Now, this surprised me!! by neiwil
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Description
This is HMS Pembroke, a Sandown Class Minehunter. Launched on 12 December 1997,Commissioned on 6 October 1998. State of the art, all singing, all dancing.....but fundamentally doing what all minehunters have done since they first appeared. HMS Pembroke gets interesting when you 'look under the hood' so to speak. She does not have propellers in the usual sense, she has 2 Voith Schneider cycloidal drives. This is highly maneuverable, being able to change the direction of its thrust almost instantaneously. From a circular plate, rotating around a vertical axis, a circular array of vertical blades (in the shape of hydrofoils) protrude out of the bottom of the ship. Each blade can rotate itself around a vertical axis. The internal gear changes the angle of attack of the blades in sync with the rotation of the plate, so that each blade can provide thrust in any direction, very similar to the collective and cyclic of helicopter flight controls.A low acoustic signature favours the device's use in minesweepers by minimising cavitation (usually produced at the tips of axial propellers) as the rotor does not need to rotate as fast for a given thrust. Now, this all sounded very 'Star Wars' to me, but.....The first Voith Schneider Cycloid Drive was installed on a 60-hp motor launch named Torqueo and trials were carried out on Lake Constance.....in 1928! The real surprise for me was that 2 Voith Schneider Cycloid Drives were installed on the, never completed, German Aircraft Carrier 'Graf Zeppelin' in 1938. It seems advanced thinking wasn't limited to the German aircraft industry......
Comments (15)
blinkings
Very interesting stuff my friend.
ronmolina
Nice pic and interesting information.
steelrazer
Whew. That's some heavy info,Neil.
UVDan
That is so cool. I wonder why we do not see this on regular civilian boats? Of course Alexander Graham Bell invented hydrofoils waaaaaay back when and we never see them on civilian boats so who knows. Thanks for the picture and taking the time to do some proper research. It is very appreciated. The Graf Zeppelin.....wow! I wonder what else we don't know about German WW2 technology? Hannebrau anyone? Iron Sky?
GrandmaT
Wonderful photo!
flavia49
fabulous image and info
dbrv6
Very cool and interesting.
bmac62
Oooooooo...a Voith Schneider Cycloid Drive...does it have a warp core? Now I am half way through the wiki on Hitler's aircraft carrier...somehow that story eluded me until now...good stuff. Got to go back and read what the Soviets did with the hull after they moved all their plunder back from Germany and Poland on it. Like your photo of the minesweeper slipping through the fog/mist...atta boy Neil.
kjer_99
Surprises me as well. By the way, thanks for your latest aircraft model freebie. Those are always appreciated.
fly028
Superb photo and gret text! thank you!
whaleman
The Voith Schneider Cycloidal drives are fascinating and they are extremely common now but most people have no idea what is under them. Whenever you see cruise liners docking with only one tug on standby in case of major engine failure, you can be sure they are driven by the cycloidal drives. Almost all new tug designs now use them as well.
Briney
That's just amazing... I'm still trying to work out how it works... Scratches head????
Osper
Neat one! I wonder though about such a drive on an aircraft carrier. I can think of such a use though. "on glide path slightly left of course...........now on glide path"
T.Rex
Beautiful photo of "on the way out", with waves, fog and all. Thanks for the description of the propulsion system. I've heard about it but didn't know it was on the unfinished Graf Zeppelin. The description is good, but I'd love to see an image of it (the "picture is worth a thousand words" thingy). Looking foreward to your next posts! :-)
debbielove
I'm guessing (more than likely correctly), that those drives were NOT built in this Country? Impressive though it has to be said.. But very interesting, that the Germans thought of them so long ago! Good one! Rob