Consolidated LB-30/B-24A/MkI/II Liberator engines

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Feb 22, 2010
Hi Folks,
Something I have tried to find out about for some time now is, what are the small metal disks behind the props/spinners on the early unturbocharged Twin-Wasp engines?
Please tell me!




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Many thanks W.
Not seen that first close in pic, which is great, but have the second one.

TBH I doubt it is to cover those items you mention, as the tappets are at the other end of the cylinders ie the top, also all the ignition wiring would be in metal conduit piping to protect it.

I had a thought of something like cooling reduction, but your thought of air flow acceleration to aid cooling, is an interesting and more likely one. Certainly the second pic is of Lib MkII's in North Africa, where more cooling would be good!

You may well be right with the things you've said, it's just needing hard evidence about those discs/covers etc


Not exactly regarding the valve tappets ... the front "star had them in front of the cylinders at the side of it. It should be kept in mind that the early B-24 were poered by the Pratt & Whitney R-1830-33C-4G engines. So possible that there were other engine devices attached to the front and hidden under the cover.

But I agree , the air flow acceleration to aid the cooling seems to be the most likely.
They seem to have some thickness to them, and a pipe from the outer edge back to the prop shaft. My guess would be propeller de-icing fluid.
If it were just for air flow deflection, why would it be so thick?
Hmmm thanks S, that's a good call about de-icing, so possibly some form of thin circular tank, which feeds to the blades. You can see small pipes or wires coming out of the disc in the close-up pic.
I have to agree that it's not that thick, and would have be of a curved design to allow smooth airflow around it, to promote faster airflow.

Another intial thought I had was, if it did have weight to it, could it be an engine or prop vibration damper?

Something I've noticed is that there is a difference between discs in the pics of the LB-30/B-24A engine to the Lib MkII's. The Lib MkII's appear to have a lip or seam running around the circumference where the LB-30/B-24A engine disc doesn't?

Some time ago I emailed the C.A.F about this query, as their B-24 Diamond Lil was an LB-30, with these engines and the discs. The old gal isn't fitted with these now, so either they've removed them or changed to a diffent engines. Unfortunately they haven't replied to both of them.

Keep 'em coming....


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I can't remind myself if the LB-30/YB24/B-24 had the de-icing system for props. Perhaps it didn't because these even did't have the de-icing system for wings and the tail contrary to the later variants of the B-24. Also I would like make a focus on that the Consolidated (Model 31) XP4Y-1 Corregidor NX-21731 had them too although in a couple of shots it can be noticed that initially the disk ( cap ) was attached to the port engine only. I doubt the designer could have attached the de-icing system to one engine only while the second one could be without.

XP4Y-1 Corregidor NX-21731_e.jpg

XP4Y-1 Corregidor NX-21731_c.jpg

XP4Y-1 Corregidor NX-21731_d.jpg


the pic source: the net.
I have read about a propeller deicer system that might be what is in the photos.

IIRC the description said that the deicer fluid tank was in the form of a flattened donut and was located/attached directly behind the propeller hub assembly. The piping led to grooves in the propeller that allowed the fluid to flow via centrifugal force out onto the propeller blade. It also mentioned that the tanks could not be left in place if operating in tropical temperatures. Unfortunately there were no pictures with the description.

There is a method that uses what are called 'slinger rings' to help disperse the deicer fluid to the propeller blades - but they rotate with the propeller. However, it does not look to me as if the objects in the above photos rotate with the propeller, and the piping does not look as if it is in the right position to disperse the deicer fluid directly onto the blade.

blade deicer 'slinger ring'.jpg
Oh that way .. now I remind it myself as well. I agree it doesn't look like the one in the images above.
It also mentioned that the tanks could not be left in place if operating in tropical temperatures.
Here is LB-30 Liberator B.II crashed at Salbani, India in 1943 while with 159 squadron. Those fittings still seem to be in place despite the personnel wearing shorts and sola toppees.

Bit like the photo in post #2 above.
I looked around a bit more, and found the objects in question on a lot of photos of the LB-30. As pointed out by EwanS they were present on the Liberator Mk II in India, and I found the objects on BOAC LB-30s used in the Air Transport Ferry system (Return Fery Service) in the North Atlantic.

BOAC LB-30 transports.jpg
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Hi Folks,
Thanks W for the XP4Y-1 pics, yes same engines, and obviously they were messing around with various things, so we can take it, normally all engines would be fitted with them. Also thanks ES for the BII pic.

TP, many thanks for taking down this route, I really think this makes more sense. At another site i posted this, someone kindly posted this more detailed pic of the system.


As W says the discs look diffent to the slinger ring system, but I've just had a thought. What if the discs on the LB-30 engines were in fact covers for the slinger rings?

We're pretty certain these discs do not spin. So are these are un-spinning covers fixed to the crankcase, for the slinger ring de-icing system, that is attached to the hub and spins inside?


I do not think it can work that way. If I am visualizing things correctly, since the slinger ring and the slinger tubes rotate with the propeller hub, if the object(s) in question do not rotate they would sever the slinger tubes. And if the objects do rotate they would sever (or seriously displace) the slinger feed tube.

prop deicer system LB-30.png
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You make perfect sense...damn! ha!

Thanks for indicating it clearly, I did have doubts of how my idea would work.

So then, the discs are local (to the slinger ring) de-icing fluid supply tanks. If so, are they 'topped-up' from a larger wing tank? And if so, why have another tank in the system, why not just be fed directly from the wing(?) tank?


p.s Nice enginering background there. And maybe not a PITA, more like 'annoyingly correct'...;)
A small bit of info. Someone else has informed me that the B-24 de-icing fluid tanks were either 6 galls or 21 galls, situated under or behind the flight deck. But no info on the discs possibly being part of this system.

I have also just emailed the C.A.F again, the third time, about Diamond Lil, and if there is anyone who could help.


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