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Old 11-13-2010, 09:30 PM   #1
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I am: Klint K
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programming two engines into DX8

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I am trying to program my two engine Cessna 310 into a DX8 with AR 7000 Rx.

I am trying to use the Throttle channel for the left engine, and AUX 1 Channel for the Right Engine so that I can trim each engine separately.

I have gone through the manual, and check online, with Spektrum site as well, and can not find anything. I have tried to program into the radio, but it is not coming together for me.

Would anyone have any ideas on this, and mind sharing to help me out?

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Last edited by kuiperk; 11-13-2010 at 10:10 PM.
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Old 11-14-2010, 10:59 AM   #2
I am: Philip A
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Re: programming two engines into DX8

2 Issues here:

1) Do you currently have the radio setup for dual ailerons? This will cause issues with your mixes.

2) If you don't have dual aileron enabled, then the flaps switch will cause some problems. You need to create a mix to 'null' out the flaps switch to prevent you from inadvertently controlling the 2nd motor:

AX1 => AX1
RATE D -100%, -100%
OFFSET -100%

Once you have the above setup, then create a throttle mix:

RATE 100%, -100%
OFFSET -100%

That should give you dual 'throttle' using both the Throttle and Aux1 channels. You can then use the 'Sub-trim' function for the Aux 1 servo to trim the second motor.

Note: You can do the same using the Aux2 channel instead. Be sure to null out the Aux2/GOV switch using the same method as the flaps switch.

To get even more tricky, you can program differential thrust for steering. Basically the rudder is mixed to both the throttle and Aux 1 channel using 2 separate mixes.

Note: I've done a dry run on the above settings with my DX8. I don't have a twin engined plane so I cannot test it 100%.
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Old 11-16-2010, 09:18 AM   #3
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Re: programming two engines into DX8

Back in the day before computer radios, we used helicopter radios on twin engined aircraft.

Today, I would still use the heli setting for my twins on my DX7

You plugged one throttle servo into the throttle and the other throttle servo into channel 6 (pitch). Now you had 2 servos running on the throttle stick and you could trim each engine separately to get the same RPM at idle, as well as the top end. Throttle hold worked great at the top of a hammerhead, you could get some crazy piro's with one engine at idle and the other at full throttle at the top of the hammerhead. The plane would spin like crazy in the vertical
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Old 11-19-2010, 02:28 AM   #4
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Re: programming two engines into DX8

That is a good idea, never thought of programming it in Heli mode.

Still new with the dual engine idea, think I will leave both going for the time being.

Thanks Philipa and Max for the input. I have the both going, but will make revisions to my setup based on your ideas.
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Old 11-19-2010, 01:24 PM   #5
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Re: programming two engines into DX8

I have a DX7 & ar7000 where my throttle channel is master to one of the other Gear, Aux1 or Aux2, I dont remember which, but I used one of the mixes.


and then I played with the up/down percentages to get the motors in sync through the range. Forgive me I don't have the TX in front of me and I can't remember what I exactly I had done. I can look it up and get back to this thread with details.
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Old 12-30-2010, 06:23 AM   #6
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Re: programming two engines into DX8

Rooky: It looks like you have done a nice job squeezing everything in. However, are you concerned at all about the strength of the firewall? There does not seem to be much left. I hope those blind nuts are surrounded with epoxy. Please don't take these comments the wrong way - having made every mistake known to mankind myself, I tend to be a little cautious. Cheers
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