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Futaba 8UAF and Tamiya R/C tank - programming question

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Old 05-13-2003, 01:41 AM
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JWLaRue
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Folks,

I am trying to figure out if it is possible to use a computer radio (in this case a Futaba 8UAF) to control my 1/16th Tamiya Tiger tank.

This tank kit includes electronics that piggy-back the gun function onto the gun elevation channel. This allows a simple 4-channel radio to be used. The manuafacturer notes that the way to access the gun function is to slide the joystick trim slider switch all the way to one extreme...and then quickly flip the joy stick to the full position.

This works on non-computer radios like the Futaba Skysport, but (apparently) not with my 8UAF.

So my question: is there a way to use the programming feature(s) of the 8UAF to "de-couple" these two functions? (elevation and gun firing) I'd like to set up one of the toggle switches to mimic what I *think* is a servo overtravel condition...which would appear to then allow the gun to be fired.

Any and all suggestions will be welcomed!

Jeff
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Old 05-13-2003, 03:53 PM
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cwright
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Default 8UAF

Jeff, although it is possible to use the 8UAF for the tank, the radio you have is for aircraft use only. You would have to get a transmitter on the 75 mgh band to be legal, as this is for ground use only. Your 8 channel is on 72 mgh for aircraft use only.
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Old 05-13-2003, 04:02 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

The 8U uses RF modules... As long as he uses a 75Mhz module it's OK.
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Old 05-13-2003, 04:59 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

I appreciate the advice, but why do you assume that my 8UAF has a 72MHz rf module in it?

Not that it makes a difference with respect to the programming aspects of this radio, but it already has a 75MHz rf module in it. (I've also got a 50MHz module and receiver)

-Jeff
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Old 05-13-2003, 05:53 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Jeff,

You may find one or more of these Futaba FAQs applicable to your situation:

http://www.futaba-rc.com/faq/faq-bots.html
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Old 05-13-2003, 05:58 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Hi Bill,

Many thanks for the pointer to the FAQs...unfortunately, they do not address my particular 'problem'.

-Jeff
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Old 05-21-2003, 03:46 PM
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Default Any help?

...one last bump to see if anyone can help me out!

-tnx,
Jeff
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Old 05-21-2003, 03:57 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Do you have to program it on one channel? Can you have the elevation on one and the fire control on another? I know that seems too easy, but I haven't done a tank and don't understand why they would make it as hard as it sounds.
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Old 05-21-2003, 05:25 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

I believe that Tamiya (Futaba) used a single channel to combine the gun elevation and two gun firing operations so that they could make use of a 4-channel radio.

In looking to use my 8UAF, I don't mind using some extra channels as part of the programming exercise to 'de-mux' the functions.

...hope that made sense!

Jeff
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Old 05-21-2003, 06:53 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Still not sure how it works. You have one servo moving the elevation, but I missed how it fires. Is there another way to put a micro servo on the fire control. You stated that you needed more throw from the sounds of your first post, unless I miss understood it, but you can program your ends on the 8U or move them to 140% so you should have more throw than with a non computer radio. Is there a way to bypass the box they made for the 4 ch setup and use a servo to fire instead of the box they made to piggy back a channel?

Sorry to ask so many questions about it, I don't undersand how they make it fire and am trying to figure that out so I can be of more help.
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Old 05-21-2003, 07:01 PM
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Default mix

Set a mix to do it.

I assume you are trying to get additional travel on the same channel. In other words the tank is set up to move the gun elevation and then fire when the travel gets past a certain point?


If so, just use a PMIX to mix the channel into itself. The normal movement of the stick moves the gun, when you get to the highest elevation, flip the switch, the mix kicks in and you fire.

Hope that helps, if not just ignore me
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Old 05-21-2003, 08:16 PM
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Default ...almost! But not quite....

The Tamiya-supplied electronics don't actually use servos. There is a module that is used to connect the receiver and it, in turn, is used to connect to the various different bits like motors and LEDs.

The idea of using a PMIX id what I've been thinking might work, but I don't want to have to elevate the gun 100% before being able to fire the gun.

What I'd like to be able to do is the set up a switch such that it gives me an immediate overtravel on the given channel. I *think* this would mimic how the electronics work today.

-tnx,
Jeff
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Old 05-21-2003, 08:23 PM
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Default OK

You could do that on a (ZAP, but I am not sure on the radio you mentioned.

The 9ZAP has a flight condition, with one switch you could change everything in the radio, including all of the ATV settings, subtrims etc. Or you sould literally drive one channel from 2 controls, one the stick and one a switch.

Also there are other electronics around that will do this on the reciever side if you want to go that way.

Good luck
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Old 05-21-2003, 09:00 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

You can get more travel using say the flaperon function. It makes the aileron function move to full, then you dial the flap function to get more travel. Don't know if that will work for what you are doing though.
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Old 06-07-2003, 02:55 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

I am using a 7UAP to control a tank. I found a similar problem when I switched from a 4-channel non-computer FM radio to the 7UAP - here is how I fixed the problem.

For me, the machine gun worked but not the cannon, so it was easier to figure out what was wrong - I knew it was 'possible' and not a limitation of the radio. I just set the ATV to 120% for the direction of the cannon. It works great now!

Sounds like you need to set the travel higher than 100% in both directions on channel 3, since the machine gun isn't working for you either.

If you figure out a way to split the servo lead to channel 3 so you can use another channel to fire the guns, post away! might be an expensive mistake if that doesn't work and fries the MF-01 though. : )
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Old 06-07-2003, 03:01 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

That's excellent to hear!

What switch did your tie to the 120% ATV? I'm assuming that you've got the radio configured so that you fire the gun independently of moving the main gun (elevation).....

-many thanks,

Jeff
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Old 06-07-2003, 03:56 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

It's still the barrel elevation stick - exactly like it worked on your 4-channel non-computer radio. (just like it says in the manual, in other words.)

I have the barrel movement and guns on channel 3. I can fire the machine guns or the cannon without moving the barrel.

I was interpreting your post as saying "I just want to use the 8UAP, I don't care if it still only uses 4 channels." I am saying that your 8UAP will work exactly like the 4-channel non-computer radio you previously had connected.

If you are asking "how do I get the guns to fire using a different channel or switch?" I don't think it is possible. Tamiya programmed the guns to work on channel 3 in the extreme servo-overtravel condition. If you slide the trim up and then slowly move the stick up to elevate the barrel, the cannon won't fire. you have to "flip the stick" fast. So programming something else on your Tx, like a mix, is just going to elevate the cannon, isn't it?

I was trying to decide if it would work to splice the servo 3 leads and also send them to another channel on your Rx (assuming you have more than a 4-channel Rx). But I don't see how it would work! I don't think it would send a signal fast enough to trigger the firing logic. I think that the barrel would simply move to the end of its travel.

If you used channel 5, which has no "centered" position, the machine gun or the cannon would just keep firing if it worked at all. If you used channel 6, you'd have the same manual process to fire - you'd have to flip that knob fast in one direction or the other. You gain nothing - the joystick on channel 3 would actually be easier to use!

What we need is for Tamiya to decide that enough people are using 6+ channel radios with ground modules (75 or 50mhz) to justify programming the MF-01 to allow you to assign the cannon and machine guns to a separate channel other than 3. Fat chance IMO. Production costs would be too high to change the MF-01 now. They can't even get a 5th tank on the market!
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Old 06-07-2003, 04:21 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

Incidentally, if anyone knows how Tamiya programmed that module to sense what JWLaRue calls an "immediate overtravel condition," or a way to have the Tx send a signal like that, please post.

As a further explanation to those who know a lot more about RC than I do and have posted in this thread, but don't have a tank, here is a little clarification. Simply sending a signal like a channel 5 "landing gear" signal would not be enough. The guns only fire when you flip the stick fast. In other words, the guns don't fire just by sending a servo signal to the end of travel in either direction.

You have to set the trim slider switch all the way up (or down) and then flip the stick fast in that direction. I mean FAST! if you slide the trim up and then move the joystick up at normal speed, the barrel simply elevates and the cannon won't fire.

Tamiya did this because ground frequency radios usually have 4 channels or fewer. These tanks will work with a 2-channel radio, although you can't roll and fire at the same time if you only have 2 channels.

The 4 channels are for throttle, steering, turret rotation, and barrel elevation. Tamiya was pretty clever to figure out how to add the ability to fire two different guns independently of those four functions and still use only 4 channels! The computer inside the tank can apparently sense a signal spike in the over-travel positions on channel 3. Simply sending a "slow" signal on channel 3 will move the cannon barrel up and down but won't fire the guns, regardless of where the trim dial is. Freaky huh?
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Old 06-07-2003, 06:46 PM
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Default Futaba 8UAF and Tamiya R/C tank - programming question

I wasn't really thinking of trying to use any channels beyond 1-4 for this.....but I hadn't thought of using the ATV with a quick flip of the stick.

There is a 'conversion' that can be done to the 4-channel Futaba radio to allow the guns to fire with swirches. Check out:

http://www.fragarmor.org/Advanced%20Hints%203.htm

Some of our local group of folks have done this and it works well.

It's this type of switch-based activation that I'd like to get working with a computer radio (e.g. 8UAF).

btw: the Tamiya electronics are reported to be made by Futaba....

-many thanks,

Jeff
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