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PROPELLER AIRSCREW Research......

Propellers Airscrews

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#1 xylstra

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Posted 11 November 2015 - 03:56 AM

I have a few topics that I hope will provoke some interesting discussion as well as yield answers to questions I have.
Experimental PROPELLOR AIRSCREWS for piston engine aircraft.
  Topic #1: During the 1920's 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 1920's/'30'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 or the the Asian far-East...
  which conveniently leads me into....
 Topic #2: What and how was propeller airscrew research was conducted in the axis countries for example, look at the far-reaching Japanese experimental R & D work conducted and evidenced by the 6-blader unit employed on the gorgeous Kyushu Shinden J7W1 and other late prototype aircraft. But of Japanese airscrew R & D we seem to know very little e.g. the names of the researchers and the institutions they worked for, testing facilities (wind-tunnels, etc), published technical papers, photographs, etc.
   So, is there anyone out there with their hand on the valve controlling the information-fountain 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  )

 



#2 CORSNING

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Posted 11 November 2015 - 02:43 PM

xylstra,

     Wow, that is an interesting handle. Anyway, I am sorry to say that that I can not help in your venture. But since this is the first time I have had the opportunity to converse with you; hi, how are you doing these days?

     I am afraid you have me completely bewildered. Check out your stats. How can anyone have started 3 topics and only made 2 posts?

 

Co mpletly  off gua rd, Jeff :)



#3 Heräkulman Ruhtinas

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Posted 12 November 2015 - 08:26 PM

Pretty interesting opening.

 

Cannot say much about item 1.

 

Regarding item 2. I have not much knowledge about Japanese aeronautics regarding propellers. Germans had the distinctive wide chord "paddle blade" propellers in their more powerful planes and only few 4-bladed types - as per Japanese and Allied went more to thin-chord 4+ blade designs.

 

Some say that Germans were "off" in the design but I think they were not, less blades mean less parts and hence also less mass to rotate from same swept volume.

 

Some considerations in link: http://www.secretpro...ic,13653.0.html

 

German propeller companies were VDM, Junkers and Schwarz&Heine. Lot of german research was handed over to Japan.


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Heräkulman Ruhtinas

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#4 xylstra

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Posted 09 December 2015 - 05:24 AM

Pretty interesting opening.

 

Cannot say much about item 1.

 

Regarding item 2. I have not much knowledge about Japanese aeronautics regarding propellers. Germans had the distinctive wide chord "paddle blade" propellers in their more powerful planes and only few 4-bladed types - as per Japanese and Allied went more to thin-chord 4+ blade designs.

 

Some say that Germans were "off" in the design but I think they were not, less blades mean less parts and hence also less mass to rotate from same swept volume.

 

Some considerations in link: http://www.secretpro...ic,13653.0.html

 

German propeller companies were VDM, Junkers and Schwarz&Heine. Lot of german research was handed over to Japan.

Hi Herakulman,

                        Thanks for your offering of information. Thought you might enjoy researching the following link:   http://legendsinthei...04_Ju-prop.html 

                                                                                                                                Enjoy!!  Kind Regards. 



#5 Armand

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Posted 09 December 2015 - 05:31 PM

á #1:
As the subject tend to sound like at power-up detail I wonder if the gearbox of Lycoming in the contrary might have been for reducing engine speed during cruising :-/

#6 xylstra

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Posted 15 December 2015 - 11:58 PM

á #1:
As the subject tend to sound like at power-up detail I wonder if the gearbox of Lycoming in the contrary might have been for reducing engine speed during cruising :-/

Quite probably, as it was intended to power long-range bombers/transports where range is the pre-requisite priority. Still, I am left with no comprehensive information! Frustrating, I know.

                 Cheers.



#7 xylstra

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Posted 16 December 2015 - 12:50 AM

Hi Folks,

               In the intervening month since i made my initial post I have been a little disappointed with the lack of information but for my part, I've not been idle! With much further digging I've hit pay-dirt albeit not the mother-load but still, a rich vein of glinting gold specks which I will share with you now.

   Though not confirmed, it appears the Armstrong-Siddeley research I referred to was undertaken by one Thomas Pitt (TP) de Paravicini whose technical research paper (Reference: PA1716/3/3/8, 10th March, 1941) is recorded - though frustratingly - not accessible on the discovery.nationalarchives.gov.uk database, entitled "2-speed multi-speed airscrew gears". The paper is physically held at the Coventry History Centre (U.K.). Anybody able to swing by and grab a copy?!

Also, have a look at his British Patent: GB460149(A)-1937-01-19.

   Another extremely interesting fountain of information has emerged in the form of US Patent#: 2,482,460A assigned to Wright Aeronautical Corporation. What is of additional interest is that if you scroll doen to the bottom of the patent (off-screen), additional links to other related patents appear - VERY interesting! NB You'll need to use Google's CHROME browser for the patent information to render properly (Web-Search: Google Advanced Patent Search).

    Although all of this has in some way helped to answer my own question, don't slack-off, there's still much more information out there somewhere so everyone keep on digging! 



#8 Armand

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Posted 25 December 2015 - 02:19 PM

Enjoyed a video on Youtube about dogfighting the P-47 and remembered You as the sentence: The wide 'paddleblade' prop gave the aircraft a better climb" was said!
Link:
  • CORSNING likes this

#9 Heräkulman Ruhtinas

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Posted 25 December 2015 - 04:13 PM

Enjoyed a video on Youtube about dogfighting the P-47 and remembered You as the sentence: The wide 'paddleblade' prop gave the aircraft a better climb" was said!
 

 

Paddle blades give better acceleration and climb performance, narrow chord blades give better fuel economy and higher top  and cruise speed, generically speaking.  Also in most cases you want to avoid the prop tips from reaching supersonic speeds, the exception being Tu-95. 

 


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