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Autography FlightPower . Advantage Hobby . Revolution Models

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Main Discussion > Dangerous Carbon-Fibre Blades
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

I hope you post this info on other forums as already suggested. They (united Hobby / Hobby City / whatever) needs to be held to account for this.

Quote 
.2000 max on the head could be something on the order of 4,000 to 5,000 on the tail for a 50 sized heli.

Most heli's I've counted run about 4½ to 4¾ - 1 ratio TR to MR speed so a 2000 RPM headspeed = 9000-9500 RPM tail rotor speed. (am I off here?)
I do know from experience it's important to balance your tail blades. I just bolt them together and add tape till the heavy one doesn't fall anymore.

...yep...
04-17-2008 04:30 AM
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

My EVO 50 manual says the TR reduction ratio for a 50 is 1:4.71.

I may have interpreted that wrong -- as the motor to TR reduction. It could also be the main rotor to TR ratio, in which you get nearly 5 revs of the tail for every 1 on the main.

That actually makes more sense (I was too lazy to go down to the shop, grab a heli, spin the mains and watch the tail).

That 8,000 - 10,000 RPM makes a lot more sense (my calculated 4-5K just seemed wrong in my gut).

So turning at 8 to 10K, the tails are even MORE susceptible to failure than the MR blades.

Thanks for the slap upside the head to get me back on the right track.

-----

* Making the World a Better Place -- One Helicopter at a time! *

Dave
04-17-2008 04:44 AM
 
 
himaxkeith
Senior Heliman
Location: Atlantic City NJ. USA

Not sure what my rpm was at the time but i remembered my last flight. Before I started to sling my tailblades I dinged the tail in the dirt when I landed everything looked ok never did I realize I bent the aluminum tail hub. Then I went thru some sets of blades before I found out what was wrong .I still have one of the tailblades with the bolt hole elongated.My digital camera is inop other wise I post the photo of the tail blade. But it looks the same as the posted mainblades.
04-17-2008 04:49 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.


when you think about the speed and size of tail blades we run it's amazing they can hold together without thrust bearings. That's also why I think the counter weighted tail blade grips help out so much.

Just thinking about how these blades could have pulled apart. It has to be straight up incompetence. Shouldn't the blade root be solid then drilled? They appear to be hollow?!?? I'm pretty sure my Radix are solid CF and they do not have a brass insert. Makes sense to me that they'd fail like this if it's just a 1-2mm of layed up fiber pulled against the MR bolt.

...yep...
04-17-2008 04:51 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

Quote 
That actually makes more sense (I was too lazy to go down to the shop, grab a heli, spin the mains and watch the tail).

btw - before my post I thought about going down the shop and verifying my thouhts, but got lazy

...yep...
04-17-2008 04:54 AM
 
 
helimatt
Elite Veteran
Location: Lafayette, IN

I'm going flying at lunch today and I'll take my blades off and check the hub- I don't even remember if they had a brass insert (I think they did).

Wouldn't any blade benefit from having a brass insert bushing; carbon fiber is very abrasive and could actually wear the bolt if it was bearing directly on the bolt. Plus its brittle, maybe spreading the load via the bushing has that benefit as well.

Never, ever, ever, ever give up.
04-17-2008 02:51 PM
 
 
helimatt
Elite Veteran
Location: Lafayette, IN

Okay I'm back (nice day for flying btw, but only had time for two packs). The blades were slightly crushed in a the root around the grip bolt hole- the shape of a circle nicely impressed about the same diameter as the end of the Trex 600 grip. I thought I could see a bit of a crease outboard of the bolt hole too. (Mine do have brass inserts). There was no evidence of tear-out at the bolt hole as in the posted pictures.

Now, maybe they looked like that when I first got them. I wish I had looked very carefully before installing them. But now with the reports, after four flights, I cannot justify flying them again. Maybe I'll find a clever way to reinforce them, but probably not worth the effort.

The Align B blades flew very well- they seemed about the same as the cheapies to me.

Never, ever, ever, ever give up.
04-17-2008 05:01 PM
 
 
nofear
Senior Heliman
Location: Chicago, IL

I fly the Maverikk G5 Wide Cord blades on my raptor and the Rotortech angled tip blades on my trex 600E and am extremely happy with both
types.

You don't need to spend a fortune to get good blades, but on the flip side you should not skimp out on a cheap set either.

The last thing you want is a blade letting go and hurting someone.
04-17-2008 05:04 PM
 
 
Rui_JC
Veteran
Location: Portugal

Hi all,

I have a brand new set of 325 carbon main blades that i bought from Hobbycity just a couple of weeks back.

I decided to buy them to see how they are.

One thing i can garantee you is that they DO NOT LOOK LIKE the ones in the picture that they have in their site.

The carbon pattern is not the same and they have a rough finishing.

I'm still considering if i will go for a test flight with my mini titan or not

I can post a few pictures of the blades later.

.

Keep it up...literally
04-17-2008 05:41 PM
 
 
Bad Karma
Veteran
Location: UK

This hobby isnt for cheapscates, I have known people who have really scrimped on things like blades, and it really does scare me what some people are ok with flying with.

To those that do buy cheap crap, either spend the £/$ on quality gear or get out of the hobby before someone gets hurt.
04-17-2008 07:52 PM
 
 
helimatt
Elite Veteran
Location: Lafayette, IN

Well, that's pretty good advice, and remind me not to fly when you are near by (for both our sakes I guess). I can't fault your reasoning, but your attitude..

Moving on.

Never, ever, ever, ever give up.
04-17-2008 08:43 PM
 
 
laughingstill
Key Veteran
Location: Gainesville, Fl, USA

UH OH...

3DMP-E, Logo 6003D, Logo103D Carbon and Trex 450se Flyin Firefighter
04-17-2008 08:49 PM
 
 
HuskyD
Heliman
Location: UK

I was looking at those blades for my Trex600 too.
I use the Hobby City carbon blades on my Trex450 and they really have been good.
However a mate of mine recently purchased a set for his 450 and the blades are twisted along their length. Obviously QA has gone out of the window with his batch of blades, which is a real shame as mine have flown really well. When he emailed them and sent photos, he got the same stock reply, "please send back and we will replace". Sending blades back to HK isn't cheap for an individual, so I don't think he's going to bother.
The thing is you can't just say "this isn't a cheap hobby you shouldn't buy the cheapest and hope to get away with it" (sorry I know it's not a direct quote, but it is close enough to your point) the important thing is that as a company if you make a set of 600mm blades, they should be fit for purpose, the buyer should not be at fault just for trying to save money when he can.

Your blades have most likely not been damaged by vibration, it's poor quality materials/components, poorly laid up. The problem may have been exacerbated by vibration, but it's not the cause, if it was there would be helis falling out of the sky every 10 minutes.

Looks like I will be sticking with SAB or Maniacs for my 600, I'm not about to risk it to save a few squids by buying from a company that doesn't seem to care about the dangers or customer satisfaction at the very least. I think Hobby City will very quickly learn that just because the customer is on the other side of an ocean, we can still vote with our wallets.
04-17-2008 08:50 PM
 
 
helimatt
Elite Veteran
Location: Lafayette, IN

Honestly I am learning (always), and this was an experiment- I think I pushed this one as far as I want to now.

Never, ever, ever, ever give up.
04-17-2008 09:02 PM
 
 
HuskyD
Heliman
Location: UK

Quote 
Honestly I am learning (always), and this was an experiment- I think I pushed this one as far as I want to now.
I don't blame you for trying, I would have because of my good experiences with the 450 blades, but not now having read about your experiences. Thanks for taking the time to share you experience and save me from a costly mistake, much appreciated.
04-17-2008 09:16 PM
 
 
Bad Karma
Veteran
Location: UK

helimatt there is nothing wrong with my attitude, there is however something wrong with the attitudes of people who try to do this hobby on the cheap, they should just leave and take up R/C cars or boats or something before they hurt someone.
04-17-2008 10:21 PM
 
 
meowsqueak
Senior Heliman
Location: New Zealand

I wasn't trying to do this hobby "on the cheap" - I had never bought main blades before and these just happened to be less expensive than the rest. I (wrongly) assumed that all 600mm carbon fibre heli blades were manufactured to some high standard for safety-sake and that these were simply cheaper because they were sold from Hong Kong.

I now know they are rubbish blades and I am happy to pay more for decent ones.

We all have a responsibilty as active participants in a market economy to seek out low prices (for the same item) and encourage competition. Otherwise we only have ourselves to blame when prices are unnecessarily high. Now I (and others here) know that these blades are terrible, I won't buy them regardless of how cheap they are.
04-17-2008 10:58 PM
 
 
HuskyD
Heliman
Location: UK

Quote 
helimatt there is nothing wrong with my attitude, there is however something wrong with the attitudes of people who try to do this hobby on the cheap, they should just leave and take up R/C cars or boats or something before they hurt someone.

There is an expression, our US friends will understand this too, what a crock!
Just because you try to be sensible about what you spend does not make you dangerous.
I used to race bikes and believe me everyone who wasn't sponsored tried their hardest to do things on the cheep, but none of us were dangerous. (BTW it isn't possible, you spend all you have on it and it still doesn't make you faster)
Elitism springs to mind.
Idiot.
What do you drive, your head up your own arse?
04-17-2008 11:19 PM
 
 
Bad Karma
Veteran
Location: UK

I didnt mention anyone and it wasnt aimed at anyone, I was just trying to say I have seen a fair number of people buy substandard parts in this hobby and then wonder why they fail.

Buy cheap buy twice.

Like in all other things, name brands are name brands for a reason.

Quote 
Just because you try to be sensible about what you spend does not make you dangerous.

There is being sensible and there is false economies, if its cheaper than all the rest, ask yourself why.

For comparable items if there is more than a 15% difference in price I ask why, how is company X doing the same thing so much cheaper than company Y.....
04-17-2008 11:45 PM
 
 
Blade_Master1
Veteran
Location: Canada

meowsqueak

Could you post full pics of all 4 blades together I would like see what kind they are and what the differrences might be ?

I'm expecting a few different sets from United

2 different types of 550's and a set of 325's

JM2C's :)
04-18-2008 01:55 AM
 
 
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Main Discussion > Dangerous Carbon-Fibre Blades
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