RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2538 views POST REPLY
HomeAircraftHelicopter
e-
JR-Heli
Forza 700 › Forza 700 - Help Needed: Vibration at Hovering RPM?
10-26-2014 08:56 AM  3 years agoPost 1
christeneagle

rrNovice

MI, USA

My Posts: All  Forum  Topic

Forza 700 Owners,

Mine (brand new, maidened a couple weeks ago,5 hovering flights so far) is getting somewhat wobbly vibration around my hovering RPM (at 60% flat governed throttle curve w/Kontronic 200), and it seems to go away when I up the curve to 65% or higher.

I've done my due diligence on blade cg/weights, balancing, etc.(JR 710's, came almost perfectly balanced), and even replaced the brand new main/tail shafts with new ones. Still getting the same vibration at 60% throttle. It almost feels like that is the resonance frequency for this machine.

My set up includes, Scorpion520-Ultimate, Kontronik 200, JR 710 Main blades, Tags01, stock tail blades. Any ideas/clues/cures/suggestions?

Thanks much in advance,

-Tae

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 10:32 AM  3 years agoPost 2
rexxigpilot

rrProfessor

Florida

My Posts: All  Forum  Topic

wobbly vibration
Don't know what that is. Is it a wobble at a low frequency or vibration at high frequency?

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 12:41 PM  3 years agoPost 3
christeneagle

rrNovice

MI, USA

My Posts: All  Forum  Topic

I would describe it more of "high frequency" as it happens at hovering RPM, than the "wobble," which happens during almost every spool up.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 02:08 PM  3 years agoPost 4
rexxigpilot

rrProfessor

Florida

My Posts: All  Forum  Topic

If the main blades are balanced and the vibration goes away at faster headspeed you may just have a slight tracking error. Otherwise, it may be something in the tail. You didn't give much information on where it is vibrating or machine setup. Are you using the boom cover or a traditional pod/boom style.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 03:16 PM  3 years agoPost 5
christeneagle

rrNovice

MI, USA

My Posts: All  Forum  Topic

Thank you. I will have to check the tracking again (It is very close right now, but didn't pay the equal level of attention as I did for other items) I am using the boom cover. Vibration is all over the machine when it is there. Visually, I can noticeably see landing gear/tail fin vibrate.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 03:52 PM  3 years agoPost 6
LaDon

rrVeteran

Fort Dodge .Ia

My Posts: All  Forum  Topic

Check to make sure the pinion isn't to tight against the main gear. Also sometimes when the tail is put together the front torque tube gear can get pushed out and cause a vibration. Make sure that is pushed back in.

Team Jr

PM  EMAIL  GALLERY  Attn:RR  Quote
10-26-2014 05:24 PM  3 years agoPost 7
Ladymagic

rrKey Veteran

South Korea

My Posts: All  Forum  Topic

Its really hard to tell from your description if it's actually a vibration issue, but some of what you describe sounds like they may also be more of an oscillation problem. If in fact this is oscillation, then all fingers point to your TAGS gain settings. If you are getting more of a fore/aft vibe then it likely is oscillation.

Without a video, I would spam the usual suspects i.e your main shaft, gears and gear meshing, loosened hardware, and also your torque tube for trueness. Since you already checked out your blades you can rule those out, but you definately want to check your links and blade tracking.

If there is one thing I can say isn't my favorite about the Forza700 it's the hardware. I've gotten close to 15 full 3D flights on mine so far and I routinely find loosened screws and bolts. Last flight, both rudder servo mount screws worked their way loose enough to mess with my piros and nearly caused a crash. Do a very close inspection of all your hardware after every flight and I bet you'll find something that came loose. Also, check the main shaft collar as well, I've found if you do alot of pitch pounding it can work it's way up the shaft, causing play which may be a source of your problem as well.

The Forza700 is a well made machine overall and the solution is likely very simple. Systematically check stuff out and don't leave anything out. Good luck.

Mellisa

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 12:25 AM  3 years agoPost 8
mdu6

rrKey Veteran

Montreal

My Posts: All  Forum  Topic

If the 'vibration' goes away as you increase the head RPM, I would check for blades being a bit too tight and/or something not quite right in the head assembly.

Remove blades and rotor head linkages, check how free each main grip rotates first without applying any pulling force, then with some pulling force on the main grip. A very small (minute) amount of resistance during rotation is OK when not applying pulling force, it should go away completely as you pull. The opposite is NOT OK.

In doubt - disassemble the head, grease the thrust bearings, grease/oil (with rubber compatible) the dampeners and re-assemble everything back together in the right order.

This experience is not specific to the Forza - but comes from years of flying JR heads.

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 01:30 AM  3 years agoPost 9
christeneagle

rrNovice

MI, USA

My Posts: All  Forum  Topic

Thanks all. I knew I could count on this forum and all of you awesome folks! All the potential sources suggested here make a lot of sense to me. I will spend the next couple of weeks troubleshooting and report back. -Tae

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 02:35 AM  3 years agoPost 10
LaDon

rrVeteran

Fort Dodge .Ia

My Posts: All  Forum  Topic

I find that odd that the fasteners are coming loose Ladymagic. I am not saying it isn't happening but am wondering why. Ryan has about 150 flights on the one Forza 700 we got and we haven't even tightened a screw on it. In fact we haven't done anything to it but fly it. I need to get a video of it as you would see he shows it absolutely no mercy at all. We have it cranked up and are so happy with it because we can just beat it to death and it takes it. I use nothing but blue Loctite also no red. What I don't like about the fasteners is they rust real quick. That is what I have seen. The second Forza got drilled into the ground tho so it needed some parts but same with it. We have a KDE 700-505 motor in that one and it takes that kind of power well. I did go to Fastenal and get 100 of each screw in the Forza tho as I could get a bunch fairly cheap.

Team Jr

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 04:14 PM  3 years agoPost 11
Ladymagic

rrKey Veteran

South Korea

My Posts: All  Forum  Topic

@LaDon,

I'm not really sure why I'm getting so many screw backing out either, but honestly, it isn't that big a deal right now....just annoying. I always give a new heli a grace period as new parts and hardware get settled in so, I expected some stuff to loosen. So far, it's just the short screws that pass through the boom fairing and frame to the boom clamp that loosen up. Then, my main shaft collar slid up a little. With that, I noticed that the set screw was tighened, but not actually passing through the collar to the apply any pressure to the shaft, so the collar bolt was doing all the work. Last time it was the rudder servo mount screws that caused me to overshoot on a piro manuaver...that one make me pucker a little, but no harm done.

I usually only use blue loctite, but figured JR recommended the red stuff for a reason so I used it. What I'm finding now is that I am stripping screw heads to get some stuff apart. So maybe not being able to crank some stuff down as tightly may be why I get screws that back out. I have a million Allen sets and a even a few Japanese sets and I have a hard time finding the driver that fits perfectly. I am not blaming JR for anything here just stating an observation. I still think my Forza an awesome heli, but I will probably be buying third-party hardware to resolve the issue.

Mellisa

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 08:09 PM  3 years agoPost 12
LaDon

rrVeteran

Fort Dodge .Ia

My Posts: All  Forum  Topic

I forgot about the collar on the main shaft. We have had to fix that one also. Maybe ours ain't coming out on the others cause maybe it is that I am putting the big pythons to them. Hehehehe

Team Jr

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 09:47 PM  3 years agoPost 13
Ladymagic

rrKey Veteran

South Korea

My Posts: All  Forum  Topic

lol that must be it then LaDon. You should come and tighten mine down then too so I don't have to worry about it

Overall, the Forza700 is a fantastic heli. If JR came out with a 700N version, I think my head would explode. I would love to see a ForzaN and I don't think it would even be that hard to engineer. And you know you can guarantee at least one sale from me.

Mellisa

PM  EMAIL  GALLERY  Attn:RR  Quote
10-27-2014 09:57 PM  3 years agoPost 14
rappy112

rrApprentice

Guelph Ont.

My Posts: All  Forum  Topic

The vibration you are describing sounds like what I had around center stick and hovering with my Froza. As soon as I tried to land the whole Heli would shake side to side. What I found out was the the bolts that clamp the head onto the main shaft were not tight enough they need to be very tight, my fear in tightening them was the washout arms would deform from the tightening they never did and the arms are free moving. This solved my problem, hope it helps.

Kevin.

Proud member of Team Bob00

PM  EMAIL  GALLERY  Attn:RR  Quote
10-28-2014 03:42 AM  3 years agoPost 15
LaDon

rrVeteran

Fort Dodge .Ia

My Posts: All  Forum  Topic

We are with you lady magic we want a forza 700n also

Team Jr

PM  EMAIL  GALLERY  Attn:RR  Quote
11-05-2014 06:32 AM  3 years agoPost 16
christeneagle

rrNovice

MI, USA

My Posts: All  Forum  Topic

Vibration @ Hovering RPM, GONE! Thanks!
All,

Thanks to all your suggestions, I tried (almost) every suggestion above one by one to get to the root cause. It was that "something" in the head!

I re-assembled the head, and the only difference this time was I used Silicone based spray lube (vs. the "hobby oil" tube I used before) on the spindle shaft as well as that little Silicone grease thing for the dampeners prior to assembly. I was surprised how easy the reassembly was (because I remember the spindle shaft being pain in the xxx to get pushed into its position through 2 dampeners)

So, in the test flight following the head re-assembly, the Forza exhibited minor shake for the first 30 seconds or so (at which time, I was thinking, "this isn't it either!". Then, all of sudden, silky smooth hovering began,,, and that was it!

I must say, I certainly learned a lot through this trouble-shooting process, and thank all the experienced pilots here for the help/suggestions! Now I got a slight tail "nodding" issue to trouble-shoot!

Best Regards,

-Tae

PM  EMAIL  GALLERY  Attn:RR  Quote
11-05-2014 06:53 AM  3 years agoPost 17
tauscnc

rrKey Veteran

Joliet IL

My Posts: All  Forum  Topic

Also, check the main shaft collar as well, I've found if you do alot of pitch pounding it can work it's way up the shaft, causing play which may be a source of your problem as well.
The fix for this is easy and I am not sure why they don't do it. Put some washers under the main gear, or shims really and take up that space. I had to do the same on my Gaui X7. I put washers under the main gear and bearing block... and the entire thing has no where to go.

As for the screws, I was quite impressed how nice they were. Mine have not backed out at all either... not sure on that one Ladymajic.

Agree Forza 700N , Yes!

taus

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
12-18-2014 06:54 AM  3 years agoPost 18
robv

rrApprentice

SoCal

My Posts: All  Forum  Topic

@Mellisa

I stripped the heads that secure the tail boom when removing them. Not a fan of those 2mm button heads so I replaced of them with 2.5mm heads. They're easier to back out when you need to remove them. Oh btw, JR Japan states their red loctite is equivalent to the blue loctite we use here in the US.

Team JR | Gens Ace | YS Engines | Scorpion Motors | Pure Tech

PM  EMAIL  GALLERY  Attn:RR  Quote
12-18-2014 12:55 PM  3 years agoPost 19
Ladymagic

rrKey Veteran

South Korea

My Posts: All  Forum  Topic

ahh okay, I am planning to upgrade some of that stock hardware as well.

Oh I didn't realize JP red Loctite is really on blue. That's good to know. I figured I was stripping heads because everything was loctited with the real red stuff. But, I guess it just that the hardware is just too soft.

Have you heard anything in regards to new paint schemes? I see JR released a green body, but I am looking for a blue or yellow scheme. That would be awesome!

Mellisa

PM  EMAIL  GALLERY  Attn:RR  Quote
12-18-2014 01:14 PM  3 years agoPost 20
LaDon

rrVeteran

Fort Dodge .Ia

My Posts: All  Forum  Topic

The red being equivalent to blue is wrong. A friend had a guy put some of his Heli together and he used the red on everything. He messed up some of the assembly and I had to take it apart. Wow it didn't come apart. I thought he was going to have to buy another kit. I lucked out and finally got it all apart except one bolt and I had to cut it off and re drill a hole. I put ours all together with blue and I have had only the collar move and that wasn't because it was loose. Otherwise nothing has come loose. Shimming the main gear is a good idea tho. That would solve that part.

Team Jr

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2538 views POST REPLY
HomeAircraftHelicopter
e-
JR-Heli
Forza 700 › Forza 700 - Help Needed: Vibration at Hovering RPM?
 Print TOPIC  Make Suggestion 

 7  Topic Subscribe

Tuesday, August 21 - 8:59 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online