My Hurri 425 build

[Jerrymac]

Well, after many set-backs, I am finally putting my own Hurri 425 together. Got the frame together (complete with "stiffy"), the head assembled with CNC grips, the cyclic servos installed ( using the CF offset plates from ReadyHeli), the tail boom installed, and the motor mounted.

I cut part of the front frame off where the batteries go and mounted the "extra" plate supplied with the kit on there to run a single 6s lipo.
I broke both of the L-45 links while installing them so I made up some links from parts I had on hand. I think the L-45 links need to be sized before installing them as I even heated them up a little first, but still broke them.

Still fiddling around with electronics placement as the CG is off with a 6s 2500mah lipo strapped on. It is kinda nose heavy. If I can't get it balanced with the electronics, I might add a CNC tail case and tail grips to get the CG better.

Was hoping to maiden it this weekend, but, still waiting on the Pony Express ( UPS ) to get my blade adapters here from AlleRC to use blades with 3mm holes, on the grips with 4 mm bolt holes.
I ordered them last Sunday, but UPS tracking says they will be here next Monday. I guess one of the horses musta got sick or something.

Here are some of the specifics;

Plastic framed EP425
Gaui CNC mian blade grips, and anti rotation guide
Tonic-X Z20 1470kv motor
Gaui 50amp ESC
Hobbywing 5amp UBEC
Spectrum DS821's on cyclic
JR G770 3D gyro, with DS3500 tail servo
14/50/20/61 gears
Cheapie Pro 3D FRP 430mm main blades (Till I learn to fly it)

Anyhow, some pics to follow this weekend.

Jerry

[dunkonu23]

Good goin' Jerry!!!!

I'm anxious to see how you like it.... remember, I still have a 425 frame and most of the hardware around, too! Who knows?

Man, that's slow shipping. I always just use Priority Mail.. but I don't recall if that's even an option with AlleRC.

Scott

[Jerrymac]

Yea, I forgot to check the shipping options Scott, as I ordered an FG canopy and some other spare parts for the 425.
The order came to over $100 so it offered free shipping, but I did not notice that it shipped by Pony Express or I would have paid the extra to have it shipped USPS Priority if it was an option.

Live and learn.

[Jerrymac]

Well, not sure if the pics will show up or not, but I tried. Don't mind the wife's cats in the pics, they love to have their photo's taken, and always get in the way when I get the camera out. BTW, they love helicopters too. I have enough stools sitting next to my heli build bench for me and each one of them to sit and watch me working on them.

[Jerrymac]

Well, it seems that "Charley" got left out of the first pics that I posted, so here is one with him in it too. You guys may or may not like cats, but, these guys are my heli-building buddies.

[billmay]

Jerry - It's looking real good! What blades do you have on it? We've had cats for years so I'm very used to having them around as well. Good looking bunch of them that you have there! ;D

[EDIT] OK, saw your previous post with the blades. Let me know how you like those PRO 3D FG blades.....I've been using the PRO 3D 550mm CF version on my H550.

[Jerrymac]

Thanks Bill. I liked the bright colors on your 550 so I decided to put on the orange tail blades and paint the canopy orange too. It is just the cheap 2 piece plastic one that came with the kit, so I didn't get too fussy with the paint job. I did get a Gaui FG canopy from AlleRC for it though.

I haven't gotten a chance to really fly it yet. Just took it out in my tiny back yard Sunday to check the set-up and blade tracking. The head speed is scary fast , and the piro rate is wicked. I had the gyro gain at 25% to start with and the tail about wagged itself clear off. I have the gain down to 16% right now. Might need to do some tinkering with the tail set-up yet.

I will let you know how the blades work out. I bought 2 pairs of the 550mm to try out on the 550, but haven't installed them yet.

[9sec240]

Jerry, what is "stiffy" in your frame? Which FG canopy did you get from Allerc? I need something to pain white with a black window so I can throw those red paint slash stickers on it. Your cats are cool. I like the one that has the coloring and pattern of an Akita dog. Jon from the "strugglin" thread on RCU has some crazy big cats. He took pics of his 550 Huri with them one time. Pretty cool

[Jerrymac]

Ivan, the plastic frames have been known to twist slightly between the motor mount and main shaft under hard flying, and causes the first gear to strip. I drilled and tapped 2 holes in the bearing end of the motor mount and bolted a 1/4" thick piece of aluminum to it. Then I drilled and tapped the extra piece and bolted it through the front frame.
I will see if I can put up some pics as it would be easier to see it than try to explain it.

The canopy I got from AlleRC is part # 204166. It is an FG canopy and is already painted white with black window, and the finish is actually pretty nice on it for a $25 canopy.

Oh, and thanks for the cat comments. The Seal Point is my favorite.

[Jerrymac]

Ivan, I just checked AlleRC and that canopy is out-of-stock, but, Hobby Lobby in Brentwood TN. has it in stock.

www.hobby-lobby.com/h425_white_canopy_plastic_version_rc_helicopter_spare_part_272938_prd1.htm

[9sec240]

Wicked Jerry. Are you a machinist? I like the extra structure.

The canopy is exactly what I am looking for. Thanks much for the links.

[Jerrymac]

Thanks Ivan. Actually, I am a diesel mechanic and work at a Mack Truck dealership.
I think you will like that canopy as it is the stock 425 canopy.

Did you get the decals for it from Fred (dubehigh)? They do not come with the canopy.

[9sec240]

I did get the stickers from Fred. My dreams of having a larger looking 255 are going to come true!!

[Jerrymac]

Just 'get-er-done' Ivan. ;D

I did some tinkering with the tail on my 425 today, but won't get to fly it till the weekend to see how it flys, that is if the wind isn't too bad.
I set the tail up the same as my 550, but it don't seem to like it too well as I noticed in my quick back yard hover.

I had the travel adjust on the JR G770 gyro at about 60 to 70% and the ball on the tail servo arm out about 13mm, but the tail was too crazy. Had to turn the gain down to 16% just to keep the tail from wagging itself to death.

Today I moved the ball on the tail servo horn in to 10mm, and could set the travel adjust on the gyro to about 95% before reaching the slider limits.

Hopefully I can get it in the air this weekend to see how the tail responds. It wasn't holding well at 16% gain, but started to wag a little at 20%, so, will see if this helps.

I think I also found out why the head speed was kinda scary. Tonight, while cleaning off the heli build bench I found a 14T and a 16T pinion still in the packages, which means I must have put the 15T on it instead of the 14T. That means with a fully charged battery at 25.2 volts the head speed would be somewhere around 3300 to 3400. A little more than I had planned on, if my calculations are right. ;D

Jerry

[9sec240]

Sounds like you are getting close.

Sure wish I was getting my ready to fly this weekend. Guy claims he shipped the servo today.

[Jerrymac]

I finally got to take the 425 to the field today to test it out. Man, this thing is a ball to fly. The only problem that I had was an annoying 'bounce' in the tail.

The tail held great flying forward, and also doing some backward figure 8's, but, when doing a fast piro and letting go of the rudder, the tail would bounce back and forth a couple times. Not sure exactly why. I am using the same gyro on the 550 and it don't do that, although the tail servo is different. I tried reducing the gyro gain a little, but it still bounced after a fast piro.
The tail doesn't wag at all during flight, just a bad bounce after a piro.

Any ideas guys?

Jerry

[dunkonu23]

What kind of Gyro, Jerry?

Scott

[9sec240]

Speed of the servo has a lot to do with bounce. On the GY401, you need to add delay for slow servos to remove bounce. The other thing I have found that causes bounce is sloppy or flexible tail control rods.

[Jerrymac]

The gyro is a JR G770 3D, and the tail servo is a JR DS3500. They came boxed together as a combo set, so I would think that they should work properly together, I dunno.

I will check the linkage and tail to see if I might have some problem there.

[dunkonu23]

Jerry, I read the manual for your gyro just now and about the only thing it said about stopping was that it's a gain adjustment. I'm thinking they mean to set the gain really, really close to the wag point...like maybe one click away and see what that does, but they don't come out and say it.

Also, just by chance are you letting go of the rudder stick to stop the piro? On my DX7 if I do that, it's kind of funny to watch, but it's more like a springy bounce.

Scott