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08-17-2010 03:48 AM  10 years ago
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Peter Wales

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Orlando Fl

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New blade rules
Earlier this year I had some carbon blades and some metal blades lab tested against each other from a safety point of view. I sent the results off to the AMA Safety committee and asked if we could be allowed to use metal blades under certain conditions.

After they reviewed the results, they said yes, and sent their recommendation to IRCHA for their input. They said yes subject to certain conditions

I asked if we could have a minor change in those conditions and the results went to to the AMA Executive committee for approval this weekend.

It was approved unanimously

So, as of Jan 1st 2011 a rule change will be in force which states

Metal blades may be used under the following conditions

1) Only on models weighing more than 20lbs
2) Only on models with a disk diameter greater than 1800mm
3) Not on Aerobatic models
4) A log must be kept of all flights using these blades.
Peter Wales
http://scalehelicopters.org
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08-17-2010 04:50 AM  10 years ago
PETER ROB

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Devon UK

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Metal blades

Peter, What a great step forwards
Metal blades were flown here in the UK at a meet at the begining of the season, by Matthias Stump a guest German flyer, The ruling body here were in agreement providing the flyer had the correct insurance
Well done again Peter
Let's hope that the BMFA here in the UK can see the light, and stop hiding behind the insurance rule
Peter R
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08-17-2010 10:40 AM  10 years ago
modtron

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Oxford. UK

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We are already making progress in the UK with M-Blades.

The paper work was submitted to the BMFA some time ago and they have agreed that it needs to be looked at.

It will not be a quick process, but as Peter has established - it's worth pushing for.

Thanks for your help Peter, and I hope that we will follow very shortly.

modtron
Oxford UK
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08-17-2010 12:37 PM  10 years ago
bwellmaker

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Long Island

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Great News Indeed.

All of my 76 flights have been with metal blades. The only flight I have made with carbons, was over the past week. There is a huge difference in performance and efficiency for my application.

Thank You Peter for spear heading this rule change.

Butch
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08-17-2010 01:57 PM  10 years ago
helibeli

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wales.uk

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Can someone list the pros and cons of metal v carbon v grp blades for all to see?
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08-17-2010 02:02 PM  10 years ago
GyroFreak

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Orlando Florida ...28N 81W

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Can someone list the pros and cons of metal v carbon v grp blades for all to see?
Yes, excellent suggestion.
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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08-17-2010 02:08 PM  10 years ago
fla heli boy

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cape coral, florida

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interesting.....
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08-17-2010 08:36 PM  10 years ago
ScaleNewbie

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Ryde Isle Of Wight UK

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isn't this a step backwards ?

I read the big debate on the freak,my question is when full size are moving away from metal and moving to composite beacuse of strength and reliability why are we trying to go in the oposite direction?

Metal blades in full size are houred will the BMFA/AMA put a limit on the flying hours ? and then expect an exemption cert from a reputable tester before we can fly with them again ?

Apart from the nice droop you get when blades are stationary i would hesitate to say they are stronger than the carbon ones we fly with..

I am open to new ideas and applaud progress and the hard work being done, but apart from the droop and the fact they may wrap themselves around the mast in a crash there is there a further benefit to using them..?

Arent our compsites are much more stronger ? and when they start to stress fracture you can visibly see the cracks where as in metal blades you wouldn't unless looked at under a microscope..

Ryan
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08-17-2010 09:08 PM  10 years ago
ScaleNewbie

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Ryde Isle Of Wight UK

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found this info on a composite verses Ali rotor blades....

The lifetime depends on the material the blades are made of and the type of rotor, composites blades are given to have a better resitstance in fatigue than metal ones, a best behaviour to environment.. the problem bein UV sensibility. how do you repair an alu blade ? in a composite one, if the fiber core is not broken it can endure a small impact and allow landing... are you a fisher ? i mean bass or salmon fisher ? remember duralumin fishing rods ? (i broke a few) no comparison possible with fiberglass or carbon ones, never broke one.

ok a composite blade may have delamination problems due to bad composites cooking, but when it happens you sould see it , while in an alu blade if a creek appears due to a scratch or bad handling, shock, it may cause a "flash" rupture, excepted if you control the blades before every flight with appropriate materials (detection fluid).

you must also say that metal blades are sensible to dusts and sand while composites endure them better, composites are sensible to rain while alu is not (during flight).
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08-17-2010 09:23 PM  10 years ago
Justin Stuart (RIP)

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Plano, Texas

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Do metal blades have a better sound? What is the benefit? Why not just paint some CF blades to look like scale blades?Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives
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08-17-2010 09:43 PM  10 years ago
v22chap

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Granger, Indiana

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Guys read the whole thread ... and understand what the first place winner of this years scale NATS said about alum verse carbon
All of my 76 flights have been with metal blades. The only flight I have made with carbons, was over the past week. There is a huge difference in performance and efficiency for my application.
Larry C ----------Bergen R/C helicopters
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08-17-2010 09:56 PM  10 years ago
Heliguychris

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Perth, West Australia

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Is it the same flexibility that allows the blade to droop, when stationary, allows the blade to bend in flight to soak up windgusts, etc, on a ridgid rotor head ? That would be the only advantage i could see??? Id not really like to see newbs roaring around the clubs with metal blades

How much do they weight ?? What do metals bust up like ? Im supposing they dont shatter like carbon, they would bend and wrap ?

Man you scale guys are a lot more hardcore than i thought
Licensed (CASA) UAV operator certificate holder 1-YFOF5-01 www.helicamaerial.com.au
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08-17-2010 11:08 PM  10 years ago
bwellmaker

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Long Island

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I have no scientific facts, none. Maybe Peter will chime in here with some technical facts he may know from testing to help out.

For my application, there are very limited Carbon blades available. My Peka head has a 14mm grip. Vario does make some really nice big blades however, they have a root of 22mm. My 76 tips the scales, flight ready at 41lbs, therefor, I need some pretty big blades.

My 950mm M-Blades weigh in at 337g, the 875 OF blades are 333g. The CG for the M are 540mm from the bolt hole, whereas the OF is 460mm. As we know, the further out the CG, the more stable, within reason. Also being multi, stability is king.

The M-Blade airfoil is thinner by about 2mm. When I got home I did download the ICE for my last 2 flight and bounced the data off what I had saved from previous M-Blade flight. I was surprised to see there was not as much difference as I expected. The M-Blades were a bit more efficient but I am sure it was not the exact flight profile as flown with the glass blades. I will be doing some checks with both M and glass in the next few days to compare the differences, if any, and work from there.

The difference to me is how it feels. The M gives me a better feeling of precision whereas the Glass of is a looser feel. Neither are bad, both are desirable, but its that balance I look for.

Our flight profile is a bit sedate compared to other styles of flight. Stressing a blade may not be as much of a concern for a heli with a 950 to 1000 head speed

Don't know if this helps but...

Butch
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08-18-2010 12:59 PM  10 years ago
Peter Wales

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Orlando Fl

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I have had this debate with the AMA and convinced them, I dont need to have it again on each of the forums I have posted this news in.

As Butch says, the metal blades feel better in flight, and that makes them more desirable, but the main reason for promoting them was that GRP and CF blades tend to soften and deform when flying above the exhaust of a turbine. I have replaced the blades on my EC135 twice because the weave was showing through the gel coat.

I can find no reports of an M-blade failure anywhere and I have searched all over the internet and used all my contacts in Europe to try and track a failure down.

I had the laboratory run the tests on a brand new set of CF blades against a well used 10 year old set of M-Blades to find out if there were any stress fractures in the M-Blades and the results were very comparable.

This is part of the information I sent into the AMA
The test was done by loading a piece of the blade material with a weight and then placing it in a temperature controlled oven and increasing the temperature over time until the weight caused the material to lose it’s strength and deform. The tests were repeated twice as the laboratory considered the results much lower than they anticipated, but repeating them with a different load shown similar results. It proved that the Carbon blade failed completely at 255 degrees centigrade and at a temperature 100 degrees above that, the metal sample showed miniscule deformation of 0.05mm and was beginning to deform progressively. The defined melting point of aluminum is 660 degrees centigrade so it can be assumed that the material will degrade progressively more rapidly as its temperature increases towards the melting point, failing significantly above the fail temperature of the CF blade.
Several other tests were done as well and they showed that metal blades had similar strength properties to CF blades. Another big advantage they have is that in the event of a crash, they bend. They do not shatter and throw lumps of lead filled carbon fiber around.

BUT, if you get hit by a metal blade helicopter, it will kill you just as dead as a CF blade helicopter.
Peter Wales
http://scalehelicopters.org
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08-18-2010 01:05 PM  10 years ago
modtron

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Oxford. UK

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Just to add to Peters comments.

I found that as they are also torsionally stiffer and do not twist in flight and they are much quieter when being used.

In the long run, safer on turbines, quieter and more accurate.
Just waiting on the BMFA now, but the signs are good.

modtron
oxford UK
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08-18-2010 04:37 PM  10 years ago
Rodan

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Prescott Valley, AZ

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Are M-Blades the only metal blades currently on the market?

Links?
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08-18-2010 04:49 PM  10 years ago
modtron

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Oxford. UK

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As far as I aware, YES.

You must be aware that when you order any blades from Jahn at M-Blades, they can sometimes take many months to be delivered as they are made to order.
When you fly them, you know if was still worth the wait.

modtron
Oxford UK
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08-18-2010 06:29 PM  10 years ago
wingtip

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Indiana

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isn't this a step backwards ?

I read the big debate on the freak,my question is when full size are moving away from metal and moving to composite beacuse of strength and reliability why are we trying to go in the oposite direction?
The main advantage is for the turbine guys. Ive heard stories of having to replace the carbons once a year due to the heat weakening the glue on the blades and de-laminating them...

That alone should be reason enough.... and as for the full scale going to carbons and why are we going the opposite direction? Lets face it, rc heli pilots crash a HELL of a lot more than a full scale pilot... and as peter has experienced, carbon debris in your skin from an accident is a painful experience and hard as hell to be removed from your body cause its a million seperate splinters...
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08-19-2010 12:05 AM  10 years ago
ScaleNewbie

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Ryde Isle Of Wight UK

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The test you describe is no way a true to life scenario for the life of a blade on a helicopter.

Blades are subjected to stress not heat, the test that you have done misses the point,until you do a stress test in the same way they do full size helicopter blades, comparing the metal against the carbon, you cannot say your metal blade is safer than carbon..

You will aruge that carbon dont get stress tested, BUT carbon have an international world wide track record of safety,through competition use and use from the normal public, the metal blades have no such record.

I find it very telling that the authorities have slapped on these restricitions as to the use of these metal blades which goes to show how confident they feel about their integrity..

the issue is not how the helicopter is being flown, it is the issue of LONG TERM METAL FATIGUE. which is known and documented... in metal blades.
Carbon blades do not suffer from any of these issues..

If its true and your blades are suffering from exhaust blast aliminium foil which is used for exhasut lagging can be stuck to the underside of your composite blades and that would dissapate the localised heat..
I have seen this on MattJenns Longranger and he has been flying for over a year with MAH blades and no delamination has taken place...
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08-19-2010 01:20 AM  10 years ago
MattJen

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UK

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Hi Peter/Modtron

Your efforts must be applauded, as getting this through our governing bodies is no mean feat.

I can understand where you are coming from and what you are trying to do, the only thing i will say is these blades are NOT as strong as carbon, maybe in a direct heat setting they are, but if you used a 2 stage turbine instead of a single stage with all that wasted thrust, then maybe it will be different

The way to really test these blades is to give them to 3D guys who wang there machines around, and push the limits, carbon has been prooved and well documented to be a superior material.. if they hold up to the 3D guys then us swinging our blades at 950-1200rpm will be well within their limits..
When they get to 100hrs or the same level that carbons are used then we can 100% say they are as good if not better..
When most of these ali blades are used on machines that are taken out just a few times a year - even one poster here said 75 flights, well that probably equeates to 13-15 hrs, not long at all, but it is a start...

I only used the ali foil as you made a point of heat soak, i thought about it and as i needed blade wieght to balance them within a tolerance i find acceptable i thought i could kill 2 birds with one stone..
I have held a set of these blades yes they are nice and look the business, my suggestion or idea thinking out loud would be like some of the full blade manufacturers do, is when they are made is to fill them with a dye/liquid so when stress cracks start to happen you can see the liquid eaking out of the cracks,and you know your blades are no longer airworthy.. but we would have to make a rule that if you fly metal blades you cannot paint them.. that is my idea and opinion only...

This way is full proof against pilots not correctly logging their hours, or swapping over ECU's for a lower hour one when they reach their hourly limit, i know most wouldn't but we all know there are some who will break the rules, and all it will take is one failure and we get FAA CAA stepping in and making rules left right and centre.. which NONE of us want..

Once again Pete I applaud the effort of you and Modtron.

Matt

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