BeermatIf there are surplus 3E50 Japanese props then that would make some people very happy indeed – except for a few people who have just spent an awful lot of money.. I do doubt it.
Mine are rusty ex-Otter Hamiltons, relatively common so not interesting (unless you’re really into propellers 😉 ) or expensive in any way.
BeermatSo not trying to teach you anything as I know you are way ahead of me on this stuff through hands-on experience. I am more explaining myself with this..
I believe that the blades without any countering force would tend towards finer-than-optimum pitch due to aerodynamic forces alone.. The countering force in a bracket prop comes from the counterweights which apply more force the faster they spin, and are linked to provide force in the coarse direction. This may be progressively over-ruled by oil pressure in the cylinder, tending the blade back to fine against the counterweights.
In a single-acting hydromatic the tendency to fine is countered by oil pressure, not counterweights. In a double acting one there is pressure on both sides of the piston. The oil provides a force in the opposite sense to that in a CW, in both cases. This is why I argue that it is a different thing and far more than a deletion of the weights.
BeermatI have been looking at this for a while. The scarcity is not of bracket props in general, there are loads of D-shank units sloshing around – I have half a dozen in my garage.
E – shank bracket prop components are hen’s teeth, and there are in fact variations of fit. Tables of interchangeability do exist in the manuals but are largely hypothetical when the parts don’t exist any more. I challenge anyone to find an SAE 50 spline E shank BRACKET application – never mind an SBAC 50 one – since the war. Hence the necessity to re-manufacture all the components at great expense – or just use a Hydromatic instead, different spinner and all.
BeermatHi
The pitch change mechanism relied on a centrifugal effect – spinning weights on brackets – to drive pitch change in the ‘coarse’ direction in a bracket prop, so operation was somewhat different. The Hydromatic was an improved means of achieving a variable pitch prop, but one would be hard pressed to call it an improved bracket prop. Mainly because it didn’t have brackets!
It would be like calling a Tesla an improved Mini. Bit pedantic of me, sorry! It’s because it niggles the nerd in me that folk call all variable-pitch metal Hamilton or DH props ‘Hydromatic’ – not you, but I am keen on the distinction!
BeermatAnon. I am of course aware of the Hamilton bracket prop!
The problem is there are no Right Hand 3 E X’s anywhere. I was keeping designations out of it.
Machining won’t help, I believe. The problem is the spline – different number and shape.
To clarify,I was thinking about blade profiles when I talked of equivalents.
The Hydromatic was more than an improved bracket hub – it was a different mechanism.
DBenz, why did you add my ‘name’ to that quote? I have never commented on the matter.
BeermatJohn, can you put that table on here, please. I cannot find it.
BeermatJohn, your oft-referred-to OECD survey does not show third world standards, it puts us about half-way up the first world.
Arguably, no undergraduate student is well prepared for university study, or has ever been. If they were, they wouldn’t need to go to university. School is not and logically should not be a training ground for the completely differently purposed institution that is university. Only the philistines who decided that everyone should go to university think so.
Further, if university staff think university is not appropriate for half the kids they admit, why on earth are they admitting them? The point is they wouldn’t have before. It’s not the kids that have changed, it’s university admissions.
BeermatMaybe the counterweights are a red herring – it was something I read about the Canadian Hurricanes. It’s to do with attachment points IIRC.
However, there are differences -the blade roots sat 3/4 inch further out in radius terms and also marginally further forward. This comes from RTFM. Furhermore the Hydromatic unit was longer. So – same base diameter, but needing a different curvature. As you say, the bracket type sat under a shorter spinner because it could. This, and differing modes of attachment meant a different profile. Put basically, to apply a ‘correct’ spinner would need a smaller hub – as Andy said, that’s why that Spitfire uniquely has the correct profile spinner – they spent silly money getting the correct prop assembly replicated and no-one else has.
There were blade equivalences with Hamilton blades (I listed them in some other obscure thread) but once dh started doing their own this broke down. Because the hubs were different sizes changing from bracket to hydro on the same aircraft actually made your prop diameter slightly larger, if you stuck to the same blade profile.
Whether there is a US Hydromatic equivalent to a Spitfire or Hurricane bracket-type blade is the 64,000 dollar question, and it depends on which side of the Atlantic the original profile came from. No-one knows.
So here’s the difference between Spit DH Bracket and Spit DH Hydro (of which there weren’t all that many) – it’s subtle but it’s there – Aussie Spit on left (Hydro), Standard DH Spit prop middle, and Rotol for comparison right.
BeermatI wish I could help – sometimes one comes up against the edge of surviving knowledge, and it gets difficult. All you have is a ‘probable’ and you are scratching around for the smoking gun document or find. I guess you’ve been there a few times with the fabulous Bluebird project.
I believe Dunlop have done special runs in the past? Worth asking.
BeermatAgreed. The problem is an absence of bracket-type DH props – apart from the extraordinary (and extraordinarily expensive) new-build one on P9374 Andy mentioned. That might be the only three-blade one flying now – Hamilton and DH simply stopped making them 75 years ago.
The blades sit differently on Hydro hubs, and the internal spinner archtecture doesn’t need to accomodate counter-weights.
BeermatPeeps
The cartoon character was called ‘Gruffie the Gremlin’ and Bob Beaumont painted it everywhere. His grandson (who occasionally frequents this forum) has a letter to his dad from Bob featuring Gruffie.
The aircraft was probably P7056. Certainly that was as close to a ‘personal aircraft’ as Bob Beaumont got – His Whirlwind ops read:
20-Jul-43 P.7056
03-Aug-43 P.7111
13-Aug-43 P.7056
15-Aug-43 P.7092
17-Aug-43 P.7056
08-Sep-43 P.7056
09-Sep-43 P.7056
18-Sep-43 P.7056
Yes, P7056 was ‘Pride of Yeovil’ when it left the factory, and there is a photo of it with the legend under the cockpit – pre-delivery and no codes. However, don’t forget that it would have been repainted from brown/green to grey/green between being new and 1943. Any inscription would have gone.
That ‘Bellows’ below the cockpit was chalked on. As it happens, 263 got itself named the ‘Bellows Squadron’ and there were a whole bunch of ex-pats in Argentina (the Fellowship of the Bellows) who thought they had funded an entire RAF Whirlwind Squadron (They hadn’t). This didn’t matter until a Gaumont News crew turned up to film something for Argentinian release – all 263 aircraft had to have ‘Bellows’ hurriedly added under the cockpit, which you can see in the footage. This probably accounts for HE-W carrying ‘Bellows’.
I do not know that it WAS P7056, but there’s nothing to indicate that it wasn’t. I have done a lot of research, too long and boring to put here. The reason for this effort being it is currently the intention to put our replica in this very scheme, in honour of Jeff’s granddad and also John McClure, a supporter of the project who flew the same aircraft when with 137.
BeermatA touch contradictory, that. Not in the way you are suggesting – what I mean is that you are claiming adopting a ‘caring’ profile in business is done cynically for cash appeal, but at the same time are arguing that the co-op has no cash-appeal because it has adopted a caring profile.
Not that the rest didn’t show an alarming clarity and rationale!
BeermatEthics and caring do not have to be paid for. I care for my daughters, and ‘Ethics’ go without saying. They are not paying me for it. Neither is my elderly mother in law, whom we spend the weekends looking after in every way. She doesn’t pay when I take her to the toilet. No one does. The guy outside the station with a Fireman Sam duvet and a dog on a string. He doesn’t pay for my ethics in helping him out. Yes, I pay, but I am not making a ‘heap of money’. In fact I break even. Does that make my help meaningless?
I am able to spare a little from what my employers can spare from making their profit. If they chose to make less profit by paying me more then as a person with ethics I could give more. Your model of the world breaks down there, as right-wing dogma always does when it encounters the inexplicable (to the dogmatists) world of real ethics.
Not that my employers will, because they are in business to make a profit. It is not to pay, or even employ me or anyone. If they could magically get what I do done without me they would. Some people are ethical, businesses rarely are. It’s how it all works. It wouldn’t otherwise.
The co-op bank did not suffer from poor service or returns for customers. Nice ‘alternative fact’ there. Some bad decisions were made, like buying Britannia.
Meanwhile, co-op high street bank customers knew what they were doing, and remained loyal. It is the apparently interdependent financial world that has deserted them. They were putting their money into a bank that drew certain ethical and moral lines in its own behaviour. As I mentioned, it may never have been a viable model in the real world of finance, to have moral scruples. But it didn’t make it wrong in the eyes of its own customers.
BeermatBy looking at the profit?
Surely the basis of Western economy is a constant effort to maximise profit in all circumstances. How is it possible to define ‘profiteering’ as something different from this?
It’s a bit like the Churchill quote – ‘We’ve established what you are, madam. Now we’re just discussing the price’.
BeermatEthical and caring might not attract the sort of people who want to own a bank. That is not the issue this liberal has, after all it is a simple fact of life.
The issue is with those that think being ethical and caring is wrong simply because you can’t sell it for cash.
Is that so bad?
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