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2-Speed Propellers - Pioneer Research

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xylstra View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xylstra Quote  Post ReplyReply Direct Link To This Post Topic: 2-Speed Propellers - Pioneer Research
    Posted: 06 Jan 2016 at 03:57
I have an intriguing topic that I hope will provoke some interesting discussion as well as yield answers to questions I have.
Experimental PROPELLOR AIRSCREWS for piston engine aircraft.
  From the early pioneering years of aviation on through to the 1940's and even a few beyond that there have been some advocates and indeed, practical experimental hardware made to investigate speed changing fixed-pitch propellers. Nearly all have been low/high 2-speed reduction gearboxes. However, I have never yet been able to locate any substantive detail (i.e. research papers, pictures, diagrams, etc, etc). I believe Armstrong-Siddeley conducted some research into this topic in the 1930's/'40's and very late, the mighty LYCOMING XR 7755 sported a high/low speed propeller gearbox this, in particular would have been of interest to learn more of its inner workings but none, so far as I've been able to find. Moreover, such little information (mostly, often just a single sentence) as I've been able to find has usually originated only from Western, English-speaking countries but nothing of, say, middle/Eastern Europe (e.g. Russia) or the the Asian far-East...
   So, is there anyone out there with their hand on the valve controlling the information-fountain - particularly the less, well-documented earlier years -  who wouldn't mind giving it a flick and putting me out of my misery!
   (NB. Just a useful hint: try taking a look at:  enginehistory.org/References/UKNA/Prop-AVIA.shtml   which contains a brilliant table of papers held at  discover.nationalarchives.gov.uk  )

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NickForder View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NickForder Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jan 2016 at 09:14
I have seen something on Farnborough research on variable pitch props during the war, perhaps on a Bristol Fighter ?
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Paul R Hare View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul R Hare Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jan 2016 at 14:12
They fitted a VP prop to an S.E.5 but its weight offset any aerodynamic advantage.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul R Hare Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2016 at 11:56
There is a picture of the S.E.5 Installation on page 127 of that well known book "MOUNT OF ACES" by who know who.

The official history of the Factory states that such an installation was also made to an R.E.8 but I have never seen a picture.
Or a test report.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xylstra Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2016 at 00:53
Hi Nick,
            thanks for your post but I fear you may have misunderstood. The V-P info is interesting but not what I'm focussed on. I do mean 2-speed propellers as in a selectable gear-ratio reduction gear-box driving a fixed-pitch propeller. Hope this clarifies.
                                      Regards.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xylstra Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2016 at 00:54
Hi Paul,
             Thanks for your post. See my reply to Nick. Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NickForder Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2016 at 09:20
Almost certainly part of the same research project though. I can't see anyone else, other than Farnborough, pursuing this sort of thing, at this time.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Paul R Hare Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan 2016 at 09:01
I have found no record of any project involving a gear box driving a fixed pitch at the Royal Aircraft Factory, or any where else, during the period up to 1919.
Maybe it was a post -war idea?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote NickForder Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan 2016 at 14:52
The Hispano in the SE was geared, and drove a fixed pitch prop, whereas the Viper was direct drive. Perhaps the notion was looked at then ? I would have thought that the weight penalty would have resulted in the same conclusion as the VP prop, though.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xylstra Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan 2016 at 01:29
Hi Paul,
             Thanks for your post. Yes, it was pursued post-war (see British Patent GB# 460149(A) and US Patent # 2,482,460A) but Farnborough need not be the only epicenter for such investigations. For a start there are privateer efforts to consider but more especially, what was happening elsewhere in the world - Russia, for instance?
   There are a lot of information 'black holes' to fill!
                                                              Cheers! 
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