powerandpassionEasy to get the insects mixed up, Mosquito, Hornet ! The hook gear looks very similar, would still be very interested in getting a few detail photos if anyone wants to risk the roundabouts in.
powerandpassionWow Scotavia, great information, thank you ! Is anybody visiting there soon ? Can anybody take some photos? Very interested in internal details like reinforcing timber work inside the fuselage, as well as external details, mounting arrangements, thank you in anticipation ! Ed
powerandpassionNicko, I agree that most pictorial evidence, op cit and Mosquito Monograph, show camo on top and presumably sea gray underwear. What I can’t reconcile are remains, particularly mystery Highball bits, in PR Blue. I am forming the hypothesis that Highball equipped Mosquitos were kept in hangars while training hacks were parked outside. ‘Secret’ equipment in hangars was not photographed, while nosey locals could photograph hacks. Until more technical details emerge around Highball and Sea Mosquito setup, I am still just guessing. There are some books in the mail that may give some clues, hopefully…
powerandpassionNot sure. Often flew to Laverton in Vic and Bankstown for servicing. What makes you say Kingaroy? Was this a staging or training field?
powerandpassionWhat a brilliant pub! Great idea with the Cambridge aerodynamicists pulling beers. I can see an awkward silence where we work ourselves into a dumb corner and a deadpan bartender resolves with a comment out of the side of the mouth while pulling beer. In terms of subject matter, everything flows from a simple story or need. ‘Why the Whirlwind got its wings clipped’ which goes into the detail of the definition of an IC power plant : engine AND blades. This goes into breaking speed records then a jaunt across country in identical Cessnas with different blade setups. Second to the new pub in Scotland pays for the beer. You are ultimately appealing to the GA aircraft owner to explain 18% reduction in fuel expenses and 32% reduction in engine wear, as well as a few Texans trying to push Sea Furies past the sound barrier. Another episode is ‘Finding blades for a Napier Sabre’ which goes into manufacturing and national history, turning a RH tractor blade into a LH tractor, forging, a visit to a pub in the Czech Republic next to Avia, a visit to a pub next to a Jablo manufacturer in Germany etc. In truth just these two questions have enough meat in them for 5 x 30min episodes each, where the real challenge is post production editing of 150 hours of raw footage into 3 hours of final film. The whole lot can be filmed in two weeks, it will take 12 months to resolve a ‘guide script’ and 6 months of post production. Easy! The interactive bit is where it gets spark, inviting participation in evolving the guide script, and bringing interactions in during filming using actors to represent forum members asking questions, generally looking like scruffy out of work actors happy to be paid in beer! I really want to bring dead people in : a hyperactive Curtiss dissing Hamilton Standard, an intimidating Roy Fedden demanding Rotol, an angry Ratier chain smoking and carrying on about patent infringement, a totally intransigent Air Ministry official for numerous stage entries, various pilots in burnt flying suits talking about overspeeding an engine, failures in Fokker interrupter gear…there’s another topic : ‘I want to shoot through my propeller’ There’s a lot of fun to be had with that one!
powerandpassionA72945 May be fabric covered Hurricane, Henley or late Hart.
powerandpassionI think this thing is like a milkshake of historical context, eg getting DC2s higher and leaner, as much as ‘how does it work’ as much as ‘how can we get it to work in 2021?’ We introduce the hard stuff like lift and drag in between a bite of fairy floss like dH being wooed by Ratier and HS and why RR and Bristol went Rotol, using German technology. I don’t have a lot of knowledge of Curtiss Electric, and there is Fairey Reed too. A lot is explained by ‘difficult’ personalities – Fairey, Curtiss… they remain ‘known’ in history as ‘tough guys to deal with’ while the smooth, effective, high EQ HS key driver does not. I am sure this person was compensated by having a very, very large yacht. HS went global while the others did not. I understand Japanese props were HS licence, I am sure the Russians copied them too.
Following is some guff on magnesium blades – I think uniquely British, even the Germans with their Teutonic love affair with magnesium didn’t seem to go there. Again it is context of history, 1940, Britain all alone, with dH having a licence for HS products, while the US government could not be seen to be actively assisting His Majesty’s Government. So dH says ‘we have magnesium, so don’t have a lot of aluminium, can you please help us redesign magnesium blades, intrinsically 30% lighter, capable of narrower shanks due to lower centrifugal forces’. No doubt HS would say, ‘sorry, too busy, but you go for it, happy for you to design new blades that fit into our hubs’. So Brits start thinking about new blade shapes, then this leads on to optimising existing aluminium blades while they are at it. All this is surmise, it is ‘fiction that fits the facts’. However, two bloke sitting on a bar stool can get away with a conversation, and the skeletal remains of a dH blade designer can wander in to correct the record, which would be entertaining.
We shouldn’t write the script. We should just post stuff in the rainbow from hard facts to the ridiculous, and the interactive forum can drive the outlines of the script. A loose comment here or there can be a little glint that we can follow into a rich vein. After all of this, and reading lots of yellowing books, old controversies in Flight letter to the Editor and using modern forensic engineering, we can just end up in a pub yarning away, with actors doing guest appearances representing Fairey, Reed, dH, Halford, Fedden, Curtiss etc. It’s just banter with dead people. The pub ought to have some history, something with WW2 grafitti on the roof.
There will be many moments when the conversation will come to an irrecoverable end. For this we need a barmaid that knows more than us, that can steer things back on track. Because its all such a patriarchal history we can just take this deft intervention on board with a grunt and a fresh pint and move on. So Anneroac, up for barmaid? It’s kind of Arthur Daley, Del Boy and Rumpole talking about props, I can run with the fairy floss, you can try and haul it back to Reality and when we both hit a dead end the barmaid will fix it, just like women built the whole Air Force in WW2.
powerandpassionMate, I am up for something. I don’t think Millenials, who will really need the info, will know what a book is. For a technical topic, don’t underestimate the value of entertainment- Pilot Officer Prune led the way. My pitch to you is a series of YouTube’s linked to a website with reference and detail material. For the YouTube we sit in a good UK pub and just yarn away. We can script this stuff on this forum then sit down for two weeks in 2021 and film 10 episodes. The beauty of the forum is it’s interactivity which takes you down many pathways and can shape the ultimate episodes. This is not a money maker, but the pints should be tax deductible and we’ll get a laxative manufacturer to sponsor the filming to cover costs. How bout it? Some things that have come out from the interactivity of this topic on various posts are : (1) The folks who find this subject self evident are dead or on the ground trying to focus trying to find their teeth, therefore the information that they learned by osmosis in a career from 1920 to 1980 needs to be presented again, if historics are to be kept flying. (2) Folks are after the ‘look’ of blades for authenticity, without understanding function and there is a modern flight environment for display aircraft which may require a different function(3) a historic IC power plant is a combination of engine and prop, as the Whirlwind demonstrated. In this day of jet engines, this is not self evident. (4) Historic Prop design reflects national priorities – in 1935 in the US, sending DC2s from NY to LA for minimum fuel burn, in the UK rising up to a Zeppelin as fast as possible, never mind the fuel. The historic environment explains engineering choices as much as physics.(5) In 2020, we sit on the threshold of someone forging either new Rotol hubs to fit Jablo blades, or new HS blades to fit old HS hubs. Now is new 3D printing of titanium, pressure condensed hubs and components a pathway to short runs of historic components? (6) there is a tiny commercial market for optimised blades for the racing of historics, maintaining existing historics in the air in the face of diminishing supply of NOS blades and hubs or the return to flight of rare historics, eg those using British LH tractor blades. This market need technical support to navigate to an outcome. There is a role for a technical consultant, which is you Beermat ! But first let’s have a bit of fun developing a script for two weeks in a pub in summer 2021. For me, it’s the joy of learning. Should we start a new topic that lets folk ask questions about props on this forum to develop and guide a script? ‘Propeller Head’. Out of all the rants a motley crew can emerge that can guest on episodes, including dead people like the Wright Bros talking about their paddle blades, a crazed Frenchman called Ratier complaining about patent infringement, Constantinescu describing his first experiments with firing through blades etc. 2021 is enough time to book a ticket to a UK pub.
powerandpassionAhh, that’s Beermat with the good quote! I think in any difficult topic you need an Idiot and an Expert on the panel. Beermat is the expert. In the face of the wall of competence from the expert, most folks are cowed into silence. So the role of the Idiot is to get the Expert to roll their eyeballs and explain things s l o w l y using ice cream as an example…it’s amazing the illumination that can come out of basic principles. The Idiot, too idiotic to be cowed by the expert can also say dumb things like ‘ is that an iceberg ahead?’ which once every 28 times saves the ship, the other 27 times being saved by the Expert. Really what we are getting here on the fascinating topic of props is a barstool conversation, and I’m learning a lot and lovin it. Now does travelling through rain increase or decrease the speed of an aircraft, or does increased reaction of blades against raindrops balance increased resistance of fuselage to raindrops?
powerandpassionWhen I destroyed the industrial fan, I went into the library to hide, to eventually find an engineers handbook from 1890, which dealt with HP restrictions on steam engines, caused by cast iron flywheels shattering from centrifugal forces rather than the intrinsic capacities of steam engines. It was only after better metallurgy created stronger flywheels, able to resist centrifugal shattering, that more powerful steam engines could be developed. I think a 50 year old blade designer in 1941 would have learnt his craft on marine engines and marine propellers, so a lot of the basic stuff is there 130 years ago. Of course you can learn a little bit from reading and then you can learn a lot from making a mistake, which is a tough but good school.
powerandpassiondH also made blades out of magnesium, so the lighter blade might be that. Now I am not sure that Uncle Sam HS made magnesium blades, and generally if an aluminium formula worked and you had Alcoa, why change? Britishers finally made local magnesium from seawater and dolomite in 1939 and aluminium cost shipping and lives to U boats, and aluminium was needed for Spitfires, so magnesium blades were very attractive in 1941. Of course the big design issue is centrifugal force, as I learnt when over speeding an industrial fan, destroying it, so lower mass magnesium, for the same mechanical strength, could allow you to design a different shape, certainly less meat in the shank, a double benefit. I think fat shanks are about material strength and managing centrifugal and torque reactions. We don’t know about magnesium blades because it was probably just a British thing, it wasn’t needed after the war and whatever remained fizzed into powder.
powerandpassionOh this is getting controversial! Now you’re saying the Trump Mosquito paddle blade has eaten more hamburgers than the British Mosquito paddle blade ! I need definite proof before I hand good beer money over on this. As a separate issue, my understanding of paddle blades relates to my experiences with ice cream tubs. So the fatter scoop digs out more ice cream than the thinner scoop. Now change ice cream for air and the fatter blade is chippy-chopping more air than the thinner blade, at same RPM. I would want to do this if the air is thinner, way up. So I associate paddle blades with the race to go to 40,000 feet, stay above the flak and lessen the chance of interception. Then I have to rise in England and land in Russia, so I lean out my engine, balance power and RPM to ice cream scoop as much thin, icy fraulein deutcher air as possible for the minimum fuel spend. So that’s why I have paddle blades. After the war I want to send my DC4 as far as possible for minimum fuel spend so I stick with the paddle blade formula. Toothpicks fade from memory. Toothpicks were really about getting Spitfires and Hurricanes up as fast as possible in 1940, which is all Britain cared about then. Then I’m told I’m joining 618 Sq to Highball Japanese cruisers at sea level, where I want to transmit as much power as possible into thick air, so I change my Mosquito setup from three paddles to four toothpicks, back to trying to push as much air past me as possible. Now my big ice cream scoop, so good for pulling big scoops of watery ice cream might not be that good for pulling big scoops of chunky, solid ice cream. I might find weird torque affects when I push the throttle to the gate, chasing the devilish Luftwaffe. I really need a chopstick and to put the tub up to my mouth and flick little bits of delightful dairy goodness, or thick air, into my gob as fast as possible. In fact four chopsticks, Bruce Lee style, would be better than one. I am sort of exploring Force = Mass x Acceleratation, where air density influences Mass, RPM deals with Accelaration, where I am stuck with an engine, or Force, in both cases of 1,000 HP. Really I am trying to keep my RPM in a fixed range, so the Conrad’s don’t pop out, so I invent a constant speed airscrew which makes a blade fatter or thinner within limits. So flip-flopping between scoop and chopstick. Now later in the piece I am using 130 octane and getting 2,000 HP, so I am finding that I can actually push more mass, so I can use my big ice cream scoop paddle blade on a ground attack aircraft, where fuel burn is a non issue, because I am landing at an airfield only 10 miles behind the front. I hope this has lifted the scientific tenor of discussion and I apologise to any vegans for not using vegetable based analogies. I guess blade design comes from marine work and if you look at devilish torpedo blade setups and understand that speed through fluid with a short, brutal ‘fuel’ burn was the aim you start to see ice cream moving, or at least I do. Really the whole theory is there in the varying blade configuration in a jet engine, which was originally designed by Frank Whittle to make butter.
powerandpassionBeermat, dH Australia made paddle blades for Mosquito and many US types. The Corsair and Mosquito blade probably came from the same forging blank. DH Australia also made Fairey Reed metal props and later Hartzell blades until the 60’s. For anybody looking for Fairey Reed drawings for late 30’s Ansons, Gladiators, drawings exist at HARS Archives in NSW. Fairey Reed props are a limited pathway for low to high power fixed pitch LH tractor British radials to stay in the air, but these can, of course, used fixed pitch timber props. The real challenge are the constant speed setups of the 40’s.
powerandpassionI can’t think of any part of an an historic aircraft which has more punting and voodoo than blade setups. Only through the historical fortune of US radials and Merlin’s being RH tractor has a pathway to keeping many historics in the air evolved, albeit with ‘suck it and see’ engineering. Of course there are Jablo blades for Rotol hubs, but after the irony and cash spend are accomodated, until somebody forges more Rotol hubs, this pathway is petering out. Truly there is a good future in ‘standard’ E shank HS RH & LH tractor chunky forgings that can be machined to match original specs, both to please aesthetes and achieve original design function. Today CAD programs such as Solidworks can simulate wind tunnel testing and show in pretty colours how good, bad or ugly some selections are, particularly for low speed, low height, low power display at various air densities. Even if you select the optimal blade, a used blade has often been randomly shaped by a tobaccy- chewin shaper with headphones on, so for true entertainment, a 3D scan of actual blades and simulated wind tunnel will show what is truly happening. Probably there are a lot of high power engines making pavlova from air today with inefficient blades, but as long as the thing flies, nobody is wiser. Unless you are going for a speed record, no one is really driven to look for something better and the topic of blade design is obtuse for most. The thing that will change is the lack of parts, a race between Rotol hubs and HS blades with meat on them. Then somebody has to invest in large forgings. I vote Beermat to run this operation!
powerandpassionGB, thank you for confirming PR Blue undersides and the interesting Avenger story! For the sake of a future searcher I might load a few PR Blue component images to provide a definitive record. Also there are fabric remains in aluminium finish, so I believe the Pacific scheme in 1945 was silver up top, PR Blue underwear. Currawong, very interesting story, particularly about the revetments lasting into the 60’s, will PM to try and get more details.
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