Blades revisited. Dangerous shortcomings.

[Sesame]

Maybe we should all be treating them as a bit more of a consumable? 50 flights and then change for example? 100? 200?

Interesting, and if they should die before that number the manufacturer can cover the repair costs if any. LOL, not going to happen is it.

personnally when I see any signs of stress in the blades I will stop using them, as I mentioned before the chips all along the leading edge of the torsions, they never hit anything it was purely stress. Ive also had trouble with maniacs, weights comming loose, in that case the imported first of all accused me of abusing the blades, even though there are zero marks on the outside. ive been waiting over 2 months for the promised replacments from robbe even after numerous calls and proken promises. so im needing to find another blade type I like, therefore finding this thread extremely interesting

[Smoothound]

Tony, your biggest problem in the above is Robbe. They have no bad products until you rant on the forums then your replacements will probably arrive

[SRH990]

A friend at the club has already had a set of Maniac 703's replaced by Skyline due to the lead weighs coming loose and the weighted blade of the pair of Maniac 603's rattles a bit too.

The set of Maniac 2 703 blades I've got have an aluminium plate in the root through which the blade bolt bush fits, I know this because I had to drill them out to fit the 5mm bush, the roots are definately strong!

[barney]

Maniac 2 703 blades I've got have an aluminium plate in the root through which the blade bolt bush fits,

Interesting Steve. This is the kind of info we need to build up to weed out any potential shortcomings in blades. I'm sure there are a few other folk with a stash of broken blades just waiting to be cut up for inspection...

To keep things roughly the same and tie in with my photos it would a good idea to cut through the blade hole and approx 1-1/2" further outboard as I have done.

The out board cut shoes the Spar system or lack of it/Foam core etc.

I would really like to see Some Maniacs, Radix 689/standard and Stickbangers chopped.

Also really interested in the SAB Red Devils both the new Trex 700 specific blade and there original 690/710 Red Devils. Be interesting to see what differences there are as SAB apparently had an issue hence the specific blade now offered for the Trex 700.

[barney]

Another two blades straight from the chop shop. First up is a Radix 690 Stickbanger. Looks to be very similiar design to the Radix 600 I posted further up the thread. Notice the even heavier retaining wire for the tip weight and the tapering solid core as you move further outboard from the Root. 2nd photo is of my equally inquisitive helper Stu doing the chopping.





Courtesy of Stu's collection is a budget 600mm blade. A JP.. Perkins? This has a solid Root with a wood spar extending through the bolt hole. Externally it looks similiar to a SAB like but that means nothing.

[Stu.]

Yep Perkins blades there.

i have to admit the chopping procedure varies from hard (Radix), to incredibly quick and easy (Perkins)

Atl least perkins are cheap!

Stu.

[Janek]

One thing I noticed in the earlier pictures taken from above, at the face of the roots, is that all your used blades have scuff marks from rotation in the grips ?

How tight do you run them ?, what short of headspeeds ? are your grips OK ?, how often do you change blade bolts ? are your bolts undersized ? could any of these be factors ?

[moyesboy]

A reminder of this thread on the same subject:
torson 315 broken at root (both the same, in a crash, no funky chicken though)

I've been running GLX600 for a while now and not seen any issues at the blade root.
I'll have a pick through my remaining broken blades.

I would be very suspicious of any blade that breaks near the bolt hole in a crash.

The other factor is I wonder how much extra stress goes into the blades via metal grips rather than plastic? If you can tell the difference in the flying then there must be more stress going into the blade for sure.

We could start wondering how many hours of 3D a plastic, or metal blade grip is good for. They will have a finite life for sure. Pastic will depend on how many hours of sun it saw too (so the USA pilots will test that for us!).

[barney]

Pastic will depend on how many hours of sun it saw too

PMSL..USA Pilots..Only to true on that one.

Metal Grips verse plastic..Metal grips are harder on the blades for sure, no doubt about that.

The scuffing on the face where the washers/Grips fit should make no difference as this area is generally solid or heavily re-inforced (or should be at least).

I run my all my 600mm plus size blades tight to prevent boomstrikes at the bottom of autos. Headspeeds are all well within recommended limits..For Example 600mm 2100 Trex 700 1950. The Torsion 690's being rated for up to 2400Rpm.

Its nothing specific to my machines as its occured on several models with 2 different brand blades. I have also heard of a few others.

It seems very obvious to me its poor design, material or construction methods.

[rchelispares]

by running the blades tight is there extra load being placed on the blade...as there is no bending allowed to happen which could cause cracks around the bolt

[Paulice]

7 years ago now i had a set of Aluminum tail blades fail at the root on my futura 60, it happened in the air and quite high up,(the heli was a right off) we found the blade and sent them back, As the blades were sent to the shop i worked for for testing i got a new Millennium as the futura was no longer available, I'm not going to mention the make as i know there blades are now 100%, But i don't recommend anyone flying with Alu blades, and i think in the UK it's not allowed.

[barney]

Rotor blades should not be flexing across the bolt hole between the grips. Blades are tight but not solid by any means. Tight enough to require a good firm shake with heli on its side but loose enough to straighten out and lead lag as they should etc.

[barney]

Nice one Paulice..you are correct we dont allow metal blades over here. Aluminium is prone to fatigue failures over time and quite surprised to see it used for a tail blade. Thanks for sharing.

Brian

[Toolman]

Interesting thread this.

Does anyone happen to know if SABs use a wire tether on the weights?

Also I believe that Align blades do now, is there anyway to know which part types do?
Thanks

Tim.