Turn RH tractor prop blade to LH tractor

If it’s really 20 cm wide it’s too small 🙁 If we were looking at a commercial blade-bashing operation we’d need to be able to accommodate up to 16 inches / 40 cm

We can’t get Coopers Stout this end of the planet.. I’ll try to import some, as I expect it helps one come up with ideas like blade-twist-reversal.

The thing about the DH graph is it’s been re-interpreted by the RAE authors who were only interested in blade shape, not absolute dimensions – so they need to be added. The trick to testing whether its the same blade profile is to make an assumption of commonality and then work backwards to test it.

We know that the Spit blade is 64.5 inches hub centre to tip, so that helps – that’s your horizontal axis mark-upable right there. Take the chord at a station from the HS tabularlar figures (I used 42 inches as it’s the traditional ‘reference station’) then assume that the chord at that station on the DH blade graph has the same value. That gives you a vertical scale.. Mark up this scale of assumed absolute values on the vertical axis (I didn’t show that on the one I sent you), and then plot the rest. If it’s a different blade profile it will very quickly show up!

Re Typhoon hubs, these threads are useful: http://forum.keypublishing.com/showthread.php?133906-What-Does-This-Prop-Spider-Fit (Merlin Pete’s list) and http://forum.keypublishing.com/showthread.php?137760-Propellor-hub (The all-knowing Anneorac).

So what you really need, in a perfect world, is a DH 55/ (or 5500) hub – which is presumably equivalent to a HS 33E60.

There are crash relics out there, but airworthy might be another matter!

Mate, thank you for posting the charts a few posts up, particularly the green dot, red line station thing.

I have to admit, without the assistance of wine or beer, the topic is hard for me to wrap my head around.
Basically dH represented a design graphically and HS tabular-larily…
I probably need to put both systems side by side, crack the top off a frosty longneck of Coopers Stout, and study.

At the end of this we need to hire a supermodel to do a basic youtube explaining prop design for dummies.

There is an auction here tomorrow of an old industrial concern with a roller forging mill that looks like the same size as the dH roller mill in the 1940’s, that could probably turn a billet into the basic aerofoil, prior to final forging. Or slowly manipulate a RH tractor blade to flat as per Mad Max option. It probably weighs 50 tons. I really don’t want to bid on it because it will cost a lot of time and money to remove and transport it.

Lot 1370
https://www.mgs.net.au/auction/catalogueitem.html?a=7854&ps=255140

When I said about initially having to use an existing 6,000 series DH bracket prop (because the Hamilton 33E and the blades developed for it didn’t exist yet) I honestly had not seen this pic of the first prototype! Compare with the Spit/DC2 – the same, just longer 🙂

[ATTACH=CONFIG]246251[/ATTACH]

The waters here are quite murky.

A lot of the problem comes from the fact that even if shaft diameters were compatible (and here I bow to Anon’s practical experience), the scale of horsepower applications were different. The US were happy with SAE50 up to 2,000 horsepower. The UK went from SBAC5 to SBAC6 at – what – the 1,400 horsepower of early Hercules?

It looks like the Typhoon hub would have, initially, been neither a 33E or a 43E. The 33E was introduced in late 1941 (the type certificate was issued in March 42), to cope with horsepower above 2,000 so it looks like, at first, Typhoons would have flown with a copy of a blade designed for the 23EX, and some other kind of hub (on the assumption a 23EX machined out wouldn’t cut it, as per Anon). The other thing to bear in mind is that blades were interchangeable between hubs of the same shank size, and some are still certified as such, like the 15 ft blades on the C-46, which are certified on both the 33E60 and 23E50 hubs, at different power ratings.

De Havilland, in their brief potted history in a 1956 ‘Flight’ , say they redesigned the Hamilton bracket hub around 1939 to fit size 6 splines, as there were no US ones . These of course needed blades, and https://www.flightglobal.com/pdfarchive/view/1938/1938%20-%200090.html shows a potentially 14′ 6″ prop. As far as I can tell these were first used on the Hercules powering the Shorts G class (not the ‘1939 generation of bombers’ mentioned in the flight article).

DH weren’t designing blades in 1938, so the blades pictured would definitely have been based on a Hamilton blade design. (Interestingly, re the design numbers, the 14′ 6″ pictured would be 14′ 7″ on a Hydro hub).

I can only presume that, in the absence of what would be the 33E60 at the time of the Typhoon’s design and first flights Hawker – if specifying a Hydromatic – would have needed de Havilland to design their own Hydromatic SBAC6 hub – or fly the early aircraft with an SBAC6 bracket prop (more likely?), complete with existing big blade design minus 6.

Perhaps later, with the availability of 33E60′ and more importantly 33EX’s, this changed. – and I think I do detect a variation between prototype and in-service prop blade designs as well. I would be keen to measure a Typhoon blade against those 15 foot blades listed against the 33E60 in HS130.

Looking at the dates on the Type Certificate, the 43E60’s were post-war (DC-6 etc)? I stand to be corrected on this.

Looking at a few images, the standard ‘in service’ dp4551157 Typhoon prop is definitely, in my opinion from years spent staring at such things, not a full ‘basic diameter’ blade. From the ‘blunted’ tip it looks like something between -6 and -12

Just some observations really, I am sure it doesn’t help!

Rats. Is it worth looking at those 15ft blades , eg 6491, “minus 12”? Might even have been what was done.. more blades were in fact used ‘cropped’ than ‘-0’

The 6159 is type certified on the 23E hub and has a LHT equivalent (also type certified) of 6160.
The 6359 is also type certified on the 23E hub and has a LHT equivalent (also type certified) of 6360.

I’m hoping the other two (6173 and 6223) show up on the hub for the Typhoon, once I figure out what exactly that hub is, if it is a 33E or a 43E equivalent.

Edit. They don’t show up on the 33E or 43E series of prop hubs. Not on the Type cert for them anyway.

******.

I don’t have a better version, normally the NASA search engine gives near-perfect copies but this time it points to this blobby one that’s also on AERADE.

I see those numbers too. As well as 6159, HS130 also gives 6359 (as 6159, but with chafing ring (sounds painful)), and 6895, 6899, 6921, 6969, 7019.

I expect those last five were later than the July 1943 document.

Worth measuring the blade the project has, see whether it’s a HS 6160A-0 as well as a DH – on the face of the figures, it looks similar. One thing I am sure of, my DH numbering system worked for bracket blades, but not Hydromatics.

So trying to read the NACA3G26 diagram, the blade designs for the 14ft prop were:

6159, 6173
6223, 6559
6283 – NACA Tip

Just trying to read the numbers – you may have a better resolution file to work from.

Regards

Graeme

..and in case of doubt, the FAA Type Cert for the DC-2 has the original propeller fit as 6111A-6:

[ATTACH=CONFIG]246216[/ATTACH]

Yes please, those sound interesting..

After I’d been skipping around the room for a bit, Mrs Beermat said ‘Yes, but does anyone really care’? I kind of saw her point, but then I read her your comments and said ‘See! Told you!. What’s more, you do realise this will make me irresistible to women, don’t you’?. To which she replied ‘Well, I can bloody resist you’ and walked out of the room. Anyway..

Here’s the chart from an RAE research paper, as annotated by me – ‘Propeller V’ is the DH 55409 of the Spit Mk I.

I converted the ratio r/R into absolute dimensions, and plotted on the stations as laid out in HS130 (Red Lines). I shifted by half an inch to account for the differing hubs.

Taking the reference station at 42″ as my datum, I then plotted the chord figures for the 6339A at those stations (little green dots – they are there if you squint) – and VOILA!! Right on the line.

[ATTACH=CONFIG]246200[/ATTACH]

HOWEVER I cannot make sense of the thickness/chord figures produced from the Hamilton Standard tables (as thick as a Spit 2-blade wooden prop??? Am I reading this wrong? Probably), and the ‘twist’ figures don’t match either.

So what we have here is a legacy plan-form, not the blade that the Spitfire’s was copied from but a ‘ghost’ of that blade, with a different twist. It does demonstrate one thing that we already knew, really, and that that these early DH blades were copies.

I do have an ace up my sleeve though – A 1943 NACA report shows the 6339 to share both basic diameter and ‘Activity Factor’ variation with length – and therefore exact planform, with two bracket/counterweight blade designs. These were 6103 AND 6111

[ATTACH=CONFIG]246201[/ATTACH]

One of these two, I’ll bet my missus, is the Spitfire blade. 130B table 3 says the 6103 is thinner than the 6111, but that’s all it says. No numbers.

Sir Beermat (knighted for services to correlating DH blade data with HS blade data),
Well Done. Tho your head be so full of data that this achievement seems fuzzy and inconsequential to you, so was Edmund Hillary’s head on that first summit of Mt Everest. Never before in the history of blade manuals has such a match been made, and shared.

I think today you climbed Mt Kilamanjaro, but it’s got to be Everest or bust.

After you have finished your reward pint, can you post the graphical 55400 DH info with the tabular 6339A data so I can grow in knowledge about interpreting this kind of information.

The 130A manual blade data from the 1930’s -40’s will be found, never fear.
AP970 Design Requirements for Aeroplanes for the RAF 1935 has a chapter on blades which no doubt relate to fixed pitch blades, but this will start to blend in with bracket types in 1935. I would assume that all that happened in 1935 was that fixed pitch blades were allowed to rotate once as per the Ratiers on the dH racing Comet, so the aerofoils might translate straight across to early bracket types to create the base camp for an Everest expedition.

Aerofoil charts covered in AP970 1935 are R&M 322, R&M 362, R&M 152, R&M 829, implying that these were the only ones used or acceptable for the RAF in 1935. Do you want a copy of these ?

OK, so, the Basic 6339A looks like a Spitfire 55400 – or rather, a 6339A-9 would look very like a 55409. This is a Hydromatic blade, but tomorrow I will cross reference with Bracket types.

Unfortunately, most of the early needle blades, the ones DH would have copied, are name-checked in the document but not given tables – for example the 6127 I am looking for for the WW.

Thank you Graham – all received – it went to my ‘junk’ – some email software just doesn’t recognise gold when it sees it..

I am just doing some beer mat maths, in between pretending to do my day job, and will get back to y’all..

If this doesn’t get the ladies attention then I don’t know what will.

130B has the HS blade station data which ol’ Duke with his shotgun let me have a little look at, but it’s all there now for you Beermat.
Hopefully Beermat can compare the graphs of DH blade profiles with the tabulated HS data to create some fist pumping moments where a DH apple equals a HS orange.
This information can then be used on date nights with wenches when conversation wanders off.

I did Beermat, you should have it and HS130B already. Let me know if you don’t.

Hi Graham – did you get my pm with an email?

Ed, that really is mad. It just might work.

It is on the way to you Ed. You’ll find it full of great info, but I’m also disappointed as I thought (hoped) it would have some DH numbers in it.

So Ed, are you saying that us Typhoon/Beau people are basically hooped?

Every once in a while I get out an old Winston Churchill speech collection on cassette, blow the dust off the last functioning cassette player in the southern hemisphere, and get my spine straightened by good ol’ fightin’ talk. So, “we shall fight them on the beaches…”

Sometimes the simple ideas work the best.
So, if you got the fattest, widest, longest F shank RH tractor blade from a postwar US radial and you heated it up and progressively forged the blade to bite the other way you would end up with a LH tractor “blank” with the aerofoil the wrong way around. You would need a skilled, patient forge. There are blokes floating around who straighten artillery barrels. You might need to find a temperature balance between manipulating the blade and not changing the hardness of the thrust washer, or a system of insulating and cooling the thrust washer. So hopefully at the end there would be enough meat on the fat blade to mill and grind a new aerofoil facing the right way.

So then you have a F shank LH tractor blade that would need an F shank barrel taking an E60 spider. You might need a good hub shop to work that out and a certifying engineer for an F shank barrel where there used to be an E shank barrel but you are actually going stronger with the whole setup.

There is a reason Mad Max was created in Australia….

Would love a geez at the T.O 03-20CC-4, otherwise known as AP2121A&B…

I was joking before, but it honestly might be easier to reverse the Sabre! http://www.epi-eng.com/piston_engine_technology/reversing_engine_rotation.htm

..or build a new reduction gear?

So Ed, are you saying that us Typhoon/Beau people are basically hooped? We now need to source the roll forging forms and the hammer forging forms before we can progress far with getting Alloy blades?

Might be back to thinking about composite blades then, although I have reservations about harmonics.

On the plus side, I just scored (purchased) T.O 03-20CC-4, otherwise known as AP2121A&B, which is the Hamilton Standard interchangeability manual. I’ll post in the props thread. Nothing about blades in it and nothing about DH part numbers, but the 23EX is in there for you so it might be helpful for you Mossie/Lanc people, but maybe not so much help for us Typhoon/Halifax/Beaufighter people with the No 6 Hub Spline.

Cheers
Graham