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? See attched pic. Even the tome of all things Liberator, Peter Clare, doesn't know. We've tried to work it out, but no such luck...so if anyone knows, please tell me! Many thanks Shessi
My only suggestion would be some sort of air filter. On turbocharged engines the induction air entered via an intake on the (wider) cowling then passing through the turbocharger and intercooler and into the carburettor. The non-turbo R-1830-33 inducted air straight to the carburretor. Assuming this came from the engine front perhaps the domes are covering an air filter ? I note that Typhoons in Normandy were fitted with a similar shaped "mushroom" to cope with the unexpected dust.
Thanks L for the thought. Yes, I see where you're coming from. Initially I thought it maybe something to do with air intake, although there is no air or carb intake here. Behind the disc is just the crankcase boss for the shaft. The oil cooler/carb intake is at the top of the cowl opening, they are like a small scoops, which you can see in the pics. Elsewhere someone posted me this pic below, with two suggestions. One, that it's just a cover, and two, it's used to deflect and increase/accelerate the flow of air through the cowling. If you look at the below pic, and knowing what's behind the disc, I doubt(?) it's just a cover. But possibly, is it some NACA cowling cooling assist device? Keep those ideas/thoughts and info coming folks, thanks. Cheers Shessi
This is an anti-icing system, where you feed by a pump and a tube to the open inside of the slinger ring with isopropyl alcohol. The centrifugal force of the propeller will spread isopropyl alcohol from the inside of the slinger ring via other tubes directly out on the propeller blade to prevent icing.
Thanks Finn, Elsewhere, you may have seen it, someone suggested exactly the same. TBH, I think it's leaning towards a de-icing device, as nothing else so far makes any real sense. The LB-30 has a slightly different system to the diagram you're showing, but would do exactly the same thing. Your system is fed from a remote tank, to the disc that is fed from a supply pipe. The disc being fixed to the hub spins with the prop, which with centrafugal force throws the fluid outwards into the slinger pipes, and out up the blades. Simple and effective, like it! If these discs are infact local remote de-icing tanks fed form a larger supply tank, and the fact these disc are not fixed to the hub and therefore do not spin (or do they?), then how is the fluid supplied from them to the to the props? You can see a short supply pipe leading from a small block at the base of the prop in my last post pic, but how does the fluid get to it? I've just had a brain fart!, what if the discs we see on the LB30 engines were in fact fixed covers, over the slinger rings underneath?! So the slinger ring covers/discs don't spin, but the slinger rings are spinning inside? Thoughts? Cheers Shessi
Thanks Finn. Yes, I think that's how we we're imagining it working. And yes to a general description about supply tanks/location. Elsewhere, someone showed the discs couldn't be covers for the slinger rings, due to the layout of both. But, I'm thinking that possibly these discs were local de-icing fluid tanks for the slinger rings. But why not just directly supply from the main tanks in the wings, instead of having another tank in the supply system? Shessi
Hi Shessi Below you will read, how it worked on the B-24 aircraft. Manual revised 1 May 1945: Equipment: "Ice prevention fluid, isopropyl alcohol, is supplied to the slinger rings on each propeller by 2 pumps taking suction from a reservoir tank. On early airplanes this is a 6-gallon tank located under the flight deck and can be filled in flight. On later airplanes it is a 21-gallon tank located on the half deck, refillable only from outside the fuselage. PIug valves, normally safetied open, permit shut-off from tank to either pump. Valves are located directly under the 6-gallon tank, and on the 21-gallon tank installation shut-off valves are located on the aft face of bulkhead at Station 4.1 high in the bomb bay, right side." -------------- Propeller Manual: "90. Anti-icing system.-a. Anti-icing fluids.- Two types of anti-icing fluid are used. One type is a mixture of 85 per cent ethyl (grain) alcohol and 15 per cent glycerine. This fluid is used in installations which provide for propeller anti-icing only. The other type is 99 per cent isopropyl alcohol. It is used in installations having a single supply tank for propeller, windshield. and carburetor de-icing systems." It is very big tanks, so I do not believe the discs could be a replace of the mentioned tanks. Finn
Hi Finn, Many thanks for the info. Although it doesn't mention any remote tanks ie the discs, it may be because by 1945 or in fact by 1942 B-24's had the later model Twin Wasps, which were never fitted with these discs. Only the LB-30/B-24A/BII's that had the early engines, were fitted with these discs. Although I agree it's doubtful these discs were the main de-icing fluid tanks, they still may have been a remote type (being filled from the large main supply tanks) on the very early engines? I've just emailed the Commemorative Air Force again, the third time, to see if anyone is willing to help. Shessi
Hi Shessi, As far as I remember, the Liberator LB-30 was equipped with the Curtiss propeller hubs, and not the Hamilton hubs (later). I have checked the attached photo. Qantas Empire Airways had both LB-30 Liberator I and II in the fleet. Finn
Hi Finn, Not a prop expert, but it sems that the standard prop from Consolidated, even early models were Hamilton props. It seems that us Brits, did convert to Curtis Electric, but not on original LB-30/ LB-30A/ Lib I's, only on the LB-30B/ Lib II and C-87 models. BUT, both types of props had these discs. Either they were used on the Hamilton AND the Curtis props, or just the Hamilton and were left in place, redundant, with the Curtis props? Shessi
Shessi You have the designations muddled up. Early Liberators in the order of delivery were LB-30A - 6 ex YB-24 LB-30B - 19 ex B-24A. 1 lost before delivery. 11 converted as Liberator I for Coastal Command LB-30 - from French/British orders in 1939/40. Some of these became bombers or aircraft for Coastal Command as Mk.II. This was the first version with the longer nose. About 52 were retained by the USA after PH, some as transports and some as bombers. The USAAC/F gave up early Liberators after Britain/France had placed their order for LB-30. Hence the suffix given to these models when they arrived in RAF service before the latter. Early Liberator History is complicated!, Ewen
Thanks Ewen. I was just being general in trying to cover all the variants. Hmmm, I have info that LB-30's (not A or B) were GR I 's, and the ones kept by the US were designated A. It is complicated! What we really want though is...What are those discs for!! Shessi
When formed in June 1941 No.120 Squadron were allocated 20 Mk.I Liberators. (I might add that the Mk.I Liberator were the only VLR aircraft available to Coastal Command) These were to form the squadrons initial establishments of 9 aircraft and to provide for wastage loans and allotment of these Liberators during August and October to Ferry Command and B O A C. had by 9 October 1941 reduced the squadron to a total of 10 aircraft with no reserve for wastage except for for the probability of two aircraft which were being used for experimental trials. The first eight Mk.II Liberators fed into 120 Squadron were not fitted with A.S.V Source - The RAF In Maritime War Vol.III Part I (Air Historical Branch)
Hi Peter, Thanks for the titbit of info. As you can see my quest for the truth goes on... Both here and other places, it's been possibly narrowed down to, 1) Discs only fitted to early P&W 1830 engined LB-30's et al. 2) Discs fitted to engines fitted with both Hamilton and Curtis props. 3) Discs appear to be fixed to crankcase hub boss, and do not spin. 4) Discs appear to be connected by tubes/wires to the de-icing slinger ring/prop hub. Shessi
