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NX4 Discussion and support of the Gaui NX4 Nitro Helicopter


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Old 07-09-2016, 10:10 AM   #1 (permalink)
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Default Just picked up a used NX4!

Got a used NX4 on what seems to be a pretty good deal, guy threw in a whole bunch of spares and a (broken - I can try fix) starter, manual fuel pump etc.

Managed to organize some rapicon 30% nitro (1,25 gal of it) from a friend who recently sold all his nitro helis, for a decent price.

Can't wait to get started on the setup!

Going to run:
- gaui servos on cyclic and tail (HV)
- turnigy HV servo on throttle
- gaui mini vbar flybarless (not included in kit gonna organize still)
- 2x DSMX sats
- OS37 motor and gaui muffler
- gaui gov
- some sort of push glow

Still A LOT to learn about nitro setup etc. Going to try do my research and then place order for parts that I need either Sunday or early next week. Not in a mad rush to get her flying, rather take the time I need and get everything setup right!

As I understand I need to run sats not a standard receiver so that I can free up a channel on the mini vbar to output signal to the governor. I only have a 6ch (dx6i) radio but I have a vbar bluetooth module (and you can do setup on PC) so I'm thinking to use the AUX channel normally used for gyro gain or bank switching to output and use for governor rpm setting and use PC/bluetooth to do tail/head/etc gain tweaking.
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Old 07-09-2016, 10:16 AM   #2 (permalink)
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just a quick pic for you guys!
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Old 07-09-2016, 10:24 AM   #3 (permalink)
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Congratulations ! Everyone should have at least one nitro in their fleet. I just run 15% as I don't push mine much at all.
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Old 07-09-2016, 10:35 AM   #4 (permalink)
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Nice! The NX4 is a great heli. Mine's a keeper!
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Old 07-09-2016, 10:59 AM   #5 (permalink)
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Yeah the guy I bought it from mentioned he ran 15% and seemed happy with it, but I got the 30% for a gooood deal!

I think it'll be a fun heli for fields where there's no power as well. It sucks to drive 30min+ and then fly out the few packs you brought from home and then drive back. With the nitro at least I can bring a few RX packs (or charge them off the car battery cos they're small mAh) and a bunch of nitro fuel and just go mad!
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Old 07-09-2016, 11:11 AM   #6 (permalink)
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Don't forget to order your support stuff. When I first got mine it was like how the #$@& do I start this. I finally found a 6mm ball starting shaft on Amazon. A good 20V drill is also a must. Spare glow plugs, fuel pump, etc etc.
Consider adding a remote glow plug extender if it's hard to reach. I like being able to fuel, start, and go again without having to take off the canopy.
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Old 07-09-2016, 11:27 AM   #7 (permalink)
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Regarding that starter. Pull the end cap and make sure the brushes move freely in their mounts. They sometimes get gummed up. Not much to a starter. Might save 40 bucks on a new one.
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Old 07-09-2016, 05:48 PM   #8 (permalink)
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Nice! Welcome to the NX4 club
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Old 07-10-2016, 01:50 PM   #9 (permalink)
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Originally Posted by Raleighcopter View Post
Regarding that starter. Pull the end cap and make sure the brushes move freely in their mounts. They sometimes get gummed up. Not much to a starter. Might save 40 bucks on a new one.
Nice heads up on the brushes thanks. They were indeed gummed up completely couldn't move even a fraction of a mm. Got them loosened up and then realized the switch is not working either. It's two pieces of metal separated by a foam pad on one side and a plastic spacer on the other side, when you press it just squishes the metal together to make contact. Problem was that the outer part of the switch, where you press, wasn't squishing them together enough to make contact. Put a small plastic spacer in and it seems to work great. Tested the starter with a power supply (pc power supply) it spun up (yay!) but then it tripped the power supply into protection mode, either short circuit or over current I'm not sure. Either way progress is being made.
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Old 07-10-2016, 03:29 PM   #10 (permalink)
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Good deal. You can get a replacement switch for about 5 bucks plus shipping if you decide you need one. Also, i use a 4s, 1500 mah lipo with mine.
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Old 07-19-2016, 05:49 AM   #11 (permalink)
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Made a lot of progress on the electronic setup on the weekend, got the FBL all set up, got the gov throttle calibrated and the throttle servo setup etc done.

Realized I needed a y-harness to power my push glow starter so I ordered that along with some other spares like glow plug and fuel tubing etc.

Very possible that I might be ready to fly it this coming weekend!
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Old 07-20-2016, 01:30 AM   #12 (permalink)
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Congrats on the NX4, fun bird.

I've only ever run 30% myself, but I think the lower nitro fuel runs a little leaner needle settings. You mentioned the previous owner ran 15%? You may want to check your needles and maybe come out to the factory break in settings and tune from there.
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Old 07-20-2016, 08:27 AM   #13 (permalink)
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Congrats on the NX4, fun bird.

I've only ever run 30% myself, but I think the lower nitro fuel runs a little leaner needle settings. You mentioned the previous owner ran 15%? You may want to check your needles and maybe come out to the factory break in settings and tune from there.
OK cool thanks, that's good info, I'm still new to this nitro stuff haha!

Yeah, previous owner ran 15% so I'll take it back to break in needle settings and tune from there for the 30% that I'm planning to run.
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Old 07-20-2016, 11:12 AM   #14 (permalink)
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OK cool thanks, that's good info, I'm still new to this nitro stuff haha!

Yeah, previous owner ran 15% so I'll take it back to break in needle settings and tune from there for the 30% that I'm planning to run.
The 37 is a really easy motor to tune. I use the "5 second rule" with it myself. Here is how I tune my broken in 37 with 30%. Others may differ, but this is fairly safe and will yield good results.

1.) Lean idle/mid until I get a fairly smooth ramp up without it stumbling, and spitting fuel everywhere. (Make sure it's warmed up for this). You still want it a little rich here, so you want to hear it moaning just a wee tad as it comes up. You'll hear what I'm talking about.

2.) Take her up and do full collective full throttle maneuvers, don't let it rest at all. I usually do hurricanes for a solid minute. Land very quickly and feel the backplate quickly. Keep leaning until you get to about a 6 or 7 second count before it starts to burn your finger.

3.) Full throttle to partial throttle transitions. Usually I do hurricanes to clean out the fuel then transition quickly to a gentle forward flight and watch the smoke. Lean mid/idle until smoke is fairly consistent with full throttle maneuvers. You can do tic tocs here too, but mid will probably be too rich at first. Check back plate on occasion while doing this.

4.) Go out 2 clicks on the high and repeat #2, make sure your at a 6 or 7 count. Once that's done, do tic toc's non stop for like a minute. Make sure your still at a 6 or 7 count. Go back and forth with this till their balanced. Also make sure your continuing to gain power in your tic tocs as you lean and not loosing power. If your loosing power you've gone too lean, come out about 1/8 turn and that should be good. Also make sure your not hanging on the pipe when you spool down (hanging on the pipe = ting ting ting sound and taking a long time for the engine to come back to smooth idle).

5.) Once your at a 6 or 7 count throughout the range your 1 click on the high from a 5 count. Going any leaner than a 5 count won't yield much in the way of more power and is getting closer to danger territory. At most (on a hot day) I'll go one click in from a 5 count which usually get's me to about a 3 count. This is the point where you can start hearing the heli starting to lean but not lean, and also where you'll start to smell the heat on the motor.

I would equate the power of a 37 on a nx4 around about a 4cell 450 swinging 325's around 3200rpm. Not really beastly, but not really a complete dog. If it starts feeling like a 3s 450, replace your ring and bearings, and inspect all your seals. A fresh ring and bearing on the 37 makes a huge difference. To replace the bearings completely strip the motor heat in the oven @ 400 for 15 minutes. Bearings should pop right out. I use the copper cleaning pads from the grocery store to clean residue off the crank, and freshen up the liner. Be careful not to spin the liner around the piston/ring as your inserting, line it up and gentle back and forth wiggles as your pushing it down keeping it lined up. May not be a bad idea to pickup an extra ring, just in case, don't ask me how i know this .

Good luck! and Enjoy!
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Old 07-21-2016, 03:39 PM   #15 (permalink)
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Congrats and welcome! A handy addition that I put on mine was an easily accessible power switch for the electronics. That way I can power off between flights and refuel etc without ever having to remove the canopy. only time it comes off is to recharge the rx pack.

Other handy add-ons are an os55, gaui x5 boom, and 520mm blades but those come later
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Old 08-04-2016, 01:34 AM   #16 (permalink)
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Default Got her started!

Had the day off yesterday so I spent all morning flying my oxy3, but then I figured I might as well make use of the time to at least do something with the NX4!

Checked everything, double checked it, put a bit of fuel in her and started her up! She starts, she runs, it's awesome! Kept forgetting to push the push glo button haha!

Definitely planning to get her flying this weekend (plus it's a 4 day weekend so that's great!)

Thanks for the tuning tips jbaum81, will try put them into practice this weekend, really appreciated.
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Old 08-07-2016, 06:15 AM   #17 (permalink)
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Took her to the field yesterday and could not get her to start, she wouldn't even turn over, the starter would just turn a tiny bit and then stop. Decided to pack her in for the day and flew the oxy3 a ton. Got back home and pulled the glow plug, spun the motor by hand a few times from the starter shaft in my hand and it all seemed fine, so I put the glow plug back in and fuelled her up and of course she started in my yard no problems! Figured I might have messed up when I fuelled her up at the field? Not 100% sure.

Took her to the field again today and she started right up! BUT I seem to be getting a heck of a lot of vibration, before lift off throttle the swash is jumping around like crazy, definitely not flyable like that. Will try strap the FBL down with a strap and see if that has any effect otherwise I'm just gonna think of other ideas to check...

The good news is that my oxy3 flew great and I was able to really work on improving my 4-point tic tocs where before I mostly just bailed out of them haha.
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Old 08-07-2016, 11:49 AM   #18 (permalink)
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If your starter won't turn the engine over that sounds like the engine is hydro-locked. Easiest way to fix this is to turn the heli onto the pipe side and bump the starter a few times. Usually will clear out the engine. Or just pull the plug and let the fuel drain out the glow plug hole.
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Old 08-08-2016, 07:20 AM   #19 (permalink)
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If your starter won't turn the engine over that sounds like the engine is hydro-locked. Easiest way to fix this is to turn the heli onto the pipe side and bump the starter a few times. Usually will clear out the engine. Or just pull the plug and let the fuel drain out the glow plug hole.
Yeah, definitely sounds like hydro-lock! once I saw your post with that terminology I googled and it definitely sounds like what happened to my motor.

Good to know that you can lay the heli on its side and clear it like that, awesome!

Put a velcro strap tight around my vbar this morning and ran it up to just shy of 50% throttle, maybe like 43% or so in the yard and I didn't see any swash plate twitching from vibration like before, so it's possible that the strap is helping. Will take it to the field and test there again possibly tomorrow if I have a chance. Can't really test hover it at home, there isn't enough space!

It's running pretty rich on the low mixture adjustment, you can hold your hand behind the muffler and get spits of fuel after a few seconds. But it picks up throttle very well and doesn't stutter or hesitate or anything. Produces a nice bit of smoke but nothing super excessive. Takes closer to 5 seconds before it picks up revs if I pinch the fuel line close to the engine but peaks at around 7 seconds and finally dies around 10 second mark.
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Old 08-08-2016, 10:50 AM   #20 (permalink)
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Can you tell what kind of tape the FBL unit is mounted on? I am using a mini Vbar on my nx4 and used 3M 4011 tape. I have never experienced any vibe related issues with it.

https://www.amazon.com/Scotch-Exteri...ywords=3m+4011

Hopefully you can find this where you live. On the hydro-locking thing just make sure you only bump the starter don't hold it on otherwise you can damage parts.
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