Flettner

[TETOYVIENDO]

hi!, one question... what will be the effect if the "tubes" have the same little hole of the golf ball???... that will increase the forward speed!?!?! or do smething bad in the performance of the machine!?!?!?!?!

[IneedTodisco]

what is this

[Teratornis]

Did you try putting horizontal disks on the rotors? They should make the rotors work better by reducing spillage from the high pressure side to the low pressure side. See the paper by Salter et al. that I added to the Rotor ship article on Wikipedia (sorry, lame YouTube doesn't let us link in comments).

[emily92japan]

hey! so i have another question to ask you. so i have started my model ship and it is going pretty well except i can't get the tubes to spin perfectly. they just end up wobbling. i was wondering how you attached the tubes to the motors so perfectly?

thanks!

[jassibo]

I had the same problem originally. To fix it, I made solid plastic columns to fit inside the pvc. If you don't have access to a lathe, you may want to try attaching a stabilizer to the top of the tubes in order to prevent the wobble. It could be as simple as a strip of light plastic with two bearings inset in either end. The bearings would then interact with each of the tubes via an axis sticking up from a small plug in the center of each tube. Good luck!

[emily92japan]

So I was thinking about making a flettner ship model for my physics class. I was wondering what kinds of materials you used and what type of electric motor.

[jassibo]

Hi. I had access to a university machine shop so even though I used simple parts, some of the proceedures were complicated. The hull was styrophoam. The masts were pvc tubing with gearing glued to the bottoms and set into cylindrical ball bearings. The motors were each 1.5 mV (from radioshack) with a small axel with gearing on the end.

[arnauchica]

Patrik, sails need a lot of ropes and well made structures to work good. Also, sails must be controlled every time.

A rotor only needs a motor to rotate, and its more efficient than a sail. And leaves more space for the cargo.

[PatrikMacGoohan]

Would you care to explain why you are getting movement of the ship? Also, what are you trying to do? Are you trying to create a sailboat with cyclindrical sails? Seems like old fashioned sails work better even if you can get a little movement with this method.

[sb6lb3]

patrik, this is a flettner kind of ship. what happens is the cylinders on the ship spin and create a boundary layer on them. they redirect the air and it creates force to push the boat. theyre was one in the 20s and it actually went across the atlantic. they rotors are said to create up to 10 time more lift than regular plane wing which according to wikipedia is "quite surprising"

[lostinseganet]

How long did it take to cross the atlantic?

[erg0456]

You may want to investigate a physics principle called the Magnus Effect. BTW; the ship Flettner built was called the Baden-Baden. There was another one called the Barbara and there are photos on the internet of both ships.

[PatrikMacGoohan]

The tubes spin on their axis. Through friction they drag along a little air that clings to their exterior. This air gets hit with the air current from the fan. On one side of the tube the fan is pushing air in the same direction that it's moving. The air on that side of the tube will generate lift (horizantal lift), but 180 degrees away the dragged air is hitting the fan air head on. The air current here is slowed. That creates drag. The ship shouldn't go anywhere but the video shows that itdoes

[jassibo]

I was trying to create a model of the Flettner Ship for my fluid mechanics class. Like an aifoil, a zone of slightly lower pressure devlops on the side of the column with the faster wind speed according to Bernoulli's principle. A zone of higher pressure is formed on the side with a lower air speed. The ship is the "sucked" forward due to the pressure difference.

[PatrikMacGoohan]

Good job!

What would happen if you put little dents all over the cylinders like the dents on a golf ball? Do you think it would drag more air along with it as it rotated and as a result move forward even faster when you put the fan on it?

Hollow out 12 golf balls. Mount them on two spinning rods and try the experiment again. Compare the speeds of the two ships and have your paper with the results on my desk by the end of the weekend.