Ernie Lazenby wrote: ↑Thu Feb 28, 2019 6:45 pm
Joerg, best you and I keep away from mentioning how to alter Octura surface drive props to get the best from them we will send folks to sleep. ! Some of mine are so thin its a wonder they work at all. That's not to mention 'tipping' and 'cuping'. Its all a black art!
I'm a bit beyond reworking Octuras. I have my own geometry 3D printed and then casted in aerospace steel (17-4PH). Many consider props as black art or voodoo. I wanted to understand how props work and what I need to modify to change certain behavours. Thus I searched the web and all kinds of publications. No single document described it all, but inbetween the lines, analysing a full size race prop (Rolla) and a Russian tether boat prop, plus adding my own experience I came up with a pretty decent understanding. I'm still far from understanding it all - but wouldn't want to say its black art or voodoo. In the end its physics and the basic behavour is predictable.
I'd still like to see how such K3 or K4 props looked like.
f1steveuk wrote: ↑Fri Mar 01, 2019 9:36 am
I'm in two minds about Du Cane's books.
...
As an aside, would those with those books (I cannot find mine, house move) give me a list of Du Cane's qualifications, I fear I may have sold him short !!
I think I know what you are saying. But considering the time when the book was published (1st in 1951 I believe) and thinking he wanted to publish his knowledge as best as possible, then I think its still a remarkable book worth owning. There are books around, like THE Propeller Handbook, which helped me less.
Anyway, looking forward to your new book. I own a copy of your DC book (besides most others about K7 and DC).
Ernie Lazenby wrote: ↑Thu Feb 28, 2019 6:45 pm
Joerg, best you and I keep away from mentioning how to alter Octura surface drive props to get the best from them we will send folks to sleep. ! Some of mine are so thin its a wonder they work at all. That's not to mention 'tipping' and 'cuping'. Its all a black art!
I'm a bit beyond reworking Octuras. I have my own geometry 3D printed and then casted in aerospace steel (17-4PH). Many consider props as black art or voodoo. I wanted to understand how props work and what I need to modify to change certain behavours. Thus I searched the web and all kinds of publications. No single document described it all, but inbetween the lines, analysing a full size race prop (Rolla) and a Russian tether boat prop, plus adding my own experience I came up with a pretty decent understanding. I'm still far from understanding it all - but wouldn't want to say its black art or voodoo. In the end its physics and the basic behavour is predictable.
I'd still like to see how such K3 or K4 props looked like.
I now understand why no one in the UK has got any where near the speeds you achieve with fast electrics. Respect.
f1steveuk wrote: ↑Fri Mar 01, 2019 9:36 am
I'm in two minds about Du Cane's books.
...
As an aside, would those with those books (I cannot find mine, house move) give me a list of Du Cane's qualifications, I fear I may have sold him short !!
I think I know what you are saying. But considering the time when the book was published (1st in 1951 I believe) and thinking he wanted to publish his knowledge as best as possible, then I think its still a remarkable book worth owning. There are books around, like THE Propeller Handbook, which helped me less.
Anyway, looking forward to your new book. I own a copy of your DC book (besides most others about K7 and DC).
Du Canes book was re issued several times, finally in 1974. The final issue was much more informative than the first, as good as that was, containing information about hydrofoils amongst other new material not included in the original print.
Steve asked 'As an aside, would those with those books (I cannot find mine, house move) give me a list of Du Cane's qualifications, I fear I may have sold him short' !!
Mines somewhere in the loft I will try and find it however; re qualifications; one of my chess playing friends used to be a research scientist for British Steel then went on to lecture in physics at the local university. He mentioned to me something that has always resonated with me. One of the foremost authorities on fluid flow dynamics in the world, and whom well qualified scientists used to consult when stuck with a practical problem to solve, left school aged 15 with no qualifications but had 50 years of empirical knowledge! A Romanian.
What puzzles me about Du Cane is WHEN did he get time to study boat design? Joined the navy as a boy seaman at 14, then went on to the RAF as a pilot, then taken on by Vospers in the commercial department, and then as a director, his main job being go ensure a full order book.
From what I have read ME III was indeed destroyed with ME II, Wakefield had them in the same storage facility, and as that was completely destroyed by fire, one has to assume they both went the same way.
I hope you enjoyed the Campbell book?
Steve Holter, UK and France, and sometimes reality....................
! Some of mine are so thin its a wonder they work at all. That's not to mention 'tipping' and 'cuping'. Its all a black art!