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Century Helicopter . MTA Hobbies . Model Rectifier Corp

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Compass Knight 50 > Knight Tail failure....
 
 
Disc
Heliman
Location: Lincoln,UK

I had a badish day


I was happily flying around gentle stuff no 3D or even a stall turn or loop.

I lost all Tail control! I had nothing so i got low enough to hit throttle hold and got it down....

But upon inspection the tail pushrod is connected all the way from servo to tail. BUT the servo mount was broken!

Now the gyro (CSM 560 and servo 9254) are working fine and have not given me cause to doubt them yet.

But damage was flybar boom/1x main blade and some other bits i'll change feathering and main shafts and order spares I expect. under carriage survived though!

Metal Knight though so still unsure what happened but definatly something to do with the tail. shame I was really enjoying it.

Kesteven Model Flyers, UK
03-02-2007 Over year old.
HOMEPAGE  
 
 
Donkey
Senior Heliman
Location: Punta Gorda, FL

Doubt the servo....If you even see a little twitch while flying...BTW don't bother to send it back HS will just tell you you got fuel on it.

Donkey you have the right to remain silent what you lack is the capability
03-02-2007 Over year old.
 
 
RAK402
Veteran
Location: Alhambra, CA

Disc,

Sorry to hear about the failure.

What part of the mount broke? Could the mount have failed in flight?

I am flying the metal Knight also, and will inspect my tail servo mount, but would like to know what to look for.


Thank you.
03-03-2007 Over year old.
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

I thought you were about to say that it was the tail hub that failed, that happened on a mate of mine's Knight. He just had a lovely flight at a fly-in, brought it back down to land, got to about a foot off of the deck and the tail just exploded!!
Compass have admited that there could be a durability problem with the original silver colour hub so they've made another one now coloured black.
But as for the mount I have heard of failures of that part in the past, not many mind you.
I'm tempted to change to the old style mount which bolts to the frames not too sure if I can get hold of one though.
BTW Disc, what tail blades are you using?

Am I still in control?......................OH!
03-03-2007 Over year old.
 
 
Disc
Heliman
Location: Lincoln,UK

Okay been over the Knight...

the Servo a 9254 is not at fault at all it has plenty of power. It takes a lot to even try and move the servo arm so its fine both directions no bad wires any where.

Now I can confirm the Servo Mount failed in flight. Even the Crash damage means the servo mount took no impact at all no part that side was damaged.

Slightly pissed about a metal mount failing and causing the damage but at least it wasn't my flying

Tail Blades NHP's not the compass one's as the quality isn't there

What should I use to mount the servo then? Wounder if a Predator tail servo mount would fit on it.....

Kesteven Model Flyers, UK
03-03-2007 Over year old.
HOMEPAGE  
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

The quickUK Raptor tail servo mount should do the trick for you, I've had one before and they're very well made, I think you get a choice of colours as well.

Am I still in control?......................OH!
03-03-2007 Over year old.
 
 
Disc
Heliman
Location: Lincoln,UK

As long as it just goes on thats good.

I hate it when you have to mess about getting the dam things to fit right.

I like the Knight but sometimes the quality just gets to me!

If I had known this was a weak part I'd of changed it straight away.

Kesteven Model Flyers, UK
03-03-2007 Over year old.
HOMEPAGE  
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

Well the good news is the Knight certainly aint renowned for causing people grief, so far it's proven to be a very reliable machine.
I would like to see some beefier pushrods offered by Compass, the stock ones are IMO a bit flimsy, with that said they do the job though. btw I mean ALL of the helis pushrods!

Am I still in control?......................OH!
03-03-2007 Over year old.
 
 
tnbulldog
Senior Heliman
Location: Cookeville, TN

I would look for an Evo50 tail servo mount. I'm pretty sure the boom is the same diameter.
03-03-2007 Over year old.
 
 
Disc
Heliman
Location: Lincoln,UK

I'd agree the Knight isn't a bad machine but as you say push rods need to be beefier. But there not the only part. Allen bolts are poor quality as well IMHO and some of the other screws as well.

Knight is nice apart from some of the parts quality I cannot fault it.

I can see my predator nitro going for its 1st flight before I fly the Knight again though. Just so long as that flys okay!

Kesteven Model Flyers, UK
03-03-2007 Over year old.
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petmotel
Veteran
Location: DeKalb, IL.

Pics of mount?

Wondering if you could post some pics of what broke. Might just save someone else some grief in the future.

I'm currently building a Knight 3D and went kind of Quick UK crazy with it. Grips, struts, fin/strut mount, tail servo mount, tail control rod, base loaded antannae, header tank, servo mount plates, etc, etc, ad infinitum. Incredibly high quality stuff if you want something bulletproof to mount that tail servo. Very cool looking too, simple and elegant. It tucks the servo next to, and on the right hand side of the boom which makes it very inconspicuous. I also understand why they call it Quick UK. Eats up money quick.

Before anyone points out that the stock stuff works perfectly well, I'm fully aware of that. The sport I fly is completely stock, save for the tail blades that are way too soft. I use the 92mm blue plastic Freya blades which are themseves quite inexpensive. I have way too much time on my hands that I can't fly due to the crap weather here in the midwest, thus the mods that are wholely unnecessary.

Anyone wanting one of those frame mounts, I have one I'm not ever going to use. Send me a PM and I will let you have it for the price of a self addressed envelope.

Jay
03-03-2007 Over year old.
HOMEPAGE  
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

Quote 
Allen bolts are poor quality as well IMHO

Well I sort of agree with this, they certainly aint high grade stainless steel but on the other hand I've not found them to be too bad either, I do use proper hardened hex drivers on them mind you, proper tools makes a hell of a difference.

But at the end of the day what we have is a perfectly capable, reliable, stacked metal frame, full metal head and tail and GRP canopy helicopter for just £350. For not a lot of dosh you can upgrade the very few parts that really need it and be left with a machine that can hold its own with the very best of 50's out there (well very nearly!!)

Am I still in control?......................OH!
03-03-2007 Over year old.
 
 
deiniolpook
Senior Heliman
Location: West Wales, UK

BTW Disc, who did the paint job on your canopy?

Am I still in control?......................OH!
03-03-2007 Over year old.
 
 
Disc
Heliman
Location: Lincoln,UK

The Knight came to me 2nd hand and was already painted although it doesn't look that good now! I have had several issues with it but we had just got it flying smooth and nice.

Mount broke at the 2 lugs that hold the servo in place.

changing it to a Knight sport or 3D servo mount.

I wasn't going to order the parts for a while but sod it I want to fly it again. so ordering from skyline models on monday.

Oh I agree for the money its a dam fine machine just a couple of niggles thats all. But I agree it is hell of a machine for the money.

Kesteven Model Flyers, UK
03-04-2007 Over year old.
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Chariot
Heliman
Location: hong kong

first lot

second hand, that explains it.
you probably got one of the very first lot i think. first lot of Pro version came to HK with a piece of square metal (kind of) tail servo mount attached on the body. Compass soon changed the shape of that piece of metal and make it a lot larger. I was wondering why. i am using a plastic boom mount from Knight sports or 3D. it is fine. But the tail linkage length is different. you probably need to get a sports tail link rod.
03-04-2007 Over year old.
 
 
petmotel
Veteran
Location: DeKalb, IL.

Disc, I have an all metal Knight with one of those very mounts. That thing is solid as a rock, and I would not believe it likely to fail under normal circumstances.

The aluminum that the plate is made from does, however, weaken severely when it's been bent. As you acquired this heli used I'm wondering if it's possible the plate was bent by the original owner and bent back? This would of course leave it (or any aluminum alloy for that matter) highly prone to stress fracture.

Whether or not this be the case, it makes a good point to replace any alloy part that has been bent, or damaged.

I hope you will take this into consideration before coming to the conclusion that the part failed due to poor quality or design. I know that I would have no qualms whatsoever just replacing the plate, and getting on with it. But then I didn't just crash my bird either.

Edit: just looked at the photos in your gallery, and no my pro Knight has the boom mounted tail servo, not the frame mounted version. I bought another metal Knight a couple months ago with the plastic tail, and that one came with the frame mount, but I didn't use it.

Jay
03-04-2007 Over year old.
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Disc
Heliman
Location: Lincoln,UK

This Knight has never been bent until I did it

If you start to hear a metal twanging sound your mount is on its way out.

I have now heard of a few of these mounts going in flight maybe 3-4 so it might just be the odd few with an issue.

Maybe the reason why now its a diffent mount as well or just easier to produce one for all 3 machines?

Who knows, but it was a failure and thats that.

Oh well could of been worse.

Kesteven Model Flyers, UK
03-04-2007 Over year old.
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Rodney
Veteran
Location: Tavares,Florida

Disc check the shaft that goes from gear to pully for the tail. I bet it is bent. That would cause the vibration that would have caused the tail servo mount to break in flight. I had problems with mine breaking rudder servo arms after a crash. That shaft is what was causing it. Would have broken the servo mount except I am using the plastic version.
03-04-2007 Over year old.
 
 
Disc
Heliman
Location: Lincoln,UK

Hang on an un-crashed machine could have a bent shaft in it...

Oh thats really good.

All parts ordered but I am bound to of missed something off!

Gone for BBT Manic blades again also the plastic servo mount and 2 booms/mainshafts/flybars etc.

I do not like wasting money on postage I always get a few extra parts in one go.

Kesteven Model Flyers, UK
03-06-2007 Over year old.
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larren
Senior Heliman
Location: Malaysia

Hi,

I have experience crashes before due to broken tail servo mount on metal Knight. But now I already had many gallons without any issue since I use double (2 pcs) tail servo mount.

Larr.
03-06-2007 Over year old.
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Compass Knight 50 > Knight Tail failure....
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