Can it be done with a DX7

[DMfrench]

I got a DX7, and have been able to get most of my models easily programmed into it. All that is, except one, my frankenheli...

Basically, I want to control a Walkera #4 fixed pitch heli using a spare eflite 4-in-1 I have from a Blade CX2 coaxial. I was able to get it programmed so the servos are working properly, but I'm having trouble figuring out how to control or program the main motor and tail rotor motor. I have them plugged into the two motor plugs on the 4-in-1, but that really doesn't work right because it comes out of a coaxial heli. When I give it some rudder input, it speeds up one motor and slows the other just like in the CX2. That's not good on a single main motor setup.

Does anyone know of any programming tips, or different setups, so that I can get control of the rudder without slowing the main motor? I don't want to spend much money on new electrics. This is just a beater that I'm trying to put together with spare parts. Thanks,
Dave F.

[teeson]

you put a DX7 on a walkera #4? kewl i didnt think that those 4-in-1 things were hackable..

[skunkworx]

I thought about doing the same thing on the 52. The bad news is that it'll be tough to pull off because the mixer is not the right kind. As you said it's out of the CX2 so the only thing I can think of would be to run full separates or try to get it setup in your program mixes. (sorry I can't help with that one)

GWS makes a cheap/light 5A brushed ESC for $11 and you'd probably be able to just drop in a CC10 ESC and a 12mm motor. The Gyro would be the only other costly option. I have an Ikarus micro HH gyro but haven't had a chance to get the whole thing put together, so I'm not sure how well it holds (but it's light! 3.5grams!)

If you added all that, you'd be able to just dump the 4-in-1.

The last option would be to get the 7-channel Walkera radio and 4-in-1 (if they are different) out of a 52 or 60 or 36 (think) and use that instead. I know a guy who flys his 52 better than I can fly my T-rex with the stock radio stuff and he's got well over 300 flights on it!!!

Good luck on your project!

[DMfrench]

So, I'm still putzing around with the project. Nothing I've tried on the DX7 overrides the mixing that occurs in the onboard eflite 4 in 1.

My next step is to open up the 4 in 1 and see whether it would be possible to disable the mixer, which should give me separate control of each motor, right? Or am I just not understanding the function of the eflite mixer for a coaxial bird?

Others suggested picking up a spare esc, but I don't know where to plug it into the 4 in 1.

Essentially, I need to figure out how to keep the main motor from slowing down when I give the heli rudder input. I do appreciate the feedback so far.

Dave F.

[skunkworx]

You could use the 3-in-1 instead. That's setup to run main/tail motors. I did the same with a Blade CP Pro, works like a charm! (Cheapest way you are going to get around it). The gyro isn't so great, so that might need an upgrade, but it will fly. You could sell the 4n1 and get the 3n1 for the difference. Try asking around in the for sale section for a cheap one that someone has sitting around)

Maybe that'll give you some new hope?

[Stump3r]

My Walkera #4 is flying like a champ with my DX7. I did it using a Blade CP Pro 3in1. I had to add a ton of negative expo to get it flyable and you will probably want to use some revo mix to make up for the lag with the tail rotor. I also run the CP Pro main and tail motors in my #4. It took me a good hour of playing with settings in the tx to get her just right but once you get it, what an awesome little bird.

[skunkworx]

Good deal Stumpr!
Are you using an ouside gyro, or just going with the one in the 3n1? Got any pics of your setup by any chance? I'd love to see it. I wish they could make the 3n1 smaller so I could get it into my 52! I'm working on that right now, but am about to throw the 'ol stock 4n1 back in it and learn to program it. I know someone who can fly circles around even my Trex with his 52 on stock electronics!

[Stump3r]

Have pics posted over on RCU here http://www.rcuniverse.com/forum/fb.asp?m=7048542
If you want when I get home tonight I can PM you my DX7 settings. I have her setup pretty sensitive on cyclic but it would be a good place to start.
Just using the stock 3in1 gyro. It isn't super but it works. Very flyable.

[skunkworx]

Sweet! That'd be awesome. I'll check out your post. I kinda figured there'd be someone else out there who had it figured out. Thanks for the help!

[skunkworx]

So the #4 is the same thing as a Blade CP I take it? Looks similar, but I've never seen one besides your pics.

[Stump3r]

Well not really. The Eflite Blade CP/CP+/CP Pro are all collective pitch machines, the Walkera #4/Honey Bee FP/Falcon F40 are all the same size but are fixed pitch machines. They are all very similar in size, use the same size main motor and tail motors. I think the tail booms, and tail boxes are all the same as well. That's about it between the two series.

I used the CP Pro 3in1 strictly because it has all the goodies you need minus the rx and it's relatively cheap. The 3in1 was 46.00 and the AR6100 was 50. If you went separates it would double the price. Easy way to get the #4 on a DX7.