Commonality Between Hydromatic Propellor Models

Although I spent some time overhauling 23E50 and 4HF props back in the sixties, and maintaining 23E50 props since, I have learnt more on many aspects of those props on this thread than I did in all that time.

I have a couple of questions for the multiple experts in the thread. 

Does anyone know what aircraft type(s) dH prop blade D40550A was fitted to?

The blade, less turning gear, is 76 inches long so adding the 2.8 inches distance from the centreline of the prop we end up with a prop 13’2″ diameter (+/- and inch as diameters are measured to the next full inch).

Secondly am I correct in assuming that the serial number of APR1941nnn indicates the nnnth dH blade manufactured in April of 1941?

Thank you

Hi Oracal,

                      Thanks for the lead – I’ll have a mooch around and see what can be found.

Thanks Again.

Hi Tank. 
 

The details for ‘Air Diagrams’ such as the one you a seeking can normally be found in AP 113. A good point to start from would be if you can find a wartime edition of AP113 and so find its official number and title. 

There is a similar issue with DH engines. DH engine parts obviously have DH part numbers. However, many parts made for the MOD have totally different suppliers Part Numbers – and different batches – for the same part – can have differnt Part Numbers. Thus – for an identical part – you could have one with a DH PN, then several – all with different PN’s from suppliers. For this reason – a book, let’s just call it a Parts Number Translator was produced. I’ve met several people who have seen these in the past – but have yet to find a copy….! If anyone know the whereabouts of a copy – please let me know…!

It would be a great chart to find and share, indeed. DH was licence built Hamilton Standard. There are some ‘thin’ interchangeablability columns in HS literature, from memory. 

Hi folks – I’m after a legible copy of the De Havilland Propeller Component interchangeability Chart – as shown in the accompany advert below. Does anyone have an info’ on this by any chance….?

It’s the upper section on the HS-pattern DH Bracket-Type airscrews that I’m specifically interested in – the 1000-Series to be more specific.

If anyone is remotely interested in this topic I am scraping it off the bottom of the vegetable storage compartment in a sharehouse fridge, so the search function on Key brings it up. Postwar it seems there was some consternation between UK airscrew concerns – Rotol, Fairey and dH- in respect of design calculation for the purpose of competing for Air Ministry tenders. So the SBAC came up with a design guide to unify propellor theory in the immediate postwar. Surprisingly a copy was recently found in Israel and has been delivered by camel to my desk. It seems even the original designers had an incomplete grasp of the dark art of propellor design and much was learned in continuing wind tunnel work. I am starting to grow away from aluminium props from the simple realization of how difficult it is to contemplate forging blanks, and how limited the demand for obscure LH and RH tractor types will ever be. With some understanding of blade design it is still possible to plunge into the remains of the great US commercial airline legacy, and make remaining blades work at a fraction of their original efficiency for display aircraft operated within a small fraction of their original design capacity. No one will really notice. A point  of wisdom raised by a certain Canadian restorer is that a timber blade, in a nose over, will sacrifice in preference to an unobtanium engine crankshaft, and this seems very sensible indeed. So its almost like designing a rotol -Jablo type ‘socket’ to fit into a HS hub arrangement is one pathway to provide a solution for unique profiles and tractor arrangements for the next 50 years, if original blades finally run out. Apparently the HS profiles made in the Czech Republic are machined from billet, and modern vacuum smelted alloys can seemingly allow this. You still need upset forging at the base of the blade, but this is a common step to any profile. A funny thought is that with electric propulsion, everything old is new again, as blades are the only way to convert electric torque into getting to a destination. Perhaps, with infinitely variable RPM, modern sensing technology and computing power, old blades that constantly, individually, and as a team, adjust their pitch and RPM offer a whole new field of development in the dark art. 

Beermat, 6105 factoid is from R83.
R83, rudely, does not deal with 6103, it is a dH document which would not concern itself with mere Spitfires…
I have no take on odd numbering, or the numbering system in general. A rational explanation is that the system was designed to baffle the enemy. A more plausible explanation is that it was related to a dartboard in a pub.
In relation to the drawing, I have been waiting for Brexit to resolve, in case the British postal system collapses, and the drawing is sent to some infernal Brussels based limbo. So it should arrive after the 31st October, if the United Kingdom still exists. Another explanation is that I haven’t been able to find which dust encrusted hard drive I left it on yet… I know its there…there are a few more that have come in also, on a purple memory stick next to the pot plant next to the book case, as long as nobody does something stupid like clean up the clutter…now..where did I leave my coffee?

Hey Ed, is that 6105 factoid from R83, or is it from my Rainman approach to blade numbers and the spreadsheet I was circulating back in April? If it’s the former, I am dead chuffed to have my inklings confirmed by the horse’s mouth! – (as also are my workings out about the 6501).

Does R83 (sorry, I only scribbled down bits of the one I saw in Farnborough) confirm Hamilton Standard 6103 for the ‘other’ 5,000 blades, the 11’6″ basic diameter type, as per Spitfire?

What’s your take on the odd numbering of the Hurricane’s DH prop, an 11-foot 55600, as per another thread (the one about Hurricane nose cowls, somewhat drifted).

Finally, do you have that drawing you were going to send?

Cheers,

Matt

Like Walt Disney kept in cryogenic storage this topic is worth defrosting from time to time. A most interesting read is dH Report R83 which deals with the setup and evolution of propeller types for the Mosquito design. Starting from conceptual in 1941 to the evolution of paddle blades in 1943 it confirms the following :

Most US and British types using bracket props with E shank/ SBAC 5000 shafts used 6105 master blades, licence built by dH UK as P55(200) – Fairey Battle etc
The hydromatic equivalent blade was 6153 ( no numbering logic, shifting from 6105 to 6153) in the UK P455(200).

At this point dH UK starts to evolve its own designs, eg new pitch changes being P455(800), introduction of flared roots P455(1200) through 1942. As engines got more powerful, dH starting looking at 4 blade setups. So this confirms that dH, separate to US Hamilton Standard, was evolving its own blade designs. There was a healthy rivalry between dH and HS around ‘who’s blade is better’, in that the report shows blade studies conducted by dH being compared by HS. Improvements are not huge – an improved blade design might only result a 5 mph speed increase. In wartime, this might be a matter of life and death.

I hypothesise that German Jablo props and timber Rotol propos were easier to tweak, in that the manufacturing method, basically whittling away wood, allowed the rapid evolution of blade refinements. So dH was in an urgent, dynamic design environment were it sought constant, minor improvements, and was willing to change forging dies for short runs of aluminium blades. At this time, the US was on a different journey, trying to mass produce standard props.

Independently, HS evolved the paddle design, based on the 6501- 6507 master blade design, incorporating new theories of laminar flow, and some of the pitch distribution gleaned from UK experience. HS was largely producing blades for US radials, so no spinners to contend with.

At this time , Mosquito production in Canada and Australia was introduced, with a preference for US blade supply. dH UK wanted the US to manufacture their ‘needle’ P455(1200) design, using a four blade setup. HS resisted, as the 6501 was in mass production for a wide range of US aircraft. A debate using calculus ensued, which showed that 4 needle P455(1200) equaled 3 ‘paddle’ 6501 at height, but paddle blades gave shorter takeoff. This, and mass production, determined that the 6501 became the norm for Canadian production, and US supply to UK.

One problem remained, the 6501, designed for radials ( eg Corsair) fouled the RR designed spinner. Either the UK had to retrofit all spinners or the US refined the 6501 to clear the spinners. This they did, producing the 6519 that fitted the spinner, (which the Australians also chose to manufacture under HS licence). So the 6519 ‘paddle’ became the norm for Mosquito and Lancaster, while the UK continued to manufacture the ‘needle’ P455(1200) as a three blade setup, good for ‘most purposes’. So you can see aircraft in the same Squadron with both setups.

One problem with paddles was the governors for needle blades not having enough flow or pressure to regovern the blades in a dive. The blades would overspin, sometimes breaking the engine. So higher spec or US governors had to be fitted to resolve this issue.

Perhaps the only evolution of the 4 blade needle setup was the Highball Mosquito and following Sea Mosquito, where short takeoff from carrier deck under load, using a single stage Merlin for performance at sea level, was the main requirement.

The report confirms that dH UK evolved its own designs, and in a three blade setup, these were better than equivalent US HS needles, eg 6353.
The evolution of the 6501 master ‘paddle blade’ and US mass production introduced the ‘paddle’.
The process was dynamic, and small increments in speed, reductions in takeoff were the desiderata.

Today, most display aircraft are operated in an envelope which would allow the fitment of what a 1945 designer would call ‘unacceptable blades’ in that potential speed is reduced or take of distance increased. Understanding these factors, and the masterblades from which many applications were determined, can allow the safe operation of historic aircraft with different blade setups, where the factors are clearly understood.

A little late, but running down Spitfire propellers.
The first production batches were fitted with a two-blade wooden prop (sorry I can’t find the name, but it was not the Watts type fitted to the Hurricane)
This was replaced by the three blade metal DH variable pitch (2 position) De Havilland. De Havilland were asked to convert these to constant speed but dragged their heels arguing for the Hydromatic instead, or could not agree a price. Surprisingly, after the Battle of France there was a scramble to get all the DH bracket props converted to constant speed, and all the necessary parts appeared in an astonishing short time.
Rotol had been formed to get a source of constant speed propellers, but initially the Hurricane was given priority as being seen as more in need, and appeared in the BoB (some in the BoF) with the Spitfire spinner, which was too wide for the nose of the Hurricane.
A Rotol three blade metal (magnesium alloy) prop was fitted to one squadron of Spitfires in time for Dunkirk – there is a picture of one shot down on Dunkirk beach.
The production Rotol three blade prop was intended for the Mk.II Spitfire built at Castle Bromwich with Mk.Is from Supermarine retaining the DH – this was generally true but apparently there were exceptions.
Spitfire Mk.Vs can be seen with either the metal DH or the wooden Rotol – though this is a later less rotund spinner. Presumably whether they came from Supermarine or Castle Bromwich, but that’s a guess.
The Hydrodynamic DH prop was introduced partway through Mk.V production. Whilst the problems seen at Darwin were indeed linked to the use of the DH Hydromatic prop, similar problems of cold soak had been seen on PR Spitfires with DH props, and from the dates these would have been the bracket version.
The Spitfires with the 2-stage Merlins had four blade Rotol wooden props.
Then you go to at least two different sizes of five blade (the Mk.22 and 24 had bigger props than the Mk.14 and 21) and the contra-rotating ones. I pass on identifying them.

Can anybody help with information on blade design 5101, what aircraft were they fitted to?

Thanks! Nice and pragmatic that. ‘These are the tolerances.. unless you go beyond them, in which case THESE are the tolerances’. But I see the point too, you have to fair to one set or t’other.

B side

Easier than transcribing !

Yep, summed it up nicely. What we end up with is lost knowledge – those making the rules about who gets to know what and what archives get thrown away have no concept of what makes a blade right or wrong, or what is commercially sensitive to their operation and what is only used on one currently half-built eighty year old aeroplane. All they know is a) if people occasionally ask for it it must have value so they can’t have it or b) if no-one asks for it it gets burned.

The irony is that outside of modern military or commercial applications both performance and efficiency are becoming increasingly terrible, as no-one asks for the information any more and the ‘all props are the same, innit’ thing takes root*. When an organisation like Hercules props come along and apply the lost knowledge they sell shedloads as word gets around that ‘Jeff’s kit-built whizbang is faster and flies higher than mine, on less fuel, since he bought that prop.. who are those guys again’?… but this only applies to wooden props, at the moment.

In the modern spirit of openness, here’s the summary of what I have gleaned so far:

[ATTACH=CONFIG]257302[/ATTACH]

Does your 130 explain what the “B” column refers to in the 6127 figures?

*I’d be interested to know what the performance comparison between the Mark 1 Spitfire with re-worked but still wrong T-28 prop blades and the other two with reverse-engineered 55409’s works out like.

I do know for a fact 6AD Oakey had a prop shop at the base during WW2..Most likely had one at Amberly as well.

Beermat, for the sake of your legacy, and for some thumb sarking infant that will be searching this thread in 25 years time, you should repeat the table here, in respect of hydromatics. The scintillating conclusions may be lost on the other thread.

This field is filled with vendor driven confusion and unhelpfulness, driven by an archaic, low cost IP protection strategy, which is to keep information out of the public domain. It goes against the spirit of the times, where youngsters today are growing up with ‘open source’ software, and cracking open closed information systems. The commerciality of aluminium props for historic piston aircraft is so marginal, you wish that someone would just open the door and let it go, but I suspect that the folks in charge now don’t really have the understanding of the topic that the 1960’s engineer did, so can’t find an informed basis to make a decision about this material. It sits in the too hard, too marginal basket. It looks like the US palmed it off to the Czechs, and USD sales to Texan oilmen with Mustangs still makes some Pilsner drinking accountant see big windfalls, so prices stay up. A few sales a year of custom jobs averages out OK. It’s a formula that suppresses the growth of the historic scene.

The lack of commerciality is driven by the tightness of 95% of wallets in historic work – the obvious preference is to adapt second hand goods rather than invest in the eye watering cost of new forgings, or even a finished product from a suitable vendor. Somewhere in here the requirement for new, sound blades, obscure LH tractor blades and ‘once offs’ needs a solution, but it will never make you a millionaire. It really is a labour of love. If you want to see more stuff in the air, some other commercial formula has to evolve.

The only weird idea that might work is to rent blades, ie use your knowledge to find/adapt suitable blades then rent them out. It’s buy cheap (your money), sell dear (over time), basically vendor finance the end user, break down the cashflow so more things can fly safely and affordably. Somebody has to stump up the risk capital and face the pressure of trying to make that capital work. It’s really a labour of love, trying to at least preserve capital, making judgement calls on what to stock, to preserve the capacity. Historic prop making is a fabulous way not to make money.

I sense this is a temporary opportunity, adapting still plentiful HS material washing around the world into custom applications. In the fullness of time Jablo type blades fitted into a universal ‘historic’ hub/prop shaft combo can keep things going for 100 years.

What I notice is a diminishing pool of aluminium blade shops with a diminishing pool of grey heads which doesn’t bode well for the next 25 years. Also some crazy, mystery grinding creating mystery profiles, albeit with the right numbers. Grinding is a thankless task and you won’t find too many aerodynamicists with a grinder in hand. The pool of experience from the 1940’s to 60’s, that you could expect an informed result from a supervised labourer, might not be there anymore. Who cares, as long as the thing is balanced. Performance doesn’t matter any more. Folks are maybe doing interesting, secret things matching Tracker and Trojan blades to WW2 types and there will be more and more of this, without any regulator having the experience to make a judgement call on it. It’s like radium dials, waiting for some catastrophe to spur a response….

In the meantime you can become to go to guy to resolve dilemas. Here’s the 1947 groups and 6127, enjoy !

I have 130B with the station tables (you shoulda asked!), but the 130 sounds very interesting, as it should include some earlier (and thus mostly extinct) ones. Still, the ‘families’ in 130B do indeed help a lot with making connections!

Did you spot from my spreadsheet that by doing the station shuffle (and calling in some maths, eg. realising that activity factor rate-of-change with cropping is a ‘fingerprint’ of blade shape) I have already identified the Ham Stand ‘master’ blades (6105/6353) from which almost all the DH bracket blades and many Hydromatic equivalents were derived, along with an idea of how they were tailored to applications and what the numbers mean? Also, 130B has a table for that blade – Incidentally demonstrating there was no design data implicit in HS drawing numbers.

One specific request, though.. does the 1947 vol have station data for the 6127? That’s the master for the DH 4,000 series.

You know that armed with this stuff, and knowing that twist was centred around sectional C of G, it’s possible to make accurate blades to order via CNC? I understand that Avia in CZ can make blanks sufficient to manufacture 6903’s (which are E-shank, ie 5,000 series, ie Spitfire/Hurricane/Battle/Whitley/Roc/Lysander/Lancaster/Hampden/Younameit), from their website (http://www.aviapropeller.cz/products.htm)? Nice and broad, the blanks should be sufficient to re-work to a 6105/6353, ie. lots of British props (will need checking – the main issue being the twist). They also make the 6547, a D-shank blade, which might just do for the 4,000 series as well.

However, there is the ‘handing’ question, and I am not sure about the licencing issues. We should get our heads together properly on this.

Recent finds (finally) : Hamilton Standard Catalog 130 (1947) and 130B (1958) , with blade station tables! With blade station tables!! With blade station tables!!!
1947 presents blades in similar ‘families’ or groups. The closer the group to each other, the closer they seem to be in design. With the blade station tables, you can run your finger across the data and start to see ‘what will match with what’, in terms of whittling an apple into an orange.

Now I am thinking of getting a uni student to transcribe station data into an excel, to create basic line graphs, to get a ‘shape’ of data. This shape could then be shifted up or down the stations to get a sense of which profile is being shifted up or down to develop different affects. Now I am a dumbo at maths, so I am open to other ideas on how to find commonalities across this data.

There is also Rotol File 200A : Rotol Propeller Data which lists which Rotol airscrew is used on various British types.

Not ignoring – I just don’t have the numbers to hand. I have just moved house, and everything is in boxes. I might have something buried deep somewhere.. but it may take time to unearth.