How are Propeller Blades Made ?

[rrmerlin60]

Hi,

I've been wondering, how are typical WW II propeller blades made. For example, the 24D50 paddle blades from the P-51D, has a large "bulb" on the root end, and some rings, spacers, and other hardware that cannot be removed once the blade is created. How did these parts go onto the blade in the manufacturing process ? What happens during restoration, if the blade is generally good, but these parts are damaged and need replacing ?

These aren't the best pics, but you can see there are ring shaped items that wouldn't fit over the bulbed root end of the blade. So how are these blades made ? I know the bearings are half-circles, so no mystery there. But some of these parts are continuous circles.

Thanks, Tom.

 

[FLYBOYJ]

Hi,

I've been wondering, how are typical WW II propeller blades made. For example, the 24D50 paddle blades from the P-51D, has a large "bulb" on the root end, and some rings, spacers, and other hardware that cannot be removed once the blade is created. How did these parts go onto the blade in the manufacturing process ? What happens during restoration, if the blade is generally good, but these parts are damaged and need replacing ?

These aren't the best pics, but you can see there are ring shaped items that wouldn't fit over the bulbed root end of the blade. So how are these blades made ? I know the bearings are half-circles, so no mystery there. But some of these parts are continuous circles.

Thanks, Tom.

This is a modern clip but the process has been basically the same for 75 years.

 

[cvairwerks]

There are also brazed multipiece blades and roller formed blades manufactured back in the WW2 era. Aeroproducts were brazed. About midway down the page, there are thumbnails of a Construction and Operations guide and a Cutaway Guide.

Aeroproducts

 

[GTX]

Well first a Mummy blade and a Daddy blade have to love each other very much....

 

[rrmerlin60]

GTX, I vaguely remember something like that in High School Health class, but I can't recall who makes the first move.................

No Donkeys ! I mean how does the ringed stuff get shoved over the large diameter root thingy. And no more Eastern Block contortionist explanations !

Cheers, Tom.

 

[Wurger]

IMHO you may find the answer in this ... especially in sections for the alloy and steel blades

http://www.nj7p.org/Manuals/PDFs/Military/TM%201-412%2013-Sep-44%20Scribd.pdf

and here ..

file:///C:/Users/Dom/Downloads/tuxdoc.com_propellers-12th-chapter-2.pdf

 

[Michael Hope]

The Hamilton Standard aluminum blades like you mentioned for the 24D50, are aluminum forgings. The blade surface/airfoil is forged and the blade butt is tapered to allow the two steel bearing rings to be installed. After the rings are installed the butt end is then upset to make the rings permanent part of the blade. The aluminum blade shank is machined with a radius that the bearing rests against with a matching radius when no chafing ring is used, or a chafing ring is used as a spacer between the two surfaces to allow for adjustment during propeller assembly. If the ring with the radius, beveled ring, cracks, the loading when the propeller is rotating will cause the ring to expand and jam the blade and not allow it to change pitch, which causes the propeller to lock pitch. In a worst case the hydraulic pressure for pitch change can cause the single to stop pitch change, and shear off the mechanism, and the other blades change pitch which causes a very bad vibration, which then can cause serious engine damage. If the bearing rings go below dimension on thickness then blade would be scraped. We do have the required grinders for resurfacing all four surfaces of the two rings including the beveled surface.
The other smaller Hartzell blades with a bearing surface are machined that way and then a split bearing is installed with a steel ring to prevent the bearing from sliding off the radius.

 

[Reluctant Poster]

Here is an excellent video on Spitfire V propellers. The British used "wooden" propellers which were actually quite sophisticated composites, sort of a precursor to carbon fiber. They were lighter than the dural versions.

 

[special ed]

As an "assistant apprentice propeller repairman" in the USAF Reserve, I was amazed to find the blades on the Hamiltons on the C-119 were held into the hub by four rings/chambers of balls as bearings. The balls went in perfect and at disassembly the balls had been covered with many very small flat surfaces due to the wear. They were only useful as slingshot ammo.

 

[rrmerlin60]

Gents, thank you. Michael, when you say "butt end is then upset to make the rings permanent" I assume that the rings are installed, then by "Upset", you mean forged into a shape that now has that large bulb on the blade root end ? And then it's machined nice and clean ?

Tom.

 

[pbehn]

As an "assistant apprentice propeller repairman" in the USAF Reserve, I was amazed to find the blades on the Hamiltons on the C-119 were held into the hub by four rings/chambers of balls as bearings. The balls went in perfect and at disassembly the balls had been covered with many very small flat surfaces due to the wear. They were only useful as slingshot ammo.

I think that is "Brinelling" caused more while not in use than when being used.