and forget it."

If you use a HH gyro, stop looking for a mixer. You shouldn't use one. If you have a rate gyro, you can do your mixing on your radio... presuming your radio has multi-point mixng curves.

BTW, My hummingboard seemed to do a better job of mixing than I could do with my radio. However, that may just my programming.

-Mark

(in reply to eheheh)
       Post #: 2

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 1:14:09 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		Yes but on nitro heli's the tail speed is directly proportional to the main rotor speed due to a mechanical link between the two. No mixer needed on board.

And no, you cannot do main to tail mixing on your transmitter if you have any form of Gyro in your heli as the signal to the gyro will change every time you apply a change to the throttle channel. Every time a gyro senses a change on it's input signal is eases off on trying to correct which leads to odd behaviour on the yaw (wagging most of the time).

The mixing on Heli Tx's deals with Throttle to Pitch mixes on CP models and Revo mixing which applys small changes to the tail pitch on heli's that use a mechanical link to the tail rotor from the main motor. The Revo mix corrects the torque changes when the pitch of the main blades are changed. Heli setups on TX's are not designed to work with heli's that use a separate electric motor for the tail.

Hence the advice from most dealers that you should use a standard aero Tx for these types of heli's.

With electric heli's that use a separate motor for the tail the removal of the mixer throws all rotational ratio's out the window.

I'm not saying that the heading hold gyro cannot do the job at all without a mixer. I'm saying that to get it to work you are setting it up to counter torque outside of where you decide to set the yaw channel when it is centered. The yaw channel in the mixless setup remains in one position the whole time unless you apply a forced change on the transmitter. With this setup you have to get the yaw channel set to a position as close as possible to having the tail straight in a hover and any variances in your flight behavior which fall outside of this balance will cause yaw due to torque will ends up getting tackled by the gyro. Add to the fact that the tail will be running when you have no throttle input and you have to set the yaw input on the Tx to zero for a couple of seconds to allow the tail ESC to initialize.

The mixless setup with HH is like flying a heli with a constant blast of wind on the tail. The gyro will be constantly battling to keep a heading when you move into anything other than a stable hover.

For the sake of the exercise I will be getting a GY240 HH gyro this week and I will be hooking up two separate ESC's. Initially there will be no mixer. All behavior of the heli will be documented in this configuration. Then to compare I will go back to the PHA-01 (2 ESC's/Mixer/Gyro), set the gyro gain to it's lowest, hook up the GY240 between the PHA-01 and the yaw channel on the Rx and document the heli's behavior with this configuration.

Now if I had one of these new CyberCopter's which function the same way as the nitro heli's mechanically (main-tail direct drive link) then a HH would be one very happy camper.

Hey, somebody has to explore this configuration as I don't think it's been investigated so far from what I have been reading.

Guess the proof is in the pudding...we'll see what works the best with the real thing rather than just theory.

(in reply to marked23)
       Post #: 3

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 5:58:56 AM   
marked23



Posts: 377
Joined: 3/2/2004
From: Lynnwood, WA, USA
Status: offline 		Hmm.. Ok.

So what you are saying is that this could improve tail stability with a HH gyro?

What if it's already perfect, with just separates and a HH gyro. Then why bother? The gy240 will hold great, mixer or not.

-Mark

(in reply to eheheh)
       Post #: 4

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 6:49:08 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		Hi Mark,

can you please confirm the following:

A) your heli uses a separate electric motor for the tail.

B) you are using two separate ESC's and a GY240 connected between the yaw channel cable from the Rx to the tail ESC.

C) you have not set up any mixing of any sort on the Tx.

D) the tail remains in exactly the same spot from standing still on the ground, to hover and then during forward flight when you are not applying any deliberate yaw.

E) when you do apply input to the yaw channel the heli rotates cleanly and sharply without any wobble in either direction.

If these are rock solid facts for all points then I'll stick my theory on the mixing issue in the bin and not give it another thought.

Regards,

John

(in reply to marked23)
       Post #: 5

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 7:02:59 AM   
Mhale71


 

Posts: 647
Joined: 10/8/2003
From: sydney, AUSTRALIA
Status: offline 		uh oh, i have an ep concept sr, that flys well, i also have a gws dragonfly that just needs electronics, i thought the pha-01 whas for this?

_____________________________

Hooah!

(in reply to eheheh)
       Post #: 6

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 7:26:26 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		Fear not say I! The PHA-01 is fine if you have a few weeks heli experience behind you. It's just a bit of a bugger to find a balance on the mix setting so that the impact of heat build up is not as noticable in the first 5 minutes after the electrics are cold. I actually completely removed the dicky plastic cover off the board on the weekend and that has reduced the drift in the mix substantially. Just stuck the double sided tape directly to the large IC on the back.

I'm yet to prove that if you introduce a heading hold gyro between the yaw channel on the Rx and the PHA-01 with it's own gyro sensitivity all the way down that you get the tail perfectly straight under all flight conditions.

Stay tuned.

(in reply to Mhale71)
       Post #: 7

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 7:34:10 AM   
marked23



Posts: 377
Joined: 3/2/2004
From: Lynnwood, WA, USA
Status: offline 		I've been working on building a good separates setup for about a month now. I finally came up with something that is suitable for use, yesterday. My main mistake was using the wrong tail ESC. From reading other posts, the GWS ICS-50 and CC Pixie-7p are both good. I use the GWS ICS-50.

A. Yes
B. Yes, Two separate ESCs. One is brushless, the other is brushed. Gyro is CSM HLG200. Fut gy240 should be equivalent or better. Your choice of tail ESC matters a lot.
C. Yes, No mixing in the radio... HH gyro will not tolerate it.
D. Long answer:
Exactly? No. But I haven't tuned my gyro gain yet. [I've flown just one battery on current setup.] It might. At my current gyro gain setting (about middle) I get a bit of torque induced drift during a sharp (very sharp) climb out. It drifts 20deg and then sticks right there. Perfect? no. Useable? Totally. I think a bit of fine tuning on the gyro gain can cure this. Nominal climbouts are perfect. There is one single wag (30deg) when the heli leaves the ground, as the gyro spins up the tail motor. In forward flight it is rock solid. In turns, it's solid. There is absolutely none of that spinning around business even on full power launches.
E. Yes. I can do fast or slow piros in both directions. When I center the stick, the tail stops... always. Sideways, forward, backward flying.

Here's my full setup: (copied from another post)
Hummingbird v.II
eFlite Park 370 Brushless
Phoenix-10 Brushless ESC
GWS direct drive tail motor (CN12-R-??)
GWS ICS-50 tail ESC
GWS 3020 tail prop
CSM HLG200 gyro (yes, the gigantic blue one. I'm going to lighten it... It's way huge!)
Thunder Power TP1320-2SJ 2-cell Lipo

That being said, I still wonder if a mixer would be helpful.

-Mark

< Message edited by marked23 -- 8/2/2004 11:51:41 PM >

(in reply to eheheh)
       Post #: 8

RE: Is there a stand-alone main/tail mixer board on the... - 8/3/2004 11:49:25 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		Yes, I read a number of posts saying the Pixie 7P was the go for the tail .... that's what should be turning up at my front door tomorrow.

It certainly sounds like the HH gyro's can tackle quite a bit of the issues of not having a matched main to tail rpm ratio from your own experiences but as you said in point D it's not 100% perfect with the inital swing of 20 or 30 deg. The PHA-01 and GY240 combo test will act as a performance test/comparison. If I'm lucky and find that it is as stable as the setup you are using but without the inital swing of the tail then I might be onto something here.

If that looks promising then I might sit down and come up with a circuit diagram that can mix two Rx signals at 5 different points (for added accuracy). And while I'm at it I may as well look at using a pulsed input from a sensor that can measure the RPM of the main rotor and use that as the guide for determining the tail signal levels. With this little board it could be used with separate quality ESC's to fairly much simulate having an actual mechanical drive connection to the main rotor like most heli's use.

Eh, who knows, GWS (or someone else) might very well come out with a far better all-in-one board some day soon that can deal with all this.

(in reply to marked23)
       Post #: 9

RE: Is there a stand-alone main/tail mixer board on the... - 8/4/2004 3:21:22 AM   
Jerrykl720


 

Posts: 179
Joined: 2/26/2004
From: Toronto, ON, CANADA
Status: offline 		http://www.zebrahobby.ca/cgi-bin/cp-app.cgi?usr=51F3409291&rnd=3860754&rrc=N&affl=&cip=67.70.95.57&act=&aff=&pg=prod&ref=Heli-042&cat=heliElectronics&catstr=HOME:helicopters:heliElectronics

(in reply to eheheh)
       Post #: 10

RE: Is there a stand-alone main/tail mixer board on the... - 8/4/2004 4:21:19 AM   
eheheh



Posts: 145
Joined: 7/15/2004
From: SydneyNSW, AUSTRALIA
Status: offline 		I assume the FD-042 is the dual ESC/mixer board that originally shipped with the DF heli when you had the separate PG03 gyro.

Preferably a mixer that has no ESC's would be good for people who have gone out and obtained good quality separate ESC's. Unfortunately I don't think they exist.

< Message edited by eheheh -- 8/4/2004 4:23:05 AM >

(in reply to Jerrykl720)
       Post #: 11

RE: Is there a stand-alone main/tail mixer board on the... - 8/4/2004 10:13:18 AM   
thiswillfly


 

Posts: 41
Joined: 3/17/2004
From: Wolverhampton, UNITED KINGDOM
Status: offline 		I went seperates on my stock aerohawk using a CSM HH gyro and have been dissapointed with the results. With the absence of any tail mixing the tail is constantly fighting the main torque and is noticeable with tail wagging. Have tried all gain settings and the gyro is mounted correctly. I'm using a pixie 7p main and GWS 100E tail.

My theory had suggested this would happen but had hoped it would be ok in practice - wrong!. HH gyro's work well on nitro heli's 'cause the tail drive is fed from the main drive and is therefore the equivalent to electronic mixing. HH gyros are designed to remember and keep the nose pointing on a set heading - they do this by detecting and reacting to movement exactly like a standard rate gyro does - hence the same sort of problems if there is no mixing.

Fortuantly there is an answer to this - but more money!. (I'm still trying to swallow cost of HH gyro at moment). That is to use a TREC ESC which mixes throttle to the tail motor and is fully programmable with gain and throttle curves etc. Cost is about $60 but this will sort the problem and the tail will be under full control as it should be. Will be getting one of these when I can.

(in reply to eheheh)
       Post #: 12

RE: Is there a stand-alone main/tail mixer board on the... - 8/4/2004 4:46:39 PM