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Jabba29

CH-46 blade folding

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When the blades on a CH-46 fold, before this happens do the heads rotate so that the blades are in a certain position? If this is so, does anyone know the colour blade that is the master one and in which position it is in before the folding occurs? I have seen a video of the blades folding, but just folding and not that close that you can see what the colour of the blades are. Thanks in advance.

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I spoke with a former Vertol engineer who volunteers at the American Helicopter Museum today, during a visit and put your question to him. He said that there is no master blade. Whatever blade is over the fuselage serves as the master blade and the other two fold around it. In fact, he said all three blades go through a certain degree of folding during the process. The swash plate has to be tilted to a certain angle to facilitate folding too. I hope this helps.

 

LD.

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That help a lot indeed. 

 

I now do have another question, in that what are the colours used on the heads and rotors? Are they the same as those used on a Chinook in that they are Red, Green and Yellow?

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7 hours ago, Jabba29 said:

That help a lot indeed. 

 

I now do have another question, in that what are the colours used on the heads and rotors? Are they the same as those used on a Chinook in that they are Red, Green and Yellow?

 

Yes

 

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I don't think one blade can serve as a "pilot blade" in the centre. Because if say one blade of the front rotor was dead centre over the fuselage, the blades of the rear rotor are in the same orientation , i.e. one blade is pointing dead aft, the two near the fuselage are at 60° left and right of the fuselage. You can't fold the rear blade pointing aft forward as the rotor mast would be in the way.

Either the two rotors are somehow mechanically uncoupled and one is rotated 60° while the other stationary to have a blade from both forward and aft rotor dead centre over the fuselage,

OR, and this is what is happening I think, the rotors stop in an odd, off-centre position where all three blades of both rotors can fold into the middle without hitting the rotor mast. So no blade would be left unfolded this way.

Cheers,

J

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Thanks both for your help.

As an ex Chinook worker I sort of got how the blades are stopping, it was just if there was a blade that always stopped toward the front so that then set off the blade folding like the Sea King. 

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I would be inclined to think that prior to folding the FE would "set" the blades.  The system is a mechanical process and is set to fold to the rear and front, so you would have to position them in a certain way.  Other  wise you could end up with the blades folding 120 degrees to the fuselage.

 

The Marines routinely folded the blades on the 46's even when they were ashore so as to keep them exercised and in good working order. 

 

With the hooks we had to position the blades so as to tie them down to the struts, or on occasion to the eyes in the parking ramp.  But mostly to the front and rea struts.  the FWD RH blade and front blade would be tied together, the rest to the struts, absent eyes in the parking ramp.  I got real good a half hitches.  In the winter we generally tied the blade to the bird as it was a pain to dig the ropes out of ice filled ramp points.

 

When we put the ropes on the birds, you would always lag the blades.  So you can see where they rubbed on the fuselage on the sides.

 

Bryan

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Thouth I'd post a few images of the FWD head out and folded out.CH-46E_15xxxx_HMT-204_FWD_Head_CU_NewRiver_BryanWilburn_SM.jpg.2828f099a9f60231b8c52131e162453c.jpg

CH-46E 156477 HMM-264 Newriver 5-12-93.  Aft blades, Reb BL Left, Yellow is over the tunnel, BL R of the Green blade.

CH-46E_15xxxx_HMM-261_Nose_LHPF_CU_NewRiver_BryanWilburn_SM2.jpg.a97e87fbaeba1a2f6b9ce81ee1d2b540.jpg

Only have a BW of this bird.

 

- Bryan

Edited by BWDenver

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