Today I visited Hendon and while looking at the “as found” Halifax display, I noticed something I hadn’t noticed in earlier visits….namely that the (shattered and splintered) props were wooden.
That surprised me for a multi-engined type, especially one as advanced as the Halifax (I would expect them on earlier, early-mid, thirties types).
We’re they fitted by design or as a material conservation effort?
Can anyone think of another four-engine heavy bomber that used wood props?
By: dogsbody - 26th April 2018 at 01:35
Info:
http://www.enginehistory.org/Propellers/Rotol/rotol.shtml
http://www.enginehistory.org/members/JabloBlades.php
Chris
By: dhfan - 20th April 2018 at 15:09
I obviously remembered – or didn’t – George Dowty’s history wrongly. Perhaps an author had worked with him previously.
I’m pretty sure I read about the constant-speed conversions in The DH Story. I’ll see what it says. It’s a thick book, I may be a while…
By: Graham Boak - 20th April 2018 at 13:36
Thanks for the correction on Rotol.
However, DH were asked to produce their conversion before the war began, but failed to agree a contract with the Ministry. I’ve seen two reasons quoted. One says there was a disagreement with the Ministry over the price, the other was that DH were holding out for the introduction of the Hydromatic system of control. I suspect that this is a conflation of two different arguments. For a long time it has seemed clear to me that actual conversion could not have been designed, prepared for production, produced and fitted within the time quoted. So in all fairness DH must have actually done much of the work in advance of an agreed contract. There is a story, usually linked to the Mosquito, where one DH employee is supposed to have asked “Will we ever get paid for this?” to which the other replied that if if didn’t get done then it wouldn’t matter anyway. I feel that this story (if not entirely apocryphal) is much more appropriate to the constant-speed propeller conversion. However, that still leaves almost a year between the initial request and the July refits. I feel that many fighters could have been so fitted earlier, so I stand by my judgement.
By: Arabella-Cox - 20th April 2018 at 08:50
George Dowty was ex-Gloster and left to establish his own company, Aircraft Components, in 1931. He may have supplied hydraulic systems to Rotol but was never employed by them.
By: dhfan - 20th April 2018 at 00:05
Not Dowty and Rolls-Royce – ROlls-Royce and BrisTOL. George Dowty was an employee of Rotol, I think ex-Bristol but would have to consult a book to confirm, before leaving to set up on his own.
Accusing DH of dragging their feet is extremely unreasonable considering all Spitfires and Hurricanes were converted from two position to constant speed at the squadrons in a matter of weeks. It was all done without contract cover too so there was no guarantee they’d ever be paid for the work.
By: Arabella-Cox - 20th April 2018 at 00:05
Lanc II had Rotols – due to having Hercules engines!
Stirling only ever used the de-H Hydromatic units. I don’t think I’ve ever seen or heard of a Stirling with anything else – though there is bound to be an exception, even if only for test purposes.
Halifax had the lot – 3-blade de-H Hydromatics and Rotol three and four bladers, often with three-blade props inboard and four-bladers outboard in an attempt to cure vibration/resonance problems.
Anon.
By: J Boyle - 19th April 2018 at 22:59
Thanks for the reply.
Of course, anyone who has read anything about UK aircraft has heard of Rotol props, however I wasn’t aware of their composition.
I guess coming from America, where virtually all large aircraft since the late 20s (such as the Ford “Tri-Motor” transports) had metal props, I was surprised by the Halifax.
By: Bob - 19th April 2018 at 14:47
Bit of a glimpse at the methods of construction can be seen in this old Air Ministry film of the squadron repairs of wooden propellor blades
By: Graham Boak - 19th April 2018 at 14:01
Rotol propellers were almost entirely wooden, apart from a few early magnesium ones. They were not carved from the solid (or laminates) but made from compressed resin-impregnated wood. They were fitted to a wide range of British WW2 aircraft. A number of German aircraft (eg Bf109, Ju88) also used wooden props. There’s no particular reason why a multi-engined type should have metal props compared to a single-engined type such as the Spitfire, whose later marks were almost entirely Rotol.
The Lancaster however used DH (Hamilton licence) metal props. I don’t know offhand about the Stirling. Rotol were originally formed (by Dowty and Rolls-Royce) to provide an alternative source of supply of constant-speed propellers, which turned out to be particularly useful given DH dragging its feet on the conversion of their existing variable pitch props to constant speed. Rotol’s choice of wooden props was, as far as I know, purely driven on performance grounds, being considerably lighter than the DH examples. On the other hand, the Sea Hurricane Mk.I had to have the heavier DH props to bring the cg forward after the installation of the arrester gear, so circumstances alter cases!
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April 18, 2018 at 11:12 pm