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Futaba-RC . A Main Hobbies . Boca Bearings

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Off Topics > Metal Blades used during demo at 3D Masters
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

I always find it amazing and disturbing how some people will make conclusions about something that they know nothing about just because some larger body has said so.

To those people I ask,
Do you like having someone else make up your mind for you?
Is it too much trouble to think for your self?
Are you always so willing to give up your freedom of choice?

Before I agree that metal blades are bad, I want to see some hard data. Unsupported conclusions don't cut it. Just because knives are metal, you assume rotor blades are the same ???? When was the last time you saw a metal rotor blade slice through a pork chop?

I'll get off the soap box now.

Wolfgang
08-06-2003 Over year old.
HOMEPAGE  
 
 
J2M
Senior Heliman
Location: UK

I talked to Karl-Heinz about his heli at the Masters. He told me that his blades are made from specially extruded aluminium sections. Can't see any issue with that myself providing he's done his design calculations correctly.
08-06-2003 Over year old.
 
 
pilotError
Key Veteran
Location: Long Island, NY

Metal Blades

There was some discussion about this sometime ago in the Scale heli section (old RCO?).

If I remember correctly, the opinion of choice was that the metal fatigue's over time, and it was beyond the average modelers means to have the equipment available to check it.

Here's a link about the same discussion on another forum

http://www.flightlines.com/forum/Fo...TML/002245.html

Good Judgement comes from Experience. Great Judgement comes from Bad Experience.
08-06-2003 Over year old.
 
 
RotorX
Key Veteran
Location: London

I have seen the damage done by wood blades off a rap50 to someones leg, he got away verly lightly, i think (in terms of scars)

I have seen a friend arm after carbons hit - nasty scar that has a 2 inch width and is almost 5inch long also rap50

I dont know if how strong ali is to carbon, but i do know it won't shatter like carbon dissipating some of the force ,

I would think that ali would be stronger at the root of the blade, but i dont actucally know that for a fact.

I know this much you dont need to be a brain surgeon to figure that they are more dangerous if impacted with human,

Cause when we talk safety, firstly we ensure the safety of the human, then his possesions. so far as humans go they are more dangerous.

That is not to say i would not use them, but accept min. increase in the risk in operating a model with ali blades, that all

Kaz

08-06-2003 Over year old.
 
 
crash1953
Veteran
Location: Washington State

I cant say anything about metal blades , but I had a heli dumped close to me once and the blades went everywhere . They were like bullets and darts ..I think I could have been killed very easily with those blades seperating from the head .. Now Tell me again what is wrong with a metal blade just folding around the helis head in a crash?? At least it isnt flying out to kill someone else too .. The only thing I can see that might be wrong with metal blades is fatigue.. How many hours can you fly them ?Blade flexing will have to show up sometime as fatigue..When it does I would think that would be when there is a danger of a seperation from the heli.. Also I wonder about some of the other blades and fatigue.. What will that happen to carbon? How about fiberglass and wood?? I know there is a very big issue with wood blades and gluing the ends on .. I have never seen one seperate ,but I have heard about it alot .. Sounds to me that alot of this controversy might be that some people just dont take responsibiliy for their actions and want someone else to blame all their problems on ..So when someone makes those decisions ,they will complain that in that case they know better than the people they elected to make those decisions..I would also like to see the research that has been done by metal blade manufactures.. If nothing else it would help me in my continual quest for knowledge and stupidity..
08-06-2003 Over year old.
 
 
Raffy
Key Veteran
Location: Chicago, Illinois

SAFETY ought to be the number 1 issue that need to be a concern. You all need to understand that a great variety of kinds of people are in this hobby. There are less professionals than Mr. Know it all and beginners and how about those daredevils?
Do we need a coffin to realize what a flying SAMURAI can do?
08-06-2003 Over year old.
 
 
T.C.
Veteran
Location: Nottingham. England.

M Blades

Hi Erich,
If i saw you on my field flying with those M Blades I'd be hiding behind a very large tree !!

In fact I got the urge to hide under my desk just looking at the photo

Cheers. T.C.



Tony
08-06-2003 Over year old.
 
 
T.C.
Veteran
Location: Nottingham. England.

Pork Chop

This one's for wolfgang,

How many pork chops have you thrown at heli blades then ??



Tony
08-06-2003 Over year old.
 
 
Erich
Senior Heliman
Location: SouthernCalifornia

TC

If i ever do fly those blades..........I'll be hiding right behind you and the tree

-
08-06-2003 Over year old.
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

T.C.
I've chopped off twigs with my CF blades and kept flying. No damage to the blades. The sound could be easily heard 800 ft away. Are you still going to tell me that CF blades are safer than metal?

Raffy
The last time I looked, "a flying SAMURAI" had a rather sharp edge. What does the leading edge of your blades look like?

Wolfgang
08-06-2003 Over year old.
HOMEPAGE  
 
 
T.C.
Veteran
Location: Nottingham. England.

Wolfgang,

I think CF or Metal are both going to hurt like hell, but given a choice ? I know which ones I would choose !

Check out these photo's ( you may have already seen them ) & make your choice.

http://runryder.com/helicopter/t54491p1



Tony
08-06-2003 Over year old.
 
 
tech1
Senior Heliman
Location: Mississauga

A high performance race car is designed with a crash in mind. The car should dissipate as much energy as possible to reduce the forces on the driver. This is engineered in.

I don't think our CF blades are designed to break up in any specific way. As far as I know the blades are designed for strength and airfoil design.

As long as the airfoil shape remains I would think the CF blades could be as strong or stronger than metal on impact.

If anyone wants to try I know where we could get a cheap side of beef to test it out on.


Nothing is fool-proof, to a sufficiently talented fool.
08-06-2003 Over year old.
 
 
Dragon2115
Key Veteran
Location: New England

The big danger of AL blades is fatigue. Micro fractures form at some point and eventually is followed by catastrophic blade failure. And you don't want to be around when that happens, regardless of whether it's a wood, FG, CF, or AL blade. I've seen it first hand and I can tell you it happens without warning and so fast you have absolutely zero time to react. As was said, wood, FG, and CF don't have cycle times like metal does. Unless you have access to the equipment to do a proper inspection of the metal blades you are heading for trouble. It's not a question of if. It's a question of when.
08-06-2003 Over year old.
HOMEPAGE  
 
 
G.Man
rrProfessor
Location: Northants, but soon to be Nicosia, Cyprus

hmmm

so how about the flexing of the aluminium in the blade holders/grips?

Surely they must fatigue as well if the aluminium blades do...

What about the lead in the CF and Wood blades?

Surely that is a hazard flying out of the blades in an impact?

Not trying to question the facts, just the logic of it all....



Don't Email me as I wont reply - PM Only (spam countermeasures)
08-06-2003 Over year old.
 
 
Raffy
Key Veteran
Location: Chicago, Illinois

Wolfgang,

The leading or trailing edge of a "Flying Samurai" dislodged from the heli gone bezerk need not matter if it is sharp or not! .....it is being swung at high speeds and you will need an armor for protection!
Knives my friend are handled carefully but if I swing it at you, I am sure you will try to defend yourself before it gets to you....I hope you won't have to ask me then, if the sharp or blunt edge is coming towards you.
08-06-2003 Over year old.
 
 
3dwanabe
Senior Heliman
Location: Concord, CA

Aluminum blades have the potential to create greater damage to flesh and bone than carbon fiber blades.

Carbon fiber composite is a very brittle material that dissipates it's energy by shattering, delaminating and splintering. Less force will be transfered to flesh because much of that force is dissapated in the blades as the material breaks apart.

Aluminum will transfer more energy to the body because it is mallable and has more density. It will retain more mass for a longer period of time after impact. There will be more penetration and trauma. As the aluminum bends and tears, sharp edges are created that will slice soft tissue until the rotating blades are no longer in contact with the victim.

Roy
08-06-2003 Over year old.
 
 
RotorX
Key Veteran
Location: London

3dwanabe

your description of why ali would be more dangerous in a crash with a human is spot on

Kaz
08-06-2003 Over year old.
 
 
aeromorris
Senior Heliman
Location: Murfreesboro, TN

Personally I'm kinda surprised that they anodize the blades. Sure it looks cool however part of the anodizing process requires that the blades be etched in acid so that the dye can weep into the resulting pores. I'm sure this weakens the metal. To what degree, who knows?

No doubt the blades look awesome, however they are not as reliable or as safe as CF or FG blades. I did research with one of my prof's back in college that dealt with the survivability of composite rotor blades with an emphasis toward military applications. The survivability of composites was much better than metal. For example, composite cracks do not propagate catestrophically through the blades the way metal cracks do. If a couple of fibers break, so what you have 10k extra to hold the load.

A lot has been said about the cycle life of these metal blades and I'm sure someone could come up with a pretty good theoretical approximation of what that should be. The truth is that in unless you fly several hundred gallons on the same set of blades you'll probably never reach their useable limit. The problem is that without a way to detect the presence of new cracks you have no way of knowing how far along the blades are in their life cycle. Therefore you're hovering a ticking timebomb.

With all this said, if anyone elects to use these blades, I think it is their right to do so. However, those who use them should not complain when their insurers refuse to provide coverage. I'm guessing that you wouldn't be allowed to fly them at any AMA sanctioned field as it would render the fields' insurance useless.

-J
08-06-2003 Over year old.
 
 
Nifty Nigel
Heliman
Location:

A few cents worth from me...

Metal rotor blades on model helicopters are ILLEGAL in the UK. Yes, it's in the BMFA handbook but it's also in CAP 658 (see http://www.caa.co.uk/docs/33/CAP658.PDF). The CAA's rules are not up for negotiation, they are the LAW!

I have no idea whether metal blades are good or not - the problem that I have with this helicopter being flown at the 3D Masters with metal blades is that although we can all now argue about whether or not they are safe, the people in the crowd weren't afforded this luxury. For the sake of an excellent display (yes, I though it was great) a safety decision was taken on their behalf which, had it all gone horribly wrong, would have generated a huge amount of finger-pointing by people asking why it was allowed to go ahead. I questioned the guys on the stand about this point and they brushed the matter aside (in the same way as the guy who tried to warn about the O-rings on the Challenger space shuttle I suspect).

The fact is that this was a risk that the organisers took. It paid off this time but someone might not be so lucky the next time.
08-06-2003 Over year old.
 
 
Augusto
rrAdvertiser
Location: San Diego, CA

Nigel,

Thanks for the info. So it looks like the Metal blades are illegal in the UK but as far as I know there's no rule against it in the US. If anyone has info on FAA regulations for the model helicopters then we could verify that.

Again, just so people don't misunderstand this, the reason why they are illegal in the UK is not because BMFA says so but because there's a statue that says so. In a similar manner rules by the AMA are not laws. The only time you are doing something illegal is when you go against the laws and not the regulations of an insurance company.

Augusto.

Avant Aurora Ultimate
08-06-2003 Over year old.
 
 
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