Focke-Achgelis Fa 330 rotor kite deployed from the deck of a German U-boat for observation purposes

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flounderflound@reddit

I was just looking at one of these at the NMUSAF a few weeks ago.

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diogenesNY@reddit

Rotor kites are really kind of wild from an engineering (and just about every other) standpoint.

I think that the pictured observer/pilot must have been a very brave guy. :)

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zorniy2@reddit

I do wonder, why not a simpler kite or towed glider?

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PkHolm@reddit

Wings are big an hard to fold. Rotor in other hand can be made very compact when folded. I bet this thing was stored inside the boat when not in use

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I think it was stored in a compacted and semi-dismantled form on the deck, but bolted down.... not 100% sure, but have a look at the physics an engineering behind gyro-kites and gyro-planes. It is amazing and completely counteractive.

What these things could do, and how they did them will tie your mind in knots even if you are pretty well versed in aeronautical physics.

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Newbosterone@reddit

Those probably require a higher speed to remain airborne.

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zipzipzazoom@reddit

Pretty windy in the North Atlantic

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KokoTheTalkingApe@reddit

Yep. You'd think the thing would have pontoons or something so it could at least float if the sub loses speed for some reason.

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schr0@reddit

En if they lost engine the autogyro could carry it pretty near to if not directly back into the deck

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KokoTheTalkingApe@reddit

It has no control surfaces. It's a literal kite.

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Ozma207@reddit

https://www.youtube.com/watch?v=6NtI-KS45xk

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127-0-0-0@reddit

r/weirdrotors

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RandomQrimQuestnoob1@reddit

Higher ground (or air) means more observations range. Not sure how they're going to radio from that height

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tothemoonandback01@reddit

It was connected to sub with an intercom wire.

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particlegun@reddit

I wonder what happens when a Coastal Command aircraft spots them and the U-boat needs to crash dive...

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klystron@reddit

I think they were intended for use in the Atlantic where there was no air cover, and they were intended for spotting convoys. In an emergency they could descend in a hurry and throw the autogiro overboard before submerging.

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HardcoreHenryLofT@reddit

I saw one of these (not the kriegsmarine version, I assume) for sale on Barnstormers a couple years back, and decided to tell my grandfather for a laugh since he likes odd machinery. He just looks at it and goes "oh yeah, the nazis used to use those." I had no idea about them and got quite the history lesson.

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Proper-Photograph-76@reddit

Bachstelze (waigtail)

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Beli_Mawrr@reddit

I'd really like to see rotor kites in use for power generation.

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KokoTheTalkingApe@reddit

People have considered it. One issue is that using the rotor to turn a generator will slow down the rotor, reducing lift. It seems like the idea is more practical underwater, where the thing is made buoyant enough to stay up in the water even if there's no water current. I've seen a few speculative designs for something like that.

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jacksmachiningreveng@reddit (OP)

Because of their low profile in the water, submarines could not see more than a few miles over the ocean. To solve this, the German admiralty considered a number of different options, including a folding seaplane (Arado Ar 231). In the end, they chose the Fa 330, a simple, single-seat autogyro kite with a three-bladed rotor.

The Fa 330 could be deployed to the deck of the submarine by two people and was tethered to the U-boat by a 150 m (490 ft) cable. The airflow on the rotors as the boat motored along on the surface would spin them up. The kite would then be deployed behind the U-boat with its observer-pilot aboard, raising him approximately 120 meters above the surface and allowing him to see much farther — about 25 nautical miles (46 kilometres), compared to the 5 nautical miles (9.3 kilometres) visible from the conning tower of the U-boat.