Gaui Hurricane 425 Build Log - RC Groups
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Apr 17, 2011, 12:46 AM
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Build Log

Gaui Hurricane 425 Build Log

So I decided to do a build log on the Gaui Hurricane 425. I'm an intermediate flyer and am going to keep this simple for the non-mechanically inclined people (like me!) and I also don't mind any recommendations as I haven't built many helicopters. So here it goes!

I decided on getting the Gaui Hurricane 425 because it is a quality brand at a clone price. I went with a 500 sized heli because I prefer flying them on the sim and wanted something I could fly in a smaller field, but was till big enough to see when it was flying.

Some of the reason I went with the Gaui are a simple CP head, lots of upgrades, and oh yea the price!

I bought it from HeliFlightCenter for $79.99 shipped ( I also got the Carbon 3D pro blades for an extra $20 bucks as well. I ordered it on a Saturday and it arrived on Tuesday, plus they packed it really well (I can't stand when I get a box and it is wrapped in brown paper and not put in a packing box).

It's funny to see these big helis come in such a small box:

For comparison, here is the Gaui box next to an MCPX box:

Now when you open it, you get to see two halves of your canopy (it's actually not bad assembled) and some documentation:

And under neath the top tray you get to see all the parts in their nice individual bags:

The funny thing is that the box smelled like a skunk on the inside. It made me wonder if Gaui is the Chinese word for Skunk. I was thinking this was due to the material of the blade holder, but I don't know.
Last edited by GetterDragun; Apr 17, 2011 at 01:16 AM.
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Apr 17, 2011, 01:03 AM
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First thing the instructions have you do is to assemble the main frame. Here are the bag of parts you will be using (note some of the parts in the bags will be used in later steps, I started wondering if I missed something, but by the end of the build everything will be used).

You start with the frame side (right side) that has the holes for the nuts:

You need to put the nuts as flat as possible and then push them in with something. I used the end of the tool.

Make sure that the nut is as far in as it can go, it should not be sticking out at all, most likely they all be just below the surface of the frame.

Once done, you should have this:

Apr 17, 2011, 01:15 AM
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Now we need to put the bearings in and assemble the frame.

Simply put the bearings in (using the frame that you put the nuts in, this way it makes it easier to screw the frame together), they should fit snug in their spot.

Now lay the left frame on top. Note that the bearings for the tail belt gear fall out easy during this, but that's normal, just make sure they are seated correctly before you fully tighten the frame. Also at this point you could put the gears in from the next step shown on the probably would make it easier to install. You use the long screws for most of the fastening except for the two spots in the middle of the frame that are recessed in holding a bearing and the nose of the frame takes one of the four self tapping screws that came out of the bag. I want to note that it seemed like my frames (or one of them, couldn't tell) were slightly bowed out in the middle. So I started with the screws in the middle of the frame, but wouldn't tighten them all the way. I would work my way around the middle putting the screws and tightening each of them in order little by little until the frame pulled closer and closer together and then connected.

Once you finish this, you will have your frame (Note: I didn not install the aluminum motor mount at this time since I do not have my motor or pinion yet)!

Next is the landing gear, here are the pieces you will be using:

And once screwed together:

Now we need to assemble the skids:

Don't forget to put the screw in to hold them on:

And you've completed the step:
Last edited by GetterDragun; Apr 17, 2011 at 01:28 PM.
Apr 17, 2011, 07:23 AM
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Dragun looking good you will have it flying soon
Apr 17, 2011, 09:50 AM
ooooh yeah
Frenche's Avatar
Looking great!! The more I look at these Gaui's the more I want one, but do I really need 3 500 size heli's?? haha
Apr 17, 2011, 11:49 AM
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Thanks for the compliments so far! This was a real easy build and I am definitely not the most experienced builder!

Next thing we need to do is to attach the servo arms. The servos are not direct to swash, they go to these intermeddiate servo ars which then drive the swash.

Here are the parts that you will need for this step:

One thing that intrigued me about the helicopter is no swash plate guide! I don't know why, but I can't stand swash plate's always the part that breaks and that are always out of stock on! This piece is driven by the the outer control arm and acts the elevator control arm as well as the swash plate guide. When installing it, just loosen the frame up top a little and it goes right in. Note that the holes on either mounting point are different and one takes a screw and teh other takes the control arm.

You also need to add this plate to the front, which I have no clue what it does yet as I haven't mounted a battery or electronics. However, if you plan on going 6S (I'm unsure of the batteries I am using now) they have an adapter that mounts under it so you can go 6S. I believe the adapter is perment because they say to use CA on it. You can always go 3S and add the adapter later if you want to go 6S, but it is something to think about.

Now back to the servo arms. These are pretty easy to install, so not much to say. Here's a completed pic of this step:

Apr 17, 2011, 11:56 AM
Barnwell, SC
Great photos GetterDragun! I haven't started my build yet. I'm going with the 500 blade stretch.
Frenche, you do need 3 500's, go ahead and order it! I have HK and EXI 500's plus a Swift NX. I think it will be cool to have a size in between.
Apr 17, 2011, 12:02 PM
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Now onto the gears. The gears do come assembled as opposed to the manual showing that they are dissassembled. Now in terms of loctiting...on the gears I am going to spin the heli up first as they appear loctited from the factory...but I want to see how they hold after my first spin up (I never test hover...I fasten the heli to the ground, stand waaaaayyyyyyyy back (or in my garage looking out the window) and spin it up...but that is for a later discussion.

The gearing install is easy, but for you "gear heads" there is a decent amount to think about with the gear ratios. While I am not the best at explaining this, you can download the Gaui manual from their website here: (go down to EP425 plastic) to help you decide what pinion you want based on the motor you have.

They say to put some grease on the washers, this is so you can slide the lower smaller gear in place and the washers don't keep sliding out. I just used balance to get them on! Like I said before though, you could probably have put all the gearing in before putting the frame halves together and might save like a minute, but i went along with the instructions.

I forgot to take a pic of the rear tail gearing, but here's a pic installed (went in the same as the others):

Apr 17, 2011, 12:05 PM
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Originally Posted by hfenn
Great photos GetterDragun! I haven't started my build yet. I'm going with the 500 blade stretch.
Frenche, you do need 3 500's, go ahead and order it! I have HK and EXI 500's plus a Swift NX. I think it will be cool to have a size in between.
Cool! Another Gaui going up. For the price you can't beat them (well, from what I've seen so far). I am tossed up about going for the stretch or doing a heliartist scale fuselage and staying this size. I'm leaning towards that nice Airwolf body!
Apr 17, 2011, 12:22 PM
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Now on to the main rotorhead. The mead is mostly plastic but with some metal parts thrown in. The quality of the plastic is awesome. And I suspect it will hold up better than some of the metal head pieces when you have an unexpected landing. The only piece that is all metal is the swash...and the funny thing is is that the replacement part price for the swash is almost as much as the whole helicopter!

One of my favorite parts of this helicopter was the simplicity of the head. Most people with TREX or TREX clones know you have 6 linkage adjustments on the head. With the Gaui, there are just two adjustments that need to be made. The remaining links are solid plastic, so no need to adjust! The rest of the adjustemnt are done at the servo arms are and that is much easier to do then to keep taking on and off multiple rotorhead links.

One thing I would like to add is that the swash appeared to have been loctited. But I don't trust other peoples application of loctite. I dissasembled all of the ball link screws and loctited them with blue loctite back in place. One screw on the swash felt like it might have slipped. Personally I think the screws in this kit are rock solid, but this was just the one screw I had a problem with. I let the loctite cure on that one screw before testing it again and it felt solid, but after my initial run in I will check again and see if it loosened if it did, I will use some CA instead of loctite and that should hold it. The funny thing is a new swash costs almost as much as the whole kit!

Here is a picture of the main rotorhead and it does come assembled:

Here is the rest of the rotohead assembly:

Now here is a pic of it installed with the links attached:

Now you just have to put the gear on the bottom. And you finally get to use that one washer that's een lying around since the beginning!

I'm going to hold off putting the flybar in for now as it will probably just get in the way.
Last edited by GetterDragun; Apr 17, 2011 at 01:11 PM.
Apr 17, 2011, 01:06 PM
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On to the tail!

Hear is the pieces needed to assemble the tail:

Now let's combine the tail blade holder/slider:

And put it on the tail! Note that the tail boom has a hole on one side, this is where the tail box assembly mounts too. You will see a little button inside one of the tail box assembly sides (right side) this is what keeps the tail box assembly from rotating when hitting the ground. Assembly is pretty straight forward, just make sure you put the belt in before you assemble the tail box.

Then once you are done with that...add the tail blades:

Last edited by GetterDragun; Apr 17, 2011 at 02:12 PM.
Apr 17, 2011, 01:26 PM
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Now on to the tail boom. The thing looks like a baseball bat! I also like how it has a bit of a pearlecent finish (it almost looks like they hit it with a little purple which makes it looks higher quality.

The belt on this think looks like it came off of a Ford pick up. However since they had it coiled for shipping, there is a little king at the end. I used a binder clip for about two ours to pinch the belt back into place. Then I hung the belt on the tailboom so that the kinked spot on the belt had some weight on it (the tail box assembly acted as the weight at the other end). I let this sit for a few hours and the belt straightened itself out.

Now you have to put the tail boom onto the helicopter. Pretty easy...just loosen the four screws around where the tail boom slides it in and loop the belt around the tail gear. Then pull back on the tail boom until you have prope tension and retighten the screws.

However, this is the one piece of assembly I was thinking could be a little better. I know you need something to give if you land hard, especially with the tail. But the only way to get the tail straight is with a level attached to the tail fin and a steady hand. Then you just tighten the screws. It would have been nice to have some sort of guide cut in to the tail boom that could have been used to hold the tail boom steady once put into the frame. We'll see how straight the tail boom stays after a few flights.

Here's the tail boom installed:

Now put on the tail boom supports:

And now it's looking like a helicopter!

Apr 17, 2011, 02:23 PM
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Now we move on to the flybar. Once I get the servos in, I'll properly level everything, but I have a feeling leveling the flybar is going to be tricky.

Here you can see the pieces need for the flybar. Now you get to use those little bearings that were in the same plastic with the rotorhead...don't forget to put the washers on them either.

The flybar looks like it should be around 13.3cm on each side to be even.

Here is the assembly of the flybar:

Now with the paddles on:

And after adding the links for a completed head:

Apr 17, 2011, 02:27 PM
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Now on to the canopy.

To be honest, when I was cutting the canopy out of it's plastic, I was thinking of just junking it and buying one of the better caopies for this helicopter. It's made of that plastic that when you cut, the plastic cuts more than you want and makes it uneven. When I glued it, I used Gorilla Glue Super Glue. Once dried, it kind of looked crappy and wasn't perfectly even. To put the rubber grommets in, you need to drill out the frame where the indentations are with a 1/4" drill bit.

However, a sharpie and some stickers went a long way in dressing it up, so I will keep it.

First, you need to put the canopy holder onto the frame.

And now...the completed canopy!

Apr 17, 2011, 02:29 PM
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And now, the finished helicopter!

Next to the MCP-X for size comparison:

And with the blades extended:

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